首页 | 官方网站   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   36629篇
  免费   3577篇
  国内免费   42篇
医药卫生   40248篇
  2021年   514篇
  2020年   297篇
  2019年   513篇
  2018年   588篇
  2017年   516篇
  2016年   498篇
  2015年   520篇
  2014年   798篇
  2013年   1241篇
  2012年   1768篇
  2011年   1843篇
  2010年   983篇
  2009年   871篇
  2008年   1656篇
  2007年   1765篇
  2006年   1743篇
  2005年   1594篇
  2004年   1464篇
  2003年   1432篇
  2002年   1428篇
  2001年   1150篇
  2000年   1187篇
  1999年   1016篇
  1998年   384篇
  1997年   339篇
  1996年   363篇
  1995年   325篇
  1994年   326篇
  1993年   304篇
  1992年   930篇
  1991年   919篇
  1990年   828篇
  1989年   770篇
  1988年   678篇
  1987年   692篇
  1986年   696篇
  1985年   680篇
  1984年   552篇
  1983年   432篇
  1982年   339篇
  1981年   288篇
  1980年   256篇
  1979年   529篇
  1978年   321篇
  1977年   257篇
  1976年   279篇
  1975年   315篇
  1974年   354篇
  1973年   293篇
  1972年   273篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
71.
72.
Hemifacial spasm. Results of unilateral myectomy   总被引:1,自引:0,他引:1  
Hemifacial spasm (HFS) is a disorder characterized by unilateral involuntary spasm of the muscles innervated by the facial nerve (cranial nerve VII). The etiology is often a redundant or ectatic artery in the cerebellopontine angle that compresses the facial nerve. Neurosurgical decompression with implantation of a sponge between the ectatic artery and the facial nerve produces good results, but has a high complication rate and a poor patient acceptance rate. Various modes of peripheral neurectomy have also been advocated, but the recurrence rate is high and the preexisting functional and cosmetic eyelid deformities are exacerbated. The results of unilateral periorbital myectomy in 21 HFS patients are presented. Follow-up ranging from 1 to 7 years was available on 16 patients. Excellent or good results were obtained in 94% of these cases, and postoperative complications were minor. Transient lymphedema and forehead anesthesia are the most common complications. An unforseen benefit of periorbital myectomy surgery is the improvement or relief of lower facial contractions that occurred in 75% of patients. The authors believe the myectomy procedure is a safe, effective, predictable therapy for those HFS patients unwilling to risk a neurosurgical operation, and allows simultaneous reconstruction of associated eyelid and eyebrow deformities.  相似文献   
73.
Finger blood flow is decreased in Raynauds Phenomenon (RP). This may be due not only to vasospasm, but also to blood abnormalities. 40 patients with Raynauds Disease (RD), 28 with suspected RP (SS) and 42 with secondary Raynauds syndrome (RS) were enrolled and compared to 50 controls. Results from base-line samples show that those with RP have abnormal haemostasis and rheology whereas those with mild Raynauds, RD do not. Blood sampled after cold challenge in 15 RS patients and 15 controls show that both groups exhibit platelet activation after emersion. The degree of activation however was much more marked in the RS patients. We have shown that abnormalities of haemostasis and rheology are found in patients likely to have endothelial damage (RS). These changes are probably a consequence rather than a cause of the disease. After cold challenge the results become more abnormal and correlate with severity of disease.  相似文献   
74.
75.
BACKGROUND: Major depression has been associated with hypercortisolemia in a subset of patients with depression. Administration of exogenous cortisol and other glucocorticoids to healthy human subjects has been observed to result in a transient impairment in verbal declarative memory function. The purpose of this study was to assess the effects of the glucocorticoid, dexamethasone, on verbal declarative memory function in patients with untreated unipolar major depressive disorder (MDD). METHODS: Fifty two men and women with (n = 28) and without (n = 24) MDD received placebo or dexamethasone (1 mg and 2 mg on 2 successive days) in a double-blind, randomized fashion. Declarative memory was assessed with paragraph recall at baseline (day 1) and day 3. RESULTS: There was a significant interaction between diagnosis and drug (dexamethasone vs. placebo) on paragraph recall. In the healthy subjects, memory improved from baseline to day 3 with placebo and was unchanged with dexamethasone, whereas in MDD patients memory function showed a pattern of decreasing with placebo and improving with dexamethasone from baseline to day 3. CONCLUSIONS: These findings are consistent with an altered sensitivity of declarative memory function in MDD to regulation by glucocorticoids. Possible explanations of the findings include alterations in glucocorticoid receptors in the hippocampus or other brain regions mediating declarative memory, or differential sensitivity to dexamethasone-induced reductions in cortisol, in patients with MDD.  相似文献   
76.
One limitation of averaging individual late component event related potential (ERP) responses is that a single average ERP cannot reflect the variability of responses from epoch to epoch. In this article, we describe a method to quantify this variability and determine if any part of the overall ERP reflects a maximum variance through the use of response variance curves. We then apply this method to one disorder, schizophrenia, in which variability of information processing is hypothesized to underlie aspects of the symptomatology. Response variance curves in a group of unmedicated schizophrenic patients reveal systematic differences, maximal between 190 and 250 ms, compared with those in a group of medicated schizophrenic patients and normal control subjects.  相似文献   
77.
Longterm neurological complications of chronic, habitual cocaine abuse.   总被引:1,自引:0,他引:1  
We review and expand the results of several previously published studies on computed tomographic and electroencephalographic correlates of chronic, habitual cocaine abuse in order to present a complete spectrum of the longterm neurological complications of cocaine abuse. We argue that prolonged and frequent cocaine abuse leads to biochemical and vascular cerebral insults that eventually may cause functional and structural abnormalities affecting predominantly the fronto-temporal areas.  相似文献   
78.
Chronic recurrent Goodpasture's syndrome   总被引:1,自引:0,他引:1  
A distinctive case of Goodpasture's syndrome characterized by multiple recurrences occurring over 14 years was observed. Each recurrence followed cessation of prednisone and azathioprine therapy, and reinstitution of this therapy resulted in prompt remission. Initially, both glomerulonephritis and hemoptysis were prominent clinical features. In recent years, hemoptysis has been the predominant clinical problem. This and other cases suggest that Goodpasture's syndrome may comprise a wider disease spectrum than generally appreciated.  相似文献   
79.
Chiari II malformation: MR imaging evaluation   总被引:4,自引:0,他引:4  
The purpose of this study was to explore the value of high-detail MR imaging in the diagnosis of the Chiari II malformation. Twenty-four patients with known Chiari II malformation as diagnosed by CT scanning were evaluated with cranial MR scans. Two patients also had spine scans. The sagittal-plane images were the most informative, and abnormalities of the telencephalon, diencephalon, mesencephalon, rhomboencephalon, upper spinal cord, and mesencephalon were shown extremely well. We found MR to be an easy and accurate method for demonstrating the abnormalities of the Chiari II malformation, and it is our procedure of choice.  相似文献   
80.
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-23

京公网安备 11010802026262号