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   1453694篇
  免费   105863篇
  国内免费   4366篇
耳鼻咽喉   18747篇
儿科学   47776篇
妇产科学   39188篇
基础医学   215334篇
口腔科学   39858篇
临床医学   139586篇
内科学   279248篇
皮肤病学   29802篇
神经病学   123823篇
特种医学   53208篇
外国民族医学   366篇
外科学   202303篇
综合类   29326篇
现状与发展   1篇
一般理论   494篇
预防医学   120777篇
眼科学   31635篇
药学   106904篇
  6篇
中国医学   3358篇
肿瘤学   82183篇
  2021年   12053篇
  2019年   12885篇
  2018年   18887篇
  2017年   14508篇
  2016年   16128篇
  2015年   17632篇
  2014年   23519篇
  2013年   36836篇
  2012年   50375篇
  2011年   53780篇
  2010年   31013篇
  2009年   27548篇
  2008年   49743篇
  2007年   52450篇
  2006年   52274篇
  2005年   50648篇
  2004年   48218篇
  2003年   46144篇
  2002年   44861篇
  2001年   64959篇
  2000年   67712篇
  1999年   55212篇
  1998年   15843篇
  1997年   14307篇
  1996年   13916篇
  1995年   13131篇
  1994年   12284篇
  1993年   11525篇
  1992年   42168篇
  1991年   41256篇
  1990年   39916篇
  1989年   37845篇
  1988年   35010篇
  1987年   34178篇
  1986年   32538篇
  1985年   31209篇
  1984年   23584篇
  1983年   20046篇
  1982年   12238篇
  1981年   10749篇
  1979年   21215篇
  1978年   15191篇
  1977年   12459篇
  1976年   12236篇
  1975年   12459篇
  1974年   15132篇
  1973年   14756篇
  1972年   13588篇
  1971年   12678篇
  1970年   11722篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Most attempts to tissue-engineer cartilage have involved seeding of cultured cells into a biological or synthetic scaffold. We have developed a novel two-step culture approach that makes possible the in vitro formation of cartilaginous-like tissue by mature adult bovine chondrocytes without the aid of a synthetic matrix. The first step consists of culturing chondrocytes under conditions that maintain their rounded shape and their molecular phenotype as assessed by type II collagen and aggrecan production. This step was accomplished by culturing the isolated chondrocytes in alginate beads until the cells have reestablished a proteoglycan-rich cell-associated matrix (CM). The second step consists of culturing the cells with their CM, after recovery from the beads, on a tissue culture insert with a porous membrane. In this study, young adult bovine articular chondrocytes were cultured in alginate beads in the presence of 10% or 20% fetal bovine serum (FBS). After 7 days of culture, the alginate beads were dissolved by incubating the beads for 20 min in sodium citrate buffer, a calcium chelator. Following a brief centrifugation, the cells with their CM were recovered, resuspended in medium containing 10% or 20% FBS and seeded onto a tissue culture insert. After 1 week of culture on the insert, the individual cells with their CM progressively became incorporated into a mass of cartilaginous tissue. Culture with 20% FBS resulted in the best formation of tissues. These tissues, easily recovered from the insert, were then subjected to biochemical and histological analyses. The biochemical results showed that the chondrocytes remain phenotypically stable in the tissues. The de novo tissue has a relatively high ratio of PG/collagen. Histological examination of the tissue revealed it contained a cartilage-like matrix strongly stained with toluidine blue. This scaffold-free system appears ideal to study, in vitro, the development of transplantable cartilaginous tissue.  相似文献   
102.
103.
Most authors consider the principal advantage of FG anastomoses (compared to microsurgical anastomoses) to be shorter operating time, reduced surgical trauma to oviduct stumps, and absence of tissue ischemia. These features promote reparative regeneration and decrease adhesion formation, resulting in complete recanalization of fallopian tubes. To date, the majority of work on FG is confined to the experimental development of surgical techniques. Investigations in reconstructive gynecological surgery are quite uncommon. The physical properties of FG and the positive results of available experimental studies suggest that further development of surgical techniques using FG in obstetrics and gynecology is worthwhile.  相似文献   
104.
105.
The Authors examine the correlation between hypertensive disorders of pregnancy and fetal growth. The results of a study of 342 pregnancies, confirm a significant correlation between hypertension and fetal growth retardation. These findings, so evident in moderate and severe hypertension, have also been confirmed in cases of mild hypertension. The medical treatment also in the pregnancies with mild hypertension, and a larger utilisation of operative deliveries, determined a decrease in perinatal mortality and morbidity.  相似文献   
106.
The decoction of Sclerocarya birroea Hochst. shows hypoglycaemic effects, an increase in plasma IRI in normal rats and an incremented oral-glucose tolerance. The decoction is also active against diet-induced hypercholesterolaemia.  相似文献   
107.
108.
109.
110.
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