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111.
Kriska T Levchenko VV Korytowski W Atshaves BP Schroeder F Girotti AW 《The Journal of biological chemistry》2006,281(33):23643-23651
Sterol carrier protein-2 (SCP-2) plays a crucial role in the trafficking and metabolism of cholesterol and other lipids in mammalian cells. Lipid hydroperoxides generated under oxidative stress conditions are relatively long-lived intermediates that damage cell membranes and play an important role in redox signaling. We hypothesized that SCP-2-facilitated translocation of lipid hydroperoxides in oxidatively stressed cells might enhance cytolethality if highly sensitive sites are targeted and detoxification capacity is insufficient. We tested this using a clone (SC2A) of rat hepatoma cells that overexpress mature immunodetectable SCP-2. When challenged with liposomal cholesterol-7alpha-hydroperoxide (7alpha-OOH), SC2A cells were found to be much more sensitive to viability loss than vector control (VC) counterparts. Correspondingly, SC2A cells imported [14C]7alpha-OOH more rapidly. The clones were equally sensitive to tert-butyl hydroperoxide, suggesting that the 7alpha-OOH effect was SCP-2-specific. Fluorescence intensity of the probes 2',7'-dichlorofluorescein and C11-BODIPY increased more rapidly in SC2A than VC cells after 7alpha-OOH exposure, consistent with more rapid internalization and oxidative turnover in the former. [14C]7alpha-OOH radioactivity accumulated much faster in SC2A mitochondria than in VC, whereas other subcellular fractions showed little rate difference. In keeping with this, 7alpha-OOH-stressed SC2A cells exhibited a faster loss of mitochondrial membrane potential and development of apoptosis. This is the first reported evidence that peroxidative stress damage can be selectively targeted and exacerbated by an intracellular lipid transfer protein. 相似文献
112.
113.
Kiryushko D Novitskaya V Soroka V Klingelhofer J Lukanidin E Berezin V Bock E 《Molecular and cellular biology》2006,26(9):3625-3638
The S100A4 protein belongs to the S100 family of vertebrate-specific proteins possessing both intra- and extracellular functions. In the nervous system, high levels of S100A4 expression are observed at sites of neurogenesis and lesions, suggesting a role of the protein in neuronal plasticity. Extracellular oligomeric S100A4 is a potent promoter of neurite outgrowth and survival from cultured primary neurons; however, the molecular mechanism of this effect has not been established. Here we demonstrate that oligomeric S100A4 increases the intracellular calcium concentration in primary neurons. We present evidence that both S100A4-induced Ca(2+) signaling and neurite extension require activation of a cascade including a heterotrimeric G protein(s), phosphoinositide-specific phospholipase C, and diacylglycerol-lipase, resulting in Ca(2+) entry via nonselective cation channels and via T- and L-type voltage-gated Ca(2+) channels. We demonstrate that S100A4-induced neurite outgrowth is not mediated by the receptor for advanced glycation end products, a known target for other extracellular S100 proteins. However, S100A4-induced signaling depends on interactions with heparan sulfate proteoglycans at the cell surface. Thus, glycosaminoglycans may act as coreceptors of S100 proteins in neurons. This may provide a mechanism by which S100 proteins could locally regulate neuronal plasticity in connection with brain lesions and neurological disorders. 相似文献
114.
North SJ Koles K Hembd C Morris HR Dell A Panin VM Haslam SM 《Glycoconjugate journal》2006,23(5-6):345-354
With the complete genome sequence of Drosophila melanogaster defined a systematic approach towards understanding the function of glycosylation has become possible. Structural assignment
of the entire Drosophila glycome during specific developmental stages could provide information that would shed further light on the specific roles
of different glycans during development and pinpoint the activity of certain glycosyltransferases and other glycan biosynthetic
genes that otherwise might be missed through genetic analyses. In this paper the major glycoprotein N- and O-glycans of Drosophila embryos are described as part of our initial undertaking to characterize the glycome of Drosophila melanogaster. The N-glycans are dominated by high mannose and paucimannose structures. Minor amounts of mono-, bi- and tri-antennary complex
glycans were observed with GlcNAc and Galβ1–4GlcNAc non-reducing end termini. O-glycans were restricted to the mucin-type
core 1 Galβ1-3GalNAc sequence. 相似文献
115.
116.
Petukhov M Lebedev D Shalguev V Islamov A Kuklin A Lanzov V Isaev-Ivanov V 《Proteins》2006,65(2):296-304
RecA protein is a central enzyme in homologous DNA recombination, repair and other forms of DNA metabolism in bacteria. It functions as a flexible helix-shaped filament bound on stretched single-stranded or double-stranded DNA in the presence of ATP. In this work, we present an atomic level model for conformational transitions of the RecA filament. The model describes small movements of the RecA N-terminal domain due to coordinated rotation of main chain dihedral angles of two amino acid residues (Psi/Lys23 and Phi/Gly24), while maintaining unchanged the RecA intersubunit interface. The model is able to reproduce a wide range of observed helix pitches in transitions between compressed and stretched conformations of the RecA filament. Predictions of the model are in agreement with Small Angle Neutron Scattering (SANS) measurements of the filament helix pitch in RecA::ADP-AlF(4) complex at various salt concentrations. 相似文献
117.
Victor N. Bulyuk Andrey Mukhin Dmitry Kishkinev Vladislav Kosarev 《Journal of Ornithology》2009,150(2):339-350
We studied the effects of weather and the lunar cycle on long-distance nocturnal pre-migratory flights of Reed Warblers (Acrocephalus scirpaceus). Noturnal tape luring was used to capture the birds, and the study was carried out in a habitat atypical of this species
on the Courish Spit (southeastern Baltic) between1999 and 2002. A total of 443 juvenile Reed Warblers were captured during
120 nights of trapping. Based on data on the moult and body condition of the birds, it was possible to identify 163 individuals
as being on post-fledging movements. More than half of the birds (54.0%) were captured at the end of night during the nautical
and civil twilight period; the remaining individuals were caught during the astronomical twilight period and darkest periods
of night. Many birds performed pre-migratory flights in the middle of the night, the period during which a large part of the
moon was visible. We suggest that the increased visibility under the full moon may provide conditions in which Reed Warblers
increase the distance or intensity of nocturnal post-fledging movements. During the entire course of the night, the birds
generally preferred to fly under rainless conditions, limited cloud cover and/or in still air. The birds performed flights
under winds stronger than 2 m s−1 when the wind was blowing along the axis of the spit. We also suggest that the birds generally fly along the spit. We found
a weak but significant relationship between the numbers of Reed Warblers captured during post-fledging movements and the individual
weather parameters and their interaction. Our data suggest that endogenous stimuli rather than weather parameters or lunar
cycle phase determine the decision of Reed Warblers to undertake pre-migratory long-distance flights at night. 相似文献
118.
In this minireview, we examine the ability of modified citrus pectin (MCP), a complex water soluble indigestible polysaccharide obtained from the peel and pulp of citrus fruits and modified by means of high pH and temperature treatment, to affect numerous rate-limiting steps in cancer metastasis. The anti-adhesive properties of MCP as well as its potential for increasing apoptotic responses of tumor cells to chemotherapy by inhibiting galectin-3 anti-apoptotic function are discussed in the light of a potential use of this carbohydrate-based substance in the treatment of multiple human malignancies. 相似文献
119.
120.
Bakhlanova IV Dudkina AV Baitin DM Knight KL Cox MM Lanzov VA 《Molecular microbiology》2010,78(6):1523-1538
The wild-type Escherichia coli RecA protein is a recombinase platform with unrealized recombination potential. We have explored the factors affecting recombination during conjugation with a quantitative assay. Regulatory proteins that affect RecA function have the capacity to increase or decrease recombination frequencies by factors up to sixfold. Autoinhibition by the RecA C-terminus can affect recombination frequency by factors up to fourfold. The greatest changes in recombination frequency measured here are brought about by point mutations in the recA gene. RecA variants can increase recombination frequencies by more than 50-fold. The RecA protein thus possesses an inherently broad functional range. The RecA protein of E. coli (EcRecA) is not optimized for recombination function. Instead, much of the recombination potential of EcRecA is structurally suppressed, probably reflecting cellular requirements. One point mutation in EcRecA with a particularly dramatic effect on recombination frequency, D112R, exhibits an enhanced capacity to load onto SSB-coated ssDNA, overcome the effects of regulatory proteins such as PsiB and RecX, and to pair homologous DNAs. Comparisons of key RecA protein mutants reveal two components to RecA recombination function - filament formation and the inherent DNA pairing activity of the formed filaments. 相似文献