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   74191篇
  免费   6665篇
  国内免费   158篇
耳鼻咽喉   675篇
儿科学   2720篇
妇产科学   2466篇
基础医学   8918篇
口腔科学   882篇
临床医学   11378篇
内科学   13604篇
皮肤病学   1169篇
神经病学   7175篇
特种医学   1727篇
外科学   8341篇
综合类   787篇
现状与发展   1篇
一般理论   98篇
预防医学   9556篇
眼科学   1295篇
药学   4906篇
中国医学   86篇
肿瘤学   5230篇
  2023年   757篇
  2022年   961篇
  2021年   2180篇
  2020年   1403篇
  2019年   2190篇
  2018年   2439篇
  2017年   1918篇
  2016年   2117篇
  2015年   2169篇
  2014年   3102篇
  2013年   4146篇
  2012年   5719篇
  2011年   5743篇
  2010年   3243篇
  2009年   2896篇
  2008年   4700篇
  2007年   4697篇
  2006年   4369篇
  2005年   4128篇
  2004年   3715篇
  2003年   3253篇
  2002年   2962篇
  2001年   774篇
  2000年   675篇
  1999年   756篇
  1998年   672篇
  1997年   546篇
  1996年   517篇
  1995年   488篇
  1994年   408篇
  1993年   365篇
  1992年   484篇
  1991年   406篇
  1990年   437篇
  1989年   420篇
  1988年   336篇
  1987年   332篇
  1986年   352篇
  1985年   335篇
  1984年   307篇
  1983年   300篇
  1982年   219篇
  1981年   234篇
  1980年   187篇
  1979年   236篇
  1978年   219篇
  1976年   173篇
  1975年   159篇
  1974年   153篇
  1973年   164篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
53.
A 19-item survey instrument was designed and mailed by the Infectious Diseases Society of America to its membership to determine the media preferred by infectious diseases physicians for continuing medical education on general topics and on antimicrobial resistance. The objective of the survey was to offer the developers of educational programs knowledge on which to base more-effective ways to deliver educational materials to physicians in this specialty.  相似文献   
54.
55.
Diarrhetic shellfish poisoning (DSP) is a serious and globally widespread phytoplankton-related seafood illness. Although DSP is rarely life-threatening, it causes incapacitating diarrhea and vomiting with no known medical treatments. In addition, phytoplankton producing DSP toxins have been identified in temperate coastal waters worldwide, and their numbers may be increasing as a result of coastal eutrophication. The toxic effects of the major DSP toxins, okadaic acid and dinophysistoxin-1 (35-methylokadaic acid), appear to originate from their inhibitory activity against a family of structurally related serine/threonine protein phosphatases (PSPases). In particular, the inhibition of essential PSPases (e.g. PP1 and PP2A) has catastrophic consequences in most eukaryotic cells. Exploiting the potent inhibitory property of the DSP toxins, we have developed an enzyme-based assay (PP2A assay) capable of detecting both okadaic acid and dinophysis- toxin-1 in nanogram amounts. The assay employs purified PP2A, which has an extremely high affinity for both DSP toxins. This provides the PP2A assay with a level of sensitivity comparable to, or surpassing, that of most monoclonal antibody probes. To evaluate the PP2A assay as a means of detecting contaminated shellfish, a series of spike recovery experiments was conducted. The findings from these studies suggest that the PP2A assay has the potential for development into a rapid and relatively simple method for detecting PSPase inhibitors in crude extracts produced from shellfish.  相似文献   
56.
Using the buttock flap in 29 white Yorkshire pigs, blood flow and O2 consumption were measured at dermal temperatures between 35 degrees C and 15 degrees C. Flow was measured with an electromagnetic flowmeter and O2 consumption was calculated as the product of blood flow and the difference in flap A-VO2. Baseline flow was 6.6 +/- .9 (SE) ml/100 g/min at 35 degrees C and 3.1 +/- .02 (SE) ml/10 g/min at 15 degrees C. Blood flow through the flap stopped completely at a dermal temperature of 14 degrees C. Oxygen consumption was 0.16 +/- .02 (SE) ml/100 g/min at 35 degrees C and 0.04 +/- 0.01 (SE) ml/100 g/min at 15 degrees C. At 20 degrees C blood flow was 4.3 ml/100 g/min and metabolism was .04 ml/100 g/min. In other words, blood flow was 65% of baseline, while O2 consumption was only 25% of baseline. The therapeutic effect of local cooling at 20 degrees C deserves further investigation. The cessation of flow at 14 degrees C may be caused by increased plasma viscosity.  相似文献   
57.
58.
59.
60.
Scurvy is a nondiscriminatory disease process resulting from a nutritional deficiency of ascorbic acid (vitamin C). The severe vitamin deficiency produces a breakdown in the cellular structure of the body. This case report describes a middle-age woman with a history of edema, bruising of the lower extremities, anemia, and severe periodontal disease. Her presentation and medical history are classic for the signs of scurvy. Scurvy is now only uncommonly seen in developed countries, but there are still vulnerable populations whose nutritional status can lead to scurvy. The aim of this report is to help the clinician identify and treat scurvy, a disease that was once feared for its high mortality but is now easily treatable, even in cases that have progressed to multiple organ dysfunction and failure.  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