全文获取类型
收费全文 | 824篇 |
免费 | 42篇 |
国内免费 | 2篇 |
出版年
2023年 | 7篇 |
2022年 | 22篇 |
2021年 | 47篇 |
2020年 | 23篇 |
2019年 | 22篇 |
2018年 | 25篇 |
2017年 | 38篇 |
2016年 | 34篇 |
2015年 | 42篇 |
2014年 | 45篇 |
2013年 | 66篇 |
2012年 | 75篇 |
2011年 | 97篇 |
2010年 | 39篇 |
2009年 | 42篇 |
2008年 | 42篇 |
2007年 | 51篇 |
2006年 | 36篇 |
2005年 | 23篇 |
2004年 | 25篇 |
2003年 | 25篇 |
2002年 | 13篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有868条查询结果,搜索用时 31 毫秒
81.
82.
83.
Nirmal K. Prasad Vaibhav Vindal Vikash Kumar Ashish Kabra Navneet Phogat Manoj Kumar 《Journal of molecular modeling》2011,17(3):533-541
Lignin, a major constituent of plant call wall, is a phenolic heteropolymer. It plays a major role in the development of plants
and their defense mechanism against pathogens. Therefore Lignin biosynthesis is one of the critical metabolic pathways. In
lignin biosynthesis, the Cinnamoyl CoA reductase is a key enzyme which catalyzes the first step in the pathway. Cinnamoyl
CoA reductase provides the substrates which represent the main transitional molecules of lignin biosynthesis pathway, exhibits
a high in vitro kinetic preference for feruloyl CoA. In present study, the three-dimensional model of cinnamoyl CoA reductase was constructed
based on the crystal structure of Grape Dihydroflavonol 4-Reductase. Furthermore, the docking studies were performed to understand
the substrate interactions to the active site of CCR. It showed that residues ARG51, ASN52, ASP54 and ASN58 were involved
in substrate binding. We also suggest that residue ARG51 in CCR is the determinant residue in competitive inhibition of other
substrates. This structural and docking information have prospective implications to understand the mechanism of CCR enzymatic
reaction with feruloyl CoA, however the approach will be applicable in prediction of substrates and engineering 3D structures
of other enzymes as well. 相似文献
84.
Chogle A Bu HF Wang X Brown JB Chou PM Tan XD 《Molecular medicine (Cambridge, Mass.)》2011,17(5-6):502-507
Milk fat globule-EGF factor 8 (MFG-E8) has been shown to play an important role in maintaining the integrity of the intestinal mucosa and to accelerate healing of the mucosa in septic mice. Herein, we (a) analyzed the expression of MFG-E8 in the gut of wild-type (WT) C57BL/6 (MFG-E8(+/+)) mice with and without dextran sulfate sodium (DSS)-induced colitis, (b) characterized the pathological changes in intestinal mucosa of MFG-E8(+/+) and MFG-E8(-/-) mice with DSS-induced colitis and (c) examined the therapeutic role of MFG-E8 in inflammatory bowel disease by using DSS-induced colitis model. Our data documented that there was an increase in colonic and rectal MFG-E8 expression in MFG-E8(+/+) mice during the development of DSS colitis. MFG-E8 levels in both tissues decreased to below baseline during the recovery phase in mice with colitis. Changes in MFG-E8 gene expression correlated to the levels of inflammatory response and crypt-epithelial injury in both colonic and rectal mucosa in MFG-E8(+/+) mice. MFG-E8(-/-)mice developed more severe crypt-epithelial injury than MFG-E8(+/+) mice during exposure to DSS with delayed healing of intestinal epithelium during the recovery phase of DSS colitis. Administration of MFG-E8 during the recovery phase ameliorated colitis and promoted mucosal repair in both MFG-E8(-/-) and MFG-E8(+/+) mice, indicating that lack of MFG-E8 causes increased susceptibility to colitis and delayed mucosal healing. These data suggest that MGF-E8 is an essential protective factor for gut epithelial homeostasis, and exogenous administration of MFG-E8 may represent a novel therapeutic target in inflammatory bowel disease. 相似文献
85.
Shivaji S Pratibha MS Sailaja B Hara Kishore K Singh AK Begum Z Anarasi U Prabagaran SR Reddy GS Srinivas TN 《Extremophiles : life under extreme conditions》2011,15(1):1-22
Three 16S rRNA gene clone libraries (P1L, P4L and P8L) were constructed using three soil samples (P1S, P4S and P8S) collected
near Pindari glacier, Himalayas. The three libraries yielded a total of 703 clones. Actinobacteria, Firmicutes and Proteobacteria were common to the three libraries. In addition to the above P1L and P8L shared the phyla Acidobacteria, Bacteroidetes, Gemmatimonadetes and Planctomycetes. Phyla Chlamydiae, Chlorobi, Chloroflexi, Dictyoglomi, Fibrobacteres, Nitrospirae, Verrucomicrobia, candidate division SPAM and candidate TM7s TM7a phylum were present only in P1L. Rarefaction analysis indicated that the
bacterial diversity in P4S and P8S soil samples was representative of the sample. Principal component analysis (PCA) revealed
that P1S and P8S were different from P4S soil sample. PCA also indicated that arsenic content, pH, Cr and altitude influence
the observed differences in the percentage of specific OTUs in the three 16S rRNA gene clone libraries. The observed bacterial
diversity was similar to that observed for other Himalayan and non-polar cold habitats. A total of 40 strains of bacteria
were isolated from the above three soil samples and based on the morphology 20 bacterial strains were selected for further
characterization. The 20 bacteria belonged to 12 different genera. All the isolates were psychro-, halo- and alkalitolerant.
Amylase and urease activities were detected in majority of the strains but lipase and protease activities were not detected.
Long chain, saturated, unsaturated and branched fatty acids were predominant in the psychrotolerant bacteria. 相似文献
86.
Biological data is often tabular but finding statistically valid connections between entities in a sequence of tables can
be problematic - for example, connecting particular entities in a drug property table to gene properties in a second table,
using a third table associating genes with drugs. Here we present an approach (CRIT) to find connections such as these and
show how it can be applied in a variety of genomic contexts including chemogenomics data. 相似文献
87.
88.
Minimization of the wiring cost of white matter fibers in the human brain appears to be an organizational principle. We investigate this aspect in the human brain using whole brain connectivity networks extracted from high resolution diffusion MRI data of 14 normal volunteers. We specifically address the question of whether brain anatomy determines its connectivity or vice versa. Unlike previous studies we use weighted networks, where connections between cortical nodes are real-valued rather than binary off-on connections. In one set of analyses we found that the connectivity structure of the brain has near optimal wiring cost compared to random networks with the same number of edges, degree distribution and edge weight distribution. A specifically designed minimization routine could not find cheaper wiring without significantly degrading network performance. In another set of analyses we kept the observed brain network topology and connectivity but allowed nodes to freely move on a 3D manifold topologically identical to the brain. An efficient minimization routine was written to find the lowest wiring cost configuration. We found that beginning from any random configuration, the nodes invariably arrange themselves in a configuration with a striking resemblance to the brain. This confirms the widely held but poorly tested claim that wiring economy is a driving principle of the brain. Intriguingly, our results also suggest that the brain mainly optimizes for the most desirable network connectivity, and the observed brain anatomy is merely a result of this optimization. 相似文献
89.
90.