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   862515篇
  免费   70508篇
  国内免费   1839篇
耳鼻咽喉   12801篇
儿科学   24652篇
妇产科学   25106篇
基础医学   124269篇
口腔科学   25488篇
临床医学   75346篇
内科学   164600篇
皮肤病学   16977篇
神经病学   70111篇
特种医学   35214篇
外国民族医学   171篇
外科学   136166篇
综合类   24617篇
现状与发展   2篇
一般理论   263篇
预防医学   66929篇
眼科学   20519篇
药学   64735篇
中国医学   1594篇
肿瘤学   45302篇
  2018年   7337篇
  2015年   7729篇
  2014年   11109篇
  2013年   16794篇
  2012年   22729篇
  2011年   23835篇
  2010年   13869篇
  2009年   13066篇
  2008年   22583篇
  2007年   24623篇
  2006年   24507篇
  2005年   24145篇
  2004年   23706篇
  2003年   22840篇
  2002年   21934篇
  2001年   35831篇
  2000年   36482篇
  1999年   30914篇
  1998年   9223篇
  1997年   8547篇
  1996年   8477篇
  1995年   8016篇
  1994年   7729篇
  1992年   26671篇
  1991年   26111篇
  1990年   25635篇
  1989年   24688篇
  1988年   23237篇
  1987年   22900篇
  1986年   21748篇
  1985年   21108篇
  1984年   16390篇
  1983年   14001篇
  1982年   8857篇
  1981年   8205篇
  1980年   7674篇
  1979年   16741篇
  1978年   12117篇
  1977年   10182篇
  1976年   9329篇
  1975年   10149篇
  1974年   12644篇
  1973年   12136篇
  1972年   11542篇
  1971年   10689篇
  1970年   10218篇
  1969年   9912篇
  1968年   8905篇
  1967年   8235篇
  1966年   7656篇
排序方式: 共有10000条查询结果,搜索用时 15 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