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   5029篇
  免费   510篇
  国内免费   10篇
耳鼻咽喉   52篇
儿科学   130篇
妇产科学   93篇
基础医学   874篇
口腔科学   167篇
临床医学   680篇
内科学   710篇
皮肤病学   89篇
神经病学   360篇
特种医学   202篇
外科学   769篇
综合类   105篇
一般理论   6篇
预防医学   571篇
眼科学   76篇
药学   365篇
中国医学   1篇
肿瘤学   299篇
  2021年   62篇
  2019年   60篇
  2018年   83篇
  2017年   54篇
  2016年   60篇
  2015年   69篇
  2014年   115篇
  2013年   162篇
  2012年   184篇
  2011年   233篇
  2010年   121篇
  2009年   116篇
  2008年   189篇
  2007年   253篇
  2006年   190篇
  2005年   185篇
  2004年   194篇
  2003年   175篇
  2002年   175篇
  2001年   194篇
  2000年   196篇
  1999年   146篇
  1998年   72篇
  1997年   59篇
  1996年   63篇
  1995年   55篇
  1994年   47篇
  1992年   98篇
  1991年   116篇
  1990年   106篇
  1989年   106篇
  1988年   100篇
  1987年   111篇
  1986年   85篇
  1985年   84篇
  1984年   87篇
  1983年   70篇
  1982年   49篇
  1981年   40篇
  1980年   46篇
  1979年   61篇
  1978年   55篇
  1977年   60篇
  1976年   45篇
  1975年   53篇
  1974年   49篇
  1973年   64篇
  1971年   49篇
  1970年   42篇
  1966年   40篇
排序方式: 共有5549条查询结果,搜索用时 15 毫秒
31.
This paper reviews the literature on colorectal cancer from a sex and gender-based perspective. Colorectal cancer is a major cause of death in the developed world, with rates increasing in developing countries. Although described by some writers as an ‘equal opportunity’ disease, it presents more risk to men than women. Both biological, or sex-linked factors, and gender-linked factors play a part in the aetiology of the disease, while gender differences in the use of screening and treatment also help shape the mortality gap between women and men for this condition. Without an appreciation of the part played by sex and gender in the risk of colorectal cancer, and without a gender-sensitive approach to screening in particular, it is possible that the mortality gap between men and women for this condition will widen in the future.  相似文献   
32.
Certified nurse-midwives and family physicians share a philosophy of family-centered maternity care. Collaboration between the two disciplines, however, has not been common. Collaboration can enhance the primary care and maternity care options available to clients of such collaborative practices. Advantages and barriers to collaboration for both types of practitioners, as well as suggestions for successful collaboration, are discussed.  相似文献   
33.
34.
Measurements of plasma atrial natriuretic peptide concentrations at 8 AM showed raised levels in 21 patients with cirrhosis and ascites (10.5 +/- 0.8 pmol/L) compared with levels in 10 age-matched controls (4.1 +/- 0.64 pmol/L; p less than 0.0001). In eight patients and 10 controls, atrial natriuretic peptide, plasma renin activity, plasma aldosterone and urinary sodium excretion were measured every 4 hr for 24 hr. Subjects were mobile between 8 AM and 11 PM and supine from 11 PM to 8 AM. In controls, urinary sodium excretion was highest between 4 PM and 11 PM (19.34 +/- 3.74 mumol/min) and lowest between midnight and 8 AM (7.06 +/- 1.23 mumol/min; p less than 0.001). In patients, urinary sodium excretion was 0.63 +/- 0.14 mumol/min between 4 PM and midnight and 1.85 +/- 0.71 mumol/min (p less than 0.08) between midnight and 8 AM. In patients during the day, mean plasma atrial natriuretic peptide concentration did not change despite large individual variation, but large, sustained rises in plasma renin activity and plasma aldosterone were seen. Correlations were noted between atrial natriuretic peptide and urinary sodium excretion between midnight and 8 AM (r = 0.65; p less than 0.02) and 4 PM and midnight (r = 0.54; p less than 0.05) but not between 8 AM and 4 PM. Plasma renin activity dropped from 12.54 +/- 2.49 at midnight to 7.41 +/- 0.88 pmol/hr/ml at 8 AM (p less than 0.05); plasma aldosterone decreased from 1,032 +/- 101 to 798 +/- 56 pmol/L (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
35.
36.
One hundred and sixty-four patients admitted to a psychogeriatric unit were given a combination of four different cognitive tests: the Mini Mental State Examination (MMSE), the Abbreviated Mental Test Score, The Felix Post Unit Score and the compilation of tests recommended by the MRC Alzheimer's Disease Workshop. The tests were compared with respect to their ability to sort accurately cases of dementia and depression, and the effects of age and education on test score and misclassification rate with diagnosis controlled for. The MMSE had a very high misclassification rate for the poorly educated and depressed group. The logistical discriminant functional analysis selected only eight items as the best discriminators between organic/ functional or dementia/depression groups. Only one of these eight was not either a memory or orientation test. The value of simply adding up tests of different aspects of cognitive function in dementia assessment or screening is questioned.  相似文献   
37.
38.
The short-term metabolic response of immature retinal ganglion cells to destruction of their target cells in the dorsal lateral geniculate nucleus (dLGN) was assessed in newborn cats. Retrograde degeneration of virtually all dLGN cells was induced by ablation of the 13 contiguous areas of visual cortex on the day of birth. The metabolic response of retinal ganglion cells to this loss of target cells in dLGN was determined by exposing the ganglion cell layer to tritiated uridine, a precursor of RNA. Control measurements were made from unoperated littermates. Following sectioning and processing of the retinae from both groups of kittens for autoradiography, silver grain densities overlying the cellular profiles in the ganglion cell layer were calculated. These calculations revealed levels of uridine incorporation at Postnatal Day 4 in both groups of kittens significantly higher than at either Postnatal Day 2 or 7, but no significant differences between the two groups on any day examined. These results show that the level of RNA synthesis in retinal ganglion cells increases temporarily during the first postnatal week and that this synthesis is unaffected by the death of target cells in the dLGN. The temporary increase may be related to the establishment of synaptic connections on retinal ganglion cells by their afferent bipolar and amacrine neurons in the inner nuclear layer.  相似文献   
39.
This study describes the use of limited proteolysis of monoclonal antibody (mAb)-bound antigens in the analysis of the two measles virus surface glycoproteins. This approach is dubbed protein "footprinting" in analogy with DNA "footprinting." Protein footprinting was superior to competitive-binding assays and as good as in vitro mAb-selected variant analysis in differentiating among mAbs with various specificities to a given protein. Proteolytic digestion of the antigen prior to mAb binding drastically reduced mAb binding resulting in poor differentiation among mAbs. In contrast, protein footprinting showed that some mAbs retained the ability to immunoprecipitate such fragments. Thus footprinting could be used for localization of mAb epitopes on a protein and proved also to be an effective means of distinguishing among mAb-selected variants differing in single epitopes. Conformational changes caused by heat-denaturation or the binding of anti-antibody to an antigen-antibody complex could also be detected by footprinting.  相似文献   
40.
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