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   693篇
  免费   34篇
  国内免费   61篇
耳鼻咽喉   10篇
儿科学   41篇
妇产科学   26篇
基础医学   76篇
口腔科学   19篇
临床医学   93篇
内科学   149篇
皮肤病学   11篇
神经病学   25篇
特种医学   88篇
外科学   70篇
综合类   56篇
一般理论   2篇
预防医学   33篇
眼科学   12篇
药学   55篇
中国医学   1篇
肿瘤学   21篇
  2021年   8篇
  2017年   5篇
  2016年   5篇
  2015年   11篇
  2014年   8篇
  2013年   12篇
  2012年   9篇
  2011年   7篇
  2010年   18篇
  2009年   25篇
  2008年   4篇
  2007年   45篇
  2006年   14篇
  2005年   14篇
  2004年   4篇
  2002年   8篇
  2001年   6篇
  2000年   10篇
  1999年   17篇
  1998年   34篇
  1997年   44篇
  1996年   32篇
  1995年   26篇
  1994年   15篇
  1993年   27篇
  1992年   6篇
  1991年   11篇
  1990年   9篇
  1989年   23篇
  1988年   12篇
  1987年   11篇
  1986年   7篇
  1985年   9篇
  1984年   10篇
  1983年   8篇
  1982年   7篇
  1981年   9篇
  1980年   17篇
  1978年   4篇
  1976年   4篇
  1975年   4篇
  1959年   14篇
  1958年   44篇
  1957年   23篇
  1956年   21篇
  1955年   33篇
  1954年   26篇
  1949年   6篇
  1948年   15篇
  1947年   6篇
排序方式: 共有788条查询结果,搜索用时 15 毫秒
1.
The initial management of bladder outflow obstruction typically related to benign prostatic hyperplasia (BPH) falls to a large extent within the remit of general practice. Referral onwards to secondary care typically arises following the failure to respond to conservative measures or when complications have supervened; the most significant of which is urinary retention. In the hospital setting, anaesthesia, constipation and immobility are the common precipitants. What follows is a practical guide to the management of these situations and provides an overview of the conservative, medical, minimally invasive and surgical treatments available.  相似文献   
2.
3.
4.
Abstract Thyroid hormones were measured before, during and after acute exercise (60 min) or physical training (3 months) in obese women. Thyroid stimulating hormone concentration increased during acute work and decreased immediately after. No changes were seen during the two following days. An increase was seen after ten days as well as after three months of physical training. Thyroxine concentrations showed no changes. 3,5,3′-Triiodothyronine decreased slightly immediately after acute exercise, and after three months of physical training, 3,3′,5′-triiodothyronine (reverse triiodothyronine) increased slowly during and after acute exercise. A negative correlation was found between changes in fasting insulin and thyroxine and a positive correlation between changes in blood pressure and triiodothyronine after training. Lack of agreement in previous reports is probably due to methodological differences such as methods more or less susceptible to fatty acid interference, and thyroid hormones changing differently during acute work and before and after physical training. The duration of the study may also be of importance, even 3 months possibly being too short for attaining equilibrium in thyroid homeostasis.  相似文献   
5.

Background  

There is currently an unprecedented expressed need and demand for estimates of maternal mortality in developing countries. This has been stimulated in part by the creation of a Millennium Development Goal that will be judged partly on the basis of reductions in maternal mortality by 2015.  相似文献   
6.
7.
8.
Pneumocystis carinii is a major opportunistic pathogen and leading cause of morbidity in patients with AIDS. The major surface glycoprotein (MSG) of P. carinii, represented by a family of related proteins encoded by unique genes, is highly immunogenic and contains T cell-protective epitopes. We undertook the present study to define the CD4 T helper (Th) response by cytokine secretion to native MSG and a recombinant form of the protein, MSG-B. Spleen cells were collected from Lewis rats and restimulated with both native MSG and MSG-B. Within 24 h, the CD4 cells secreted high levels of interferon-gamma (IFN-γ) in response to both types of antigen, indicative of a Th1 response; however, after 72 h of incubation, only the native MSG stimulated secretion of IL-4 (Th2 response) from the cells. We then investigated whether the presence of IL-4 could alter the predominant Th1 phenotype by the CD4 cells in response to MSG and MSG-B. Cells cultured with native MSG and IL-4 produced low levels of IFN-γ and elevated levels of IL-4. Interestingly, cells incubated with MSG-B and IL-4 reduced production of IFN-γ, but were not stimulated to produce increased levels of IL-4. The presence of anti-IFN-γ antibody in the MSG- or MSG-B-stimulated cultures did not effect the expression of IFN-γ mRNA, suggesting that the generation of Th1 cells in response to MSG or MSG-B was not dependent on IFN-γ. We conclude that native MSG, which contains multiple forms of this antigen, and recombinant MSG elicit different cytokine responses in vitro. These data are not only important to studies of MSG, but may also be relevant to the role of MSG in the immunopathogenesis of P.carinii infection in vivo.  相似文献   
9.
Susceptibility to autoimmune insulin-dependent (type 1) diabetes mellitus is determined by a combination of environmental and genetic factors, which include variation in MHC genes on chromosome 6p21 (IDDM1) and the insulin gene on chromosome 11p15 (IDDM2). However, linkage to IDDM1 and IDDM2 cannot explain the clustering of type 1 diabetes in families, and a role for other genes is inferred. In the present report we describe linkage and association of type 1 diabetes to the CTLA-4 gene (cytotoxic T lymphocyte associated-4) on chromosome 2q33 (designated IDDM12). CTLA-4 is a strong candidate gene for T cell- mediated autoimmune disease because it encodes a T cell receptor that mediates T cell apoptosis and is a vital negative regulator of T cell activation. In addition, we provide supporting evidence that CTLA-4 is associated with susceptibility to Graves' disease, another organ- specific autoimmune disease.   相似文献   
10.
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