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   1514篇
  免费   179篇
  国内免费   28篇
耳鼻咽喉   6篇
儿科学   143篇
妇产科学   24篇
基础医学   205篇
口腔科学   90篇
临床医学   157篇
内科学   287篇
皮肤病学   49篇
神经病学   33篇
特种医学   173篇
外科学   228篇
综合类   38篇
预防医学   94篇
眼科学   40篇
药学   54篇
中国医学   2篇
肿瘤学   98篇
  2023年   14篇
  2022年   10篇
  2021年   15篇
  2020年   14篇
  2019年   8篇
  2018年   44篇
  2017年   46篇
  2016年   41篇
  2015年   60篇
  2014年   76篇
  2013年   107篇
  2012年   50篇
  2011年   30篇
  2010年   78篇
  2009年   91篇
  2008年   30篇
  2007年   50篇
  2006年   48篇
  2005年   26篇
  2004年   31篇
  2003年   13篇
  2002年   19篇
  2001年   15篇
  2000年   10篇
  1999年   24篇
  1998年   101篇
  1997年   88篇
  1996年   98篇
  1995年   63篇
  1994年   74篇
  1993年   39篇
  1992年   16篇
  1991年   21篇
  1990年   13篇
  1989年   31篇
  1988年   29篇
  1987年   28篇
  1986年   26篇
  1985年   24篇
  1984年   12篇
  1983年   9篇
  1982年   20篇
  1981年   15篇
  1980年   16篇
  1979年   6篇
  1978年   6篇
  1977年   9篇
  1976年   13篇
  1975年   9篇
  1966年   1篇
排序方式: 共有1721条查询结果,搜索用时 0 毫秒
61.
62.
In recent reports we described novel hybridization patterns (HP) corresponding to 22 potentially new HLA-B locus alleles in a panel of 547 subjects studied by PCR-SSOP. Three of them correspond to new subtypes of B35. To confirm the hybridization results we have isolated DNA from PBL and performed PCR, DNA cloning and nucleotide sequencing. One of the alleles, locally called B-3505v was found in three individuals: two Hispanic, one Caucasoid. It differs from B*3505 by 3 nucleotide substitutions that lead to changes in residues 94 (Ile > Thr), 95 (Ile > Leu) and 103 (Val > Leu). B-3505v differs from B*3501 in residues 97 and 103. Another allele called B-3508v, was found in 7 individuals, (6 of 122 Toba Indians, 1 of 18 Pilaga Indians). It differs from B*3509 in two silent nucleotide substitutions (codons 135 and 138) and in one substitution in residue 156 (Arg > Leu). The new allele has a hybrid sequence between B* 3508 and B*4801. A third subtype, locally called B-3504v, observed in two Hispanic individuals, is identical to B*3512. B*3512 differs from B*3504 by 3 nucleotides and one amino acid. Substitutions in residue 95 contribute to the structure of specificity pocket F, 97 to C and E, and 156 to pockets D and E. Therefore it is possible that some of the new alleles may have different peptide binding profiles. Since differences in residue 156 have been shown to affect allorecognition and mediate GvHD, identification of such variants may have important implications in transplantation and perhaps in studies of immune responses to peptides and pathogens.  相似文献   
63.
64.
The inactive X (Xi) differs from its active homologue (Xa) in a number of ways, including increased methylation of CpG islands, replication late in S phase, underacetylation of histone H4 and association with XIST RNA. Global changes in DNA methylation occur relatively late in development, but the other properties all change during or shortly after the establishment of Xi and may play a role in the mechanism by which an inactive chromatin conformation spreads across most of the chromosome. In the present report, we use two human X;autosome translocation chromosomes to study the spreading of inactive X chromatin across X;autosome boundaries. In one of these chromosomes, t(X;6), Xp distal to p11.2 is replaced by 6p21.1-6pter and, in the other, ins(X;16), a small fragment derived from 16p13 is inserted into the distal third of Xq. In lymphoid cells from patients carrying these translocations in an unbalanced form, Xi was shown by HUMARA assay to be derived exclusively [t(X:6)] or predominantly [ins (X;16)] from the derived X chromosome. We used a combination of immunolabelling and RNA/DNA fluorescence in situ hybridization to define the distribution of XIST RNA, deacetylated H4 and late-replicating DNA across the two derived X chromosomes in inactive form. Within the limits of the cytogenetic techniques employed, the results show complete coincidence of these three parameters, with all three being excluded from the autosomal component of the derived X chromosome.   相似文献   
65.

Background  

Despite large-scale investments in mental health care in the community since the 1990 s, a trend towards reinstitutionalization has been visible since 2002. Since many mental health care providers regard this as an undesirable trend, the question arises: In the coming 5 years, what types of residence should be organized for people with mental health problems? The purpose of this article is to provide mental health care providers, public housing corporations, and local government with guidelines for planning organizational strategy concerning types of residence for people with mental health problems.  相似文献   
66.
Autosomal recessive nonsyndromic hearing impairment (ARNSHI) segregating in three unrelated, large consanguineous Pakistani families (PKDF528, PKDF859 and PKDF326) is linked to markers on chromosome 12q14.2-q15. This novel locus is designated DFNB74 . Maximum two-point limit of detection (LOD) scores of 5.6, 5.7 and 2.6 were estimated for markers D 12 S 313, D 12 S 83 and D 12 S 75 at θ = 0 for recessive deafness segregating in these three families. Haplotype analyses identified a critical linkage interval of 5.35 cM (5.36 Mb) defined by D 12 S 329 at 74.58 cM and D 12 S 313 at 79.93 cM. DFNB74 is the second ARNSHI locus mapped to chromosome 12, but the physical intervals do not overlap with one another. A locus contributing to the early onset, rapidly progressing hearing loss of A/J mice ( ahl4 , age-related hearing loss 4) was reported to map to chromosome 10 in a region of conserved synteny to DFNB74 , suggesting that ahl4 and DFNB74 may be due to mutations of the same gene in these two species.  相似文献   
67.
68.
69.
70.
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