全文获取类型
收费全文 | 646篇 |
免费 | 12篇 |
国内免费 | 8篇 |
专业分类
化学 | 271篇 |
晶体学 | 13篇 |
力学 | 22篇 |
数学 | 160篇 |
物理学 | 200篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 22篇 |
2013年 | 38篇 |
2012年 | 39篇 |
2011年 | 39篇 |
2010年 | 23篇 |
2009年 | 30篇 |
2008年 | 35篇 |
2007年 | 34篇 |
2006年 | 30篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 20篇 |
2002年 | 15篇 |
2001年 | 22篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 7篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 7篇 |
1963年 | 4篇 |
排序方式: 共有666条查询结果,搜索用时 15 毫秒
51.
Popescu C. Voicu I. Alexandrescu R. Morjan I. Dumitras D. Popescu M. Fatu D. 《Journal of Thermal Analysis and Calorimetry》1999,56(1):183-189
This paper reports on the synthesis of various iron oxides by the IR laser processing of different iron salts. X-ray diffraction
techniques were used to characterize the reaction products. Some differences in terms of crystallite size and isotropy between
these oxides and those obtained from the same salt by thermal means are described and explained.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
52.
Claudio A. Téllez S. Sergio G. de la Riva Eduardo Hollauer Ionel Haiduc Cristian S. Silvestru 《光谱学快报》2013,46(7):1469-1483
Abstract The infrared and Raman spectra of dimethyldithiophosphinate anion (CH3)2PS2 were measured and the vibrational modes for the anion complex were assigned. A Normal Coordinate Analysis in the Modified General Valence Force Field (MGVFF) approximation was carried out assuming C2v symmetry. Ab Initio Calculations at RHF and MP2 level were also carried out for the anion geometry as well as for its frequencies, intensities and force constants. 相似文献
53.
Cristian D. Popescu 《Mathematische Nachrichten》2009,282(10):1370-1390
54.
An efficient and straightforward method for the preparation of spirodiazine derivatives is reported which involves mild reaction conditions and easily accessible reactants. A new class of spiroazaheterocycles, spiro[pyrrolidine-pyrrolo[3,4-c]pyrroles], is obtained. A feasible explanation is given for the unexpected results obtained at high energy (high temperatures, MW and ultrasound irradiation). 相似文献
55.
Dorin Popescu 《Journal of Algebra》2009,321(10):2782-2797
The Stanley's Conjecture on Cohen–Macaulay multigraded modules is studied especially in dimension 2. In codimension 2 similar results were obtained by Herzog, Soleyman-Jahan and Yassemi. As a consequence of our results Stanley's Conjecture holds in 5 variables. 相似文献
56.
Let be a prime. We show that the space of weight one Eisenstein series defines an embedding into ${\mathbb P}^{(p-3)/2}X_1(p)$ for the congruence group that is scheme-theoretically cut out by explicit quadratic equations.
Received: 8 November 2000 / Published online: 17 August 2001 相似文献
57.
We present Laplace field microscopy as a method for generating intrinsic contrast of transparent specimens. This technique uses a spatial light modulator to perform the Laplacian of the field in the Fourier plane of a microscope image. The resulting image incorporates phase information and thus renders high contrast images from phase objects. We demonstrate the potential of the method by imaging index-matched beads, unlabeled tissue slices, and dynamic live cells. 相似文献
58.
R. Cristescu C. PopescuA.C. Popescu S. GrigorescuI.N. Mihailescu A.A. CiucuS. Iordache A. AndronieI. Stamatin E. Fagadar-CosmaD.B. Chrisey 《Applied Surface Science》2011,257(12):5293-5297
We report the deposition by MAPLE of metallized nanostructured (5,10,15,20-tetraphenyl)porphinato manganese(III) chloride thin films onto gold screen-printed electrodes, or 〈1 1 1〉 Si substrates. The deposited nanostructures were characterized by atomic force microscopy and exhibited globular structures with average diameters decreasing with laser fluence. Raman spectroscopy showed that no major decomposition appeared. We have investigated the Mn(III)-metalloporphyrin thin films by cyclic voltammetry in order to evaluate the potential bio/chemosensing activity on dopamine neurotransmitter analyte. We have found that the manganese(III)-porphyrin is appropriate as a single mediator for dopamine sensing in the specific case of gold screen-printed electrodes. 相似文献
59.
In this paper we develop a theoretical model for the magnetically induced optical anisotropy in dense magnetic colloids made of spherical and un-aggregated magnetic monodomain nanoparticles. Both dipole-field and dipole-dipole magnetic and electric interactions between the magnetic monodomain particles are taken into account in the Hamiltonian of the system. Using the pair correlation function in a colloidal suspension of magnetic nanoparticles developed by Ivanov and Kuznetsova (2001) [11], the complex dielectric constant of a magnetic colloid is modeled as a function of the light polarization direction, the magnetic field intensity and magnetic particle concentration and diameter. The two main features of the model are that, on the one hand, it predicts the possibility of magnetically induced optical anisotropy in dense magnetic colloids made of spherical and un-aggregated monodomain nanoparticles, and on the other hand, unlike the existing models for diluted samples, it predicts a non-linear dependence of dichroism and birefringence on magnetic particle concentration. 相似文献
60.
Ovidiu Popescu 《Applied Mathematics Letters》2011,24(1):1-4
The aim of this paper is to extend a very recent result proved by Dori? (2009) [4], as well as other theorems given by Rhoades (2001) [2] and Dutta and Choudhury (2008) [3]. 相似文献