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   25524篇
  免费   1623篇
  国内免费   162篇
耳鼻咽喉   316篇
儿科学   787篇
妇产科学   730篇
基础医学   2598篇
口腔科学   733篇
临床医学   2135篇
内科学   5726篇
皮肤病学   530篇
神经病学   1146篇
特种医学   882篇
外国民族医学   9篇
外科学   4520篇
综合类   735篇
现状与发展   1篇
一般理论   23篇
预防医学   1747篇
眼科学   729篇
药学   2249篇
中国医学   166篇
肿瘤学   1547篇
  2023年   360篇
  2022年   1057篇
  2021年   1475篇
  2020年   768篇
  2019年   987篇
  2018年   1314篇
  2017年   792篇
  2016年   819篇
  2015年   909篇
  2014年   1132篇
  2013年   1371篇
  2012年   1931篇
  2011年   1988篇
  2010年   1044篇
  2009年   865篇
  2008年   1234篇
  2007年   1330篇
  2006年   1171篇
  2005年   1022篇
  2004年   966篇
  2003年   803篇
  2002年   728篇
  2001年   344篇
  2000年   335篇
  1999年   308篇
  1998年   165篇
  1997年   121篇
  1996年   108篇
  1995年   111篇
  1994年   73篇
  1993年   59篇
  1992年   133篇
  1991年   124篇
  1990年   117篇
  1989年   103篇
  1988年   98篇
  1987年   95篇
  1986年   97篇
  1985年   86篇
  1984年   68篇
  1983年   89篇
  1982年   36篇
  1981年   46篇
  1980年   32篇
  1979年   80篇
  1978年   44篇
  1977年   52篇
  1976年   41篇
  1975年   44篇
  1974年   38篇
排序方式: 共有10000条查询结果,搜索用时 47 毫秒
91.
92.
Background : Bladder augmentation may be undertaken by using various gastrointestinal segments but their use is associated with a multitude of well-recognized complications. The mega-ureter has proven to be a satisfactory alternative; in patients with bilateral mega-ureters, both ureters may be used for this purpose. Methods : Seventeen patients had augmentation ureterocystoplasty, including three in whom both distal ureters were used in tandem. The latter included two patients with neurogenic bladder and one with bladder exstrophy. Results : Satisfactory augmentation was achieved in all patients undergoing tandem ureterocystoplasty. The neurogenic bladder patients are managed by urethral clean intermittent catheterization (CIC) and the exstrophy patient is managed by CIC of an appendico-vesicostomy (Mitrofanoff). All are continent. Conclusions : The mega-ureter provides an excellent source of augmentation material in patients with small non-compliant bladders. In those with bilateral mega-ureters, consideration should be given to using both ureters in tandem to achieve the maximum possible bladder capacity.  相似文献   
93.
94.
95.
Members of the epidermal growth factor (EGF) family and their receptors are involved in many cellular processes, including proliferation, migration, and differentiation. We have previously reported that these growth factors are expressed and have specific regulatory functions in an organ-like culture model of normal human urothelial cells. Here, we used this model to investigate the involvement of EGF receptor (EGFR) in human urothelial regeneration. Three 4-mm-diameter damaged areas were made in confluent normal human urothelial cell cultures with a biopsy punch. Regeneration was measured, on fixed stained cultures, with an image analyzer, at 4, 24, and 48 hours after injury. Cell proliferation was assessed by 5-bromo-2-deoxyuridine incorporation. To identify EGF family factors potentially involved in the healing process, we studied the effect of these factors on damaged confluent cultures and the level of expression of mRNAs extracted from these cultures. EGFR inhibition of the proliferation and migration of urothelial cells was tested with (1). a specific tyrosine kinase inhibitor (AG1478) and (2). a blocking anti-EGFR antibody (LA22). Exogenously added amphiregulin, EGF, transforming growth factor-alpha and heparin-binding EGF (HB-EGF) stimulated urothelial regeneration. The damaged areas were repaired by regrowth within 48 hours. Both AG1478 and LA22 inhibited the repair (by 50% and 30%, respectively), as well as proliferation and migration. This regeneration was accompanied by increased HB-EGF mRNA expression in cultures of cells from four of six subjects, but no corresponding change in EGFR protein level was observed. These results indicate that the EGFR signaling pathway is involved in urothelial regeneration. Our data support an autocrine role of HB-EGF in this process and suggest that the EGFR pathway is a potential therapeutic target for modulating urothelial cell proliferation.  相似文献   
96.
Six examples of histologically diagnosed, non-invasive breast carcinomas were studied by electron microscopy to elucidate the ultrastructural features for an accurate diagnosis of in situ carcinoma. The results obtained revealed two patterns of basal lamina/stromal cells relationship. One pattern showed intact basal lamina with associated periductal stromal cells consisting entirely of fibroblasts, the other pattern showed disruption of basal lamina by gaps and malignant cell protrusions with associated stromal cells consisting of both fibroblasts and myofibroblasts. As myofibroblasts are not a component of normal breast stroma but are known to be a prominent feature in the stroma of infiltrating breast carcinoma, the present observations suggest that myofibroblastic proliferation around in situ carcinoma represents an early sign of carcinomatous infiltration. Hence the definitive diagnosis of non-invasive carcinoma of the breast requires an intact basal lamina and a complete absence of a myofibroblastic reaction.  相似文献   
97.
Nasir J 《Clinical genetics》2001,59(5):302-303
  相似文献   
98.
99.
100.

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   
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