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   161760篇
  免费   10351篇
  国内免费   1213篇
耳鼻咽喉   2260篇
儿科学   3027篇
妇产科学   3742篇
基础医学   24089篇
口腔科学   3346篇
临床医学   15268篇
内科学   30868篇
皮肤病学   4341篇
神经病学   12064篇
特种医学   8086篇
外科学   21942篇
综合类   2172篇
现状与发展   5篇
一般理论   81篇
预防医学   9745篇
眼科学   4311篇
药学   13674篇
中国医学   1597篇
肿瘤学   12706篇
  2023年   989篇
  2022年   2749篇
  2021年   4852篇
  2020年   2477篇
  2019年   3592篇
  2018年   4413篇
  2017年   3244篇
  2016年   4199篇
  2015年   5655篇
  2014年   6928篇
  2013年   8385篇
  2012年   12678篇
  2011年   12319篇
  2010年   7258篇
  2009年   6082篇
  2008年   9268篇
  2007年   9142篇
  2006年   8399篇
  2005年   8006篇
  2004年   7145篇
  2003年   6197篇
  2002年   5383篇
  2001年   4379篇
  2000年   4028篇
  1999年   3265篇
  1998年   1309篇
  1997年   989篇
  1996年   950篇
  1995年   863篇
  1994年   753篇
  1993年   644篇
  1992年   1572篇
  1991年   1570篇
  1990年   1353篇
  1989年   1239篇
  1988年   1155篇
  1987年   1030篇
  1986年   1010篇
  1985年   882篇
  1984年   644篇
  1983年   565篇
  1982年   400篇
  1981年   377篇
  1980年   339篇
  1979年   521篇
  1978年   407篇
  1977年   390篇
  1976年   343篇
  1974年   358篇
  1973年   327篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Behavioral state-specific changes in human hippocampal theta activity   总被引:1,自引:0,他引:1  
Although there has been extensive examination of the behavioral and physiologic correlates of hippocampal theta activity in animals, the human literature consists of a single case study. We investigated the differential effects of four behavioral states on human hippocampal theta activity in 16 epilepsy surgery patients. Behavioral conditions included resting eyes closed (RC), resting eyes open (RO), eyes open with auditory word activation (AW), and eyes open with visuospatial activation (VS). Hippocampal theta activity decreased during both RO and VS compared to both RC and AW. There were reciprocal changes in delta activity. Comparisons of RO to VS and of RC to AW were nonsignificant. The results demonstrate state-specific changes in human hippocampal theta and are consistent with the animal literature that relates hippocampal theta to sensorimotor integration and forebrain volitional mechanisms.  相似文献   
22.
Originally described by Rosen in 1983, syringomatous nipple adenoma (SAN) is a tumor of disputed histogenesis, which can be problematic both diagnostically and therapeutically. 1 It is a benign primary tumor of breast epithelium with histology similar to that of the syringoma. In the current case, we describe a 40-year-old female with this lesion occurring within a supernumerary breast. This case represents, to our knowledge, the first such reported case, and represents a significant finding as its presence could lend some confusion as to whether or not this represents a benign primary process of breast or a potentially infiltrative tumor of the skin.  相似文献   
23.
24.
25.
Background/aims: The objective and quantitative assessment of the skin is important in medical and cosmeceutical research. Assessment of color is an important element for analyzing the surface of the skin, which is usually determined subjectively by a doctor or using color analysis devices. These devices, however, cannot provide correct color information because color is construed from the mean value of the observation region, and analysis of color distribution is impossible. The purpose of this paper is to develop an objective analysis method to permit skin color measurement of each pixel unit of an image and analyze the distribution of skin surface color. Methods: The Skin Color Distribution Analyzer (SCDA) is an analysis method newly developed at the Research Institute for Skin Image at Korea University. The SCDA system presented in this paper performed a novel form of quantitative and objective analysis of skin color distribution using each pixel color model parameter found in image wavelength information. In this paper, distribution analysis was conducted on normal skin and skin lesions and skin affected by artificially induced irritant contact dermatitis and pigmented nevous. The method selected a grade using a color model parameter. Twenty healthy Korean males participated in this study. A comparative study of the eight anatomical areas was performed, including the exposure and non‐exposure parts and the medial aspect and the lateral aspect of the forearm. A reliability test for the SCDA system was also conducted with a spectrometer (SPEC) using the color analysis method. Results: Each skin lesion was precisely segmented by grade and each parameter hada different statistical significance for results of analysis of distribution in pigmented nevous and the artificially induced irritant contact dermatitis. Parameters L*, b*, a*, and EI showed salient traits. Showed resemble measured result in the SCDA system and the SPEC of normal skin. The exposed site, in comparison with the non‐exposed site, showed a notable difference in the L* parameter and a significant statistical difference in the x and z parameters, except b*. The comparison of the medial and lateral aspects of the forearm showed a notable difference in the L* parameter and a significant statistical difference in the parameters except y and b*. In the reliability test result using the SCDA system and the SPEC, the SCDA system was highly reliabile in terms of the CV value in all color model parameters. Conclusions: The color distribution analysis method using the SCDA system has revealed an aspect that the existent method of medical research has not shown, and is considered to be more reliable than other methods. This method can provide better study findings because it can be applied to other fields in addition to the medical science field and the ripple effect is thought to be bigger in other science field too.  相似文献   
26.
27.
28.
29.
The purpose of this study was to examine the levels of anxiety of mothers with children in pediatric intensive care units with different types of visitation policies, both structured and individualized Forty subjects were obtained from two children's hospitals A comparative research design was used Data showed that mothers who experienced individualized visitation had significantly lower anxiety scores (p < 005) than mothers who experienced structured visitation Findings also revealed that mothers viewed their child's illness as less severe when individualized visitation was permitted as opposed to structured visitation.  相似文献   
30.
In medical studies with censored data Kaplan and Meier's product limit estimator has frequent use as the estimate of the survival function. Simultaneous confidence intervals for the survival function at various time points constitute a useful addition to the analysis. This study compares several such methods. We consider in a simulation investigation two whole curve confidence bands and four methods based on the Bonferroni inequality. The results show that three Bonferroni-type methods are essentially equivalent, all being better than the other methods when the number of time points is small (3 or 5).  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