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   16330篇
  免费   2169篇
  国内免费   24篇
耳鼻咽喉   114篇
儿科学   703篇
妇产科学   326篇
基础医学   2444篇
口腔科学   466篇
临床医学   1753篇
内科学   3667篇
皮肤病学   153篇
神经病学   1184篇
特种医学   627篇
外科学   2547篇
综合类   438篇
一般理论   15篇
预防医学   1675篇
眼科学   191篇
药学   1414篇
中国医学   5篇
肿瘤学   801篇
  2021年   206篇
  2020年   150篇
  2019年   203篇
  2018年   239篇
  2017年   187篇
  2016年   162篇
  2015年   206篇
  2014年   332篇
  2013年   453篇
  2012年   671篇
  2011年   682篇
  2010年   370篇
  2009年   350篇
  2008年   664篇
  2007年   738篇
  2006年   682篇
  2005年   695篇
  2004年   678篇
  2003年   684篇
  2002年   682篇
  2001年   607篇
  2000年   637篇
  1999年   556篇
  1998年   247篇
  1997年   202篇
  1996年   220篇
  1995年   191篇
  1994年   210篇
  1993年   190篇
  1992年   451篇
  1991年   420篇
  1990年   421篇
  1989年   359篇
  1988年   344篇
  1987年   314篇
  1986年   315篇
  1985年   340篇
  1984年   264篇
  1983年   204篇
  1982年   163篇
  1981年   169篇
  1979年   235篇
  1978年   173篇
  1977年   186篇
  1976年   144篇
  1975年   162篇
  1974年   202篇
  1973年   203篇
  1972年   134篇
  1971年   132篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
A cohort of 1163 pregnant women in two small towns in South Wales, UK, was identified and followed until the children born to them were five years of age. Growth in these children is described and a number of determinants identified. Social-class differences were very small at birth but differences in height became clear by the age of two years and in head circumference before this. In height the differences were largely accounted for by greater growth in social class I, but there was a gradient in head circumference throughout all the social classes. The social class effects gradually increased as the children became older. Parity of the mothers had a small effect on size at birth but age of the mother had no effect once parity was allowed for. Data on illnesses in the children were collected but no effect on growth could be detected. By far the most important determinant of growth which could be controlled is maternal smoking. About 40% of the women smoked, about 17% heavily (15 or more cigarettes per day) and the prevalence of smoking altered little during pregnancy. There was a graded effect of smoking on growth up to a 9% deficit in birth-weight, a 2% deficit in length at birth and a 1.5% deficit in head circumference in the babies born to the mothers who smoked most heavily (25 or more cigarettes per day) compared with non-smokers. There effects decreased with age but there were still residual effects at age five years.  相似文献   
2.
3.
4.
We thank Coceani and L'Abbate for their comments on our paper.We concur that ‘pathophysiology cannot be inferred fromcoronary lumenography alone’, and this was one of thekey motivations in conducting the present study.  相似文献   
5.
The second documented case of renal aspergilloma due to Aspergillusflavus is presented. The merits of the medical therapy thatfailed are discussed. Pathological examination showed a nidusof aspergillus around suture material persisting from a pyelolithotomyoperation 2 years before in India. We argue that this was thereason for the failure of the medical therapy. This is the firstcase of its kind reported.  相似文献   
6.
BACKGROUND: The demand for renal replacement therapy (RRT) in England has risen steadily, although from a lower base than many other developed countries. Predicting the future demand for RRT and the impact of factors such as the acceptance rate, transplant supply and patient survival, is required in order to inform the planning of such services. METHODS: A discrete event simulation model estimates the future demand for RRT in England in 2010 for a range of scenarios. The model uses current prevalence and current and projected future acceptance rates, survival rates and the transitions between modalities to predict future patient numbers. National population and mortality data, published literature and data from the UK Renal Registry and UK Transplant, are used to estimate unmet need for RRT, the impact of changing demography and incidence of Type 2 diabetes, patient haemodialysis (HD) survival and transplant supply. RESULTS: By 2010 the predicted prevalence will have increased from about 30,000 in 2000 to between 42 and 51,000 (900-1000 p.m.p.), an average annual growth of 4.5-6%. Changing transplant supply has a small effect on overall numbers but changes the proportion of patients with functioning graft by up to 8%. Even with an optimistic increase in transplant supply (11% p.a. for 5 years), numbers on HD will continue to rise substantially, especially in the elderly. The factors most influencing future patient numbers are the acceptance rate and dialysis survival. CONCLUSION: This model predicts a substantial growth in the RRT population to 2010 to a rate approaching 1000 p.m.p., particularly in the elderly and those on HD, with a steady state not being reached for at least 25 years.  相似文献   
7.
    
We present our comments on the above article.  相似文献   
8.
9.
10.
We have described a method for the microtransplantation of a suspension of a few thousand cells from mid to late embryonic mouse hippocampi into the fimbria of immunosuppressed adult rat hosts. There was close graft-to-host contact, across a non-scarred interface. The transplanted cells included CA3 type pyramids, and were enclosed within the host myelinated fibre tract, whose glial framework was largely undisturbed. Immunohistochemistry of two species-specific markers (M6 and Thy-1.2) showed that the donor mouse neurons grew fine (<0.5 μm diameter) axons which extended singly or in fascicles through the rat host fimbria for a maximum distance of at least 10 mm. The donor axons were intimately integrated among and closely aligned to the host tract axons and to the interfascicular glial rows of the host tract. The axons travelled (i) laterally through the ipsilateral fimbria, (ii) medially across the midline in the ventral hippocampal commissure to reach the contralateral fimbria and alveus, and (iii) rostro-medially to the septum. On approaching the terminal fields appropriate to hippocampal CA3 pyramidal cell axons, the transplant axons gave rise to fine preterminal branches which were continuous with a reticular or amorphous immunoreactivity in the stratum oriens and stratum pyramidale of the ipsilateral hippocampus, and in the lateral and triangular septal nuclei. The donor axons extended along the host fimbria at a rate of ∼ 1 mm per day, reaching their terminal field destinations by ∼1–2 weeks. At 7 weeks the projections were maintained, but with little further extension. These observations indicate that the microenvironment of myelinated adult fibre tracts is permissive for an abundant and rapid growth of axons from transplanted embryonic cell suspensions. These axons can leave host tracts to invade appropriate terminal fields.  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