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51.
J. N. J. Philipsen J. E. de Vries J. Samallo C. van Dijk A. C. Arnberg G. AB 《Journal of molecular evolution》1989,28(3):185-190
Summary An allele giving rise to a polymorphism within the 3 part of the chicken vitellogenin gene was cloned, sequenced, and compared to the previously cloned allele. The polymorphism is formed by a perfect copy of 343 bp from intron 32 in tandem array with a perfect copy of 244 bp from intron 33; this 587-bp element is inserted in a head-to-tail arrangement in intron 33. We propose a mechanism in which an unequal crossing-over resulted in a vitellogenin gene with two exons 33, one of which was subsequently deleted. Thus, intron 33 was enlarged by the tandem repeats without affecting the protein-encoding sequence of the gene. At the boundaries of the repeated elements, two short direct repeats are found that resemble the recombination signals of immunoglobulin genes. They may have had a key role in the formation of the new allele. 相似文献
52.
Initiation and characterization of a diploid cell line from larval tissues ofAedes dorsalis (Meigen)
Barbara E. Cahoon James L. Hardy William C. Reeves 《In vitro cellular & developmental biology. Plant》1978,14(3):255-260
Summary Mosquito cell cultures were initiated from the minced tissues of newly hatchedAedes dorsalis (Meigen) larvae. Continuous cell division occurred only after an adaptive period of approximately 6 months. Optimal growth
of the cells required a relatively low pH of 6.5. Karyological studies showed that the cells have remained diploid (2n=6)
for 60 serial passages and that the cultures are free of contaminating cells. The cultures also were shown to be free of bacteria
(includingMycoplasma), fungi and virions. Subpopulations (strains) of the original parental cultures have been selected and characterized on the
basis of morphology, karyology, growth rate and monolayer formation.
These studies were supported in part by funds from the Office of Naval Research, by Research Grant AI03028 from the National
Institute of Allergy and Infectious Diseases, and by General Research Support Grant I-SO1-FR-05441 from the National Institutes
of Health, U.S. Department of Health, Education and Welfare. 相似文献
53.
Salvador Casares Eiso AB Henk Eshuis Obdulio Lopez-Mayorga Nico AJ van Nuland Francisco Conejero-Lara 《BMC structural biology》2007,7(1):22
Background
SH3 domains are small protein modules of 60–85 amino acids that bind to short proline-rich sequences with moderate-to-low affinity and specificity. Interactions with SH3 domains play a crucial role in regulation of many cellular processes (some are related to cancer and AIDS) and have thus been interesting targets in drug design. The decapeptide APSYSPPPPP (p41) binds with relatively high affinity to the SH3 domain of the Abl tyrosine kinase (Abl-SH3), while it has a 100 times lower affinity for the α-spectrin SH3 domain (Spc-SH3). 相似文献54.
55.
Paul S Gable K Beaudoin F Cahoon E Jaworski J Napier JA Dunn TM 《The Journal of biological chemistry》2006,281(14):9018-9029
Several 3-keto-synthases have been studied, including the soluble fatty acid synthases, those involved in polyketide synthesis, and the FAE1-like 3-ketoacyl-CoA synthases. All of these condensing enzymes have a common ancestor and an enzymatic mechanism that involves a catalytic triad consisting of Cys, His, and His/Asn. In contrast to the FAE1-like family of enzymes that mediate plant microsomal fatty acid elongation, the condensation step of elongation in animals and in fungi appears to be mediated by the Elop homologs. Curiously these proteins bear no resemblance to the well characterized 3-keto-synthases. There are three ELO genes in yeast that encode the homologous Elo1p, Elo2p, and Elo3p proteins. Elo2p and Elo3p are required for synthesis of the very long-chain fatty acids, and mutants lacking both Elo2p and Elo3p are inviable confirming that the very long-chain fatty acids are essential for cellular functions. In this study we show that heterologous expression of several Arabidopsis FAE1-like genes rescues the lethality of an elo2Deltaelo3Delta yeast mutant. We further demonstrate that FAE1 acts in conjunction with the 3-keto and trans-2,3-enoyl reductases of the elongase system. These studies indicate that even though the plant-specific FAE1 family of condensing enzymes evolved independently of the Elop family of condensing enzymes, they utilize the same reductases and presumably dehydratase that the Elop proteins rely upon. 相似文献
56.
Phosphorus and carbohydrate limitation of fecal coliform and fecal enterococcus within tidal creek sediments 总被引:2,自引:0,他引:2
Aquatic sediments can be a significant reservoir of bacterial indicators of fecal contamination at levels higher than the
waters above them. Several environmental factors have been identified that can enhance the role of sediments as a reservoir
for enteric pathogens, including carbon and/or phosphorus availability. In order to investigate the influence of these and
other environmental factors on sediment fecal bacteria populations, sediment samples were collected from a coastal watershed
in southeastern North Carolina and analyzed for fecal coliform and fecal enterococcus using a modified membrane filtration
technique. Measurements of sediment phosphorus, sediment carbohydrate, and environmental factors were made and relationships
with bacteria concentrations were assessed. These observations were accompanied by an experimental laboratory manipulation
of phosphorus and carbohydrate and their effects on sediment-associated fecal coliform and enterococcus. Field results suggested
that sediment-associated indicator bacteria were not limited by sediment phosphorus or carbohydrate. Experimental results
suggested that sediment-associated fecal bacteria were more frequently limited by bioavailable carbohydrate. Sediment phosphorus
was limiting for fecal enterococcus only where sediment P was initially low (<31 μg P g−1). A strong positive response by sediment fecal coliform concentrations to recent (24 h) precipitation was evidence that stormwater
runoff delivers fecal bacteria loadings that are only partly measurable by conventional water sampling schemes, and by driving
sediment and sediment P-loading plays a significant role in enhancing aquatic sediments as reservoirs for fecal microbes. 相似文献
57.
Theo S Plantinga Jaap Fransen Nozomi Takahashi Rinke Stienstra Piet L van Riel Wim B van den Berg Mihai G Netea Leo AB Joosten 《Arthritis research & therapy》2010,12(1):1-10
Introduction
We have previously demonstrated that ex vivo inhibition of costimulatory molecules on antigen-pulsed dendritic cells (DCs) can be useful for induction of antigen-specific immune deviation and suppression of autoimmune arthritis in the collagen induced arthritis (CIA) model. The current study evaluated a practical method of immune modulation through temporary systemic inhibition of the costimulatory molecule CD40.Methods
Mice with collagen II (CII)-induced arthritis (CIA) were administered siRNA targeting the CD40 molecule. Therapeutic effects were evaluated by clinical symptoms, histopathology, Ag-specific T cell and B cell immune responses.Results
Systemic administration of CD40-targeting siRNA can inhibit antigen-specific T cell response to collagen II, as well as prevent pathogenesis of disease in both a pre- and post-immunization manner in the CIA model. Disease amelioration was associated with suppression of Th1 cytokines, attenuation of antibody production, and upregulation of T regulatory cells.Conclusions
These studies support the feasibility of transient gene silencing at a systemic level as a mechanism of resetting autoreactive immunity. 相似文献58.
Masakazu Kobayashi Eiso AB Alexander M. J. J. Bonvin Gregg Siegal 《The Journal of biological chemistry》2010,285(13):10087-10097
BRCA1 C-terminal domain (BRCT)-containing proteins are found widely throughout the animal and bacteria kingdoms where they are exclusively involved in cell cycle regulation and DNA metabolism. Whereas most BRCT domains are involved in protein-protein interactions, a small subset has bona fide DNA binding activity. Here, we present the solution structure of the BRCT region of the large subunit of replication factor C bound to DNA and a model of the structure-specific complex with 5′-phosphorylated double-stranded DNA. The replication factor C BRCT domain possesses a large basic patch on one face, which includes residues that are structurally conserved and ligate the phosphate in phosphopeptide binding BRCT domains. An extra α-helix at the N terminus, which is required for DNA binding, inserts into the major groove and makes extensive contacts to the DNA backbone. The model of the protein-DNA complex suggests 5′-phosphate recognition by the BRCT domains of bacterial NAD+-dependent ligases and a nonclamp loading role for the replication factor C complex in DNA transactions. 相似文献
59.
Background
The National Institute of Allergy and Infectious Diseases has launched the HIV-1 Human Protein Interaction Database in an effort to catalogue all published interactions between HIV-1 and human proteins. In order to systematically investigate these interactions functionally and dynamically, we have constructed an HIV-1 human protein interaction network. This network was analyzed for important proteins and processes that are specific for the HIV life-cycle. In order to expose viral strategies, network motif analysis was carried out showing reoccurring patterns in virus-host dynamics. 相似文献60.
Dimorphecolic acid (9-OH-18:2Delta(10)(trans)(,12)(trans)) is the major fatty acid of seeds of Dimorphotheca species. This fatty acid contains structural features that are not typically found in plant fatty acids, including a C-9 hydroxyl group, Delta(10),Delta(12)-conjugated double bonds, and trans-Delta(12) unsaturation. Expressed sequence tag analysis was conducted to determine the biosynthetic origin of dimorphecolic acid. cDNAs for two divergent forms of Delta(12)-oleic acid desaturase, designated DsFAD2-1 and Ds-FAD2-2, were identified among expressed sequence tags generated from developing Dimorphotheca sinuata seeds. Expression of DsFAD2-1 in Saccharomyces cerevisiae and soybean somatic embryos resulted in the accumulation of the trans-Delta(12) isomer of linoleic acid (18: 2Delta(9)(cis)(,12)(trans)) rather than the more typical cis-Delta(12) isomer. When co-expressed with DsFAD2-1 in soybean embryos or yeast, DsFAD2-2 converted 18:2Delta(9)(cis)(,12)(trans) into dimorphecolic acid. When DsFAD2-2 was expressed alone in soybean embryos or together with a typical cis-Delta(12)-oleic acid desaturase in yeast, trace amounts of the cis-Delta(12) isomer of dimorphecolic acid (9-OH-18:2Delta(10)(trans,)(12)(cis)) were formed from DsFAD2-2 activity with cis-Delta(12)-linoleic acid [corrected]. These results indicate that DsFAD2-2 catalyzes the conversion of the Delta(9) double bond of linoleic acid into a C-9 hydroxyl group and Delta(10)(trans) double bond and displays a substrate preference for the trans-Delta(12), rather than the cis-Delta(12), isomer of linoleic acid. Overall these data are consistent with a biosynthetic pathway of dimorphecolic acid involving the concerted activities of DsFAD2-1 and DsFAD2-2. The evolution of two divergent Delta(12)-oleic acid desaturases for the biosynthesis of an unusual fatty acid is unprecedented in plants. 相似文献