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   900604篇
  免费   62518篇
  国内免费   2341篇
耳鼻咽喉   12495篇
儿科学   28714篇
妇产科学   26254篇
基础医学   126712篇
口腔科学   24737篇
临床医学   74842篇
内科学   183339篇
皮肤病学   19008篇
神经病学   71466篇
特种医学   36459篇
外国民族医学   336篇
外科学   142207篇
综合类   19040篇
一般理论   247篇
预防医学   64640篇
眼科学   20131篇
药学   63857篇
中国医学   1798篇
肿瘤学   49181篇
  2018年   9113篇
  2017年   7199篇
  2016年   7707篇
  2015年   8760篇
  2014年   12397篇
  2013年   19284篇
  2012年   25737篇
  2011年   27323篇
  2010年   16632篇
  2009年   15819篇
  2008年   26192篇
  2007年   27795篇
  2006年   27976篇
  2005年   27482篇
  2004年   26325篇
  2003年   25489篇
  2002年   25079篇
  2001年   41363篇
  2000年   42562篇
  1999年   36272篇
  1998年   9973篇
  1997年   9152篇
  1996年   9085篇
  1995年   8447篇
  1994年   8084篇
  1993年   7586篇
  1992年   28202篇
  1991年   26982篇
  1990年   26415篇
  1989年   25348篇
  1988年   23554篇
  1987年   23172篇
  1986年   22251篇
  1985年   21152篇
  1984年   15806篇
  1983年   13479篇
  1982年   8088篇
  1979年   14592篇
  1978年   10208篇
  1977年   8628篇
  1976年   8147篇
  1975年   8960篇
  1974年   10699篇
  1973年   10183篇
  1972年   9661篇
  1971年   8918篇
  1970年   8584篇
  1969年   8026篇
  1968年   7684篇
  1967年   7086篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Personality of patients with pseudoseizures   总被引:7,自引:0,他引:7  
We studied personality features of 19 patients with pseudoseizures (PS) only. Scores on a personality inventory (MMPI) were compared with those of adults with generalized seizures and correlated to cognitive measures (Halstead-Reitan). Mean MMPI scores did not differ significantly, and no profile distinguished PS and epilepsy patients. MMPI abnormalities of PS patients were diverse and seldom characteristic of hysteria. Eight PS patients had cognitive impairment, two without MMPI evidence of personality disorder. These findings suggest that the etiology of pseudoseizures is multifactorial, involving different psychopathologies and sometimes cerebral dysfunction.  相似文献   
942.
Abnormal pressor responses are known to occur in the maternal circulation in pregnancy-induced hypertension (PIH), but little is know of the response of the foetal circulation. The responsiveness of umbilical arteries in PIH can be studied after delivery, and this is a useful model to explore the pathophysiological mechanisms involved. In the present experiments, the in vitro response of umbilical artery rings to bradykinin and 5-hydroxytryptamine (5-HT) was tested and ultrastructural changes investigated. Umbilical arteries from 48 cords were studied. Fifteen of the mothers had PIH, five had essential hypertension pre-dating the pregnancy and five had diabetes. Twenty-three women had pregnancies uncomplicated by hypertension or serious medical or obstetric problems and these served as controls. Umbilical arteries from the severe proteinuric PIH group were significantly more responsive to 5-HT as assessed by affinity constants (P less than 0.05). The responsiveness of arteries from all other groups did not differ from the normal cases. A probable mechanism for the findings is endothelial damage as a result of pre-eclamptic disease. This was substantiated by ultrastructural evidence.  相似文献   
943.
Tests of orientation, concentration and shortterm visual memorywere used to assess 72 patients 1 day before, and 2 days after,elective major surgery. Patients were premedicated with papaveretumand either atropine or glycopyrrolate, before receiving a standardgeneral anaesthetic. Those who had received atropine showedsignificant postoperative short-term memory deficit (P< 0.01),but no change in orientation or concentration. Those who hadbeen given glycopyrrolate showed no significant cognitive changesafter surgery. As glycopyrrolate does not cross the blood-brainbarrier freely, these findings support the involvement of centralcholinergic mechanisms in the deterioration of cognitive functionin the postoperative period.  相似文献   
944.
A 14-year-old junior high school boy was admitted to our institute. Previously he had been diagnosed as having peripheral pulmonary stenosis (Gay's classification, type IV) at the age of 2 years and 10 months. On this occasion, however, a diagnosis of supravalvular aortic stenosis was made, with a pressure gradient of about 120 mmHg, and all examinations showed spontaneous remission of peripheral pulmonary stenosis. He underwent a successful standard aortoplasty. This is the first reported case of spontaneous remission of peripheral pulmonary stenosis.  相似文献   
945.
Cystatin C, alias post-gamma-globulin or gamma-trace protein, has been shown to be a potent inhibitor of cysteine proteinases; this protein is normally present in different biological fluids, but particularly so in cerebrospinal fluid. The concentration of cystatin C was determined by radial immunodiffusion in cerebrospinal fluid from patients affected with multiple sclerosis, patients affected with various neurological diseases and in controls; it was also determined in brain tissue from 2 patients affected with multiple sclerosis and 3 control brains. Cystatin C cerebrospinal fluid levels were undetectable or depressed in many multiple sclerosis cases and the median value differed significantly from the control one. Its low concentration in multiple sclerosis suggests that the regulation of cysteine proteinases is impaired in this disease; hence enhanced activity of cysteine proteinases could initiate, or increase the breakdown of myelin. Although it is perhaps a little premature to consider cystatin C as a marker for multiple sclerosis, this protein is nevertheless associated to demyelination; consequently its biochemical assay in cerebrospinal fluid is recommended as a complementary diagnostic tool.  相似文献   
946.
Unilateral pseudobulbar syndrome with limited capsulothalamic infarction   总被引:5,自引:0,他引:5  
A unilateral pseudobulbar syndrome consequent to unilateral capsulothalamic infarction is described. Motor deficit of the face was associated with marked velar and pharyngeal unilateral palsy; paresis of limbs was mild. ACT scan revealed a circumscribed infarction of the genu of the internal capsule. This raised the problem of unilateral supranuclear pharyngeal palsies and of the precise anatomy of the genicular tract in the genu of the internal capsule.  相似文献   
947.
948.
Posterior ischemic optic neuropathy during general surgery   总被引:3,自引:0,他引:3  
We examined two patients who awoke with profound bilateral visual loss after operations under general anesthesia. Their fundi, initially normal, later showed bilateral optic atrophy. Neither patient showed other neurologic deficits, although one demonstrated radiologic evidence of a small cerebral infarction in the deep white matter. These patients probably suffered intraoperative infarction of the retrobulbar segments of both optic nerves, producing posterior ischemic optic neuropathy. Profound systemic hypotension may have been a contributing factor in one patient, the use of the pump-oxygenator in the other, and anemia in both.  相似文献   
949.
The pronounced susceptibility effect of macrovessels in MR bolus-tracking studies induces spots of artificially high blood flow and volume in perfusion parameter images. These high-intensity regions impede the detection of perfusion changes and lead to elevated perfusion parameters in adjacent tissues. The purpose of this work was to explore postprocessing methods to reduce the influence of macrovessel signal in dynamic MRI. After data reduction was performed with the use of a principal component analysis (PCA), an independent component analysis (ICA) was applied to separate signal components of different compartments. Based on this decomposition, the dynamic time series were reconstructed with minimized contributions of macrovessel signal and noise. The influence of the temporal resolution and signal-to-noise ratio (SNR) of the source data were investigated by means of a simulation study. A region-of-interest (ROI)-based analysis of corrected and uncorrected in vivo data demonstrated that the influence of arteries and veins was reduced at least by 50%, while gray matter (GM) and white matter (WM) tissues were nearly unaffected by the correction process. Hemodynamic parameter images of the cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) were calculated from corrected and uncorrected scans. The corrected parameter images showed a clearly reduced macrovessel signal and an improved perceptibility of microvascular perfusion changes compared to the uncorrected ones.  相似文献   
950.
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