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121.
Suppressing oxygen release from lithium ion battery cathodes during heating is a critical issue for the improvement of the battery safety characteristics because oxygen can exothermically react with the flammable electrolyte and cause thermal runaway. Previous studies have shown that oxygen release can be reduced by the migration of transition metal cations from octahedral sites to tetrahedral sites during heating. Such site‐preferred migration is determined by the electronic structure of cations. Taking advantage of the unique electronic structure of the environmental friendly Fe, this is selected as substitution element in a high energy density material LiNi0.5Mn1.5O4 to improve the thermal stability. The optimized LiNi0.33Mn1.33Fe0.33O4 material shows significantly improved thermal stability compared with the unsubstituted one, demonstrated by no observed oxygen release at temperatures as high as 500°C. Due to the electrochemical contribution of Fe, the high energy density feature of LiNi0.5Mn1.5O4 is well preserved.  相似文献   
122.
A new, rod-shaped, Gram-negative, non-sporing sulfate reducer (strain Ani1) was enriched and isolated from marine sediment with aniline as sole electron donor and carbon source. The strain degraded aniline completely to CO2 and NH3 with stoichiometric reduction of sulfate to sulfide. Strain Ani1 also degraded aminobenzoates and further aromatic and aliphatic compounds. The strain grew in sulfide-reduced mineral medium supplemented only with vitamin B12 and thiamine. Cells contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P582, but no desulfoviridin. Strain Ani1 is described as a new species of the genus Desulfobacterium D. anilini. Marine enrichments with the three dihydroxybenzene isomers led to three different strains of sulfate-reducing bacteria; each of them could grow only with the isomer used for enrichment. Two strains isolated with catechol (strain Cat2) or resorcinol (strain Re10) were studied in detail. Both strains oxidized their substrates completely to CO2, and contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P 582. Desulfoviridin was not present. Whereas the rod-shaped catechol oxidizer (strain Cat2) was able to grow on 18 aromatic compounds and several aliphatic substrates, the coccoid resorcinol-degrading bacterium (strain Re10) utilized only resorcinol, 2,4-dihydroxybenzoate and 1,3-cyclohexanedion. These strains could not be affiliated with existing species of sulfate-reducing bacteria. A further coccoid sulfate-reducing bacterium (strain Hy5) was isolated with hydroquinone and identified as a subspecies of Desulfococcus multivorans. Most-probable-number enumerations with catechol, phenol, and resorcinol showed relatively large numbers (10(4)-10(6) per ml) of aryl compound-degrading sulfate reducers in marine sediment samples.  相似文献   
123.
Avery B  Bak A  Schmidt M 《Theriogenology》1989,32(1):139-147
The purpose of this study was to determine whether a correlation between embryonic cleavage rates and sex ratios in dairy cattle could be substantiated. Embryos were collected at Day 7 after estrus following superovulation and artificial insemination. Embryos from flushings where at least two different developmental stages within the same flushing could be identified were examined. A total of 476 such embryos was transferred to recipients and 110 calves were born. The sex effect was only demonstrable in flushings yielding embryos of at least three different developmental stages. The sex ratios from this group were 32%, 58% and 62% in the slow, intermediate and fast developing groups of embryos, respectively. The deviations were not significant (P = 0.084). Only 23% of the flushings provided embryos that fell into this cathegory, which limits the use of differential cleavage rates as a sexing method, unless additional embryo culture is introduced to the technique.  相似文献   
124.
Effects of insulin on plasma concentration and renal excretion of sodium and potassium were compared in conscious dogs 1) maintained in water and electrolytes balance (Series 1, 10 dogs), 2) depleted of electrolytes by repeated i.v. loading with 20% mannitol (Series 2, 10 dogs), and 3) aldosterone treated (0.8 micrograms.kg-1.h-1 i.v., Series 3, 10 dogs). In each Series intravenous infusion of insulin at a rate of 0.05 U.kg-1.h-1 elicited transient increase in plasma sodium concentration and prolonged hypokalemia. Repeated loading with mannitol in Series 2 elicited significant elevation of plasma sodium, ADH and aldosterone concentrations, as well as decrease in extracellular fluid volume. Infusion of insulin in this Series elicited smaller decrease in plasma potassium concentration and longer lasting hypernatremia than in dogs in water-electrolytes balance. Aldosterone infusion in Series 3 did not change hypokalemic effect of insulin but attenuated hypernatremia. Infusion of insulin in Series 1 elicited increase of sodium excretion and decrease in potassium excretion. These effects were absent in Series 2 and 3. The results indicate that depletion of electrolytes and blood aldosterone elevation modify the effects of insulin on plasma concentration and renal excretion of sodium and potassium.  相似文献   
125.
A dramatic difference is observed in the intracellular distribution of the high mobility group (HMG) proteins when chicken embryo fibroblasts are fractionated into nucleus and cytoplasm by either mass enucleation of cytochalasin-B-treated cells or by differential centrifugation of mechanically disrupted cells. Nuclei (karyoplasts) obtained by cytochalasin B treatment of cells contain more than 90 percent of the HMG 1, while enucleated cytoplasts contain the remainder. A similar distribution between karyoplasts and cytoplasts is observed for the H1 histones and the nucleosomal core histones as anticipated. The presence of these proteins, in low amounts, in the cytoplast preparation can be accounted for by the small percentage of unenucleated cells present. In contrast, the nuclei isolated from mechanically disrupted cells contain only 30-40 percent of the total HMGs 1 and 2, the remainder being recovered in the cytosol fraction. No histone is observed in the cytosol fraction. Unike the higher molecular weight HMGs, most of the HMGs 14 and 17 sediment with the nuclei after cell lysis by mechanical disruption. The distribution of HMGs is unaffected by incubating cells with cytochalasin B and mechanically fractionating rather than enucleating them. Therefore, the dramatic difference in HMG 1 distribution observed using the two fractionation techniques cannot be explained by a cytochalasin-B-induced redistribution. On reextraction and sedimentation of isolated nuclei obtained by mechanical cell disruption, only 8 percent of the HMG 1 is released to the supernate. Thus, the majority of the HMG 1 originally isolated with these nuclei, representing 35 percent of the total HMG 1, is stably bound, as is all the HMGs 14 and 17. The remaining 65 percent of the HMGs 1 and 2 is unstably bound and leaks to the cytosol fraction under the conditions of mechanical disruption. It is suggested that the unstably bound HMGs form a protein pool capable of equilibrating between cytoplasm and stably bound HMGs.  相似文献   
126.
Zusammenfassung Die normale Substruktur der Pyramidenzellen aus den Feldern CA 2, CA 3 und CA 4 vom Ammonshorn des Kaninchens wurde elektronenmikroskopisch untersucht.Nach unseren Beobachtungen zeichnen sich die Perikarya aller Pyramidenzellen der Ammonshornfelder durch eine charakteristische Anordnung und Lokalisation der Zellorganellen aus. Der stets zentral gelegene Kern wird von einem unvollständigen Ergastoplasmasaum umgeben. Im Bereich des apikalen Dendritenabgangs vergrößert sich dieser Saum zur sog. Kernkappe. Daran schließt sich eine Cytoplasmazone an, die außer einigen Ergastoplasmaanteilen in der Hauptsache die Golgi-Komplexe, zum größten Teil aber auch die Mitochondrien und Zellgranula enthält. An diese Zone des Perikaryons grenzt der Randschollensaum des Ergastoplasmas, das hier die massivste Aggregation von geordnetem Ergastoplasma in der Pyramidenzelle bildet. Sowohl die Zone des Randschollensaums des Ergastoplasmas als auch die Zone der Golgi-Komplexe setzen sich in die Dendriten fort.Außer der Feinstruktur der einzelnen Zellorganellen (Zellkern, Ergastoplasma, Golgi-Komplexe, Mitochondrien) werden die Zellgranula morphologisch analysiert. Mit Hilfe cytochemischer Reaktionen auf saure Phosphatase konnte festgestellt werden, daß der größte Teil dieser Granula zu den Lysosomen gehört.  相似文献   
127.
THE FATE OF MITOCHONDRIA DURING AGING IN TETRAHYMENA PYRIFORMIS   总被引:10,自引:6,他引:4       下载免费PDF全文
During the growth cycle of Tetrahymena pyriformis the mitochondria undergo changes in position, number, and structure. Ciliates in the logarithmic growth phase possess elongated mitochondria which are aligned along the plasma membrane and are closely associated with the kinetosomes and kinetodesmata. Mitochondria appear to divide across the long axis at this time, resulting in two or more products. Throughout this phase of growth mitochondrial divisions keep pace with cytokinesis so that the population of mitochondria remains at essentially the minimal level. As the ciliates enter the stationary growth phase the mitochondria increase in number, become oval to spherical in shape, and some migrate into the cytoplasm. Intramitochondrial masses of various configurations appear at this time. Some of the mitochondria lying in the cytoplasm become incorporated into vacuoles. Within these vacuoles either a single mitochondrion appears or several mitochondria may be seen along with other cytoplasmic structures. Later in the stationary growth phase the contained mitochondria are dense and the tubules are more compact than normal. Various stages in disorganization of the mitochondria are observed in a single large vacuole. Cytochemical tests reveal the presence of acid phosphatase, suggesting that hydrolysis of the vacuolar contents occurs. Lipid droplets increase in number during the middle and late stationary phase of growth. These events are interpreted as being associated with the normal process of aging in T. pyriformis.  相似文献   
128.
The titration of sonicated vesicles of egg phosphatidylcholine with ferricyanide in the presence of Ca2+ results in the formation of aggregates. The turbidity increase caused by these aggregates cannot be reversed by EDTA treatment. In addition, no rearrangement of the bilayer structure has been found in this process, either measuring leakage of vesicle content or exchange of lipids among the bilayers themselves. The aggregation is dependent on the Ca2+ content of the vesicles, the outer Ca2+ and Fe(CN)3-(6) concentration and the order of addition of Ca2+ and ferricyanide. The results can be explained by a specific adsorption of Fe(CN)3-(6) to bilayers of sonicated vesicles, in contrast to other multivalent anions. In contrast to the stability found with sonicated vesicles, the aggregation causes a leakage of the internal solution when multilamellar liposomes are titrated with Fe(CN)3-(6).  相似文献   
129.
Abstract The effect of temperature on CH4 production, turnover of dissolved H2, and enrichment of H2-utilizing anaerobic bacteria was studied in anoxic paddy soil and sediment of Lake Constance. When anoxic paddy soil was incubated under an atmosphere of H2/CO2, rates of CH4 production increased 25°C, but decreased at temperatures lower than 20°C. Chloroform completely inhibited methano-genesis in anoxic paddy soil and lake sediment, but did not or only partially inhibit the turnover of dissolved H2, especially at low incubation temperatures. Cultures with H2 as energy source resulted in the enrichment of chemolithotrophic homoacetogenic bacteria whenever incubation temperatures were lower than 20°C. Hydrogenotrophic methanogens could only be enriched at 30°C from anoxic paddy soil. A homoacetogen  相似文献   
130.
A simple mathematical model to predict initial breakthrough profiles from preparative chromatographic separations of biological macromolecules has been developed. A lumped parameter approach was applied, employing Langmuirian adsorption kinetics to describe the rate of mass transfer (MT) from the bulk liquid in the column to the bound state. Equilibrium and kinetic adsorption data were determined for six different packed bed chromatographic adsorbents: two derivatised with rProtein A; and four functionalised with synthetic low molecular weight ligands. All adsorption isotherms were well described by the Langmuir model, whereas the data fitting to kinetic batch experiments showed that the model was inadequate after the first approximately 25 min of adsorption for four of the six adsorbents. The model underestimated the dynamic Ig breakthough on packed beds of rProtein A Sepharose FF, MabSelect, MBI HyperCel, and MabSorbent A1P, applying a feedstock of 20-100% (v/v) clarified rabbit antiserum. However, when employing a maximum adsorption capacity 25% greater than that determined in batch binding studies, excellent agreement was obtained at all antiserum strengths for most adsorbents. Useful insights into scale-up and process design can be obtained by applying the model, without determining tentative parameters specific for each adsorbent and target protein concentration. However, the model parameters are solvent dependent so a prerequisite for its true applicability is that binding is both Langmuirian and essentially independent of the ionic strength of the feedstock applied.  相似文献   
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