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   211839篇
  免费   15167篇
  国内免费   2567篇
耳鼻咽喉   2936篇
儿科学   4058篇
妇产科学   4667篇
基础医学   30833篇
口腔科学   4208篇
临床医学   20772篇
内科学   39645篇
皮肤病学   5391篇
神经病学   16046篇
特种医学   10261篇
外国民族医学   3篇
外科学   27588篇
综合类   5760篇
现状与发展   15篇
一般理论   96篇
预防医学   13954篇
眼科学   5661篇
药学   18408篇
  23篇
中国医学   3078篇
肿瘤学   16170篇
  2023年   1509篇
  2022年   3957篇
  2021年   6570篇
  2020年   3740篇
  2019年   4908篇
  2018年   5808篇
  2017年   4431篇
  2016年   5502篇
  2015年   7408篇
  2014年   9094篇
  2013年   10911篇
  2012年   16274篇
  2011年   15904篇
  2010年   9643篇
  2009年   8083篇
  2008年   11851篇
  2007年   11581篇
  2006年   10644篇
  2005年   10119篇
  2004年   8915篇
  2003年   7857篇
  2002年   6925篇
  2001年   5561篇
  2000年   5113篇
  1999年   4169篇
  1998年   1742篇
  1997年   1383篇
  1996年   1269篇
  1995年   1172篇
  1994年   1006篇
  1993年   920篇
  1992年   2181篇
  1991年   2188篇
  1990年   1875篇
  1989年   1815篇
  1988年   1731篇
  1987年   1605篇
  1986年   1496篇
  1985年   1378篇
  1984年   1035篇
  1983年   885篇
  1982年   646篇
  1981年   596篇
  1980年   537篇
  1979年   811篇
  1978年   660篇
  1977年   566篇
  1976年   498篇
  1974年   559篇
  1973年   546篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
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   
43.
Many studies have recently reported on laparoscopic liver resection, although its development has been slow compared to laparoscopy in other fields. The indications for the location of laparoscopic liver resection have previously been limited to easily accessible lesions. Performing laparoscopic liver resection in the posterior and superior parts of the liver has been considered difficult due to inadequate exposure, the poor operative field and the difficulty with parenchymal dissection. Flexible endoscopy, high definition imaging and various kinds of equipment for parenchymal transection have been introduced for clinical use. In addition, much experience with this procedure has been accumulated at many centers. Accordingly, there are an increasing number of reports on laparoscopic liver resection in difficult locations. At our institution, the location of the tumor is no longer a limitation to laparoscopic liver resection. However, for safer laparoscopic liver resection, the patient positioning and trocar placement should be individualized according to the tumor location. The type of resection also may depend on the remaining liver’s functional capacity. We describe here the technical considerations for performing laparoscopic liver resection, including the technical considerations for performing laparoscopic liver resection for lesions located in the postero-superior segments of the liver.  相似文献   
44.
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   
45.
46.
47.
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   
48.
49.
目的 探讨中药大陷胸汤高位保留灌肠对流行性出血热(EHF)急性肾衰的治疗作用。方法 将60例EHF急性肾衰患者随机分为对照组与治疗组各30例,对照组予以常规治疗,治疗组在常规治疗的基础上加用大陷胸汤高位保留灌肠,观察两组患者治疗前后的疗效。结果 治疗组治愈23例,好转6例,无效1例,总有效率96.7%;对照组治愈17例,好转7例,无效6例,总有效率80.0%;两组疗效比较,有显著差异性p〈0.05(x^2=4.630)。结论 大陷胸汤高位保留灌肠治疗EHF急性肾衰疗效显著,且简便、安全、经济、病人乐于接受等优点。  相似文献   
50.
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