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   199篇
  免费   17篇
  国内免费   6篇
  2023年   2篇
  2022年   4篇
  2020年   3篇
  2019年   3篇
  2018年   3篇
  2017年   7篇
  2016年   6篇
  2015年   8篇
  2014年   12篇
  2013年   15篇
  2012年   8篇
  2011年   7篇
  2010年   5篇
  2009年   9篇
  2008年   9篇
  2007年   7篇
  2006年   9篇
  2005年   9篇
  2004年   4篇
  2003年   8篇
  2002年   4篇
  2001年   7篇
  2000年   7篇
  1999年   14篇
  1997年   1篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1992年   9篇
  1991年   1篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1987年   4篇
  1986年   2篇
  1985年   2篇
  1984年   3篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1978年   2篇
  1977年   1篇
  1974年   1篇
  1973年   4篇
  1972年   1篇
  1970年   2篇
  1968年   1篇
  1965年   2篇
  1916年   1篇
排序方式: 共有222条查询结果,搜索用时 15 毫秒
141.
Analysis of TCR of a series of CD4-8- (double negative; DN) alpha beta T cell lines induced with IL-3 revealed that their V gene usage was biased for V alpha 4 and V beta 2. This has been confirmed in the primary short-term cultures. Thus, IL-3 induced the generation of DN alpha beta T cells with predominant V beta 2 gene expression from the CD4+/CD8+ T cell-depleted spleen or bone marrow (BM) cells of both normal and nude BALB/c mice within 10 days. It was further indicated that the V beta 2+ beta-chain genes contained few junctional N regions in both IL-3-induced primary DN alpha beta T cells and continuous lines. Search for the in vivo counterpart of in vitro IL-3-induced DN alpha beta T cells revealed that BM, but not spleens, of normal BALB/c and B6 mice did contain a significant proportion of DN alpha beta T cells, and that the majority of them expressed V beta 2+ beta-chain genes with few junctional N regions. The presence of V beta 2+ DN alpha beta T cells was similarly observed in the BM of BALB/c nude mice, but their proportion varied markedly among various strains of mice, which was not linked to H-2 haplotypes. The results indicated that V beta 2+ DN alpha beta T cells in the BM represented one of the thymus-independent T cell populations, whose development was under the major histocompatibility Ag complex-unlinked genetic control. TCR of these T cells were shown to be functional as judged by the proliferative response to anti-V beta 2 antibody. Taken together, present results suggested that IL-3 could induce differentiation and/or proliferation of DN alpha beta T cells with uniquely limited repertoire, which existed preferentially in BM in vivo, and implied the possible involvement of extrathymic endogenous ligands as a positive selection force.  相似文献   
142.
蚊微蛛属Solenysa是一类小型微蛛,以往该属仅记述一种,Solenysa mellottei Simon,1984,分布于朝鲜和日本,我国尚系首次记述该属蜘蛛。本属最典型的特征为:体微小,腹柄发达而使蜘体呈蚁状,Ⅰ—Ⅳ均仅有一根背刺。本文所记述的二种蜘蛛均系土壤蜘蛛。文内所用单位均为mm。全部模式标本均保存于中国科学院动物研究所。  相似文献   
143.
Integration of bovine leukemia virus (BLV) in the genomes of infected cells was investigated in cattle with enzootic bovine leukosis (EBL) and sporadic bovine leukosis (SBL). Southern blot hybridization of BLV cDNA to Eco RI and Xba I restriction fragments of EBL tumor DNAs revealed that: 1) one to four or more copies of proviral DNA were integrated per genome; 2) the restriction pattern of the integrated proviral DNA was the same in two or three different tumors from the same animals; and 3) different patterns were observed among tumors from four different animals. These findings suggest the monoclonal origin of different tumors in an individual animal and the existence of multiple chromosomal integration sites of BLV provirus. DNAs from several SBL tumors were also analyzed with the same restriction enzymes, but with both representative and cDNA3'-enriched's of BLV RNA. No hybridization bands reactive with representative BLV cDNA could be detected, while several bands appeared to hybridize with cDNA3'-enriched.  相似文献   
144.
济南市社会经济发展与儿童少年生长的长期变化   总被引:6,自引:2,他引:4  
本文分析了1956-1995年济南市7-18岁儿童少年生长发育的变化趋势。39年间,男女生身高平均增长值分别为10.83cm的9.47cm,平均每10年增长2.768cm和2.43cm;男一体重增长值分别为9.19kg和5.12kg,平均每10年增长2.36kg和1.31kg。将不同年代人均工业总产值作对数转换后发现,与各年龄儿童少年身高、体重的发育水平呈明显的直线正相关,不同年代人均工业总产值的  相似文献   
145.
应用流式细胞术(FCM)对处于稳定生长阶段的念珠菌属(Candida)的7种8株念珠菌进行了DNA总含量的流式细胞(FCM)分析。这8株念珠菌是:白念珠菌(C.albicans)2株,热带念珠菌(C.tropicalis),克柔念珠菌(C.krusei),近平滑念珠菌(C.parapsiolosis),乳酒念珠菌(C.kefyr),白念珠菌星形变种(C.stellatoidea),即血清B型白念珠菌,季也蒙念珠菌(C.guilliermondii)各一株。应用EB一步插入法染色,用鸡红细胞(CRBC)作为内参标准进行DNA总含量测定。分析结果表明:稳定生长阶段的组方图上,大多数念珠菌细胞处于DNA合成周期的G_0/G_1期;DNA总含量有明显的种间和种内差异。  相似文献   
146.
147.
148.
Resistin, secreted from adipocytes, causes insulin resistance and diabetes in rodents. To determine the relation between serum resistin and diabetic microangiopathies in humans, we analyzed 238 Japanese T2DM subjects. Mean serum resistin was higher in subjects with either advanced retinopathy (preproliferative or proliferative) (P=0.0130), advanced nephropathy (stage III or IV) (P=0.0151), or neuropathy (P=0.0013). Simple regression analysis showed that serum resistin was positively correlated with retinopathy stage (P=0.0212), nephropathy stage (P=0.0052), and neuropathy (P=0.0013). Multiple regression analysis adjusted for age, gender, and BMI, revealed that serum resistin was correlated with retinopathy stage (P=0.0144), nephropathy stage (P=0.0111), and neuropathy (P=0.0053). Serum resistin was positively correlated with the number of advanced microangiopathies, independent of age, gender, BMI, and either the duration of T2DM (P=0.0318) or serum creatinine (P=0.0092). Therefore, serum resistin was positively correlated with the severity of microangiopathies in T2DM.  相似文献   
149.
Lead optimization of CH4892280 (4), an androgen receptor (AR) pure antagonist, was investigated. Compounds 6 and 7, which have a carboxylic acid at the end of the side chain at the position 7alpha of dihydrotestosterone (DHT), showed partial agonistic activities in reporter gene assay (RGA). Conversion of the steroidal core structure to 17alpha-methyltestosterone gave compound 14, which showed weak pure antagonistic activity. Optimization of the side chain by the insertion of a phenyl ring led to compounds 22 and 28-30, which showed pure antagonistic activities at submicromolar concentrations. The structure-activity relationships were clarified.  相似文献   
150.
The pathological effects of exposure to an electromagnetic field (EMF) during childhood and adolescence may be greater than those from exposure during adulthood. We investigated possible pathological changes in the cerebellum of adolescent rats exposed to 900 MHz EMF daily for 25 days. We used three groups of six 21-day-old male rats as follows: unexposed control group (Non-EG), sham-exposed group (Sham-EG) and an EMF-exposed group (EMF-EG). EMF-EG rats were exposed to EMF in an EMF cage for 1 h daily from postnatal days 21 through 46. Sham-EG rats were placed in the EMF cage for 1 h daily, but were not subjected to EMF. No procedures were performed on the Non-EG rats. The cerebellums of all animals were removed on postnatal day 47, sectioned and stained with cresyl violet for histopathological and stereological analyses. We found significantly fewer Purkinje cells in the EMF-EG group than in the Non-EG and Sham-EG groups. Histopathological evaluation revealed alteration of normal Purkinje cell arrangement and pathological changes including intense staining of neuron cytoplasm in the EMF-EG group. We found that exposure to continuous 900 MHz EMF for 1 h/day during adolescence can disrupt cerebellar morphology and reduce the number of Purkinje cells in adolescent rats.  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