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   2752篇
  免费   139篇
  国内免费   69篇
耳鼻咽喉   23篇
儿科学   151篇
妇产科学   47篇
基础医学   381篇
口腔科学   58篇
临床医学   322篇
内科学   494篇
皮肤病学   60篇
神经病学   238篇
特种医学   308篇
外科学   359篇
综合类   35篇
一般理论   1篇
预防医学   93篇
眼科学   76篇
药学   144篇
肿瘤学   170篇
  2021年   31篇
  2020年   30篇
  2019年   36篇
  2018年   47篇
  2017年   32篇
  2016年   35篇
  2015年   55篇
  2014年   76篇
  2013年   110篇
  2012年   110篇
  2011年   107篇
  2010年   96篇
  2009年   91篇
  2008年   103篇
  2007年   141篇
  2006年   108篇
  2005年   89篇
  2004年   84篇
  2003年   76篇
  2002年   71篇
  2001年   84篇
  2000年   59篇
  1999年   57篇
  1998年   75篇
  1997年   83篇
  1996年   80篇
  1995年   69篇
  1994年   48篇
  1993年   59篇
  1992年   42篇
  1991年   36篇
  1990年   53篇
  1989年   65篇
  1988年   40篇
  1987年   59篇
  1986年   37篇
  1985年   49篇
  1984年   31篇
  1983年   35篇
  1982年   30篇
  1981年   27篇
  1980年   33篇
  1979年   18篇
  1978年   13篇
  1977年   18篇
  1976年   11篇
  1975年   19篇
  1970年   13篇
  1969年   18篇
  1966年   12篇
排序方式: 共有2960条查询结果,搜索用时 15 毫秒
1.
Electrocardiograms were evaluated in 39 children and adolescents before and after the clinical use of imipramine and desipramine. The average increase in PR interval was 0.01 seconds. The PR interval increased by 0.02 seconds in 11 subjects, and a new first-degree atrioventricular block developed in two subjects. These changes were not related to the choice between imipramine and desipramine, the dose, or the method of administration. An increase in PR interval by 0.02 seconds or more did correlate with having an abnormality disclosed on a pretreatment electrocardiogram. The average increase in PR interval was 0.007 seconds for subjects with normal baseline electrocardiograms and 0.019 seconds for subjects with conduction and nonconduction abnormalities disclosed in baseline tracings. None of the electrocardiogram changes resulted in adverse clinical consequences.  相似文献   
2.
3.
OBJECTIVE: To develop a distance measure based methodology to support the morphological evaluation of high grade prostatic intraepithelial neoplasia (PIN), a direct precursor of prostate cancer. METHODS: Eight morphological and cellular features were analysed in 20 cases of high grade PIN found in radical prostatectomy specimens from patients with adenocarcinoma. The diagnostic distance was evaluated to measure the extent to which the feature outcomes of the individual high grade PIN cases differed from the expected outcome profile of normal prostate, low and high grade PIN, and cribriform and large acinar adenocarcinoma. The belief value for high grade PIN was evaluated with a Bayesian belief network (BBN). RESULTS: Complete separation existed between the cumulative absolute diagnostic distances of these 20 cases from the prototype feature outcomes of high grade PIN and normal prostate the values for which were < or = 3 (range 0 to 3) and > or = 9 (range 9 to 15), respectively. The distances from low grade PIN (range 3 to 9), cribriform adenocarcinoma (range 2 to 8), and large acinar adenocarcinoma (range 5 to 10) were intermediate and showed overlap in their distribution. When taking into consideration whether the severity of feature changes was increasing or decreasing in comparison with the category prototype outcomes, the cumulative directional diagnostic distances from high grade PIN ranged from -3 to +3. Positive distance values were seen relative to low grade PIN (range +3 to +9) and relative to normal prostate (range +9 to +15). Negative values were found relative to cribriform adenocarcinoma (range -8 to +2). The distance values from large acinar adenocarcinoma ranged from -2 to +4 and partly overlapped with those from the high grade PIN category. A bivariate scattergram derived from both diagnostic distance measures showed excellent separation between the groups' distances. BBN analysis confirmed the morphology based diagnosis. The distance evaluation resulted in 18 cases whose belief value for high grade PIN ranged from 0.60 to 0.87. In the remaining two cases the results of the BBN analysis showed a belief value of 0.50 and 0.57 for low grade PIN and of 0.49 and 0.38 for high grade PIN, respectively. CONCLUSIONS: Distance measure based methodology represents a useful diagnostic decision support tool for the accurate evaluation of high grade PIN.  相似文献   
4.
5.
6.
Pre-clinical psychiatric emergency situations (PES) have been identified to be the third major reason for emergency physician (EP) calls with a frequency of approximately 10%. Until now, there are no investigations about regional differences between urban and rural regions in frequencies, diagnoses, or treatment necessities of PES. A retrospective analysis of all anonymised EP protocols of one year in a metropolitan (Hamburg) and a rural region (Schaumburg County) was performed with the same methodological approach. In both regions, the frequency of PES was revealed to be near 10%. Gender and age of psychiatric patients as well as reasons for calls were comparable. In Schaumburg County, much less disturbances due to illegal drugs were observed. However, more patients had to be treated because of suicide attempts and alcoholism. All in all, disturbances seemed less life-threatening than in the metropolitan region. In conclusion, frequency and kind of PES do not differ substantially between rural and urban regions. Considering the prevalence of PES, the particularities in diagnosis and treatment and the dissipation of institutionalised psychiatric care mainly in rural regions, more training in psychiatric subjects is needed.  相似文献   
7.
Anastomotic leaks are still among the most common severe postoperative complications and account for the majority of postoperative deaths after esophagectomy and gastrectomy. Every disturbance of the normal postoperative course should trigger surgeons to consider an underlying anastomotic leak and initiate a specific diagnostic workup. This includes direct endoscopic inspection of the anastomosis to evaluate the vitality of the anastomosed organs and the size of the leak. Adequate external drainage of the leak and prevention of further contamination are the primary therapeutic goals. Selection of therapy is guided by the available modalities for sufficiently draining the leak and avoiding sepsis. The spectrum of therapeutic options ranges from simple opening of the neck incision in cervical esophageal anastomoses, interventional placement of drains, to endoscopic intervention with closure of the fistula or placement of stents, and reoperation with exclusion, diversion, or discontinuity resection.  相似文献   
8.
Fluorescent tracers are commonly used in fluorophotometric studies of ocular fluids and tissues that contain background protein. Background-protein concentrations were found to decrease or increase significantly the measure of fluorescence emitted from solutions containing sodium fluorescein, fluorescein-labeled dextran, or fluorescein-labeled horseradish peroxidase. The effect of background protein on fluorescence was expressed as a function of the specific fluorescent tracer, tracer concentration, and background-protein concentration; it can be corrected in the analysis of fluorophotometric data. Fluorophotometric studies--particularly those in which the background-protein level is expected to be abnormally high, such as postoperative and pathologic studies--may need to include either a data correction based on measured effects of background protein on tracer fluorescence or, in the case of clinical investigations, recognize at least the potential for a range of possible interpretations.  相似文献   
9.
10.
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