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   6488篇
  免费   389篇
  国内免费   16篇
耳鼻咽喉   43篇
儿科学   130篇
妇产科学   112篇
基础医学   837篇
口腔科学   443篇
临床医学   575篇
内科学   1385篇
皮肤病学   133篇
神经病学   576篇
特种医学   249篇
外科学   931篇
综合类   32篇
一般理论   2篇
预防医学   487篇
眼科学   88篇
药学   498篇
中国医学   19篇
肿瘤学   353篇
  2023年   35篇
  2022年   47篇
  2021年   93篇
  2020年   74篇
  2019年   89篇
  2018年   153篇
  2017年   129篇
  2016年   141篇
  2015年   150篇
  2014年   169篇
  2013年   302篇
  2012年   436篇
  2011年   411篇
  2010年   275篇
  2009年   251篇
  2008年   375篇
  2007年   385篇
  2006年   391篇
  2005年   405篇
  2004年   398篇
  2003年   359篇
  2002年   348篇
  2001年   89篇
  2000年   65篇
  1999年   96篇
  1998年   85篇
  1997年   59篇
  1996年   56篇
  1995年   57篇
  1994年   43篇
  1993年   40篇
  1992年   49篇
  1991年   60篇
  1990年   52篇
  1989年   57篇
  1988年   48篇
  1987年   52篇
  1986年   44篇
  1985年   64篇
  1984年   50篇
  1983年   31篇
  1982年   42篇
  1981年   33篇
  1980年   20篇
  1979年   25篇
  1978年   28篇
  1977年   31篇
  1976年   23篇
  1975年   19篇
  1974年   23篇
排序方式: 共有6893条查询结果,搜索用时 15 毫秒
41.
The localization of the A-rafcellular oncogene on the mouse X chromosome has been determined using Xbal-restricted DNAs prepared from progeny of an interspecies backcross between the B6.CBA.R1 and the Spe/Pas mouse strains. This localization to the proximal part of the mouse X chromosome has been confirmed by the use of somatic cell hybrids, carrying partially deleted X chromosomes and suggests that the A-raf oncogene localizes to a region lying some 10–17 centimorgans proximal to the hypoxanthine phosphoribosyltransferase (Hprt) gene between the locus DXPas4and the locus DXPas7defined by the cross-reacting human X chromosome-specific probe DXS32 (M2C). This localization on the mouse X chromosome is compatible with the presence of the A-rafoncogene on the short arm of the human X chromosome between the centromere and Xp21.  相似文献   
42.
Genome of the European elk papillomavirus (EEPV)   总被引:1,自引:0,他引:1  
The genome of the European elk papillomavirus (EEPV) was found to be 8,095 base pairs (bp) long and its genetic organization was similar to that of other papillomaviruses. Ten open reading frames (ORFs), designated E1-E7 and L1-L3, were identified in the genome, all located on one strand. The presence of the L3 ORF is rare among the papillomaviruses and to date has only been identified in the genomes of EEPV, the deer papillomavirus (DPV) and the Cottontail papillomavirus (CRPV). The ORF is well conserved beteeen DPV and EEPV with regard to both length and sequence. Potential promoter regions were identified at the 5-end of the E6 ORF, at the 3-end of the E1 ORF and downstream of the L1 ORF. Furthermore, two potential polyadenylation signals were found, one located in the long control region (LCR), downstream of the L1 ORF, and another preceding the L2 ORF. The EEVP genome is closely related to the genome of the DPV, the most highly conserved regions being ORFs E1 (70%), E5 (69%), and L1 (74%).  相似文献   
43.
ABSTRACT

This study examined if children (Mage = 14.60) with Mild Intellectual Disabilities (MID) display weaknesses in number processing and verbal working memory. An age-matched and mental age-matched (MA, Mage = 6.17) design extended by a group of 9–10-year-olds, and a group of 11–12-year-olds were used. The MID children’s working memory was equal to the MA group but poorer than the other groups. On number tasks, the MID group was faster than the MA group but slower than the other groups. All groups obtained equal Weber fraction scores and distance effects on the number comparison tasks. The MID group performed subitizing and counting faster than the MA group, but slower than the 11–12-year-olds. The results demonstrate that number processing and working memory in children with MID is characterized by a developmental delay, not a deficit. Their main problem is to access the quantitative meaning of Arabic numerals. The development of different types of cognitive abilities is differently affected by educational experience and intellectual ability. The innate number system appears to be unaffected by intellectual capacity or educational experience, while the innate working memory ability is affected by intellectual capacity but not by educational experience. Culturally acquired symbolic number abilities are strongly affected by educational experience.  相似文献   
44.
45.
46.
47.
Gamma-Interferon is Produced by CD3+ and CD3- Lymphocytes   总被引:7,自引:0,他引:7  
  相似文献   
48.
GAP-43 is normally produced by neurons during developmental growth and axonal regeneration, but it is also expressed in specific regions of the normal adult nervous system. We studied the protein expression of GAP-43 within the conus medullaris portion of the spinal cord in adult male rats. Immunohistochemistry for choline acetyltransferase (ChAT) was first performed to identify specific efferent autonomic and motor nuclei in lumbosacral segments of the spinal cord. Adjacent sections were then processed for GAP-43 immunoreactivity (IR). We show GAP-43 IR in the superficial portion of the dorsal horn, the intermediolateral nucleus, and the dorsal commissural tract. We also demonstrate a differential distribution of GAP-43 IR between different motor nuclei of the conus medullaris. Using densitometry, the most prominent GAP-43 IR was detected in the dorsolateral and dorsomedial motor nuclei, which represent the human Onufs nucleus homologue. Confocal microscopy of double immunofluorescent labeling for ChAT and GAP-43 demonstrate GAP-43 IR in the neuropil of the autonomic and motor nuclei, and many of the GAP-43 IR arbors are in close apposition with the efferent cholinergic neurons. We note that the efferent neurons of both the autonomic and somatic nuclei, which are ultimately responsible for the integrated normal control of the lower urinary tract, bowel and sexual functions, are heavily innervated by GAP-43 enriched projections. We speculate that these functionally related neurons retain a physiological GAP-43-associated synaptic plasticity throughout adult life.  相似文献   
49.
50.
Psyllium is a hydrophilic agent found in many bulk laxative preparations. We report the occurrence of an anaphylactic reaction in a patient after ingestion of a psyllium-containing laxative. IgE mediation of the reaction was suggested by a positive immediate skin test to psyllium, positive passive transfer skin test, lack of skin response during passive transfer with heat treated serum, and an elevated IgE (RAST) to psyllium seed.  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