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   1335174篇
  免费   100207篇
  国内免费   4272篇
耳鼻咽喉   16797篇
儿科学   43584篇
妇产科学   36357篇
基础医学   197823篇
口腔科学   35905篇
临床医学   129554篇
内科学   258084篇
皮肤病学   26376篇
神经病学   111867篇
特种医学   48170篇
外国民族医学   366篇
外科学   184022篇
综合类   28775篇
现状与发展   1篇
一般理论   460篇
预防医学   114364篇
眼科学   28980篇
药学   98821篇
  6篇
中国医学   3167篇
肿瘤学   76174篇
  2021年   10905篇
  2019年   11631篇
  2018年   16316篇
  2017年   12285篇
  2016年   13248篇
  2015年   15193篇
  2014年   20799篇
  2013年   32060篇
  2012年   44240篇
  2011年   46881篇
  2010年   27071篇
  2009年   24920篇
  2008年   42714篇
  2007年   45053篇
  2006年   45168篇
  2005年   43590篇
  2004年   41555篇
  2003年   39493篇
  2002年   38302篇
  2001年   60842篇
  2000年   62513篇
  1999年   52275篇
  1998年   14579篇
  1997年   13274篇
  1996年   13115篇
  1995年   12459篇
  1994年   11626篇
  1993年   10920篇
  1992年   41568篇
  1991年   40759篇
  1990年   39444篇
  1989年   37341篇
  1988年   34581篇
  1987年   33693篇
  1986年   32150篇
  1985年   30638篇
  1984年   23035篇
  1983年   19589篇
  1982年   11752篇
  1979年   20804篇
  1978年   14814篇
  1977年   12064篇
  1976年   11876篇
  1975年   12110篇
  1974年   14800篇
  1973年   14472篇
  1972年   13356篇
  1971年   12418篇
  1970年   11485篇
  1969年   10410篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
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   
93.
94.
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   
95.
96.
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   
97.
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   
98.
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