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   1336265篇
  免费   100268篇
  国内免费   4279篇
耳鼻咽喉   16814篇
儿科学   43616篇
妇产科学   36378篇
基础医学   197907篇
口腔科学   35909篇
临床医学   129691篇
内科学   258325篇
皮肤病学   26377篇
神经病学   111978篇
特种医学   48221篇
外国民族医学   366篇
外科学   184223篇
综合类   28783篇
现状与发展   1篇
一般理论   460篇
预防医学   114471篇
眼科学   28990篇
药学   98871篇
  6篇
中国医学   3169篇
肿瘤学   76256篇
  2021年   10916篇
  2019年   11656篇
  2018年   16347篇
  2017年   12311篇
  2016年   13269篇
  2015年   15214篇
  2014年   20834篇
  2013年   32098篇
  2012年   44298篇
  2011年   46981篇
  2010年   27126篇
  2009年   24966篇
  2008年   42804篇
  2007年   45114篇
  2006年   45245篇
  2005年   43667篇
  2004年   41616篇
  2003年   39556篇
  2002年   38364篇
  2001年   60860篇
  2000年   62530篇
  1999年   52297篇
  1998年   14592篇
  1997年   13285篇
  1996年   13124篇
  1995年   12462篇
  1994年   11627篇
  1993年   10924篇
  1992年   41569篇
  1991年   40760篇
  1990年   39448篇
  1989年   37342篇
  1988年   34587篇
  1987年   33699篇
  1986年   32158篇
  1985年   30647篇
  1984年   23037篇
  1983年   19593篇
  1982年   11758篇
  1979年   20805篇
  1978年   14816篇
  1977年   12065篇
  1976年   11876篇
  1975年   12112篇
  1974年   14800篇
  1973年   14474篇
  1972年   13358篇
  1971年   12419篇
  1970年   11486篇
  1969年   10414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