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   44812篇
  免费   3377篇
  国内免费   147篇
耳鼻咽喉   466篇
儿科学   1380篇
妇产科学   1215篇
基础医学   5911篇
口腔科学   491篇
临床医学   8175篇
内科学   8230篇
皮肤病学   713篇
神经病学   4372篇
特种医学   812篇
外国民族医学   1篇
外科学   3494篇
综合类   762篇
一般理论   42篇
预防医学   5173篇
眼科学   883篇
药学   2975篇
中国医学   79篇
肿瘤学   3162篇
  2023年   231篇
  2022年   367篇
  2021年   870篇
  2020年   494篇
  2019年   805篇
  2018年   998篇
  2017年   797篇
  2016年   869篇
  2015年   1071篇
  2014年   1404篇
  2013年   2088篇
  2012年   3032篇
  2011年   3180篇
  2010年   1645篇
  2009年   1625篇
  2008年   2870篇
  2007年   3094篇
  2006年   3182篇
  2005年   3120篇
  2004年   3033篇
  2003年   2846篇
  2002年   2637篇
  2001年   430篇
  2000年   294篇
  1999年   480篇
  1998年   630篇
  1997年   571篇
  1996年   587篇
  1995年   529篇
  1994年   428篇
  1993年   401篇
  1992年   290篇
  1991年   278篇
  1990年   241篇
  1989年   220篇
  1988年   215篇
  1987年   167篇
  1986年   136篇
  1985年   157篇
  1984年   192篇
  1983年   185篇
  1982年   242篇
  1981年   179篇
  1980年   184篇
  1979年   110篇
  1978年   107篇
  1977年   112篇
  1976年   86篇
  1975年   71篇
  1974年   78篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.

Background  

Total hip arthroplasty is a successful surgery, that fails at a rate of approximately 10% at ten years from surgery. Causes for failure are mainly aseptic loosening of one or both components partially due to wear of articular surfaces and partially to design. The present analysis aimed to identify risk factors and quantify their effects on aseptic failure.  相似文献   
62.
63.
64.
African Americans experience household food insecurity, ie, the limited availability of nutritionally adequate and safe food, or ability to acquire acceptable foods in socially acceptable ways, at three times the rate of non-Hispanic whites. Thirty percent of all African-American children live in food-insecure households. The purpose of this study was to identify characteristics associated with household food insecurity among a high-risk postpartum population. Two-hundred six low-income, African-American mother−infant dyads were recruited through the Special Supplemental Nutrition Program for Women, Infants, and Children clinics. The six-item US Department of Agriculture food security scale was used to classify households as food secure, marginally food secure, or food insecure. Multinomial logistic regression was used to estimate the association between selected maternal/household characteristics and household food-security status. Fifty-three percent of households were food secure, 34% were marginally food secure, and 13% were food insecure. Maternal education less than college (relative risk ratio [RRR]=0.46; 95% confidence interval [CI]: 0.22 to 0.98) was inversely associated with marginal food security. Depressive symptoms (RRR=1.09; 95% CI: 1.02 to 1.16) and having the baby's father in the household (RRR=3.46; 95% CI: 1.22 to 9.82) were associated with household food insecurity, while having a grandmother in the household (RRR=0.15; 95% CI: 0.03 to 0.80) was inversely associated with experiencing household food insecurity. Findings from this study suggest that young, low-income, African-American families with only one child are particularly susceptible to experiencing household food insecurity. Intergenerational support and transfer of knowledge can be a key protective attribute among low-income African-American households.  相似文献   
65.
66.
Evidence that genetic disposition for adult lactose intolerance significantly affects calcium intake, bone density, and fractures in postmenopausal women is presented. PCR-based genotyping of lactase gene polymorphisms may complement diagnostic procedures to identify persons at risk for both lactose malabsorption and osteoporosis. INTRODUCTION: Lactase deficiency is a common autosomal recessive condition resulting in decreased intestinal lactose degradation. A -13910 T/C dimorphism (LCT) near the lactase phlorizin hydrolase gene, reported to be strongly associated with adult lactase nonpersistence, may have an impact on calcium supply, bone density, and osteoporotic fractures in the elderly. MATERIALS AND METHODS: We determined LCT genotypes TT, TC, and CC in 258 postmenopausal women using a polymerase chain reaction-based assay. Genotypes were related to milk intolerance, nutritional calcium intake, intestinal calcium absorption, bone mineral density (BMD), and nonvertebral fractures. RESULTS: Twenty-four percent of all women were found to have CC genotypes and genetic lactase deficiency. Age-adjusted BMD at the hip in CC genotypes and at the spine in CC and TC genotypes was reduced by -7% to -11% depending on the site measured (p = 0.04). LCT(T/C-13910) polymorphisms alone accounted for 2-4% of BMD in a multiple regression model. Bone fracture incidence was significantly associated with CC genotypes (p = 0.001). Milk calcium intake was significantly lower (-55%, p = 0.004) and aversion to milk consumption was significantly higher (+166%, p = 0.01) in women with the CC genotype, but there were no differences in overall dietary calcium intake or in intestinal calcium absorption test values. CONCLUSION: The LCT(T/C-13910) polymorphism is associated with subjective milk intolerance, reduced milk calcium intake, and reduced BMD at the hip and the lumbar spine and may predispose to bone fractures. Genetic testing for lactase deficiency may complement indirect methods in the detection of individuals at risk for both lactose malabsorption and osteoporosis.  相似文献   
67.
68.
69.
70.
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