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   22162篇
  免费   2089篇
  国内免费   53篇
耳鼻咽喉   195篇
儿科学   848篇
妇产科学   496篇
基础医学   2883篇
口腔科学   452篇
临床医学   2480篇
内科学   4547篇
皮肤病学   168篇
神经病学   2120篇
特种医学   789篇
外科学   3105篇
综合类   392篇
一般理论   12篇
预防医学   2439篇
眼科学   459篇
药学   1522篇
中国医学   27篇
肿瘤学   1370篇
  2022年   141篇
  2021年   342篇
  2020年   202篇
  2019年   396篇
  2018年   391篇
  2017年   262篇
  2016年   321篇
  2015年   340篇
  2014年   577篇
  2013年   873篇
  2012年   1208篇
  2011年   1223篇
  2010年   680篇
  2009年   609篇
  2008年   1129篇
  2007年   1228篇
  2006年   1143篇
  2005年   1118篇
  2004年   1093篇
  2003年   1066篇
  2002年   1065篇
  2001年   489篇
  2000年   515篇
  1999年   451篇
  1998年   275篇
  1997年   228篇
  1996年   237篇
  1995年   234篇
  1994年   230篇
  1993年   224篇
  1992年   372篇
  1991年   304篇
  1990年   334篇
  1989年   345篇
  1988年   276篇
  1987年   288篇
  1986年   311篇
  1985年   277篇
  1984年   254篇
  1983年   240篇
  1982年   185篇
  1981年   197篇
  1980年   156篇
  1979年   217篇
  1978年   185篇
  1977年   127篇
  1976年   152篇
  1975年   142篇
  1974年   148篇
  1973年   146篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
981.
Pre-natal ventriculomegaly and hydrocephalus   总被引:2,自引:0,他引:2  
Ultrasonic imaging of the human fetal brain has allowed ventriculomegaly and hydrocephalus to be categorized. In this study 40 fetuses with ventriculomegaly and 21 with an Arnold-Chiari malformation and a myelomeningocele had ventriculomegaly that resolved, stabilised or progressed in utero. Within the progressive group were those with hydrocephalus, hydrocephalus being defined as expansion of the cerebral ventricular atria together with disproportionate increase in the head circumference. The prognosis for fetuses with resolving and stable ventriculomegaly was good, reflecting the fact that the ventricular dilatation in these cases was probably caused by delayed parenchymal and cerebrospinal fluid pathway development. Whereas the prognosis for progressive ventriculomegaly was generally poor, suggesting that the causes were likely to have been chromosomal, genetic, an infective agent or a catastrophic event which had an adverse effect on parenchymal development. The causes of hydrocephalus also adversely affected brain development but additional damage was caused by raised intracranial pressure.  相似文献   
982.
983.
984.
Interjudge reliability for videofluoroscopic (VFS) swallowing evaluations has been investigated, and results have, for the most part, indicated that reliability is poor. While previous studies are well-designed investigations of interjudge reliability, few reports of intrajudge reliability are available for VFS measures derived from frame-by-frame analysis that clinicians typically employ. The purpose of this study was to examine the inter- and intrajudge reliability of VFS examination measures commonly used to assess swallowing functions. No training to criteria occurred. VFS examinations were conducted on 20 patients who had suffered a stroke within six weeks and had no structural abnormalities or tracheostomies. Three clinical judges served as subjects and rated the VFS examinations from videotape using frame-by-frame analysis. A clinician's repeated review of measures employed in the 20 examinations indicated high intrajudge reliability for a number of measures, suggesting that an experienced clinician may employ consistent standards for rating certain VFS measures across patients and time. These standards appear to vary among clinicians and yield unacceptable interjudge reliability. The need to train clinicians to criteria to improve interjudge reliability is discussed.  相似文献   
985.
Xu X  Russell T  Bazner J  Hamilton J 《Brain research》2001,889(1-2):274-277
The present study investigated the amnestic effects of N-methyl-D-aspartate (NMDA) receptor antagonist AP5 and nitric oxide (NO) synthase inhibitor 7-NI in avoidance conditioning in goldfish. The results showed that both AP5 and 7-NI, without impairing performance processes, produced anterograde amnesia when given before training. Furthermore, 7-NI produced retrograde amnesia when given immediately following training while AP5 did not. Thus, AP5 and 7-NI affected different phases of learning and memory.  相似文献   
986.
987.
Our changing health care environment presents new challenges to the surgical profession. This article examines those concerns, including strains on surgeons' professional values, financial pressures resulting from federal laws and regulations, the expansion of managed care, and demands for improved continuing education opportunities. This article illustrates how the American College of Surgeons has been helping surgeons cope with the shifts in balance taking place around them. It further highlights how the American College of Surgeons is moving forward in all areas of concern to surgeons by promoting standards for surgical care, educating third-party payors about the effects of financial constraints, expanding its educational programs, and seeking innovative methods to fulfill its mission.  相似文献   
988.
989.
Previous studies have shown a significant reduction of prepulse inhibition of startle in boys with primary nocturnal enuresis. Those enuretic boys who had higher IQs showed less prepulse inhibition. This study evaluates the association of prepulse inhibition and IQ in primary nocturnal enuresis in respect to family history of primary nocturnal enuresis. Prepulse inhibition of startle was studied in 83 boys with primary nocturnal enuresis and 57 non-enuretic boys using an interval of 120 ms between the onset of a 75 dB 1000 Hz tone and a 104 dB noise burst. Of the boys with primary nocturnal enuresis, 56 had a family history of primary nocturnal enuresis and 27 had no family history (no first-degree relative). Of the 57 non-enuretic boys, 42 also had no family history (no first-degree relative) of primary nocturnal enuresis, while 15 did have a positive family history. Associations between prepulse inhibition and IQ scores were compared among these four groups. Strong and significant associations between prepulse inhibition deficit and higher IQ scores in the enuretic group with familial primary nocturnal enuresis were unique in comparison to the other groups. Conclusions: The strong heritabilities of primary nocturnal enuresis, intelligence and prepulse inhibition suggest genetic mediation of the association of prepulse inhibition with intelligence in familial primary nocturnal enuresis.  相似文献   
990.
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