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   72篇
  免费   1篇
  国内免费   3篇
  2019年   1篇
  2018年   1篇
  2016年   3篇
  2015年   6篇
  2014年   1篇
  2013年   1篇
  2011年   3篇
  2010年   3篇
  2009年   5篇
  2008年   2篇
  2007年   2篇
  2006年   2篇
  2005年   6篇
  2004年   1篇
  2003年   3篇
  2002年   2篇
  2001年   3篇
  2000年   1篇
  1997年   3篇
  1996年   3篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1990年   1篇
  1989年   5篇
  1986年   1篇
  1985年   5篇
  1984年   2篇
  1982年   1篇
排序方式: 共有76条查询结果,搜索用时 328 毫秒
51.
We have undertaken comparative studies of the number and phenotypes of erythrocytes in the peripheral blood of red crucian carp (RCC), blunt snout bream (BSB), and their hybrids, including triploids, tetraploids, and pentaploids. The results indicate that the mean nuclear volume of erythrocytes in peripheral blood increases regularly with increasing ploidy. Furthermore, many more mature erythrocytes have a dumbbell nucleus in the peripheral blood of polyploid hybrids compared with their diploid parents. With the increase in ploidy level, the percentage of such erythrocytes increases. The polyploid hybrids also have a large number of erythrocytes with abnormal shapes. For example, round and tear-shaped erythrocytes have been observed in the peripheral blood of polyploid hybrids. Since the erythrocytes in polyploid hybrids with their larger volume and lower specific surface area are unfavorable for the conveyance of oxygen, morphological variations of erythrocytes might improve defective blood circulation. This research was supported by the National Natural Science Fund for Distinguished Young Scholars (grant no. 30725028), the National Natural Science Foundation of China (grant nos. 30330480 and 30571444), National Basic Research Program (grant no. 2007CB109206), and Key Project of Hunan Province (grant no. 2006NK2008).  相似文献   
52.
Daniel J. Rigden 《FEBS letters》2009,583(10):1555-814
The Cry and Cyt classes of insecticidal toxins derived from the sporulating bacterium Bacillus thuringiensis are valuable substitutes for synthetic pesticides in agricultural contexts. Crystal structures and many biochemical data have provided insights into their molecular mechanisms, generally thought to involve oligomerization and pore formation, but have not localised the site on Cyt toxins responsible for selective binding of phospholipids containing unsaturated fatty acids. Here, distant homology between the structure of Cyt toxins and Erwinia virulence factor (Evf) is demonstrated which, along with sequence conservation analysis, allows a putative lipid binding site to be localised in the toxins.  相似文献   
53.
油菜×蔊菜远缘杂交创新油菜种质资源研究   总被引:9,自引:0,他引:9  
本项研究重点是要探讨通过油菜与蔊菜远缘杂交,将蔊菜的某些优良性状转移到栽培油菜中的可行性.结果表明甘蓝型油菜与蔊菜进行远缘杂交有较好的亲和性.而且其杂交后代变异明显,出现了许多碎叶型植株和一些类似白菜型的植株,杂交后代对菌核病有较强的抗性,有许多具有优势的单株.油菜与蔊菜进行远缘杂交对于创新油菜种质资源,培育高产、高抗油菜新品种具有重要意义.  相似文献   
54.
55.
福建大叶蝉科一新记录属及三新种(同翅目:叶蝉总科)   总被引:2,自引:0,他引:2  
本文记述大叶蝉科1中国新记录属──暗大叶蝉属SeasogoniaYoung与1新种──红暗大叶蝉S.sanguineaKuohetzhuo,以及条大叶蝉属AtkinsoniellaDistant2新种──黑背条大叶蝉A.nigridorsumKuohetzhuo与红脉条大叶蝉A.rubrivenosaKuohetZhuo。均采自福建。  相似文献   
56.
鲢的远缘杂交子代和人工三倍体的同工酶表达   总被引:11,自引:1,他引:10  
用聚丙烯酰胺梯度凝胶电泳分析了鲢♀×鳙♂、鲢♀×团头鲂♂的二倍体和异源三倍体杂种,以及同源三倍体鲢及其亲本种的8种蛋白质和同工酶的表型。二倍体杂交子代的基因表达是多样的,这些多样的表达可能与双亲的这些蛋白质和同工酶的表型差异有关。如与二倍体杂交子代相比,鲢×鳙异源三倍体的肌肉蛋白和血清蛋白有效一致的表型,此外在两种异源三倍体中EST和MDH同工酶的表型接近母本,这些结果表明异源三倍体由于增加了一套  相似文献   
57.
Stable cointegrates between incRh-1 octopine (Ach5) and nopaline (C58) Ti-plasmids, present in ten independently isolated Agrobacterium tumefaciens strains, showed identical restriction endonuclease patterns. Each cointegration event had taken place in the common sequence between the T-regions of both Ti-plasmids. This illustrates a high preference for this region when used in the formation of cointegrates. Four crown gall tissues, obtained after transformation of Nicotiana tabacum cells by one of the mutants, were analysed by using Southern blot analysis for their T-DNA structure. The borders of T-DNA frequently appeared to differ from T-DNA borders previously detected in tumour tissues that had been induced by Agrobacterium strain C58 or Ach5. Therefore, it was concluded that possibly a less stringent mechanism exists for the integration into plant DNA of T-DNA, derived from a composite (octopine/nopaline) T-region than for integration of T-DNA from a normal (octopine or nopaline) T-region.Abbreviations Agr sensitivity to agrocin 84 - Ape phage Apl exclusion - Cb resistance to carbenicillin - Occ octopine catabolism - Ocs octopine synthesis - Noc nopaline catabolism - Nos nopaline synthesis - Rec recombination - Tra transfer - Vir virulence  相似文献   
58.
A 5S rRNA gene (5S DNA) from the coniferPinus radiata D. Don has been cloned and characterized at the nucleotide, genomic and chromosomal levels. Sequencing revealed a repeat unit of 524 base pairs which is present in approximately 3000 copies per diploid genome. Two-dimensional gel electrophoresis indicated that these copies are organized in tandem arrays of various length. Using in situ hybridization techniques, the tandem arrays appear to be present on all of the chromosomes. This complexity of chromosomal organization contrasts markedly with the few sites of uniform length found in angiosperm plants such as wheat, pea, and maize.  相似文献   
59.
Anaerobic sludge granules were obtained from laboratory-scale anaerobic bioreactors used to treat pharmaceutical-like (methanol-, acetone- and propanol-contaminated) wastewater under low-temperature conditions (15 degrees C). The microbial diversity and diversity changes of the sludge samples were ascertained by applying 16S rRNA gene cloning and terminal restriction fragment length polymorphism (TRFLP) analyses, respectively, and using sludge samples from the inoculum, throughout and at the conclusion of the bioreactor trial. Data from genetic fingerprinting correlated well with those from physiological activity assays of the reactor biomass. Specifically, for example, TRFLP profiles indicated the dominance of hydrogenotrophic methanogens within the archaeal community, thus supporting the findings of specific methanogenic activity measurements. TRFLP data supported the hypothesis that the deviation between the replicated reactors, in terms of treatment efficiency, was associated with succession within the microbial communities present, and indicated that community development was linked to both operating temperature and wastewater composition. Fluorescence in situ hybridization (FISH) was also applied, to quantitatively assess the abundance of selected microbial groups, and revealed the underestimation of the abundance Methanosarcina by gene cloning analysis and demonstrated the spatial arrangement of these organisms within the architecture of the low-temperature solvent-degrading anaerobic biofilms.  相似文献   
60.
为了探讨循环肿瘤细胞(circulating tumor cells,CTCs)在肺癌诊断中的应用及临床意义,本研究收集了我院2014年10月至2017年12月收治并确诊的肺癌患者87例、健康体检者40名以及肺部良性疾病患者50例作为研究对象,采用人循环肿瘤细胞试剂盒测定外周血CTC水平,两组间比较采用Mann-Whitney U检验,多组间比较采用Kruskal-Wallis检验,利用ROC曲线评价CTC在肺癌诊断上的灵敏度以及特异度。实验发现肺癌患者CTC水平(M=12.67 Unints/3 mL)显著高于肺部良性病患者(M=4.76 Unints/3 mL)和健康者(M=4.48 Unints/3 mL),差异存在统计学意义(p<0.001)。在不同性别、不同年龄段以及不同病理类型之间肺癌患者的CTC水平比较差异无统计学意义(p>0.05)。Ⅲ+Ⅳ期肺癌患者CTC水平显著高于Ⅰ+Ⅱ期患者,差异存在统计学意义(p<0.001)。有远处转移的肺癌患者CTC水平显著高于无远处转移的肺癌患者,差异存在统计学意义(p<0.001)。ROC曲线下面积为0.878(95%CI 0.820~0.936),临界值为6.34 Unints/3 mL,对应的灵敏度为0.77,特异度为0.989。本研究初步认为,CTC检测对肺癌诊断具有较高的灵敏度以及特异度,可能存在重要的临床应用价值。  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