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   862808篇
  免费   70543篇
  国内免费   1839篇
耳鼻咽喉   12827篇
儿科学   24636篇
妇产科学   25112篇
基础医学   124302篇
口腔科学   25500篇
临床医学   75385篇
内科学   164689篇
皮肤病学   16977篇
神经病学   70119篇
特种医学   35210篇
外国民族医学   171篇
外科学   136245篇
综合类   24609篇
现状与发展   2篇
一般理论   263篇
预防医学   66898篇
眼科学   20620篇
药学   64719篇
中国医学   1594篇
肿瘤学   45312篇
  2018年   7343篇
  2015年   7745篇
  2014年   11127篇
  2013年   16798篇
  2012年   22744篇
  2011年   23861篇
  2010年   13877篇
  2009年   13085篇
  2008年   22594篇
  2007年   24654篇
  2006年   24542篇
  2005年   24163篇
  2004年   23726篇
  2003年   22844篇
  2002年   21945篇
  2001年   35841篇
  2000年   36487篇
  1999年   30911篇
  1998年   9232篇
  1997年   8554篇
  1996年   8481篇
  1995年   8014篇
  1994年   7728篇
  1992年   26670篇
  1991年   26120篇
  1990年   25637篇
  1989年   24700篇
  1988年   23230篇
  1987年   22904篇
  1986年   21753篇
  1985年   21108篇
  1984年   16391篇
  1983年   14003篇
  1982年   8854篇
  1981年   8206篇
  1980年   7672篇
  1979年   16744篇
  1978年   12119篇
  1977年   10188篇
  1976年   9332篇
  1975年   10149篇
  1974年   12646篇
  1973年   12140篇
  1972年   11543篇
  1971年   10687篇
  1970年   10223篇
  1969年   9912篇
  1968年   8903篇
  1967年   8232篇
  1966年   7654篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
1.
2.
3.
4.
5.
6.
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   
7.
8.
9.
10.
The value of adding simeprevir (SMV) vs placebo (PBO) to peginterferon and ribavirin (PR) for treatment of chronic hepatitis C virus infection was examined using patient‐reported outcomes (PROs); further, concordance of PROs with virology endpoints and adverse events (AEs) was explored. Patients (= 768 SMV/PR,= 393 PBO/PR) rated fatigue (FSS), depressive symptoms (CES‐D) and functional impairment (WPAI: Hepatitis C Productivity, Daily Activity and Absenteeism) at baseline and throughout treatment in three randomised, double‐blind trials comparing the addition of SMV or PBO during initial 12 weeks of PR. PR was administered for 48 weeks (PBO group) and 24/48 weeks (SMV group) using a response‐guided therapy (RGT) approach. Mean PRO scores (except Absenteeism) worsened from baseline to Week 4 to the same extent in both groups but reverted after Week 24 for SMV/PR and only after Week 48 for PBO/PR. Accordingly, there was a significantly lower area under the curve (baseline–Week 60, AUC60) and fewer weeks with clinically important worsening of scores in the SMV/PR group at any time point. Incidences of patients with fatigue and anaemia AEs were similar in both groups, but FSS scores showed that clinically important increases in fatigue lasted a mean of 6.9 weeks longer with PBO/PR (P < 0.001). PRO score subgroup analysis indicated better outcomes for patients who met the criteria for RGT or achieved sustained virological response 12 weeks post‐treatment (SVR12); differences in mean PRO scores associated with fibrosis level were only observed with PBO/PR. Greater efficacy of SMV/PR enabled reduced treatment duration and reduced time with PR‐related AEs without adding to AE severity.  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