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   2043篇
  免费   96篇
  国内免费   5篇
耳鼻咽喉   17篇
儿科学   69篇
妇产科学   105篇
基础医学   165篇
口腔科学   58篇
临床医学   188篇
内科学   469篇
皮肤病学   29篇
神经病学   105篇
特种医学   42篇
外科学   328篇
综合类   32篇
预防医学   251篇
眼科学   31篇
药学   195篇
中国医学   12篇
肿瘤学   48篇
  2023年   22篇
  2022年   46篇
  2021年   88篇
  2020年   48篇
  2019年   82篇
  2018年   80篇
  2017年   64篇
  2016年   60篇
  2015年   71篇
  2014年   111篇
  2013年   109篇
  2012年   155篇
  2011年   141篇
  2010年   89篇
  2009年   76篇
  2008年   124篇
  2007年   100篇
  2006年   79篇
  2005年   87篇
  2004年   83篇
  2003年   89篇
  2002年   61篇
  2001年   24篇
  2000年   35篇
  1999年   26篇
  1998年   16篇
  1997年   5篇
  1996年   5篇
  1994年   5篇
  1992年   11篇
  1991年   13篇
  1990年   10篇
  1989年   5篇
  1988年   11篇
  1987年   6篇
  1986年   10篇
  1985年   4篇
  1984年   5篇
  1983年   4篇
  1979年   7篇
  1977年   4篇
  1976年   7篇
  1975年   8篇
  1974年   6篇
  1973年   10篇
  1971年   4篇
  1970年   3篇
  1967年   3篇
  1966年   3篇
  1965年   4篇
排序方式: 共有2144条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Placental transfer of vitamin E was investigated from 19 to 35 weeks of gestation by analysis of fetal and maternal blood samples for total tocopherol, total lipids, and fetal red blood cell antioxidant reserves. Fifty-two fetal blood samples were obtained under ultrasonographic guide by percutaneous umbilical blood sampling. Thirteen were from fetuses with gestational age less than or equal to 22 weeks (x serum vitamin E = 0.4 +/- 0.14 mg/dl), 12 were from fetuses at 23-27 weeks gestation (x serum vitamin E = 0.4 +/- 0.21 mg/dl), and 27 were from fetuses with gestational age 28-38 weeks (x serum level = 0.37 +/- 0.18). Total lipid levels ranged from 140 to 216 mg/dl. Maternal plasma vitamin E concentrations correlated significantly with concurrent values in the fetus. There were no significant differences in serum vitamin E levels or vitamin E to total lipid ratio in samples from early, mid, or late gestation in either the mother or fetus. Red blood cell antioxidant reserve on samples from 18 fetuses were grossly abnormal by three different functional assays. On the basis of these data, placental transfer of vitamin E appears to be relatively constant through advancing gestation. Red blood cell antioxidant reserve is uniformly low.  相似文献   
6.
7.
8.
Approximately 5% of Americans over age 65, or 1.5 million individuals, currently reside in the nations's 20,000 nursing homes. The authors present material that lead to three conclusions about this population. First, nutritional deficiencies are common underlying causes of adverse clinical outcomes. Second, nutritional deficiencies are frequently not recognized. Third, opportunities for preventing or correcting undernutrition exist, provided that the significant and reversible nature of the nutrient deficiencies are identified.  相似文献   
9.
Physical training is known to induce oxidative stress in individuals subjected to intense exercise. In this study, we investigated plasma malondialdehyde (MDA) levels and erythrocyte superoxide dismutase (SOD) activity of 25 young male footballers and a control group of similar age. Red blood cell (RBC) count, haemoglobin (Hb) and haematocrit (Hct) values, and copper (Cu) and zinc (Zn) levels were also examined. The maximal oxygen uptake (VO2max) of all subjects was determined in order to establish their functional capacity. The main finding of the present study was that plasma MDA levels, one of the most commonly used markers of lipid peroxidation, of this group of footballers aged under 21 decreased slightly when compared with those of the control group (p < 0.001). In contrast, erythrocyte SOD activity was higher in the footballer group than in the controls (p < 0.001). Footballers who are under regular training showed an improved antioxidant activity in comparison to sedentary controls. Plasma copper concentration, RBC count and Hb concentration of the footballer group were all significantly lower than those of the control group, (p < 0.001, p < 0.01, p < 0.01, respectively). Investigating the footballers' data with Spearman's correlation analyses, the correlation coefficients (r) between Zn/Cu ratio and SOD was positive (r=0.44; p < 0.05); and between VO2max and SOD (r=0.42; p < 0.05) were both positive. On the basis of statistical analysis, we suggest that regular exercise may be beneficial in cases of oxidative damage by reducing the amount of lipid peroxidation and increasing the activity of the antioxidant enzyme SOD.  相似文献   
10.
This article describes the identification of a novel locus (DFNB39) responsible for an autosomal recessive form of hearing loss segregating in a Pakistani consanguineous family. The hearing impaired members of this family present with profound prelingual sensorineural hearing impairment and use sign language for communications. Linkage was established to microsatellite markers located on chromosome 7q with a maximum multipoint lod score of 3.8. The region of homozygosity spans a 19 cM region that is bounded by markers D7S3046 and D7S644.  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