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   19342篇
  免费   1977篇
  国内免费   34篇
耳鼻咽喉   267篇
儿科学   718篇
妇产科学   537篇
基础医学   2765篇
口腔科学   602篇
临床医学   2374篇
内科学   3552篇
皮肤病学   334篇
神经病学   1689篇
特种医学   772篇
外科学   2301篇
综合类   501篇
一般理论   9篇
预防医学   2090篇
眼科学   283篇
药学   1516篇
中国医学   23篇
肿瘤学   1020篇
  2021年   292篇
  2020年   179篇
  2019年   289篇
  2018年   350篇
  2017年   282篇
  2016年   294篇
  2015年   317篇
  2014年   444篇
  2013年   649篇
  2012年   794篇
  2011年   825篇
  2010年   539篇
  2009年   458篇
  2008年   838篇
  2007年   831篇
  2006年   860篇
  2005年   731篇
  2004年   716篇
  2003年   653篇
  2002年   665篇
  2001年   631篇
  2000年   654篇
  1999年   535篇
  1998年   262篇
  1997年   207篇
  1996年   228篇
  1995年   219篇
  1994年   197篇
  1993年   220篇
  1992年   457篇
  1991年   428篇
  1990年   424篇
  1989年   447篇
  1988年   435篇
  1987年   344篇
  1986年   361篇
  1985年   393篇
  1984年   273篇
  1983年   220篇
  1982年   165篇
  1981年   165篇
  1979年   212篇
  1978年   189篇
  1977年   203篇
  1976年   173篇
  1975年   166篇
  1974年   172篇
  1973年   181篇
  1972年   169篇
  1971年   163篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
On the day before birth, rat fetuses respond to an intraoral infusion of milk with a stretch response that resembles the behavior of suckling pups at the nipple. Unlike the postnatal response, which occurs coincident with milk ejection, the fetal stretch occurs 3-5 min after milk infusion. Measurement of fetal heart rate (HR) is useful as a predictor of the fetal stretch response. Expression of the stretch response was preceded by a reduction in HR variability and a transient episode of bradycardia. Fetuses that did not stretch showed a delayed reduction in HR variability and no evidence of HR deceleration. Systematic changes in fetal HR may be indicative of changes in fetal state associated with milk infusion and the stretch response.  相似文献   
42.
Recent studies of mortality from motor neurone disease (MND) in Sweden have demonstrated rising levels of mortality from the disease, especially amongst older age groups. Case-control investigations have suggested that certain environmental factors are significantly related to variations in mortality from the disease, and are associated with a probable individual susceptibility to MND. This study applies an innovative epidemiological technique to longitudinal and cohort analysis of Swedish mortality from MND during the period 1961 to 1990. Survival modelling shows that a subpopulation susceptible to MND exists in Sweden, as has been demonstrated in other countries. The increased life expectancy of the Swedish population since 1961 has resulted in more of that susceptible population living to the ages at which MND is expressed, explaining the majority of the increase in mortality from the disease. However, environmental factors may play a role in accelerating the course of MND and may affect the timing of death within the susceptible sub-population.  相似文献   
43.
44.
45.
46.
Differential mood changes following basal ganglia vs thalamic lesions   总被引:3,自引:0,他引:3  
Patients with computed tomographic scan-verified unilateral lesions in the basal ganglia or thalamus were examined for the presence of poststroke mood disorders. Patients with left-sided basal ganglia lesions (mainly in the head of the caudate nucleus) showed a significantly higher frequency and severity of depression, as compared with patients with right-sided basal ganglia or thalamic (left- or right-sided) lesions. Results suggest that damage to biogenic amine pathways and/or frontocaudate projections may play an important role in the modulation of mood.  相似文献   
47.
Abnormalities of copper in Gilles de la Tourette syndrome   总被引:1,自引:0,他引:1  
The Gilles de la Tourette syndrome is a disorder whose etiology and pathogenesis are little understood. The number of biochemical abnormalities described in this disorder is minimal. Ten of a total of 80 patients were found to have an abnormally low serum copper. A report is presented on two patients who consented to further detailed investigation and in whom copper radioisotope studies were carried out. Both exhibited abnormalities of copper handling, in that we observed an abnormally fast disappearance of copper from the plasma and an abnormally slow uptake by the liver. The rates of intestinal absorption and urinary excretion were normal. We did not identify an abnormal site of sequestration of the metal in the body.  相似文献   
48.
Over the past 20 years there has not only been a substantialincrease in indicators of alcoholrelated harm, but also an increasein professional and public awareness of alcohol problems andthe need to prevent them. Sadly, however, much of this awarenessof the need for prevention has resulted in little more thanrather desultory calls for more education. From my ‘pointof view’ it is time to shift further some of the emphasesin the debate aboust alcohol, education and action.  相似文献   
49.
The spatial distribution of twitch and tonic fibres in a snake muscle one myofibre thick (ventral costocutaneous) has been investigated. It was found that small groups of like fibres were favoured at the expense of larger groups when compared with sequences generated by a computer in which fibres were distributed randomly. The number of times that like fibres occurred next to one another was used as another measure of their spatial distribution. The number of adjacencies of like fibres was less than the expected number of adjacencies determined both by random sequences and by probability theory. The expected number of adjacencies determined by means of random sequences and a priori probability theory were almost identical. This dispersion of like fibres may reflect processes that occur during muscle development and may have functional implications.  相似文献   
50.
Despite the widespread conservative management of breast cancer, the pathologists' examination of these specimens is far from uniform. Pathologists sample margins differently, and even disagree on what constitutes a positive margin. This variability in the pathologic examination of the lumpectomy creates tremendous problems in analyzing the existing literature on the importance of positive margins. Herein is a discussion of the available data on the significance of margin assessment. We furthermore suggest a practical approach to examining margins with an emphasis on a functional orientation of the specimen with respect to the nipple. Only by adopting a uniform system of margin assessment can we begin to critically evaluate the importance of positive margins in segmental resections of the breast.  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