全文获取类型
收费全文 | 873篇 |
免费 | 101篇 |
专业分类
974篇 |
出版年
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 15篇 |
2017年 | 10篇 |
2016年 | 27篇 |
2015年 | 26篇 |
2014年 | 39篇 |
2013年 | 44篇 |
2012年 | 69篇 |
2011年 | 47篇 |
2010年 | 34篇 |
2009年 | 30篇 |
2008年 | 50篇 |
2007年 | 40篇 |
2006年 | 49篇 |
2005年 | 29篇 |
2004年 | 46篇 |
2003年 | 33篇 |
2002年 | 24篇 |
2001年 | 38篇 |
2000年 | 22篇 |
1999年 | 15篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 12篇 |
1990年 | 18篇 |
1989年 | 15篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1974年 | 6篇 |
1970年 | 6篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1967年 | 5篇 |
1966年 | 4篇 |
排序方式: 共有974条查询结果,搜索用时 0 毫秒
961.
962.
963.
964.
Subodh Kumar Sinha Arupratan Dasgupta Anita Baranwal Shelly Praveen 《Journal of plant biochemistry and biotechnology.》2004,13(1):43-46
Tomato Leaf Curl Virus (ToLCV)-infected samples collected from four different ecological zones of India: Northern zone, NewDelhi (IARI) [ToLCNDV-IARI]; Central zone, Jabalpur [ToLCV-Jb], Raipur [ToLCV-Rp] and Southern zone, Dharwad [ToLCV-Dh] were maintained by whitefly transmission into tomato cv Pusa Early Dwarf. Replicase gene coding for replication initiator protein (Rep) was amplified by PCR using gene specific primers, yielding an amplicon of 1086 bp for all the isolates. Sequence analysis of the rep amplicons of all the Indian isolates of ToLCV causing the disease clearly shows the presence oftwo subgroups irrespective of their geographical evolution. Isolates belonging to subgroup I comprising of tomato leaf curl virus-New Delhi (ToLCV-NDe) having bipartite genome are conserved within themselves and showed 94–95% nucleotide sequence homology. Second subgroup comprising of tomato leaf curl virus-Bangalore (ToLCBV) having monopartite genome and conserved among themselves, but showed only 73-75% homology with the subgroup I. In phylogenetic tree analysis, ToLCV-NDe appeared in a different cluster than ToLCV-Ban. All the four isolates used in this study fall in ToLCV-NDe group based on their replicase gene sequences. The specificity determinant located at N terminal suggests ToLCV-NDe and ToLCV-Rp as mild isolates. 相似文献
965.
Effect of diethylpyrocarbonate on the biological activities of botulinum neurotoxin types A and E 总被引:1,自引:0,他引:1
The single chain (unnicked) type-E and the dichain (nicked) type-A botulinum neurotoxins were modified with diethylpyrocarbonate (ethoxyformic anhydride), a reagent highly specific for histidine residues. The type-E neurotoxin could be completely detoxified without causing detectable damage to its serological reactivity. Under identical modification reaction conditions, the type A was incompletely detoxified with some alteration in its serological reactivity. Modification of histidine residues was evident from the increase in absorbance at 240 nm, and reactivation of the detoxified proteins by reversing the modification with hydroxylamine. The completely detoxified type-E neurotoxin, used as toxoid, elicited antibodies in rabbits. The antiserum precipitated and neutralized the neurotoxin. This toxoid is homogeneous as tested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereas the traditional toxoid produced with formaldehyde is heterogeneous. 相似文献
966.
Background
For a proper understanding of protein structure and folding it is important to know if a polypeptide segment adopts a conformation inherent in the sequence or it depends on the context of its flanking secondary structures. Turns of various lengths have been studied and characterized starting from three-residue γ-turn to six-residue π-turn. The Schellman motif occurring at the C-terminal end of α-helices is a classical example of hydrogen bonded π-turn involving residues at (i) and (i+5) positions. Hydrogen bonded and non-hydrogen bonded β- and α-turns have been identified previously; likewise, a systematic characterization of π-turns would provide valuable insight into turn structures. 相似文献967.
968.
C. S. Nair I. Singh M. S. Malhotra A. Dasgupta S. K. Dass 《International journal of biometeorology》1977,21(4):332-336
Seven lowlander soldiers who had 1st to 3rd degree of frostbite and 8 lowlander soldiers who recovered from high altitude pulmonary oedema were tested for cold pressor response at 260 m, 26°C, 6.8°C and 4,085 m, 26°C, 6.8°C. 8 lowlander soldiers (Control subjects) of comparable age group were tested for their cold pressor response at 260 m, 26°C and 3,300 m, 26°C. Another group of control subjects from the laboratory were also tested at 2,121 m, 26°C. There was a highly significant decrease in cold pressor response of the frostbite subjects at 260 m, 26°C and a very significant increase at 260 m, 6.8°C as compared to non-frostbite subjects. The subjects who recovered from high altitude pulmonary oedema did not show significant differences as compared with the control subjects. The results suggest certain basic physiological differences in regulation of supply of blood to the extremities under condition of general and local cold exposure. 相似文献
969.
Several HindIII monomer units of a tandemly repeated nuclear DNA sequence ofBrassica campestris andBrassica juncea (Cruciferae) have been cloned and sequenced. The monomer units, of 177 bp length, are AT-rich and share 88% homology between themselves and more than 65% homology with similar repeats of otherCruciferae likeBrassica oleracea, Sinapis alba andRaphanus sativus. Thus unlike the rapid divergence of tandemly repeated satellite DNA in other organisms, this DNA element is highly conserved thus indicating its importance. 相似文献
970.