全文获取类型
收费全文 | 1122篇 |
免费 | 93篇 |
国内免费 | 52篇 |
出版年
2024年 | 5篇 |
2023年 | 24篇 |
2022年 | 26篇 |
2021年 | 42篇 |
2020年 | 33篇 |
2019年 | 54篇 |
2018年 | 40篇 |
2017年 | 49篇 |
2016年 | 58篇 |
2015年 | 45篇 |
2014年 | 47篇 |
2013年 | 60篇 |
2012年 | 43篇 |
2011年 | 47篇 |
2010年 | 28篇 |
2009年 | 92篇 |
2008年 | 87篇 |
2007年 | 72篇 |
2006年 | 58篇 |
2005年 | 37篇 |
2004年 | 34篇 |
2003年 | 34篇 |
2002年 | 25篇 |
2001年 | 32篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1976年 | 4篇 |
1974年 | 2篇 |
1973年 | 7篇 |
1971年 | 3篇 |
排序方式: 共有1267条查询结果,搜索用时 15 毫秒
131.
Vanesa Nahir?ak Natalia Inés Almasia Horacio Esteban Hopp Cecilia Vazquez-Rovere 《Plant signaling & behavior》2012,7(8):1004-1008
Snakin/GASA proteins are widely distributed among plant species. They are expressed in different plant organs with high tissue and temporal specificity, and their subcellular localization varies among the different members. Interestingly, all of them maintain 12 cysteines of the C-terminus in highly conserved positions of the aminoacid sequences that are essential for their biochemical activity and probably responsible for their protein structure. Despite their common features, their functions are not completely elucidated and little is known about their mode of action. This review focuses on the current knowledge about this intriguing family of peptides and advances comprising gene regulation analyses, expression pattern studies and phenotypic characterization of mutants and transgenic plants. Furthermore, we discuss the roles of Snakin/GASA proteins in several aspects of plant development, plant responses to biotic or abiotic stress and their participation in hormone crosstalk and redox homeostasis. 相似文献
132.
133.
134.
135.
Fatty acid unsaturation,mobilization, and regulation in the response of plants to stress 总被引:1,自引:0,他引:1
Upchurch RG 《Biotechnology letters》2008,30(6):967-977
Stress acclimating plants respond to abiotic and biotic stress by remodeling membrane fluidity and by releasing α-linolenic
(18:3) from membrane lipids. The modification of membrane fluidity is mediated by changes in unsaturated fatty acid levels,
a function provided in part by the regulated activity of fatty acid desaturases. Adjustment of membrane fluidity maintains
an environment suitable for the function of critical integral proteins during stress. α-Linolenic acid, released from membrane
lipid by regulated lipase activity, is the precursor molecule for phyto-oxylipin biosynthesis. The modulation of chloroplast
oleic acid (18:1) levels is central to the normal expression of defense responses to pathogens in Arabidopsis. Oleic (18:1) and linolenic (18:2) acid levels, in part, regulate development, seed colonization, and mycotoxin production
by Aspergillus spp. 相似文献
136.
Joubès J Raffaele S Bourdenx B Garcia C Laroche-Traineau J Moreau P Domergue F Lessire R 《Plant molecular biology》2008,67(5):547-566
As precursors of wax compounds, very long chain fatty acids participate in the limitation of non-stomatal water loss and the prevention of pathogen attacks. They also serve as energy storage in seeds and as membrane building blocks. Their biosynthesis is catalyzed by the acyl-CoA elongase, a membrane-bound enzymatic complex containing four distinct enzymes (KCS, KCR, HCD and ECR). Twenty-one 3-ketoacyl-CoA synthase (KCS) genes have been identified in Arabidopsis thaliana genome. In this paper we present an overview of the acyl-CoA elongase genes in Arabidopsis focusing on the entire KCS family. We show that the KCS family is made up of 8 distinct subclasses, according to their phylogeny, duplication history, genomic organization, protein topology and 3D modelling. The analysis of the subcellular localization in tobacco cells of the different subunits of the acyl-CoA elongase shows that all these proteins are localized in the endoplasmic reticulum demonstrating that VLCFA production occurs in this compartment. The expression patterns in Arabidopsis of the acyl-CoA elongase genes suggest several levels of regulations at the tissular or organ level but also under stress conditions suggesting a complex organization of this multigenic family. 相似文献
137.
Although growth and productivity of most crops are significantly reduced by exposure to temperatures in excess of 35 °C, some plants thrive in geothermally heated soils characterized by chronic temperatures in excess of 40 °C. The morphological adaptations that enable these plants to colonize thermal environments are poorly understood. We characterized trichome development, silica accumulation, stomatal density, and waxy cuticle development in populations of Dichanthelium lanuginosum var sericeum (Schmoll) isolated from thermal and non-thermal environments to determine whether morphological changes existed in populations adapted to thermal environments. Plants isolated from thermal environments of Yellowstone National Park developed an extensive series of trichomes when exposed to chronic temperatures of 45/35 °C (day/night). In contrast, isolates from non-thermal environments of western Oregon showed minimal trichome development during exposure to the elevated temperatures. Leaves that developed during exposure to elevated temperatures had reduced thickness, though the reduction was less marked in plants from populations isolated from thermal environments. Plants isolated from thermal environments also had greater numbers of stomata on adaxial leaf surfaces relative to biotypes isolated from non-thermal environments. These results suggest phenotypic characteristics that may be useful in selection of new varieties of crop species with improved tolerance to supraoptimal temperatures. 相似文献
138.
Comparative plant successional studies on derelict sites are providing significant insights into vegetation dynamics to ensure the success of future revegetation projects in these areas and, in the short-term, by using a space-for-time substitution. In this paper we describe, in relation to site exposure, vegetation development on waste rock materials covered with biologically active soil media, and compare this development with that from a previous study at the same mine (CW Spain) on non-biologically modified waste rock materials. The succession under study is faster on the North slope, as expected, and does not differ significantly from the general pattern of primary revegetation, although it was characterised by its own sequence of plant species. The topsoiling of waste increases richness and diversity from the first year of revegetation, reduces the time required for recovery of a terminal stage, and highlights the influence of slope orientation on vegetation dynamics. A total of 237 plant taxa were recorded, showing one of four patterns of change: (1) ‘pioneer’, (2) ‘intermediate’, (3) ‘late coloniser’ and (4) ‘fluctuating’. 相似文献
139.
Smart & Scott (2004, this is sue) criticized our paper (Wamelink et al. 2002) about the bias in average Ellenberg indicator values. Their main criticism concerns the method we used, regression analysis. They state the bias can be mimicked by the construction of an artificial data set and that regression analysis is not a suited tool to investigate underlying phenomena. Moreover they claim that the present bias is caused by the distribution of Ellenberg indicator values between syntaxa, instead of a bias in average Ellenberg indicator values per species. We show that their criticism of the use of regression analysis does not hold. We selected average Ellenberg values per vegetation group for several pH classes and applied an F‐test to determine whether or not the vegetation groups within each pH class differed significantly from each other. This was the case for all tested classes (P < 0.001). Moreover we simulated an artificial data set, of which the F‐test for varying measurement error could not explain the magnitude of the F‐value we found earlier. This indicates that the bias we found in average Ellenberg indicator values cannot be explained by measurement errors or by regression to the mean. In the end, Smart & Scott, as we did, come to the conclusion that there is a bias present and that separate regression lines per vegetation type are necessary, but the debate remains open on whether or not this is caused by the bias in Ellenberg indicator values per species. 相似文献
140.
ZiMian Wang Stanley Heshka Kuan Zhang Carol N. Boozer Steven B. Heymsfield 《Obesity (Silver Spring, Md.)》2001,9(5):331-336
There are many published methods for predicting resting energy expenditure (REE) from measured body composition. Although these published reports extend back almost a century, new related studies appear on a regular basis. It remains unclear what the similarities and differences are among these various methods and what, if any, advantages the newly introduced REE prediction models offer. These issues led us to develop an organizational system for REE prediction methods with the goal of clarifying prevailing ambiguities in the field. Our classification scheme is founded on body composition level (whole‐body, tissue‐organ, cellular, and molecular) and related components as the REE predictor variables. Each existing REE prediction method by body composition must belong to one body composition level. The suggested classification system, founded on a conceptual basis, highlights similarities and differences among the diverse REE‐body composition prediction methods, provides a framework for teaching REE‐body composition relationships, and identifies important future research opportunities. 相似文献