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   498篇
  免费   27篇
  国内免费   1篇
儿科学   9篇
妇产科学   5篇
基础医学   59篇
临床医学   34篇
内科学   48篇
皮肤病学   11篇
神经病学   18篇
特种医学   39篇
外科学   158篇
综合类   1篇
预防医学   37篇
眼科学   1篇
药学   30篇
肿瘤学   76篇
  2023年   3篇
  2022年   1篇
  2021年   2篇
  2020年   10篇
  2019年   7篇
  2018年   14篇
  2017年   5篇
  2016年   7篇
  2015年   7篇
  2014年   19篇
  2013年   22篇
  2012年   30篇
  2011年   40篇
  2010年   21篇
  2009年   21篇
  2008年   37篇
  2007年   39篇
  2006年   39篇
  2005年   17篇
  2004年   30篇
  2003年   35篇
  2002年   28篇
  2001年   15篇
  2000年   20篇
  1999年   10篇
  1998年   4篇
  1997年   4篇
  1996年   2篇
  1995年   1篇
  1994年   3篇
  1993年   6篇
  1992年   5篇
  1991年   1篇
  1990年   7篇
  1989年   6篇
  1988年   2篇
  1987年   2篇
  1983年   1篇
  1981年   1篇
  1977年   1篇
  1965年   1篇
排序方式: 共有526条查询结果,搜索用时 15 毫秒
1.
In this study the organization of information processing in a selective search task was examined by analyzing event-related potentials. This task consisted of searching for target letters in a relevant (attended) color. The ERPs revealed two different effects of attention: an early occipital negativity (+/- 150 ms) reflecting feature-specific attention, and a later, central N2b component (+/- 240 ms) reflecting covert orienting of attention. A later, prolonged negativity (search-related negativity) (+/- 300 ms), maximal at Cz, was related to controlled search to letters in the attended color. Detection of relevant targets resulted in a parietal P3b component. Depending on stimulus presentation conditions an earlier response to both attended and unattended targets was found: an N2 component (+/- 250 ms). In these same conditions, C'3-C'4 asymmetries (Corrected Motor Asymmetries--CMA) suggested motor activation at +/- 300 ms, in the same time range as search-related negativity. It was argued that N2 and CMA suggest the existence of a preattentive target detection system, operating in parallel with a slower serial attentive system, as reflected by N2b and search negativity.  相似文献   
2.
3.
Recent advances in the study of cardiac development have shown the relevance of addition of myocardium to the primary myocardial heart tube. In wild‐type mouse embryos (E9.5–15.5), we have studied the myocardium at the venous pole of the heart using immunohistochemistry and 3D reconstructions of expression patterns of MLC‐2a, Nkx2.5, and podoplanin, a novel coelomic and myocardial marker. Podoplanin‐positive coelomic epithelium was continuous with adjacent podoplanin‐ and MLC‐2a‐positive myocardium that formed a conspicuous band along the left cardinal vein extending through the base of the atrial septum to the posterior myocardium of the atrioventricular canal, the atrioventricular nodal region, and the His‐Purkinje system. Later on, podoplanin expression was also found in the myocardium surrounding the pulmonary vein. On the right side, podoplanin‐positive cells were seen along the right cardinal vein, which during development persisted in the sinoatrial node and part of the venous valves. In the MLC‐2a‐ and podoplanin‐positive myocardium, Nkx2.5 expression was absent in the sinoatrial node and the wall of the cardinal veins. There was a mosaic positivity in the wall of the common pulmonary vein and the atrioventricular conduction system as opposed to the overall Nkx2.5 expression seen in the chamber myocardium. We conclude that we have found podoplanin as a marker that links a novel Nkx2.5‐negative sinus venosus myocardial area, which we refer to as the posterior heart field, with the cardiac conduction system. Anat Rec, 290:115–122, 2007. © 2006 Wiley‐Liss, Inc.  相似文献   
4.
5.
6.
Establishing the diagnosis in patients with lower urinary tract symptoms is complicated. Several tests have been developed, but the importance of each of these tests in the diagnostic process is not well understood. This paper describes the methods used to evaluate diagnostic tests, ranging from traditional sensitivity and specificity to more sophisticated techniques such as logistic regression and neural networks.  相似文献   
7.

Purpose

The reliability of the International Prostate Symptom Score (I-PSS) was tested in patients with lower urinary tract symptoms and/or benign prostatic hyperplasia.

Materials and Methods

A total of 71 consecutive men with benign prostatic hyperplasia and/or lower urinary tract symptoms was asked to complete the I-PSS at baseline and 8 weeks later. At the second visit the physician also completed the I-PSS according to the complaints of the patient. Variability between both scores was evaluated by calculation of duplo errors and results were compared to the clinical data.

Results

A considerable variability existed between the I-PSS results obtained at baseline and 8 weeks. The duplo error was 4.3. In a regression analysis of I-PSS, including all clinical parameters, only free flow had some predictive value for I-PSS outcomes.

Conclusions

It is important to consider the variability of the I-PSS score when making decisions concerning treatment.  相似文献   
8.
In 1955, 234 men and 116 women died from bladder cancer in the Netherlands. In 1988 the numbers were 794 and 317 respectively. After adjusting for the ageing of the Dutch population since 1955, female mortality rates per 10(5) person-years appear to be very stable: 2.9 from 1955 to 1959 and 3.0 from 1985 to 1988. By contrast, an increasing trend exists in males. From 1955 to 1959 and from 1985 to 1988, bladder cancer mortality rates per 10(5) person-years were 7.5 and 12.4 respectively. For men in particular, increasing mortality (and incidence) rates are seen all over the world. In many cases this increasing trend is thought to originate from a higher risk of dying from bladder cancer in successive birth cohorts rather than from a higher risk in successive calendar periods. This so-called cohort effect is explained by changes in smoking behaviour in the male population. Statistical modelling of bladder cancer mortality data from 1955 to 1988 in the Netherlands shows that the increasing temporal trend in men can also be described as a cohort effect. The risk of dying from bladder cancer increases from the 1875 birth cohort to the 1910 birth cohort, but decreases thereafter. It is concluded that this decreasing risk for generations born after 1910 will probably result in a decreasing trend in mortality in the near future, when more and more of these "youngsters" reach the age of 70+.  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