全文获取类型
收费全文 | 722篇 |
免费 | 63篇 |
国内免费 | 302篇 |
出版年
2024年 | 10篇 |
2023年 | 53篇 |
2022年 | 48篇 |
2021年 | 63篇 |
2020年 | 34篇 |
2019年 | 51篇 |
2018年 | 43篇 |
2017年 | 39篇 |
2016年 | 35篇 |
2015年 | 12篇 |
2014年 | 38篇 |
2013年 | 62篇 |
2012年 | 31篇 |
2011年 | 26篇 |
2010年 | 21篇 |
2009年 | 41篇 |
2008年 | 51篇 |
2007年 | 53篇 |
2006年 | 39篇 |
2005年 | 42篇 |
2004年 | 31篇 |
2003年 | 32篇 |
2002年 | 16篇 |
2001年 | 24篇 |
2000年 | 14篇 |
1999年 | 22篇 |
1998年 | 20篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 14篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有1087条查询结果,搜索用时 15 毫秒
101.
Use of genetically modified microorganisms (GEMs) for pollution abatement has been limited because of risks associated with their release in the environment. Recent developments in the area of recombinant DNA technologies have paved the way for conceptualizing "suicidal genetically engineered microorganisms" (S-GEMS) to minimize such anticipated hazards and to achieve efficient and safer bioremediation of contaminated sites. Our strategy of designing a novel S-GEM is based on the knowledge of killer-anti-killer gene(s) that would be susceptible to programmed cell death after detoxification of any given contaminated site(s). 相似文献
102.
Role of inhibitors of proteolytic enzymes in plant defense against phytopathogenic microorganisms 总被引:2,自引:0,他引:2
This review analyzes the literature on various mechanisms of proteolytic enzyme inhibitors involved in plant defense against attack by phytopathogenic microorganisms. The action of proteinase inhibitors from plants upon the enzymes from pathogenic microorganisms and viruses is reviewed. Considerable attention is given to the induction of proteinase inhibitors in plants in response to the invasion of pathogens. Some aspects of application of proteinase inhibitors in biotechnology for production of transgenic plants with enhanced resistance to diseases are discussed.Translated from Biokhimiya, Vol. 69, No. 11, 2004, pp. 1600–1606.Original Russian Text Copyright © 2004 by Valueva, Mosolov. 相似文献
103.
采用传统分离培养筛选微生物新活性物质的方法受到很大制约,自然界99%以上的微生物不能培养,其资源开发受到很大限制。环境微生物宏基因组技术应用避开了微生物分离纯培养问题,极大拓展了微生物资源的利用空间,增加获得新活性物质的机会和途径。本文着重介绍宏基因组的概念、研究策略包括DNA提取、文库构建与筛选等及在微生物活性物质筛选中的应用,并对宏基因组研究中存在的问题进行探讨。 相似文献
104.
Effects of long-term mineral fertilization and manuring on the biomass of arbuscular mycorrhizal fungi (AMF) were studied in a field experiment. Mineral fertilization reduced the growth of AMF, as estimated using both measurements of hyphal length and the signature fatty acid 16:1ω5, whereas manuring alone increased the growth of AMF. The results of AMF root colonization followed the same pattern as AMF hyphal length in soil samples, but not AMF spore densities, which increased with increasing mineral and organic fertilization. AMF spore counts and concentration of 16:1ω5 in soil did not correlate positively, suggesting that a significant portion of spores found in soil samples was dead. AMF hyphal length was not correlated with whole cell fatty acid (WCFA) 18:2ω6,9 levels, a biomarker of saprotrophic fungi, indicating that visual measurements of the AMF mycelium were not distorted by erroneous involvement of hyphae of saprotrophs. Our observations indicate that the measurement of WCFAs in soil is a useful research tool for providing information in the characterization of soil microflora. 相似文献
105.
V. V. Maksimov E. V. Shchetinina O. V. Kraykivskaya E. A. Maksimova 《Microbiology》2006,75(6):653-657
The survival rate, metabolic activity, and ability for growth of microbial communities of Lake Baikal have been first studied after exposure to extremely low temperatures (freeze-thawing) for different lengths of time. It has been shown that short-term freezing (1–3 days) inhibits the growth and activity of microbial communities. The quantity of microorganisms increased after 7-and 15-day freezing. In the periods of maximums, the total number of microorganisms in the test samples was twice as high as in the control. It was established that after more prolonged freezing the microorganisms required more time after thawing to adapt to new conditions. In the variants with 7-and 15-day freezing, the activities of defrosted microbial communities were three or more times higher than in the control. The survival rate and activity of Baikal microorganisms after freeze-thawing confirms the fact that the Baikal microbial communities are highly resistant to this type of stress impact. 相似文献
106.
一株生物絮凝剂产生菌的筛选及絮凝活性研究 总被引:10,自引:1,他引:9
从活性污泥中筛选到一株产絮凝剂的菌株WJ-100。该菌株产絮凝剂的适宜pH塑6.5。适宜温度为25℃~40℃,摇床速度为80~240r/min;Na^+、K^+、Ca^2+、Fe^3+均有较好的促絮凝作用,Ca^2+尤为显著;WJ-100以多种糖类为良好碳源,絮凝率达99.2%、99.8%甚至100%;该菌株在高岭土悬液pH2.0~10.0范围均有较好的絮凝效果。WJ-100在较大的pH、温度、碳源、摇床速度、搅拌速度等范围内均具有很高的絮凝活性,显示出重要的研究和应用价值。 相似文献
107.
V. N. Danilevich L. E. Petrovskaya E. V. Grishin 《Russian Journal of Bioorganic Chemistry》2006,32(6):521-528
The ability of buffer solutions containing low concentrations of nonionic detergents (Triton X-100, Tween 20, Brij 58, and Lubrol PX) and the anionic detergent sodium deoxycholate, as well as mixtures of these detergents with chaeotropes (urea and guanidine hydrochloride), to extract intracellular proteins of Gram-negative microorganisms (Escherichia coli and Pseudomonas aeruginosa) was studied. It was established that the solutions containing Triton X-100 and sodium deoxycholate and the mixtures of these detergents with urea are the most effective. It was shown that the extraction of proteins from bacterial cells under the studied conditions is not accompanied by a release of DNA into solution but is associated with extraction of low-molecular RNAs. The level of protein extraction reaches 80%. No disruption of the bacterial cell wall occurs during the extraction, and proteins probably penetrate through meshes of the murein network. The efficiencies of our buffer mixtures are close to or higher than that of the commercial reagent CelLytic B (Sigma, United States). The practical uses of the chaeotropic mixtures developed are discussed. 相似文献
108.
109.
Estrada-de los Santos P Martínez-Aguilar L López-Lara IM Caballero-Mellado J 《Systematic and applied microbiology》2012,35(5):310-314
A group of 20 bacterial strains was isolated from the rhizosphere of different agricultural plants growing in alkaline soils in the northeast of Mexico. The phylogenetic analysis of the 16S rRNA gene sequence from four strains showed that this novel group belonged to the Cupriavidus genus, with C. taiwanensis (~98.9%) and C. necator (~98.8%) as the closest species. However, DNA-DNA reassociation values were less than 20%. The novel group did not fix nitrogen and lacked nifH and nodA genes, unlike C. taiwanensis. Whole-cell protein patterns were highly similar among the 20 strains but different from the closest Cupriavidus species. BOX-PCR patterns were distinct among the 20 strains but also differed from other Cupriavidus type species. The major cellular fatty acids from strains ASC-732(T) and SLV-2362 were C(16:0), C(18:1) ω7c/12t/9t and C(16:1) ω7c and/or C(15:0) iso 2OH. The major polar lipids consisted of phosphatidylglycerol, cardiolipin, phosphatidylethanolamine, 2-hydroxylated-phosphatidylethanolamine and an unknown aminolipid. The DNA G+C content of strain ASC-732(T) was 66.8mol%. All 20 strains grew in the presence of 5-10mgmL(-1) arsenic, 1mgmL(-1) zinc, and 0.1mgmL(-1) copper. Consequently, the group of strains was considered to represent a novel species for which the name Cupriavidus alkaliphilus sp. nov. is proposed. The type strain is ASC-732(T) (=LMG 26294(T)=CIP 110330(T)). 相似文献
110.
厌氧微生物降解多环芳烃研究进展 总被引:2,自引:0,他引:2
多环芳烃(PAHs)是一类普遍存在于环境介质中的难降解有机污染物,相对于好氧微生物降解PAHs的研究,厌氧微生物降解PAHs的研究则相对较少.本文从厌氧微生物降解PAHs的研究背景,厌氧降解微生物的特点和不同厌氧降解还原反应体系的角度综述了厌氧微生物降解PAHs的概况;结合厌氧微生物降解萘和菲转化途径的介绍,推断了其降解机制的内在原因;同时通过总结影响厌氧微生物降解PAHs的主要因素(包括:PAHs的生物可利用性、外源营养物质的添加、外源电子受体的添加、特定厌氧降解菌的筛选强化和部分环境因素等),指出了制约降解进程的潜在限制因子;并对厌氧微生物降解PAHs研究目前存在的问题和未来的发展方向作了简述与展望. 相似文献