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   3011667篇
  免费   254545篇
  国内免费   28729篇
耳鼻咽喉   40322篇
儿科学   86912篇
妇产科学   74503篇
基础医学   486518篇
口腔科学   78597篇
临床医学   274426篇
内科学   514919篇
皮肤病学   81977篇
神经病学   254300篇
特种医学   116426篇
外国民族医学   203篇
外科学   465221篇
综合类   122127篇
现状与发展   70篇
一般理论   2077篇
预防医学   241454篇
眼科学   69913篇
药学   214408篇
  186篇
中国医学   20149篇
肿瘤学   150233篇
  2022年   30740篇
  2021年   64398篇
  2020年   42249篇
  2019年   63903篇
  2018年   75866篇
  2017年   58629篇
  2016年   63656篇
  2015年   81488篇
  2014年   117598篇
  2013年   181418篇
  2012年   89218篇
  2011年   87219篇
  2010年   120830篇
  2009年   124770篇
  2008年   68558篇
  2007年   69072篇
  2006年   80257篇
  2005年   75721篇
  2004年   74050篇
  2003年   64655篇
  2002年   53824篇
  2001年   82494篇
  2000年   74529篇
  1999年   79999篇
  1998年   65054篇
  1997年   63488篇
  1996年   60104篇
  1995年   55441篇
  1994年   49314篇
  1993年   45845篇
  1992年   50868篇
  1991年   47215篇
  1990年   43794篇
  1989年   44092篇
  1988年   40705篇
  1987年   39500篇
  1986年   37157篇
  1985年   37741篇
  1984年   37226篇
  1983年   34915篇
  1982年   37678篇
  1981年   35783篇
  1980年   33775篇
  1979年   28198篇
  1978年   27461篇
  1977年   26209篇
  1976年   23285篇
  1975年   21275篇
  1974年   20228篇
  1973年   19267篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The distribution in renal tumours of 3-fucosyl-N-acetyl lactosamine has been studied by using the monoclonal antibodies AGF 4.36 and AGF 4.48 and immunoperoxidase methods on tissue sections. Seven of 19 nephroblastomas and 12 of 30 renal cell carcinomas contained the epitope. In nephroblastomas the epitope was found on the terminals of type B tubules in six cases and in one case on the type A or neoplastic tubules. In renal carcinoma the antigen was found on the surface of tumour cells. The results suggest that in kidneys bearing nephroblastomas ureteric bud elements may grow into the tumour from the adjacent kidney.  相似文献   
992.
993.
1. Quantitative properties of neuronal activity related to a visual reaction time task were studied in the monkey prefrontal cortex. The task consisted of an initial waiting phase (3.0-s period), a warning phase (green lamp, a variable period of 1.5-3.5 s), a go phase (red lamp), and a reward phase. 2. A total of 189 task-related neurons showed 233 changes in discharge rates during the warning (n = 86), GO (n = 103), and reward (n = 44) phases of the task. Most of the task-related neurons (145/189, 77%) showed changes during only one of the task phases, and were designated W (warning phase)-type (n = 42), GO (go phase)-type (n = 59), and RE (reward phase)-type (n = 44) neurons. The remainder (n = 44, 23%) showed changes during both the warning and the go phases, and were designated WG (warning and go phase)-type neurons. In each phase, onset latencies, peak latencies, and decay times of each change were measured and compared. 3. The changes during the warning phase (n = 86) were separated into three groups based on decay time; that is, phasic changes (n = 31), phasic-tonic changes (n = 23), and tonic changes (n = 32). Onset latencies and peak latencies were homogeneously distributed, and there were no clear groupings, although phasic and phasic-tonic changes tended to show shorter latencies than tonic changes. 4. The changes during the go phase (n = 103) did not show distinct differences, either in terms of decay time or of latency. The changes during the go phase showed various degrees of coupling to both the visual go signal (GS) and lever-release hand movement. To quantitate the coupling, a value to indicate the degrees of coupling (coupling index) was calculated. The changes coupled more strongly to the GS (cue coupled), those coupled more closely to the lever release (movement coupled), and intermediate changes could be distinguished from each other. The cue-coupled changes showed shorter latencies from the time onset of the GS than the movement-coupled changes, and the intermediate changes showed intermediate latencies. The decay time and the duration of the intermediate changes were longer than those of the cue-coupled changes and the movement-coupled changes. 5. The properties of WG-type neurons were compared with those of W-type and GO-type neurons.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
994.
995.
996.
997.
Nye  Robert A. 《JAMA》2002,288(10):1294-1295
  相似文献   
998.
Neuropsychiatric disturbances are extremely common in Alzheimer’s disease (AD), and represent integral features of the illness, as well as appropriate targets for therapy. We are interested in designing trials aimed at preventing or delaying the emergence of psychopathology in AD. For symptomatic treatment of agitation, mood stabilizers, particularly sodium valproate, have proved to be beneficial in some patients. Since these effects take several weeks to emerge, we considered that they might be dependent on potentially neuroprotective actions of valproate, such as inhibition of apoptosis and slowing of neurofibrillary tangle formation. In this article we present the rationale for testing the neuroprotective potential of valproate experimentally in mouse models of tauopathy and in a clinical trial of patients with AD who lack psychopathology at baseline. Together, these studies will provide important tests of the hypothesis that valproate, either through inhibition of tau phosphorylation or some other mechanism, is a useful therapeutic agent to modify disease progression in AD.  相似文献   
999.
With the increased use of indwelling central venous catheters, increasing numbers of cases of Rhodotorula fungemia have been observed in patients with neoplasia and neutropenia. In most patients with catheter-related Rhodotorula fungemia, the condition has been treated with broadspectrum antibiotics. We report two cases of central venous catheter-related Rhodotorula rubra fungemia that occurred in patients with acute myeloblastic leukemia. Both patients were in a state of neutropenia. One patient was treated with amphotericin B and his central venous catheter was removed, but he died of Klebsiella pneumoniae bacteremia. The other patient was treated with amphotericin B and discharged, with a central venous catheter, after recovery from neutropenia. Although the management of catheter-related Rhodotorula fungemia infections remains controversial, resolution of the underlying disease is more important than catheter removal for recovery from Rhodotorula rubra fungemia. Received: August 22, 2001 / Accepted: October 8, 2001  相似文献   
1000.
This paper reports the proceedings of the discussion panel assigned to look at clinical aspects of quality in emergency medicine. One of the seven stated objectives of the Academic Emergency Medicine consensus conference on quality in emergency medicine was to educate emergency physicians regarding quality measures and quality improvement as essential aspects of the practice of emergency medicine. Another topic of interest was a discussion of the value of information technology in facilitating quality care in the clinical practice of emergency medicine. It is important to note that this is not intended to be a comprehensive review of this extensive topic, but instead is designed to report the discussion that occurred at this session of the consensus conference.  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