全文获取类型
收费全文 | 120篇 |
免费 | 5篇 |
专业分类
化学 | 82篇 |
力学 | 1篇 |
数学 | 8篇 |
物理学 | 34篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 2篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 1篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1987年 | 1篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有125条查询结果,搜索用时 15 毫秒
61.
62.
Gas‐Phase Interactions between Lead(II) Ions and Cytosine: Tandem Mass Spectrometry and Infrared Multiple‐Photon Dissociation Spectroscopy Study
下载免费PDF全文
![点击此处可从《Chemphyschem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Jean‐Yves Salpin Violette Haldys Dr. Sébastien Guillaumont Prof. Jeanine Tortajada Marcela Hurtado Prof. Al Mokhtar Lamsabhi 《Chemphyschem》2014,15(14):2959-2971
Gas‐phase interactions between Pb2+ ions and cytosine (C) were studied by combining tandem mass spectrometry, infrared multiple photon dissociation spectroscopy, and density functional theory (DFT) calculations. Both singly and doubly charged complexes were generated by electrospray. The [Pb(C)?H]+ complex was extensively studied, and this study shows that two structures, involving the interaction of the metal with the deprotonated canonical keto‐amino tautomer of cytosine, are generated in the gas phase; the prominent structure is the bidentate form involving both the N1 and O2 electronegative centers. The DFT study also points out a significant charge transfer from the nucleobase to the low‐lying p orbitals of the metal and a strong polarization of the base upon complexation. The various potential energy surfaces explored to account for the fragmentation observed are consistent with the high abundance of the [PbNH2]+ fragment ion. 相似文献
63.
Robert Finsy Lue Deriemaeker Nicolas De Jaeger Rik Sneyers Jan Vanderdeelen Paul Van der Meeren Hugo Demeyere Jeanine Stone-Masui Anne Haestier Julius Clauwaert Walter De Wispelaere Pascal Gillioen Sabine Steyfkens Erik Gelad 《Particle & Particle Systems Characterization》1993,10(3):118-128
The practical performances of single and multi-angle photon correlation spectroscopy (PCS) for resolving bimodal distributions of industrial poly (methyl methacrylate) samples was investigated in a comparative study by several users affiliated to academic and industrial groups and by two suppliers of commercial equipment. The results for the harmonic intensity averaged diameters obtained by cumulants analysis reported by the different laboratories are in agreement, in addition to the results for the normalized second cumulants. The uncertainty on the latter quantities is large, however. For the bimodal samples with two populations with average diameters in a ratio of about 2.5 : 1, not all users were able to resolve the distribution in its components by single-angle PCS. Some slight improvement was obtained by multi-angle PCS. Other indirect techniques (polarization intensity differential scattering, static light scattering data and disc photosedimentometer) appeared to be superior for resolving the bimodal distributions. 相似文献
64.
The magnetic microstructure and domain wall distribution of antiferromagnetic α-Fe2O3 epitaxial layers is determined by statistical image analyses. Using dichroic spectromicroscopy images, we demonstrate that the domain structure is statistically invariant with thickness and that the antiferromagnetic domain structure of the thin films is inherited from the ferrimagnetic precursor layer one, even after complete transformation into antiferromagnetic α-Fe2O3. We show that modifying the magnetic domain structure of the precursor layer is a genuine way to tune the magnetic domain structure and domain walls of the antiferromagnetic layers. 相似文献
65.
The paper reports on a detailed study of the N2–H2 collisional line broadening coefficient. High resolution stimulated Raman spectra of nitrogen–hydrogen mixtures have been recorded at liquid nitrogen and room temperatures. Corresponding linewidth calculations have been performed at temperatures between 77 and 500?K using the semiclassical Robert and Bonamy model for J rotational quantum numbers varying between 0 and 11. Comparison between experimental data and calculated results shows good agreement at room temperature using an adjusted value for the kinetic diameter. 相似文献
66.
The self-affine properties of postmortem fracture surfaces in silica glass and aluminum alloy were investigated through the 2D height-height correlation function. They are observed to exhibit anisotropy. The roughness, dynamic, and growth exponents are determined and shown to be the same for the two materials, irrespective of the crack velocity. These exponents are conjectured to be universal. 相似文献
67.
M. Afzelius P.-E. Bengtsson J. Bood J. Bonamy F. Chaussard H. Berger T. Dreier 《Applied physics. B, Lasers and optics》2002,75(6-7):771-778
Rotational coherent anti-Stokes Raman spectroscopy (CARS) is a well-established spectroscopic technique for thermometry at
pre-combustion temperatures and atmospheric pressure. However, at pressures of several MPa, a previous investigation revealed
large discrepancies between experimental data and the theoretical model. A re-evaluation has been made of these data (at room
temperature and in the range 1.5–9 MPa) with two improvements to the spectral code. The first is the inclusion of an inter-branch
interference effect, which is described in detail in Paper I. The second is the use of experimental S1-branch Raman line widths measured at 295 K, with a temperature dependence extracted from semi-classical calculations following
the Robert–Bonamy formalism. It is shown that these two modifications significantly improve the theoretical model, since both
the spectral fits and the accuracy of the evaluated temperatures are considerably improved.
Received: 18 February 2002 / Revised version: 9 July 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +46-46/2224542, E-mail: mikael.afzelius@forbrf.lth.se 相似文献
68.
Hus JC Prompers JJ Brüschweiler R 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,157(1):119-123
In protein NMR the assignment of nuclear spin resonances is a prerequisite for all subsequent applications, such as studies of ligand binding, protein-DNA interactions, and dynamics. Resonance assignment is a time consuming step even when the 3D x-ray structure of the protein is available. A new strategy is presented to solve the "inverse" assignment problem, which is the determination of the NMR resonance assignment from a known 3D protein structure. The protocol employs NMR data in the form of residual dipolar couplings and chemical shifts, while it does not require any sequential NMR connectivity information. The assignment problem is mathematically formulated in terms of a weighted matching problem that can be computationally efficiently solved by a combinatorial optimization algorithm. The protocol is applied to ubiquitin using two or three residual dipolar couplings per amino acid measured in Pfl phage medium together with chemical shift information. The algorithm yields for more than 90% of the protein backbone resonances the correct assignment. 相似文献
69.
Nicole Rolland Georges Vass Jeanine Cleophax Anne-Marie Sepulchre Stephan D. Gero Andr Cier 《Helvetica chimica acta》1982,65(5):1627-1636
Total synthesis of α-disaccharidyl-2,5,6-trideoxy-streptamines related to aminoglycoside antibiotics derived from maltose and lactose The synthesis of the hitherto unknown 4-O-substituted α-linked pseudo-tri-saccharides 1,2 and 3 is described. The key intermediates required in the reaction sequence are the glycals 12, 13 and 14 , prepared from maltose, lactose and the chiral ditosyloxy-cyclohexanol 15 , readily accessible from quinic acid. The pivotal step in the reaction's scheme - a stereospecific α-glycosylution procedure -, is an acid-catalyzed addition of the alcohol 15 to the glycals 12, 13 and 14 leading to the corresponding 2,3-unsaturated trisaccharides. The latter compounds were transformed to the target α-glycosides of 2,5,6-trideoxystreptamine 1, 2 and 3 which were devoid of significant antibacterial activity. These results indicate that the presence of an ether linkage at the position 4′ is probably critical for antibacterial activity. 相似文献
70.
Shear waves generated from an ultrasonic transducer are used to twist dynamically growing crack fronts; the response of crack front to such external perturbations is examined in order to investigate the primary cause of surface roughening in brittle materials. The response of the crack front is found to be linear in amplitude and frequency of the perturbing wave and without persistence. The response to random perturbations, e.g., by localized material inhomogeneities at the free surface, is also discussed. 相似文献