全文获取类型
| 收费全文 | 755篇 |
| 免费 | 8篇 |
| 国内免费 | 4篇 |
专业分类
| 化学 | 454篇 |
| 晶体学 | 21篇 |
| 力学 | 10篇 |
| 数学 | 49篇 |
| 物理学 | 233篇 |
出版年
| 2024年 | 11篇 |
| 2023年 | 8篇 |
| 2022年 | 28篇 |
| 2021年 | 28篇 |
| 2020年 | 30篇 |
| 2019年 | 29篇 |
| 2018年 | 32篇 |
| 2017年 | 22篇 |
| 2016年 | 21篇 |
| 2015年 | 18篇 |
| 2014年 | 42篇 |
| 2013年 | 61篇 |
| 2012年 | 50篇 |
| 2011年 | 57篇 |
| 2010年 | 36篇 |
| 2009年 | 19篇 |
| 2008年 | 19篇 |
| 2007年 | 33篇 |
| 2006年 | 34篇 |
| 2005年 | 17篇 |
| 2004年 | 14篇 |
| 2003年 | 9篇 |
| 2002年 | 14篇 |
| 2001年 | 3篇 |
| 2000年 | 8篇 |
| 1998年 | 4篇 |
| 1996年 | 6篇 |
| 1995年 | 2篇 |
| 1994年 | 8篇 |
| 1993年 | 4篇 |
| 1992年 | 4篇 |
| 1991年 | 3篇 |
| 1990年 | 5篇 |
| 1989年 | 3篇 |
| 1988年 | 5篇 |
| 1987年 | 3篇 |
| 1986年 | 5篇 |
| 1985年 | 4篇 |
| 1984年 | 8篇 |
| 1983年 | 3篇 |
| 1982年 | 4篇 |
| 1981年 | 6篇 |
| 1980年 | 5篇 |
| 1979年 | 6篇 |
| 1978年 | 6篇 |
| 1977年 | 6篇 |
| 1976年 | 5篇 |
| 1975年 | 3篇 |
| 1973年 | 4篇 |
| 1972年 | 2篇 |
排序方式： 共有767条查询结果，搜索用时 15 毫秒
711.
The steady nonlinear hydromagnetic flow of an incompressible, viscous and electrically conducting fluid with heat transfer over a surface of variable temperature stretching with a power-law velocity in the presence of variable transverse magnetic field is analysed. Utilizing similarity transformation, governing nonlinear partial differential equations are transformed to nonlinear ordinary differential equations and they are numerically solved using fourth-order Runge–Kutta shooting method. Numerical solutions are illustrated graphically by means of graphs. The effects of magnetic field, stretching parameter and Prandtl number on velocity, skin friction, temperature distribution and rate of heat transfer are discussed. 相似文献
712.
Single crystals of L‐ascorbic acid, popularly known as vitamin‐C, were grown from solutions with different solvents and solvent combinations by low temperature solution growth methods. The suitability of different solvents and solvent combinations such as acetone, ethanol, methanol, isopropyl alcohol, water, water + acetone (1:1), water + ethanol (3:1), water + isopropyl alcohol (3:1) and isopropyl alcohol + methanol (1:1) for crystal growth of L‐ascorbic acid was found out by assessing the solubility and crystallization behaviours. Solubility of L‐ascorbic acid in selected solvents and solvent combinations in a range of temperatures was determined by gravimetric method. Solution prepared with water, water + acetone (1:1), water + ethanol (3:1) and water + isopropyl alcohol (3:1) were yielded crystals with tabular, columnar and prismatic habits and their morphologies were evaluated by goniometry. Grown single crystals were characterized with various instrumental techniques such as powder X‐ray diffraction, Fourier infrared spectroscopy, optical transmittance study, differential scanning calorimetry and second harmonic generation studies. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
713.
Bishal Bhuyan;Meghali Devi;Debashree Bora;Siddhartha Sankar Dhar;Rajashree Newar; 《欧洲无机化学杂志》2018,2018(34):3849-3858
In the present study, a new photoactive bimetallic Cu-Au@g-C3N4 catalytic system was designed by impregnating Cu and Au NPs over the graphitic carbon nitrite (g-C3N4) surface. Characterization of the catalyst using multiple techniques illustrated that very small-sized Cu and Au NPs were monodispersed on the g-C3N4 surface, which were obtained by the in situ reduction of the metal salts using sodium borohydride. The as-synthesized bimetallic Cu-Au@g-C3N4 catalyst efficiently catalyzed the hydroxylation of benzene (HOB) via C–H activation under visible light irradiation at room temperature. The dominant role of the synergistic interaction between Cu and Au NPs were further elucidated by high resolution transmission electron microscopy (HR-TEM) studies and X-ray photoelectron spectroscopy (XPS) analysis. This study may provide a new avenue for the preparation of photoactive bimetallic catalysts and offers insight into the synergistic interaction of bimetallic catalytic HOB reactions. 相似文献
714.
715.
Structural aspects of organosilicon(IV) and organotin(IV) complexes with dehydroacetic acid and amino ether Schiff base ligand have been described with the help of elemental analyses, conductance measurements, UV–Vis, infrared, multinuclear magnetic resonance, mass spectroscopy as well as thermogravimetric analysis, and X‐ray diffraction studies. Analysis of data suggested that the Schiff base provides two bidentate NO domains and was coordinated to silicon and tin moiety through the imine nitrogen and hydroxyl oxygen atom. Complexes were found to be nonelectrolytic and monomeric in nature. The thermal decomposition for tin compounds occurred in two steps and resulted into the formation of pure SnO2 as end product. The in vitro biological effects of the synthesized compounds were tested against two Gram‐positive and two Gram‐negative bacteria. The results of biological activity showed that all the complexes have enhanced activity as compared with the corresponding ligand, and compounds 5 , 9 , 11 , 12 , 13 , 15 , 16 , and 17 were more potent than the standard drug ciprofloxacin. Compound 17 exhibited best antibacterial activity with lowest minimum inhibitory concentration value and maximum zone of inhibition. Further, quantitative structure–activity relationship studies pointed out that more stable compound were more active as antibacterial agents. 相似文献
716.
Pathinettam PD Muthukrishnan C Murugesan R 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(3):509-517
EPR spectra of single crystals of Mn(II)-doped sarcosine cadmium chloride and sarcosine cadmium bromide are studied in Q-band and in X-band at room temperature. Two magnetically inequivalent sites are observed in both the lattices in a distorted octahedral environment. The spin-Hamiltonian parameters are extracted and are found to have a rhombic symmetry. The angular variation of the zero-field transitions is simulated for one of the sites with an asymmetric zero-field tensor D = 480 x 10(-4) cm(-1), E = -115 x 10(-4) cm(-1) and a = 10 x 10(-4) cm(-1) for Mn(II) in sarcosine cadmium chloride and with D = 460 x 10(-4) cm(-1) E = -98 x 10(-4) cm(-1) and a = 10 x 10(-4) cm(-1) for Mn(II) in sarcosine cadmium bromide. The observed large value of zero-field tensor is due to the steric effects of the crystal packing caused by the ligands. Matumura's plot predicts an average covalency of 8.8 and 7.7% for the manganese-ligand bond in SCC and SCB lattices respectively. 相似文献
717.
Nandhini Muthukrishnan Stephen Donovan Jean‐Philippe Pellois 《Photochemistry and photobiology》2014,90(5):1034-1042
Upon light irradiation, Fluorophore–cell‐penetrating peptide (Fl‐CPP) conjugates can disrupt the integrity of biological membranes. This activity can in turn be used to photoinduce the disruption of endocytic organelles and promote the delivery of entrapped macromolecules such as proteins or RNAs into live cells. Recent mechanistic studies have shown that ROS production by the fluorophore and a latent lytic ability of CPPs act in synergy to elicit photolysis. However, how the structure of fluorophore‐CPP conjugates impacts this synergistic activity remains unclear. Herein, using red blood cells (RBCs) as a model of biological membranes, we show that the number of arginine residues in a CPP as well as the position of fluorophore with respect to the CPP dramatically affect the photolytic activity of a fluorophore‐CPP conjugate. These factors should therefore be considered for the development of effective photoinducible delivery agents. 相似文献
718.
An efficient synthesis of 4-benzyl cinnolines from aryl phenylallylidene hydrazone is described. In this report aluminium chloride as a Lewis acid catalyst and toluene as a solvent are used for the synthesis. This method is expected to more advantageous than the other reported methods of synthesis of the cinnoline rings because of its low cost, better yield, and benign reaction conditions.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
719.
S.P. Anjali Devi R. Kandasamy 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2000,80(10):697-700
An approximate numerical solution for the steady MHD flow over an infinite horizontal plate in the presence of species concentration and chemical reaction has been obtained by solving the non‐linear governing equations using R. K. Gill's method. The fluid is assumed to be viscous, incompressible, and electrically conducting. A uniform transverse magnetic field is applied. It has been observed that in the presence of chemical reaction (1) the velocity and the concentration decrease with increase of the chemical reaction parameter and vice versa, (2) the velocity decreases and the concentration is uniform with increase of the magnetic parameter and vice versa. 相似文献
720.