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排序方式: 共有322条查询结果,搜索用时 15 毫秒
31.
Dengue is a public health problem of global significance for which there is neither an effective antiviral therapy nor a preventive vaccine. The envelope protein of dengue virus is the major antigen to elicit neutralizing antibody response and protective immunity in hosts. Optimization of culture media was carried out for enhanced production of recombinant dengue virus type 3 envelope domain III (rDen 3 EDIII) protein in E. coli. Further, batch and fed-batch cultivation process were also developed in optimized medium. After fed-batch cultivation, the dry cell weight was about 22.80 g/L of culture. The rDen 3 EDIII protein was purified using immobilized metal affinity chromatography. This process produced ~649 mg of purified rDen 3 EDIII protein per liter of culture. The purity of the protein was determined by SDS-PAGE analysis and the reactivity was checked by Western blotting as well as ELISA. These results show that the purified protein may be used for the dengue diagnosis or further prophylactic studies for dengue infection. 相似文献
32.
Joyce P Abdo Z Ponciano JM De Gelder L Forney LJ Top EM 《Journal of mathematical biology》2005,50(6):645-662
Antibiotic resistant bacteria are a constant threat in the battle against infectious diseases. One strategy for reducing their effect is to temporarily discontinue the use of certain antibiotics in the hope that in the absence of the antibiotic the resistant strains will be replaced by the sensitive strains. An experiment where this strategy is employed in vitro [5] produces data which showed a slow accumulation of sensitive mutants. Here we propose a mathematical model and statistical analysis to explain this data.The stochastic model elucidates the trend and error structure of the data. It provides a guide for developing future sampling strategies, and provides a framework for long term predictions of the effects of discontinuing specific antibiotics on the dynamics of resistant bacterial populations.This Research is part of the Initiative in Bioinformatics and Evolutionary Studies (IBEST) at the University of Idaho. Funding was provided by NSF EPSCoR EPS-0080935, NSF EPSCoR, EPS-0132626, and NIH NCRR grant NIH NCRR- 20RR016448. Paul Joyce is also funded by NSF DEB-0089756, and NSF DMS-0072198. 相似文献
33.
EEG是由大脑产生的非线性时间序列,体现出混沌行为。近年来迅速发展的非线性动力学理论为脑电信号分析开创了一个新的领域。本文综述了近年来非线性动力学在脑电信号研究中(睡眠阶段,麻醉深度,认知过程,精神分裂,痴呆及癫痫)的进展,以期对脑神经动力学有更好的理解。 相似文献
34.
Metabolically-engineered Escherichia coli strains were developed by cloning poly-γ-glutamic acid (γ-PGA) biosynthesis genes, consisting of pgsB, pgsC and pgsA, from Bacillus subtilis The metabolic and regulatory pathways of γ-PGA biosynthesis in E. coli were analyzed by DNA microarray. The inducible trc promoter and a constitutive promoter (PHCE) derived from the d-amino acid aminotransferase (D-AAT) gene of Geobacillus toebii were employed. The constitutive HCE promoter was more efficient than inducible trc promoter for the expression of γ-PGA biosynthesis genes. DNA microarray analysis showed that the expression levels of several NtrC family genes, glnA, glnK, glnG, yhdX, yhdY, yhdZ, amtB, nac, argT and cbl were up-regulated and sucA, B, C, D genes were down-regulated. When (NH4)2SO4 was added at 40 g/l into the feeding solution, the final γ-PGA concentration reached 3.7 g/l in the fed-batch culture of recombinant E. coli/pCOpgs. 相似文献
35.
Plants are becoming commercially acceptable for recombinant protein production for human therapeutics, vaccine antigens, industrial enzymes, and nutraceuticals. Recently, significant advances in expression, protein glycosylation, and gene-to-product development time have been achieved. Safety and regulatory concerns for open-field production systems have also been addressed by using contained systems to grow transgenic plants. However, using contained systems eliminates several advantages of open-field production, such as inexpensive upstream production and scale-up costs. Upstream technological achievements have not been matched by downstream processing advancements. In the past 10 years, the most research progress was achieved in the areas of extraction and pretreatment. Extraction conditions have been optimized for numerous proteins on a case-by-case basis leading to the development of platform-dependent approaches. Pretreatment advances were made after realizing that plant extracts and homogenates have unique compositions that require distinct conditioning prior to purification. However, scientists have relied on purification methods developed for other protein production hosts with modest investments in developing novel plant purification tools. Recently, non-chromatographic purification methods, such as aqueous two-phase partitioning and membrane filtration, have been evaluated as low-cost purification alternatives to packed-bed adsorption. This paper reviews seed, leafy, and bioreactor-based platforms, highlights strategies for the primary recovery and purification of recombinant proteins, and compares process economics between systems. Lastly, the future direction and research needs for developing economically competitive recombinant proteins with commercial potential are discussed. 相似文献
36.
José Rivera‐Utrilla María I. Bautista‐Toledo Manuel Sánchez‐Polo José D. Méndez‐Díaz 《Engineering in Life Science》2012,12(1):113-116
Successful surfactant removal from wastewater is often limited by the high concentration of the surfactant. The use of advanced oxidation processes can be the key to aid biological treatment of water containing high amounts of surfactants. The present study analyzes the biodegradation of the anionic surfactant sodium dodecylbenzenesulfonate (SDBS) and the effects of its combination with ozonation. SDBS pre‐ozonation favors the metabolism by microorganisms. Experimental results indicate that the application of a concentration of up to 60 μM of ozone for 60 min, prior to contact with microorganisms, increases the percentage of SDBS removed by biodegradation alone. These results demonstrate that the removal of SDBS and of the total organic carbon is increased by the consecutive use of ozonation and biodegradation. 相似文献
37.
政府使用公共财政投资建设公益性的工程,需遵守一定的审批与管理流程。由于缺少园林工程投资估算指标体系,以及园林工程特有的艺术性,使审批流程与设计流程产生了一些矛盾。审批过程中,评审者关注投资的合理性,设计者关注园林美学观感,两者的不同立场导致对部分园林绿地建设内容必要性的分歧。为了在保证建设资金投入合理性前提下最大限度地实现园林绿地的完整功能与艺术水平,对有关的问题进行梳理,提出平衡设计与评审的原则,并强调在审批与建设过程中各方面调整思维方式,进行换位思考的必要性。 相似文献
38.
39.
Evaluating the biodegradation of aromatic hydrocarbons by monitoring of several functional genes 总被引:1,自引:0,他引:1
Various microbial activities determine the effectiveness of bioremediation processes. In this work, we evaluated the feasibility
of gene array hybridization for monitoring the efficiency of biodegradation processes. Biodegradation of 14C-labelled naphthalene and toluene by the aromatic hydrocarbon-degrading Pseudomonas putida F1, P. putida mt-2 and P. putida G7 was followed in mixed liquid culture microcosm by a preliminary, nylon membrane-based gene array. In the beginning of
the study, toluene was degraded rapidly and increased amount of toluene degradation genes was detected by the preliminary
gene array developed for the study. After toluene was degraded, naphthalene mineralization started and the amount of naphthalene
degradation genes increased as biodegradation proceeded. The amount of toluene degradation genes decreased towards the end
of the study. The hybridization signal intensities determined by preliminary gene array were in good agreement with mineralization
of naphthalene and toluene and with the amount of naphthalene dioxygenase and toluene dioxygenase genes quantified by dot
blot hybridization. The clear correlation between the results obtained by the preliminary array and the biodegradation process
suggests that gene array methods can be considered as a promising tool for monitoring the efficiency of biodegradation processes. 相似文献
40.
The stability of Pseudomonas putida F1, a strain harbouring the genes responsible for toluene degradation in the chromosome was evaluated in a bioscrubber under
high toluene loadings and nitrogen limiting conditions at two dilution rates (0.11 and 0.27 h−1). Each experiment was run for 30 days, period long enough for microbial instability to occur considering previously reported
studies carried out with bacterial strains encoding the catabolic genes in the TOL plasmid. At all tested conditions, P. putida F1 exhibited stable performance as shown by the constant values of the specific toluene degradation yield, CO2 produced versus toluene degraded yield, and biomass concentration within each steady state. Benzyl alcohol, a curing agent
causing TOL plasmid deletion in Pseudomonas strains, was present in the cultivation medium as a result of the monooxygenation of toluene by the diooxygenase system of
P. putida F1. However, no mutant population growing at the expense of the extracellular excreted carbon or lysis products was established
in the chemostat as confirmed by the constant dissolved total organic carbon (TOC) concentration and fraction of toluene degrading
cells (approx. 100%). In addition, batch experiments conducted with both lysis substrate and toluene simultaneously confirmed
that P. putida F1 preferentially consumed toluene rather than extracellular excreted carbon. 相似文献