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231.
Protochlorophyllide-binding proteins were investigated and possible changes in the pigment-protein association during light-induced chlorophyll synthesis were analyzed. Three major results were obtained. (1) Four protochlorophyllide-binding polypeptides were separated electrophoretically on polyacrylamide gels and visualized by their fluorescence. The number and size of these protochlorophyllide-binding proteins isolated from darkgrown and illuminated plants were not affected by light. (2) The association of pigment with these proteins was studied using exogenous [3H]protochlorophyllide as substrate in an NADPH-dependent in vitro chlorophyll synthesis assay. It was found that a constant exchange of protein-bound and free pigment occurs and that freshly synthesized chlorophyllide does not accumulate on any of the four pigment-binding proteins in vitro. (3) NADPH does not affect the amount of pigment bound to protein in vitro, even during chlorophyll synthesis which occurred only in the presence of NADPH. 相似文献
232.
Activity-dependent fluorescent labeling of bacteria that degrade toluene via toluene 2,3-dioxygenase
Alternative substrates for the toluene 2,3-dioxygenase pathway of several pseudomonads served as enzyme-activity-dependent
fluorescent probes for the bacteria. Phenylacetylene and cinnamonitrile were transformed to fluorescent and brightly colored
products by Pseudomonas putida F1, Pseudomonas fluorescens CFS215, and Burkholderia (Pseudomonas) strain JS150. Active bacteria transformed phenylacetylene, producing bright yellow solutions containing the putative product
2-hydroxy-6-oxo-7-octyn-2,4-dienoate. Transformation of cinnamonitrile resulted in bright orange solutions due to accumulation
of the putative product 2-hydroxy-6-oxo-8-cyanoocta-2,4,7-trienoate. Chemical and physical properties of the products supported
their identification, which indicated that the first three enzymes of the pathway catalyzed product formation. Phenylacetylene
labeled bacteria with green fluorescence emission; bacteria were concentrated on black 0.2-μm-pore-size polycarbonate filters
containing polyvinylpyrrolidone (PVP) as a wetting agent. Bacteria labeled with cinnamonitrile were fluorescent orange; labeling
was effective with bacteria trapped on PVP-free polycarbonate filters. Production of the enzymes involved in labeling of P. putida F1 and P. fluorescens CFS215 was induced by growth (on arginine) in the presence of toluene; cells grown on arginine without toluene were not labeled.
Labeling of P. putida F1 by phenylacetylene was inhibited by toluene, indicating that the same enzymatic pathway was required for transformations
of both substrates. Bacteria expressing other toluene-degrading enzymatic pathways were not fluorescently labeled with phenylacetylene.
Received: 30 July 1997 / Received revision: 1 November 1997 / Accepted: 21 November 1997 相似文献
233.
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235.
Seedlings of spring barley,Hordeum vulgare L. cv. Mirena, were grown in a controlled environment chamber at high (HI: 122 Wm?2) and low (LI: 28 Wm?2) irradiance in the complete Richter’s nutrient solution (R) or in solution lacking either phosphorus (R -P) or nitrogen (R -N). The experiment was terminated 15 days after sowing when plants (R-N) at HI ceased to grow. At that time the dry mass of one plant was 449.8 mg, 145.7 mg and 116.8mg at HI and 203.4 mg, 110.1 mg and 91.0 at LI for R, (R-P) and (R-N), respectively. Deficiency of P and especially N reduced the size of loaf area more under HI than under LI conditions. Specific dry mass of leaves was the highest in R-N plants. The values of relative growth rate and assimilation rate are presented. Interaction of the effects of deficiency of mineral nutrients and irradiance during cultivation should be analyzed in further experiments for determination of optimum conditions for utilization of mineral nutrients. 相似文献
236.
Mahesh A. Rege David R. Mills James N. Petersen Yunwei Sun David R. Yonge William A. Apel 《Biotechnology Techniques》1998,12(12):913-918
An approach to estimate the parameters needed to describe the performance of a column packed with BioSepTM beads is presented. These parameters, which characterize the transport of materials through the column, have been estimated from experimental residence time distribution (RTD) data using both porous and non-porous beads. A laboratory-scale column was used to obtain the experimental data using several ionic species. © Rapid Science Ltd. 1998 相似文献
237.
The role of proteolysis during the light-induced rapid decrease of the NADPH: protochlorophyllide oxidoreductase in barley was studied. A proteolytic activity with a pH optimum of 4.5 was present in a plastid preparation of etiolated barley seedlings. No other proteolytic activity could be detected. The temperature optimum for the proteolysis was 50°C, and the highest specific activity was measured with hemoglobin as the substrate. In contrast to previous proposals, no evidence for the specific involvement of this protease was found during the light-induced transformation of etioplasts to chloroplasts. 相似文献