首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   250篇
  免费   18篇
  2023年   1篇
  2022年   8篇
  2021年   16篇
  2020年   6篇
  2019年   6篇
  2018年   11篇
  2017年   16篇
  2016年   12篇
  2015年   16篇
  2014年   16篇
  2013年   21篇
  2012年   22篇
  2011年   12篇
  2010年   7篇
  2009年   6篇
  2008年   10篇
  2007年   16篇
  2006年   10篇
  2005年   10篇
  2004年   8篇
  2003年   10篇
  2002年   4篇
  2001年   4篇
  2000年   5篇
  1999年   4篇
  1995年   1篇
  1993年   2篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1986年   2篇
  1983年   1篇
  1981年   1篇
  1968年   1篇
排序方式: 共有268条查询结果,搜索用时 31 毫秒
21.
Adult-onset type II citrullinemia (CTLN2) is characterized by a liver-specific argininosuccinate synthetase deficiency caused by a deficiency of the citrin protein encoded by the SLC25A13 gene. Until now, however, no SLC25A13 mutations have been reported in children with liver diseases. We described three infants who presented as neonates with intrahepatic cholestasis associated with hypermethioninemia or hypergalactosemia detected by neonatal mass screening. DNA analyses of SLC25A13 revealed that one patient was a compound heterozygote for the 851de14 and IVS11+IG-->A mutations and two patients (siblings) were homozygotes for the IVS11+lG-->A mutation. These results suggested that there may be a variety of liver diseases related to CTLN2 in children.  相似文献   
22.
Cloning of the Microcystis aeruginosa M228 lectin (MAL) gene   总被引:3,自引:0,他引:3  
We have cloned and characterized the gene encoding Microcystis aeruginosa (strain M228) lectin (MAL). The gene contains 1551 nucleotides and an open reading frame for a protein of 517 amino acids with a predicted molecular weight of 55,159 Da. The carboxy-terminal region of MAL has three tandemly repeated homologous domains composed of 61 amino acids. These regions show similarity to the corresponding regions of the alpha-amylase of Clostridium beijerinckii (23% identity). The mal gene lies adjacent to an ORF that display homology to cytochrome P-450 and polyketide synthase. Southern hybridization showed that the genomic DNA of the strain M228 contained, in addition to MAL gene (mal), at least two other mal like gene.  相似文献   
23.
The gene encoding an FMN-dependent NADH azoreductase, AzrG, from thermophilic Geobacillus stearothermophilus was cloned and functionally expressed in recombinant Escherichia coli. Purified recombinant AzrG is a homodimer of 23 kDa and bore FMN as a flavin cofactor. The optimal temperature of AzrG was 85 °C for the degradation of Methyl Red (MR). AzrG remained active for 1 h at 65 °C and for 1 month at 30 °C, demonstrating both superior thermostability and long-term stability of the enzyme. AzrG efficiently decolorized MR, Ethyl Red at 30 °C. Furthermore, the enzyme exhibited a wide-range of degrading activity towards several tenacious azo dyes, such as Acid Red 88, Orange I, and Congo Red. These results suggested the sustainable utilization of G. stearothermophilus as an azo-degrading strain for AzrG carrying whole-cell wastewater treatments for azo pollutants under high temperature conditions.  相似文献   
24.
The change in carotenoid-based bacterial color from yellow to red can be applied to whole-cell biosensors. We generated several green mutants to emphasize the color change in such biosensors. The blue-green crtI-deleted mutant, Rhodopseudomonas palustris no.711, accumulated the colorless carotenoid precursor, phytoene. Green Rhodovulum sulfidophilum M31 accumulated neurosporene, a downstream product of phytoene. Another green mutant, Rhodobacter sphaeroides Ga, accumulated neurosporene and chloroxanthin, which are both downstream products of phytoene. All green mutants accumulated bacteriochlorophyll a. Photosynthetic membrane obtained from the green mutants all exhibited decreased absorption of wavelength range at 510–570 nm. Therefore, these indicate that the greenish bacterial colors were mainly caused by the existence of bacteriochlorophyll a and the changes in carotenoid composition in photosynthetic membrane. The colors of the green mutants and their wild-type strains were plotted in the CIE-L*a*b* color space, and the color difference (ΔE*ab) values between a green mutant and its wild type were calculated. ΔE*ab values were higher in the green mutants than in Rdv. sulfidophilum CDM2, the yellowish host strain of reported biosensors. These data indicate that change in bacterial color from green to red is more distinguishable than that from yellow to red as a reporter signal of carotenoid-based whole-cell biosensors.  相似文献   
25.
We previously reported the protection from myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) by the adoptive transfer of genetically modified embryonic stem cell-derived dendritic cells (ES-DC) presenting MOG peptide in the context of MHC class II molecules and simultaneously expressing TRAIL (ES-DC-TRAIL/MOG). In the present study, we found the severity of EAE induced by another myelin autoantigen, myelin basic protein, was also decreased after treatment with ES-DC-TRAIL/MOG. This preventive effect diminished, if the function of CD4(+)CD25(+) regulatory T cells (Treg) was abrogated by the injection of anti-CD25 mAb into mice before treatment with ES-DC-TRAIL/MOG. The adoptive transfer of CD4(+)CD25(+) T cells from ES-DC-TRAIL/MOG-treated mice protected the recipient mice from MOG- or myelin basic protein-induced EAE. The number of Foxp3(+) cells increased in the spinal cords of mice treated with ES-DC-TRAIL/MOG. In vitro experiments showed that TRAIL expressed in genetically modified ES-DC and also in LPS-stimulated splenic macrophages had a capacity to augment the proliferation of CD4(+)CD25(+) T cells. These results suggest that the prevention of EAE by treatment with ES-DC-TRAIL/MOG is mediated, at least in part, by MOG-reactive CD4(+)CD25(+) Treg propagated by ES-DC-TRAIL/MOG. For the treatment of organ-specific autoimmune diseases, induction of Treg reactive to the organ-specific autoantigens by the transfer of DC-presenting Ags and simultaneously overexpressing TRAIL therefore appears to be a promising strategy.  相似文献   
26.
Previously, bioassay-guided separation led us to isolate eleven novel steroidal alkaloids named cortistatins from the marine sponge Corticium simplex. These cortistatins were classified into three types based on the chemical structure of the side chain part, that is, isoquinoline, N-methyl piperidine or 3-methylpyridine units. From the structure-activity relationship study, the isoquinoline unit in the side chain was found to be crucial for the anti-angiogenic activity of cortistatins. Cortistatin A (1) showed cytostatic growth-inhibitory activity against human umbilical vein endothelial cells (HUVECs). Cortistatin A (1) also inhibited VEGF-induced migration of HUVECs and bFGF-induced tubular formation. Although cortistatin A (1) showed no effect on VEGF-induced phosphorylation of ERK1/2 and p38, which are one of the signaling pathways for migration and tubular formation, the phosphorylation of the unidentified 110kDa protein in HUVECs was inhibited by the treatment with cortistatin A.  相似文献   
27.
Endogenous opioid peptides consist of a conserved amino acid residue of Phe(3) and Phe(4), although their binding modes for opioid receptors have not been elucidated in detail. Endomorphin-2, which is highly selective and specific for the mu opioid receptor, possesses two Phe residues at the consecutive positions 3 and 4. In order to clarify the role of Phe(3) and Phe(4) in binding to the mu receptor, we synthesized a series of analogs in which Phe(3) and Phe(4) were replaced by various amino acids. It was found that the aromaticity of the Phe-beta-phenyl groups of Phe(3) and Phe(4) is a principal determinant of how strongly it binds to the receptor, although better molecular hydrophobicity reinforces the activity. The receptor binding subsites of Phe(3) and Phe(4) of endomorphin-2 were found to exhibit different structural requirements. The results suggest that [Trp(3)]endomorphin-2 (native endomorphin-1) and endomorphin-2 bind to different receptor subclasses.  相似文献   
28.
Three L-rhamnose-binding egg lectins, TBL1, TBL2 and TBL3, were isolated from the eggs of the Far East dace Tribolodon brandti by a combination of affinity chromatography on L-rhamnose-Sepharose 6B gel and reversed-phase HPLC. L-rhamnose is a common inhibitor of the purified lectins and strongly inhibited the hemagglutinating activity of TBL2 and TBL3, but less weakly that of TBL1. L-arabinose, which has the same hydroxyl group orientation at C2 and C4 as L-rhamnose, and D-galactose showed no inhibitory activity against TBL1 but showed weak inhibitory activity against TBL2 and TBL3. The open reading frames of the cDNAs of TBL1, TBL2 and TBL3 encoded for mature proteins of 207, 189, and 293 amino acid residues, respectively. A BLAST homology search showed that the TBLs have about 40% homology to the carbohydrate recognition domains of rhamnose-binding lectins in salmonid eggs. The tandem repeated domains present in TBL1, TBL2 and TBL3 were two, two and three, respectively. TBL2 was exclusively expressed in ovary, while TBL1 and TBL3 were expressed mainly in ovary and weakly in various tissues including gill, heart, kidney, liver, spleen and testis.  相似文献   
29.
30.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号