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   944337篇
  免费   65649篇
  国内免费   2352篇
耳鼻咽喉   11835篇
儿科学   29406篇
妇产科学   22023篇
基础医学   141482篇
口腔科学   24346篇
临床医学   87743篇
内科学   184705篇
皮肤病学   19341篇
神经病学   72494篇
特种医学   33670篇
外国民族医学   87篇
外科学   140723篇
综合类   18127篇
现状与发展   2篇
一般理论   470篇
预防医学   71899篇
眼科学   22599篇
药学   70130篇
  9篇
中国医学   2698篇
肿瘤学   58549篇
  2021年   10494篇
  2019年   10392篇
  2018年   13434篇
  2017年   10271篇
  2016年   11472篇
  2015年   12994篇
  2014年   18381篇
  2013年   26566篇
  2012年   37418篇
  2011年   39275篇
  2010年   22711篇
  2009年   20863篇
  2008年   35646篇
  2007年   38011篇
  2006年   38325篇
  2005年   36855篇
  2004年   35358篇
  2003年   33236篇
  2002年   31783篇
  2001年   38316篇
  2000年   38410篇
  1999年   32576篇
  1998年   10780篇
  1997年   9093篇
  1996年   9045篇
  1995年   8609篇
  1994年   7774篇
  1993年   7097篇
  1992年   24173篇
  1991年   24006篇
  1990年   23276篇
  1989年   23005篇
  1988年   20962篇
  1987年   20329篇
  1986年   19379篇
  1985年   18217篇
  1984年   13853篇
  1983年   11830篇
  1982年   7231篇
  1981年   6531篇
  1979年   12192篇
  1978年   8852篇
  1977年   7441篇
  1976年   7165篇
  1975年   7717篇
  1974年   8945篇
  1973年   8514篇
  1972年   7994篇
  1971年   7386篇
  1970年   7111篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Study of the dynamics of cardiac output in rats with different tolerance to acute massive blood loss showed that the pumping ability of the heart remains intact during the entire posthemorrhagic period in all high-resistant and in 65% low-resistant rats. In 35% rats that were low-resistant to blood loss, the cardiac output deficiency syndrome developed after cessation of bleeding against the background fall in arterial pressure and a decrease in the hepatic blood flow, which are the signs of rapid variant of the dysfunction produced by acute blood loss. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 10, pp. 384–388, October, 1998  相似文献   
992.
Abstract Several previous studies have evaluated the effects of 0.12% chlorhexidine digluconate (ChD) mouthrinses on plaque and gingival inflammation. However, previously, none have been based in general dental practices. The aim of this study was to evaluate the potential to conduct controlled periodontal clinical trials in co-operation with general dental practitioners (gdps). The project took place in 5 general dental practices in the South of England. 121 healthy subjects (24 at 4 sites and 25 at the 5th). aged 18-65 years, mean 35 ± 12) years participated in a double-blind, randomised study during which they received full mouth assessments for plaque and gingival bleeding at baseline, 6 and 12 weeks. 60 subjects were randomly asigned to use the 0.12% ChD mouth wash and 6i the placebo. The assessments were carried out by 5 gpds, who had previously achieved inter-examiner κ scores of 0.78–0.85 (mean 0.81) for the plaque index (PlI), and of 0.73–0.94 (mean 0.87) for a modified gingival index (mGI), and who maintained κ scores of 0.51–0.90 for PII and of 0.73–1.00 for mGI during the 12 months required to complete the study. 98 subjects (48 ChD and 50 placebo) completed the study. Even though the baseline levels of plaque and gingivitis were low, by week 12, mean whole mouth piaque score of the ChD mouthwash users had fallen from 1.33 at baseline to 0.96 and was significantly lower (p < 0.001) than for the placebo users, 1.31 at baseline to 1.13. Whole-mouth gingival bleeding score fell from 0.56 to 0.42 in the ChD mouthwash group but was unchanged (0.54–0.55) in the placebo group. A subsidiary data analysis which considered the effects at sites indicated that within these overall differences, the ChD users experienced almost 2× the reduction from plaque score 2 at baseline at proximal molar sites over a 12-week period (50.6% ChD versus 27.6% placebo). It was concluded that 0.12% ChD mouthwash reduced plaque accumulation fay 28% and gingival inflammation by 25% over a 12–week period, that it is feasible for a group of gdps to maintain high levels of inter–examiner consistency in the use of PlI and mGI, that it is also feasible to carry out such a multicentre study in general dental practice, and that the use of mean mouth scores per subject to analyse the effects of mouthrinses may well mask variations in response throughout the mouth.  相似文献   
993.
Between 1992 and 1995 a series of studies was undertaken to assess the long-term suitability of pyrethroid-impregnated bednets (PIBs) for malaria control in Afghan refugee communities in two villages in North-West Frontier Province, Pakistan. During 1992, 86% of bednet owners volunteered to have their bednets re-impregnated, and a further 15% of families purchased nets at two-thirds of cost price. From 1992 onwards, 27% of the villagers returned to Afghanistan, and annual house spraying campaigns were introduced to protect those still resident but sleeping without bednets. Within 3 years, these campaigns, together with PIBs, reduced the annual incidence of malaria by 87%, from 597 to 78 cases per 1000 population. Nevertheless, 65% of resident families continued to re-impregnate their nets annually with permethrin. To assess whether PIBs were still being used and were still protective, in view of these reduced transmission rates, we carried out a case--control study in 1994 on febrile or otherwise symptomatic patients presenting at village health centres. Comparison of the slide-positivity rates of PIB users and those without bednets showed that regular usage reduced the odds of contracting falciparum and vivax malaria to 0.22 (95% confidence interval (CI): 0.09-0.55) and 0.31 (95% CI: 0.19-0.51), respectively. There was no evidence of a sex- or age-bias in bednet use or in protective effect. The results indicate that a community-based PIB programme is an appropriate malaria control measure in areas where management or security problems make traditional house-spraying campaigns impossible. A relevant finding for those involved in the monitoring of bednet distribution projects is that the local coverage of bednets and the local impact on malaria, even when introduced to remote areas, can be estimated very cheaply by health centre microscopists who simply catalogue blood film diagnoses according to patients'' bednet use practices.  相似文献   
994.
995.
The health, growth and development of a cohort of children (n = 59) aged 6 months to 4 years and born after oocyte donation (OD) was compared with that from a group of children born after in-vitro fertilization (IVF) (n = 126). The study was performed by questionnaire, and the response rate was 100% in the OD group and 95% in the IVF group. All OD children were healthy. Three IVF children had a neurological disorder. Surgical intervention had been carried out in 8% of the OD and 13% of the IVF children. Height and weight development were normal, and eating and sleeping disorders were uncommon in both groups of children. The IVF mothers more often expressed concern about the child's behaviour than did the OD mothers. Thirty-eight percent of the OD parents and 60% of the IVF parents intended to tell the child about the nature of its conception (P < 0.01). Although oocyte recipients appear to have more complications during their pregnancies than conventional IVF patients, the general health status of OD children aged <5 years is at least as good as that of IVF children. Growth and development in both groups of children is similar to that of the general population.   相似文献   
996.
997.
The dipeptides Gly-Pro and Pro-Gly, glycine, and proline do not affect contractile activity of the Straub cardiac preparation of the frog. Gly-Pro and glycine augment, while Pro-Gly moderates the effects of acetylcholine. The effect of proline was insignificant. Equimolar amino acid mixtures and mixtures of the dipeptides decrease the effects of acetylcholine. Direction and the degree of Gly-Pro effect attests to specific action of this peptide on cardiac activity. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 8, pp. 139–141, August, 1998  相似文献   
998.
999.
蓖麻油引产餐对妊娠大鼠分娩的影响   总被引:5,自引:0,他引:5  
目的蓖麻油引产餐用于妊娠晚期引产效果明显,但其作用机制不清楚。本研究通过引产餐灌服妊娠大鼠建立动物引产模型,以期了解引产餐对妊娠大鼠分娩启动和产程的影响,并初步探讨蓖麻油引产餐活性成份。方法于大鼠妊娠第18~20天灌服引产餐,观察大鼠分娩启动和分娩产程变化。利用高压液相分析蓖麻油和蓖麻油引产餐中脂肪酸成份。结果引产餐可提前妊娠大鼠分娩启动时间,缩短分娩产程。蓖麻油引产餐和蓖麻油两者脂肪酸对比结果显示,成份相同,蓖麻酸均占90%,未见花生四烯酸成份。结论引产餐对妊娠晚期大鼠具有引产、催产作用,可以利用引产餐灌服妊娠大鼠建立动物引产模型。推测蓖麻酸是引产餐启动分娩和缩短产程的活性物质。  相似文献   
1000.
Social violence is a kind of violence which is applied by one individual to another. It is a stake in the field of public health because of an increasing number of children with such behaviors. In addition to environmental factors, the occurrence of abnormal social behavior before 9 years of age seems to precede social violence for the subsequent 20 years of life. One must therefore identify an inadequate attitude towards the parents and/or the teachers, or a poor child's self-esteem and self-respect. These phenomena are based on parental authority, on the ethical development of the child, on his verbalization capacity, on his socialization and his affective development. It is therefore important to stimulate ethical capacities and feelings in the child not only to provide autonomy but also to allow reflexive distinction of language, behavior and judgment, which enable him to understand, consider and respect other individuals.  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