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排序方式: 共有898条查询结果,搜索用时 31 毫秒
891.
I. Bergmann K. Mundt M. Sontag I. Baumstark E. Nettmann M. Klocke 《Systematic and applied microbiology》2010
Quantitative real-time PCR (Q-PCR) is commonly applied for the detection of certain microorganisms in environmental samples. However, some environments, like biomass-degrading biogas fermenters, are enriched with PCR-interfering substances. To study the impact of the DNA extraction protocol on the results of Q-PCR-based analysis of the methane-producing archaeal community in biogas fermenters, nine different protocols with varying cell disruption and DNA purification approaches were tested. 相似文献
892.
T. Brányik A.A. Vicente J.M. Machado Cruz J.A. Teixeira 《Biotechnology letters》2001,23(13):1073-1078
A novel carrier obtained from spent grains, a brewing by-product, was used for brewing yeast immobilisation in a continuous bubble-column reactor. The multiple-layer cell adhesion to the carrier particles resulted in a maximum cell load of 430 mg dry cell g–1 dry carrier (d.c.). After 120 h of reactor operation, the cell load of DEAE-modified carrier was below 40 mg dry cell g–1 d.c. while the values for non-modified carrier reached at least 100 mg dry cell g–1 d.c. The changes in substrate composition on the rate of yeast attachment and on its stability were also studied. 相似文献
893.
Ganesh Kumar Arumugam Sekaran Ganesan Swarnalatha Somasundaram Prasad Rao Burusa 《World journal of microbiology & biotechnology》2005,21(6-7):999-1007
Summary The solid resinous product (SRP) containing unsaturated/saturated dicarboxylic acid residues, phthalic acid and maleic acid
is discharged as a solid waste during cracking of benzene over vanadium at temperatures above 500°C in the dicarboxylic acid
manufacturing industry. In the present study the solid waste was diluted with water to a concentration of 0.5% w/v for microbial
degradation. The waste was fermented in a reactor containing mesoporous activated carbon on which was immobilized Saccharomyces cerevisiae at an optimum residence time of 24 h at pH 6.5. The immobilized-yeast-treated samples were further treated in an upflow anaerobic
reactor at an hydraulic retention time (HRT) of 0.1038 days at a hydraulic flow rate of 7.34 × 10−3 m3/day and chemical oxygen demand (COD) loading rate of 2.19 kg/m3/day. The pathway followed in the degradation of dicarboxylic acid into end products by anaerobic metabolism in the yeast
cell fermentor and in the upflow anaerobic reactor was confirmed through HPLC, Fourier transform infra red spectroscopy and
proton and 13C NMR spectroscopy. 相似文献
894.
Martin Fussenegger Dieter Fassnacht Regine Schwartz James A. Zanghi Michael Graf James E. Bailey Ralf Pörtner 《Cytotechnology》2000,32(1):45-61
Using multicistronic expression technology we generated a stable Chinese hamster ovary (CHO) cell line (MG12) expressing a model secreted heterologous glycoprotein, the secreted form of the human placental alkaline phosphatase (SEAP), and bcl-2, best known as an apoptosis inhibitor, in a tetracycline-repressible dicistronic configuration. In batch cultivations in serum-containing medium, MG12 cells reached twice the final viable cell density when Bcl-2 was overexpressed (in the absence oftetracycline) compared to MG12 populations culturedunder tetracycline-containing conditions (bcl-2repressed). However, bcl-2-expressing MG12 cellsshowed no significant retardation of the decline phasecompared to batch cultures in which the dicistronicexpression unit was repressed.Genetic linkage of bcl-2 expression with the reporter protein SEAP in our multicistronic construct allowed online monitoring of Bcl-2 expression over an extended, multistage fixed-bed bioreactor cultivation. The cloned multicistronic expression unit proved to be stable over a 100 day bioreactor run. CHO MG12 cells in the fixed-bed reactor showed a drastic decrease in the release of DNA into the culture supernatant under conditions of reduced tetracycline (and hencederepressed SEAP and bcl-2 overexpression). This observation indicated enhanced robustness associated with bcl-2 overexpression, similar to recent findings for constitutive Bcl-2-overexpressing hybridoma cells under the same bioprocess conditions. These findings indicate, in these serum-containing CHO cell cultures, that overexpression of Bcl-2 results in desirable modifications in culture physiology. 相似文献
895.
F. P. Cuperus S. Th. Bouwer G. F. H. Kramer J. T. P. Derksen 《Biocatalysis and Biotransformation》1994,9(1):89-96
Stabilization of Upases by immobilization on different polymer materials has been shown. The Upases were used for triglyceride hydrolysis and the synthesis of the chemically very reactive peroxycarboxylic acids. Using in-situ produced peracids, epoxides were formed from oleic acid. Inactivation of the enzymes is probably due the substrate hydrogen peroxide. 相似文献
896.
A systematic experimental analysis of the parameters affecting the behaviour of a Trickle Bed Reactor (TBR) was performed. Lignin peroxidases (LiPs) were produced in the reactor by Phanerochaete chrysosporium entrapped in a Ca-alginate film covering ceramic supports (Berl saddles). Gas and liquid velocity, liquid flow regime, and thickness of encapsulating matrix were experimentally investigated. Reactor productivity and biological activity were considered as representative of reactor performance and evaluated by six probe parameters to take into account different process system configurations, i.e. single LiP extraction, multiple LiP extraction every 24 h and in vivo applications. Liquid fluid dynamics were the critical phenomena affecting LiPs production; the ranges of gas and liquid superficial velocity influencing the reactor performance were also identified. Alginate film thickness was shown to influence specific biomass activity but a limited impact on reactor productivity was verified. 相似文献
897.
David Penny 《Biology & philosophy》2005,20(4):633-671
Life appears to be a natural property of matter, but the problem of its origin only arose after early scientists refuted continuous
spontaneous generation. There is no chance of life arising ‘all at once’, we need the standard scientific incremental explanation
with large numbers of small steps, an approach used in both physical and evolutionary sciences. The necessity for considering
both theoretical and experimental approaches is emphasized. After describing basic principles that are available (including
the Darwin-Eigen cycle), the search for origins is considered under four main themes. These are the RNA-world hypothesis;
potential intermediates between an RNA-world and a modern world via the evolution of protein synthesis and then of DNA; possible alternatives to an RNA-world; and finally the earliest stages
from the simple prebiotic systems to RNA. The triplicase/proto-ribosome theory for the origin of the ribosome is discussed
where triples of nucleotides are added to a replicating RNA, with the origin of a triplet code well-before protein synthesis
begins. The length of the code is suggested to arise from the early development of a ratchet mechanism that overcomes the
problem of continued processivity of an RNA-based RNA-polymerase. It is probable that there were precursor stages to RNA with
simpler sugars, or just two nucleotides, but we do not yet know of any better alternatives to RNA that were likely to arise
naturally. For prebiotic stages (before RNA) a flow-reactor model is suggested to solve metabolism, energy gradients, and
compartmentation simultaneously – thus the intense interest in some form of flow reactor. If an autocatalytic cycle could
arise in such a system we would be major steps ahead. The most likely physical conditions for the origin of life require further
clarification and it is still unclear whether the origin of life is more of an entropy (information) problem (and therefore
high temperatures would be detrimental), rather than a kinetic problem (where high temperatures may be advantageous). 相似文献
898.
Biodegradation of phenol and chlorophenols with defined mixed culture in shake-flasks and a packed bed reactor 总被引:7,自引:0,他引:7
Jung-Hwa Kim Kyung-Keun Oh Sung-Taik Lee Seung-Wook Kim Suk-In Hong 《Process Biochemistry》2002,37(12):1367-1373
Pseudomonas testosteroni CPW301 degraded phenol and 4-chlorophenol simultaneously, but degradation rates of these compounds were affected by 4-chlorophenol. Phenol increased the cell concentration and therefore the degradation efficiency of 4-chlorophenol was improved. Pseudomonas solanacearum TCP114 could degrade only 2,4,6-trichlorophenol. A defined mixed culture of P. testosteroni CPW301 and P. solanacearum TCP114 could treat phenol, 4-chlorophenol, and 2,4,6-trichlorophenol completely and overcome the inhibition of substrates to other microorganisms. The degradation capacity of the packed bed reactor (PBR) was higher than that of the continuous stirred tank reactor, but the PBR was unsuitable for oxygen-sensitive microorganisms. 相似文献