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   8919篇
  免费   628篇
  国内免费   16篇
耳鼻咽喉   63篇
儿科学   367篇
妇产科学   266篇
基础医学   1010篇
口腔科学   112篇
临床医学   2024篇
内科学   1156篇
皮肤病学   97篇
神经病学   902篇
特种医学   184篇
外科学   681篇
综合类   113篇
一般理论   27篇
预防医学   1293篇
眼科学   135篇
药学   534篇
中国医学   41篇
肿瘤学   558篇
  2023年   51篇
  2022年   62篇
  2021年   172篇
  2020年   118篇
  2019年   161篇
  2018年   192篇
  2017年   194篇
  2016年   198篇
  2015年   198篇
  2014年   279篇
  2013年   409篇
  2012年   652篇
  2011年   710篇
  2010年   388篇
  2009年   341篇
  2008年   613篇
  2007年   656篇
  2006年   594篇
  2005年   591篇
  2004年   643篇
  2003年   547篇
  2002年   517篇
  2001年   96篇
  2000年   98篇
  1999年   91篇
  1998年   111篇
  1997年   78篇
  1996年   74篇
  1995年   65篇
  1994年   64篇
  1993年   51篇
  1992年   40篇
  1991年   43篇
  1990年   28篇
  1989年   43篇
  1988年   21篇
  1987年   35篇
  1986年   20篇
  1985年   30篇
  1984年   26篇
  1983年   36篇
  1982年   34篇
  1981年   25篇
  1980年   27篇
  1979年   18篇
  1978年   24篇
  1977年   14篇
  1976年   15篇
  1975年   14篇
  1974年   12篇
排序方式: 共有9563条查询结果,搜索用时 15 毫秒
991.
992.
Neural tube defects are among the most common and serious birth defects. Most of these defects are caused by multifactorial inheritance. Research over the past decade has led to advances in understanding the etiology of these congenital anomalies. Folic acid has been shown to reduce the risk of first-time occurrence of neural tube defects as well as recurrent risk. Other genetic and environmental factors are under investigation. In this article, the nurse's role in the primary prevention of these birth defects is described.  相似文献   
993.
994.
Nutrient intakes of 2149 black and white, 9- and 10-year-old girls varied by race, household income, and parental education. Of the three variables, higher education was most consistently associated with more desirable levels of nutrient intakes, that is, lower percentage of dietary fat and higher levels of vitamin C, calcium, and potassium. Higher income was related to higher intakes of vitamin C, but lower intakes of calcium and iron. Higher income was associated with lower percentage of dietary fat. After adjustment for income and education, race was associated with intakes of calcium, vitamin C, and to a lesser extent, percentages of kilocalories from total fat and polyunsaturated fat, and potassium. Black girls had a significantly lower intake of calcium (720 versus 889 mg) and a higher intake of vitamin C (91 versus 83 mg).Proportions of the cohort with inadequate or excessive intakes of micronutrients and macronutrients were also estimated. A high proportion of girls exceeded the recommended intake level of 30% of kilocalories from total fat (90% of black girls; 84% of white girls) and 10% of kilocalories from saturated fat (92 and 93%, respectively). Low intakes of calcium (40% of black girls and 20% of white girls) and zinc (36 and 38%, respectively) commonly were found for girls of both races.  相似文献   
995.
996.
997.
Background:  Previous research suggests children use different types of attribution to explain bullying. The research, however, has not explored links between children's attributions.
Method:  This study explores the types of, and links between, attributions made by children about bullying situations. Seventeen 9- and 10-year-olds were interviewed at school. Types of attributions and links between attributions were categorised using content analysis.
Results:  The results suggest that children make a range of linked attributions that can be coded into characterological and behavioural and a new category named 'feelings'.
Conclusions:  The findings are linked to previous research, and implications for clinical and school interventions are discussed.  相似文献   
998.
We describe a convenient, efficient, semiautomated protocol for assaying large numbers of DNA samples for over 20 mutations causing cystic fibrosis. The protocol uses the following: (1) a programmable robotic workstation to perform rapid pipetting and dot-blotting operations, (2) an allele-specific oligonucleotide hybridization in a single water bath without correcting for G + C content of oligonucleotides, and (3) a combinatorial system that allows direct determination of the genotype for more frequent mutations. We have used this system routinely for 16 months for carrier detection and for diagnosis of cystic fibrosis. The method can be readily applied to any combination of allele-specific oligonucleotide assays whether for multiple alleles at one locus or for a few alleles at multiple loci. © 1994 Wiley-Liss, Inc.  相似文献   
999.
Thrombospondin (TSP) is an extracellular matrix molecule that has been previously associated with neural development and neurite outgrowth in vitro. Little is known, however, about the expression of TSP in the adult nervous system. In this study, TSP localization was examined in nervous tissue from adult mouse, goldfish, newt, and adult and juvenile Xenopus. TSP was associated with neurons in the brains of all species examined. TSP was present in central nerve tracts capable of regeneration, such as the goldfish, Xenopus, and newt optic nerves, but was absent from tracts not capable of regeneration, such as the mouse optic nerve. TSP was also present in the neuropil of goldfish and newt spinal cord, but was restricted to motor neurons in mice and adult Xenopus. In addition, TSP was observed in sciatic nerves of mice, Xenopus, and newt. These results indicate a correlation between the presence of TSP and the potential for successful nerve regeneration across a wide range of animal classes. © Wiley-Liss, Inc.  相似文献   
1000.
This study was a 1-year follow-up of a cohort of 52 women who underwent trans-obturator tape (TOT) procedures using Obtape. Follow-up information was available for 45/52 (87%) women. The rate of erosions was 8/52 (15%). Among 34 women examined, 26% experienced tenderness on palpation of operative site, and 72% were objectively cured on pad test. Forty women completed questionnaires (median Incontinence Impact Questionnaire-7, 0; median Urogenital Distress Inventory-6, 17) and of those, 93% would recommend TOT to a friend. We found a high rate of erosions among our cohort. Our high rate of erosions may be a result of our review of the majority of the cohort, and it is likely related to the specific device used (Obtape). The majority of women were satisfied with the outcome. Before introducing new procedures into widespread clinical practice, it is important to rigorously investigate their outcomes.  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