全文获取类型
收费全文 | 1455篇 |
免费 | 95篇 |
国内免费 | 4篇 |
专业分类
1554篇 |
出版年
2023年 | 10篇 |
2022年 | 20篇 |
2021年 | 28篇 |
2020年 | 20篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 18篇 |
2016年 | 45篇 |
2015年 | 52篇 |
2014年 | 66篇 |
2013年 | 88篇 |
2012年 | 89篇 |
2011年 | 78篇 |
2010年 | 54篇 |
2009年 | 59篇 |
2008年 | 64篇 |
2007年 | 70篇 |
2006年 | 78篇 |
2005年 | 58篇 |
2004年 | 50篇 |
2003年 | 56篇 |
2002年 | 49篇 |
2001年 | 46篇 |
2000年 | 45篇 |
1999年 | 30篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1992年 | 19篇 |
1991年 | 14篇 |
1990年 | 22篇 |
1989年 | 31篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 13篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 16篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 12篇 |
1975年 | 11篇 |
1970年 | 6篇 |
1968年 | 8篇 |
1966年 | 5篇 |
排序方式: 共有1554条查询结果,搜索用时 0 毫秒
21.
Arun Agrawal 《Human ecology: an interdisciplinary journal》1993,21(3):261-279
This paper describes and then analyzes the decision-making arrangements that prevail among the Raikas—nomadic shepherds from Western India. The paper suggests, using a simple analytical framework, that the existing distribution of decision-making during migration helps the Raikasto utilize available economies of scale, represent the different interest groups in their collectives, and control their decision-makers. At the same time, the ordinary shepherds in the camp are able to extract a comfortable subsistence from a complex and harsh environment by delegating much of their decision-making responsibilities to the leaders in the camp. To the extent shepherds in other parts of the world migrate over long distances and must confront similar issues of delegation of responsibilities and control over decision-makers, the analysis holds general relevance. 相似文献
22.
Satish Mohan Gunasekar Palanikumar Asensio Juan A. Agrawal Devendra K. 《Molecular and cellular biochemistry》2020,474(1-2):219-228
Molecular and Cellular Biochemistry - Intracoronary stenting is a common procedure in patients with coronary artery disease (CAD). Stent deployment stretches and denudes the endothelial layer,... 相似文献
23.
Jung YH Jeong SH Kim SH Singh R Lee JE Cho YS Agrawal GK Rakwal R Jwa NS 《Proteomics》2012,12(6):878-900
Magnaporthe oryzae is a devastating blast fungal pathogen of rice (Oryza sativa L.) that causes dramatic decreases in seed yield and quality. During the early stages of infection by this pathogen, the fungal spore senses the rice leaf surface, germinates, and penetrates the cell via an infectious structure known as an appressorium. During this process, M. oryzae secretes several proteins; however, these proteins are largely unknown mainly due to the lack of a suitable method for isolating secreted proteins during germination and appressoria formation. We examined the secretome of M. oryzae by mimicking the early stages of infection in vitro using a glass plate (GP), PVDF membrane, and liquid culture medium (LCM). Microscopic observation of M. oryzae growth revealed appressorium formation on the GP and PVDF membrane resembling natural M. oryzae-rice interactions; however, appresorium formation was not observed in the LCM. Secreted proteins were collected from the GP (3, 8, and 24 h), PVDF membrane (24 h), and LCM (48 h) and identified by two-dimensional gel electrophoresis (2DE) followed by tandem mass spectrometry. The GP, PVDF membrane, and LCM-derived 2D gels showed distinct protein patterns, indicating that they are complementary approaches. Collectively, 53 nonredundant proteins including previously known and novel secreted proteins were identified. Six biological functions were assigned to the proteins, with the predominant functional classes being cell wall modification, reactive oxygen species detoxification, lipid modification, metabolism, and protein modification. The in vitro system using GPs and PVDF membranes applied in this study to survey the M. oryzae secretome, can be used to further our understanding of the early interactions between M. oryzae and rice leaves. 相似文献
24.
The aggregation of biotherapeutics is a major hindrance to the development of successful drug candidates; however, the propensity to aggregate is often identified too late in the development phase to permit modification to the protein's sequence. Incorporating rational design for the stability of proteins in early discovery has numerous benefits. We engineered out aggregation-prone regions on the Fab domain of a therapeutic monoclonal antibody, bevacizumab, to rationally design a biobetter drug candidate. With the purpose of stabilizing bevacizumab with respect to aggregation, 2 strategies were undertaken: single point mutations of aggregation-prone residues and engineering a glycosylation site near aggregation-prone residues to mask these residues with a carbohydrate moiety. Both of these approaches lead to comparable decreases in aggregation, with an up to 4-fold reduction in monomer loss. These single mutations and the new glycosylation pattern of the Fab domain do not modify binding to the target. Biobetters with increased stability against aggregation can therefore be generated in a rational manner, by either removing or masking the aggregation-prone region or crowding out protein-protein interactions. 相似文献
25.
Wan Yun Ho Jer-Cherng Chang Kenneth Lim Amaury Cazenave-Gassiot Aivi T. Nguyen Juat Chin Foo Sneha Muralidharan Ashley Viera-Ortiz Sarah J.M. Ong Jin Hui Hor Ira Agrawal Shawn Hoon Olubankole Aladesuyi Arogundade Maria J. Rodriguez Su Min Lim Seung Hyun Kim John Ravits Shi-Yan Ng Markus R. Wenk Edward B. Lee Greg Tucker-Kellogg Shuo-Chien Ling 《The Journal of cell biology》2021,220(9)
26.
Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene 总被引:7,自引:1,他引:7
We have analyzed the conserved regions of the gene coding for the
circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria
parasite. The closest evolutionary relative of P. falciparum, the agent of
malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is
consistent with the hypothesis that P. falciparum is an ancient human
parasite, associated with humans since the divergence of the hominids from
their closest hominoid relatives. Three other human Plasmodium species are
each genetically indistinguishable from species parasitic to nonhuman
primates; that is, for the DNA sequences included in our analysis, the
differences between species are not greater than the differences between
strains of the human species. The human P. malariae is indistinguishable
from P. brasilianum, and P. vivax is indistinguishable from P. simium; P.
brasilianum and P. simium are parasitic to New World monkeys. The human P.
vivax-like is indistinguishable from P. simiovale, a parasite of Old World
macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are
evolutionarily recent human parasites, the first two at least acquired only
within the last several thousand years, and perhaps within the last few
hundred years, after the expansion of human populations in South America
following the European colonizations. We estimate the rate of evolution of
the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year.
The divergence between the P. falciparum and P. reichenowi lineages is
accordingly dated 8.9 Myr ago. The divergence between the three lineages
leading to the human parasites is very ancient, about 100 Myr old between
P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between
P. falciparum and the other two.
相似文献
27.
Arvind Kumar Bhatt Tek Chand Bhalla Hari Om Agrawal N. Sharma 《Letters in applied microbiology》1992,15(1):1-4
An extracellular chitosanase produced by Rhodotorula gracilis CFR-1 that catalyses a limited degradation of chitosan with no detectable generation of glucosamine or reducing groups was identified. Ultracentrifugation, polyacrylamide gel electrophoresis and gel permeation studies suggest that chitosan of average molecular mass 36000 Da was reduced by the enzymic catalysis to nearly one-fourth this size without further hydrolysis of the products. The enzyme, produced constitutively by this yeast, was partially purified and some of its properties were studied. 相似文献
28.
29.
The effects of P2X7 receptor antagonists on the formation and function of human osteoclasts in vitro
Agrawal A Buckley KA Bowers K Furber M Gallagher JA Gartland A 《Purinergic signalling》2010,6(3):307-315
The P2X7 receptor (P2X7R) has been implicated in the process of multinucleation and cell fusion. We have previously demonstrated
that blockade of P2X7Rs on osteoclast precursors using a blocking antibody inhibited multinucleated osteoclast formation in
vitro, but that P2X7R KO mice maintain the ability to form multinucleated osteoclasts. This apparent contradiction of the
role the P2X7R plays in multinucleation has prompted us to examine the effect of the most commonly used and recently available
P2X7R antagonists on osteoclast formation and function. When added to recombinant RANKL and M-CSF human blood monocytes cultures,
all but one compound, decreased the formation and function of multinucleated TRAP-positive osteoclasts in a concentration-dependent
manner. These data provide further evidence for the role of the P2X7R in the formation of functional human multinucleated
osteoclasts and highlight the importance of selection of antagonists for use in long-term experiments. 相似文献
30.