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   8078篇
  免费   805篇
  国内免费   29篇
耳鼻咽喉   67篇
儿科学   377篇
妇产科学   229篇
基础医学   882篇
口腔科学   126篇
临床医学   1018篇
内科学   1432篇
皮肤病学   73篇
神经病学   743篇
特种医学   307篇
外科学   1407篇
综合类   205篇
现状与发展   20篇
一般理论   2篇
预防医学   775篇
眼科学   190篇
药学   540篇
中国医学   6篇
肿瘤学   513篇
  2023年   69篇
  2021年   112篇
  2020年   84篇
  2019年   104篇
  2018年   165篇
  2017年   129篇
  2016年   121篇
  2015年   142篇
  2014年   167篇
  2013年   293篇
  2012年   303篇
  2011年   355篇
  2010年   201篇
  2009年   192篇
  2008年   324篇
  2007年   337篇
  2006年   356篇
  2005年   296篇
  2004年   294篇
  2003年   275篇
  2002年   269篇
  2001年   297篇
  2000年   294篇
  1999年   279篇
  1998年   150篇
  1997年   114篇
  1996年   127篇
  1995年   109篇
  1994年   91篇
  1993年   82篇
  1992年   197篇
  1991年   186篇
  1990年   188篇
  1989年   156篇
  1988年   172篇
  1987年   139篇
  1986年   153篇
  1985年   145篇
  1984年   135篇
  1983年   110篇
  1982年   71篇
  1981年   63篇
  1979年   108篇
  1978年   81篇
  1977年   70篇
  1976年   52篇
  1975年   75篇
  1974年   74篇
  1973年   77篇
  1972年   63篇
排序方式: 共有8912条查询结果,搜索用时 62 毫秒
11.
Objective Approximately 10% of patients with neurofibromatosis I (NFI) patients will have central nervous system (CNS) tumors. The most common of these are hypothalamic–optic gliomas, followed by brainstem and cerebellar pilocytic astrocytomas. While isolated pilocytic astrocytomas in NFI are well described, the appearance of multiple pilocytic astrocytomas in an individual patient is less common. The most frequent combination in NFI patients with more than one pilocytic astrocytoma is optic tract/hypothalamic and brainstem. Other combinations are exceedingly rare; multiple pilocytic astrocytomas have only been reported once in the cerebral hemispheres in a patient with NFI. This report presents the first documented case, to our knowledge, of multiple pilocytic astrocytomas in the cerebellum of a patient with NF1. Methods Case report. Conclusion The finding of multiple cerebellar pilocytic astrocytomas in a patient with NF1 is important because it expands the spectrum of presentations for patients with NF1 and also highlights specific diagnostic and therapeutic challenges faced by the treating physicians. The genetic and molecular basis of NF1 is reviewed. Strategies of diagnosis and treatment outlined here are relevant to both patients with NF1 and all patients with multiple posterior fossa tumors.  相似文献   
12.
We compared three maintenance immunosuppressive regimens in a rapid discontinuation of prednisone protocol. From March 1, 2001, through December 31, 2003, 239 first and second kidney transplant recipients (166 LD; 73 DD) were randomized. All recipients were treated with Thymoglobulin; all received steroids intraoperatively and for 5 days postoperatively. Randomization was to cyclosporine-mycophenolate mofetil (n = 85); high-level tacrolimus (TAC) (8-12 ng/mL)-low-level sirolimus (SRL) (3-7 ng/mL) (n = 72); or low-level TAC (3-7 ng/mL)-high-level SRL (8-12 ng/mL) (n = 82). We found no difference at 24 months between groups in patient, graft, death-censored graft, or acute rejection-free graft survival, or in kidney function. Wound complications were more common in SRL-treated recipients (p = 0.02); we found no other differences between groups in complication rates. Our data suggest that excellent patient and graft survival and low rejection rates can be obtained using a variety of maintenance protocols without prednisone.  相似文献   
13.
14.
PURPOSE. The purpose of the study was to develop a scale to calculate college students' powerlessness regarding health service barriers (PHSB). METHODS. Scale items were generated to represent two domains of interest: powerlessness and college students' powerlessness regarding health service barriers. The final 20-item instrument was subjected to multiple measures of validity with college students and panels of nurse experts in the area of nursing diagnosis. Reliability was assessed by two samples (n = 92 and n = 33) of college-age students. A final administration was conducted with 197 college students. FINDINGS. The PHSB scale was determined to be an accurate and consistent measure. CONCLUSIONS. This instrument will provide a reliable and valid measure to conduct research.  相似文献   
15.
16.
17.
Feeding, a behavior regulated by the central nervous system (CNS), includes the acquisition of specific essential nutrients and the maintenance of energy balance. Modulation of feeding behavior is a normal part of survival, but certain pathological conditions interrupt or modify regulatory aspects of feeding, thereby leading to inappropriate intake. This review examines aspects of metabolism associated with the anorexia seen in animals suffering from protein-energy malnutrition (PEM). The main focus is the indispensable amino acid histidine (His), the biosynthetic precursor of the neurotransmitter histamine (HA). In kwashiorkor-like PEM, His is elevated in plasma and brain, whereas all other indispensable amino acids are decreased. The elevation of His in the brain is to concentrations five times normal. Because the rate of HA synthesis in the brain is a function of the His concentration, His elevation raises the possibility of a profound direct effect of CNS function. In children, PEM consistently produces the symptoms of depressed food intake, edema, growth failure, and psychomotor changes. One known central effect of HA is the stimulation of ACTH and corticosteroid release. Based on these observations, the hypothesis being examined is as follows: one component of the pathophysiological neuroregulation of food intake involved the His-induced variation of HA concentration in the hypothalamus and the subsequently altered neurochemical activity at the corticotropin-releasing factor (CRF) neurons o the paraventricular nucleus (PVN).  相似文献   
18.
19.
20.
We studied the role of theophylline on outcome of status epilepticus (SE) in children. During a two-year-period, 16 of 114 episodes of SE occurred in children receiving theophylline. At the onset of SE, theophylline blood levels were elevated in 8 episodes, and were therapeutic or subtherapeutic in 8 episodes. In the 8 episodes of SE with elevated theophylline levels, one child died and three suffered permanent new neurologic deficits. In the 8 episodes of SE with normal or low theophylline levels, only one child had a transient deficit. The occurrence of death or disability in 4 of 8 episodes of SE with elevated theophylline was considerably higher than the 23% incidence of death or persistent CNS deficit in the overall series of 114 episodes of SE. We conclude that theophylline, at toxic levels, is a significant factor in increased morbidity. We suspect that the hypoxia from the respiratory disorder for which theophylline was used, and the reduced cerebral blood flow known to occur with theophylline led to a failure to compensate for the increased cerebral metabolic rate of SE, thus increasing the risk of a poor outcome.  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