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   307410篇
  免费   17690篇
  国内免费   423篇
耳鼻咽喉   4619篇
儿科学   11309篇
妇产科学   10675篇
基础医学   45592篇
口腔科学   8300篇
临床医学   24951篇
内科学   57666篇
皮肤病学   6615篇
神经病学   21743篇
特种医学   12133篇
外国民族医学   43篇
外科学   49204篇
综合类   7835篇
现状与发展   1篇
一般理论   166篇
预防医学   20198篇
眼科学   7309篇
药学   21462篇
中国医学   822篇
肿瘤学   14880篇
  2021年   2412篇
  2019年   2444篇
  2018年   3992篇
  2017年   2992篇
  2016年   3489篇
  2015年   3778篇
  2014年   5015篇
  2013年   7847篇
  2012年   9744篇
  2011年   10234篇
  2010年   6550篇
  2009年   5798篇
  2008年   9372篇
  2007年   10246篇
  2006年   10112篇
  2005年   9680篇
  2004年   9398篇
  2003年   8831篇
  2002年   8437篇
  2001年   13643篇
  2000年   14023篇
  1999年   11645篇
  1998年   3094篇
  1997年   2852篇
  1996年   2695篇
  1995年   2571篇
  1992年   8317篇
  1991年   8455篇
  1990年   8264篇
  1989年   8082篇
  1988年   7315篇
  1987年   7076篇
  1986年   6720篇
  1985年   6514篇
  1984年   4762篇
  1983年   4120篇
  1982年   2469篇
  1979年   4429篇
  1978年   3230篇
  1977年   2733篇
  1976年   2503篇
  1975年   2834篇
  1974年   3355篇
  1973年   3362篇
  1972年   3123篇
  1971年   2949篇
  1970年   2838篇
  1969年   2581篇
  1968年   2539篇
  1967年   2374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