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   33369篇
  免费   2605篇
  国内免费   58篇
耳鼻咽喉   164篇
儿科学   1234篇
妇产科学   999篇
基础医学   4086篇
口腔科学   515篇
临床医学   5191篇
内科学   6719篇
皮肤病学   612篇
神经病学   3321篇
特种医学   586篇
外科学   2777篇
综合类   543篇
一般理论   30篇
预防医学   4499篇
眼科学   553篇
药学   2028篇
中国医学   36篇
肿瘤学   2139篇
  2023年   218篇
  2022年   283篇
  2021年   521篇
  2020年   432篇
  2019年   687篇
  2018年   785篇
  2017年   610篇
  2016年   638篇
  2015年   737篇
  2014年   1040篇
  2013年   1573篇
  2012年   2363篇
  2011年   2300篇
  2010年   1277篇
  2009年   1199篇
  2008年   1960篇
  2007年   2166篇
  2006年   2026篇
  2005年   2096篇
  2004年   1977篇
  2003年   1777篇
  2002年   1775篇
  2001年   528篇
  2000年   449篇
  1999年   449篇
  1998年   405篇
  1997年   297篇
  1996年   274篇
  1995年   280篇
  1994年   235篇
  1993年   208篇
  1992年   305篇
  1991年   275篇
  1990年   291篇
  1989年   260篇
  1988年   247篇
  1987年   260篇
  1986年   252篇
  1985年   246篇
  1984年   222篇
  1983年   160篇
  1982年   149篇
  1981年   135篇
  1980年   130篇
  1979年   142篇
  1978年   143篇
  1977年   109篇
  1975年   96篇
  1974年   95篇
  1972年   87篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
Such research evidence as exists on effective drug strategies in prevention and education draws attention to the importance of involving parents along with other community agencies and school governors. Much depends nevertheless on the way in which 'involvement' is interpreted and the assumptions that are made about parents' knowledge of drugs and drug education as well as their attitudes to drug issues. As the age of initial experimentation and contact with drugs continues to fall, the importance of enskilling parents to support drug education programmes for 5 year olds and upwards continues to rise. This paper reports the first wide ranging survey of parents' knowledge of drugs and drug issues across an entire English county embracing younger as well as older children. The need for more coordinated, informed and systematic guidance to parents is established.  相似文献   
25.
The relations between three hormones of the hypothalamic-pituitary-adrenocortical (HPA) axis, beta-endorphin (β-EP), corticotropin-releasing hormone (CRH) and cortisol, and mood change were examined in 11 elite runners and 12 highly trained meditators matched in age, sex, and personality. Despite metabolic differences between running and meditation, we predicted that mood change after these activities would be similar when associated with similar hormonal change. Compared to pre-test and control values, mood was elevated after both activities but not significantly different between the two groups at post-test. There were significant elevations of β-EP and CRH after running and of CRH after meditation, but no significant differences in CRH increases between groups. CRH was correlated with positive mood changes after running and meditation. Cortisol levels were generally high but erratic in both groups. We conclude that positive affect is associated with plasma CRH immunoreactivity which itself is significantly associated with circulating β-EP supporting a role for CRH in the release of β-EP. Increased CRH immunoreactivity following meditation indicates, however, that physical exercise is not an essential requirement for CRH release.  相似文献   
26.
The goals of this study were to investigate muscle fatigue in patients with multiple sclerosis (MS), and to determine the relationships between muscle fatigue, clinical status, and perceived fatigue. The fatigability of the anterior tibial muscle was quantitated in patients and controls during 9 min of intermittent stimulation (used to eliminate central sources of muscle fatigue). During exercise, the decline in tetanic force, phosphocreatine, and intracellular pH was greater in patients than in controls. The compound muscle action potential amplitude did not decrease during exercise, indicating that there was no failure of neuromuscular transmission during fatigue. Thus, the excessive fatigue in MS developed from sources beyond the muscle membrane. Following exercise, the recovery of tetanic force was delayed in patients (a pattern that suggests abnormal excitation–contraction coupling), whereas the recovery of metabolites was complete in both groups. Muscular fatigue was correlated with clinical disability but not with perceived fatigue. These results suggests that fatigue in MS has both central (perception, upper motor neuron dysfunction) and peripheral (impaired metabolism and excitation–contraction coupling) components.© 1995 John Wiley &Sons, Inc.  相似文献   
27.
Summary It has been suggested that inherited traits play a role in the development of osteoporosis by providing a background for the modulation of gene expression. In this study, we examine the influence of the different alleles of alpha2-HS glycoprotein (AHSG), a protein of the bone matrix, on quantitative estrogens, estrone and estradiol, and bone measures, bone area and density. Estrogens provide a protective effect against fractures in older women and were thus included in the analyses. Isoelectric focusing of AHSG from sera followed by immunoblotting was used to type 163 white post-menopausal women participating in a clinical trial of the effects of walking on bone loss. Plasma hormones were measured by a combination of extraction, column chromatography, and radioimmunoassay; bone measures on the dominant radius were determined with computerized tomography. Analysis of variance was done on estrogen and bone measures after controlling for the effects of age and body mass index. The two major alleles of AHSG result in three phenotypes, designated AHSG 1-1, AHSG 2-1, and AHSG 2-2. The AHSG 1-1 homozygote showed a decreased concentration of estradiol, the AHSG 2-2 homozygote showed an increased concentration, and the AHSG 2-1 heterozygote was intermediate (P=0.001). Estrone demonstrated a similar pattern in residual analysis although it did not reach statistical significance.  相似文献   
28.
Variation amongst Achromobacter-like strains was examined by DNA restriction endonuclease digestion and rDNA gene patterns generated using a non-radioactive probe. Chromosomal DNA was extracted from 12 cultures representing Achromobacter groups B, E and F, all from human blood cultures. DNA fingerprinting using EcoRI, Hae III or HindIII sub-divided the strains in a similar manner to that obtained by their protein patterns. The HaeIII patterns, with their small number of bands, were the easiest to interpret. The EcoRI patterns included a species-species triplet of bands but minor band patterns allowed further differentiation. The Achromobacter group F strains comprised a separate taxon and were distinct from the group B and E strains by all techniques examined. The study demonstrates that, in addition to total DNA digest analysis, rDNA gene restriction patterns provide a simple but discriminatory electrophoretic method for distinguishing within Achromobacter groups B and E.  相似文献   
29.
30.
One thousand two hundred and fifty-four adolescents in Hamilton, New Zealand, ranging in age from 10 to 16, were questioned on their awareness of, and attitudes towards, cigarette advertising, and on their image of the young smoker. Most of the respondents felt that tobacco companies advertise to encourage people to buy their brands. Smokers were less likely than non-smokers to feel that cigarette companies advertise to encourage young people to take up smoking. They were also more likely to agree that cigarette companies are generous, public spirited people. Non-smokers were more likely to feel that cigarette advertising was effective in encouraging young people to smoke. Winfield, the most popular brand among smokers, was also the most well known. Smokers had a more positive image than non-smokers of the young person who smokes.  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