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   307910篇
  免费   18170篇
  国内免费   418篇
耳鼻咽喉   4535篇
儿科学   10830篇
妇产科学   10616篇
基础医学   46398篇
口腔科学   7882篇
临床医学   25264篇
内科学   58042篇
皮肤病学   6499篇
神经病学   22267篇
特种医学   12133篇
外国民族医学   43篇
外科学   47980篇
综合类   7970篇
现状与发展   1篇
一般理论   183篇
预防医学   20886篇
眼科学   7310篇
药学   21419篇
中国医学   796篇
肿瘤学   15444篇
  2019年   2369篇
  2018年   3795篇
  2017年   2771篇
  2016年   3219篇
  2015年   3621篇
  2014年   4790篇
  2013年   7522篇
  2012年   9509篇
  2011年   9917篇
  2010年   6362篇
  2009年   5802篇
  2008年   9065篇
  2007年   9975篇
  2006年   9825篇
  2005年   9360篇
  2004年   9070篇
  2003年   8539篇
  2002年   8173篇
  2001年   13711篇
  2000年   14041篇
  1999年   11739篇
  1998年   3149篇
  1997年   2892篇
  1996年   2750篇
  1995年   2657篇
  1994年   2458篇
  1992年   8666篇
  1991年   8814篇
  1990年   8608篇
  1989年   8378篇
  1988年   7623篇
  1987年   7401篇
  1986年   7018篇
  1985年   6795篇
  1984年   4941篇
  1983年   4297篇
  1982年   2577篇
  1979年   4620篇
  1978年   3400篇
  1977年   2851篇
  1976年   2600篇
  1975年   2947篇
  1974年   3478篇
  1973年   3484篇
  1972年   3228篇
  1971年   3044篇
  1970年   2912篇
  1969年   2670篇
  1968年   2617篇
  1967年   2450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.
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   
9.
10.
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