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   1069621篇
  免费   70221篇
  国内免费   2828篇
耳鼻咽喉   14943篇
儿科学   33972篇
妇产科学   30550篇
基础医学   149905篇
口腔科学   30555篇
临床医学   86318篇
内科学   222844篇
皮肤病学   24706篇
神经病学   85379篇
特种医学   40340篇
外国民族医学   344篇
外科学   162740篇
综合类   19968篇
一般理论   294篇
预防医学   81287篇
眼科学   23617篇
药学   75738篇
中国医学   2536篇
肿瘤学   56634篇
  2021年   9880篇
  2019年   10433篇
  2018年   14816篇
  2017年   10712篇
  2016年   11164篇
  2015年   12464篇
  2014年   17355篇
  2013年   26390篇
  2012年   37134篇
  2011年   39323篇
  2010年   22976篇
  2009年   21047篇
  2008年   35847篇
  2007年   37997篇
  2006年   37527篇
  2005年   36968篇
  2004年   34831篇
  2003年   33421篇
  2002年   32665篇
  2001年   45806篇
  2000年   47307篇
  1999年   40099篇
  1998年   11085篇
  1997年   9964篇
  1996年   9794篇
  1995年   9047篇
  1994年   8589篇
  1992年   29950篇
  1991年   28589篇
  1990年   27905篇
  1989年   26664篇
  1988年   24737篇
  1987年   24298篇
  1986年   23347篇
  1985年   22122篇
  1984年   16548篇
  1983年   14110篇
  1982年   8492篇
  1979年   15267篇
  1978年   10685篇
  1977年   9029篇
  1976年   8550篇
  1975年   9487篇
  1974年   11282篇
  1973年   10826篇
  1972年   10205篇
  1971年   9457篇
  1970年   9106篇
  1969年   8552篇
  1968年   8157篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The investigation of AUSTROLIABUM CANDIDUM afforded, in addition to several known sesquiterpene lactones, four new ones, including three germacranolides with an ether bridge, as well as an unusual glucoside. The structures were elucidated by spectroscopic methods.  相似文献   
992.
Greater body fatness during childhood is associated with reduced risk of premenopausal breast cancer, but few studies have addressed the relation of adiposity with sex hormones in girls. We prospectively examined associations between adiposity and circulating levels of sex hormones and sex hormone-binding globulin (SHBG) among 286 girls in the Dietary Intervention Study in Children. Participants were 8 to 10 years old at baseline and were followed for an average of 7 years. Anthropometric measurements were taken at baseline and at subsequent annual visits, and blood samples were collected every 2 years. Concentrations of dehydroepiandrosterone sulfate (DHEAS) during follow-up were higher among girls with greater body mass index (BMI) at baseline. The mean for the lowest BMI quartile was 63.0 microg/dL compared with 78.8 microg/dL for the highest quartile, and each kg/m(2) increment in baseline BMI was associated with a 4.3% increase (95% confidence interval, 1.6-7.0%) in DHEAS levels during follow-up (P(trend) = 0.002). Concentrations of SHBG during follow-up were lower among girls with greater BMI at baseline. The mean for the lowest BMI quartile was 94.8 nmol compared with 57.5 nmol for the highest quartile, and each kg/m(2) increment in baseline BMI was associated with an 8.8% decrease (95% confidence interval, 7.0-10.6%) in SHBG levels during follow-up (P(trend) < 0.0001). Estrogen and progesterone concentrations were similar across BMI quartiles. These findings suggest that adiposity may alter DHEAS and SHBG levels in girls. Whether and how these differences affect breast development and carcinogenesis requires further research.  相似文献   
993.
Pituitary metastases of solid tumours are infrequent, specially as a first manifestation. When they happen, they are usually due to breast or lung cancer and are asymptomatic or produce diabetes insipidus. It is very strange that they produce hormonal deficiency. We present a case report of a bronchogenic adenocarcinoma in a 65-year-old man which began with panhypopituitarism, diabetes insipidus and visual alterations. Magnetic resonance imaging revealed a large sellar mass, with clivus infiltration and invading the right cavernous sinus. The biopsy result was adenocarcinoma metastases from lung cancer.  相似文献   
994.
AIM: To determine the influence of Type 1 diabetes mellitus on circulating adipocytokines in children. METHODS: The circulating concentrations of leptin, adiponectin, resistin and tumour necrosis factor (TNF)-alpha were measured in 91 children, aged 11.1 +/- 2.7 years, with Type 1 diabetes mellitus (T1DM). Ninety-one healthy children were selected as control subjects. RESULTS: Body mass index-adjusted leptin concentrations were higher in the pubertal diabetic children compared with the control children. There was a significant positive correlation between leptin and daily insulin dose in the diabetic group. Circulating adiponectin concentrations were higher in the prepubertal diabetic children and were positively associated with HbA(1c). Resistin concentrations were lower in the prepubertal non-diabetic subjects compared with the pubertal non-diabetic children, whose values were higher than those of the diabetic children. TNF-alpha concentrations were similar in non-diabetic and diabetic children. CONCLUSIONS: Circulating concentrations of adipocytokines are abnormal in Type 1 diabetic children, although the direction of change differs by cytokine. Pubertal development, in addition to insulin treatment and glycaemic control, also influences the concentrations.  相似文献   
995.
996.
In their recent review article, Tanvetyanon and Stiff [1] pointedout that hypocalcemia is a frequent side-effect of intravenousbisphosphonates. This adverse event is usually mild and exceptionallysymptomatic, with the principle risk factors being pre-existinghypovitaminosis D, previous parathyroid surgery and intestinalresections. A direct consequence of hypocalcemia  相似文献   
997.
998.
999.
1000.
This case report demonstrates how extracting a maxillary deciduous canine affects the eruption path of a labially displaced ectopically erupting permanent canine. A long-term follow-up is presented, and the biologic mechanisms are discussed.  相似文献   
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