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排序方式: 共有428条查询结果,搜索用时 15 毫秒
421.
Tatiana Prikhna Wolfgang Gawalek Yaroslav Savchuk Vasiliy Tkach Nikolay Danilenko Michael Wendt Jan Dellith Harold Weber Michael Eisterer Viktor Moshchil Nina Sergienko Artem Kozyrev Peter Nagorny Andrey Shapovalov Vladimir Melnikov Sergey Dub Doris Litzkendorf Tobias Habisreuther Christa Schmidt Athanasios Mamalis Vladimir Sokolovsky Vladimir Sverdun Fridrich Karau Alexandra Starostina 《Physica C: Superconductivity and its Applications》2010,470(19):935-938
The study of high pressure (2 GPa) synthesized MgB2-based materials allows us to conclude that higher borides (with near MgB12 stoichiometry) and oxygen-enriched Mg–B–O inclusions can be pinning centers in nanostructural magnesium diboride matrix (with average grain sizes of 15–37 nm). It has been established that additions of Ti or SiC as well as manufacturing temperature can affect the size, amount and distribution of these inclusions in the material structure and thus, influence critical current density. The superconducting behavior of materials with near MgB12 stoichiometry of matrix is discussed. 相似文献
422.
Uta Breuer Yaroslav Terentiev Gotthard Kunze Wolfgang Babel 《Macromolecular bioscience》2002,2(8):380-386
The genes of the poly(β-hydroxybutyrate) (PHB) synthesis pathway in Ralstonia eutropha and Methylobacterium extorquens were successfully established in the yeast Saccharomyces cerevisiae. Expression of just the polyhydroxyalkanoate (PHA) synthase gene in some experiments, and all three PHB genes (i.e., the genes encoding β-ketothiolase, acetoacetyl-CoA reductase, and PHA synthase) in others, were detected in S. cerevisiae. Thus, it can be used as a “cell factory” for the production of PHB. The maximum amount of polyester accumulated was 6.7% (wt./wt.) when all three genes were expressed. The amount of polymer accumulated in the transgenic yeast harboring just the PHA synthase gene was similar (5.2%), but slightly lower, indicating the necessity of expressing all three genes for high PHB contents in the cells. For viable production of the polymer in yeasts, more needs to be learned about the metabolism of the yeast, especially about the pathways and intermediates competing with formation of the biopolymer. Another host probably needs to be chosen.
423.
Arkady D. Litmanovich Yaroslav V. Kudryavtsev Yury A. Kriksin Oleg A. Kononenko 《Macromolecular theory and simulations》2003,12(1):11-16
A new approach is suggested to estimate the theoretical maximum capability to order for stretched Bernoullian copolymers AB, provided interchain AB contacts are unfavorable. A simple Monte Carlo procedure simulating the ordering of such copolymers via rotation of ring‐shaped chains reveals the capability to order even for quite long copolymer chains. The analytical probabilistic consideration is elaborated, which enables one to interpret the ordering via rotation in terms of a sliding of periodic Bernoullian chains. Using both the probabilistic analysis and Monte Carlo simulations it is shown that estimations of a capability to order given by the rotation procedure are also good for a sliding of true Bernoullian copolymers. Therefore, the simple Monte Carlo procedure seems suitable for estimating ordering in other classes of copolymers for which an analytical approach is more complicated. Such estimations might be useful for a consideration of various properties of irregular copolymers connected with their tendency to order.
424.
Nicolai Plat Arkady Litmanovich Victor Yashin Yaroslav Kudryavtsev Elena Govorun 《Macromolecular Symposia》1997,118(1):347-362
The main task of the theory of macromolecular reactions in polymer blends is to describe an evolution of the blend structure under the concerted action of the reaction and interdiffusion. For a polymeranalogous reaction proceeding with autoacceleration in a compatible blend, the task has been solved by methods of linear non-equilibrium thermodynamics. The set of reaction-diffusion equations derived permits to describe the blend structure in details, including the parameters characterizing compositional heterogeneity and units' distribution of the reacting chains in any local region of the blend. For incompatible blend of two homopolymers, the competition between a phase separation and the reaction of end-coupling with a formation of diblock-copolymer has been considered. The peculiarities of the processes mentioned as well as the actual problems in this field are discussed. 相似文献
425.
Yaroslav V. Galadzhun Vasyl' I. Zaremba Yaroslav M. Kalychak Rolf‐Dieter Hoffmann Rainer Poettgen 《ChemInform》2000,31(48):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
426.
Danylo I. Kravchuk Ganna V. Sotkis Mykola M. Shcherbatiuk Ruslan M. Kravchuk Vassili G. Nazarenko Petro P. Gorbyk Yaroslav M. Shuba 《Photochemistry and photobiology》2023,99(1):78-82
Caged compounds comprise the group of artificially synthesized, light-sensitive molecules that enable in situ derivation of biologically active constituents capable of affecting cells, tissues and/or biological processes upon exposure to light. Ruthenium-bispyridine (RuBi) complexes are photolyzed by biologically harmless visible light. In the present study, we show that RuBi-caged nicotine can be used as a source of free nicotine to induce proliferation of A549 nonsmall-cell lung cancer (NSCLC) cells by acting on nicotinic acetylcholine receptors expressed in these cells. RuBi-nicotine was photolyzed using LED light source with the spectrum matching RuBi-absorption. Photorelease of free nicotine ([Nic]p/r) was quantified by high-performance liquid chromatography (HPLC). 5-s-long light exposure of 10 μm of RuBi-nicotine generated 2 μm [Nic]p/r which enhanced A549 cell proliferation similarly to the 2 μm of plain nicotine during 72 h of cell culturing. Both RuBi-nicotine per se and its photolysis byproduct exerted no effect on A549 cells. We conclude that RuBi-nicotine can be a good source of free nicotine for inducing short- and long-term biological effects. Photolysis of RuBi-nicotine is quite effective, and can produce biologically relevant concentrations of nicotine at acceptable concentrations of the source material with the use of simple, inexpensive, and easily accessible light sources. 相似文献
427.
Nikolay A. Platé Arkady D. Litmanovich Yaroslav V. Kudryavtsev Elena N. Govorun 《Macromolecular Symposia》2003,191(1):11-20
Various effects produced by copolymers in polymer blends are discussed, with an emphasis on the role of interchain interactions. Simple theoretical models are considered to study the following problems: the interplay of diffusion and macromolecular reaction in compatible and incompatible blends, the stabilizing effect of premade diblock copolymer on the system of minor phase particles in incompatible blends, the kinetics of transesterification in a homogeneous blend. The effect of diblock copolymer on the Ostwald ripening in a polymer blend is stated in more details; the possibility of narrowing the size distribution of minor phase particles is predicted. 相似文献
428.
Bogdan V. Semak Dr. Yaroslav M. Beltukov Prof. Oleg S. Vasyutinskii 《Chemphyschem》2023,24(22):e202300405
Dichroism and birefringence in Stimulated Raman Scattering (SRS) in polyatomic molecules were studied theoretically. General expressions describing the change of the polarization matrix of the probe laser beam transmitted through initially isotropic molecular sample excited by the pump laser beam have been derived. Arbitrary polarization states and propagation directions of the incoming pump and probe beams were considered. The expressions were written in terms of spherical tensor operators that allowed for separation of the field polarization tensor and the molecular part containing three scalar values of nonlinear optical susceptibility with =0,1,2. The geometry of almost collinear propagation of the pump and probe beams through the molecular sample was considered in greater details. It was shown that the dichroism and birefringence refer to the nonlinear optical susceptibility element and that their contributions to the SRS signal can be separated experimentally by using an appropriate probe beam polarization analyzer installed in front of the photodetector. Particular cases of the off-resonant SRS and resonant SRS have been considered. The results obtained were expressed in terms of the Stokes polarization parameters of the pump and probe beams. 相似文献