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   1335527篇
  免费   100240篇
  国内免费   4272篇
耳鼻咽喉   16798篇
儿科学   43588篇
妇产科学   36390篇
基础医学   197879篇
口腔科学   35913篇
临床医学   129579篇
内科学   258097篇
皮肤病学   26380篇
神经病学   111897篇
特种医学   48179篇
外国民族医学   366篇
外科学   184149篇
综合类   28793篇
现状与发展   1篇
一般理论   463篇
预防医学   114395篇
眼科学   28982篇
药学   98837篇
  6篇
中国医学   3167篇
肿瘤学   76180篇
  2021年   10905篇
  2019年   11636篇
  2018年   16320篇
  2017年   12292篇
  2016年   13246篇
  2015年   15195篇
  2014年   20803篇
  2013年   32061篇
  2012年   44250篇
  2011年   46900篇
  2010年   27087篇
  2009年   24930篇
  2008年   42719篇
  2007年   45065篇
  2006年   45174篇
  2005年   43613篇
  2004年   41581篇
  2003年   39501篇
  2002年   38313篇
  2001年   60858篇
  2000年   62523篇
  1999年   52282篇
  1998年   14583篇
  1997年   13283篇
  1996年   13119篇
  1995年   12459篇
  1994年   11630篇
  1993年   10923篇
  1992年   41574篇
  1991年   40760篇
  1990年   39450篇
  1989年   37346篇
  1988年   34588篇
  1987年   33697篇
  1986年   32158篇
  1985年   30650篇
  1984年   23043篇
  1983年   19592篇
  1982年   11754篇
  1979年   20810篇
  1978年   14817篇
  1977年   12068篇
  1976年   11879篇
  1975年   12117篇
  1974年   14808篇
  1973年   14478篇
  1972年   13363篇
  1971年   12423篇
  1970年   11486篇
  1969年   10417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