全文获取类型
收费全文 | 310篇 |
免费 | 6篇 |
国内免费 | 5篇 |
专业分类
化学 | 120篇 |
晶体学 | 9篇 |
力学 | 14篇 |
数学 | 28篇 |
物理学 | 150篇 |
出版年
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 6篇 |
2012年 | 12篇 |
2011年 | 9篇 |
2010年 | 2篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 29篇 |
2006年 | 30篇 |
2005年 | 33篇 |
2004年 | 19篇 |
2003年 | 10篇 |
2002年 | 11篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1960年 | 2篇 |
1954年 | 2篇 |
1923年 | 4篇 |
1922年 | 5篇 |
1920年 | 1篇 |
1910年 | 1篇 |
排序方式: 共有321条查询结果,搜索用时 15 毫秒
1.
Z. A. Samoilenko V. D. Okunev E. I. Pushenko T. A. D’yachenko A. Cherenkov P. Gierlowski S. J. Lewandowski A. Abal’oshev A. Klimov A. Szewczyk 《Technical Physics》2003,48(2):250-256
Crystallographic phase transitions in perovskite-like LaSrMnO metallic oxides are studied. The transitions are induced when
internal stresses generated during film synthesis (at temperatures between 450 and 730°C) vary (decrease or increase) upon
subsequent irradiation by a KrF laser emitting in the UV range. As the synthesis temperature T
s grows, the rhombohedral-to-orthorhombic phase transition occurs at 650–670°C. The resistivity is shown to be either temperature-independent,
ρ(T)=const, at T<T
crit, or varies and reaches a maximum, ρ(T)=ρmax, at the Curie temperature T
c. Optical transmission spectra taken at photon energies ℏω=0.5–2.5 eV exhibit both a high (0.8–0.9) and low (0.1–0.3) transmission
coefficient t, depending on the synthesis temperature. As follows from X-ray diffraction data, the laser irradiation causes a phase transition
only in LaSrMnO films grown at T
s<650°C. Phases of different size scales appear: the long-range-order orthorhombic matrix and mesoscopic-range-order rhombohedral
clusters are observed in the films grown at T
s=450–550°C and the rhombohedral matrix with orthorhombic clusters, in the films grown at T
s=550–650°C. 相似文献
2.
A new method for the solution of the damped Burgers' equation is described. The marker method relies on the definition of a convective field associated with the underlying partial differential equation; the information about the approximate solution is associated with the response of an ensemble of markers to this convective field. Some key aspects of the method, such as the selection of the shape function and the initial loading, are discussed in some details. The marker method is applicable to a general class of nonlinear dispersive partial differential equations. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 相似文献
3.
4.
A. Hulanicki R. Lewandowski A. Lewenstam M. Chmurska H. Matuszak 《Mikrochimica acta》1985,87(3-4):253-264
Summary
The Study of Titration Conditions in the Aluminium and Beryllium-Fluoride Systems
The conditions for the titrimetric determination of aluminium and beryllium using fluoride as a titrant and a fluoride indicator electrode have been determined. 10g ml–1 Al and 3g ml–1 Be have been determined with precision better than 0.4%. The formation of slightly soluble sodium hexafluoroaluminate or tetrafluoroberyllate is primarily responsible for the end point breaks. The study of the reaction conditions (ethanol, sodium and acetate ions concentration) made the calculation of stepwise stability constants for aluminium- or beryllium-fluoride complexes, aluminium- or beryllium-acetate complexes as well as that of the solubility products of the corresponding sodium salts possible. 相似文献
5.
W. Lewandowski W. Priebe P. Koczon P. Moscibroda A. Orzechowska 《Analytical and bioanalytical chemistry》1996,355(5-6):750-752
The influence of halogens and metals on the electronic system of the aromatic ring in lithium, sodium and potassium complexes with p-halogenobenzoic acids has been investigated by means of 13C and 1H NMR, IR and Raman spectroscopy and semi-empirical calculations. It has been shown that ionic potentials and electronegativities of halogens and metals are the main factors responsible for perturbations of the electronic charge distribution in the ring. 相似文献
6.
OEP(八乙基卟啉阴离子)和TPP(四苯基卟啉阴离子)合钌(Ⅱ)和锇(Ⅱ)的二氧加合物由matrix分离技术得到(T=20-43K,P=10-5-10-6torr).为了确定v(O2)带的归属应用了同位素取代法16O2/18O2.IR谱说明对于钌的两种加合物(指OEP和TPP)都有两种异构体,其V(16O2)频率为:Ru(OEP)O2,1141和1103cm-1;Ru(TPP)O2,1167和1114cm-1.Os(TPP)O2只生成一种异构体,v(16O2)=1090cm-1,异构体v(16O2):[Ru(OEP)O2],1141cm-1,[Ru(TPP)O2],1167cm-1,这些加合物约在100K时分解,它们的结构指定为endon,而异构体[Ru(OEP)O2],1103cm-1,[Ru(TPP)O2],1114cm-1和[Os(TPP)O2],1090cm-1,在240—270K分解,它们的结构指定为桥联二聚体.在加合物中,将OEP换成TPP引起的钌加合物v(O2)频率的改变比铁和钴加合物更大.v(O2)相对强度的变化顺序为:Fe(Ⅱ)→Ru(Ⅱ)→Os(Ⅱ). 相似文献
7.
8.
Andrzej Lewandowski Lukasz Waligora Maciej Galinski 《Journal of solution chemistry》2013,42(2):251-262
The electrochemical behavior of cobaltocenium has been studied in a number of room temperature aprotic ionic liquids. Well defined, diffusion controlled, anodic and cathodic peaks were found for the Cc+/Cc (cobaltocenium/cobaltocene) reduction/oxidation on gold, platinum and glassy carbon electrodes. Values of the peak separation parameters suggest quasireversibility or even irreversibility for the redox process. The difference between the ferrocene/ferrocenium and cobaltocenium/cobaltocene couples has been evaluated as equal to (1.350 ± 0.020) V. Values of the cobaltocenium (Cc+) diffusion coefficients D have been calculated on the basis of the Randles–Sevcik equation. 相似文献
9.
Szymon Szufa Piotr Piersa ukasz Adrian Justyna Czerwiska Artur Lewandowski Wiktoria Lewandowska Jan Sielski Maria Dziku Marek Wrbel Marcin Jewiarz Adrian Knapczyk 《Molecules (Basel, Switzerland)》2021,26(4)
Miscanthus is resistant to dry, frosty winters in Poland and most European Union countries. Miscanthus gives higher yields compared to native species. Farmers can produce Miscanthus pellets after drying it for their own heating purposes. From the third year, the most efficient plant development begins, resulting in a yield of 25–30 tons of dry matter from an area of 1 hectare. Laboratory scale tests were carried out on the processes of drying, compacting, and torrefaction of this biomass type. The analysis of the drying process was conducted at three temperature levels of the drying agent (60, 100, and 140 °C). Compaction on a hydraulic press was carried out in the pressure range characteristic of a pressure agglomeration (130.8–457.8 MPa) at different moisture contents of the raw material (0.5% and 10%). The main interest in this part was to assess the influence of drying temperature, moisture content, and compaction pressure on the specific densities (DE) and the mechanical durability of the pellets (DU). In the next step, laboratory analyses of the torrefaction process were carried out, initially using the Thermogravimetric Analysis TGA and Differential Scaning Calorimeter DSC techniques (to assess activation energy (EA)), followed by a flow reactor operating at five temperature levels (225, 250, 275, 300, and 525 °C). A SEM analysis of Miscanthus after torrefaction processes at three different temperatures was performed. Both the parameters of biochar (proximate and ultimate analysis) and the quality of the torgas (volatile organic content (VOC)) were analyzed. The results show that both drying temperature and moisture level will affect the quality of the pellets. Analysis of the torrefaction process shows clearly that the optimum process temperature would be around 300–340 °C from a mass loss ratio and economical perspective. 相似文献
10.
Dr. Adrián Leandro Lewandowski Dr. Sergio Tosoni Leonard Gura Dr. Zechao Yang Dr. Alexander Fuhrich Dr. Mauricio J. Prieto Dr. Thomas Schmidt Dr. Denis Usvyat Prof. Wolf-Dieter Schneider Dr. Markus Heyde Prof. Gianfranco Pacchioni Prof. Hans-Joachim Freund 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(6):1870-1885
The present review reports on the preparation and atomic-scale characterization of the thinnest possible films of the glass-forming materials silica and germania. To this end state-of-the-art surface science techniques, in particular scanning probe microscopy, and density functional theory calculations have been employed. The investigated films range from monolayer to bilayer coverage where both, the crystalline and the amorphous films, contain characteristic XO4 (X=Si,Ge) building blocks. A side-by-side comparison of silica and germania monolayer, zigzag phase and bilayer films supported on Mo(112), Ru(0001), Pt(111), and Au(111) leads to a more general comprehension of the network structure of glass former materials. This allows us to understand the crucial role of the metal support for the pathway from crystalline to amorphous ultrathin film growth. 相似文献