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71.
Akio Hagihara 《Population Ecology》1976,17(2):224-239
Summary The theories of the stochastic processes are applied to construct mathematical models for describing the processes of population
change as an ever changing the distribution of individuals in a space. These models consist of two mathematical expressions
which are named the spatial distribution probability function (Q
n
(t)) and the transition probability function (P
i,n
(t)), respectively. The former gives the spatial distribution at any future time. Given an actual spatial distribution at any
time, the latter function converts it to the spatial distribution at any future time. According to these models, we discussed
the time sequence of the mean crowding-mean density relation (Iwao andKuno, 1971) in some population processes such as mortality, birth, immigration, growth, and their combined processes. 相似文献
72.
Taizo Miura 《Population Ecology》1966,8(1):37-50
- Competitive influence of the isaza population on the ayu population was studied in Lake Biwa.
- The results of comparison of ecology of the two species suggest that interaction of ayu and isaza possibly occurs in cold season when there is no other important competitor.
- The significance of interspecific competition between them is evaluated as a factor controlling the rate of recruitment of juvenile through analysis of the Pre-war catch statistics.
- Presence of the compensation between the juvenile stage and the adult one relieve the ayu population of influence of interspecific competition which they will suffer in the stage of juvenile.
- Competitive processes which will be responsible for increase of mortality and reduction of individual growth are discussed.
73.
《Biocatalysis and Biotransformation》2013,31(5):255-268
This work is a case study on a process design for enzymatic peptide synthesis, which is based on and inspired by previously established data about the Alcalase-catalyzed coupling of an amino acid amide and a chemically synthesized activated N-protected amino acid carbamoylmethyl ester in near-anhydrous tetrahydrofuran. The choices with regard to Alcalase formulation, the type of reactor, method of controlling the water content, and whether or not to recycle the enzyme, are discussed. In addition, an estimate is given for the reactor size, volumes of solvent, amount of substrate, enzyme and molecular sieves, needed in order to meet a specific demand for peptides. We believe that this case study gives a good indication of the various choices that have to be made when designing a process for enzymatic peptide synthesis and the implications of these choices. 相似文献
74.
《Journal of biological education》2012,46(1):91-95
Process diagrams are important tools in biology for explaining processes such as protein synthesis, compound cycles and the like. The aim of the present study was to measure the ability to solve process-diagram problems in biology and its relationship with prior knowledge, spatial ability and working memory. For this purpose, we developed a test that represents process diagrams and adjacent tasks used in secondary education biology. Results show that the ability to solve process-diagram problems is correlated to prior knowledge, spatial abilities and visuospatial working memory capacity. A difference in impact of spatial skills was demonstrated for the level of cognitive demand when solving process-diagram problems. 相似文献
75.
Solid-state NMR reveals a close structural relationship between amyloid-β protofibrils and oligomers
We have studied tertiary contacts in protofibrils and mature fibrils of amyloid-β (Aβ) peptides using solid-state NMR spectroscopy. Although intraresidue contacts between Glu-22 and Ile-31 were found in Aβ protofibrils, these contacts were completely absent in mature Aβ fibrils. This is consistent with the current models of mature Aβ fibrils. As these intramolecular contacts have also been reported in Aβ oligomers, our measurements suggest that Aβ protofibrils are structurally more closely related to oligomers than to mature fibrils. This suggests that some structural alterations have to take place on the pathway from Aβ oligomers/protofibrils to mature fibrils, in agreement with a model that suggests a conversion of intramolecular hydrogen-bonded structures of Aβ oligomers to the intermolecular stabilized mature fibrils (Hoyer, W., Grönwall, C., Jonsson, A., Ståhl, S., and Härd, T. (2008) Proc. Natl. Acad. Sci. U.S.A. 105, 5099–5104). 相似文献
76.
Transient gene expression is frequently used in industry to rapidly generate usable quantities of a protein from cultured
cells. In gene therapy applications it is used to express a therapeutic protein in vivo. A quantitative assessment of the
expression kinetics is important because it enables optimization and control of culture conditions for higher productivity.
Previous experimental studies show a characteristic peak in average protein expression per cell after transfection followed
by an exponential decrease of the expressed protein. Here, we show that the exponential decrease in single cell expression
of enhanced Green Fluorescent Protein (eGfp) occurs in discrete steps. We attribute this to the absence of plasmid replication
and to symmetric partitioning of plasmid and eGfp between dividing cells. This is reflected in the total eGfp in the bioreactor,
which increased at a constant rate throughout the experiment. Additionally, the data provide a detailed time course of cell
physiology during recovery from electroporation. The time course of cell physiology precisely indicates when the culture shifts
growth phases. Furthermore, the data indicate two unique stationary phases. One type of stationary phase occurs when proliferation
ceases while cells decrease their cell size, maintain granularity, and mean eGfp content decreases. The second type occurs
when proliferation ceases while cells increase their cell size, increase granularity, and surprisingly maintain eGfp content.
The collected data demonstrate the utility of automated flow cytometry for unique bioreactor monitoring and control capabilities
in accordance with the US Food and Drug Administration’s Process Analytical Technology initiative. 相似文献
77.
Lawryńczuk M 《Bioprocess and biosystems engineering》2009,32(3):301-312
This paper describes the application of artificial neural networks to modelling and control of a continuous fermentor. A computationally
efficient nonlinear model predictive control (MPC) algorithm with nonlinear prediction and linearisation (MPC-NPL) which needs
solving on-line a quadratic programming problem is developed. It is demonstrated that the algorithm results in closed-loop
control performance similar to that obtained in nonlinear MPC, which hinges on full on-line non-convex optimisation. The computational
complexity of the MPC-NPL algorithm is shown, control accuracy and robustness are also demonstrated in the case of noisy measurements
and disturbances affecting the process. 相似文献
78.
Heat-shock protein glycoprotein (gp96) serves as a natural adjuvant for chaperoning antigenic peptide into the immune surveillance
pathway. In our laboratory, MethA tumor cell suspension culture process has been recently developed for gp96 production in
spinner flask. In this work, effects of dissolved oxygen tension (DOT) and agitation rate on this process were studied in
stirred-tank bioreactor. The optimal conditions for gp96 production were different with those for MethA tumor cell growth.
MethA tumor cell growth pattern was not much changed by various levels of DOT and agitation rate, while gp96 biosynthesis
was more sensitive to DOT and agitation rate. Compared with 50% of DOT, the production and specific productivity of gp96 was
increased by 27 and 66% at 10% of DOT, respectively. Compared with the agitation rate of 100 rpm, the production and volumetric
productivity of gp96 was increased by 48 and 144% at the agitation rate of 200 rpm, respectively. Low DOT (i.e., 10% of air
saturation) and high agitation rate (i.e., 200 rpm) were identified to be favorable for gp96 biosynthesis. The results of
this work might be useful to scale-up the bioprocess into the pilot scale. 相似文献
79.
Textile industry discharges a vast amount of unused synthetic dyes in effluents. The discharge of these effluents into rivers and lakes leads to a reduction in sunlight penetration in natural water bodies, which, in turn, decreases both photosynthetic activity and dissolved oxygen concentration rendering it toxic to living beings. This paper describes the decolorization potential of a local white rot fungus, Coriolus versicolor IBL-04 for practical industrial effluents collected from five different textile industries of Faisalabad, Pakistan. Screening of C. versicolor IBL-04 on five effluents showed best decolorization results (36.3%) for Arzoo Textile Industry (ART) effluent in 6 days followed by Crescent Textile Industry (CRT), Itmad Textile Industry (ITT), Megna Textile Industry (MGT) and Ayesha Textile Industry (AST) effluents. Optimization of different process parameters for ART effluent decolorization by C. versicolor IBL-04 showed that manganese peroxidase (MnP) (486 U/mL) was the lignolytic enzyme present in the culture filtrates with undetectable lignin peroxidase (LiP) and laccase. The MnP synthesis and effluent decolorization could be enhanced to 725 U/mL and 84.4%, respectively, with a significant time reduction to 3 days by optimizing pH and temperature and using 1% starch as a supplementary carbon source. 相似文献
80.
Demain AL 《Journal of industrial microbiology & biotechnology》2006,33(7):486-495
In order for a natural product to become a commercial reality, laboratory improvement of its production process is a necessity since titers produced by wild strains could never compete with the power of synthetic chemistry. Strain improvement by mutagenesis has been a major success. It has mainly been carried out by “brute force” screening or selection, but modern genetic technologies have entered the scene in recent years. For every new strain developed genetically, there is further opportunity to raise titers by medium modifications. Of major interest has been the nutritional control by induction, as well as inhibition and repression by sources of carbon, nitrogen, phosphate and end products. Both strain improvement and nutritional modification contribute to the new process, which is then scaled up by biochemical engineers into pilot scale and later into factory size fermentors. 相似文献