全文获取类型
收费全文 | 676篇 |
免费 | 41篇 |
国内免费 | 2篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 26篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 16篇 |
2017年 | 12篇 |
2016年 | 30篇 |
2015年 | 44篇 |
2014年 | 37篇 |
2013年 | 61篇 |
2012年 | 56篇 |
2011年 | 74篇 |
2010年 | 45篇 |
2009年 | 39篇 |
2008年 | 47篇 |
2007年 | 43篇 |
2006年 | 37篇 |
2005年 | 44篇 |
2004年 | 20篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1992年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有719条查询结果,搜索用时 125 毫秒
711.
Steffi Gaebler‐Schwarz Andrew Davidson Philipp Assmy Jixin Chen Joachim Henjes Eva‐Maria Nöthig Mirko Lunau Linda K. Medlin 《Journal of phycology》2010,46(5):1006-1016
Few members of the well‐studied marine phytoplankton taxa have such a complex and polymorphic life cycle as the genus Phaeocystis. However, despite the ecological and biogeochemical importance of Phaeocystis blooms, the life cycle of the major bloom‐forming species of this genus remains illusive and poorly resolved. At least six different life stages and up to 15 different functional components of the life cycle have been proposed. Our culture and field observations indicate that there is a previously unrecognized stage in the life cycle of P. antarctica G. Karst. This stage comprises nonmotile cells that range in size from ~4.2 to 9.8 μm in diameter and form aggregates in which interstitial spaces between cells are small or absent. The aggregates (hereafter called attached aggregates, AAs) adhere to available surfaces. In field samples, small AAs, surrounded by a colony skin, adopt an epiphytic lifestyle and adhere in most cases to setae or spines of diatoms. These AAs, either directly or via other life stages, produce the colonial life stage. Culture studies indicate that bloom‐forming, colonial stages release flagellates (microzoospores) that fuse and form AAs, which can proliferate on the bottom of culture vessels and can eventually reform free‐floating colonies. We propose that these AAs are a new stage in the life cycle of P. antarctica, which we believe to be the zygote, thus documenting sexual reproduction in this species for the first time. 相似文献
712.
713.
714.
Thermophilic microorganisms as well as acetogenic bacteria are both considered ancient. Interestingly, only a few species of bacteria, all belonging to the family Thermoanaerobacteraceae, are described to conserve energy from acetate formation with hydrogen as electron donor and carbon dioxide as electron acceptor. This review reflects the metabolic differences between Moorella spp., Thermoanaerobacter kivui and Thermacetogenium phaeum, with focus on the biochemistry of autotrophic growth and energy conservation. The potential of these thermophilic acetogens for biotechnological applications is discussed briefly.
相似文献715.
716.
Israel M. Scott Gabe M. Rubinstein Gina L. Lipscomb Mirko Basen Gerrit J. Schut Amanda M. Rhaesa W. Andrew Lancaster Farris L. Poole II Robert M. Kelly Michael W. W. Adams 《Applied and environmental microbiology》2015,81(20):7339-7347
Caldicellulosiruptor bescii grows optimally at 78°C and is able to decompose high concentrations of lignocellulosic plant biomass without the need for thermochemical pretreatment. C. bescii ferments both C5 and C6 sugars primarily to hydrogen gas, lactate, acetate, and CO2 and is of particular interest for metabolic engineering applications given the recent availability of a genetic system. Developing optimal strains for technological use requires a detailed understanding of primary metabolism, particularly when the goal is to divert all available reductant (electrons) toward highly reduced products such as biofuels. During an analysis of the C. bescii genome sequence for oxidoreductase-type enzymes, evidence was uncovered to suggest that the primary redox metabolism of C. bescii has a completely uncharacterized aspect involving tungsten, a rarely used element in biology. An active tungsten utilization pathway in C. bescii was demonstrated by the heterologous production of a tungsten-requiring, aldehyde-oxidizing enzyme (AOR) from the hyperthermophilic archaeon Pyrococcus furiosus. Furthermore, C. bescii also contains a tungsten-based AOR-type enzyme, here termed XOR, which is phylogenetically unique, representing a completely new member of the AOR tungstoenzyme family. Moreover, in C. bescii, XOR represents ca. 2% of the cytoplasmic protein. XOR is proposed to play a key, but as yet undetermined, role in the primary redox metabolism of this cellulolytic microorganism. 相似文献
717.
718.
Mirko Trutnau Mike Petzold Lysann Mehlig Martin Eschenhagen Katja Geipel Susann M��ller Thomas Bley Isolde R?ske 《Bioprocess and biosystems engineering》2011,34(3):287-295
Modelling of activated sludge processes is a commonly used technique to design and optimize wastewater treatment processes.
Since wastewater and activated sludge is characterized by chemical oxygen demand (COD) measurements, units of state variables
describing organic matter are expressed as equivalent amounts of COD. However, current procedures for measuring it have several
drawbacks, including the production of hazardous wastes, so the utility of other variables for characterizing the organic
load in modelling, such as total organic carbon (TOC), warrant re-evaluation. Other advantages of TOC over COD are that it
provides matrix-independent analytical results and it can be readily measured online. Proposals for TOC-based models were
made in the 1990s, but they seem to have sunk into obscurity. To re-assess the value of TOC for this purpose, we have recalculated
the EAWAG module for Bio-P removal coupled to the Activated Sludge Model No. 3 on a TOC basis, and tested it against data
acquired in batch experiments with four single carbon sources (acetate, glucose, citrate and casein). The batch test-based
calibrations showed a good match with experimental data, following modifications of the model to account for the anaerobic
volumes and retention times applied in the tests. 相似文献
719.