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71.
Death inducer-obliterator 1 triggers apoptosis after nuclear translocation and caspase upregulation 下载免费PDF全文
García-Domingo D Ramírez D González de Buitrago G Martínez-A C 《Molecular and cellular biology》2003,23(9):3216-3225
Death inducer-obliterator 1 (DIO-1) is a gene that is upregulated early in apoptosis. Here we report that in healthy cells, the DIO-1 gene product was located in the cytoplasm, where it formed oligomers. After interleukin-3 starvation or c-Myc-induced apoptosis in serum-free conditions, DIO-1 translocated to the nucleus, where it upregulated caspase levels and activity. A nuclear localization signal deletion mutant (DIO-1deltaNLS) was unable to translocate to the nuclear compartment in the absence of interleukin-3 and failed to upregulate procaspase levels or trigger cell death. In addition, cells stably expressing DIO-1deltaNLS were protected from apoptosis induced by interleukin-3 withdrawal. These results indicate that DIO-1 has a relevant role in regulating the early stages of cell death. 相似文献
72.
Muscle fiber response to a train of variable-frequency pulses includes the potentiation and catch-like effect. For better
understanding of these phenomena, we built an activation model with emphasis on the calcium liberation from and re-sequestration
into the sarcoplasmic reticulum, including calcium-induced calcium release. The model had two stable equilibrium points in
the calcium concentration. Changes from the low to the high equilibrium point could be produced by high-frequency trains of
pulses and would account for the potentiation. The model also showed a catch-like effect, as a long-lasting increment of muscle
force after the application of a single extra pulse. The increase in force appeared in resting muscle, disappeared when the
muscle was potentiated, and reappeared briefly if the stimulation was continued for long periods.
Received: 31 January 2000 / Accepted in revised form: 2 August 2000 相似文献
73.
Rubidium uptake in potassium-starved cells followed biphasic kinetics in the micromolar and millimolar range and was independent
of the temperature. In contrast, Rb+ uptake in normal-K+ cells followed a monophasic kinetics in the millimolar range and increased at temperatures higher than 30°C. Differences
in the K
m
values and in the Arrhenius plots of Rb+ uptake suggest different uptake systems in K+-starved and in normal-K+ cells. In addition, the substantial inhibition of Rb+ uptake caused by carbonyl cyanide-m-chlorophenyl hydrazone indicates that these systems are strongly dependent on membrane voltage. Lithium (sodium) tolerance,
influx, and efflux were separately studied. F. oxysporum was shown to be very tolerant to sodium, while lithium caused a specific toxic effect. Li+ uptake in K+-starved cells exhibits a monophasic kinetics with low affinity. Li+ efflux was not affected by external pH or addition of potassium to the medium, suggesting that a Na+/cation antiporter is not involved in this process.
Received: 14 March 2000 / Accepted: 5 June 2000 相似文献
74.
Jault JM Fieulaine S Nessler S Gonzalo P Di Pietro A Deutscher J Galinier A 《The Journal of biological chemistry》2000,275(3):1773-1780
Carbon catabolite repression allows bacteria to rapidly alter the expression of catabolic genes in response to the availability of metabolizable carbon sources. In Bacillus subtilis, this phenomenon is controlled by the HPr kinase (HprK) that catalyzes ATP-dependent phosphorylation of either HPr (histidine containing protein) or Crh (catabolite repression HPr) on residue Ser-46. We report here that B. subtilis HprK forms homo-oligomers constituted most likely of eight subunits. Related to this complex structure, the enzyme displays strong positive cooperativity for the binding of its allosteric activator, fructose 1,6-bisphosphate, as evidenced by either kinetics of its phosphorylation activity or the intrinsic fluorescence properties of its unique tryptophan residue, Trp-235. It is further shown that activation of HPr phosphorylation by fructose 1,6-bisphosphate essentially occurs at low ATP and enzyme concentrations. A positive cooperativity was also detected for the binding of natural nucleotides or their 2'(3')-N-methylanthraniloyl derivatives, in either phosphorylation or fluorescence experiments. Most interestingly, quenching of the HprK tryptophan fluorescence by using either iodide or acrylamide revealed a heterogeneity of tryptophan residues within the population of oligomers, suggesting that the enzyme exists in two different conformations. This result suggests a concerted-symmetry model for the catalytic mechanism of positive cooperativity displayed by HprK. 相似文献
75.
Silvestre MD Lagarda MJ Farré R Martínez-Costa C Brines J Molina A Clemente G 《Biological trace element research》2000,76(3):217-227
The aim of this study was to establish the possible effects of the sampling protocol (between-breast, within-feed, and diurnal
differences) and the mother’s personal factors (age, parity, iron supple-mentation, smoking habits, and lactation period)
on the copper, iron, and zinc contents in human milk.
One hundred thirty-six human milk samples identified by their origin and sampling conditions were analyzed. The samples were
obtained from the 2nd to 15th d postpartum from 62 women. The data on the individuals required for the study were available.
Mineral determinations were analyzed by flame atomic absorption spectrometry following a standarized protocol.
The results showed that iron contents were higher in hind-milk samples and at the nighttime feeding and depended on the breast
from which the sample was taken. The copper and zinc concentrations showed no significant variations. There was no significant
relationship among the mothers’ age, parity, smoking habits, iron supplementation, and copper content. Milk from older women
had lower zinc contents than that of younger women. Increased amounts of iron were found in multiparous women. Between colostrum
and transitional milk, a sharp decrease in zinc content was observed, whereas copper and iron contents remained constant.
All of these results make it clear that standardized sampling protocols are needed in order to obtain comparable values. 相似文献
76.
77.
Aims The fauna of mountains and their surrounding regions are likely to be influenced principally by two biological processes: horizontal colonization along similar altitudinal levels by elements originating from lineages inhabiting higher latitudes; and vertical colonization by lineages from the same latitude, but at lower altitudes. We examine whether the expected patterns derived from the latter process can be observed in mountain dung beetle assemblages. Specifically, we study the variation in species composition and richness with altitude in five regions spanning elevation gradients, analysing whether the altitudinal rates of change in the number of species and genera differ, and whether beta‐diversity scores for adjacent sites in each altitudinal gradient are different for species and genera. Location Eastern Cordillera of the Colombian Andes. Methods Field work was carried out in 1997–99 at 27 sites in five regions with elevation gradients, with 10–32 pitfall traps placed in each site. For each altitudinal level the numbers of species and genera were analysed with respect to altitude, and the slope of the linear regression between these variables was calculated. The slope of the curve of the altitude against the cumulative number of species and genera was also calculated for each altitudinal gradient to describe the compositional change between adjacent sites (beta diversity). Species and generic slopes were compared using analysis of covariance. The turnover of species along each altitudinal gradient was measured using presence/absence data and Cody's beta‐diversity index between adjacent pairs of sites. A cluster analysis was used to detect faunistically homogeneous groups of localities. Results Species richness always decreased with altitude, although the slopes did not differ significantly from zero. The number of genera also decreased with increasing altitude, but generally at a significantly slower rate than for species. Variation in the species beta‐diversity scores between altitudinal levels did not follow a homogeneous pattern in the different regions. Two main altitudinal groups of sites with a boundary c. 1500–1750 m a.s.l. can be detected with respect to faunistic similarity. Low‐ and mid‐altitude sites are inhabited by all of the genera (19) and 80% of all species collected. Eight genera and 61 species (c. 60% of the total) are unable to inhabit high‐altitude sites, and only 20 species appear to be exclusive to these high‐altitude environments (> 2000 m a.s.l.). Main conclusions The dominant processes explaining dung beetle composition in the high north‐eastern Andean mountains are probably those of vertical colonization. The limited role of horizontal colonization processes, or colonization from northern or southern lineages, could be a consequence of the isolation and recent geological origin of these mountains. 相似文献
78.
Miria Gomes Pereira Gonzalo Visbal Leonardo T. Salgado Juliana Cunha Vidal Joseane L. P. Godinho Nuccia N. T. De Cicco Geórgia C. Atella Wanderley de Souza Narcisa Cunha-e-Silva 《PloS one》2015,10(6)
Trypanosoma cruzi epimastigotes store high amounts of cholesterol and cholesteryl esters in reservosomes. These unique organelles are responsible for cellular digestion by providing substrates for homeostasis and parasite differentiation. Here we demonstrate that under nutritional lipid stress, epimastigotes preferentially mobilized reservosome lipid stocks, instead of lipid bodies, leading to the consumption of parasite cholesterol reservoirs and production of ergosterol. Starved epimastigotes acquired more LDL-NBD-cholesterol by endocytosis and distributed the exogenous cholesterol to their membranes faster than control parasites. Moreover, the parasites were able to manage internal cholesterol levels, alternating between consumption and accumulation. With normal lipid availability, parasites esterified cholesterol exhibiting an ACAT-like activity that was sensitive to Avasimibe in a dose-dependent manner. This result also implies that exogenous cholesterol has a role in lipid reservoirs in epimastigotes. 相似文献
79.
Sara Garcia‐Serrano Carolina Gutiérrez‐Repiso Montserrat Gonzalo Juan Garcia‐Arnes Sergio Valdes Federico Soriguer Vidal Perez‐Valero Miguel A. Alaminos‐Castillo Juan Francisco Cobos‐Bravo Francisco J. Moreno‐Ruiz Alberto Rodriguez‐Cañete Francisca Rodríguez‐Pacheco Eva Garcia‐Escobar Eduardo García‐Fuentes 《Obesity (Silver Spring, Md.)》2015,23(8):1607-1615
80.