全文获取类型
收费全文 | 647篇 |
免费 | 50篇 |
国内免费 | 33篇 |
专业分类
系统科学 | 11篇 |
丛书文集 | 9篇 |
教育与普及 | 5篇 |
理论与方法论 | 3篇 |
现状及发展 | 17篇 |
综合类 | 677篇 |
自然研究 | 8篇 |
出版年
2024年 | 4篇 |
2023年 | 15篇 |
2022年 | 23篇 |
2021年 | 27篇 |
2020年 | 19篇 |
2019年 | 18篇 |
2018年 | 16篇 |
2017年 | 22篇 |
2016年 | 22篇 |
2015年 | 21篇 |
2014年 | 41篇 |
2013年 | 32篇 |
2012年 | 56篇 |
2011年 | 44篇 |
2010年 | 28篇 |
2009年 | 51篇 |
2008年 | 33篇 |
2007年 | 45篇 |
2006年 | 39篇 |
2005年 | 26篇 |
2004年 | 24篇 |
2003年 | 17篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
排序方式: 共有730条查询结果,搜索用时 31 毫秒
31.
微生物驱油数学模型 总被引:14,自引:3,他引:11
根据微生物生长动力学,建立了微生物生长、基质消耗和代谢产物生成方程。在考虑菌体、基质、产物扩散和吸附的基础上,用物质平衡方法建立了菌体、基质和产物的运移方程。以多孔介质的毛细管模型为基础,建立了由于微生物吸附引起的孔隙度和渗透率变化方程。考虑到微生物作用对流体性质的影响,建立了油、水粘度和油、气、水管力方程。根据黑油模型建立了三维、三相、多组分基质与产物的微生物驱油数学模型。计算结果表明,所建模型能较好地计算出微生物生长曲线、代谢曲线、基质消耗曲线和微生物运移浓度曲线,与实验值有较好的一致性。这些模型综合考虑了微生物的生化特性、微生物作用对岩石、流体性质的影响以及油、气、水的渗流规律,是一个比较完整的微生物驱油数学模型。 相似文献
32.
胡建 《上饶师范学院学报》2001,21(5):1-6
我国在建设社会主义市场经济价值系统的过程中,可以借鉴和扬弃西方“个性主义“的普遍人类价值因素.在社会层面,借鉴吸收卢梭关于“自由个人构成合理共同体“的思想,克服旧价值观“整体主义“泯灭个性自由的痼疾;在政治层面,借鉴吸取洛克“社会契约论“的民主法制精神,消解旧价值观以“权威主义“剥夺个人主体地位的顽症;在伦理层面,借鉴吸收康德“绝对命令说“的道德精髓,清除旧价值观以“私德至上“否绝个人正当利益的弊端.目前,我们应当看到“个性主义“因其阶级性时代性所限,有可能导致个人主体性的异化,滑向极端利己主义,对此,只能以马克思关于“个人与社会统一为本位“的“人类解放“价值观对其补偏纠弊. 相似文献
33.
Pathogenic enterococci: new developments in the 21st century 总被引:8,自引:0,他引:8
Tendolkar PM Baghdayan AS Shankar N 《Cellular and molecular life sciences : CMLS》2003,60(12):2622-2636
Enterococci, traditionally viewed as Gram-positive commensal bacteria inhabiting the alimentary canals of humans and animals, are now acknowledged to be organisms capable of causing life-threatening infections in humans, especially in the nosocomial environment. The existence of enterococci in such a dual role is facilitated, at least in part, by its intrinsic and acquired resistance to virtually all antibiotics currently in use. Beginning with the initial identification of a streptococci of fecal origin in the late 19th century, enterococci have been studied for over a century now. A number of comprehensive reviews during this time have addressed various aspects of enterococci, including classification, biology, virulence, antibiotic resistance and so on. This review specifically addresses the important advances in the field of enterococcal research that have occurred since the beginning of the 21st century. Most notable among these developments have been the insights into enterococcal genomes and pathogenicity.Received 10 April 2003; received after revision 31 May 2003; accepted 3 June 2003 相似文献
34.
油樟叶内生真菌的多样性研究 总被引:2,自引:0,他引:2
采取在马铃薯培养基上加无菌油樟(Cinnamomum longepaniculatum N.Chao ex H.W.Li)叶汁液作为分离培养基的办法,从油樟树叶中分离到24株内生真菌,经过鉴定,其分属于子囊菌纲的双足囊菌属(Dipodascus Lagerh.)、拟指突孢曲霉属(Emericellopsis J.F.H.Beyma)和半知菌类的花核菌属(Anthina Fr.)、青霉属(Penicillium Link)、组丝核菌属(Phacodium Pers.)、茎叶核菌属(Ectostroma Fr.)、地霉(Geotrichum Link)、皮核菌(Acinula Fr.)、团丝核菌(Papulaspora Preuss)、发菌(Capillaria Pers.)、峡串孢霉(Paepalopsis J.G.Khn)、小卵孢霉(Ovularia Sacc.)、卵形孢霉(Oospora Wallr.)、稀丝头孢霉(Haplotrichum Link)、单梗曲霉(Briarea Corda)等15个属,且以无孢菌居多,表现出较为丰富的类群(物种)多样性. 相似文献
35.
PENG XiaoTong ZHOU HuaiYang WU ZhiJun JIANG Lei TANG Song YAO HuiQiang 《科学通报(英文版)》2007,52(3):367-379
Microbial mats in two hot springs in South China were sampled for the research of mineralization of microbes and its mechanism by the methods of geology and modern biology. The results show that hot spring microbes have the key capability for enrichment of Si, Al, Fe, Ca and other elements, and the microbes are also crucial for the formation of SiO2, CaCO3, clay and so on. The extracellular polymeric substances (EPS) play important roles in the process of mineralization of hot spring microbes, which mainly takes place in the layer of EPS outside cell wall or sheath of cyanobacteria. The sheath outside cell wall, which keeps the normal metabolism of cyanobacteria during the process of mineralization on its surface, is also considerable for the biomineralization of cyanobacteria. According to structure and mineralization characteristics of two microbial mats, the process of mineralization can be divided into three stages, namely, early surface mineralization, middle degradation mineralization, and late des- quamation of mineral. The above conclusions are significant for comprehension of the process of mineralization, the process of deposition and the preservation of microfossil in modern and ancient extreme environments. 相似文献
36.
要玲 《科技情报开发与经济》2007,17(12):186-187
以处理高岭土悬浊液和池底污泥配制成的废液为基础,测定了其絮凝性,得出各种废水的最佳处理条件,探讨了金属阳离子对微生物絮凝性的影响。 相似文献
37.
朱鸿林 《广西民族大学学报》2007,(3)
讨论了19世纪末20世纪初修订的越南北部村社的成文乡规民约(券例)中的村社社会民俗,以及这些民俗所反映的一些时代问题。对这些乡约的研究将有助于加深对越南村社的认识。 相似文献
38.
张旺壁 《科技情报开发与经济》2007,17(32):171-173
介绍了国内外绿僵菌资源的开发现状以及山西省在绿僵菌研究方面所做的工作,阐述了绿僵菌菌剂中试生产基地建设项目的计划目标、主要研究内容、实施年限、经费预算、必要的支撑条件、组织措施及实施方案。 相似文献
39.
Battery waste is one of the most destructive hazards to our environment,especially to the soil.In order to understand the effects of the battery waste on the microbial communities in soil,microcosm soils were treated with the powder made from the battery waste.Microbial biomass and respiration were measured after 15,30,45,and 60 days of the treatment,and catabolic capability and Bi- olog profile were determined after 60 days.Microbial biomass was declined by all treatments,while microbial respiration and catabolic ca- pability were enhanced.Although microbial biomass recovered after a period of incubation,microbial respiratory quotient,catabolic capa- bility and community structure remained significantly affected.Our results also suggest that microbial respiratory quotient and Biolog pa- rameters are more sensitive than microbial biomass to the battery stress on bioavailability. 相似文献
40.
Establishing interdependency and community among people may be the solution to reestablishing or creating a tighter fabric of support for childrens' development, for building cultural democracy and a democratic state. This paper attempts to create a bridge between education and the construction of sustainable democratic communities in education, as a basis for building a public philosophy. Ultimately, sustainable democratic educational communities may address the concerns of today and tomorrow and build sustainable democratic communities in the larger global society. 相似文献