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   3021篇
  免费   286篇
  国内免费   5篇
耳鼻咽喉   24篇
儿科学   69篇
妇产科学   52篇
基础医学   378篇
口腔科学   33篇
临床医学   385篇
内科学   547篇
皮肤病学   39篇
神经病学   227篇
特种医学   107篇
外科学   329篇
综合类   47篇
一般理论   4篇
预防医学   415篇
眼科学   131篇
药学   255篇
中国医学   2篇
肿瘤学   268篇
  2023年   21篇
  2022年   40篇
  2021年   66篇
  2020年   38篇
  2019年   60篇
  2018年   80篇
  2017年   43篇
  2016年   47篇
  2015年   68篇
  2014年   72篇
  2013年   106篇
  2012年   144篇
  2011年   189篇
  2010年   73篇
  2009年   91篇
  2008年   138篇
  2007年   132篇
  2006年   159篇
  2005年   145篇
  2004年   143篇
  2003年   131篇
  2002年   121篇
  2001年   69篇
  2000年   81篇
  1999年   59篇
  1998年   26篇
  1997年   20篇
  1996年   21篇
  1995年   20篇
  1994年   18篇
  1993年   17篇
  1992年   69篇
  1991年   69篇
  1990年   57篇
  1989年   70篇
  1988年   54篇
  1987年   61篇
  1986年   44篇
  1985年   41篇
  1984年   36篇
  1983年   37篇
  1982年   20篇
  1981年   21篇
  1980年   15篇
  1979年   30篇
  1978年   26篇
  1977年   16篇
  1974年   17篇
  1973年   22篇
  1972年   15篇
排序方式: 共有3312条查询结果,搜索用时 15 毫秒
61.
Abstract

The influence of event characteristics on recall was examined by directly comparing fall-off in reporting life events as a function of life change, desirability, and anticipation. We collected information from a sample of 1,669 blue-collar workers on stressful life events that occurred in a 1-year interval before the questionnaire was administered. The results indicated no fall-off in reporting events associated with marked life changes (ie, salient events). In contrast, significant fall-off was observed for events characterized by varying degrees of desirability and anticipation. Although ratings of desirability and saliency were not independent, saliency of life events emerged as the dimension most closely associated with accuracy of event reporting. Research on the reliability of measures of life events and the association between event characteristics and illness should consider the kinds of systematic reporting differences observed here.  相似文献   
62.
63.

OBJECTIVE

Gut microbiome dysbiosis is associated with numerous diseases, including type 1 diabetes. This pilot study determines how geographical location affects the microbiome of infants at high risk for type 1 diabetes in a population of homogenous HLA class II genotypes.

RESEARCH DESIGN AND METHODS

High-throughput 16S rRNA sequencing was performed on stool samples collected from 90 high-risk, nonautoimmune infants participating in The Environmental Determinants of Diabetes in the Young (TEDDY) study in the U.S., Germany, Sweden, and Finland.

RESULTS

Study site–specific patterns of gut colonization share characteristics across continents. Finland and Colorado have a significantly lower bacterial diversity, while Sweden and Washington state are dominated by Bifidobacterium in early life. Bacterial community diversity over time is significantly different by geographical location.

CONCLUSIONS

The microbiome of high-risk infants is associated with geographical location. Future studies aiming to identify the microbiome disease phenotype need to carefully consider the geographical origin of subjects.  相似文献   
64.
65.
66.
We use stable isotope ratios in feces of wild mountain gorillas (Gorilla beringei) to test the hypothesis that diet shifts within a single year, as measured by dry mass intake, can be recovered. Isotopic separation of staple foods indicates that intraannual changes in the isotopic composition of feces reflect shifts in diet. Fruits are isotopically distinct compared with other staple foods, and peaks in fecal δ13C values are interpreted as periods of increased fruit feeding. Bayesian mixing model results demonstrate that, although the timing of these diet shifts match observational data, the modeled increase in proportional fruit feeding does not capture the full shift. Variation in the isotopic and nutritional composition of gorilla foods is largely independent, highlighting the difficulty for estimating nutritional intake with stable isotopes. Our results demonstrate the potential value of fecal sampling for quantifying short-term, intraindividual dietary variability in primates and other animals with high temporal resolution even when the diet is composed of C3 plants.  相似文献   
67.
68.
69.
70.
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