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   98988篇
  免费   3913篇
  国内免费   217篇
耳鼻咽喉   1496篇
儿科学   3033篇
妇产科学   2527篇
基础医学   13418篇
口腔科学   2756篇
临床医学   5989篇
内科学   22709篇
皮肤病学   2822篇
神经病学   7703篇
特种医学   2082篇
外国民族医学   2篇
外科学   12347篇
综合类   465篇
一般理论   26篇
预防医学   11317篇
眼科学   2271篇
药学   7476篇
中国医学   324篇
肿瘤学   4355篇
  2023年   558篇
  2022年   423篇
  2021年   1706篇
  2020年   869篇
  2019年   1946篇
  2018年   3308篇
  2017年   1965篇
  2016年   1868篇
  2015年   2166篇
  2014年   2389篇
  2013年   3819篇
  2012年   6395篇
  2011年   6530篇
  2010年   3366篇
  2009年   2407篇
  2008年   5362篇
  2007年   5679篇
  2006年   5507篇
  2005年   5516篇
  2004年   5078篇
  2003年   4705篇
  2002年   4477篇
  2001年   3156篇
  2000年   3362篇
  1999年   2673篇
  1998年   466篇
  1996年   314篇
  1992年   1262篇
  1991年   1162篇
  1990年   1084篇
  1989年   965篇
  1988年   882篇
  1987年   894篇
  1986年   823篇
  1985年   788篇
  1984年   586篇
  1983年   459篇
  1979年   598篇
  1978年   345篇
  1976年   316篇
  1975年   348篇
  1974年   529篇
  1973年   490篇
  1972年   429篇
  1971年   389篇
  1970年   468篇
  1969年   425篇
  1968年   410篇
  1967年   368篇
  1966年   316篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The authors present the results of a transmission electron-microscopic study performed on a tissue sample obtained by an intraocular fine-needle aspiration biopsy in a case of retinoma. The ultrastructural study showed that the tumor was composed mainly of granular osmiophilic material which contained some tumor cells. These cells showed peculiar ultrastructural characteristics, which demonstrated their neural character, and appeared in different degenerative stages. Apparently, this is the first case in whom ultrastructural technique have been applied to study an intraocular tumor sample obtained by intraocular fine-needle aspiration biopsy, and the first case of retinoma studied by such a diagnostic approach.  相似文献   
92.
Almost 90% of primary acute pericarditis are idiopathic. Between specifics forms, a very low percentage of cases are due to chronic rheumatic diseases. A case of adult Still's disease (juvenile chronic rheumatoid arthritis) with acute pericarditis being the first clinical manifestation (besides fever and general syndrome) is presented. Therapy with oral prednisone was rapidly effective, and pericardial effusion resolved after 3 weeks of treatment, as echocardiography showed.  相似文献   
93.
We present 5 patients with cyanotic congenital heart disease in whom a pulmonary valvuloplasty was performed as palliative therapy. The patients symptoms were hypoxemic spells, very low oxygen saturation and no weight gain. The oxygenation improved and symptoms disappeared. We believe that in properly selected patients this technique represents a good therapeutic modality.  相似文献   
94.
This prospective study was carried out on thirty patients transfused with blood or blood products, by ten (33.3%) posttransfusion hepatitis was diagnosed; this is 15.75 cases per 1,000 U transfused. Four patients developed jaundice; six remained asymptomatic. In nine patients (90%) non-A, non-B hepatitis was diagnosed and one (10%) case was classified as hepatitis B. Two patients with non-A, non-B hepatitis developed chronic hepatitis, corroborated through percutaneous liver biopsy.  相似文献   
95.
The study was performed to assess the ethiological role of bile in acute pancreatitis provoked by closed duodenal loop in rat. In group I a closed duodenal loop was created by method of Nevalainen. A similar operation was performed in group II, but the common pancreatico-biliary duct was ligated just under the liver. In the control group (group C) only the mobilization of duodenum was performed. After 24 hours the mortality rate was 20% in group I, but 0% in group II and C. The amount of ascitic fluid showed significant elevation in group I versus II and group C, and in group II as compared to group C, too. The serum amylase was significantly higher in group I than group II and group C, and in group II was also higher as compared to group C. Serum total protein differed significantly between all groups, while albumin and total calcium were significantly lower in group I than group II, but group II was only slightly reduced versus group C. Histology showed no differences between groups I and II, but both differed significantly from group C. In conclusion bile seems to be an aggressive factor in pathogenesis of acute pancreatitis induced by closed duodenal loop in rat, but other factors may play more important roles.  相似文献   
96.
97.
Quantitative receptor autoradiography was used to study possible alterations of the densities of multiple serotonin (5-HT) receptor subtypes and of serotonin transporter in the brain of 5-HT(2C) receptor knockout mice. The radioligands employed were [(3)H]citalopram, [(3)H]WAY100,635, [(3)H]8-OH-DPAT, [(3)H]GR125743, [(3)H]sumatriptan, [(3)H]MDL100,907, [(125)I](+/-)DOI, [(3)H]mesulergine, [(3)H]5-HT, [(3)H]GR113808, and [(3)H]5-CT. As expected, radioligands that label 5-HT(2C) receptors showed a complete absence of labeling in mutant mice choroid plexus and significantly reduced densities in other brain regions expressing 5-HT(2C) receptors. With the rest of the radioligands, no significant alterations in the densities of labeled sites were found in any brain region. In situ hybridization showed no changes in 5-HT(2A) receptor and serotonin transporter mRNA levels, whereas 5-HT(2C) receptor mRNA levels were reduced in certain brain regions. The present results indicate that the mouse serotonergic system does not exhibit compensatory up- or down-regulation of the majority of its components (serotonin transporter and most 5-HT receptor subtypes) in response to the absence of 5-HT(2C) receptors.  相似文献   
98.
There are several indications that central nervous system (CNS) lesions in visna are immune-mediated and that cell-mediated immunity (CMI) may be of importance in the initiation of the lesions. To study the role of CMI in the pathogenesis of CNS lesions, five sheep were infected by intracerebral inoculation with visna virus and observed for 1 year. The following parameters were monitored at regular intervals: (1) neutralizing and ELISA antibodies; (2) visna virus-specific stimulation of lymphocytes from peripheral blood; (3) lymphocyte subpopulations in peripheral blood, cerebrospinal fluid (CSF) and brain at sacrifice. The CNS lesions were graded and compared with other parameters. The time course and titers of antibodies did not correlate with the severity of CNS lesions whereas the CMI did, indicating that CMI may play an important role in lesion development. The correlation of the number of CD8-positive cells in the CSF with the severity of lesions and the reversed ratio of CD4/CD8-positive cells in the diffusely infiltrated neuroparenchyma indicates that the CD8-positive T lymphocyte may be an important effector cell in the induction of CNS lesions.  相似文献   
99.
Subchronic administration of cocaine induces behavioral sensitization (increasing hypermotility) to a challenge dose of the drug administered 72 h after the cessation of treatment. The effects of repeated administration of the neurohypophyseal hormones oxytocin (OXT) and arginine8-vasopressin (AVP) on the development of behavioral sensitization induced by subchronic treatment with cocaine were investigated in mice. Repeated treatment of OXT and AVP did not modify the locomotor stimulatory effect of the challenge dose of cocaine in cocaine-naive control animals. OXT in a dose of 0.5 microgram (sc) augmented the cocaine-induced behavioral sensitization. In contrast, AVP (0.005-0.5 microgram/mouse, sc) dose dependently attenuated the development of sensitization to the hypermotility-inducing effect of cocaine. The results suggest that the behavioral sensitization induced by cocaine can be modulated in opposite directions by neurohypophyseal hormones.  相似文献   
100.
The authors' aim was to evaluate the range of uroflowmetry in diagnostics of stress urinary incontinence (sui) in women. The examinations were carried out in 59 women with sui, aged from 35 to 45 years (group I). The control group consisted of 20 asymptomatic women (group II). To evaluate volumes of urine voided during micturition in a unit of time a urological flowmeter UF-1 (produced by COTM, Bia?ystok) was used. Numeric data of flow were analysed, as well as registered curves of flow were ascribed to one of the following flow patterns: normal, multi-peak or interrupted. The conducted studies revealed statistically significant differences in flow values in group I, compared to group II. A more frequent incidence of multi-peak and interrupted flow patterns was found in women with sui, which could be related to a neurogenic component in etiology of the disease.  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