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   1427594篇
  免费   115036篇
  国内免费   6364篇
耳鼻咽喉   17436篇
儿科学   46184篇
妇产科学   37985篇
基础医学   194693篇
口腔科学   36792篇
临床医学   126279篇
内科学   296774篇
皮肤病学   32327篇
神经病学   119596篇
特种医学   59749篇
外国民族医学   274篇
外科学   226011篇
综合类   32254篇
现状与发展   2篇
一般理论   414篇
预防医学   114873篇
眼科学   29048篇
药学   98553篇
  5篇
中国医学   2231篇
肿瘤学   77514篇
  2018年   23790篇
  2017年   19128篇
  2016年   22936篇
  2015年   14657篇
  2014年   20225篇
  2013年   29987篇
  2012年   39087篇
  2011年   48277篇
  2010年   31895篇
  2009年   29404篇
  2008年   46097篇
  2007年   50780篇
  2006年   40115篇
  2005年   40433篇
  2004年   39131篇
  2003年   39447篇
  2002年   36311篇
  2001年   66344篇
  2000年   68436篇
  1999年   56784篇
  1998年   16913篇
  1997年   15268篇
  1996年   16152篇
  1995年   16386篇
  1994年   15273篇
  1993年   14290篇
  1992年   47212篇
  1991年   45877篇
  1990年   44102篇
  1989年   41932篇
  1988年   38854篇
  1987年   38203篇
  1986年   35957篇
  1985年   34738篇
  1984年   26419篇
  1983年   22172篇
  1982年   13935篇
  1981年   12459篇
  1980年   11818篇
  1979年   23647篇
  1978年   17132篇
  1977年   14401篇
  1976年   13246篇
  1975年   13723篇
  1974年   16123篇
  1973年   15405篇
  1972年   14173篇
  1971年   13036篇
  1970年   11904篇
  1969年   11132篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
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   
43.
44.
45.
46.
47.
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   
48.
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   
49.
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   
50.
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