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   2159367篇
  免费   154150篇
  国内免费   2837篇
耳鼻咽喉   29505篇
儿科学   70368篇
妇产科学   59057篇
基础医学   314887篇
口腔科学   60368篇
临床医学   197348篇
内科学   414210篇
皮肤病学   47891篇
神经病学   169077篇
特种医学   82230篇
外国民族医学   461篇
外科学   315804篇
综合类   44630篇
现状与发展   3篇
一般理论   781篇
预防医学   167104篇
眼科学   49336篇
药学   165370篇
  11篇
中国医学   4525篇
肿瘤学   123388篇
  2018年   22617篇
  2017年   17509篇
  2016年   19490篇
  2015年   22155篇
  2014年   30631篇
  2013年   45944篇
  2012年   62691篇
  2011年   66572篇
  2010年   38978篇
  2009年   37138篇
  2008年   62584篇
  2007年   66951篇
  2006年   67219篇
  2005年   64971篇
  2004年   62333篇
  2003年   59912篇
  2002年   57921篇
  2001年   104420篇
  2000年   106838篇
  1999年   89666篇
  1998年   23945篇
  1997年   21465篇
  1996年   21657篇
  1995年   20352篇
  1994年   18845篇
  1993年   17701篇
  1992年   69537篇
  1991年   67585篇
  1990年   66036篇
  1989年   63843篇
  1988年   58459篇
  1987年   57044篇
  1986年   54199篇
  1985年   51053篇
  1984年   38057篇
  1983年   32748篇
  1982年   18784篇
  1981年   16725篇
  1979年   35318篇
  1978年   24969篇
  1977年   21554篇
  1976年   19450篇
  1975年   21437篇
  1974年   25623篇
  1973年   25011篇
  1972年   23820篇
  1971年   22298篇
  1970年   20826篇
  1969年   19869篇
  1968年   18170篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
991.
We developed a novel method which enables bloodless exposure of the levator veli palatini muscle in rat in order to investigate the physiological properties of this muscle. The levator veli palatini muscle which is innervated by a branch of the glossopharyngeal nerve showed rhythmic spontaneous movement in rats. Cutting the branch supplying LVP of the glossopharyngeal nerve caused cessation of the spontaneous movement of the levator veli palatini muscle. The spontaneous discharges of the glossopharyngeal nerve were synchronized with those of the phrenic nerve. A mixture of 95% oxygen and 5% room air influenced the efferent discharges from the branch of the glossopharyngeal nerve supplying the levator veli palatini muscle. These findings indicate that the motor nerve supply to the levator veli palatini muscle is the glossopharyngeal nerve, and the levator veli palatini muscle is related to the respiratory system, in particular with inspiration in rats.  相似文献   
992.
X chromosome instability associated with familial Turner syndrome   总被引:1,自引:0,他引:1  
A family with two members (two generations) exhibiting Turner syndrome is described. Cytogenetic studies on these individuals showed the presence of multiple X chromosome changes. Evidence is presented to show that the maternally inherited X chromosome is the chromosome involved in the structural alterations observed. The effect of a tendency of the maternal X chromosome to break at specific sites on the development of the Turner phenotype and abnormal karyology is discussed.  相似文献   
993.
Receptionists, appointment systems and continuity of care.   总被引:5,自引:4,他引:1       下载免费PDF全文
The influence of receptionists on continuity of care in four group practices was examined. Twenty two receptionists were observed making 543 appointments and afterwards were interviewed about their personal priority for continuity of care. One of the practices ran a personal list system. It was found that the personal list practice attracted more requests for a specific doctor and time which were then more difficult to satisfy. Most receptionists thought it was important that patients should see the same doctor but their influence seemed to be small compared with that of the doctor as expressed in practice policies. Marked variation in demand for individual doctors was seen in two of the practices without a personal list system.  相似文献   
994.
B R Wang  E Senba  M Tohyama 《Neuroscience》1989,28(3):711-723
Studies were made on whether substance P-, leucine-enkephalin- and 5-hydroxytryptamine (serotonin)-like immunoreactive fibers exert a direct influence on the cremaster motoneurons of the male rat by immunocytochemistry combined with retrograde tracing at the light- and electron-microscopic levels. Horseradish peroxidase was used as a retrograde tracer. Two days after injection of horseradish peroxidase into the genitofemoral nerves, its accumulation in the cremaster motoneurons was demonstrated by the diaminobenzidine-nickel method. On immunocytochemical examination of the same sections immunoreactive end-products were detected by the peroxidase-antiperoxidase method. Two different kinds of reaction products were distinguishable at both the light- and electron-microscopical levels. The horseradish peroxidase-labeled cremaster motoneurons at the L1 and L2 levels of the spinal cord were surrounded by abundant immunoreactive terminals. Examination at the ultrastructural level showed that substance P-like immunoreactive terminals formed synaptic contacts almost exclusively with the proximal dendrites of these horseradish peroxidase-labeled cremaster motoneurons. On the other hand, in the leucine-enkephalin- and serotonin-like boutons, significant numbers of axosomatic contacts with horseradish peroxidase-labeled cells were seen although axodendritic contacts with horseradish peroxidase-labeled cells were predominant. Occasionally, leucine-enkephalin-like immunoreactive fibers with synapses on horseradish peroxidase-labeled neurons formed axoaxonic contacts with other leucine-enkephalin-like axonal terminals. Thus, substance P-, leucine-enkephalin- and serotonin-like fibers clearly regulate the function of cremaster motoneurons monosynaptically. The varied synaptic contacts of these fibers according to the neuroactive substances involved suggest different actions of these substances on the cremaster motoneurons.  相似文献   
995.
This study investigated analogical reasoning abilities of alcoholics who had been abstinent from alcohol for at least 1 year. Their performance was compared to that of nonalcoholic controls matched as a group for education, age, and gender. Solution times and error rates were modeled using a regression model. Results showed a nonsignificant trend for alcoholics to be faster, but more error prone, than controls. The same componential model applied to both groups, and fit them equally well. Although differences have been found in analogical reasoning ability between controls and alcoholics immediately following detoxification, we find no evidence of differences after extended periods of sobriety.  相似文献   
996.
The aqueous, organic, and volatile oil extracts of leaves of Eugenia uniflora Linn. Family Myrtaceae were investigated for antibacterial properties using agar dilution techniques. The aqueous extract was the most active against the organisms compared to the organic and volatile oil extracts. The extracts were found to inhibit Gram positive Staphylococcus aureus and Bacillus subtilis and Gram negative Escherichia coli and Shigella dysentcriae. Pseudomonas aeruginosa, Klebsiella pneumoniac, and Salmonella typhi were not inhibited.  相似文献   
997.
A retrospective analysis of the results of 27,801 cervical smears from one year in a community laboratory was undertaken. This represented 23,820 individual patients. Abnormalities were seen in 9.3% of patients. Three point seven percent of patients had benign abnormalities, 5.5% had cervical intraepithelial neoplasia and 0.1% had major abnormalities. The incidence of cervical epithelial abnormality was highest in the 15-34 age group but major abnormalities were seen most often in the 55+ age group. Human papillomavirus was more commonly seen in the youngest age group. The presence of inflammation was reported in 65% of the smears. Thirty percent of smears had no endocervical cells and 0.6% were grossly inadequate. Fifteen percent of patients had repeat smears and 3% of total smears were judged unnecessary. Forty two point six percent of patients less than 55 years of age in the laboratory population base had a smear but only 7.9% of those over 55.  相似文献   
998.
Four tricyclic antidepressants, amitriptyline, imipramine, desipramine and iprindole have been shown to partially protect mouse brain monoamine oxidase in-vivo from the irreversible enzyme inhibition produced by subsequent injection of phenelzine. Levels of protection were similar when the enzyme was assayed with selective substrates (5-hydroxytryptamine and phenethylamine) for both the A and B forms of the enzyme. Although other explanations cannot at this stage be ruled out, these observations are consistent with the tricyclic antidepressants acting as reversible inhibitors of brain monoamine oxidase in-vivo.  相似文献   
999.
Addison's disease is rarely caused by metastatic cancer. We report a unique case of hypoadrenalism owing to metastatic transitional cell carcinoma of the bladder. The relevant literature is reviewed.  相似文献   
1000.
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