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   229篇
  免费   5篇
  234篇
  2024年   2篇
  2023年   4篇
  2022年   5篇
  2021年   4篇
  2020年   3篇
  2019年   13篇
  2018年   6篇
  2017年   4篇
  2016年   9篇
  2015年   14篇
  2014年   10篇
  2013年   20篇
  2012年   17篇
  2011年   15篇
  2010年   19篇
  2009年   9篇
  2008年   18篇
  2007年   12篇
  2006年   4篇
  2005年   9篇
  2004年   12篇
  2003年   7篇
  2002年   3篇
  2000年   2篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1986年   1篇
  1982年   1篇
  1980年   1篇
  1975年   1篇
排序方式: 共有234条查询结果,搜索用时 15 毫秒
1.
THELASERTOMOGRAPHICALMETHODUSINGMINIMUMOFPROJECTIONFORBIOLOGICALOBJECTSTRUCTURESTUDYYuriN.Kulchin;OlegB.Vitrik;OlegV.Kirichei...  相似文献   
2.
    
Baikal amphipods are one of the most unique freshwater species flocks of over 350 morphological species and subspecies playing multiple ecological roles in this ancient lake. However, molecular phylogeny studies accumulate evidence that this number is underestimated. Previously, we showed that an abundant littoral species Eulimnogammarus verrucosus comprised at least three genetic lineages: southern (S), western (W), and eastern (E), inhabiting corresponding parts of Baikal shore. The Angara River is the only outflow of the lake and is inhabited by amphipods originating from Baikal, which were previously analysed only morphologically. The river has parts with strong current or closed bays as opposed to sea-like conditions of Lake Baikal, which raises the question of which species were able to adapt here. Here we studied the phylogeny of E. verrucosus from the Angara River, which could be reached by two lineages, S and W. We analysed 17 sites from 0.6 to 650 km from the outflow. Cytochrome c oxidase subunit I (COI) and 18S rRNA analysis showed that the sites closest to Baikal were inhabited by the S and W lineages sympatrically. The other sites were inhabited by the S lineage at both banks and also by the novel A (Angara) lineage. The A lineage was the first to split up from the last common ancestor of all E. verrucosus. Our data confirm the importance of considering cryptic diversity in ecological monitoring, and in order to simplify the identification of the genetic lineage, we developed a web-app speCOIdent.  相似文献   
3.
4.
Photosynthesis Research - This paper is a tribute to a great scientist and an authentic “honest man” that was Jean Lavorel (1928–2021). He was a pioneer in research on the primary...  相似文献   
5.
We describe the application of a novel screening approach that combines automated yeast genetics, synthetic genetic array (SGA) analysis, and a high-content screening (HCS) system to examine mitotic spindle morphogenesis. We measured numerous spindle and cellular morphological parameters in thousands of single mutants and corresponding sensitized double mutants lacking genes known to be involved in spindle function. We focused on a subset of genes that appear to define a highly conserved mitotic spindle disassembly pathway, which is known to involve Ipl1p, the yeast aurora B kinase, as well as the cell cycle regulatory networks mitotic exit network (MEN) and fourteen early anaphase release (FEAR). We also dissected the function of the kinetochore protein Mcm21p, showing that sumoylation of Mcm21p regulates the enrichment of Ipl1p and other chromosomal passenger proteins to the spindle midzone to mediate spindle disassembly. Although we focused on spindle disassembly in a proof-of-principle study, our integrated HCS-SGA method can be applied to virtually any pathway, making it a powerful means for identifying specific cellular functions.  相似文献   
6.
    

Background

While the RNA world hypothesis is widely accepted, it is still far from complete: the existence of self-replicating ribozyme, consisting of potentially hundreds of nucleotides, is a core assumption for the majority of RNA world models. The appearance of such long RNA molecules under prebiotic conditions is not self-evident. Recombination seems to be a plausible way of creating RNA diversity, resulting in the appearance of functional RNAs, capable of self-replicating.

Methods

We report here on the study of recombination process modelled with two 96 nts RNA fragments. Detection of recombination products was performed with RT-PCR followed by TA-cloning and Sanger sequencing.

Results

A wide range of recombinant products was detected. We found that (i) the most efficient ligation was observed for RNA species forming bulges or internal loops, with ligation partners located within the loop; (ii) a strong preference was observed for formation of a few types of major products with a large variety of minor products; (iii) ligation could occur with participation of either 2′,3′-cyclophosphate or 5′-ppp; (iv) the presence of key reaction components, i.e. 5′ppp-RNAs, enabled the formation of additional types of product; (v) molecular dynamics simulations of one of the most abundant products suggests that the ligation results in a preferable formation of 2′-5′- rather than 3′-5′-linkages.

Conclusions

The study demonstrates regularities of new RNA molecules formation with non-enzymatic recombination process.

General significance

Our findings provide new data supporting the RNA World hypothesis and show the way of new RNA sequences emergence under prebiotic conditions.  相似文献   
7.
We previously reported that fragments of exogenous double-stranded DNA can be internalized by mouse bone marrow cells without any transfection. Our present analysis shows that only 2% of bone marrow cells take up the fragments of extracellular exogenous DNA. Of these, ~ 45% of the cells correspond to CD34 + hematopoietic stem cells. Taking into account that CD34 + stem cells constituted 2.5% of the total cell population in the bone marrow samples analyzed, these data indicate that as much as 40% of CD34 + cells readily internalize fragments of extracellular exogenous DNA. This suggests that internalization of fragmented dsDNA is a general feature of poorly differentiated cells, in particular CD34 + bone marrow cells.  相似文献   
8.
9.
10.
CRABP1 (cellular retinoic acid binding protein 1) belongs to the family of fatty acid binding proteins. Retinoic acid binding is the only known functional activity of this protein. The role of CRABP1 in human carcinogenesis remains poorly understood. Here, for the first time we demonstrated pro-metastatic and pro-tumorigenic activity of CRABP1 in mesenchymal tumors. Further functional analysis revealed that the pro-tumorigenic effect of CRABP1 does not depend on retinoic acid binding activity. These results suggest that CRABP1 could have an alternative intracellular functional activity that contributes to the high malignancy of transformed mesenchymal cells. Microarray analysis detected CRABP1-mediated alterations in the expression of about 100 genes, including those encoding key regulatory proteins. CRABP1 is ubiquitously expressed in monophasic synovial sarcomas, while in biphasic synovial sarcomas it is expressed uniquely by the spindle cells of the aggressive mesenchymal component. High level of CRABP1 expression is associated with lymph node metastasis and poor differentiation/high grade of pancreatic neuroendocrine tumors (pNETs). Presented data suggest CRABP1 as a promising biomarker of pNETs’ clinical behavior. Our results give the first evidence of pro-tumorigenic and pro-metastatic activity of CRABP1 in mesenchymal and neuroendocrine tumors.  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