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   171837篇
  免费   11589篇
  国内免费   4720篇
耳鼻咽喉   2327篇
儿科学   2392篇
妇产科学   2490篇
基础医学   25630篇
口腔科学   4073篇
临床医学   17697篇
内科学   29397篇
皮肤病学   4477篇
神经病学   12657篇
特种医学   8959篇
外国民族医学   20篇
外科学   21271篇
综合类   8256篇
现状与发展   18篇
一般理论   33篇
预防医学   9743篇
眼科学   4387篇
药学   15981篇
  28篇
中国医学   4245篇
肿瘤学   14065篇
  2024年   229篇
  2023年   1584篇
  2022年   4524篇
  2021年   6643篇
  2020年   3826篇
  2019年   4406篇
  2018年   5249篇
  2017年   4447篇
  2016年   5237篇
  2015年   7414篇
  2014年   8957篇
  2013年   9670篇
  2012年   14398篇
  2011年   14234篇
  2010年   8256篇
  2009年   7026篇
  2008年   9742篇
  2007年   9443篇
  2006年   8716篇
  2005年   8033篇
  2004年   6901篇
  2003年   6350篇
  2002年   5530篇
  2001年   4412篇
  2000年   4003篇
  1999年   3441篇
  1998年   1781篇
  1997年   1468篇
  1996年   1141篇
  1995年   1028篇
  1994年   898篇
  1993年   590篇
  1992年   1093篇
  1991年   983篇
  1990年   909篇
  1989年   775篇
  1988年   675篇
  1987年   641篇
  1986年   479篇
  1985年   459篇
  1984年   337篇
  1983年   222篇
  1982年   150篇
  1981年   183篇
  1980年   142篇
  1979年   228篇
  1978年   164篇
  1976年   132篇
  1975年   121篇
  1974年   139篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
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   
22.
23.
Beta-adrenergic receptor density on T cells from healthy humans is greatest on suppressor cells (CD8+, CD28-) and the effect of catecholamines, secreted by the sympathetic nervous system, predominates on this subset. The sympathetic skin response, a measure of sympathetic nervous system function, is absent in most patients with chronic progressive multiple sclerosis (MS). We measured beta-adrenergic receptor density on suppressor cells, cytotoxic cells, and monocytes from patients with chronic progressive MS and healthy control subjects. Control receptor density on suppressor cells was 2.8 +/- 0.3 fmol/10(6) cells versus a density of 5.1 +/- 0.7 fmol/10(6) cells for patients. Cytotoxic cell (CD8+, CD28+) receptor density was 1.4 +/- 0.4 fmol/10(6) cells in control subjects and 0.9 +/- 0.3 fmol/10(6) cells in the patients. Monocytes displayed beta-adrenergic receptor densities of 2.6 +/- 0.4 fmol/10(6) cells in normal individuals and 2.7 +/- 0.4 fmol/10(6) cells in the patient group. CD8 lymphocyte beta-adrenergic receptor densities in patients with relapsing-remitting and those with stable MS were not different from control values, yet were significantly less than the values for patients with chronic progressive MS. We find that mononuclear cells from healthy control subjects and patients with chronic progressive MS proliferate in response to 200 units/ml of recombinant human interleukin-2 (IL-2) similarly. However, IL-2 treatment increased beta-adrenergic receptor density on normal mononuclear cells, but failed to increase it on mononuclear cells from patients with chronic progressive MS.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
24.
25.
26.
27.
28.
29.
Diseases like rotavirus afflict both upper- and lower-income countries, but most serious illnesses and deaths occur among the latter. It is a vital public health issue that vaccines for these types of global diseases can recover research and development (R&D) costs from high-priced markets quickly so that manufacturers can offer affordable prices to lower-income nations. Cost recovery depends on how high R&D costs are, and this study attempts to replace high, unverified estimates with lower, more verifiable estimates for two new vaccines, RotaTeq (Merck) and Rotarix (GlaxoSmithKline or GSK), based on detailed searches of public information and follow-up interviews with senior informants. We also offer a new perspective on “cost of capital” as a claim for recovery from public bodies. Our estimates suggest that companies can recover all fixed costs quickly from affluent markets and thus can offer these vaccines to lower-income countries at prices they can afford. Better vaccines are a shared project between companies and public health agencies; greater transparency and consistency in reporting of R&D costs is needed so that fair prices can be established.  相似文献   
30.
Intractable tinnitus can lead to serious consequences. Study evidence indicates that the central nervous system is involved in generation and maintenance of chronic tinnitus and that tinnitus and other neurologic symptoms such as chronic pain may share similar mechanisms. Brain ablation and stimulation are used to treat chronic pain with success. Recent studies showed that ablation and stimulation in non-auditory areas resulted in tinnitus improvement. Deep brain stimulation (DBS) may be an alternative treatment for intractable tinnitus and deserves further study.  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