首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   12974篇
  免费   962篇
  国内免费   6篇
耳鼻咽喉   343篇
儿科学   588篇
妇产科学   398篇
基础医学   1562篇
口腔科学   424篇
临床医学   1246篇
内科学   2451篇
皮肤病学   195篇
神经病学   1439篇
特种医学   553篇
外科学   1473篇
综合类   210篇
一般理论   28篇
预防医学   1046篇
眼科学   387篇
药学   660篇
中国医学   10篇
肿瘤学   929篇
  2021年   162篇
  2020年   120篇
  2019年   155篇
  2018年   224篇
  2017年   143篇
  2016年   167篇
  2015年   154篇
  2014年   249篇
  2013年   373篇
  2012年   510篇
  2011年   529篇
  2010年   275篇
  2009年   291篇
  2008年   451篇
  2007年   507篇
  2006年   526篇
  2005年   469篇
  2004年   461篇
  2003年   420篇
  2002年   459篇
  2001年   426篇
  2000年   418篇
  1999年   348篇
  1998年   147篇
  1997年   117篇
  1996年   126篇
  1995年   128篇
  1994年   125篇
  1992年   369篇
  1991年   377篇
  1990年   367篇
  1989年   315篇
  1988年   326篇
  1987年   339篇
  1986年   310篇
  1985年   294篇
  1984年   194篇
  1983年   190篇
  1982年   122篇
  1981年   121篇
  1980年   105篇
  1979年   200篇
  1978年   178篇
  1977年   125篇
  1976年   101篇
  1975年   117篇
  1974年   130篇
  1973年   127篇
  1972年   111篇
  1971年   100篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Sonography detected a paraaortic pulsatile tubular mass in a patient 10 years after “stump” nephrectomy, which was subsequently confirmed as a renal artery-renal vein fistula by computed tomography, angiography, and laparotomy.  相似文献   
92.
Sonography detected a paraaortic pulsatile tubular mass in a patient 10 years after "stump" nephrectomy, which was subsequently confirmed as a renal artery-renal vein fistula by computed tomography, angiography, and laparotomy.  相似文献   
93.
A boy aged 4.5 years with prune-belly syndrome (PBS) and associated urethral stenosis, oligohydramnios, imperforate anus and vesicosigmoid fustula is described. In contrast to the anticipated poor prognosis, vesicostomy and divided transverse colostomy performed after birth followed by prophylaxis of infection and bicarbonate supplementation have resulted in a good outcome. The vesicosigmoid fistula might have served in utero as a natural diversion protecting from pressure-induced renal damage. It is suggested that the main determinant of prognosis in PBS is the presence and degree of kidney dysplasia at birth as reflected by the neonatal renal function after performance of an indicated urinary diversion procedure rather than the presence of severe associated anomalies.Supported in part by grants from the National Institute of Health AM 37223-01 and the Medical School and Graduate School Research Committees of the University of Wisconsin and a Research Career Development Award KO4 AM 00421 (RWC), by the Pearl M. Stetler Foundation (SD) and by a National Kidney Foundation fellowship (IZ)  相似文献   
94.
Epidermal growth factor receptor (EGFR), determined by the Scatchard curve method, was found in 22 cases of a random series of 100 patients with breast carcinoma. Two groups of patients were identified, one (n = 16) with a low concentration (0–50 fm/mg protein) of EGFR but with a high affinity (Kd = 3.2 nM), and the other (n = 6) with a high concentration (90–210 fm/mg protein) of EGFR but with a lower affinity (Kd = 6.3 nM).A significant inverse relationship was found between the presence of EGFR and receptors for estrogen (p<0.001) and progesterone (p = 0.001). EGFR was found in no (0/8) tumors with Grade I histoprognostic grade, 17% (10/58) Grade II, and 38% (11/29) Grade III (p<0.05). EGFR is present therefore in poorly differentiated tumors and associated with other factors of poor prognosis. Ourin vivo analyses confirm results found in tissue culture derived from human breast carcinoma cells.With the technical assistance of J. Barraque.  相似文献   
95.
D-54 MG, a human glioma-derived continuous cell line growing as subcutaneous or intracranial xenografts in athymic mice, was found to be sensitive to the effects of D,L-buthionine-(SR)-sulfoximine, a selective inhibitor of gamma-glutamylcysteine synthetase. Intraperitoneal administration of one dose of buthionine sulfoximine (BSO, 5 mmol/kg) resulted in depletion of total intracellular glutathione to 57 and 47% of control 12 hr, and 73 and 23% of control 24 hr, after BSO in subcutaneous and intracranial xenografts respectively. Concurrent measurement of total glutathione in the contralateral (non-tumor-containing) cerebral hemisphere in mice bearing intracranial D-54 xenografts demonstrated insignificant depletion of glutathione. Multiple doses of BSO, at 12-hr intervals, resulted in further depletion to 27% (s.c.) and 16.5% (i.c.) of control 12 hr following the final dose of BSO. Quantitative analysis of BSO delivery to xenograft and contralateral brain tissue revealed transfer constants, K1, of 15.8-24.1 x 10(-3) and 2.4 x 10(-3) ml.g-1.min-1 for xenograft and "normal" brain respectively. This highly selective depletion of glutathione in neoplastic tissue versus surrounding non-neoplastic host tissue may have therapeutic implications for the rational use of chemotherapeutic and radiotherapeutic intervention.  相似文献   
96.
97.
Summary The ganglioside patterns of medulloblastomas have never been established; in this study we report the ganglioside profile of the human medulloblastoma cell line TE-671 grown as a xenograft in nude mice. Gangliosides were isolated and structurally analyzed by fast atom bombardment mass spectometry following permethylation. Identification of individual gangliosides was also performed by immunostaining of high-performance thin-layer chromatography-separated bands. Total ganglioside levels of 0.20 mol/g of tissue were obtained, consistent with those reported for human glioma cell lines grown as xenografts; predominant monosialogangliosides of TE-671 xenografts were II3--NeuAc-LacCer (GM3) and II3--NeuAc-GgOse3 Cer (GM2) but there were also relatively large proportions of IV3--NeuAc-LcOse4Cer (3-isoLM1), IV3--NeuAc-nLcOse4Cer (3-LM1) and a further ganglioside of the neolactoseries with an extra lactosamine moiety. The only oligosialoganglioside detected was IV3, II3--NeuAc2-GgOse4Cer (GD1a).Abbreviations: The gangliosides have been designated according to Svenerholm [18] GM3 II3--NeuAc-LacCer - GM2 II3--NeuAc-GgOse3Cer - GM1 II3--NeuAc-GgOse4Cer - 3-LM1 IV3--NeuAc-nLcOse4Cer - 3-isoLMI IV3--NeuAc-LcOse4Cer - Fuc-3-isoLMI IV3--NeuAc, III4-Fuc-LcOse4Cer - GD1a IV3, II3--NeuAc2-GgOse4Cer - FAB-MS Fast atom bombardment-mass spectometry - GC-MS gas chromatography-mass spectometry Supported by NC1 RO1 CA11898 to Dr. Bigner and B8803X-00627-24B from the Swedish Medical Research Council to Dr. L. Svennerholm  相似文献   
98.
99.
The clinical and pathological features of 33 previously untreated patients with primary breast sarcoma were retrospectively analysed to evaluate the prognostic significance of histologic variables on survival. The series comprised 17 cystosarcomas phyllodes and 16 stromal sarcomas (excluding angiosarcomas).All tumors were reviewed and classified in similar fashion to extramammary soft tissue sarcomas. In addition, immunohistochemical studies were performed on paraffin sections with a panel of several antibodies directed against cytoskeletal filaments and cellular enzymes; five cases were also examined by electron microscopy.Most tumors were malignant fibrous histiocytoma (21 cases) and fibrosarcoma (6 cases) types. Surgery was the main therapy. Metastasis-free survival rate was significantly correlated only with histological grade, consisting of tumor differentiation, tumor necrosis, and mitotic activity. Courses and survivals of the cystosarcoma and stromal groups were identical, questioning the clinical value of this pathologic distinction. All local recurrence, metastasis, or death occurred within 30 months, though follow-up was much longer.Immunohistochemistry was disappointing for identification of specific histologic sub-types.  相似文献   
100.
PURPOSE: To document the current state of institutional review board (IRB) and conflict of interest committee policies regarding disclosures of financial conflicts of interest to potential research participants, and to use this information to identify and share models for effectively achieving disclosure. METHOD: The authors identified the 123 U.S. academic medical centers that have IRBs and sought their IRB and institutional policies regarding financial conflicts of interest. In February and March 2004, using manual and key word searches, each institution's Web site was searched to identify documents containing information regarding the disclosure of financial conflicts of interest. Letters were sent to 24 institutions that had either no information or incomplete information posted on their Web sites. To assess institutions' guidelines for disclosure, the authors extracted and content coded each institution's information on disclosure. RESULTS: Relevant information was obtained from 120 (98%) academic medical centers (AMCs), of which 57 (48%) mentioned disclosing financial conflicts to potential research participants. Of these 57, 33 (58%) included verbatim language that could be used in informed consent documents. AMCs' recommendations and requirements for disclosure included details of the financial arrangement, administrative management of conflicts of interest, and encouragement of dialogue between the investigator and the potential research participant. CONCLUSIONS: Considerable variability exists concerning the specific information that should be disclosed. Most of the AMCs' policies were consistent with the goal of protection from legal liability. Significant questions remain, however, concerning the goals of disclosure and the most effective methods for achieving those goals.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号