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1.
A novel and conserved salt-induced protein is an important determinant of salt tolerance in yeast. 总被引:32,自引:3,他引:29 下载免费PDF全文
We have isolated a novel yeast gene, HAL1, which upon overexpression improves growth under salt stress. In addition, disruption of this gene decreases salt tolerance. Therefore HAL1 constitutes a rate-limiting determinant for halotolerance. It encodes a polar protein of 32 kDa located in the yeast cytoplasm and unrelated to sequences in data banks. The expression of this gene is increased by high concentrations of either NaCl, KCl or sorbitol. On the other hand, the growth advantage obtained by overexpression of HAL1 is specific for NaCl stress. In cells overexpressing HAL1, sodium toxicity seems to be counteracted by an increased accumulation of potassium. The HAL1 protein could interact with the transport systems which determine intracellular K+ homeostasis. The HAL1 gene and encoded protein are conserved in plants, being induced in these organisms by salt stress and abscisic acid. These results suggest that yeast serves as a convenient model system for the molecular biology of plant salt tolerance. 相似文献
2.
Phospholipid methyltransferase phosphorylation by intact hepatocytes: effect of glucagon 总被引:2,自引:0,他引:2
I Varela I Mérida M Villalba F Vivanco J M Mato 《Biochemical and biophysical research communications》1985,131(1):477-483
We have obtained a rabbit antiserum that specifically immunoprecipitates the 50K and 25K proteins of rat liver phospholipid methyltransferase. Exposure of intact rat hepatocytes preincubated with [32P]phosphate to glucagon induces a time-dependent phosphorylation of the 50K protein of phospholipid methyltransferase. The incorporation of 32P into the 50K protein was only on phosphoserine. These data support the concept that the activation of rat liver phospholipid methyltransferase by glucagon is mediated by phosphorylation of the enzyme. 相似文献
3.
C-terminal deletion analysis of plant plasma membrane H(+)-ATPase: yeast as a model system for solute transport across the plant plasma membrane. 总被引:3,自引:0,他引:3 下载免费PDF全文
The plasma membrane proton pump (H(+)-ATPase) energizes solute uptake by secondary transporters. Wild-type Arabidopsis plasma membrane H(+)-ATPase (AHA2) and truncated H(+)-ATPase lacking 38, 51, 61, 66, 77, 92, 96, and 104 C-terminal amino acids were produced in yeast. All AHA2 species were correctly targeted to the yeast plasma membrane and, in addition, accumulated in internal membranes. Removal of 38 C-terminal residues from AHA2 produced a high-affinity state of plant H(+)-ATPase with a low Km value (0.1 mM) for ATP. Removal of an additional 12 amino acids from the C terminus resulted in a significant increase in molecular activity of the enzyme. There was a close correlation between molecular activity of the various plant H(+)-ATPase species and their ability to complement mutants of the endogenous yeast plasma membrane H(+)-ATPase (pma1). This correlation demonstrates that, at least in this heterologous host, activation of H(+)-ATPase is a prerequisite for proper energization of the plasma membrane. 相似文献
4.
Villalba J. M. Navarro F. Roldán J. M. González-Reyes J. A. Navas P. 《Protoplasma》1994,178(3-4):87-96
Summary Expression of various sugar residues on the plasma membrane of frog (Rana perezi) epidermal cells at different stages of differentiation has been monitored with the use of a battery of HRP-conjugated lectins. In paraffin-embedded tissue, mannose residues (stained by Concanavalin A) were detected at the keratinocyte cell surface in all epidermal strata. However,Lens culinaris agglutinin (LCA), also specific for mannose, specifically stained the plasma membrane of cells from the stratum germinativum. Expression of N-acetyl-glucosamine (GlcNAc), labelled with wheat germ agglutinin (WGA), was maximum at the cell surface of basal cells and progressively decreased through the stratum spinosum. Galactose (Gal) and N-acetyl-galactosamine (GalNAc) residues, labelled withGriffonia simplicifolia I (GS I) andGlycine max (SBA) agglutinins, respectively, were expressed according to the degree of differentiation in amphibian epidermal cells. Sialic acid-containing glycoproteins, labelled withLimax flavus agglutinin (LFA), were found in the outermost plasma membrane of the replacement cell layer and stratum corneum. Glycoproteins responsible for the observed lectin-binding patterns have been identified by staining on nitrocellulose filters after electrophoresis of solubilized plasma membrane fractions and Western blotting. Changes at the level of glycosylation of plasma membrane glycoproteins as epidermal cells differentiate are discussed on the basis of a progressive addition of Gal residues. Integral membrane proteins have been solubilized with the non-denaturing detergent CHAPS and glycoproteins containing terminal Gal residues, that are expressed according to the degree of differentiation in frog epidermis, have been partially purified by affinity chromatography on a GS I-Sepharose 4 B column. The purified fraction was composed by four acidic glycoproteins with isoelectric points between 4.6 and 5.2 and, in SDS-gels gave five major protein bands with approximate molecular weights of 148, 140, 102, 60, and 52 kDa in SDS-gels. The 102 and 52 kDa bands correspond to the a and subunits of amphibian epidermal Na+,K+-ATPase as demonstrated by specific staining with a polyclonal antibody against the catalytic subunit of pig kidney proton pump and staining with lectins GS I, GS II, and WGA. Possible relationships between higher molecular weight proteins and the constituents of intramembranous particles from the outermost plasma membranes of the replacement cell layer and the stratum corneum are also discussed.Abbreviations BSA
bovine serum albumin
- CHAPS
(3-[(cholamidopropyl) dimethyl-ammonio] 1-propanesulfonate)
- Con A
Canavalia ensiformis agglutinin
- DTT
dithiothreitol
- Gal
galactose
- GalNAc
N-acetyl-D-galactosamine
- GlcNAc
N-acetyl-D-glucosamine
- GS I
Griffonia simplicifolia agglutinin I
- GS II
Griffonia simplicifolia agglutinin II
- HRP
horseradish peroxidase
- LFA
Limax flavus agglutinin
- LCA
Lens culinaris agglutinin
- NDPAGIF
non-denaturing polyacrylamide gel isoelectric focusing
- PAGE
polyacrylamide gel electrophoresis
- PAP
peroxidase-antiperoxidase
- PBS
phosphate buffered saline
- PMSF
phenyl methyl sulphonyl fluoride
- RCL
replacement cell layer
- SBA
soybean agglutinin (Glycine max)
- SB
stratum basal
- SDS
sodium dodecyl sulphate
- SG
stratum granulosum
- SS
stratum spinosum
- UEA I
Ulex europaeus agglutinin I
- WGA
wheat germ (Triticum vulgaris) agglutinin 相似文献
5.
Lone Baunsgaard Kees Venema Kristian B. Axelsen José Manuel Villalba Annikki Welling Bernd Wollenweber Michael G. Palmgren 《The Plant journal : for cell and molecular biology》1996,10(3):451-458
Transport across the plasma membrane is driven by an electrochemical gradient of H+ ions generated by the plasma membrane proton pump (H+ -ATPase). Random mutants of Arabidopsis H+ -ATPase AHA1 were isolated by phenotypic selection of growth of transformed yeast cells in the absence of endogenous yeast H+ -ATPase (PMA1). A Trp-874-Leu substitution as well as a Trp-874 to Lys-935 deletion in the hydrophilic C-terminal domain of AHA1 conferred growth of yeast cells devoid of PMA1. A Trp-874-Phe substitution in AHA1 was produced by site-directed mutagenesis. The modified enzymes hydrolyzed ATP at 200–500% of wild-type level, had a sixfold increase in affinity for ATP (from 1.2 to 0.2 mM; pH 7.0), and had the acidic pH optimum shifted towards neutral pH. AHA1 did not contribute significantly to H+ extrusion by transformed yeast cells. The different species of aha1, however, displayed marked differences in initial rates of net H+ extrusion and in their ability to sustain an electrochemical H+ gradient. These results provide evidence that Trp-874 plays an important role in auto-inhibition of the plant H+ -ATPase and may be involved in controlling the degree of coupling between ATP hydrolysis and H+ pumping. Finally, these results demonstrate the usefulness of yeast as a generalized screening tool for isolating regulatory mutants of plants transporters. 相似文献
6.
J. C. Rodríguez-Aguilera F. Navarro A. Arroyo F. J. Alcaín J. M. Villalba P. Navas 《Protoplasma》1995,184(1-4):229-232
Summary Ascorbate is stabilized in the presence of HL-60 cells. Our results showed that cAMP derivatives and agents that increase cAMP stimulate the ability of HL-60 cells to stabilize ascorbate. On the other hand, tunicamycin, a glycosilation-interfering agent, inhibited this ability. The ascorbate stabilization in the presence of HL-60 cells has been questioned as a simple chemical effect. Further properties and controls about the enzymatic nature of this stabilization are described and discussed. This data, together with hormonal regulation, support the hypothesis that an enzymatic redox system located at the plasma membrane is responsible of the extracellular ascorbate stabilization by HL-60 cells.Abbreviations AFR
ascorbate free radicals
- FCS
fetal calf serum
- Sp-cAMPS
Sp-cyclic adenosine monophosphothionate
- Rp-cAMPS
Rp-cyclic adenosine monophosphothionate 相似文献
7.
8.
9.
Ecosystems - In this study, we identify the main modes of variability of the Normalized Difference Vegetation Index (NDVI) and their relationships with precipitation and temperature variations... 相似文献
10.
Chamaida Plasencia Dora Pascual-Salcedo Sara García-Carazo Leticia Lojo Laura Nu?o Alejandro Villalba Diana Peiteado Florencia Arribas Jesus Díez Maria Teresa López-Casla Emilio Martín-Mola Alejandro Balsa 《Arthritis research & therapy》2013,15(4):R79