全文获取类型
收费全文 | 359篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
化学 | 280篇 |
晶体学 | 1篇 |
力学 | 9篇 |
数学 | 51篇 |
物理学 | 26篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 22篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 13篇 |
2012年 | 34篇 |
2011年 | 29篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 22篇 |
2007年 | 22篇 |
2006年 | 13篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 4篇 |
1973年 | 2篇 |
排序方式: 共有367条查询结果,搜索用时 10 毫秒
1.
The effects of the organometallic compounds Bu2Sn-D -(?;)sorbitol, Bu2Sn-D -(+)glucose, Bu2Sn-D -(?)fructose and Bu2Sn-D -(+)glyceraldehyde were tested in vivo on different stages of Ascidian development, larval movement and metamorphosis. Organotin(IV) complexes are organometallic compounds widely used as industrial biocides, antifouling agents and agricultural fungicides and are toxic to a range of organisms. Two-cell stage embryos, if incubated for one hour in the organotin (IV) solutions, stopped the cleavage, which was restored when they were transferred into normal sea water. The gastrula stage was seriously affected in 10?4mol dm?3 solutions of the above-mentioned complexes: 85% of the embryos were anomalous neurulae with open neural folds, 5% were twisted larvae. The gastrulae, when incubated for 1 h in 10?5mol dm?3 solutions, developed twisted larvae in ovular envelopes and immobile larvae with twisted tails. Larvae treated with 10?4mol dm?3 and 10?5 mol dm?3 Bu2Sn-D -(?)sorbitol, Bu2Sn-D -(+)glucose and Bu2Sn-D -(+)glyceraldehyde solutions stopped swimming, did not metamorphose and afterwards underwent cytolysis. An initial hyperactivity of circular movements, followed by immobility, was observed in the larvae incubated in Bu2Sn-D -(?;)fructose. 相似文献
2.
Roberto Cammi Caterina Ghio Jacopo Tomasi 《International journal of quantum chemistry》1986,29(3):527-539
The interaction of some neutral acids of π type, bearing appropriate unsymmetrical substitutions at the C?C group with some selected bases (H2O, NH3, OH?), is compared with that of the parent compound of a new set of neutral π acids, bearing symmetrical substitutions at the C?C group with the same bases. The analyses of the interaction energy, performed according to two decomposition schemes, with and without the counterpoise corrections, make clear the similarity of symmetrically and unsymmetrically substituted neutral organic acids. 相似文献
3.
Caterina Sartori 《manuscripta mathematica》1982,38(2):225-238
We present an asymptotic analysis for the solution of period 4 of
, where f is an odd function and a positive parameter.This work was supported by a C.N.R. fellowship during the period in which the author was visiting Rutgers University. 相似文献
4.
5.
Helen?BarbasEmail author Claus?C?Hilgetag Subhash?Saha Caterina?R?Dermon Joanna?L?Suski 《BMC neuroscience》2005,6(1):32
Background
The neocortical commissures have a fundamental role in functional integration across the cerebral hemispheres. We investigated whether commissural projections in prefrontal cortices are organized according to the same or different rules as those within the same hemisphere, by quantitatively comparing density, topography, and laminar origin of contralateral and ipsilateral projections, labeled after unilateral injection of retrograde tracers in prefrontal areas. 相似文献6.
We give both a topological and an algebraic definition of the order of a global branch of a variety along a subvariety. Then
we show that these two definitions agree. Finally we compare this order with the orders of the related local branches.
Partially supported by CNR funds. 相似文献
Sunto Diamo due definizioni, una topologica e una algebrica, di ordine di un ramo globale di una varietà lungo una sottovarietà. Poi mostriamo che queste due definizioni coincidono. Infine confrontiamo questo ordine con gli ordini dei relativi rami locali.
Partially supported by CNR funds. 相似文献
7.
Caterina Canovaro Irene Calliari Michele Asolati Francesco Grazzi Antonella Scherillo 《Applied Physics A: Materials Science & Processing》2013,112(4):1019-1025
Mixing of different organic charge-transfer-complexes (CT-complexes) might allow the adjustment of the optical and morphological properties of the resulting material system. In this work, a study of two CT-complexes, mixed by thermal coevaporation at different concentrations by substituting only the acceptor molecules, is presented. Electron diffraction patterns, which were collected on samples of the ternary system of the prototypical CT-complexes DBTTF-TCNQ and DBTTF-F4TCNQ do not show any indication of a mixed crystalline phase or novel crystalline order. X-ray diffraction measurements additionally confirm the phase separation in the ternary system. However, upon mixing of the complexes, the degree of crystallinity of the individual phases is reduced. This effect correlates with the mixing ratio of the CT-complexes in the ternary compound. Furthermore, we do not observe a shift or the appearance of new peaks in the infrared spectra of (DBTTF-TCNQ) x :(DBTTF-F4TCNQ)1?x . Hence, there is no indication for a pronounced or novel chemical interaction between the individual CT-complexes in the mixed compound. 相似文献
8.
Caterina Rinaudo Mario Allegrina Elisa Fornero Maya Musa Alessandro Croce Donata Bellis 《Journal of Raman spectroscopy : JRS》2010,41(1):27-32
Histological sections of a patient affected by an important respiratory disease were analysed firstly by optical microscope(OM)—crossed polarisers—to identify the presence of incorporated inorganic particles, with particular attention to the fibrous ones. Then, the particles/fibres that were found were studied both with micro‐Raman spectroscopy and variable‐pressure scanning electron microscopy with energy‐dispersive spectroscopy (VP‐SEM/EDS). The two techniques allowed the in situ characterisation of the inorganic phases without disintegration of the organic matter. Micro‐Raman spectroscopy was able to identify the vibrating chemical groups of the mineral phase associated with the inorganic grain while the crystalline structure was preserved by the biological system. The VP‐SEM/EDS characterisation, defining the elemental chemical composition of the analysed particle/fibre, allowed confirmation of the mineral phase deducible from spectroscopic data or its identification with certainty when the spectroscopic data were not exhaustive. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
9.
Villoresi P Bonora S Pascolini M Poletto L Tondello G Vozzi C Nisoli M Sansone G Stagira S De Silvestri S 《Optics letters》2004,29(2):207-209
We present a method for the optimization of high-order harmonic generation based on wave-front correction of the driving laser beam. The technique exploits wave-front adaptive control by means of a deformable mirror, governed by an optimization procedure. 相似文献
10.
Caterina Costa Carmela Cavalcante Francesca Zito Yukio Yokota Valeria Matranga 《Molecular diversity》2010,14(4):653-665
The extracellular matrix protein Pl-nectin, a 210-kDa homodimer originally purified from sea urchin eggs, plays a crucial role in cell adhesion and embryonic morphogenesis. The compiled cDNA sequence, obtained by RT-PCR primer walking and 3′ RACE, identified a 984aa product containing a 23aa signal peptide and including all six internal peptides identified by protein microsequencing. The protein is a new member of the galactose-binding protein superfamily as it consists of six 151–156aa-long tandemly repeated domains (D1–D6), homologous to the discoidin-like domains, also known as F5/8-type C domains. Based on homology modelling, we present a three-dimensional structure (3D) for D5, identified as the prototype domain. The molecular modelling of the assembled Pl-nectin homodimer accounts for a Pl-nectin quaternary structure composed of two 105-kDa C-shaped monomers linked by a S–S bridge. The presence of an LDT motif between the first and the second exposed loops of the D2 domain suggests the binding of Pl-nectin to an integrin receptor. Altogether, the in silico analysis described here is consistent with previous biochemical reports and offers a basis for predictions to be experimentally tested. 相似文献