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   4345篇
  免费   448篇
  国内免费   7篇
  4800篇
  2023年   33篇
  2022年   48篇
  2021年   124篇
  2020年   69篇
  2019年   73篇
  2018年   83篇
  2017年   79篇
  2016年   148篇
  2015年   202篇
  2014年   216篇
  2013年   222篇
  2012年   311篇
  2011年   304篇
  2010年   212篇
  2009年   169篇
  2008年   273篇
  2007年   260篇
  2006年   259篇
  2005年   229篇
  2004年   201篇
  2003年   194篇
  2002年   158篇
  2001年   54篇
  2000年   34篇
  1999年   48篇
  1998年   38篇
  1997年   26篇
  1996年   32篇
  1995年   36篇
  1994年   23篇
  1993年   19篇
  1992年   30篇
  1991年   31篇
  1990年   24篇
  1989年   17篇
  1988年   26篇
  1987年   16篇
  1986年   22篇
  1985年   18篇
  1984年   25篇
  1982年   21篇
  1981年   15篇
  1980年   25篇
  1978年   17篇
  1977年   19篇
  1976年   14篇
  1974年   21篇
  1973年   14篇
  1971年   14篇
  1970年   11篇
排序方式: 共有4800条查询结果,搜索用时 0 毫秒
1.
2.
3.
Thirty cases of intraspinal neoplasms occurring during the first two decades of life are reviewed. Histologic examination showed 13 of these to be astrocytomas, 6 neuroblastomas, 5 sarcomas, 3 ependymomas, 2 neurofibromas and 1 a schwannoma. Orthopedic deformities developed or worsened in 60 percent of patients surviving longer than a year after diagnosis. In five patients some form of endocrine deficiency developed after irradiation. For treatment of radiosensitive extradural malignant lesions, biopsy followed by irradiation is advocated.  相似文献   
4.
A gene encoding the endogenous superantigen Mlsc, which deletes Tcrb-V3+ T cells in the NOD inbred mouse strain, was found to co-segregate with Mtv-3 on chromosome 11. This identifies a fourth gene encoding a deletion ligand for Tcrb-V3+ T cells and extends recently published observations in support of the hypothesis that a number of endogenous superantigens are the products of Mtv proviruses. Address correspondence and offprint requests to : K. Tomonari.  相似文献   
5.
6.
7.
8.
The JY328 clone was identified in a human genomic library using cDNA corresponding to mRNA for HLA-B7 as a probe. The L/328 cell line was established by cotransformation of mouse Ltk cells with the herpes thymidine kinase gene and clone JY328. On Northern blots, RNA from,L/328 strongly hybridized to an HLA class I probe, and an antigen was recognized by an anti-HLA class I framework antibody on the cell surface. A DNA probe corresponding to a segment of intron 7 was developed by comparing the nucleotide sequence of clone JY328 with that of other HLA class I-type genes. Using the radiolabeled probe to screen Southern blots of DNA from families with siblings exhibiting intra-HLA recombinations, a restriction fragment length polymorphism was revealed —a 1.4 kb BstE II band not present in all individuals. A corresponding fragment was apparent in the base sequence of clone JY328. The occurrence of this band on Southern blots established that JY328 maps distinct from and centromeric to the HLA-C locus and near to the HLA-B locus. Antibody absorption studies and cytotoxicity tests indicated that the JY328 gene product was not an HLA-B antigen but that it did specifically absorb CW7-specific antibody. In sum, these results suggest a novel, polymorphic HLA class I gene which expresses a product serologically similar to HLA-Cw7 but which does not map within the corresponding locus.  相似文献   
9.
10.
Antibiotic discs were prepared, using several several batches of papers meeting Food and Drug Administration specifications. The analysis of 1,152 zones of inhibition produced showed no performance differences among these batches. Other discs were prepared using papers of different grades. These produced large differences in performance. It is obvious, therefore, that the use of a specified disc paper is necessary for standardizing the performances of the products of various manufacturers and that reproducible results can be attained with the grade of paper specified.  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