全文获取类型
收费全文 | 2949篇 |
免费 | 283篇 |
国内免费 | 1篇 |
专业分类
3233篇 |
出版年
2024年 | 2篇 |
2023年 | 32篇 |
2022年 | 51篇 |
2021年 | 116篇 |
2020年 | 66篇 |
2019年 | 79篇 |
2018年 | 91篇 |
2017年 | 84篇 |
2016年 | 128篇 |
2015年 | 169篇 |
2014年 | 192篇 |
2013年 | 240篇 |
2012年 | 319篇 |
2011年 | 290篇 |
2010年 | 140篇 |
2009年 | 130篇 |
2008年 | 178篇 |
2007年 | 174篇 |
2006年 | 149篇 |
2005年 | 117篇 |
2004年 | 101篇 |
2003年 | 95篇 |
2002年 | 87篇 |
2001年 | 32篇 |
2000年 | 25篇 |
1999年 | 17篇 |
1998年 | 17篇 |
1997年 | 16篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1979年 | 2篇 |
1975年 | 2篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1967年 | 2篇 |
1965年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有3233条查询结果,搜索用时 15 毫秒
151.
Paulo De Sa Peixoto Guillaume Laurent Thierry Aza?s Gervaise Mosser 《The Journal of biological chemistry》2013,288(11):7528-7535
In vivo, collagen I, the major structural protein in human body, is found assembled into fibrils. In the present work, we study a high concentrated collagen sample in its soluble, fibrillar, and denatured states using one and two dimensional {1H}-13C solid-state NMR spectroscopy. We interpret 13C chemical shift variations in terms of dihedral angle conformation changes. Our data show that fibrillogenesis increases the side chain and backbone structural complexity. Nevertheless, only three to five rotameric equilibria are found for each amino acid residue, indicating a relatively low structural heterogeneity of collagen upon fibrillogenesis. Using side chain statistical data, we calculate equilibrium constants for a great number of amino acid residues. Moreover, based on a 13C quantitative spectrum, we estimate the percentage of residues implicated in each equilibrium. Our data indicate that fibril formation greatly affects hydroxyproline and proline prolyl pucker ring conformation. Finally, we discuss the implication of these structural data and propose a model in which the attractive force of fibrillogenesis comes from a structural reorganization of 10 to 15% of the amino acids. These results allow us to further understand the self-assembling process and fibrillar structure of collagen. 相似文献
152.
Sylvie Tordjman George M. Anderson Michel Botbol Sylvie Brailly-Tabard Fernando Perez-Diaz Rozenn Graignic Michèle Carlier Gérard Schmit Anne-Catherine Rolland Olivier Bonnot Séverine Trabado Pierre Roubertoux Guillaume Bronsard 《PloS one》2009,4(8)
Background
Reports of reduced pain sensitivity in autism have prompted opioid theories of autism and have practical care ramifications. Our objective was to examine behavioral and physiological pain responses, plasma β-endorphin levels and their relationship in a large group of individuals with autism.Methodology/Principal Findings
The study was conducted on 73 children and adolescents with autism and 115 normal individuals matched for age, sex and pubertal stage. Behavioral pain reactivity of individuals with autism was assessed in three observational situations (parents at home, two caregivers at day-care, a nurse and child psychiatrist during blood drawing), and compared to controls during venepuncture. Plasma β-endorphin concentrations were measured by radioimmunoassay. A high proportion of individuals with autism displayed absent or reduced behavioral pain reactivity at home (68.6%), at day-care (34.2%) and during venepuncture (55.6%). Despite their high rate of absent behavioral pain reactivity during venepuncture (41.3 vs. 8.7% of controls, P<0.0001), individuals with autism displayed a significantly increased heart rate in response to venepuncture (P<0.05). Moreover, this response (Δ heart rate) was significantly greater than for controls (mean±SEM; 6.4±2.5 vs. 1.3±0.8 beats/min, P<0.05). Plasma β-endorphin levels were higher in the autistic group (P<0.001) and were positively associated with autism severity (P<0.001) and heart rate before or after venepuncture (P<0.05), but not with behavioral pain reactivity.Conclusions/Significance
The greater heart rate response to venepuncture and the elevated plasma β-endorphin found in individuals with autism reflect enhanced physiological and biological stress responses that are dissociated from observable emotional and behavioral reactions. The results suggest strongly that prior reports of reduced pain sensitivity in autism are related to a different mode of pain expression rather than to an insensitivity or endogenous analgesia, and do not support opioid theories of autism. Clinical care practice and hypotheses regarding underlying mechanisms need to assume that children with autism are sensitive to pain. 相似文献153.
154.
155.
156.
This report describes a new method allowing to measure the three-dimensional forces applied on right and left pedals during cycling. This method is based on a cycle ergometer mounted on a force platform. By recording the forces applied on the force platform and applying the fundamental mechanical equations, it was possible to calculate the instantaneous three-dimensional forces applied on pedals. It was validated by static and dynamic tests. The accuracy of the present system was -7.61 N, -3.37 N and -2.81 N, respectively, for the vertical, the horizontal and the lateral direction when applying a mono-directional force and -4.52 N when applying combined forces. In pedaling condition, the orientation and magnitude of the pedal forces were comparable to the literature. Moreover, this method did not modify the mechanical properties of the pedals and offered the possibility for pedal force measurement with materials often accessible in laboratories. Measurements obtained showed that this method has an interesting potential for biomechanical analyses in cycling. 相似文献
157.
Benjamin Bertin Yoan Renaud Rajaguru Aradhya Krzysztof Jagla Guillaume Junion 《Journal of visualized experiments : JoVE》2015,(103)
Measuring levels of mRNAs in the process of translation in individual cells provides information on the proteins involved in cellular functions at a given point in time. The protocol dubbed Translating Ribosome Affinity Purification (TRAP) is able to capture this mRNA translation process in a cell-type-specific manner. Based on the affinity purification of polysomes carrying a tagged ribosomal subunit, TRAP can be applied to translatome analyses in individual cells, making it possible to compare cell types during the course of developmental processes or to track disease development progress and the impact of potential therapies at molecular level. Here we report an optimized version of the TRAP protocol, called TRAP-rc (rare cells), dedicated to identifying engaged-in-translation RNAs from rare cell populations. TRAP-rc was validated using the Gal4/UAS targeting system in a restricted population of muscle cells in Drosophila embryos. This novel protocol allows the recovery of cell-type-specific RNA in sufficient quantities for global gene expression analytics such as microarrays or RNA-seq. The robustness of the protocol and the large collections of Gal4 drivers make TRAP-rc a highly versatile approach with potential applications in cell-specific genome-wide studies. 相似文献
158.
159.
160.
Using fish guilds to assess community responses to temperature and flow regimes in unregulated and regulated Canadian rivers 下载免费PDF全文
Camille J. Macnaughton Caroline Senay Ivan Dolinsek Guillaume Bourque Audrey Maheu Gabriel Lanthier Simonne Harvey‐Lavoie Joanie Asselin Pierre Legendre Daniel Boisclair 《Freshwater Biology》2016,61(10):1759-1772