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   863126篇
  免费   70558篇
  国内免费   1841篇
耳鼻咽喉   12808篇
儿科学   24650篇
妇产科学   25123篇
基础医学   124345篇
口腔科学   25505篇
临床医学   75408篇
内科学   164764篇
皮肤病学   16987篇
神经病学   70109篇
特种医学   35221篇
外国民族医学   171篇
外科学   136312篇
综合类   24618篇
现状与发展   2篇
一般理论   264篇
预防医学   66899篇
眼科学   20553篇
药学   64746篇
中国医学   1597篇
肿瘤学   45443篇
  2018年   7369篇
  2015年   7748篇
  2014年   11138篇
  2013年   16833篇
  2012年   22783篇
  2011年   23883篇
  2010年   13901篇
  2009年   13086篇
  2008年   22620篇
  2007年   24681篇
  2006年   24541篇
  2005年   24180篇
  2004年   23750篇
  2003年   22868篇
  2002年   21961篇
  2001年   35850篇
  2000年   36496篇
  1999年   30922篇
  1998年   9238篇
  1997年   8555篇
  1996年   8483篇
  1995年   8018篇
  1994年   7729篇
  1992年   26676篇
  1991年   26122篇
  1990年   25631篇
  1989年   24683篇
  1988年   23228篇
  1987年   22893篇
  1986年   21748篇
  1985年   21109篇
  1984年   16395篇
  1983年   13999篇
  1982年   8861篇
  1981年   8207篇
  1980年   7676篇
  1979年   16737篇
  1978年   12120篇
  1977年   10185篇
  1976年   9328篇
  1975年   10148篇
  1974年   12641篇
  1973年   12136篇
  1972年   11542篇
  1971年   10686篇
  1970年   10221篇
  1969年   9910篇
  1968年   8900篇
  1967年   8232篇
  1966年   7653篇
排序方式: 共有10000条查询结果,搜索用时 12 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