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   10678篇
  免费   512篇
  国内免费   47篇
耳鼻咽喉   123篇
儿科学   233篇
妇产科学   99篇
基础医学   1518篇
口腔科学   185篇
临床医学   612篇
内科学   2532篇
皮肤病学   94篇
神经病学   965篇
特种医学   455篇
外科学   1794篇
综合类   31篇
预防医学   287篇
眼科学   120篇
药学   862篇
中国医学   56篇
肿瘤学   1271篇
  2023年   43篇
  2022年   72篇
  2021年   157篇
  2020年   72篇
  2019年   119篇
  2018年   130篇
  2017年   134篇
  2016年   153篇
  2015年   153篇
  2014年   175篇
  2013年   272篇
  2012年   414篇
  2011年   470篇
  2010年   290篇
  2009年   260篇
  2008年   465篇
  2007年   550篇
  2006年   548篇
  2005年   562篇
  2004年   545篇
  2003年   572篇
  2002年   562篇
  2001年   348篇
  2000年   357篇
  1999年   378篇
  1998年   158篇
  1997年   152篇
  1996年   129篇
  1995年   119篇
  1994年   136篇
  1993年   128篇
  1992年   261篇
  1991年   276篇
  1990年   242篇
  1989年   227篇
  1988年   231篇
  1987年   207篇
  1986年   216篇
  1985年   168篇
  1984年   127篇
  1983年   108篇
  1982年   64篇
  1981年   62篇
  1980年   46篇
  1979年   88篇
  1978年   56篇
  1977年   33篇
  1976年   29篇
  1975年   23篇
  1974年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Twenty-two hydrocephalic patients with a ventriculoperitoneal shunt using a continuously variable flow resistance valve (Orbis-Sigma valve system; Cordis Corporation, USA) were reviewed to discuss usefulness of the shunt system. We divided the cases into two groups according to the demonstration of the cortical sulci in computed tomography (CT) as follows; A: progressive hydrocephalic cases mimicking simple brain atrophy, B: acute or subacute hydrocephalic cases with evidence of increased intracranial pressure. Patients in Group A had begun to present slowly progressive loss of activity, dementia and gait disturbance of various degrees after a long quiescent period following primary central nervous system injury. CT findings of these cases showed they were mimicking simple brain atrophy. Although the period of their deterioration was very long, ranging from 1 month to nine years, clinical signs improved in all cases after the shunt. None showed complications. Group B cases consisted of those with signs of increased intracranial pressure such as consciousness disturbance, nausea and vomiting. These cases showed poor demonstration of the cortical sulci in CT. Eleven out of thirteen cases showed satisfactory clinical improvement, though the size of the ventricle showed a slight decrease following shunt procedure. Only one case showed unilateral subdural effusion. In conclusion, this shunt system is useful for the management of ventricular enlarged cases mimicking simple brain atrophy as well as acute hydrocephalic cases. Troublesome consequences such as subdural effusion and hemorrhage rarely occur even in cases with low cerebrospinal pressure.  相似文献   
23.
Body temperature monitoring in subjects with delayed sleep phase syndrome   总被引:2,自引:0,他引:2  
To clarify the circadian aspects of delayed sleep phase syndrome (DSPS) in 4 patients with DSPS, we recorded polysomnograms and rectal temperature before and after chronotherapy. The time interval (2.7 h) between sleep onset and rectal temperature minimum before chronotherapy was shorter than the time interval after chronotherapy (5.3 h). Before chronotherapy, the period of rectal temperature rhythm was 24.7 h. After chronotherapy, the period of rectal temperature rhythm was 24.0 h. These findings lead to the conclusion that in DSPS there is a weakened mechanism of entrainment similar to that in non-24-hour sleep-wake syndrome.  相似文献   
24.
Intraperitoneal injection of free valproic acid (VPA) suppressed amygdaloid-kindled seizure 1 h after injection in rats, but had no effect at 24 h. VPA entrapped in positively charged liposomes showed a prolonged anticonvulsant effect lasting for 2 days, while the effect evaluated at 1 h was not different from that with free VPA. VPA entrapped in negatively charged liposomes exerted a significantly stronger effect at 1 h than did free VPA, while it had no significant effect at 24 h. These results suggest that surface charges on liposomes play an important role in modifying the anticonvulsant effect of VPA.  相似文献   
25.
K Abe  M Ohta 《Psychopathology》1992,25(4):218-228
Published cases of periodic psychosis of puberty and related papers were reviewed. The clinical picture is near-monthly recurrence of episodes of stupor or excitement lasting about 1 or 2 weeks, which are accompanied by delusion and in some cases also by hallucinations or confusion. This condition was found to occur more commonly in girls than in boys, and in half of the girls reported the episodes tended to start a few days before menses. Adolescents with mental retardation were more commonly affected, and this suggests that organic brain damage may play a role in the etiology in some cases. Short-term prognosis is usually favorable, but at long-term follow-up, nearly half of them were found to be suffering from affective or schizophrenic illness. The clinical importance of recognizing this psychosis early in the course of illness is emphasized.  相似文献   
26.
Evidence to suggest the presence of abnormal metabolism of oxygen free radicals in progressive muscular dystrophy is presented using an animal model. In the superficial pectoral muscles of dystrophic chickens, enzyme activities regulating the metabolism of oxygen free radicals, i.e., catalase, superoxide dismutases and glutathione peroxidase, were significantly elevated within 1 week of hatching. Activities of related enzymes, i.e., glutathione reductase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase were also elevated. In contrast, the specific activity of phosphofructokinase, the rate-limiting enzyme of the glycolytic pathway, was normal during the first 4-week period. These results suggest that there is an increased turnover of oxygen free radicals in the dystrophic muscle. This concept appears important in a further investigation of the pathogenesis and treatment of progressive muscular dystrophies.  相似文献   
27.
We reviewed the computed tomography scans of 126 term infants, ages 1-6 months; leukohypodensity was found just under the cerebral cortex (subcortical leukohypodensity [SLD]) in 3 infants (2.4%) at 1-3 months of age. On subsequent computed tomography at over 4 months of age, SLD had disappeared and anterior horn predominant dilatation of the lateral ventricles had appeared. Only 1 patient with a distinct SLD had a poor neurodevelopmental outcome: spastic diplegia. SLD in our patients is believed to be closely related to subcortical leukomalacia because of the similar location and age distribution. Transient SLD may be a mild form of cystic SLD which would require careful computed tomography follow-up examination in early infancy.  相似文献   
28.
Effects of several cytokines on des-gamma-carboxy prothrombin (PIVKA II) synthesis in human hepatoma cells were investigated to know the process of PIVKA II production during a liver allograft rejection. Human recombinant interleukin-6 (IL-6) significantly stimulated the PIVKA II synthesis without any influence on the cell proliferation. The effect was almost completely neutralized by the specific anti-IL-6 antibody. Neither tumor necrosis factor (TNF), interleukin-1 (IL-1) nor interferon-gamma (IFN-gamma) had such a stimulative effect. IL-6 appears to stimulate PIVKA II production, and would be a candidate of factors that enhance the production of PIVKA II during a liver allograft rejection.  相似文献   
29.
In order to investigate useful protective medicines for the relief of skin injury induced by irradiation, 60 methanol extracts of Chinese traditional medicines were used in the test of protective potency on skin injury. ICR male mice at 6 weeks of age were whole-body irradiated with 1100R by using a soft X-ray generator (30 kVp, 10 mA, 190 R/min). Each methanol extract of these medicines was injected intraperitoneally into mice before or after irradiation. The degrees of skin injury were determined by a score system of skin reaction within the observation period from 21st to 40th day after irradiation. Protective potency of each medicine on skin injury was calculated from the maximum mean scores of administrated group and un-administrated group. As a result of these studies, the protective potency was detected in Unsei-in, Kumibinro-to, Keisi-syakuyaku-chimo-to, Keigai-rengyo-to, Gosyuyu-to, Koso-san, Saiko-seikan-to, Syo-kankyo-to, Syo-saiko-to, Syoma-kakkon-to, Sen-kan-meimoku-to, Zokumei-to, Sokei-kakketu-to, Bokuryo-in, Mao-to and Rikkunsi-to by intraperitoneal injection before irradiation. Of these effective medicines, only Unsei-in and Mao-to are shown to have a significant protective effect by intraperitoneal injection after irradiation.  相似文献   
30.
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