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   1351365篇
  免费   101506篇
  国内免费   4319篇
耳鼻咽喉   16936篇
儿科学   44028篇
妇产科学   36723篇
基础医学   199791篇
口腔科学   36437篇
临床医学   131820篇
内科学   261038篇
皮肤病学   26552篇
神经病学   113230篇
特种医学   48572篇
外国民族医学   366篇
外科学   185987篇
综合类   29033篇
现状与发展   1篇
一般理论   479篇
预防医学   116459篇
眼科学   29207篇
药学   99745篇
  6篇
中国医学   3182篇
肿瘤学   77598篇
  2021年   11242篇
  2019年   12026篇
  2018年   16767篇
  2017年   12628篇
  2016年   13607篇
  2015年   15593篇
  2014年   21368篇
  2013年   32858篇
  2012年   45422篇
  2011年   48062篇
  2010年   27732篇
  2009年   25505篇
  2008年   43685篇
  2007年   46217篇
  2006年   46202篇
  2005年   44638篇
  2004年   42484篇
  2003年   40355篇
  2002年   39093篇
  2001年   61072篇
  2000年   62741篇
  1999年   52508篇
  1998年   14770篇
  1997年   13419篇
  1996年   13223篇
  1995年   12584篇
  1994年   11731篇
  1993年   11003篇
  1992年   41689篇
  1991年   40880篇
  1990年   39542篇
  1989年   37418篇
  1988年   34675篇
  1987年   33802篇
  1986年   32231篇
  1985年   30718篇
  1984年   23119篇
  1983年   19660篇
  1982年   11820篇
  1979年   20853篇
  1978年   14859篇
  1977年   12090篇
  1976年   11907篇
  1975年   12140篇
  1974年   14824篇
  1973年   14502篇
  1972年   13379篇
  1971年   12435篇
  1970年   11511篇
  1969年   10419篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
91.
92.
Three hundred and twenty samples of subgingival plaque were obtained from 80 caucasian girls, ranging from 10 to 13 years of age. The samples were analyzed to verify the influence of age upon colonization of the gingival sulcus by microorganisms potentially pathogenic to the periodontal tissues. The gingival and plaque status were evaluated through the gingival index (GI) and plaque index (PlI) and the microflora was assessed by the enzymatic method benzoyl-arginine-naphthylamide (BANA). The results of the BANA test were positive for 62.50% of the tested individuals and 40% of the examined sites. The influence of age was statistically significant on BANA reactivity, and the number of positive sites was greater at 11 (57.5%) than at 12 years (28.8%).  相似文献   
93.
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   
94.
95.
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   
96.
97.
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   
98.
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   
99.
100.
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