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   476912篇
  免费   20716篇
  国内免费   839篇
耳鼻咽喉   6877篇
儿科学   17092篇
妇产科学   15696篇
基础医学   68205篇
口腔科学   12866篇
临床医学   38229篇
内科学   87978篇
皮肤病学   10529篇
神经病学   31852篇
特种医学   21644篇
外国民族医学   139篇
外科学   73465篇
综合类   8768篇
现状与发展   1篇
一般理论   161篇
预防医学   35332篇
眼科学   10974篇
药学   33537篇
  2篇
中国医学   913篇
肿瘤学   24207篇
  2018年   6983篇
  2017年   6393篇
  2016年   6125篇
  2015年   8136篇
  2014年   8646篇
  2013年   10394篇
  2012年   18404篇
  2011年   13824篇
  2010年   8146篇
  2009年   9168篇
  2008年   10501篇
  2007年   12063篇
  2006年   12163篇
  2005年   19727篇
  2004年   20883篇
  2003年   16101篇
  2002年   10978篇
  2001年   17200篇
  2000年   15171篇
  1999年   16634篇
  1998年   3497篇
  1997年   3020篇
  1996年   2948篇
  1995年   2882篇
  1992年   14454篇
  1991年   14790篇
  1990年   14806篇
  1989年   14330篇
  1988年   13107篇
  1987年   12691篇
  1986年   12140篇
  1985年   11245篇
  1984年   8023篇
  1983年   6765篇
  1982年   3381篇
  1980年   2770篇
  1979年   7924篇
  1978年   5409篇
  1977年   4384篇
  1976年   3925篇
  1975年   5134篇
  1974年   6210篇
  1973年   5922篇
  1972年   5690篇
  1971年   5509篇
  1970年   5238篇
  1969年   4904篇
  1968年   4645篇
  1967年   4412篇
  1966年   4052篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Two Janus-associated kinase inhibitors (JAKi) (initially ruxolitinib and, more recently, fedratinib) have been approved as treatment options for patients who have intermediate-risk and high-risk myelofibrosis (MF), with pivotal trials demonstrating improvements in spleen volume, disease symptoms, and quality of life. At the same time, however, clinical trial experiences with JAKi agents in MF have demonstrated a high frequency of discontinuations because of adverse events or progressive disease. In addition, overall survival benefits and clinical and molecular predictors of response have not been established in this population, for which the disease burden is high and treatment options are limited. Consistently poor outcomes have been documented after JAKi discontinuation, with survival durations after ruxolitinib ranging from 11 to 16 months across several studies. To address such a high unmet therapeutic need, various non-JAKi agents are being actively explored (in combination with ruxolitinib in first-line or salvage settings and/or as monotherapy in JAKi-pretreated patients) in phase 3 clinical trials, including pelabresib (a bromodomain and extraterminal domain inhibitor), navitoclax (a B-cell lymphoma 2/B-cell lymphoma 2-xL inhibitor), parsaclisib (a phosphoinositide 3-kinase inhibitor), navtemadlin (formerly KRT-232; a murine double-minute chromosome 2 inhibitor), and imetelstat (a telomerase inhibitor). The breadth of data expected from these trials will provide insight into the ability of non-JAKi treatments to modify the natural history of MF.  相似文献   
3.
4.
5.
6.
7.
8.
9.
10.
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   
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