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21.
Giménez-Abián JF Sumara I Hirota T Hauf S Gerlich D de la Torre C Ellenberg J Peters JM 《Current biology : CB》2004,14(13):1187-1193
Sister chromatid separation in anaphase depends on the removal of cohesin complexes from chromosomes. In vertebrates, the bulk of cohesin is already removed from chromosome arms during prophase and prometaphase, whereas cohesin remains at centromeres until metaphase, when cohesin is cleaved by the protease separase. In unperturbed mitoses, arm cohesion nevertheless persists throughout metaphase and is principally sufficient to maintain sister chromatid cohesion. How arm cohesion is maintained until metaphase is unknown. Here we show that small amounts of cohesin can be detected in the interchromatid region of metaphase chromosome arms. If prometaphase is prolonged by treatment of cells with microtubule poisons, these cohesin complexes dissociate from chromosome arms, and arm cohesion is dissolved. If cohesin dissociation in prometaphase-arrested cells is prevented by depletion of Plk1 or inhibition of Aurora B, arm cohesion is maintained. These observations imply that, in unperturbed mitoses, small amounts of cohesin maintain arm cohesion until metaphase. When cells lacking Plk1 and Aurora B activity enter anaphase, chromatids lose cohesin. This loss is prevented by proteasome inhibitors, implying that it depends on separase activation. Separase may therefore be able to cleave cohesin at centromeres and on chromosome arms. 相似文献
22.
Giménez-Bonafé P Soler FM Buesa C Sautière PE Ausió J Kouach M Kasinsky HE Chiva M 《Molecular reproduction and development》2004,68(2):232-239
In this article we study the proteins responsible for chromatin condensation during spermiogenesis in the cephalopod Octopus vulgaris. The DNA of ripe sperm nuclei in this species is condensed by a set of five different proteins. Four of these proteins are protamines. The main protamine (Po2), a protein of 44 amino acid residues, is extraordinarily simple (composed of only three different amino acid types: arginine (R), serine (S), and glycine (G). It is a basic molecule consisting of 79.5 mol% arginine residues. The rest of the protamines (Po3, Po4, Po5) are smaller molecules (33, 28, and 30 amino acid residues, respectively) that are homologous among themselves and probably with the main Po2 protamine. The ripe sperm nucleus of O. vulgaris also contains a small quantity of a molecule (Po1) that is similar to Po2 protamine. This protein could represent a Po2 protamine-precursor in a very advanced step of its processing. We discuss the characteristics of these proteins, as well as the relation between the complexity of chromatin condensation and the transitions of nuclear proteins during spermiogenesis in O. vulgaris. 相似文献
23.
Lin HJ Johansson AS Stenberg G Materi AM Park JM Dai A Zhou H Gim JS Kau IH Hardy SI Parker MW Mannervik B 《Biochimica et biophysica acta》2003,1649(1):16-23
Glutathione transferases (GSTs) are a family of enzymes that detoxify electrophilic compounds, such as carcinogens or drugs, by conjugating them to glutathione. The enzymes have contributed to the understanding of protein structure, due to large differences in amino acid sequence within the family, yet similar architecture and folding. Our objective was to conduct a systematic survey of GSTP1 polymorphisms and their function. Nearly all variants detected were known polymorphisms: IVS4+13C>A; Ile105Val; Ala114Val; and g.2596T>C (Ser185Ser). However, we also found a novel Phe151Leu substitution in an African-American subject (1 out of 111). Kinetic parameters for the conjugation reaction with 1-chloro-2,4-dinitrobenzene (CDNB) were determined for the novel variant enzyme purified via heterologous expression in Escherichia coli. Five substrates were used for measurement of specific activities, including isothiocyanate compounds that occur in cruciferous vegetables (benzylisothiocyanate, phenethylisothiocyanate, and sulforaphane). Such isothiocyanate substrates are potential cancer chemopreventive agents that are conjugated by GSTs. No major change in kinetic parameters was observed. However, the half-life at 50 degrees C of the Leu 151 enzyme was reduced to 12 min, as compared to 28 min for the Phe 151 enzyme. Residue 151 is located at the N-terminus of helix alpha6 in GST motif II, surrounded by hydrophobic residues, and near the conserved "hydrophobic staple" and N-capping box motifs. These local structural elements aid in formation of helix alpha6 and promote proper folding and protein stability. Analysis of the three-dimensional structure showed that substitution of Phe 151 with Leu produces a hydrophobic cavity in the GSTP1 core, thereby destabilizing its structure. Phe151Leu represents one of the first-described allelic variations in a protein folding motif. 相似文献
24.
25.
Vázquez-López C de Armas-Serra C Pérez-Serrano J Giménez-Pardo C Rodríguez-Caabeiro F 《Journal of helminthology》2000,74(2):183-187
A 24-kDa collagenase was localized in the Gymnorhynchus gigas plerocercoid immunohistochemically by peroxidase complex staining using polyclonal antibodies from NMRI mouse sera immunized with purified enzyme. Immunoreactivity was determined at different parts of the body (scolex, vesicle and caudal region) and mainly localized in microtriches and parenchymal tissues of the scolex and vesicle. These results, along with the absence of the enzyme in the plerocercoid excretion-secretion products, suggest that the 24-kDa collagenase is produced by parenchymal cells in the anterior region and transported to the outer regions of the worm It is possible that the enzyme plays an important role in degrading parasite tissues during the moulting process. 相似文献
26.
González-Fandos E Giménez M Olarte C Sanz S Simón A 《Journal of applied microbiology》2000,89(4):624-632
Mushrooms were packed in two polymeric films (perforated and non-perforated PVC) and stored at 17 degrees C and 25 degrees C. The carbon dioxide and oxygen content inside the packages, aerobic mesophiles, Pseudomonas spp., faecal coliforms, Escherichia coli, anaerobic spores and major sensory factors (colour, texture, development stage and presence of moulds) were determined. The non-perforated packages had the highest contents of CO2 (6-7%), the lowest contents of O2 (0.013-0.17%) and the most desirable quality parameters (texture, development stage and absence of moulds). Pseudomonas spp. counts were around 1 logarithmic unit lower in mushrooms packaged in non-perforated film as the O2 concentrations were lower than in perforated film. The mushrooms themselves were inoculated with an enterotoxin A-producing strain of Staphylococcus aureus, packaged in overwrapped trays and stored at 17 and 25 degrees C. Staphylococcus aureus did not grow in the samples stored at 17 degrees C. Only slight growth was observed in mushrooms packaged with non-perforated film after 1 day at 25 degrees C. No enterotoxin was detected in any package. Faecal coliform counts were <2 log cfu g(-1). Escherichia coli was not isolated in any of the samples. At 25 degrees C, counts of anaerobic spores of around 2 log cfu g(-1) were detected in those mushrooms packaged in non-perforated film. 相似文献
27.
Giménez-Abián JF Clarke DJ Devlin J Giménez-Abián MI De la Torre C Johnson RT Mullinger AM Downes CS 《Chromosoma》2000,109(4):235-244
When DNA topoisomerase II (topo II) activity is inhibited with a non-DNA-damaging topo II inhibitor (ICRF-193), mammalian
cells become checkpoint arrested in G2-phase. In this study, we analyzed chromosome structure in cells that bypassed this
checkpoint. We observed a novel type of chromosome aberration, which we call Ω-figures. These are entangled chromosome regions
that indicate the persistence of catenations between nonhomologous sequences. The number of Ω- figures per cell increased
sharply as cells evaded the transient block imposed by the topo II-dependent checkpoint, and the presence of caffeine (a checkpoint-evading
agent) potentiated this increase. Thus, the removal of nonreplicative catenations, a process that promotes chromosome individualization
in G2, may be monitored by the topo II-dependent checkpoint in mammals.
Received: 19 July 1999; in revised form: 20 October 1999 / Accepted: 7 January 2000 相似文献
28.
Dr. C. Broberger D. Blacker L. Giménez-Llort M. Herrera-Marschitz S. -O. Ögren T. Hükfelt 《Amino acids》1998,14(1-3):25-31
Summary Motor behaviour relies on complex neurochemical interactions in the basal ganglia, in particular the striatum. Antagonistic influences in this region are exerted by afferent projections from, on the one hand, the ventral mesencephalon, utilizing dopamine as a transmitter, and, on the other hand, from the cerebral cortex, signalling by the excitatory amino acid glutamate. The activity in both these neuronal populations appears to be regulated by the neuropeptide cholecystokinin. This article concentrates on interactions between cholecystokinin and glutamate, summarizing some recent morphological, biochemical and behavioural findings. It is suggested that cholecystokinin, acting via the cholecystokininB receptor, potentiates the glutamatergic excitatory input to the striatum. 相似文献
29.
Presence or absence of N-acetylneuraminic acid (Neu5Ac) can change a
sialylated glycoprotein's serum half-life and possibly its function. We
evaluated the linearity, sensitivity, reproducibility, and accuracy of a
HPAEC/PAD method to determine its suitability for routine simultaneous
analysis of Neu5Ac and N-glycolylneuraminic acid (Neu5Gc). An effective
internal standard for this analysis is 3-deoxy-d-glycero-d-
galacto-2-nonulosonic acid (KDN). We investigated the effect of the Au
working electrode recession and determined that linear range and
sensitivity were dependent on electrode recession. Using an electrode that
was 350 &mgr;m recessed from the electrode block, the minimum detection
limits of Neu5Ac, KDN, and Neu5Gc were 2, 5, and 2 pmol, respectively, and
were reduced to 1, 2, and 0.5 pmol using a new electrode. The response of
standards was linear from 10 to 500 pmol (r2>0.99) regardless of
electrode recession. When Neu5Ac, KDN, and Neu5Gc (200 pmol each) were
analyzed repetitively for 48 h, area RSDs were <3%. Reproducibility was
unaffected when injections of glycoprotein neuraminidase and acid
digestions were interspersed with standard injections. Area RSDs of Neu5Ac
and Neu5Gc improved when the internal standard was used. We determined the
precision and accuracy of this method for both a recessed and a new working
electrode by analyzing Neu5Ac and Neu5Gc contents of bovine fetuin and
bovine and human transferrins. Results were consistent with published
values and independent of the working electrode. The sensitivity,
reproducibility, and accuracy of this method make it suitable for direct
routine analysis of glycoprotein Neu5Ac and Neu5Gc contents.
相似文献
30.
Gilda J. Erosa-Rejón Alejandro Yam-Puc Manuel J. Chan-Bacab Alberto Giménez-Turbax Efraín Salamanca Luis M. Peña-Rodríguez Olov Sterner 《Phytochemistry letters》2010,3(1):9-12
Two new benzochromenes, (6,6-dimethyl-2-methoxy-6H-benzo[c]chromen-9-yl)methanol (1), and 2-methoxy-6,6-dimethyl-6H-benzo[c]chromen-9-carbaldehyde (2), together with several already known metabolites, were isolated from the root extract of Bourreria pulchra (Boraginaceae). The structures of 1 and 2 were established on the basis of their spectroscopic data. Both were assayed for in vitro antiprotozoan activity, and especially 1 was found to possess significant activity against Leishmania mexicana and Trypanosoma cruzi parasites (IC50 4.6 μg/mL and 7.5 μg/mL, respectively). 相似文献