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   1988篇
  免费   89篇
  国内免费   168篇
  2024年   1篇
  2023年   21篇
  2022年   28篇
  2021年   45篇
  2020年   38篇
  2019年   55篇
  2018年   40篇
  2017年   32篇
  2016年   50篇
  2015年   64篇
  2014年   169篇
  2013年   188篇
  2012年   148篇
  2011年   120篇
  2010年   85篇
  2009年   118篇
  2008年   129篇
  2007年   130篇
  2006年   103篇
  2005年   87篇
  2004年   70篇
  2003年   77篇
  2002年   61篇
  2001年   38篇
  2000年   50篇
  1999年   31篇
  1998年   30篇
  1997年   20篇
  1996年   25篇
  1995年   27篇
  1994年   18篇
  1993年   19篇
  1992年   27篇
  1991年   15篇
  1990年   8篇
  1989年   14篇
  1988年   7篇
  1987年   12篇
  1986年   7篇
  1985年   11篇
  1984年   7篇
  1983年   7篇
  1982年   6篇
  1981年   3篇
  1980年   2篇
  1979年   1篇
  1976年   1篇
排序方式: 共有2245条查询结果,搜索用时 31 毫秒
101.
近年来植物基因组测序物种数量的指数增长, 为我们对植物环境适应性状的遗传和变异的全面理解提供了保障。磷脂酰乙醇胺结合蛋白(phosphatidylethanolamine-binding protein, PEBP)在植物的开花转变和株型建立中起着重要作用, 一直是植物生物学研究关注的热点领域之一。然而对该家族并没有利用新近测序的基因组数据进行比较基因组分析, 制约了对其在分子水平上的进化研究。为了确定PEBP基因家族的分子进化机制, 本研究利用生物信息学方法开展了7种十字花科植物拟南芥(Arabidopsis thaliana)、琴叶拟南芥(A. lyrata)、小鼠耳芥(A. pumila)、亚麻荠(Camelina sativa)、甘蓝(Brassica oleracea)、白菜(B. rapa)和油菜(B. napus)的PEBP基因家族成员的全基因组鉴定、结构特征和比较进化分析。从7个物种中共鉴定出91个PEBP基因, 系统进化分析表明它们分属5个亚家族: MFTFT/TSF、TFL1、CENBFT。基因结构分析发现甘蓝、白菜和油菜的CEN基因内含子明显比其余4个物种的内含子长。蛋白结构域分析表明MFT比其他4个亚家族成员少了一个motif 2, TFL1比其他亚家族多了motif 8。选择压力分析发现7个物种PEBP同源基因均受到较强的纯化选择, 其中TFL1亚家族受到的纯化选择最弱。共线性分析表明十字花科植物PEBP基因家族随古代多倍体事件发生不同程度的扩张, TSF在甘蓝、白菜和油菜中丢失。非生物胁迫下, 在拟南芥中过量表达小鼠耳芥的一个MFT基因, 转基因拟南芥种子的萌发率明显低于野生型, 暗示MFT基因在调控种子萌发上的功能保守。本研究为深入研究十字花科植物PEBP基因的进化特征和生物学功能奠定了基础。  相似文献   
102.
103.
FLOTILLIN-1 and FLOTILLIN-2 are membrane rafts associated proteins that have been implicated in insulin and growth factor signaling, endocytosis, cell migration, proliferation, differentiation, cytoskeleton remodeling and membrane trafficking. Furthermore, FLOTILLINs also play important roles in the progression of cancer and neurodegenerative diseases. In this study, the roles of flotillins are investigated in planarian Dugesia japonica. The results show that Djflotillin-1 and Djflotillin-2 play a key role in homeostasis maintenance and regeneration process by regulating the proliferation of the neoblast cells, they are not involved in the maintenance and regeneration of the central nervous system in planarians.  相似文献   
104.
One major challenge in the bioconversion of lignocelluloses into ethanol is to develop Saccharomyces cerevisiae strains that can utilize all available sugars in biomass hydrolysates, especially the d -xylose and l -arabinose that cannot be fermented by the S. cerevisiae strain naturally. Here, we integrated an l -arabinose utilization cassette (AUC) into the genome of an efficient d -xylose fermenting industrial diploid S. cerevisiae strain CIBTS0735 to make strain CIBTS1972. After evolving on arabinose, CIBTS1974 with excellent fermentation capacity was obtained. A comparison between genome sequences of strains CIBTS1974 and CIBTS1972 revealed that the copy number of the AUC had increased from 1 to 12. We then constructed the AUC null-mutant CIBTS1975 and gradually rescued the l -arabinose utilization defect by integrating AUC iteratively. On the other hand, the parental strain CIBTS0735 was able to acquire the same performance as CIBTS1974 by the direct introduction of 12 copies of the AUC; the performance was further improved by adding two more copies. Besides, we found that not the two transporters present in the AUC were both needed during l -arabinose utilization, GAL2 was necessary and STP2 was not essential. We have described for the first time that a high copy number of AUC is sufficient for the strain to metabolize l -arabinose efficiently independent of evolution.  相似文献   
105.
In this study, we present a minimal template design and accompanying methods to produce assayable quantities of custom sequence proteins within 24 hr from receipt of inexpensive gene fragments from a DNA synthesis vendor. This is done without the conventional steps of plasmid cloning or cell-based amplification and expression. Instead the linear template is PCR amplified, circularized, and isothermally amplified using a rolling circle polymerase. The resulting template can be used directly with cost-optimized, scalably-manufactured Escherichia coli extract and minimal supplement reagents to perform cell-free protein synthesis (CFPS) of the template protein. We demonstrate the utility of this template design and 24 hr process with seven fluorescent proteins (sfGFP, mVenus, mCherry, and four GFP variants), three enzymes (chloramphenicol acetyltransferase, a chitinase catalytic domain, and native subtilisin), a capture protein (anti-GFP nanobody), and 2 antimicrobial peptides (BP100 and CA(1–7)M(2–9)). We detected each of these directly from the CFPS reaction using colorimetric, fluorogenic, and growth assays. Of especial note, the GFP variant sequences were found from genomic screening data and had not been expressed or characterized before, thus demonstrating the utility of this approach for phenotype characterization of sequenced libraries. We also demonstrate that the rolling circle amplified version of the linear template exhibits expression similar to that of a complete plasmid when expressing sfGFP in the CFPS reaction. We evaluate the cost of this approach to be $61/mg sfGFP for a 4 hr reaction. We also detail limitations of this approach and strategies to overcome these, namely proteins with posttranslational modifications.  相似文献   
106.
107.
108.
109.
Phytophthora nicotianae is a phytopathogenic oomycete with a wide host range and worldwide distribution. Rapid detection and diagnosis at the early stages of disease development are important for the effective control of P. nicotianae. In this study, we designed a simple and rapid loop‐mediated isothermal amplification (LAMP)‐based detection method for P. nicotianae. We tested three DNA extraction methods and selected the Kaneka Easy DNA Extraction Kit version 2, which is rapid and robust for LAMP‐based detection. The designed primers were tested using mycelial DNA from 35 species (81 isolates) of Phytophthora, 12 species (12 isolates) of Pythium, one isolate of Phytopythium and one isolate each from seven other soil‐borne pathogens. All of the 42 P. nicotianae isolates were detected by these primers, and no other isolates gave positive results. Three isolates were tested for the sensitivity of the reaction, and the lowest amounts of template DNA that could be detected were 10 fg for two isolates and 1 fg for the third. The target was detected within 25 min in all tested samples, including DNA extracted from both inoculated and naturally infected plants. In contrast, PCR assays with P. nicotianae‐specific primers failed or showed weakened detection in several samples. Thus, we found that the rapid DNA extraction and LAMP assay methods developed in this study can be used to detect P. nicotianae with high sensitivity, specificity and stability.  相似文献   
110.
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