全文获取类型
收费全文 | 259篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
化学 | 134篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 76篇 |
物理学 | 46篇 |
出版年
2022年 | 5篇 |
2021年 | 8篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 14篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 15篇 |
2004年 | 14篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1958年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有262条查询结果,搜索用时 15 毫秒
21.
Dr. Guanzhao Wu Yangxue Liu Hossein Rouh Liulei Ma Yao Tang Sai Zhang Peng Zhou Jia-Ying Wang Shengzhou Jin Dr. Daniel Unruh Dr. Kazimierz Surowiec Prof. Dr. Yanzhang Ma Prof. Dr. Guigen Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(30):8013-8020
The first asymmetric catalytic approach to multilayer 3D chirality has been achieved by using Suzuki-Miyaura cross-couplings. New chiral catalysts were designed and screened under various catalytic systems that proved chiral amide-phosphines to be more efficient ligands than other candidates. The multilayer 3D framework was unambiguously determined by X-ray structural analysis showing a parallel pattern of three layers consisting of top, middle and bottom aromatic rings. The X-ray structure of a catalyst complex, dichloride complex of Pd-phosphine amide, was obtained revealing an interesting asymmetric environment nearby the Pd metal center. Three rings of multilayer 3D products can be readily changed by varying aromatic ring-anchored starting materials. The resulting multilayer products displayed strong luminescence under UV irradiation and strong aggregation-induced emission (AIE). In the future, this work would benefit not only the field of asymmetric synthesis but also materials science, in particular polarized organic electronics, optoelectronics and photovoltaics. 相似文献
22.
A micro extraction – spectrophotometric procedure is developed for the determination of bismuth in pharmaceutical formulations.
The procedure is based on the extraction of tetraiodobismuthate(III) ion paired with benzyltributylammonium cation into chloroform.
The application of Nile Blue as internal standard (IS) enabled good analytical performance for micro-scale analysis. The ratio
between the absorbances measured at 491 nm (bismuth complex) and at 632 nm (IS) was taken as the analytical signal. The procedure
was carried out in Eppendorf tubes, lowering significantly the use of reagents and the volume of organic solvent. In the calibration
range up to 60 mgċl−1, the linear regression coefficient was 0.9999, the CV for 15 mgċl−1 and for 50 mgċl−1 Bi were 1.6% and 0.7% respectively. The results obtained in the analysis of pharmaceutical formulations were in good agreement
with the results of EDTA titration method.
Received November 25, 1999. Revision February 14, 2000. 相似文献
23.
24.
Tyihk Ern Mricz gnes M. Ott Pter G. Hajnos Michal L. Gowniak Kazimierz 《平面色谱法杂志一现代薄层色谱法》2008,21(5):331-336
JPC – Journal of Planar Chromatography – Modern TLC - The accumulation of hydrogen peroxide (H2O2) is an early and crucial step in paclitaxel-induced cancer cell death before commitment... 相似文献
25.
Marzena Ciemala Kazimierz Szymiczek 《Proceedings of the American Mathematical Society》2005,133(9):2519-2523
We prove that the kernel of the ring homomorphism between the Witt ring of any order of a global field and the Witt ring of the field is a nilideal.
26.
We prove an omega estimate related to the general Euler totient function associated to a polynomial Euler product satisfying some natural analytic properties. For convenience, we work with a set of L-functions similar to the Selberg class, but in principle our results can be proved in a still more general setup. In a recent paper the authors treated a special case of Dirichlet L-functions with real characters. Greater generality of the present paper invites new technical difficulties. Effectiveness of the main theorem is illustrated by corollaries concerning Euler totient functions associated to the shifted Riemann zeta function, shifted Dirichlet L-functions and shifted L-functions of modular forms. Results are either of the same quality as the best known estimates or are entirely new. 相似文献
27.
Bogdan Kaźmierczak Kazimierz Piechór 《Mathematical Methods in the Applied Sciences》2011,34(3):325-337
We study traveling wave solutions to a system of four non‐linear partial differential equations, which arise in a tissue interaction model for skin morphogenesis. Under the assumption that the strength of attachment of the epidermis to the basal lamina is sufficiently large, we prove the existence and uniqueness (up to a translation) of traveling wave solutions connecting two stationary states of the system with the dermis and epidermis cell densities being positive. We discuss the problem of the minimal wave speed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
28.
Kazimierz Szymiczek 《Semigroup Forum》2000,60(2):260-270
For semigroups with divisor theory we introduce an equivalence relation that preserves the p -dimensions of divisor class groups. While the approach has been motivated by the results on Hilbert-symbol equivalence in quadratic form theory over algebraic number fields, it is the purpose of the paper to generalize the setup to semigroups with divisor theory and to simplify the proofs by avoiding any ring- or number-theoretical arguments. 相似文献
29.
Zdzis?aw Dzedzej Kazimierz G?ba Wojciech Uss 《Journal of Fixed Point Theory and Applications》2011,10(2):233-252
A module structure of the cohomology Conley index is used to define a relative cup-length. This invariant is applied then to prove a multiplicity theorem for periodic solutions to Hamiltonian systems. 相似文献
30.