全文获取类型
收费全文 | 1635篇 |
免费 | 84篇 |
国内免费 | 6篇 |
专业分类
化学 | 1008篇 |
晶体学 | 31篇 |
力学 | 28篇 |
数学 | 352篇 |
物理学 | 306篇 |
出版年
2023年 | 10篇 |
2022年 | 55篇 |
2021年 | 57篇 |
2020年 | 38篇 |
2019年 | 38篇 |
2018年 | 31篇 |
2017年 | 18篇 |
2016年 | 58篇 |
2015年 | 66篇 |
2014年 | 78篇 |
2013年 | 87篇 |
2012年 | 96篇 |
2011年 | 93篇 |
2010年 | 70篇 |
2009年 | 61篇 |
2008年 | 87篇 |
2007年 | 98篇 |
2006年 | 78篇 |
2005年 | 68篇 |
2004年 | 45篇 |
2003年 | 39篇 |
2002年 | 39篇 |
2001年 | 21篇 |
2000年 | 39篇 |
1999年 | 21篇 |
1998年 | 22篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 13篇 |
1993年 | 15篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 18篇 |
1985年 | 10篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1974年 | 5篇 |
1873年 | 6篇 |
排序方式: 共有1725条查询结果,搜索用时 31 毫秒
1.
Karolina Kula Agnieszka Kcka-Zych Agnieszka apczuk-Krygier Zbigniew Wzorek Anna K. Nowak Radomir Jasiski 《Molecules (Basel, Switzerland)》2021,26(5)
The present paper is a continuation of comprehensive study regarding to synthesis and properties of pyrazoles and their derivatives. In its framework an experimental and theoretical studies of thermal decomposition of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline were performed. It was found, that the decompositions of the mentioned pyrazoline system in the solution and at the melted state proceed via completely different molecular mechanisms. These mechanisms have been explained in the framework of the Molecular Electron Density Theory (MEDT) with the computational level of B3LYP/6-31G(d). A Bonding Evolution Theory (BET) examination of dehydrochlorination of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline permits elucidation of the molecular mechanism. It was found, that on the contrary for most known HCl extrusion processes in solution, this reaction is realised via single-step mechanism. 相似文献
2.
3.
Andrea Mühlbauer Stephan Seip Alexander Nowak VanSung Tran 《Helvetica chimica acta》2003,86(6):2065-2072
Chemical investigation of the roots of the Vietnamese plant Tacca paxiana resulted in the isolation of five new steroidal compounds, taccalonolide R ( 6 ), S ( 7 ), T ( 8 ), U ( 9 ), and V ( 10 ). Their structures were established on the basis of NMR and mass‐spectral data. In addition, the five known taccalonolides A ( 1 ), B ( 2 ), E ( 3 ), K ( 4 ), and N ( 5 ) were also isolated and identified. 相似文献
4.
Ivo Nezbeda 《Czechoslovak Journal of Physics》1998,48(1):117-122
By transforming a realistic water-water potential separately into long-ranged and short-ranged systems and using computer
simulations it is shown that the structure of water is determined primarily by short-ranged (both repulsive and attractive)
forces. An extended primitive model of water is then shown to provide both the spatial and orientational arrangement of water
molecules in the liquid phase in semi-quantitative agreement with diffraction experiments. Practical importance of this finding
is exemplified by formulating a perturbation expansion about the primitive model reference and its individual steps are analyzed
with respect to their implementation.
This work was supported by the Grant Agency of the Czech Republic (Grant No. 203/96/0585) and by the Grant Agency of the Academy
of Sciences of the Czech Republic (Grant No. A-4072607). 相似文献
5.
Florin Radu Alexei Nefedov Johannes GrabisGregor Nowak Andre BergmannHartmut Zabel 《Journal of magnetism and magnetic materials》2006
We have used soft X-ray resonant magnetic scattering (XRMS) to search for the presence of an effective ferromagnetic moment belonging to the antiferromagnetic (AF) layer which is in close contact with a ferromagnetic (F) layer. Taking advantage of the element specificity of the XRMS technique, we have measured hysteresis loops of both Fe and CoO layers of a CoO(40 Å)/Fe (150 Å) exchange bias bilayer. From these measurements we have concluded that the proximity of the F layer induces a magnetic moment in the AF layer. The F moment of the AF layer has two components: one is frozen and does not follow the applied magnetic field and the other one follows in phase the ferromagnetic magnetization of the F layer. The temperature dependence of the F components belonging to the AF layer is shown and discussed. 相似文献
6.
7.
Ohne Zusammenfassung 相似文献
8.
Piotr W. Nowak 《Journal of Functional Analysis》2007,243(1):323-344
We introduce a quasi-isometry invariant related to Property A and explore its connections to various other invariants of finitely generated groups. This allows to establish a direct relation between asymptotic dimension on one hand and isoperimetry and random walks on the other. We apply these results to reprove sharp estimates on isoperimetric profiles of some groups and to answer some questions in dimension theory. 相似文献
9.
The G/M/1 queue is one of the classical models of queueing theory. The goal of this paper is two-fold: (a) To introduce new derivations
of some well-known results, and (b) to present some new results for the G/M/1 queue and its variants. In particular, we pay attention to the G/M/1 queue with a set-up time at the start of each busy period, and the G/M/1 queue with exceptional first service.
Dedicated to Arie Hordijk on his 65th birthday, in friendship and admiration. 相似文献
10.
The optical properties—reflectivity, real part of the refractive index, absorption coefficient as well as the thermal and electrical conductivity of AlSi-alloy/SiCp composite were measured. The optical parameters and both conductivities decreased with the increase of SiCp particles volume in AlSi-alloy matrix. This decrease was almost linear for the volume fraction of SiCp particle up to 10 vol% of the total mass of the composite. For the 15 vol% of SiCp particles, the departure from linearity is connected with the presence of additional phases in AlSi-alloy/SiCp composite materials. The measured temperature dependencies of optical reflectivity and electrical conductivity for AlSi-alloy/SiCp 15 vol% are of metallic character. Modelling of the interaction of the CO2 laser radiation with AlSi-alloy/SiCp 15 vol% composite should allow to estimate the initiation time at which the surface composite reaches melting temperature. 相似文献