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   143341篇
  免费   48704篇
  国内免费   221篇
耳鼻咽喉   2148篇
儿科学   6448篇
妇产科学   2374篇
基础医学   23120篇
口腔科学   7244篇
临床医学   24427篇
内科学   36136篇
皮肤病学   8863篇
神经病学   20151篇
特种医学   3861篇
外科学   20358篇
综合类   466篇
现状与发展   3篇
一般理论   89篇
预防医学   12492篇
眼科学   2320篇
药学   8620篇
  2篇
中国医学   1064篇
肿瘤学   12080篇
  2024年   290篇
  2023年   1803篇
  2022年   1101篇
  2021年   3494篇
  2020年   7072篇
  2019年   12579篇
  2018年   12619篇
  2017年   13704篇
  2016年   14449篇
  2015年   14450篇
  2014年   15124篇
  2013年   16439篇
  2012年   8813篇
  2011年   8894篇
  2010年   11952篇
  2009年   8435篇
  2008年   5918篇
  2007年   4731篇
  2006年   4779篇
  2005年   4233篇
  2004年   4001篇
  2003年   3721篇
  2002年   3476篇
  2001年   1397篇
  2000年   1060篇
  1999年   813篇
  1998年   887篇
  1997年   755篇
  1996年   682篇
  1995年   615篇
  1994年   451篇
  1993年   437篇
  1992年   310篇
  1991年   254篇
  1990年   220篇
  1989年   213篇
  1988年   197篇
  1987年   146篇
  1986年   149篇
  1985年   156篇
  1984年   141篇
  1983年   130篇
  1982年   153篇
  1981年   150篇
  1980年   121篇
  1979年   76篇
  1978年   85篇
  1977年   63篇
  1976年   54篇
  1974年   43篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Abstract:  The risks of developing malignant melanoma (MM) include ultraviolet irradiation and genetic factors. To examine the contribution of rare and common variation within known MM genes in sporadic US MM patients, coding regions of known MM susceptibility genes [cyclin-dependent kinase inhibitor 2A ( CDKN2A ), cyclin-dependent kinase 4, melanocortin 1 receptor ( MC1R ) and tyrosinase ( TYR )] were resequenced in 109–135 MM cases. The significance of variants was examined by comparing their frequencies in 390 cancer-free controls. Potential deleterious mutations in CDKN2A were found in two patients and two others had variants of unknown significance. Cases were more likely than controls to harbour the MC1R 'R' variants known or predicted to alter its function ( P  = 0.002), particularly the R160W variant ( P  = 0.0035). The associated TYR R402Q variant (rs1126809*A) was found in 29% of cases, similar to what has been described previously. One MM patient with a family history of MM, who had developed other skin cancers, was homozygous for a novel TYR variant (P406L) of unknown significance. Hence, rare variants in TYR may be important risk factors for skin cancer.  相似文献   
42.
43.
44.
45.
Ganoderma sinensis has been used widely in Oriental countries for the prevention and treatment of various diseases including cancer. Previous studies have shown that the lipid extract from Ganoderma exhibits direct cytotoxicity against tumor cells. Here, it is reported that the lipid extract from germinating G. sinensis spores, at lower concentrations that have no direct tumoricidal activity, induce potent antitumor immune responses in human monocytes/macrophages. Upon stimulation with the lipid extract, monocytes/macrophages exhibited markedly increased production of proinflammatory cytokines and surface expression of costimulatory molecules. Conditioned medium from stimulated cells effectively suppressed the growth of tumor cells. Apparently, the lipid extract triggered macrophage activation via a mechanism different from that associated with LPS. Moreover, it was observed that the lipid extract could partially re‐establish the antitumor activity of the immunosuppressive tumor‐associated macrophages. These results indicated that in addition to its direct tumoricidal activity, the lipid extract from G. sinensis spores could exert antitumor activity by stimulating the activation of human monocytes/macrophages. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
46.
47.
48.
The first‐order kernel analysis in multifocal electroretinogram (mfERG) using low contrast stimulation is suggested as a way to detect the inner retinal responses in animal studies. In this case report, this protocol is applied to human patients with glaucoma to demonstrate the possibility of using mfERG as a tool to detect glaucomatous damage. Two patients with glaucoma were recruited and had mfERG measurements with the 103‐scaled hexagonal stimulus pattern at low (50 per cent) contrast. Their responses were analysed and compared with those from normal subjects with the mfERG measured under the same condition. In the normal subjects, there were obvious oscillatory components on the ascending and descending limbs of the first‐order kernel response to 50 per cent contrast. In the glaucomatous patients, the oscillatory component on the descending limb was obviously diminished. In addition, this component was significantly diminished in the quadrant with a glaucomatous visual field defect. This suggests that the low‐contrast stimulation condition in mERG measurement may provide a good way to detect glaucomatous damage and this may help in clinical diagnosis of glaucoma.  相似文献   
49.
The mechanism of release from sustained-release adinazolam mesylate tablets was assessed by the Higuchi equation and by analysis of drug release profiles through 60% released using the Peppas equation. Computed values of the diffusional exponent, n, ranged from 0.59 to 0.66. Values of n in this range are consistent with a mixed mechanism of release, with diffusion of drug through the hydrated polymer matrix and relaxation of this matrix being the principal processes controlling release. The rate of in vitro drug release was increased for half tablets relative to whole tablets and is attributed to an increase in the surface to volume ratio of half tablets of about 16%. This increase in surface-to-volume ratio of half tablets was reflected by an increase in the constant, k, from the Peppas equation of 20–23% and by an increase in the slope of Higuchi plots of 12–18% for four lots of tablets. In vivo/in vitro relationships from two bioavailability studies were thoroughly evaluated. Using either a linear or a quadratic relationship, an in vivo/in vitro correlation exists for sustained-release adinazolam mesylate tablets.  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