全文获取类型
收费全文 | 693篇 |
免费 | 42篇 |
出版年
2019年 | 6篇 |
2018年 | 6篇 |
2017年 | 8篇 |
2016年 | 6篇 |
2015年 | 20篇 |
2014年 | 17篇 |
2013年 | 19篇 |
2012年 | 25篇 |
2011年 | 29篇 |
2010年 | 27篇 |
2009年 | 27篇 |
2008年 | 33篇 |
2007年 | 21篇 |
2006年 | 27篇 |
2005年 | 29篇 |
2004年 | 17篇 |
2003年 | 17篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 20篇 |
1999年 | 22篇 |
1998年 | 11篇 |
1995年 | 6篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 17篇 |
1988年 | 22篇 |
1987年 | 5篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 15篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1974年 | 8篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 7篇 |
1969年 | 6篇 |
1968年 | 6篇 |
1966年 | 6篇 |
1965年 | 7篇 |
1964年 | 4篇 |
1963年 | 5篇 |
排序方式: 共有735条查询结果,搜索用时 15 毫秒
21.
Molecular evolution of voltage-sensitive ion channel genes: on the origins of electrical excitability 总被引:14,自引:0,他引:14
We have analyzed nucleic acid and amino acid sequence alignments of a
variety of voltage-sensitive ion channels, using several methods for
phylogenetic tree reconstruction. Ancient duplications within this family
gave rise to three distantly related groups, one consisting of the Na+ and
Ca++ channels, another the K+ channels, and a third including the cyclic
nucleotide-binding channels. A series of gene duplications produced at
least seven mammalian homologues of the Drosophila Shaker K+ channel;
clones of only three of these genes are available from all three mammalian
species examined (mouse, rat, and human), pointing to specific genes that
have yet to be recovered in one or another of these species. The
Shaw-related K+ channels and the Na+ channel family have also undergone
considerable expansion in mammals, relative to flies. These expansions
presumably reflect the needs of the high degree of physiological and
neuronal complexity of mammals. Analysis of the separate domains of the
four-domain channels (Ca++ and Na+) supports their having evolved by two
sequential gene duplications and implies the historical existence of a
functional two-domain channel.
相似文献
22.
The rate of exchange of peptide group NH hydrogens with the hydrogens of aqueous solvent is sensitive to neighboring side chains. To evaluate the effects of protein side chains, all 20 naturally occurring amino acids were studied using dipeptide models. Both inductive and steric blocking effects are apparent. The additivity of nearest-neighbor blocking and inductive effects was tested in oligo-and polypeptides and, suprisingly, confirmed. Reference rates for alanine-containing peptides were determined and effects of temperature considered. These results provide the information necessary to evaluate measured protein NH to ND exchange rates by comparing them with rates to be expected for the same amino acid sequence is unstructured aligo- and polypeptides. The application of this approach to protein studies is discussed. © 1993 Wiley-Liss, Inc. 相似文献
23.
Modulation of Saccharomyces Cerevisiae DNA Double-Strand Break Repair by Srs2 and Rad51 总被引:4,自引:1,他引:3
下载免费PDF全文
![点击此处可从《Genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
RAD52 function is required for virtually all DNA double-strand break repair and recombination events in Saccharomyces cerevisiae. To gain greater insight into the mechanism of RAD52-mediated repair, we screened for genes that suppress partially active alleles of RAD52 when mutant or overexpressed. Described here is the isolation of a phenotypic null allele of SRS2 that suppressed multiple alleles of RAD52 (rad52B, rad52D, rad52-1 and KlRAD52) and RAD51 (KlRAD51) but failed to suppress either a rad52δ or a rad51δ. These results indicate that SRS2 antagonizes RAD51 and RAD52 function in recombinational repair. The mechanism of suppression of RAD52 alleles by srs2 is distinct from that which has been previously described for RAD51 overexpression, as both conditions were shown to act additively with respect to the rad52B allele. Furthermore, overexpression of either RAD52 or RAD51 enhanced the recombination-dependent sensitivity of an srs2δ RAD52 strain, suggesting that RAD52 and RAD51 positively influence recombinational repair mechanisms. Thus, RAD52-dependent recombinational repair is controlled both negatively and positively. 相似文献
24.
Radioimmunoassay of atrial natriuretic factor (ANF) in rat atria 总被引:1,自引:0,他引:1
J Gutkowska G Thibault R W Milne P Januszewicz P W Schiller M Cantin J Genest 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1984,176(2):105-108
We describe a solid phase radioimmunoassay for atrial natriuretic factor (ANF) and its application for measurement of this peptide in homogenates of rat atria. The method uses a synthetic 26 amino-acid fragment (8-33 ANF) of the native peptide. Sample (or standard) are incubated with the rabbit anti-8-33 ANF antiserum in peptide (8-33 ANF)-coated wells. Then an excess of I125 goat anti-rabbit IgG is added. The radioactivity bound is directly proportional to the amount of ANF present. The concentration of immunoreactive ANF has been found to be about 4 times higher in the right atrium than in the left atrium of the rat. 相似文献
25.
26.
27.
The titre and immunoglobulin class of antibodies against Candida albicans in serum from 60 non-pregnant women was determined. IgG titres up to 132, IgA titres up to 18, and IgM titres up to 14 were detected in 30 women with vaginal candidiasis. Similar titres were found in 20 women harbouring yeasts in the mouth or rectum, and in 10 women who were not harbouring yeasts in the vagina, mouth or rectum. Serum fractionation confirmed that antibodies to C. albicans are found in the three immunoglobulin classes and that these antibodies reside in highest titre in the IgG class. No secretory IgA antibodies against C. albicans were detected in the serum of these women. 相似文献
28.
Mapping of antigenic determinants of human apolipoprotein B using monoclonal antibodies against low density lipoproteins 总被引:16,自引:0,他引:16
Y L Marcel M Hogue R Theolis R W Milne 《The Journal of biological chemistry》1982,257(22):13165-13168
The reactivity of a series of monoclonal antibodies directed against human low density lipoproteins (LDL) has been tested with hepatic and intestinal apolipoprotein B (apo-B) termed B-100 and B-48, respectively (Kane, J. P., Hardman, D. A., and Paulus, H. E. (1980) Proc. Natl. Acad. Sci. U. S. A. 77, 2465-2469). Whereas those antibodies that have been previously shown to recognize determinants close to the LDL receptor recognition site reacted only with B-100, two antibodies specific for other regions of apo-B reacted with both B-100 and B-48. Therefore, it is probable that sequence homologies exist between the two proteins and it must be considered that all or parts of the B-48 sequence may be contained within that of B-100. The specificity of the reaction of these antibodies with proteins designated B-74 and B-26 supports the concept that they represent complementary fragments of B-100. The present results have been incorporated in a theoretical map of the antigenic determinants recognized by these antibodies on the LDL apo-B. 相似文献
29.
30.