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   4190篇
  免费   390篇
  国内免费   2篇
耳鼻咽喉   59篇
儿科学   125篇
妇产科学   78篇
基础医学   608篇
口腔科学   92篇
临床医学   545篇
内科学   513篇
皮肤病学   93篇
神经病学   618篇
特种医学   177篇
外科学   583篇
综合类   112篇
一般理论   2篇
预防医学   363篇
眼科学   89篇
药学   246篇
中国医学   29篇
肿瘤学   250篇
  2021年   50篇
  2020年   37篇
  2019年   53篇
  2018年   54篇
  2017年   36篇
  2016年   36篇
  2015年   57篇
  2014年   99篇
  2013年   130篇
  2012年   160篇
  2011年   154篇
  2010年   105篇
  2009年   97篇
  2008年   160篇
  2007年   185篇
  2006年   198篇
  2005年   198篇
  2004年   152篇
  2003年   156篇
  2002年   130篇
  2001年   126篇
  2000年   141篇
  1999年   118篇
  1998年   60篇
  1997年   69篇
  1996年   64篇
  1995年   59篇
  1994年   44篇
  1993年   41篇
  1992年   110篇
  1991年   102篇
  1990年   138篇
  1989年   113篇
  1988年   97篇
  1987年   104篇
  1986年   81篇
  1985年   98篇
  1984年   73篇
  1983年   62篇
  1982年   42篇
  1981年   42篇
  1980年   28篇
  1979年   49篇
  1978年   48篇
  1977年   28篇
  1976年   29篇
  1975年   28篇
  1974年   29篇
  1973年   36篇
  1972年   29篇
排序方式: 共有4582条查询结果,搜索用时 203 毫秒
1.

Purpose

To quantify eating disorder (ED) stability and diagnostic transition among a community-based sample of adolescents and young adult females in the United States.

Methods

Using 11 prospective assessments from 9,031 U.S. females ages 9–15 years at baseline of the Growing Up Today Study, we classified cases of the following EDs involving bingeing and purging: bulimia nervosa (BN), binge ED, purging disorder (PD), and subthreshold variants defined by less frequent (monthly vs. weekly) bingeing and purging behaviors. We measured number of years symptomatic and probability of maintaining symptoms, crossing to another diagnosis, or resolving symptoms across consecutive surveys.

Results

Study lifetime disorder prevalence was 2.1% for BN and roughly 6% each for binge ED and PD. Most cases reported symptoms during only one survey year. Twenty-six percent of cases crossed between diagnoses during follow-up. Among participants meeting full threshold diagnostic criteria, transition from BN was most prevalent, crossing most frequently from BN to PD (12.9% of BN cases). Within each disorder phenotype, 20%–40% of cases moved between subthreshold and full threshold criteria across consecutive surveys.

Conclusions

Diagnostic crossover is not rare among adolescent and young adult females with an ED. Transition patterns from BN to PD add support for considering these classifications in the same diagnostic category of disorders that involve purging. The prevalence of crossover between monthly and weekly symptom frequency suggests that a continuum or staging approach may increase utility of ED classification for prognostic and therapeutic intervention.  相似文献   
2.
3.
4.
5.
The recent development of brain atlases with computer graphics templates, and of huge databases of neurohistochemical data on the internet, has forced a systematic re-examination of errors associated with comparing histological features between adjacent sections of the same brain, between brains treated in the same way, and between brains from groups treated in different ways. The long-term goal is to compare as accurately as possible a broad array of data from experimental brains within the framework of reference atlases. Main sources of error, each of which ideally should be measured and minimized, include intrinsic biological variation, linear and nonlinear distortion of histological sections, plane of section differences between each brain, section alignment problems, and sampling errors. These variables are discussed, along with approaches to error estimation and minimization in terms of a specific example—the distribution of neuroendocrine neurons in the rat paraventricular nucleus. Based on the strategy developed here, the main conclusion is that the best long-term solution is a high-resolution 3D computer graphics model of the brain that can be sliced in any plane and used as the framework for quantitative neuroanatomy, databases, knowledge management systems, and structure–function modeling. However, any approach to the automatic annotation of neuroanatomical data—relating its spatial distribution to a reference atlas—should deal systematically with these sources of error, which reduce localization reliability.  相似文献   
6.
Twelve patients in whom radial artery infections developed after catheterization in an intensive care unit over a 2-year period were reviewed. The incidence of local infection was 0.4%. An increased risk of infection was associated with prolonged catheterization (greater than 4 days). Aneurysms developed in five patients. Signs of septic emboli were present in two patients, including Osler's nodes, Janeway's lesions, and fingertip infarcts. In 6 of the 12 patients, the radial artery infection resolved with antibiotic treatment alone. The five patients with infected aneurysms were treated successfully with antibiotics and surgical excision. The radial artery was reconstructed by use of a vein graft in one patient. We believe that patients not responding promptly to antibiotics or patients with infected aneurysms are best treated by surgical excision.  相似文献   
7.
8.
用体外培养的人的伪表皮作为模型,进行药物毒理学作用的研究,观察了二甲亚砜(DMSO)在不同浓度和不同接触时间条件下,对人的伪表皮细胞脱氧核糖核酸(DNA)、核糖核酸(RNA)和蛋白质合成的影响:随着接触时间的延长,DNA、RNA和蛋白质合成均受抑制。低浓度条件下(1%),DNA、RNA和蛋白质合成增加;在15~50%浓度下,DNA和蛋白质合成抑制,而RNA合成仍增加;在高浓度条件下(70%~100%),DNA、RNA和蛋白质合成均明显抑制。  相似文献   
9.
Using the unique resources of the Rochester Epidemiology Project for population-based studies, we identified 629 Olmsted County, Minn., residents who fulfilled the 1988 International Headache Society criteria for newly diagnosed migraine over a 3-year period. Over 6,400 patient records from several diagnostic rubrics were screened; a substantial proportion of cases had been 'signed-out' to diagnoses other than 'migraine headache'. Medical records were reviewed by two trained nurses who abstracted supporting data for two neurologists. The neurologists determined whether each case met eligibility requirements and assigned a headache diagnosis by consensus. The diagnostic criteria offered some flexibility and were adapted to retrospective record-based research. Most records contained enough information to effectively classify the headache, although information on the frequency and duration of attacks proved to be problematic. A validation re-abstraction of a 10% sample of cases was undertaken with acceptable reproducibility of symptoms and diagnosis. Our study shows that migraine headache can be studied retrospectively through existing detailed medical records.  相似文献   
10.
CT appearance of cervical lipoblastoma   总被引:1,自引:0,他引:1  
We describe a case of lipoblastoma causing respiratory symptoms in an infant, where CT was useful in establishing the diagnosis and demonstrating the extent of involvement so that complete surgical resection could be planned.  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