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   2010757篇
  免费   167806篇
  国内免费   7692篇
耳鼻咽喉   27354篇
儿科学   62681篇
妇产科学   56528篇
基础医学   281115篇
口腔科学   57118篇
临床医学   180292篇
内科学   402349篇
皮肤病学   45501篇
神经病学   165209篇
特种医学   82093篇
外国民族医学   431篇
外科学   315081篇
综合类   51419篇
现状与发展   4篇
一般理论   657篇
预防医学   161081篇
眼科学   45351篇
药学   144224篇
  5篇
中国医学   3543篇
肿瘤学   104219篇
  2018年   19334篇
  2016年   18022篇
  2015年   20516篇
  2014年   28855篇
  2013年   43472篇
  2012年   54870篇
  2011年   58554篇
  2010年   35854篇
  2009年   34618篇
  2008年   54975篇
  2007年   59097篇
  2006年   60003篇
  2005年   58294篇
  2004年   56190篇
  2003年   54472篇
  2002年   51924篇
  2001年   91041篇
  2000年   93456篇
  1999年   78438篇
  1998年   24019篇
  1997年   21626篇
  1996年   22343篇
  1995年   22035篇
  1994年   20720篇
  1993年   19530篇
  1992年   65854篇
  1991年   64354篇
  1990年   62256篇
  1989年   59499篇
  1988年   55502篇
  1987年   54674篇
  1986年   51652篇
  1985年   50046篇
  1984年   38464篇
  1983年   32577篇
  1982年   20602篇
  1981年   18760篇
  1980年   17662篇
  1979年   36406篇
  1978年   26385篇
  1977年   22266篇
  1976年   20438篇
  1975年   21755篇
  1974年   26182篇
  1973年   25074篇
  1972年   23552篇
  1971年   21675篇
  1970年   20242篇
  1969年   19309篇
  1968年   17721篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Analyzing functional species’ characteristics (species traits) that represent physiological, life history and morphological characteristics of species help understanding the impacts of various stressors on aquatic communities at field conditions. This research aimed to study the combined effects of pesticides and other environmental factors (temperature, dissolved oxygen, dissolved organic carbon, floating macrophytes cover, phosphate, nitrite, and nitrate) on the trait modality distribution of aquatic macrofauna communities. To this purpose, a field inventory was performed in a flower bulb growing area of the Netherlands with significant variation in pesticides pressures. Macrofauna community composition, water chemistry parameters and pesticide concentrations in ditches next to flower bulb fields were determined. Trait modalities of nine traits (feeding mode, respiration mode, locomotion type, resistance form, reproduction mode, life stage, voltinism, saprobity, maximum body size) likely to indicate pesticides impacts were analyzed. According to a redundancy analysis, phosphate -and not pesticides- constituted the main factor structuring the trait modality distribution of aquatic macrofauna. The functional composition could be ascribed for 2–4 % to pesticides, and for 3–11 % to phosphate. The lack of trait responses to pesticides may indicate that species may have used alternative strategies to adapt to ambient pesticides stress. Biomass of animals exhibiting trait modalities related to feeding by predation and grazing, presence of diapause form or dormancy, reproduction by free clutches and ovoviviparity, life stage of larvae and pupa, was negatively correlated to the concentration of phosphate. Hence, despite the high pesticide pollution in the area, variation in nutrient-related stressors seems to be the dominant driver of the functional composition of aquatic macrofauna assembly in agricultural ditches.  相似文献   
62.
63.
64.
65.
66.
67.
68.
The current situation in which the humanities are disparaged affects all university disciplines, including nursing, in whose historical evolution the humanities have always been present in one form or another. Looking beyond this disrepute, this study proposes that nursing renew its attention to classical philosophy. Specifically, it invites a close reading of Xenophon's Anabasis and Plato's Meno, to get three related goals: to show how the use of ancient texts are very valuable tools for the philosophical initiation of nursing students and can help them reflect on their choice of nursing as a practical activity; to reflect on the problem of virtue and the nature of the good life; and to show how the interaction with ancient texts allows students to reflect on questions and issues of life, theirs and others, that are not open to investigation through a purely scientific method. Consequently, both Anabasis and Meno readings strengthen the intellectual relationship between philosophy and nursing, enabling the latter to delve deeper into the key questions of its own thought as a discipline.  相似文献   
69.
Obesity Surgery - Laparoscopic sleeve gastrectomy (LSG) is increasingly playing a key role in obesity management. Such operations, however, carry complications sometimes including leaks. The...  相似文献   
70.
Lasers in Medical Science - Studies reported the harmful effects of 2,4-D on body tissues, provoking changes in the anatomy and physiology of the kidneys, liver, and testicles. Thus, the objective...  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