全文获取类型
收费全文 | 395篇 |
免费 | 24篇 |
出版年
2022年 | 2篇 |
2021年 | 11篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 20篇 |
2012年 | 26篇 |
2011年 | 20篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 19篇 |
2007年 | 23篇 |
2006年 | 17篇 |
2005年 | 19篇 |
2004年 | 18篇 |
2003年 | 8篇 |
2002年 | 17篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 6篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有419条查询结果,搜索用时 15 毫秒
101.
102.
103.
Magazù S Migliardo F Benedetto A La Torre R Hennet L 《European biophysics journal : EBJ》2012,41(4):361-367
In this contribution the effects of the homologous disaccharides trehalose and sucrose on both water and hydrated lysozyme
dynamics are considered by determining the mean square displacement (MSD) from elastic incoherent neutron scattering (EINS)
experiments. The self-distribution function (SDF) procedure is applied to the data collected, by use of IN13 and IN10 spectrometers
(Institute Laue Langevin, France), on trehalose and sucrose aqueous mixtures (at a concentration corresponding to 19 water
molecules per disaccharide molecule), and on dry and hydrated (H2O and D2O) lysozyme also in the presence of the disaccharides. As a result, above the glass transition temperature of water, the MSD
of the water–trehalose system is lower than that of the water–sucrose system. This result suggests that the hydrogen-bond
network of the water–trehalose system is stronger than that of the water–sucrose system. Furthermore, by taking into account
instrumental resolution effects it was found that the system relaxation time of the water–trehalose system is longer than
that of the water–sucrose system, and the system relaxation time of the protein in a hydrated environment in the presence
of disaccharides increases sensitively. These results explain the higher bioprotectant effectiveness of trehalose. Finally,
the partial MSDs of sucrose/water and trehalose/water have been evaluated. It clearly emerges from the analysis that these
are almost equivalent in the low-Q domain (0–1.7 ?−1) but differ substantially in the high-Q range (1.7–4 ?−1). These findings reveal that the lower structural sensitivity of trehalose to thermal changes is connected with the local
spatial scale. 相似文献
104.
105.
106.
Fiorentino A D'Abrosca B Pacifico S Iacovino R Mastellone C Di Blasio B Monaco P 《Bioorganic & medicinal chemistry letters》2006,16(23):6096-6101
A novel antioxidant prenylated stilbenoid, distachyasin, has been isolated from the leaves of Carex distachya. Its structure has been elucidated on the basis of the spectroscopic characteristics. Bidimensional NMR, and crystallographic data and computational calculations have furnished important data useful for the characterization and the stereochemistry of the molecule. The compound has a tetracyclic skeleton derived from carexane. The compound has been assayed, for the antioxidant activity, by measuring its capacity to scavenge the H(2)O(2), nitric oxide, superoxide radical and to inhibit formation of TBARS (thiobarbituric acid reactive species). 相似文献
107.
Roberto Giorda M. Clara Bonaglia Silvana Beri Francesca Novara Jill Urquhart Claudio Zucca Susan Marelli Daniela Di Benedetto Girolamo A. Vitello Santina Reitano Francesca Bisulli Massimo Mastrangelo Luigina Spaccini Elena Fontana Jill Clayton-Smith Philippe Jonveaux Marco Seri Bernardo dalla Bernardina 《American journal of human genetics》2009,85(3):394-400
Submicroscopic copy-number variations make a considerable contribution to the genetic etiology of human disease. We have analyzed subjects with idiopathic mental retardation (MR) by using whole-genome oligonucleotide-based array comparative genomic hybridization (aCGH) and identified familial and de novo recurrent Xp11.22-p11.23 duplications in males and females with MR, speech delay, and a peculiar electroencephalographic (EEG) pattern in childhood. The size of the duplications ranges from 0.8–9.2 Mb. Most affected females show preferential activation of the duplicated X chromosome. Carriers of the smallest duplication show X-linked recessive inheritance. All other affected individuals present dominant expression and comparable clinical phenotypes irrespective of sex, duplication size, and X-inactivation pattern. The majority of the rearrangements are mediated by recombination between flanking complex segmental duplications. The identification of common clinical features, including the typical EEG pattern, predisposing genomic structure, and peculiar X-inactivation pattern, suggests that duplication of Xp11.22-p11.23 constitutes a previously undescribed syndrome. 相似文献
108.
Carolina L. Pometti Sabrina Palanti Benedetto Pizzo Jean-Paul Charpentier Nathalie Boizot Claudio Resio Beatriz O. Saidman 《Biodegradation》2010,21(5):753-760
The natural durability of four Argentinean species of Prosopis and one of Acacia was evaluated in laboratory tests, according to European standards, using three brown rot and one white rot fungi. These
tests were complemented by assessing the wood chemical composition. All the species were from moderately slightly durable
to very durable (classes 4–1), and in all cases the heartwood was the most resistant to fungal attack. Chemical extractives
content (organic, aqueous, tannic and phenolic) was higher in the heartwood. However, species durability was not related to
extractive contents nor with wood density. Instead, it is possible that extractives could contribute to natural durability
in different ways, including the effects related to the antioxidant properties of some of them. 相似文献
109.
Anna Chiara Maria Biressi Ting Zou Samuel Dupont Carl Dahlberg Cristiano Di Benedetto Francesco Bonasoro Michael Thorndyke Maria Daniela Candia Carnevali 《Zoomorphology》2010,129(1):1-19
All species of the Ophiuroidea have exceptional regenerative capabilities; in particular, they can replace arms lost following
traumatic or self-induced amputation. In order to reconstruct this complex phenomenon, we studied arm regeneration in two
different ophiuroids, Ophioderma longicaudum (Retzius, 1805) and Amphiura filiformis O. F. Müller, 1776, which are quite distantly related. These species present contrasting regeneration and differentiation
rates and differ in several ecological traits. The aim of this paper is to interpret the primary sequence of morphogenetic
and histogenetic events leading to the complete reconstruction of a new arm, comparing the arm regenerative processes of these
two ophiuroid species with those described in crinoids. Arm regeneration in ophiuroids is considered an epimorphic process
in which new structures develop from a typical blastema formed from an accumulation of presumptive undifferentiated cells.
Our results showed that although very different in some respects such as, for instance, the regeneration rate (0.17 mm/week
for O. longicaudum and 0.99 mm/week for A. filiformis), morphogenetic and histogenetic aspects are surprisingly similar in both species. The regenerative process presents similar
characteristics and follows a developmental scheme which can be subdivided into four phases: a repair phase, an early regenerative
phase, an intermediate regenerative phase and an advanced regenerative phase. In terms of histogenesis, the regenerative events
involve the development of new structures from migratory pluripotent cells, which proliferate actively, in addition in both
cases there is a significant contribution from dedifferentiated cells, in particular dedifferentiating myocytes, although
to varying extents. This evidence confirms the plasticity of the regenerative phenomenon in echinoderms, which can apparently
follow different pathways in terms of growth and morphogenesis, but nevertheless involve both epimorphic and morphallactic
contributions at the cellular level. 相似文献
110.