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A Rapid Screening Test for Aflatoxin-synthesizing Aspergilli of the flavus-oryzae Group 总被引:1,自引:1,他引:0
P. de Vogel Renée van Rhee W. A. A. Blanche Koelensmid 《Journal of applied microbiology》1965,28(2):213-220
A rapid test for the recognition of aflatoxin-synthesizing strains of the Aspergillus flavus–oryzae group is described. For this purpose the strains are cultivated on Czapek–Dox agar enriched with an aqueous extract of groundnuts, and in which sodium nitrate is replaced by ammonium chloride. Toxin production is observed by the production of a bright blue fluorescence in the medium when placed under an ultraviolet lamp. 相似文献
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Summary A heterologous gene from bloodsucking leech for anticoagulant, hirudin, has been expressed in the methylotrophic yeast Hansenula polymorpha. The addition of 1%(v/v) soybean oil to the medium as a stabilizer enhanced the expression of the hirudin gene in H. polymorpha with MOX promoter. The production of hirudin in the medium with soybean oil was 320mg/L in a 5L fermenter. 相似文献
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Batch and continuous hydrolysis of olive oil in an organic-aqueous two-phase system using the live whole cell of Pseudomonas putida 3SK as a source of a lipase is investigated. The strain was not only fully viable and grown well, but also produced extracellular lipase simultaneously. The degree of hydrolysis, depending on olive oil concentration in the solvents, was maximal at 13.5% (w/v) and decreased with the increase of the substrate concentration. At the optimal condition, a degree of hydrolysis higher than 95% was achieved with 24 h at 30 degrees C when the reaction was carried out in a two-phase batch stirred reactor. For long-term operation a continuous stirred reactor was designed. When the reaction was carried out in a continuous stirred reactor, the degree was hydrolysis reached 86% at a dilution rate of 0.2 h(-1). Satisfactory performance of a two-phase bioreactor was obtained in a long-term continous operation, which lasted for at least 30 days by feeding organic solvent containing olive oil and aqueous media separately. (c) 1994 John Wiley & Sons, Inc. 相似文献
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SPA::EcoRI fusion protein was produced by Escherichia coli JM103 carrying the multicopy expression plasmid pMTC48, the multicopy repressor plasmid pRK248, and the multicopy protection plasmid pEcoR4 in a 60-L working volume airlift tower loop reactor on M9 minimal medium with glucose. Cell mass concentration, total cell count, number of colony-forming units, specific growth rate, yield coefficient, and metabolite (acetate, pyruvate, succinate, lactate, ethanol) concentrations were monitored during the growth phase and gene expression. Gene expression was induced by temperature shift or chemically by isopropyl-thiogalactosidase in the airlift tower loop reactor (ALTR) at constant cultivation time and in a small stirred tank reactor at different cultivation times. During induction, the cultivation medium was supplemented with concentrated Luria-Bertani (LB) medium. The intracellular enzyme activity was evaluated as a function of the time after the start of the induction. It was found that the reduction of the glucose concentration and increase of the dissolved oxygen concentration reduced the acetate produced and increased the intracellular enzyme activity. (c) 1993 John Wiley & Sons, Inc. 相似文献
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Kinetics of cell death and the production of dissolved organic carbon (DOC) were investigated in Anabaena flos-aquae (Lyngb.) Bréb grown on three different N sources (N2nitrate, and ammonium) in a phosphorus (P)-limited chemostat. The fraction of live cells in the total population increased as growth rate increased with decreasing P limitation. Cell death was less in nitrate and ammonium media than in N2. The specific death rate (γ), when calculated as the slope ofv?1x vs. D?1, where vxand D are live cell fraction (or cell viability) and dilution rate, respectively, was 0. 0082 day?1 in N2and 0.0042 day?1 in nitrate. The slope of the plot in ammonium culture was not significant; however, the value of the live cell fraction was within the range for the NO?3culture. The fraction of live vegetative cells in N2 culture was constant at all growth rates and the increase in the overall live cell fraction with growth rate was due entirely to an increase in live heterocysts. Live heterocysts comprised 3.5% of the total cells at a growth rate of 0.25 day?1 and increased to 6.3% at 0.75 day?1 with the ratio of live heterocysts to live vegetative cells linearly increasing with growth rate. The fraction of live vegetative cells was invariant in nitrate cultures us in N2cultures. The live heterocysts fraction also increased with growth rate in nitrate cultures, along with the live heterocysts : live vegetative cells ratio, but the level was lower than in N2cultures. DOC released from dead cells increased inversely with growth rate in N2from 36.4% of the total DOC at a growth rate of 0.75 day?1 to 54.15% at 0.25 day?1. The contribution of cell death to the total DOC production in nitrate and ammonium media was significantly less than that under N2DOC from dead cells consisted mainly of high-molecular-weight compounds, whereas DOC excreted from live cells was largely of low molecular weight. 相似文献