全文获取类型
收费全文 | 488篇 |
免费 | 29篇 |
专业分类
517篇 |
出版年
2023年 | 10篇 |
2022年 | 7篇 |
2021年 | 9篇 |
2020年 | 13篇 |
2019年 | 13篇 |
2018年 | 6篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 16篇 |
2014年 | 26篇 |
2013年 | 41篇 |
2012年 | 33篇 |
2011年 | 33篇 |
2010年 | 29篇 |
2009年 | 12篇 |
2008年 | 24篇 |
2007年 | 21篇 |
2006年 | 23篇 |
2005年 | 25篇 |
2004年 | 13篇 |
2003年 | 20篇 |
2002年 | 4篇 |
2001年 | 12篇 |
2000年 | 7篇 |
1999年 | 14篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有517条查询结果,搜索用时 0 毫秒
71.
72.
Sineshchekov OA Trivedi VD Sasaki J Spudich JL 《The Journal of biological chemistry》2005,280(15):14663-14668
We characterize changes in isomeric states of the retinylidene chromophore during light-dark adaptation and photochemical reactions of Anabaena (Nostoc) sp. PCC7120 sensory rhodopsin (ASR). The results show that ASR represents a new type of microbial rhodopsin with a number of unusual characteristics. The three most striking are: (i) a primarily all-trans configuration of retinal in the dark-adapted state and (ii) a primarily 13-cis light-adapted state with a blue-shifted and lower extinction absorption spectrum, opposite of the case of bacteriorhodopsin; and (iii) efficient reversible light-induced interconversion between the 13-cis and all-trans unphotolyzed states of the pigment. The relative amount of ASR with cis and trans chromophore forms depends on the wavelength of illumination, providing a mechanism for single-pigment color sensing analogous to that of phytochrome pigments. In addition ASR exhibits unusually slow formation of L-like and M-like intermediates, with a dominant accumulation of M during the photocycle. Co-expression of ASR with its putative cytoplasmic transducer protein shifts the absorption maximum and strongly decreases the rate of dark adaptation of ASR, confirming interaction between the two proteins. Thus ASR, the first non-haloarchaeal sensory rhodopsin characterized, demonstrates the diversity of photochemistry of microbial rhodopsins. Its photochromic properties and the position of its two ground state absorption maxima suggest it as a candidate for controlling differential photosynthetic light-harvesting pigment synthesis (chromatic adaptation) or other color-sensitive physiological responses in Anabaena cells. 相似文献
73.
74.
Host microbiomes play a critical role in host fitness and health. Whilst the current 'holobiont' concept framework has greatly expanded eco-evolutionary and functional understanding of host-microbiome interactions, the important role of biotic interactions and microbial loop (compositional linkage between soil, plant and animal) in shaping host-microbiome are poorly understood. We proposed an 'eco-holobiont' concept to fill the knowledge gap. 相似文献
75.
76.
Bacteriorhodopsin (BR) is an integral membrane protein found in "purple membrane" (the Archaea cell membrane) mainly in Halobacteria. This protein absorbs green light (wavelength 500-650 nm, with the absorption maximum at 568 nm) and converts it into an electrochemical gradient. This gradient in turn is used for ATP production. The ability of BR to convert light energy into chemical energy or sunlight into electricity has been used in different applications mainly optical appliances but also for therapeutic/medical applications and research. This review surveys some of these applications that have been patented in the last five years. 相似文献
77.
Michael?A?Ward Cynthia?M?Carlsson Mehul?A?Trivedi Mark?A?Sager Sterling?C?JohnsonEmail author 《BMC neurology》2005,5(1):23
Background
Obesity causes or exacerbates a host of medical conditions, including cardiovascular, pulmonary, and endocrine diseases. Recently obesity in elderly women was associated with greater risk of dementia, white matter ischemic changes, and greater brain atrophy. The purpose of this study was to determine whether body type affects global brain volume, a marker of atrophy, in middle-aged men and women. 相似文献78.
79.
Usdin K; Chevret P; Catzeflis FM; Verona R; Furano AV 《Molecular biology and evolution》1995,12(1):73-82
The single most difficult problem in phylogenetic analysis is deciding
whether a shared taxonomic character is due to common ancestry or one that
appeared independently due to convergence, parallelism, or reversion to an
ancestral state. Mammalian L1 retrotransposons undergo periodic
amplifications in which multiple copies of the elements are interspersed in
the genome. Because these elements apparently are transmitted only by
inheritance and are retained in the genome, a shared L1 amplification event
can only be an inherited ancestral character. We propose that L1
amplification events can be an excellent tool for analyzing mammalian
evolution and demonstrate here how we addressed several refractory problems
in rodent systematics using L1 DNA as a taxonomic character.
相似文献
80.