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   83658篇
  免费   5933篇
  国内免费   1928篇
耳鼻咽喉   1226篇
儿科学   1512篇
妇产科学   2709篇
基础医学   11302篇
口腔科学   1596篇
临床医学   8401篇
内科学   15597篇
皮肤病学   1718篇
神经病学   5471篇
特种医学   3688篇
外国民族医学   6篇
外科学   11272篇
综合类   4377篇
现状与发展   10篇
一般理论   23篇
预防医学   4704篇
眼科学   1922篇
药学   6997篇
  21篇
中国医学   1883篇
肿瘤学   7084篇
  2023年   683篇
  2022年   1743篇
  2021年   2922篇
  2020年   1640篇
  2019年   2175篇
  2018年   2657篇
  2017年   2011篇
  2016年   2216篇
  2015年   3275篇
  2014年   3951篇
  2013年   4556篇
  2012年   6677篇
  2011年   6431篇
  2010年   3956篇
  2009年   3399篇
  2008年   4656篇
  2007年   4681篇
  2006年   4367篇
  2005年   3936篇
  2004年   3565篇
  2003年   3349篇
  2002年   2942篇
  2001年   2288篇
  2000年   2033篇
  1999年   1651篇
  1998年   662篇
  1997年   540篇
  1996年   478篇
  1995年   434篇
  1994年   388篇
  1993年   294篇
  1992年   814篇
  1991年   673篇
  1990年   624篇
  1989年   578篇
  1988年   493篇
  1987年   498篇
  1986年   411篇
  1985年   342篇
  1984年   259篇
  1983年   225篇
  1982年   135篇
  1981年   148篇
  1980年   108篇
  1979年   233篇
  1978年   189篇
  1977年   125篇
  1976年   134篇
  1975年   121篇
  1974年   121篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
Summary Fifty-five patients with metastatic non-small cell lung cancer (NSCLC) were entered into this phase II randomized study for evaluating three new agents: gallium nitrate, amonafide and teniposide. The patients had to have ECOG performance status 0 or 1, no prior chemotherapy, and adequate hematological, hepatic and renal functions. Forty-seven patients were eligible and evaluable. Fourteen were randomized to receive gallium nitrate, 18 to amonafide and 15 to teniposide. Seventy-four percent of eligible patients were male. The majority of patients (89%) had an ECOG performance status 1. ECOG grade 4 toxicity occurred twice in patients on gallium nitrate, seven times on amonafide and 18 times on teniposide. The cause of death was attributed to amonafide in one patient (from sepsis) and to teniposide in two patients (due to infection and leukopenia). There was no objective response in all the patients entered. The overall survival times ranged from 2 weeks to 156 weeks with a median of 23 weeks. There were no survival differences among the three treatment arms. We conclude that gallium nitrate, amonafide and teniposide are inactive in metastatic NSCLC and do not warrant any further testing in this disease.The contents of this study is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute.  相似文献   
44.
Using the polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) analysis, we have examined the highly conserved regions of the p53 gene in 58 biopsy samples of head and neck tumors. Mutations were found in 13/58 (23%) tumor specimens, but not in 6 normal tissues. Ten of 13 mutations were due to single base changes and the remaining 3 were 1- or 8-base deletion mutants. These mutations were clustered in exons 5 and 7 and resulted in amino acid changes. Our results seem to indicate that mutations in the p53 gene contribute to a significant number of cases of the head and neck tumors including 20% of nasopharyngeal carcinoma biopsies. The relationship of Epstein-Barr virus or human papillomavirus and p53 gene mutations in this group of cancers was also analyzed and discussed.  相似文献   
45.
Monochloramine (NH2Cl), a granulocyte-derived reactive oxygen metabolite (ROM), increases short-circuit current (Isc) in cultured T84 monolayers in a concentration-dependent manner up to nonlethal concentrations of 75 microM. Isc increases slowly after NH2Cl, reaching a peak value of 18 +/- 2 microA/cm2 20 min after addition. The Isc changes are persistent (lasting over 20-30 min), depend on medium Cl, and are inhibitable with bumetanide. 36Cl flux studies demonstrated that NH2Cl increases serosa-to-mucosa flux of Cl without changing mucosa-to-serosa flux, consistent with stimulation of electrogenic Cl secretion. Isc responses to NH2Cl, but not PGE2, are dependent on medium calcium. As demonstrated in fura-2-loaded T84 cells, NH2Cl increases free cytosolic calcium by influx of extracellular Ca2+ and by release of Ca2+ from endogenous stores. However, NH2Cl had no effect on phosphatidylinositol metabolism or cyclic nucleotide levels. We conclude that ROM directly stimulate electrolyte secretion, an effect in part mediated by increases in cytosolic Ca2+, possibly through increasing Ca2+ permeability of cellular membranes.  相似文献   
46.
Quality of life in adult survivors of lung,colon and prostate cancer   总被引:22,自引:0,他引:22  
In a cross-sectional study design, a disease free sample of 57 lung, 117 colon, and 104 prostate cancer survivors who represented short, intermediate and long-term survivors completed a detailed assessment of quality of life (QOL) and rehabilitation needs using the CAncer Rehabilitation Evaluation System (CARES). Demographic and medical data, social support, and a global QOL rating were also assessed. Lung cancer patients showed no differences in QOL with respect to their period of survival. QOL improved for survivors of colon cancer as they lived for longer periods, but declined with time for survivors of prostate cancer. The best predictor of QOL for all groups was KPS, although other variables such as type of hospital, gender, and work status were predictive for survivors of colon cancer. For survivors of prostate cancer comorbidity with other medical illnesses, time since diagnosis and comorbidity due to psychiatric difficulties were predictive of QOL. All groups had significant rehabilitation problems in the domains of physical, psychosocial, sexual, medical interaction, and marital relationships. Lung cancer survivors had more problems than the other cancer survivors. We conclude that patients who survive cancer do not return to a state of normal health. They demonstrate a variety of difficulties with which they must cope as they continue to survive. Greater efforts need to be made early in diagnosis and treatment to understand rehabilitation problems and target interventions in the hope of reducing later sequelae.Currently in private practice, Glendale, CaliforniaC. A. C. Schag was supported in part by Veterans Administration Health Research and Development Grant 83-002 and in part by Cares Consultants, 2210 Wilshire Blvd., Suite 359, Santa Monica, CA 90403.Address requests for Information about CARES to: CARES Consultants, 2210 Wilshire Blvd., Suite 359, Santa Monica, CA 90403, USA. Tel: (+1) 310-450-7410; Fax: (+1) 310-399-0016  相似文献   
47.
48.
Laparoscopic nephrectomy was performed in 15 male pigs, the procedure was successful in 14. Extraction of the intact kidney through a 5-cm lower abdomen incision was done in 7 animals; complete destruction and evacuation of the kidney was accomplished by a round-knife suction device through a 1-cm port in another 7 pigs. Grossly, the specimen consisted of sausage-like tubular renal tissue and a small amount of tissue debris. Pathology revealed that the glomerular and tubular structures were well preserved, no interstitial hematoma could be found. Four ports were usually used, one 1-cm umbilical camera port, one 0.5-cm port for ureter traction, and two 1-cm working ports along the midclavicular line. All the pigs recovered uneventfully. The average operation time was 3 h 20 min. The application of endo-GIA (United States Surgical Corporation) for renal hilum reduced the operative time to 2 h 20 min. Complications included renal vein tear during endoclip application and cutting in the first case, mild subcutaneous emphysema in 2 cases. This first pig received exploratory laparotomy for the repair and ligation of the renal vein. No more major complications occurred with increasing experience. From this porcine experiment, we conclude that the combination of laparoscopy, a tissue destroyer and an endobag for the entrapment of kidney seem to be a promising technique for clinical nephrectomy.  相似文献   
49.
C1: molecular interactions with activating systems.   总被引:1,自引:0,他引:1  
R B Sim  K B Reid 《Immunology today》1991,12(9):307-311
The molecular events controlling complement activation have been gradually unravelled over the past three decades, stimulated by improved isolation procedures and a better understanding of the roles of individual proteins. In this review, Bob Sim and Ken Reid examine the interactions between C1q and its numerous ligands in the initiation of the classical pathway cascade.  相似文献   
50.
目的研究采用自体静脉管套入吻合口并注入脑细胞生长肽的方法,对面神经损伤后功能恢复的影响.方法吻合神经断端后用自体静脉管套入吻合口并注入脑细胞生长肽.分析肌电图和观察表情肌功能恢复,比较两种方法对损伤的面神经功能恢复的影响.结果自体静脉管套入吻合口并注入脑细胞生长肽的方法,比传统方法表情肌功能恢复时间明显缩短,且一期修复比二期修复功能恢复时间明显缩短,差异具有非常显著性意义(P<0.01).两种方法修复面神经损伤,表情肌功能恢复后检测面神经传导速度差异无显著性意义(P>0.05).结论自体静脉管套入吻合口并注入脑细胞生长肽的方法是一种比较有前途的面神经修复方法.  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