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   2919367篇
  免费   220392篇
  国内免费   5595篇
耳鼻咽喉   39216篇
儿科学   95967篇
妇产科学   80605篇
基础医学   413938篇
口腔科学   86604篇
临床医学   262313篇
内科学   564501篇
皮肤病学   64221篇
神经病学   232051篇
特种医学   113773篇
外国民族医学   701篇
外科学   442190篇
综合类   70473篇
现状与发展   6篇
一般理论   1036篇
预防医学   223145篇
眼科学   69185篇
药学   216889篇
  9篇
中国医学   6400篇
肿瘤学   162131篇
  2018年   30949篇
  2017年   23873篇
  2016年   26371篇
  2015年   30204篇
  2014年   41947篇
  2013年   62576篇
  2012年   85984篇
  2011年   90670篇
  2010年   53698篇
  2009年   50447篇
  2008年   85348篇
  2007年   90391篇
  2006年   91239篇
  2005年   87964篇
  2004年   85735篇
  2003年   81926篇
  2002年   79452篇
  2001年   141178篇
  2000年   145189篇
  1999年   121652篇
  1998年   33229篇
  1997年   29562篇
  1996年   29458篇
  1995年   28439篇
  1994年   26428篇
  1993年   24583篇
  1992年   96288篇
  1991年   93514篇
  1990年   90646篇
  1989年   87490篇
  1988年   80585篇
  1987年   79015篇
  1986年   75087篇
  1985年   72063篇
  1984年   53481篇
  1983年   45943篇
  1982年   26570篇
  1981年   23789篇
  1979年   49520篇
  1978年   34192篇
  1977年   29073篇
  1976年   27281篇
  1975年   28887篇
  1974年   35217篇
  1973年   33824篇
  1972年   31237篇
  1971年   29287篇
  1970年   27077篇
  1969年   25368篇
  1968年   23364篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A quasi-experimental study was conducted to evaluate the effect of preoperative interviews on patients' anxiety levels. A convenience sample of 60 was assigned between two groups of equal size: a treatment group in which subjects were interviewed by a perioperative nurse or a control group in which subjects were not interviewed. All subjects completed state-trait Anxiety Inventory questionnaires. Group comparison using analysis of covariance showed subjects who were interviewed by the perioperative nurse reported significantly less anxiety than control group subjects.  相似文献   
992.
Handcuff neuropathies   总被引:1,自引:0,他引:1  
D A Stone  R Laureno 《Neurology》1991,41(1):145-147
Compressive neuropathy due to tight application of handcuffs occurred in 5 patients. The superficial radial nerve was affected in 8 hands and the median nerve in two. Neurologic deficits persisted as long as 3 years after handcuffing. Nerve conduction studies helped to exclude malingering and other diagnoses. All patients had been intoxicated when handcuffed or had been arrested with force. The handcuff mechanism, which allows accidental overtightening after application, is an unrecognized factor in these neuropathies.  相似文献   
993.
Biodegradable controlled-release microsphere systems made with the biocompatible biodegradable polyester excipient poly [DL lactide-co-glycolide] constitute an exciting new technology for drug delivery to the central nervous system (CNS). The present study describes functional observations indicating that implantation of dopamine (DA) microspheres encapsulated within two different polymer excipients into denervated-striatal tissue assures a prolonged release of the transmitter in vivo. Moreover, in this regard, the results show that there were clear cut temporal differences in the effect of the two DA microsphere formulations compared in this study, probably reflecting variations in the actual composition (i.e., lactide to glycolide ratio) of the two copolymer excipients examined. This technology has considerable potential for basic research with possible clinical application.  相似文献   
994.
A quantitative assay for ALZ-50 immunoreactivity was evaluated in samples of superior temporal gyrus taken at autopsy from 13 Alzheimer patients and 11 controls. The assayable immunoreactivity appears to be stable for at least 24 hours postmortem but was lost with formalin fixation. The mean value of the Alzheimer patients was tenfold higher than that of the controls (P less than .002). The values of four Alzheimer samples overlapped with the low levels seen in controls, but no controls had elevated levels. In this sample population, therefore, the assay had a sensitivity of 69% and specificity of 100%.  相似文献   
995.
The head circumferences of 64 patients with Duchenne muscular dystrophy were measured and found to be greater than those of a normal population. The patients had relative, and in 12 cases, absolute macrocephaly. 47 of the 64 patients underwent intelligence testing and were found to be significantly intellectually impaired, particularly in verbal and language skills. There was no correlation between head circumference or absolute macrocephaly and intellectual performance. The cause of macrocephaly in these patients is unknown and its relevance to the aetiology of intellectual impairment in Duchenne muscular dystrophy is not yet clear.  相似文献   
996.
997.
Central axons of sensory ganglion (SG) neurons of the Xenopus tail enter the spinal cord via the ventral roots and travel dorsally and rostrally following a diagonal course within the lateral marginal zone (LMZ) to reach the dorsolateral fasciculus (DLF) (Nordlander et al.: Brain Res., 440:391-395, 1988). Axons are dispersed as they cross the cord. At the DLF they turn and travel together rostrally, sharing the fascicle with axons of primary sensory neurons (Rohon-Beard cells) already present in the tract. In this paper we analyze the growth patterns of the central projections of SG axons in the tail by using HRP applied to proximal branches of tail spinal nerves. Growth cones of the diagonal route are variable in configuration, often bearing processes that spread within the LMZ. Once the DLF, growth cones change shape, becoming distinctly linear. While growth cones navigating the diagonal part of the route never contact or fasciculate with other diagonal SG axons, SG growth cones and axons of the DLF are more closely associated with their fellows. Measurements of the slopes of SG axons in the diagonal route indicated a limited range with a mean of 23 degrees with respect to the cord axis. On the basis of these observations, we conclude that 1) navigational patterns for growth cones of this pathway differ for the diagonal versus the DLF part of its course, and 2) fasciculation is not a mechanism used by SG axons to reach the DLF, but that instead, each axon is able to find its way independently.  相似文献   
998.
Sera of successive littermates of mothers producing anti-allotype antibodies (Ab) were analysed for altered a locus or b locus allotype expression. We measured the allotype concentration in sera of 66 individuals (17 litters) of seven mothers producing anti-a1 Ab, and 63 individuals (15 litters) of seven mothers producing anti-b4 Ab, in an enzyme-linked immunosorbent assay (ELISA). We confirmed that the ability to induce allotype suppression in utero increases with the number of antigen boosts applied to the mother, even though the Ab titre in the maternal serum may be decreased. All individuals of a litter expressed the allotype in about equal concentration. This contrasts the results we obtained when newborn rabbits were injected with anti-allotype antiserum. Injection of the same amount of anti-allotype antiserum into nine offspring of two mothers caused allotype suppression in only five individuals, showing no effect in the others. No suppression was observed when IgG-depleted antiserum was injected into newborn rabbits. As expected, maternal antibodies to a paternal allotype do not affect the Mendelian distribution of the progeny phenotypes.  相似文献   
999.
A case of an ameloblastoma diagnosed about 3 1/2 years after removal of an impacted mandibular 3rd molar is presented. The pre-operative radiographs, though poor in quality, showed an ill-defined radiolucency in relation to the tooth. This feature was not apparent to the examiners at the time of first presentation. Despite unfavourable working conditions in developing countries, a high level of suspicion should be maintained to avoid serious sequelae at a later stage.  相似文献   
1000.
One hundred and sixty-five Cerinate porcelain veneers were placed by 11 private practice clinicians from diverse locations throughout the USA. The veneers were evaluated over a 3-year service period using Kodachrome photographs and grading of clinical characteristics by evaluators. The following factors were evaluated: (1) esthetics; (2) margin fit; (3) margin discoloration; (4) breakage; (5) gingival irritation; (6) patient acceptance; and (7) caries. Specific characteristics and their evaluations over three years were: (1) Esthetics started out excellent and remained that way; (2) Margin fit was acceptable at the beginning of the study and was actually perceived to improve, perhaps related to cement at the margins wearing and smoothing; (3) Margin discoloration started very low and became slightly worse; (4) Breakage was present during each of the 3 years, and 13 percent of veneers had some breakage after 3 years. Changes in clinical procedures are suggested in this paper to diminish this problem; (5) Gingival irritation was minimal throughout the study; (6) Patient acceptance was excellent at the beginning of the study and improved; and (7) Dental caries involvement was minimal, with only one veneered tooth showing caries involvement. Over the 3-year period, the veneers provided excellent service overall.  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