全文获取类型
收费全文 | 158篇 |
免费 | 13篇 |
出版年
2021年 | 1篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 11篇 |
2013年 | 6篇 |
2012年 | 12篇 |
2011年 | 6篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 2篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 18篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有171条查询结果,搜索用时 187 毫秒
1.
Low‐Overpotential Electrocatalytic Water Splitting with Noble‐Metal‐Free Nanoparticles Supported in a sp3 N‐Rich Flexible COF 下载免费PDF全文
Dinesh Mullangi Vishal Dhavale Sorout Shalini Shyamapada Nandi Sean Collins Tom Woo Sreekumar Kurungot Ramanathan Vaidhyanathan 《Liver Transplantation》2016,6(13)
Covalent organic frameworks (COFs) are crystalline organic polymers with tunable structures. Here, a COF is prepared using building units with highly flexible tetrahedral sp3 nitrogens. This flexibility gives rise to structural changes which generate mesopores capable of confining very small (<2 nm sized) non‐noble‐metal‐based nanoparticles (NPs). This nanocomposite shows exceptional activity toward the oxygen‐evolution reaction from alkaline water with an overpotential of 258 mV at a current density of 10 mA cm?2. The overpotential observed in the COF‐nanoparticle system is the best in class, and is close to the current record of ≈200 mV for any noble‐metal‐free electrocatalytic water splitting system—the Fe–Co–Ni metal‐oxide‐film system. Also, it possesses outstanding kinetics (Tafel slope of 38.9 mV dec?1) for the reaction. The COF is able to stabilize such small‐sized NP in the absence of any capping agent because of the COF–Ni(OH)2 interactions arising from the N‐rich backbone of the COF. Density‐functional‐theory modeling of the interaction between the hexagonal Ni(OH)2 nanosheets and the COF shows that in the most favorable configuration the Ni(OH)2 nanosheets are sandwiched between the sp3 nitrogens of the adjacent COF layers and this can be crucial to maximizing their synergistic interactions. 相似文献
2.
Chlorpyrifos is a commonly used organophosphate pesticide. Its extensive use and associated serious soil and water contamination have gained increasing environmental concern. Biodegradation is a promising way to remediate chlorpyrifos contamination. There are many reports on various chlorpyrifos degrading microorganisms, but only a few on biodegradation of chlorpyrifos by consortia. Hence, the present study attempted to assemble a novel bacterial consortium C5 for the biodegradation of chlorpyrifos. The 16S rRNA gene-based molecular analysis revealed that the bacterial consortium consisted of Staphylococcus warneri CPI 2, Pseudomonas putida CPI 9 and Stenotrophomonas maltophilia CPI 15. Optimization of chlorpyrifos degradation by the consortium C5, using a Box–Behnken design, was carried out taking into account four important variables: temperature, pH, the initial concentration of chlorpyrifos and time of incubation. C5 is capable of giving 90% degradation of chlorpyrifos (125 ppm) in 8 days of incubation under optimized conditions of pH (7) and temperature (30°C). Growth curve and degradation study under optimized conditions confirmed that consortium could improve the biodegradation potential. From these results, we conclude that the novel consortium C5 of three species can be used to eliminate chlorpyrifos from various environmental compartments and can be implemented in bioreactors in a cost-effective, safe and environmentally friendly manner. 相似文献
3.
In vitro morphogenic response of nodal explants from six cultivars of Philodendron viz, blue mistic, painted lady, pink prince, pluto, royal queen and green emperor was studied. Frequency and number of shoot formation depend on the cultivars and concentration of BAP. High frequency and number of shoot formation were obtained w hen the nodal explants were cultured in Nitsch medium supplemented with BAP (6.8-11.8 microM), sucrose (2%) and agar (0.45%), initially in the dark for 8-10 weeks followed by 16 hr photoperiod. Regenerated shoots were rooted on medium without growth regulators. After two weeks of hardening, rooted and rootless shoots were established in the soil with more than 90 and 65% survival rates respectively, while the unhardened plantlets showed a much lower percentage (20%) establishment. A standard protocol for the rapid multiplication of Philodendron is presented. 相似文献
4.
Palmitoleate is not present in lipid A isolated from Escherichia coli grown at 30 degrees C or higher, but it comprises approximately 11% of the fatty acyl chains of lipid A in cells grown at 12 degrees C. The appearance of palmitoleate at 12 degrees C is accompanied by a decline in laurate from approximately 18% to approximately 5.5%. We now report that wild-type E. coli shifted from 30 degrees C to 12 degrees C acquire a novel palmitoleoyl-acyl carrier protein (ACP)-dependent acyltransferase that acts on the key lipid A precursor Kdo2-lipid IVA. The palmitoleoyl transferase is induced more than 30-fold upon cold shock, as judged by assaying extracts of cells shifted to 12 degrees C. The induced activity is maximal after 2 h of cold shock, and then gradually declines but does not disappear. Strains harboring an insertion mutation in the lpxL(htrB) gene, which encodes the enzyme that normally transfers laurate from lauroyl-ACP to Kdo2-lipid IVA (Clementz, T., Bednarski, J. J., and Raetz, C. R. H. (1996) J. Biol. Chem. 271, 12095-12102) are not defective in the cold-induced palmitoleoyl transferase. Recently, a gene displaying 54% identity and 73% similarity at the protein level to lpxL was found in the genome of E. coli. This lpxL homologue, designated lpxP, encodes the cold shock-induced palmitoleoyl transferase. Extracts of cells containing lpxP on the multicopy plasmid pSK57 exhibit a 10-fold increase in the specific activity of the cold-induced palmitoleoyl transferase compared with cells lacking the plasmid. The elevated specific activity of the palmitoleoyl transferase under conditions of cold shock is attributed to greatly increased levels of lpxP mRNA. The replacement of laurate with palmitoleate in lipid A may reflect the desirability of maintaining the optimal outer membrane fluidity at 12 degrees C. 相似文献
5.
Balagopal P Pandey M Chandramohan K Somanathan T Kumar A 《World journal of surgical oncology》2003,1(1):4
Background
Choriocarcinoma is an aggressive neoplasm arising in the body of the uterus. The disease normally spreads to lung and brain. 相似文献6.
Phosphorylation of simian virus 40 T antigen on Thr 124 selectively promotes double-hexamer formation on subfragments of the viral core origin 下载免费PDF全文
Cell cycle-dependent phosphorylation of simian virus 40 (SV40) large tumor antigen (T-ag) on threonine 124 is essential for the initiation of viral DNA replication. A T-ag molecule containing a Thr-->Ala substitution at this position (T124A) was previously shown to bind to the SV40 core origin but to be defective in DNA unwinding and initiation of DNA replication. However, exactly what step in the initiation process is defective as a result of the T124A mutation has not been established. Therefore, to better understand the control of SV40 replication, we have reinvestigated the assembly of T124A molecules on the SV40 origin. Herein it is demonstrated that hexamer formation is unaffected by the phosphorylation state of Thr 124. In contrast, T124A molecules are defective in double-hexamer assembly on subfragments of the core origin containing single assembly units. We also report that T124A molecules are inhibitors of T-ag double hexamer formation. These and related studies indicate that phosphorylation of T-ag on Thr 124 is a necessary step for completing the assembly of functional double hexamers on the SV40 origin. The implications of these studies for the cell cycle control of SV40 DNA replication are discussed. 相似文献
7.
Assembly of T-Antigen Double Hexamers on the Simian Virus 40 Core Origin Requires Only a Subset of the Available Binding Sites 总被引:9,自引:1,他引:8
Woo S. Joo Henry Y. Kim John D. Purviance K. R. Sreekumar Peter A. Bullock 《Molecular and cellular biology》1998,18(5):2677-2687
Initiation of simian virus 40 (SV40) DNA replication is dependent upon the assembly of two T-antigen (T-ag) hexamers on the SV40 core origin. To further define the oligomerization mechanism, the pentanucleotide requirements for T-ag assembly were investigated. Here, we demonstrate that individual pentanucleotides support hexamer formation, while particular pairs of pentanucleotides suffice for the assembly of T-ag double hexamers. Related studies demonstrate that T-ag double hexamers formed on “active pairs” of pentanucleotides catalyze a set of previously described structural distortions within the core origin. For the four-pentanucleotide-containing wild-type SV40 core origin, footprinting experiments indicate that T-ag double hexamers prefer to bind to pentanucleotides 1 and 3. Collectively, these experiments demonstrate that only two of the four pentanucleotides in the core origin are necessary for T-ag assembly and the induction of structural changes in the core origin. Since all four pentanucleotides in the wild-type origin are necessary for extensive DNA unwinding, we concluded that the second pair of pentanucleotides is required at a step subsequent to the initial assembly process. 相似文献
8.
9.
Julie Baby Reeta Subramaniam Mani Swapna Susan Abraham Asha T. Thankappan Prasad Madhavan Pillai Ashwini Manoor Anand Shampur Narayan Madhusudana Jayachandran Ramachandran Sachin Sreekumar 《PLoS neglected tropical diseases》2015,9(7)
Background
Rabies is a fatal encephalitis caused by viruses belonging to the genus Lyssavirus of the family Rhabdoviridae. It is a viral disease primarily affecting mammals, though all warm blooded animals are susceptible. Experimental rabies virus infection in birds has been reported, but naturally occurring infection of birds has been documented very rarely.Principal Findings
The carcass of a domestic fowl (Gallus domesticus), which had been bitten by a stray dog one month back, was brought to the rabies diagnostic laboratory. A necropsy was performed and the brain tissue obtained was subjected to laboratory tests for rabies. The brain tissue was positive for rabies viral antigens by fluorescent antibody test (FAT) confirming a diagnosis of rabies. Phylogenetic analysis based on nucleoprotein gene sequencing revealed that the rabies virus strain from the domestic fowl belonged to a distinct and relatively rare Indian subcontinent lineage.Significance
This case of naturally acquired rabies infection in a bird species, Gallus domesticus, being reported for the first time in India, was identified from an area which has a significant stray dog population and is highly endemic for canine rabies. It indicates that spill over of infection even to an unusual host is possible in highly endemic areas. Lack of any clinical signs, and fewer opportunities for diagnostic laboratory testing of suspected rabies in birds, may be the reason for disease in these species being undiagnosed and probably under-reported. Butchering and handling of rabies virus- infected poultry may pose a potential exposure risk. 相似文献10.