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   92398篇
  免费   29990篇
  国内免费   1061篇
耳鼻咽喉   2382篇
儿科学   2540篇
妇产科学   2227篇
基础医学   1921篇
口腔科学   5006篇
临床医学   25472篇
内科学   23595篇
皮肤病学   3210篇
神经病学   11759篇
特种医学   3534篇
外科学   17280篇
综合类   113篇
现状与发展   40篇
预防医学   12933篇
眼科学   2057篇
药学   825篇
中国医学   5篇
肿瘤学   8550篇
  2024年   541篇
  2023年   5000篇
  2022年   1053篇
  2021年   2610篇
  2020年   5247篇
  2019年   1900篇
  2018年   6748篇
  2017年   7229篇
  2016年   7802篇
  2015年   7878篇
  2014年   10239篇
  2013年   11875篇
  2012年   3367篇
  2011年   3116篇
  2010年   6623篇
  2009年   8926篇
  2008年   3156篇
  2007年   2083篇
  2006年   3273篇
  2005年   1834篇
  2004年   1238篇
  2003年   942篇
  2002年   869篇
  2001年   1782篇
  2000年   1107篇
  1999年   1651篇
  1998年   2061篇
  1997年   1904篇
  1996年   1959篇
  1995年   1692篇
  1994年   1081篇
  1993年   911篇
  1992年   729篇
  1991年   617篇
  1990年   495篇
  1989年   516篇
  1988年   502篇
  1987年   381篇
  1986年   352篇
  1985年   292篇
  1984年   247篇
  1983年   295篇
  1982年   225篇
  1981年   202篇
  1980年   120篇
  1978年   120篇
  1977年   119篇
  1976年   88篇
  1974年   70篇
  1972年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
In the past decade, speech-language pathologists have taken a leading role in the management of services for patients with oropharyngeal dysphagia. This article presents the historical perspective of this role, the rationale for assuming the responsibility, and suggests directions for continued involvement.  相似文献   
982.
983.
Building on the foundation of understanding and comprehensive assessment of battered women, this article addresses service planning and intervention. Strategies are approached within the framework of a Crisis Paradigm developed from field research with battered women and their families. They include mechanisms such as support groups which link crisis service to the long-term needs of battered women, and systematic approaches to removing the obstacles which keep women victimized. An Assessment and Service Planning Guide (ASPG) is proposed for inclusion in routine health care of abused women. The article concludes with strategies for preventing violence at interpersonal and societal levels.  相似文献   
984.
985.
The effect of electrical dysrhythmias on the mechanical activity of the fed stomach was investigated in 5 conscious dogs implanted with Ag-AgCl electrodes and strain gauge force transducers. Each dog was fed 1 can of ALPO® and electromechanical activities of the stomach were recorded for the next 120 min. The results show that intraarterial boluses of met-enkephalin (75 g/kg), PGE2 (36 g/kg), and epinephrine (36 g/kg) induced episodes of antral dysrhythmias whereas saline (1 cc) did not. The postcibal antrat motility index for the test period was not altered following saline injection, but it was reduced by 61%, 70%, and 81% following the administration of met-enkephalin, epinephrine, and PGE2, respectively (p<0.01 vs. baseline period). During periods of normal electrical rhythm, PGE2 and epinephrine significantly reduced the antral motility index (2.07±0.93 and 3.24±0.79, respectively) vs. saline (7.92±0.44) (p<0.05 for both drugs) whereas met-enkephalin (4.98±0.56) did not. In contrast, during episodes of dysrhythmia, met-enkephalin significantly depressed antral motility (1.70±0.74) (p<0.05 vs. periods with normal electrical rhythm) whereas neither epinephrine nor PGE2 caused a further reduction in antral motility from what was seen during periods of normal electrical rhythm (1.84±0.72 and 1.34±0.37, respectively). We thus conclude that intraarterial administration of met-enkephalin, PGE2, or epinephrine induce gastric dysrhythmias postcibally and depress antral contractile activity. The relaxatory effect of met-enkephalin on antral contractions is primarily due to its dysrhythmic effect whereas PGE2 and epinephrine inhibit antral motility even when the electrical rhythm is undisturbed.This work was supported in part by the USPHS, NIH grants AM26428, AM07198, and AM34988 and the Mayo Foundation.  相似文献   
986.
This is a report of the results of a placebo-controlled study in which the effects of the interaction between ethanol and marihuana on drug plasma concentrations, subjective ratings of intoxication, heart rate acceleration, and psychomotor performance were investigated. Six healthy, male, paid volunteers, moderate users of ethanol and marihuana, participated in the study. Ethanol (0.42 g/kg, 0.85 g/kg, or placebo) was administered over a 30-min interval. Fifteen minutes later the subjects smoked, in their customary manner, NIDA cigarettes containing 2.4% or 0.0004% (placebo) delta-9-tetrahydrocannabinol (THC). Each subject was tested in a single-blind, latin-square crossover design with the following six conditions: placebo ethanol/placebo marihuana; low dose ethanol/placebo marihuana; high dose ethanol/placebo marihuana; placebo ethanol/marihuana; low dose ethanol/marihuana; and high dose ethanol/marihuana. The variables measured in the study were: (a) subjective rating of ethanol and/or marihuana intoxication; (b) heart rate; (c) accuracy and latency of response in the Simulator Evaluation of Drug Impairment (SEDI) task; (d) blood ethanol concentration by gas chromatography; and (e) plasma concentration of THC by radioimmunoassay. The results indicate that the decrements due to ethanol in performance of skills necessary to drive an automobile were significantly enhanced by marihuana in an additive and perhaps synergistic manner. The administration of ethanol prior to marihuana smoking did not produce significant effects on the subjective rating of "high," heart rate acceleration, or THC plasma concentration.  相似文献   
987.
Ethanol-induced Changes in Morphology and Strength of Femurs of Rats   总被引:2,自引:0,他引:2  
Chronic ingestion of ethanol resulted in ultrastructural and mechanical changes in rat femurs. Scanning electron microscopy of the distal end of the femur revealed that the trabeculae of bones from ethanol-fed rats were thinner, more columnar, and more extensive than those from control rats. Three-point bending tests of the rat femurs showed that the maximum force or so-called "strength" required to break the bone was less in ethanol- than in control-fed animals. A significant inverse correlation was observed between the strength required to break the femur and the dose of ethanol calculated on a body weight basis. For the first time our study presents quantitative proof that a relationship exists between bone strength and the consumption of ethanol in rats. The study revealed that ethanol consumption resulted in a weaker femur compared to controls. We suggest that a common mechanism may be responsible for the decreased bone strength of ethanol-fed rats and the increased incidence of fractures in human alcoholics.  相似文献   
988.
Summary In the present study a single case observation of myoclonus during sleep-wave transition was monitored in a depressed patient treated with the monoamine oxidase inhibitor, phenelzine. The myoclonus had a rhythm of 1 c/second and lasted for two years, the duration of phenelzine treatment. Myoclonus appeared neither during wakefulness nor during sleep, but at wake-sleep-wake transitions. This switch myoclonus was associated with phasic muscle hyperactivity during REM sleep.Methysergide a 5-HT suppressor, decreased the switch myoclonus frequency and the REM muscle hyperactivity, indicating serotoninergic involvement in the mechanism of phenelzine induced myoclonus.  相似文献   
989.
Statistical issues associated with demonstrating significance between treatment groups (efficacy or superiority) and nonsignificance (equivalence) are presented and discussed. Methodologies for demonstrating efficacy of a product are proposed and contrasted, incorporating clinical and statistical criteria, with emphasis on situations in which placebo groups are precluded from the study design. Distinctions are drawn between study designs for demonstrating superiority and those for equivalence, including the determination of sample sizes needed for the different approaches. The "at least as good as" criterion is proposed as a reasonable alternative to that of equivalence in active control equivalence studies for demonstrating that dental product modifications or new products are efficacious.  相似文献   
990.
This article reports highlights from over 200 parents' observations of their preschoolers' play and verbalizations in the year following Hurricane Hugo. Commonly reported activities included reenactment and discussion of the event in multiple mediums, personification of Hugo, and expression of fears related to storms. Precocious concern for others, insight, and vocabulary were also noted. In these intact, relatively high functioning families, parents seemed able to facilitate their youngsters' adjustment without outside intervention.Portions of this report were presented in earlier form at the 1991 Society for Research in Child Development meeting in Seattle, Washington.  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