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   925748篇
  免费   63647篇
  国内免费   2454篇
耳鼻咽喉   12776篇
儿科学   29362篇
妇产科学   26821篇
基础医学   129997篇
口腔科学   26182篇
临床医学   76750篇
内科学   189145篇
皮肤病学   19486篇
神经病学   73366篇
特种医学   36983篇
外国民族医学   337篇
外科学   145100篇
综合类   19319篇
一般理论   258篇
预防医学   67692篇
眼科学   20490篇
药学   65596篇
  1篇
中国医学   1969篇
肿瘤学   50219篇
  2018年   10116篇
  2017年   7835篇
  2016年   8377篇
  2015年   9493篇
  2014年   13266篇
  2013年   20380篇
  2012年   27738篇
  2011年   29547篇
  2010年   17611篇
  2009年   16521篇
  2008年   27840篇
  2007年   29557篇
  2006年   29578篇
  2005年   29064篇
  2004年   27680篇
  2003年   26754篇
  2002年   26260篇
  2001年   41778篇
  2000年   42979篇
  1999年   36578篇
  1998年   10057篇
  1997年   9219篇
  1996年   9145篇
  1995年   8501篇
  1994年   8127篇
  1993年   7625篇
  1992年   28389篇
  1991年   27135篇
  1990年   26548篇
  1989年   25488篇
  1988年   23675篇
  1987年   23270篇
  1986年   22349篇
  1985年   21239篇
  1984年   15878篇
  1983年   13527篇
  1982年   8113篇
  1979年   14640篇
  1978年   10237篇
  1977年   8659篇
  1976年   8170篇
  1975年   8999篇
  1974年   10751篇
  1973年   10213篇
  1972年   9696篇
  1971年   8963篇
  1970年   8624篇
  1969年   8062篇
  1968年   7724篇
  1967年   7117篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
131 patients with resectable, node-positive breast cancer were treated at the National Institute for Cancer Research of Genoa, Italy with a systemic adjuvant regimen based on 14 cycles of chemotherapy, immunostimulation with levamisole, and--for postmenopausal patients--hormone therapy with tamoxifen. The present evaluation is performed eleven years after the admission of the first patient: so far, 75 patients (57.3%) have relapsed and 52 (39.7%) have died. An analysis of prognostic factors for relapse and death shows that the number of positive axillary lymph nodes and the dimension of the primary tumor are significantly associated with survival and relapse-free survival, while age and menopausal status are not.  相似文献   
103.
The Dundee Memory Clinic was established in 1991. This paper reviews the diagnosis of the first 150 attenders and compares the findings with those of other memory clinics.  相似文献   
104.
105.
106.
PURPOSETo use functional MR imaging to measure the effect of frequency (pitch), intensity (loudness), and complexity of auditory stimuli on activation in the primary and secondary auditory cortexes.METHODSMultiplanar echo-planar images were acquired in healthy subjects with normal hearing to whom auditory stimuli were presented intermittently. Functional images were processed from the echo-planar images with conventional postprocessing methods. The stimuli included pure tones with a single frequency and intensity, pure tones with the frequency stepped between 1,000, 2,000, 3,000, or 4,000 Hz, and spoken text. The pixels activated by each task in the transverse temporal gyrus (TTG) and the auditory association areas were tabulated.RESULTSThe pure tone task activated the TTG. The 1,000-Hz tone activated significantly more pixels in the TTG than did the 4,000-Hz tone. The 4,000-Hz tone activated pixels primarily in the medial TTG, whereas the 1,000-Hz tone activated more pixels in the lateral TTG. Higher intensity tones activated significantly more pixels than did lower intensity tones at the same frequency. The stepped tones activated more pixels than the pure tones, but the difference was not significant. The text task produced significantly more activation than did the pure tones in the TTG and in the auditory association areas. The more complex tasks (stepped tones and listening to text) tended to activate more pixels in the left hemisphere than in the right, whereas the simpler tasks activated similar numbers of pixels in each hemisphere.CONCLUSIONAuditory stimuli activate the TTG and the association areas. Activation in the primary auditory cortex depends on frequency, intensity, and complexity of the auditory stimulus. Activation of the auditory association areas requires more complex auditory stimuli, such as the stepped tone task or text reading.  相似文献   
107.
108.
A retrospective chart review of 43 patients who underwent technetium 99m (Tc-99m) sestamibi scans from June 1995 to January 1997 was performed. Only those who underwent subsequent parathyroid exploration with excision were included in the study. Twenty subjects (13 women and seven men) were included in the study. Ages ranged from 21 to 84 years (mean, 58 years). All patients had laboratory values and clinical findings consistent with primary hyperparathyroidism. Two patients had preoperative magnetic resonance imaging (MRI) scans (one patient with recurrent disease), and one had a preoperative computed tomography (CT) scan. The remaining patients had the sestamibi scan as the only preoperative localization study. There were 18 pathologic diagnoses of parathyroid adenoma and two of parathyroid hyperplasia. Sestamibi failed to correctly identify the location of the parathyroid lesion in two cases. In 18 cases the preoperative sestamibi scan correctly localized the lesion, a predictive value of 90%. We conclude that the Tc-99m sestamibi scan is an accurate preoperative tool that can be used as a single modality to localize parathyroid adenomas.  相似文献   
109.
The diagnosis of acute disseminated encephalomyelitis (ADEM) is frequently missed or delayed with consequent delay in instituting therapy in the crucial phase of the illness. The role of MRI in the diagnosis of ADEM is well established, however, the value of its early utilization of treatment on the outcome of patients has not been adequately stressed. Three patients with ADEM are described. Delay in the diagnosis of the first was associated with severe sequelae, while in the other two early diagnosis and institution of corticosteroid therapy which was facilitated by MRI, was associated with a better outcome. MRI should be carried out early once the diagosis of ADEM is entertained.  相似文献   
110.
Tissue specimens from the large bowel of 18 patients with long-standing slow transit constipation were investigated to determine the distribution and density of several neuropeptides and amines in the enteric nerve system, and also of endocrine cells in comparison to normal individuals. CGRP (calcitonin gene-related peptide), galanin, glucagon, GRP (gastrin-releasing peptide), metenkephalin, motilin, neuropeptide Y (NPY), PACAP, peptide YY (PYY), serotonin, somatostatin, substance P and VIP were studied by immunohistochemistry. Tissue concentrations of VIP, substance P and galanin were also measured by radioimmunoassay. Significantly increased VIP, SP and galanin contents were found in specimens from the ascending colon. Levels of VIP and galanin were also increased in the transverse colon. Immunohistochemistry revealed only marginal changes with an increased density of PACAP nerve fibres in the smooth muscle and of VIP and PACAP nerves in the myenteric plexus of the transverse colon. In the descending colon substance P and NPY immunoreactivity were also increased in the myenteric plexus while the density of VIP nerve fibres was reduced in the mucosa/submucosa. The frequency of PYY-containing cells and the 5-HT-containing cells in the ascending colon was significantly increased in the constipated patients.  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