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排序方式: 共有113条查询结果,搜索用时 593 毫秒
31.
IY Petrushanko S Yakushev VA Mitkevich YV Kamanina RH Ziganshin X Meng AA Anashkina A Makhro OD Lopina M Gassmann AA Makarov A Bogdanova 《The Journal of biological chemistry》2012,287(38):32195-32205
Na,K-ATPase is highly sensitive to changes in the redox state, and yet the mechanisms of its redox sensitivity remain unclear. We have explored the possible involvement of S-glutathionylation of the catalytic α subunit in redox-induced responses. For the first time, the presence of S-glutathionylated cysteine residues was shown in the α subunit in duck salt glands, rabbit kidneys, and rat myocardium. Exposure of the Na,K-ATPase to oxidized glutathione (GSSG) resulted in an increase in the number of S-glutathionylated cysteine residues. Increase in S-glutathionylation was associated with dose- and time-dependent suppression of the enzyme function up to its complete inhibition. The enzyme inhibition concurred with S-glutathionylation of the Cys-454, -458, -459, and -244. Upon binding of glutathione to these cysteines, the enzyme was unable to interact with adenine nucleotides. Inhibition of the Na,K-ATPase by GSSG did not occur in the presence of ATP at concentrations above 0.5 mm. Deglutathionylation of the α subunit catalyzed by glutaredoxin or dithiothreitol resulted in restoration of the Na,K-ATPase activity. Oxidation of regulatory cysteines made them inaccessible for glutathionylation but had no profound effect on the enzyme activity. Regulatory S-glutathionylation of the α subunit was induced in rat myocardium in response to hypoxia and was associated with oxidative stress and ATP depletion. S-Glutathionylation was followed by suppression of the Na,K-ATPase activity. The rat α2 isoform was more sensitive to GSSG than the α1 isoform. Our findings imply that regulatory S-glutathionylation of the catalytic subunit plays a key role in the redox-induced regulation of Na,K-ATPase activity. 相似文献
32.
L. I. Kramarova R. Kh. Ziganshin E. N. Gakhova 《Russian Journal of Bioorganic Chemistry》2009,35(5):538-548
Mammalian hibernation is a natural model of tolerance of oragnisms, its tissues and cells to hypometabolism, hypothermia,
hypoxia, bradycardia, and long-term hypophagia. Here, we review recent advances in the isolation and identification of some
natural endogenous regulators from hibernating and cold-adapted animals: proteins, peptides, and nonpeptide substances. We
also discuss the employment of molecular, biochemical, and physiological mechanisms of natural hypobiosis in ecology, cryomedicine,
and the cryopreservation of genetic material from rare and endangered species. We suppose that our approaches can be extensively
used (i) in medicine, when there is a need to slow down or suspend life processes for a short time; (ii) for the adaptation
of humans to the cold; and (iii) in long-term space flights. 相似文献
33.
34.
Popova IIu Vinogradova OS Kokoz IuM Ziganshin RKh Ivanov VT 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》2002,52(2):218-227
Our previous work demonstrated paradoxically increased excitability of the medial septal (MS) neurons during hibernation of ground squirrels in comparison to waking animals. Recently this was supported by demonstration of higher efficacy of the neuropeptides identified in the brain of hibernators in septal slices of hibernating animals. To decide whether this increased excitability is determined by endogenous properties of the pacemaker septal neurons, or it depends on the influences of thermoregulatory-circadian mechanisms of preoptico-hypothalamic area, testing of the neuropeptides (TSKYR, TSKY, DY) and neurotransmitters participating in control of hibernation (serotonin and noradrenaline) was repeated on septal slices taken from the brain of hibernating animals two weeks after operation disconnecting it from the hypothalamus. Effects of neuropeptides in the deafferented hibernating animals neither quantitatively (low reactivity level), nor qualitatively (distribution of inhibitory and excitatory responses) differed from the data obtained in waking animals. Decrease of reactivity occurred at the expense of the neurons with regular pacemaker-like spontaneous activity. Thus, increased reactivity of the MS neurons to neuropeptides in hibernating animals depends mainly on influence of the hypothalamic centres controlling hibernation behavior upon pacemaker neurons of the MS. Contrary to the neuropeptides, serotonin and noradrenaline were highly effective in deafferented septum. They evoked stronger changes of background activity (shorter latencies and more rapid development of maximal shifts), presumably as a result of development of denervation hypersensitivity after deafferentation. 相似文献
35.
Jain RK; Piskorz CF; Huang BG; Locke RD; Han HL; Koenig A; Varki A; Matta KL 《Glycobiology》1998,8(7):707-717
The selectins interact in important normal and pathological situations with
certain sialylated, fucosylated glycoconjugate ligands containing sialyl
Lewisx(Neu5Acalpha2-3Galbeta1-4(Fucalpha1-3)GlcN Ac). Much effort has gone
into the synthesis of sialylated and sulfated Lewisxanalogs as competitive
ligands for the selectins. Since the natural selectin ligands GlyCAM-1 and
PSGL-1 carry sialyl Lewisxas part of a branched Core 2 O-linked structure,
we recently synthesized Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-6(SE-3Galbeta1++
+-3)GalNAc1alphaOMe and found it to be a moderately superior ligand for L
and P-selectin (Koenig et al. , Glycobiology 7, 79-93, 1997). Other studies
have shown that sulfate esters can replace sialic acid in some selectin
ligands (Yeun et al. , Biochemistry, 31, 9126-9131, 1992; Imai et al. ,
Nature, 361, 555, 1993). Based upon these observations, we hypothesized
that Neu5Acalpha2-3Galbeta1-3GalNAc might have the capability of
interacting with L- and P-selectin. To examine this hypothesis, we
synthesized Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-6(Neu5Acalpha2++
+-3Galbeta1-3)- GalNAc alpha1-OB, which was found to be 2- to 3-fold better
than sialyl Lexfor P and L selectin, respectively. We also report the
synthesis of an unusual structure GalNAcbeta1-4(Fucalpha1-
3)GlcNAcbeta1-OMe (GalNAc- Lewisx-O-methyl glycoside), which also proved to
be a better inhibitor of L- and P-selectin than sialyl Lewisx-OMe.
Combining this with our knowledge of Core 2 branched structures, we have
synthesized a molecule that is 5- to 6-fold better at inhibiting L- and
P-selectin than sialyl Lewisx-OMe, By contrast to unbranched structures,
substitution of a sulfate ester group for a sialic acid residue in such a
molecule resulted in a considerable loss of inhibition ability. Thus, the
combination of a sialic acid residue on the primary (beta1-3) arm, and a
modified Lexunit on the branched (beta1-6) arm on an O-linked Core 2
structure generated a monovalent synthetic oliogosaccharide inhibitor
superior to SLexfor both L- and P-selectin.
相似文献
36.
Zenchenko KI Kokoz IuM Ivanov VT Ziganshin RKh Vinogradova OS 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》2000,50(2):231-243
Neuronal activity of the medial septal area (MS-DB) was recorded extracellularly in brain slices from two groups of Yakutian ground squirrels Citellus undulatus--hibernating (winter period) and actively waking (summer period). Effects of three neuropeptides identified in the brain of hibernators (TSKYR, TSKY, and DY) and of two monoamines (serotonin and noradrenaline) on spontaneous activity were analyzed. All neuropeptides reversibly changed the levels of the background activity, but in the hibernating ground squirrels (HGS) the level of reactivity (47-56%) was significantly higher than in the waking ground squirrels (WGS, 25-30%). Serotonin also showed some tendency to higher efficacy in the HGS. Only noradrenaline was equally effective and had absolutely dominating excitatory effect in both states, although the level of excitation in the HGS was higher. All other substances evoked excitatory and inhibitory effects in various proportions. Their distribution was state-dependent, the rate of development, intensity and duration of the effects were greater in the HGS. The experiments confirmed the data on higher excitability and reactivity of the septal neurons in the state of hibernation. It is suggested that the tested neuropeptides may participate in the control of hibernation. 相似文献
37.
TM?Matthews RK?Duncan M?Zidanic TH?Michael PA?FuchsEmail author 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2005,191(6):491-503
In the inner ear of birds, as in mammals, reptiles and amphibians, acetylcholine released from efferent neurons inhibits hair cells via activation of an apamin-sensitive, calcium-dependent potassium current. The particular potassium channel involved in avian hair cell inhibition is unknown. In this study, we cloned a small-conductance, calcium-sensitive potassium channel (gSK2) from a chicken cochlear library. Using RT-PCR, we demonstrated the presence of gSK2 mRNA in cochlear hair cells. Electrophysiological studies on transfected HEK293 cells showed that gSK2 channels have a conductance of approximately 16 pS and a half-maximal calcium activation concentration of 0.74±0.17 M. The expressed channels were blocked by apamin (IC50=73.3±5.0 pM) and d-tubocurarine (IC50=7.6±1.0 M), but were insensitive to charybdotoxin. These characteristics are consistent with those reported for acetylcholine-induced potassium currents of isolated chicken hair cells, suggesting that gSK2 is involved in efferent inhibition of chicken inner ear. These findings imply that the molecular mechanisms of inhibition are conserved in hair cells of all vertebrates. 相似文献
38.
Malysheva AN Storey KB Ziganshin RK Lopina OD Rubtsov AM 《Biochemistry. Biokhimii?a》2001,66(8):918-925
The total Ca-ATPase activity in the sarcoplasmic reticulum (SR) membrane fraction isolated from skeletal muscles of winter hibernating ground squirrel Spermophilus undulatus is 2.2-fold lower than in preparations obtained from summer active animals. This is connected in part with 10% decrease of the content of Ca-ATPase protein in SR membranes. However, the enzyme specific activity calculated with correction for its content in SR preparations is still 2-fold lower in hibernating animals. Analysis of the protein composition of SR membranes has shown that in addition to the decrease in Ca-ATPase content in hibernating animals, the amount of SR Ca-release channel (ryanodine receptor) is decreased 2-fold, content of Ca-binding proteins calsequestrin, sarcalumenin, and histidine-rich Ca-binding protein is decreased 3-4-fold, and the amount of proteins with molecular masses 55, 30, and 22 kD is significantly increased. Using the cross-linking agent cupric–phenanthroline, it was shown that in SR membranes of hibernating ground squirrels Ca-ATPase is present in a more aggregated state. The affinity of SR membranes to the hydrophilic fluorescent probe ANS is higher and the degree of excimerization of the hydrophobic probe pyrene is lower (especially for annular lipids) in preparations from hibernating than from summer active animals. The latter indicates an increase in the microviscosity of the lipid environment of Ca-ATPase during hibernation. We suggest that protein aggregation as well as the changes in protein composition and/or in properties of lipid bilayer SR membranes can result in the decrease of enzyme activity during hibernation. 相似文献
39.
The clinico-immunological study of 80 patients with chronic prostatitis of different etiology was carried out. As controls, 20 healthy adult males were used. Mucous membranes of the reproductive tract were found to have different mechanisms of antimicrobial protection whose disturbances led to the inflammatory process. The clinico-immunological analysis carried out in the course of this study made it possible to state that, in contrast to healthy adults, pronounced changes in the characteristics of the local immunity status of the reproductive system occur in chronic prostatitis patients. 相似文献
40.