Chinese Journal of Radiation Oncology

中华放射肿瘤学杂志

中华放射肿瘤学杂志

Office

Journal

Archive

RSS

Download

Instruction

Template

Quick Search

Advanced Search

Chinese Journal of Radiation Oncology

	2022 Vol.31 Issue.7 Published 2022-07-15

	Abdominal Tumors Thoracic Tumors Review Articles Investigation Research Guideline Physics·Technique·Biology

Guideline

	595	Quality control guidelines for surface-guided radiation therapy
		National Cancer Center / National Cancer Quality Control Center
		Surface-guided radiation therapy (SGRT) is a zero-radiation image-guided system that uses optical tracking to capture the surface information, record and correct the setup errors between and within fractions, and improve the accuracy of radiotherapy of patients. To ensure the safety of patient treatment, necessary quality control measures must be taken for SGRT. Consequently, National Cancer Center/National Cancer Quality Control Center organized experts to formulate the guideline. The guideline covers the following topics: the definition and basic principles of SGRT; the registration algorithm of SGRT; the measurement methods and categories of SGRT; the quality control requirements of SGRT; and the radiotherapy specification of SGRT.
		2022 Vol. 31 (7): 595-598 [Abstract] ( 109 ) [HTML 1KB] [ PDF 0KB] ( 0 )

Investigation Research

	599	Survey on the status quo of human resources and scientific research level of national radiotherapists in 2020
		Li Lintao, Xu Senkui, Zhang Xiaolong, Liu Qinsong, Lin Chengguang, Li Jie, Zhang Dekang
		Objective To investigate the manpower allocation and scientific research level of radiotherapists in radiotherapy units in mainland China, aiming to provide reference for the construction of radiotherapist teams. Methods The questionnaire was designed and produced by the organizer, released in the professional committee, professional group and other channels of the radiotherapist industry, and filled out by the technical person in charge of the radiotherapy unit through the online questionnaire survey. The collection time started from mid-May 2021 to mid-June 2021. Results A total of 558 effective questionnaires filled out by radiotherapy units. The radiotherapy institutions participating in the survey had a total of 5500 radiotherapists, including 3702 males and 1798 females, 3754 with a bachelor's degree, 371 who are currently studying or have obtained a master's degree, 21 who are currently studying or have already obtained a doctoral degree, 3642 with junior or lower titles, 1580 with intermediate titles, and 278 with senior titles. In 2020, radiotherapists from 193 units published articles, those from 81 units received project funding, and those from 56 units obtained patent authorization, and those from 15 units had scientific research transformation. The participating units had a total of 1080 large-scale radiation therapy equipment. In 2020, the daily average number of radiotherapy patients was 47 900, the average daily load of accelerator patients was 44.35, and the average workload index per capita was 8.71. The average daily radiotherapy patients in county-level or below, city-level, and provincial-level institutions were 25.78, 65.68, and 173.76, respectively, and the per capita workload index was 5.22, 8.09, and 10.11. Conclusions Compared with the 2019 survey, the educational background of radiotherapists in mainland China has been improved, and the title structure has been optimized to a certain extent, and the workload of large-scale radiotherapy units is larger than that of grass-roots units.
		2022 Vol. 31 (7): 599-604 [Abstract] ( 97 ) [HTML 1KB] [ PDF 0KB] ( 0 )

Thoracic Tumors

	605	Application of prospective respiratory gating based on 4D-CT in precise radiotherapy for lung cancer
		Yin Li, Gao Han, Yuan Fangqin, Wang Qi, Liu Yatian, Zhai Zhenyu, Jiang Ming, Sun Li, Zhang Qian, Zhu Jun, He Xia
		Objective The respiratory waveform of lung cancer patients based on 4D-CT respiratory gating was analyzed to evaluate the accuracy of gating during radiotherapy, and to explore the off-target in the 4D-CT respiratory gating radiotherapy. Methods Clinical data of 18 patients with lung cancer admitted to Radiotherapy Department of Jiangsu Cancer Hospital were collected to obtain the respiratory waveform data during 4D-CT respiratory gating radiotherapy. The waveform in each treatment working cycle was compared with the waveform in 4D-CT scan to study whether there was a possibility of the off-target in the treatment of lung cancer patients. Results There were 154 treatment sessions and 20,790 treatment breathing cycles in 18 patients, among which the threshold of gated opening beam miss amplitude (Δm-en) was greater than 0 in 95 treatment breathing cycles in 7 patients, accounting for 0.46% of all breathing cycles, and the threshold of gated closing beam miss amplitude (Δm-dis) was greater than 0 in 1419 treatment breathing cycles in 13 patients, accounting for 6.83% of all cycles. Among the 13 patients withΔm-dis greater than 0, actual tumor range of motion (R_G) was greater than the sum of the value of target margin (M) and the value of plan tumor range of motion (R_T) in 7 patients, R_G was more than 1.5 times of M+R_T in 7 patients, and there were also 7 patients in the phase of rapid rise and fall of respiratory curve. The correlation efficients between R_G-M-R_T and the percentage of beam on miss phase (T_en%) and the percentage of beam closing off phase (T_dis%) were 0.41 and 0.57, respectively. Conclusions When R_G is more than 1.5 times of M+R_T value and the gating beam on phase contains the phases in the rapid rise and fall of the respiratory curve, the possibility of the off-target during radiotherapy is significantly increased.
		2022 Vol. 31 (7): 605-610 [Abstract] ( 86 ) [HTML 1KB] [ PDF 0KB] ( 0 )

	611	Risk analysis of brain metastases in limited-stage small cell lung cancer (LS-SCLC)achieving complete remission after thoracic radio-chemotherapy
		Shen Bin, Liu Jianjiang, Qiu Guoqin, Ji Yongling, Du Xianghui, Yang Yang
		Objective Small cell lung cancer (SCLC) is a highly malignant tumor with a high risk of brain metastasis (BMs). The purpose of this study was to evaluate the clinical factors affecting the occurrence of BMs in patients with stage IIB-IIIB SCLC who achieved complete remission (CR) after thoracic radio-chemotherapy. Methods Clinical data of 191 patients with stage IIB-IIIB SCLC who achieved CR after thoracic radio-chemotherapy in Zhejiang Cancer Hospital from January 2009 to April 2016 were retrospectively analyzed. Common clinical factors related to the risk of BMs, including gender, age, thoracic radiotherapy dose, combined mode of radiotherapy and chemotherapy, pretreatment serum NSE and LDH, whether PCI was performed, TMN stage and PS score, were analyzed using log-rank method for univariate analysis, COX regression method for multivariate analysis and Kaplan-Meier method to plot the survival curve. Results Univariate analysis showed that pretreatment LDH level≥240IU, pretreatment NSE ≥17 ng/ml and no PCI were positively correlated with the risk of BMs (all P<0.05). Multivariate analysis showed that the risk of BMs was only positively correlated with pretreatment LDH≥240IU [HR: 1.90, 95%CI(1.07-3.37), P=0.029], and no PCI [HR:2.08, 95%CI(1.17-3.72), P=0.013]. Conclusions Pretreatment serum LDH levels provide important value for predicting the risk of BMs in patients with stage IIB-IIIB SCLC who achieve CR after thoracic radio-chemotherapy.
		2022 Vol. 31 (7): 611-616 [Abstract] ( 82 ) [HTML 1KB] [ PDF 0KB] ( 0 )

	622	Clinical application of new self-designed implanting applicator in vaginal three-dimensional intracavitary brachytheraypy after hysterectomy for gynecological cancer
		Ling Baozhen, Mai Miaoqing, Cao Xinping, Ye Weijun, Ouyang Yi, Guo Xuan
		Objective Investigate the safety and feasibility of using the new self-designed implanting applicator in vaginal three-dimensional intracavitary brachytherapy after hysterectomy for gynecological cancer, and to explore the clinical value of the self-designed implanting applicator. Methods Sixty-two gynecological cancer patients who underwent brachytherapy in Sun Yat-sen University Cancer Center were selected in this study. Each patient received three-dimensional intracavitary brachytherapy because of the indication of postoperative radiotherapy. Each patient was treated with different types of self-designed implanting applicators according the condition of postoperative vagina,and the vaginal tube and implant needle were placed in the template according to the preset channnel. Based on the actual CT images, the high-risk clinical target volume (HR-CTV), and organs at risk were defined according to unified target area delineation criteria and then the brachytherapy plan was conducted. The prescription dose of high-risk clinical target volume (HR-CTV) was 5.5 Gy/time. The parameters such as target area, organs at risk volume and irradiated dose were evaluated by DVH diagram. Results Sixty-two patients successfully completed brachytherapy under the guidance of self-designed implanting applicator. A total of 140 implantation treatments were performed. The total average dose of HR-CTV D90% was (575.48±22.30) cGy, the mean dose D_2cm³ of bladder, rectum and sigmoid colon were (328.69±102.71), (369.14±46.59) and (27.28±71.27) cGy, the small intestine did not drop the target area, so there was no statistics. There was statistical significance between target volume and organs at risk dose (P<0.05). Conclusions The new self-designed implanting applicator has obvious clinical advantages in vaginal three-dimensional intracavitary brachytherapy after hysterectomy for gynecological cancer, meets the requirements of the preset planning dose,and it is sample to operate and highly safe,which indicated a bright future of the clinical application.
		2022 Vol. 31 (7): 622-627 [Abstract] ( 70 ) [HTML 1KB] [ PDF 0KB] ( 0 )

Abdominal Tumors

	617	Clinical efficacy of postoperative radiotherapy using shrinking field for patients with extremity soft tissue sarcoma
		Chen Changshun, Yang Rui, Li Dongbo, Fu Chunpeng, Zhang Ruiping
		Objective To investigate the effectiveness of postoperative radiotherapy using shrinking field for patients with extremity soft tissue sarcoma (STS), mainly focusing on the local control rate and adverse events. Methods Clinical data of 49 extremity STS patients who received postoperative intensity-modulated radiotherapy in the First Hospital of Tsinghua University from October 2017 to March 2021 were retrospectively analyzed. Target volumes were contoured on CT and MRI fusion images. The tumor bed was defined as GTV_tb, with 3 cm expansion in the longitudinal direction and 1.5 cm expansion in the radial direction to construct CTV (the target volume should be properly repaired according to the anatomical barrier, and the edema area around the tumor should be included). GTV_tb and CTV were expanded in all directions by 0.5 cm to construct PTV1 and PTV2 respectively, at a dose of 95%PTV1 63-66 Gy, 95%PTV2 50-56 Gy,1.8-2.0 Gy/f. The dose of surgical volume should be given at 70 Gy for patients who had a microscopic positive margin. Results The median follow-up time was 32.1 months (7.9-45.6 months). The 3-year local failure-free survival (LFFS), overall survival (OS)and distant metastasis-free survival (DMFS) were 91.7%,77.6% and 71.5%, respectively. Univariate analysis showed that patients with a microscopic positive margin were more likely to develop local recurrence (P<0.05). The incidence of grade 2 or above wound complications, joint stiffness, fracture, edema and skin fibrosis were 2%, 4.1%, 2%, 8.2% and 26.5%, respectively. Conclusions Postoperative radiotherapy with shrinking field provides excellent local control rate and low incidence of late adverse events in patients with extremity STS.
		2022 Vol. 31 (7): 617-621 [Abstract] ( 88 ) [HTML 1KB] [ PDF 0KB] ( 0 )

Physics·Technique·Biology

	628	Analysis of the registration deviation between CT and CBCT images with different breathing rates and motion amplitudes in the state of free breathing
		Wei Xing, Xu Xin, Bai Long, Gong Pan, Zhong Renming
		Objective To quantify the registration deviation between CT and cone-beam computed tomography (CBCT) images with different breathing rates and motion amplitudes under free breathing state. Methods Using the QUASAR respiratory motion phantom, breathing rate and motion amplitude in the superior-inferior (SI) direction were changed to simulate free breathing motion under different states. The CT and CBCT images were acquired under different breathing rates and motion amplitudes, and static states, then the registration errors between CT and CBCT images and CT target volume were obtained and subject to quantitative analysis. Results Using the static CT image as a reference, the changes in breathing rate exerted no significant effect on the registration error when the motion amplitude was constant. When the motion amplitude was 0.5, 1.0, 2.0, and 3.0 cm, the average registration errors were (0.213±0.020), (0.351±0.009), (0.654±0.010), and (0.972±0.022) cm, respectively. When the motion amplitude was 0.5 and 1.0 cm, the CT target volume varied from -16.92% to 18.78%. When the motion amplitude was 2.0 and 3.0 cm, the CT target volume changed from -16.44% to 81.78%. Conclusions The changes in breathing rate under free-breathing state has no significant effect on the registration error between CBCT and CT images. When the motion amplitude is 0.5 and 1.0 cm, the CT target volume changes and the registration errors are small. When themotion amplitude is 2.0 and 3.0 cm, the registration errors exceed 0.5 cm and the CT target volume changes may exceed 20%.
		2022 Vol. 31 (7): 628-632 [Abstract] ( 79 ) [HTML 1KB] [ PDF 0KB] ( 0 )

	633	Application of 3D printed personalized breast bracket in IMRT for breast cancer
		Tang Xiaoyan, Ye Rong, Huang Fasheng, Yan Yuying, Zhang Weisha, Huang Zuoyun, Ling Rui
		Objective By comparing the positioning errors caused by 3D printed personalized breast bracket and common headrest in intensity-modulated radiation therapy (IMRT), the fixation effect of 3D printed personalized breast bracket in IMRT was analyzed. Methods Thirty-two breast cancer patients from January to July 2021 were randomly divided into a the 3D printed breast bracket group and common headrest group. All patients in two groups were kept in supine position, head tilted to the healthy side, the affected hand held the grip bar on the same side of the horizontal bar, the healthy hand held the opposite side of the vertical bar, and the chest and mandible were fixed with thermoplastic film. CBCT scan was performed weekly, and gray level registration was carried out according to the three registration regions of interest: breast or chest wall field, supraclavicular and inferior field, and axillary field. The positioning errors in the left and right, head and foot, abdomen and back directions were analyzed between two groups. Results In the 3D printed breast bracket group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, head and foot, abdomen and back directions were (1.75±1.26), (1.77±1.11) and (1.70±1.08) mm, (1.75±1.25), (1.72±1.09) and (1.70±1.05) mm,(1.86±1.34), (2.14±2.13) and (1.66±1.19) mm, respectively.In the common headrest group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, the head and feet, the abdomen and back directions were (2.54±1.84), (2.73±3.62) and (2.18±2.45) mm, (3.25±2.02), (3.52±2.26) and (2.62±2.83) mm, (3.25±2.05), (4.44±2.90) and (3.10±3.18) mm, respectively.The positioning errors significantly differed between two groups (all P<0.05). Conclusions The positioning error of 3D printed personalized breast bracket fixation is less than that of common headrest fixation. The positioning consistency of 3D printed personalized breast bracket in the three target areas of breast or chest wall field, supraclavicular and inferior field and axillary field is better than that of common headrest.
		2022 Vol. 31 (7): 633-637 [Abstract] ( 90 ) [HTML 1KB] [ PDF 0KB] ( 0 )

	638	Effect of shRNA silencing of Sp1on radiosensitivity of glioma cells
		Wang Qiqi, Zeng Jiayu, Li Qiang, Liu Xiongxiong
		Objective To evaluate the effect of down-regulation of Sp1 expression on the radiosensitivity of glioma cells. Methods The oligonucleotide sequence encoding shRNA was designed and synthesized, and cloned into LV3 (H1/GFP & Puro) vector to construct the recombinant. U251 and U87 cells were infected with recombinant lentivirus, then the stably-transfected cell lines were obtained by puromycin screening. The expression levels of Sp1 mRNA and protein were detected by RT-PCR and Western blot. Cell survival was detected by clonal survival assay, cell cycle was determined by flow cytometry, and DNA damage was measured by immunofluorescence assay, respectively. Results At 72 h after infection, high expression of Sp1 lentiviral vector was observed in two cell lines under fluorescence microscope. RT-PCR and Western blot confirmed that the expression levels of Sp1 mRNA and protein were significantly down-regulated in both transfected cells (both P<0.01) and the silencing rates of Sp1 were above 90%. The sensitization enhancement ratio (SER) of shRNA-U251 and shRNA-U87 cells at 10% cell survival level were 1.39 and 1.18, respectively. After irradiation, the G₂/M phase ratio and the number of γ-H2AX foci in two Sp1 knockout groups were significantly increased. Conclusions hRNA silencing of Sp1 increases the G₂/M phase arrest induced by X-ray, aggravates the degree of DNA double-strand breaks, and improves the radiosensitivity of glioma cells.
		2022 Vol. 31 (7): 638-642 [Abstract] ( 68 ) [HTML 1KB] [ PDF 0KB] ( 0 )

	643	Mechanism of the role of NDUFAF4 in increasing radiation resistance of hepatocellular carcinoma by activating Wnt/β-catenin signaling pathway
		You Jie, Wang Xiumin, Meng min, Huang Hongchun, Chen Yujun
		Objective To analyze the association between the expression of ubiquinone oxidoreductase complex assembly factor 4 (NDUFAF4) and clinical prognosis of patients with hepatocellular carcinoma (HCC), evaluate the effect of NDUFAF4 on the radiosensitivity of human HCC cell lines, and unravel the underlying mechanism. Methods The online database and HCC tissue samples were used to investigate the expression of NDUFAF4, and the correlation between NDUFAF4 expression level and clinical prognosis. The si-NDUFAF4 plasmid which down-regulated the expression level of NDUFAF4 was transferred into HepG2 and Huh7 cells. The radiosensitivity of HCC cell lines was detected by clone formation experiment. Nude mice were prepared for tumor-bearing experiment. The β-catenin level was detected by immunofluorescent staining. The expression levels of E-cadherin and N-cadherin proteins were determined by Western blot. Results Bioinformatics results confirmed that NDUFAF4 was significantly up-regulated in HCC tissues, and the higher the expression level, the worse the patients' clinical prognosis (P<0.05). The expression level of NDUFAF4 in HCC tissues was significantly higher than that in the adjacent tissues. Clone formation experiment confirmed that knockdown of NDUFAF4 significantly decreased the survival rate of HCC cells (P<0.01). In vivo experiment showed that knockdown of NDUFAF4 could prevent the proliferation of HCC cells and down-regualte the expression levels of β-catenin and Ki-67. Knockdown of NDUFAF4 significantly down-regulated the expression level of β-catenin protein in the nucleus of HCC cell lines, suggesting that NDUFAF4 could activate the WNT/β-catenin signaling pathway. Knockdown of NDUFAF4 significantly up-regulated the expression level of E-cadherin and down-regulated that of N-cadherin. Conclusions Knockdown of NDUFAF4 can significantly enhance the radiosensitivity of HCC cell lines by inhibiting the WNT/β-catenin signaling pathway. The expression level of NDUFAF4 is intimately correlated with clinical prognosis. NDUFAF4 can be considered as a new target for lowering the radiation resistance of HCC.
		2022 Vol. 31 (7): 643-648 [Abstract] ( 86 ) [HTML 1KB] [ PDF 0KB] ( 0 )

Review Articles

	649	Diagnosis and treatment of cervical lymph metastasis carcinoma from unknown primary tumor
		He Meilin, Yi Junlin
		Cervical lymph metastasis carcinoma from unknown primary tumor (CCUP) accounts for 3% to 5% of all malignant tumors of head and neck. With the development of PET-CT, molecular pathology, endoscopy and other auxiliary examinations and the advancement of radiotherapy technology, the diagnostic and treatment levels of CCUP have been gradually improved. Surgery and radiotherapy are the most important treatment methods of CCUP. However, due to its low incidence and heterogeneity, prospective clinical trial data are still lacking. Hence, the optimal therapy of CCUP remains highly controversial. In this article, research progresses on the diagnosis and treatment of CCUP in recent years were reviewed.
		2022 Vol. 31 (7): 649-654 [Abstract] ( 103 ) [HTML 1KB] [ PDF 0KB] ( 0 )

	655	Progress on standardized nutrition therapy for head and neck cancer during the peri-radiotherapeutic period
		Gu Ying, Zou Li, Huang Yiting, Feng Yuezhen, Tian Ye, Fang Chen
		Malnutrition is a common complication of cancer patients, and solving nutrition problems is still one of the challenging tasks in clinical practice. The incidence of malnutrition in head and neck cancer patients during the peri-radiotherapeutic period is high, which is not only related to disease-mediated metabolic disorders, complications and psychological factors, but also associated with the toxic and side effects induced by radiotherapy. Malnutrition will reduce the tolerance, accuracy, and therapeutic effects of radiotherapy, which in turn lowers the quality of life and even adversely affects the prognosis of disease. Medical nutrition therapy can improve the nutritional status of the body, ensure smooth progress of radiotherapy, and improve the efficacy of comprehensive cancer treatment. It is necessary and urgent to deliver standardized nutrition therapy and management of head and neck cancer patients during the peri-radiotherapeutic period. Nutritional risk screening, nutritional assessment, and acute radiation injury assessment are required to develop an individualized nutrition treatment plan and make dynamic adjustment. In this article, relevant literature of nutrition therapy for head and neck radiotherapy at home and abroad was summarized, and the standardized nutrition therapy for head and neck cancer patients during the peri-radiotherapeutic period was reviewed.
		2022 Vol. 31 (7): 655-659 [Abstract] ( 67 ) [HTML 1KB] [ PDF 0KB] ( 0 )

	660	Research progress on the application of stereotactic body radiation therapy in the treatment of early-stage small cell lung cancer
		Xiao Xi, Wang Jianyang, Bi Nan
		Small cell lung cancer (SCLC) is a poorly differentiated, rapidly aggressive and highly chemoradio-sensitive malignancy. Recent research finds that stereotactic body radiation therapy (SBRT) is well tolerated in the treatment of early-stage SCLC with excellent locoregional control rates. This paradigm could offer comparable overall survival and cancer-specific survival with surgery or conventional concurrent chemoradiotherapy. Presently, SBRT has become one of the standard treatment options for patients with stage I-IIA SCLC. Due to the enlightened role of SBRT in the treatment of SCLC, this review aims to discuss the clinical research to date in the application status, clinical value and developing tendency of SBRT in the treatment of patients with early-stage SCLC.
		2022 Vol. 31 (7): 660-665 [Abstract] ( 69 ) [HTML 1KB] [ PDF 0KB] ( 0 )

	666	Clinical value and research progress on prophylactic cranial irradiation in small cell lung cancer under advanced diagnosis and treatment technology
		Yan Ke, Shen Wenbin, Zhu Shuchai
		Small cell lung cancer (SCLC) is highly malignant, aggressive and prone to brain metastasis. Several guidelines recommend prophylactic cranial irradiation (PCI) as the standard treatment for SCLC patients who have achieved complete remission after initial systemic treatment. However, in the modern era, magnetic resonance imaging (MRI) has been commonly applied in the diagnosis of brain metastasis, while radiotherapy combined with immunotherapy and molecular targeted therapy are widely adopted in the treatment of lung cancer. The value of PCI in SCLC has been questioned and challenged. In addition, the application of hippocampal avoidance and drugs to reduce the damage of neurocognitive function after PCI has also become a research hotspot. In this article, the research progress on PCI was reviewed with the latest literature, aiming to provide reference for selecting the most suitable individualized treatment for patients receiving PCI.
		2022 Vol. 31 (7): 666-670 [Abstract] ( 67 ) [HTML 1KB] [ PDF 0KB] ( 0 )

	671	Research progress on application of artificial intelligence in radiotherapy for gynecological malignancy
		Du Ming, Liu Xiaoxia, Xu Congjian, Zhang Xiaoyan
		The gynecological malignancy has a high incidence and mortality. More efficient treatment methods still need to be explored to improve the survival benefits. Artificial intelligence (AI) aims to intelligently process the original problems by simulating the thinking way of human brain. It has obtained significant progress in gynecological malignancy, with great potential in the field of cancer diagnosis and treatment. This paper reviews the application of AI in the diagnosis and treatment of gynecological malignancy, and mainly introduces the research progress on AI in the radiotherapy. This paper mainly focuses on the key issues such as automatic delineation, dose prediction, radiotoxicity prediction and efficacy prediction, and discusses the current benefits and limitations of AI in radiotherapy of gynecological malignancy.
		Guide:
		2022 Vol. 31 (7): 671-674 [Abstract] ( 91 ) [HTML 1KB] [ PDF 0KB] ( 0 )

中华放射肿瘤学杂志

News

More.....

Cooperation unit

友情链接

China Association for
　Science and Technology

Chinese Medical Association

Cancer Hospital of Chinese
　Academy of Medical
　Sciences Department of
　Radiation Oncology

Chinese Anti-Cancer
　Association

Chinese Journal of Lung
　Cancer

Cqvp

CNKI

Wanfang Data

More....