全文获取类型
收费全文 | 915篇 |
免费 | 43篇 |
国内免费 | 7篇 |
专业分类
化学 | 521篇 |
晶体学 | 5篇 |
力学 | 36篇 |
数学 | 251篇 |
物理学 | 152篇 |
出版年
2023年 | 12篇 |
2022年 | 20篇 |
2021年 | 30篇 |
2020年 | 28篇 |
2019年 | 21篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 54篇 |
2015年 | 39篇 |
2014年 | 48篇 |
2013年 | 75篇 |
2012年 | 84篇 |
2011年 | 57篇 |
2010年 | 33篇 |
2009年 | 31篇 |
2008年 | 50篇 |
2007年 | 41篇 |
2006年 | 40篇 |
2005年 | 20篇 |
2004年 | 32篇 |
2003年 | 35篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1969年 | 2篇 |
1924年 | 2篇 |
1911年 | 2篇 |
1897年 | 2篇 |
1893年 | 2篇 |
排序方式: 共有965条查询结果,搜索用时 15 毫秒
61.
Nicoleta Petrea Răzvan Petre Andrada Pretorian Constantin Toader Vasile Şomoghi Florentina Neaţu Mihaela Florea Ştefan Neaţu 《Comptes Rendus Chimie》2018,21(3-4):339-345
The catalytic methanolysis of the chemical warfare nerve agents soman, sarin, and VX was investigated by using Cu or Zn complexes. Although VX withstood decontamination, the decomposition yield being around 96%, the soman and sarin deposited on different surfaces were almost fully destroyed under ambient conditions. The catalytic tests performed on a wide range of contaminated surfaces confirm the activity of the investigated catalytic systems, these complexes being suitable, from an economical point of view, for use in the formulation of a possible decomposition kit with military or civilian applicability. 相似文献
62.
Gabriela Ionita Petre Ionita Victor EM. Sahini Constantin Luca 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(3-4):269-271
The kinetics of oxidation of amino acids (Arg, His, Lys, Phe, Thr and Tyr), a dipeptide (Gly-His), and BSA (bovine serum albumin) by two persistent water soluble free radicals of the hydrazyl type has been studied.The rate decreases in the order Arg>Lys>Tyr>Thr>HisBSAPheGly-His with bothfree radicals. Addition to the reaction mixture of - and -cyclodextrin decreases the oxidation rate, probably due to amino acidencapsulation in the cyclodextrin cavity. -Cyclodextrin protects more efficiently against oxidation than -cyclodextrin. 相似文献
63.
Constantin Schwecke Walter Kaminsky 《Journal of polymer science. Part A, Polymer chemistry》2001,39(16):2805-2812
Benzyl cyclopentadienyl titanium trichloride (BzCpTiCl3) was synthesized from benzyl bromide, cyclopentadienyl lithium, and titanium tetrachloride and used in combination with methylaluminoxane (MAO) for the syndiospecific polymerization of styrene. Kinetic measurements of the polymerization were carried out at different temperatures. The polymerization with BzCpTiCl3/MAO differs from the polymerization with cyclopentadienyl titanium trichloride in its behavior toward the Al/Ti ratio. In addition, high activities are observed at high Al/Ti ratios. By analyzing the polymerization runs and the physical properties of the polymers with differential scanning calorimetry, 13C NMR spectroscopy, wide‐angle X‐ray scattering measurements, and gel permeation chromatography, we found that the phenyl ring coordinates to the titanium atom during polymerization. Other known substitutions of the cyclopentadienyl ring (V. Scholz, Dissertation, University of Hamburg, 1998) in principle influence the polymerization activity. The physical properties of the polymers produced by the catalysts already known are nearly identical. BzCpTiCl3 is the first catalyst that leads to polystyrene obviously different from the polystyrene produced by other highly active catalysts. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2805–2812, 2001 相似文献
64.
65.
66.
Aurelian Luca Maria Sahagia Andrei Antohe Mihail-Răzvan Ioan Leonardo Şerbina Constantin Ivan 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(2):1075-1079
In order to validate its original method for the radon gas activity standardization and to assure the international metrological traceability and equivalence, the Radionuclide Metrology Laboratory of IFIN-HH participated recently in the international comparison CCRI(II)-K2.Rn-222, organized by the International Committee for Weights and Measures—CIPM-CCRI(II)-Radionuclide Measurements. The radon gas sample received, the measurement equipment and the experimental procedures are described. Because the comparison is underway, the results are presented only as relative values to the liquid scintillator vial measurement result. The uncertainty budget of the measurements performed is provided. 相似文献
67.
68.
One proves that any rank 3 topological vector bundle on a homogeneous rational 3-fold has an algebraic structure. The proof uses extensions of ideals by rank 2 vector bundles. The paper also contains a construction of rank 3 vector bundles on 3-folds using extensions of ideals by rank 2 reflexive sheaves. 相似文献
69.
Constantin Tudor 《Applied Mathematics and Optimization》1989,20(1):319-331
Existence, uniqueness, continuous dependence with respect to controls and convergence in the probability of finite differences for controlled semilinear stochastic evolution equations, driven by continuous semimartingales, are considered under Lipschitz and monotone coefficients. The existence of discrete-optimal feedback controls for an associated optimization problem is proved. 相似文献
70.
Constantin Costara 《Archiv der Mathematik》2015,105(2):153-162
Let x 0 be a nonzero vector in \({\mathbb{C}^{n}}\) , and let \({U\subseteq \mathcal{M}_{n}}\) be a domain containing the zero matrix. We prove that if φ is a holomorphic map from U into \({\mathcal{M}_{n}}\) such that the local spectrum of T ∈ U at x 0 and the local spectrum of φ(T) at x 0 have always a common value, then T and φ(T) have always the same spectrum, and they have the same local spectrum at x 0 a.e. with respect to the Lebesgue measure on U. If \({\varphi \colon U\rightarrow \mathcal{M}_{n}}\) is holomorphic with φ(0) = 0 such that the local spectral radius of T at x 0 equals the local spectral radius of φ(T) at x 0 for all T ∈ U, there exists \({\xi \in \mathbb{C}}\) of modulus one such that ξT and φ(T) have the same spectrum for all T in U. We also prove that if for all T ∈ U the local spectral radius of φ(T) coincides with the local spectral radius of T at each vector x, there exists \({\xi \in \mathbb{C}}\) of modulus one such that φ(T) = ξT on U. 相似文献