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   700768篇
  免费   28506篇
  国内免费   496篇
耳鼻咽喉   7782篇
儿科学   23360篇
妇产科学   15456篇
基础医学   108534篇
口腔科学   13843篇
临床医学   60513篇
内科学   125306篇
皮肤病学   12510篇
神经病学   50122篇
特种医学   28495篇
外国民族医学   53篇
外科学   106161篇
综合类   9893篇
现状与发展   2篇
一般理论   107篇
预防医学   56163篇
眼科学   14619篇
药学   50610篇
  1篇
中国医学   1749篇
肿瘤学   44491篇
  2021年   3909篇
  2018年   27135篇
  2017年   21020篇
  2016年   23940篇
  2015年   6222篇
  2014年   7859篇
  2013年   11209篇
  2012年   22296篇
  2011年   37873篇
  2010年   28263篇
  2009年   20057篇
  2008年   34731篇
  2007年   38603篇
  2006年   17392篇
  2005年   18315篇
  2004年   19121篇
  2003年   19452篇
  2002年   17180篇
  2001年   22687篇
  2000年   23368篇
  1999年   19067篇
  1998年   5422篇
  1997年   4559篇
  1996年   4475篇
  1995年   4216篇
  1992年   14453篇
  1991年   15912篇
  1990年   16077篇
  1989年   15711篇
  1988年   14366篇
  1987年   14243篇
  1986年   13198篇
  1985年   12726篇
  1984年   9418篇
  1983年   8021篇
  1982年   4209篇
  1979年   8947篇
  1978年   6400篇
  1977年   5155篇
  1976年   5513篇
  1975年   6621篇
  1974年   7442篇
  1973年   7162篇
  1972年   6605篇
  1971年   6316篇
  1970年   5907篇
  1969年   5490篇
  1968年   5177篇
  1967年   4625篇
  1966年   3967篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
BACKGROUND: One previous follow-up study suggested that inpatient bulimic women do quite poorly; after an interval of 2 to 5 years, only 13% were recovered. To examine the course and outcome of a sample of patients with bulimia nervosa that was severe enough to require inpatient hospitalization, the authors conducted the following study. METHOD: Women (N = 52) with DSM-III-R bulimia nervosa were sought 2 to 9 years after hospitalization. Prior to contact, a retrospective chart review was conducted to determine global functioning and admission diagnoses. At follow-up, patients participated in a 4 to 6 hour interview that assessed current and lifetime Axis I disorders (SCID-I), current Axis II disorders (PDE), eating behaviors (EAT, BSQ, EDI, PSR), global functioning (GAF), social adjustment (SAS-SR), and treatment and medical problems experienced since discharge. To assess the significance of differences between the recovered and the currently bulimic women, Yates-corrected chi-square tests and two-tailed t tests were used. RESULTS: Of the 52 women, 46 were interviewed, 1 had died, and 5 could not be located. Of the 46 interviewed women, 39% had fully recovered, 20% had partially recovered, and 41% were currently bulimic. The likelihood of recovery increased with length of time since discharge. While medical problems related to the bulimia were few, treatment with phenelzine was associated with three reports of serious hypertensive episodes, one of which led to death. Global functioning before hospitalization, lifetime DSM-III-R Axis I diagnoses, and current Axis II diagnoses were not associated with outcome. CONCLUSIONS: These findings suggest that even severely ill bulimic patients have a significant chance of achieving full recovery.  相似文献   
103.
BACKGROUND AND PURPOSE: The familial occurrence of intracranial aneurysms and cervical artery dissections has been described in different families and supports the hypothesis that a primary arteriopathy may play a role in the pathogenesis of these disorders. Although the basis for this arteriopathy is generally not believed to be similar among cases of intracranial aneurysms and cervical artery dissections, several similarities exist in the epidemiology of these disorders and a common underlying arterial abnormality may be suspected. SUMMARY OF REPORTS: The medical records of all 175 patients with spontaneous dissections of the cervical arteries who were seen at the Mayo Clinic between 1970 and 1989 were reviewed to identify families in which intracranial aneurysms and cervical dissections coexisted. Three families were identified in which intracranial aneurysms and cervical artery dissections were observed among siblings. These families are described in detail. CONCLUSIONS: The familial occurrence of intracranial aneurysms and cervical artery dissections within the same families provides support to the importance of a common underlying arteriopathy in the pathogenesis of both these disorders. The underlying vascular defect may, at least in some cases, be inherited.  相似文献   
104.
105.
106.
107.
The effects of different amounts of dietary zinc on the Zn absorption rate and on Zn, calcium and magnesium concentrations in tissues of MOPC 104E tumor-bearing Balb/c mice were determined. The Zn absorption rate was inversely related to the amounts of Zn in their diets and was lower than that of nontumor-bearing control mice fed a laboratory mice chow. Zn concentrations of tumor-bearing mice were also low compared with control mice but tumor Zn concentrations, regardless of the concentrations of Zn in the diets, were higher than those of normal tissues of the host other than the pancreas. Ca concentrations in tumor and tissues of tumor-bearing mice were higher than in control animals but Mg concentrations in tissues of tumor-bearing mice appeared to be similar to those of control mice. Results suggest that tumor-bearing mice have a lower intestinal Zn absorption capacity and a higher Zn uptake rate causing other tissues to become hypozincemic and hypercalcemic.  相似文献   
108.
109.
We introduce the concept of the metabolic centroid spectrum as the feature space to characterize the distribution of metabolic activity in three-dimensional brains. The method computes the metabolic centroid of a brain subvolume for each increment of metabolic activity occurring in the whole brain. The result is the metabolic spectral signature, a continuous three-dimensional curve whose shape reflects the distribution of metabolic rates in the brain. The method's sensitivity to metabolic distribution asymmetries is greatly increased over that of the metabolic centroid method, while retaining its advantages; it is almost invariant to head size, head positioning, photon scatter, and the positron emission tomography (PET) camera's full width at half-maximum. It does not require magnetic resonance, computed tomography, or x-ray images. To test the method we analyzed the metabolic PET images of 40 normal subjects and 20 schizophrenics. The results show a unification of several metabolic characteristics of schizophrenic brains, such as laterality, hypofrontality, cortical/subcortical abnormalities, and overall brain hypometabolism, which were identified by different laboratories in separate studies using differing methodologies. Here they are presented by a single automatic objective method.  相似文献   
110.
Gamma-aminobutyric acid (GABA) in the thalamus has mainly been associated with the inhibitory modulation of the sensory and cortical flow of information via a 'classical', chloride-dependent, GABAA receptor-mediated action. However, the discovery of a late, long-lasting potassium-dependent inhibitory postsynaptic potential (IPSP) mediated by GABAB receptors present on thalamocortical cells, has allowed new insights into our understanding of the physiological role of this neurotransmitter. In particular, work on the dorsal lateral geniculate nucleus indicates that together with a relatively weak inhibition, GABAB receptor-mediated IPSPs 'prepare' thalamocortical cells for burst firing by activating low-threshold calcium potentials. Thus, GABA in the thalamus can no longer be viewed only as a 'classical' inhibitory transmitter but also as a neuromodulator with a 'priming' role for burst firing excitation. This dual role of GABAB receptors in inhibition and excitation of thalamocortical cells might allow different interpretations of earlier findings in animals and humans, both in healthy and pathological conditions. It will also help to identify new functions for postsynaptic GABAB receptors in other parts of the central nervous system.  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