全文获取类型
收费全文 | 266篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
化学 | 156篇 |
力学 | 28篇 |
数学 | 47篇 |
物理学 | 40篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 15篇 |
2012年 | 23篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 9篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有271条查询结果,搜索用时 15 毫秒
41.
Cioffi C Campidelli S Brunetti FG Meneghetti M Prato M 《Chemical communications (Cambridge, England)》2006,(20):2129-2131
The functionalisation of single wall carbon nanohorns via 1,3-dipolar cycloaddition has been achieved, and the products have been characterised by spectroscopy, microscopy and thermogravimetry. 相似文献
42.
Riccò M Shiroka T Carretta S Bolzoni F Femoni C Iapalucci MC Longoni G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(9):2856-2861
The magnetic behaviour of the even-electron [Ni16Pd16(CO)40]4- cluster, in its [NnBu4]+ salt, has been investigated by magnetometry and muon spin rotation/relaxation (muSR) spectroscopy. The susceptibility measurements show an exceptionally high magnetic moment corresponding to a total spin value J=2. This suggests a Hund filling of a quadruplet ground state, quite unique in carbonyl-metal clusters. SQUID magnetometry shows a departure from the Curie-Weiss law, for T>150 K, and strong deviation from a Brillouin behaviour of the magnetisation curves. muSR spectroscopy in zero applied field shows a temperature independent decay of the muon spin polarisation, similar to that of a purely paramagnetic system. The observed muon spin repolarisation in a moderate external longitudinal field, however, invalidates this simple picture and suggests the presence of a local anisotropy field acting on the cluster's magnetic moment. A consistent interpretation of magnetometry and muSR results implies the occurrence of an additional interaction of the cluster spin with an effective crystalline field. The inclusion of this interaction in a model Hamiltonian allows us to successfully reproduce both the susceptibility and magnetisation data. 相似文献
43.
The dominant noises which limit the present sensitivity of the gravitational wave detectors are the thermal noise of the suspended
mirrors and the shot noise. For the third generation of gravitational wave detectors as the Einstein Telescope (ET), the reduction
of the shot noise implies to increase the power stored in the detector at 1 MW level and, at the same time, to compensate
the huge optic distortion due to induced thermal lensing. At low temperature it is possible to reduce both these effects.
However, lowering the temperature of the test masses without injecting vibration noise from the cooling system is a technological
challenge. We review here the thermal noise impact on the ultimate ET sensitivity limit and we discuss possible cryogenic
configurations to cool the mirror. 相似文献
44.
45.
Giovanni De Matteis Fulvio Bisi Epifanio G. Virga 《Continuum Mechanics and Thermodynamics》2007,19(1-2):1-23
We study the invariance properties of the molecular Hamiltonian interaction put forward by Straley to describe biaxial nematic phases. We show that the reduction to two out of four scalar order parameters, which was accidently remarked upon in the literature, is indeed a rigorous consequence of the Hamiltonian invariance for specific values of the interaction parameters. The stability analysis of the mean-field free energy in the reduction classes for the order parameters reveals a sequence of Landau triple points. 相似文献
46.
Four new jaspamide derivatives with antimicrofilament activity were isolated from the marine sponge Jaspis splendans. Their structures were elucidated by NMR and MS analysis. A structure-activity relationship analysis on all natural jaspamides is also reported here. 相似文献
47.
Eleonora Conca Mery Malandrino Aleandro Diana Ornella Abollino Agnese Giacomino Rafael Bartrolí Teresa Moreno Xavier Querol Fulvio Amato 《Molecules (Basel, Switzerland)》2022,27(21)
Aluminium is the most common substrate in studies using impactors for the measurement of the number or the weight of size-segregated atmospheric particulate matter (PM), as its characteristics perfectly fit impactor requirements. However, its use is not recommended by manufacturers when one of the purposes of the study is the determination of the metal content in the sample. The aim of this work was to develop an efficient analytical procedure for the removal and acid digestion of PM samples collected on aluminium foils by a cascade impactor to perform the determination of metals. The possibility of performing the trace metal analysis of PM samples collected using aluminium foils is of great importance, as it allows the determination of an accurate size distribution and the elemental composition of the PM collected on each impactor stage. Two procedures were optimised by using different digestion and analysis techniques. Both procedures were then applied to the two halves of several Dekati low-pressure impactor (DLPI) samples, and the results were critically compared. The two procedures proved to be effective in the determination of extremely low concentrations of a large suite of analytes in different size fractions of PM emitted by a brake system. 相似文献
48.
P. S. Ramanujam Christian Holme Sren Hvilsted Marianne Pedersen Fulvio Andruzzi Massimo Paci Eliana L. Tassi Pierluigi Magagnini Uwe Hoffman Ingo Zebger Heinz W. Siesler 《先进技术聚合物》1996,7(9):768-776
Azobenzene side-chain liquid crystalline polyester structures suitable for permanent optical storage are described. The synthesis and characterization of the polyesters together with differential scanning calorimetry and X-ray investigations are discussed. Optical anisotropic investigations and holographic storage in one particular polyester are described in detail and polarized Fourier transform infrared spectroscopic data complementing the optical data are presented. Optical and atomic force microscope investigations point to a laser-induced aggregation as responsible for permanent optical storage. 相似文献
49.
A local, complex, density and kinetic energy density-dependent effective force is derived from the G-matrix corresponding to two colliding nuclear matters. The Bethe-Goldstone equation uses the Reid soft-core interaction as input. The auxiliary single-particle potential is chosen self-consistently for all momenta. The results are presented in parametrized form. 相似文献
50.
R. Sartor 《Physics letters. [Part B]》1977,69(1):6-8
By taking due account of momentum conservation, it is shown that, when ω is near the Fermi energy ωF, the imaginary part of the mass operator for an infinite Fermi system behaves like (ω ? ωF)p(k) where the exponent p(k) ? 2 depends on the interval in which is lying. In particular, the commonly asserted quadratic behaviour (ω ? ωF2 is shown to be true only for . It is explicity assumed that the Fermi system admits a perturbative type treatment. 相似文献