全文获取类型
收费全文 | 485617篇 |
免费 | 47116篇 |
国内免费 | 222篇 |
出版年
2018年 | 5223篇 |
2017年 | 5266篇 |
2016年 | 8433篇 |
2015年 | 14044篇 |
2014年 | 15041篇 |
2013年 | 18301篇 |
2012年 | 20402篇 |
2011年 | 18037篇 |
2010年 | 12492篇 |
2009年 | 11612篇 |
2008年 | 14559篇 |
2007年 | 14960篇 |
2006年 | 13998篇 |
2005年 | 20269篇 |
2004年 | 19052篇 |
2003年 | 16606篇 |
2002年 | 13186篇 |
2001年 | 16089篇 |
2000年 | 15362篇 |
1999年 | 13601篇 |
1998年 | 5536篇 |
1997年 | 5134篇 |
1996年 | 4813篇 |
1995年 | 4673篇 |
1994年 | 4582篇 |
1993年 | 4485篇 |
1992年 | 11957篇 |
1991年 | 11534篇 |
1990年 | 11463篇 |
1989年 | 11028篇 |
1988年 | 10471篇 |
1987年 | 9929篇 |
1986年 | 8939篇 |
1985年 | 9306篇 |
1984年 | 7625篇 |
1983年 | 6607篇 |
1982年 | 5296篇 |
1981年 | 4704篇 |
1980年 | 4448篇 |
1979年 | 7357篇 |
1978年 | 5665篇 |
1977年 | 5201篇 |
1976年 | 4915篇 |
1975年 | 5348篇 |
1974年 | 5856篇 |
1973年 | 5929篇 |
1972年 | 5389篇 |
1971年 | 5051篇 |
1970年 | 4314篇 |
1969年 | 4237篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
B Daneholt 《Journal of molecular biology》1970,49(2):381-391
63.
64.
65.
66.
Isolation of viral coat protein mutants with altered assembly and aggregation properties 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A method was developed to screen bacteria for synthesis of mutant proteins with altered assembly and solubility properties using bacteriophage MS2 coat protein as a model self-associating protein. Colonies expressing coat protein from a plasmid were covered with an agarose overlay under conditions that caused the lysis of some of the cells in each colony. The proteins thus liberated diffused through the overlay at rates depending on their molecular sizes. After transfer of the proteins to a nitrocellulose membrane, probing with coat protein-specific antiserum revealed spots whose sizes and intensities were related to the aggregation state of coat protein. The method was employed in the isolation of assembly defective mutants and to find soluble variants of an aggregation-prone coat protein mutant. 相似文献
67.
Maria Rebelo Claudia Sousa Howard M. Shapiro Maria M. Mota Martin P. Grobusch Thomas H?nscheid 《PloS one》2013,8(4)
Resistance of Plasmodium falciparum to almost all antimalarial drugs, including the first-line treatment with artemisinins, has been described, representing an obvious threat to malaria control. In vitro antimalarial sensitivity testing is crucial to detect and monitor drug resistance. Current assays have been successfully used to detect drug effects on parasites. However, they have some limitations, such as the use of radioactive or expensive reagents or long incubation times. Here we describe a novel assay to detect antimalarial drug effects, based on flow cytometric detection of hemozoin (Hz), which is rapid and does not require any additional reagents. Hz is an optimal parasite maturation indicator since its amount increases as the parasite matures. Due to its physical property of birefringence, Hz depolarizes light, hence it can be detected using optical methods such as flow cytometry. A common flow cytometer was adapted to detect light depolarization caused by Hz. Synchronized in vitro cultures of P. falciparum were incubated for 48 hours with several antimalarial drugs. Analysis of depolarizing events, corresponding to parasitized red blood cells containing Hz, allowed the detection of parasite maturation. Moreover, chloroquine resistance and the inhibitory effect of all antimalarial drugs tested, except for pyrimethamine, could be determined as early as 18 to 24 hours of incubation. At 24 hours incubation, 50% inhibitory concentrations (IC50) were comparable to previously reported values. These results indicate that the reagent-free, real-time Hz detection assay could become a novel assay for the detection of drug effects on Plasmodium falciparum. 相似文献
68.
69.
The Biopolymer Markup Language. 总被引:6,自引:0,他引:6
D Feny? 《Bioinformatics (Oxford, England)》1999,15(4):339-340
SUMMARY: An XML derived from a data model designed to be a hierarchical representation of an organism has been specified and a browser to use this language has been developed. AVAILABILITY: The language definition is available in HTML form at http://www.proteometrics.com/BIOML/. The BioML browser is available on request from the author. 相似文献
70.
Defective transducing phages carrying aroG, the structural gene for phenylalanine (phe)-inhibitable phospho-2-keto-heptonate aldolase (EC 4.1.2.15; previously known as 3-deoxy-D-arabinoheptulosonate-7-phosphate synthetase[phe]), have been isolated, and DNA from two of these phages has been used to construct a restriction map of the region from att lambda to aroG. A 7.6-kb PstI-HindIII fragment from one of these phages was cloned into pBR322 and shown to contain aroG. The location of aroG within the 7.6 kb was established by subcloning and Tn3 transpositional mutagenesis. A fragment carrying the aroG promoter and operator has been cloned into a high copy number promoter-cloning vector (pMC489), and the resulting aroGpo-LacZ' (alpha) fusion subcloned in a low copy number vector. Strains with this fusion on the low copy number vector exhibit negative regulation of beta-galactosidase expression by both phenylalanine and tryptophan and positive regulation by tyrosine in a tyrR+ background. 相似文献