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   44篇
  免费   2篇
  2018年   1篇
  2017年   1篇
  2016年   1篇
  2015年   2篇
  2014年   2篇
  2013年   3篇
  2012年   2篇
  2011年   3篇
  2009年   2篇
  2008年   1篇
  2006年   1篇
  2003年   1篇
  2002年   1篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
  1987年   2篇
  1985年   1篇
  1984年   1篇
  1980年   1篇
  1978年   1篇
  1977年   4篇
  1975年   2篇
  1974年   1篇
  1972年   2篇
  1971年   2篇
排序方式: 共有46条查询结果,搜索用时 15 毫秒
11.
The phytotoxic effects of lead (Pb) on seed germinability, seedling growth, photosynthetic performance, and nutrient accumulation (K(+) and Cu(2+)) in two maize genotypes (EV-1098 and EV-77) treated with varying levels of PbSO(4) (0.01, 0.1, and 1.0 mg L(-1)) were appraised in this study. In the seed germination experiment, lead stress significantly reduced seed germination percentage and index, plumule and radicle lengths as well as fresh and dry weights in both genotypes. In the second experiment, lengths and fresh and dry weights of shoots and roots decreased due to Pb in both genotypes with increase in plant age. Higher Pb levels also decreased photosynthetic rate (A), water use efficiency (A/E), and intrinsic water use efficiency (A/g(s)), but increased transpiration rate (E) and C(i)/C(a) ratio as a result of increase in stomatal conductance (g(s)). The concentrations of K(+) and Cu(2+) decreased in root, stem, and leaves of both genotypes, which could be a direct consequence of multifold increase in Pb concentration in these tissues. Overall, cv. EV-1098 had better Pb tolerance potential than EV-77 because the former genotype showed less reduction in seed germinability parameters, photosynthetic performance, and K(+) and Cu(2+) accumulation in shoot and root under lead stress.  相似文献   
12.
利用原位杂交的方法检测KGFmRNA在正常喉粘膜上皮(N)、慢性非特异性炎症(IF)、不典型增生(DYS)及鳞癌(SCC)中的转录水平,探讨KGF在喉粘膜良性及恶性病变中的分布和可能的作用。结果表明,KGFmRNA不仅在间质中的成纤维细胞中表达,少量的炎细胞及血管内皮细胞中亦表达,而且从N、IF、DYS到SCC、KGFmRNA转录水平逐渐增强;上皮细胞及肿瘤性上皮细胞不表达KGFmRNA,KGFmRNA在分化差的SCC周围间质中表达较分化好的SCC周围间质增多。结论:KGF在上皮与间充质细胞的交互作用中发挥着重要的作用,对维持喉粘膜正常结构、代谢及喉癌的发生发展具有重要意义。  相似文献   
13.
14.
15.
Phylogenetic reconstruction of vertebrate Hox cluster duplications   总被引:8,自引:2,他引:6  
In vertebrates and the cephalochordate, amphioxus, the closest vertebrate relative, Hox genes are linked in a single cluster. Accompanying the emergence of higher vertebrates, the Hox gene cluster duplicated in either a single step or multiple steps, resulting in the four-cluster state present in teleosts and tetrapods. Mammalian Hox clusters (designated A, B, C, and D) extend over 100 kb and are located on four different chromosomes. Reconstructing the history of the duplications and its relation to vertebrate evolution has been problematic due to the lack of alignable sequence information. In this study, the problem was approached by conducting a statistical analysis of sequences from the fibrillar-type collagens (I, II, III, and IV), genes closely linked to each Hox cluster which likely share the same duplication history as the Hox genes. We find statistical support for the hypothesis that the cluster duplication occurred as multiple distinct events and that the four-cluster situation arose by a three- step sequential process.   相似文献   
16.
17.
18.
19.
20.
Genistein, a phytoestrogen found in soybeans, is a powerful antioxidant. We evaluated the effects of genistein supplementation on performance, carcass characteristics, levels of malondialdehyde (MDA), homocysteine, vitamins C, E, A in Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature of 34°C. Two hundred and forty Japanese quails (10 d old) were randomly assigned to eight treatment groups consisting of 10 replicates of three birds. The birds were kept in an environmental controlled room either for 24 h/d at 22°C with (thermoneutral, TN groups) or for 16 h/d at 22°C and for 8 h/d (09.00 am to 05.00 pm) at 34°C (heat stress, HS groups). Birds were fed either a basal (control) diet (TN and HS) or the basal diet supplemented with 200, 400 or 800 mg of genistein per kg of diet. Heat exposure decreased birds' performance when basal diet was fed. Increase in feed intake and body weight, and improvement of feed efficiency and carcass traits were found in genistein-supplemented quails reared under heat stress conditions. Growth rate and feed efficiency improved in quails reared under thermo-neutral conditions as well. Concentration of serum vitamins C, E, and A increased in supplemented birds reared at high temperature, while non-significant changes occurred in TN groups. With genistein supplementation homocysteine levels in serum and MDA levels in serum and liver decreased in all birds of both TN and HS groups. Effects of genistein were relatively greater in heat-stressed quails than in quails kept under thermo-neutral conditions. Results of the present study suggest that supplementation with genistein can be considered to be protective by reducing the negative effects of oxidative stress induced by heat stress in quail.  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