全文获取类型
收费全文 | 2375篇 |
免费 | 100篇 |
国内免费 | 8篇 |
专业分类
化学 | 1617篇 |
晶体学 | 13篇 |
力学 | 103篇 |
数学 | 343篇 |
物理学 | 407篇 |
出版年
2023年 | 28篇 |
2022年 | 22篇 |
2021年 | 54篇 |
2020年 | 59篇 |
2019年 | 58篇 |
2018年 | 41篇 |
2017年 | 29篇 |
2016年 | 71篇 |
2015年 | 63篇 |
2014年 | 59篇 |
2013年 | 103篇 |
2012年 | 147篇 |
2011年 | 169篇 |
2010年 | 84篇 |
2009年 | 70篇 |
2008年 | 152篇 |
2007年 | 136篇 |
2006年 | 147篇 |
2005年 | 126篇 |
2004年 | 67篇 |
2003年 | 74篇 |
2002年 | 47篇 |
2001年 | 39篇 |
2000年 | 24篇 |
1999年 | 20篇 |
1998年 | 32篇 |
1997年 | 21篇 |
1996年 | 23篇 |
1995年 | 18篇 |
1994年 | 18篇 |
1993年 | 21篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 14篇 |
1989年 | 16篇 |
1988年 | 13篇 |
1987年 | 19篇 |
1986年 | 25篇 |
1985年 | 15篇 |
1984年 | 23篇 |
1983年 | 16篇 |
1982年 | 20篇 |
1981年 | 28篇 |
1980年 | 29篇 |
1978年 | 22篇 |
1977年 | 24篇 |
1976年 | 21篇 |
1975年 | 16篇 |
1974年 | 11篇 |
1972年 | 11篇 |
排序方式: 共有2483条查询结果,搜索用时 78 毫秒
81.
Morgan A. Higgins Christopher R. Maroon Jacob Townsend Xinyi Wang Konstantinos D. Vogiatzis Brian K. Long 《Journal of polymer science. Part A, Polymer chemistry》2020,58(18):2644-2653
Polymeric membranes have shown tremendous promise for the separation of CO2 from flue gas streams. However, few systematic studies have been conducted to better understand the impact that chemical functionalities have on membrane-based gas separation performance. To address this gap, we herein describe the synthesis and gas separation performance of a series of vinyl-addition polynorbornenes bearing various CO2-philic functional groups. To facilitate direct comparison between functional groups, each material was designed to maintain a common polymer backbone. Though the incorporation of CO2-philic moieties within a dense polymeric membrane is frequently hypothesized to enhance CO2 solubility, and thereby increase CO2/N2 selectivity, our results demonstrate that the incorporation of CO2-philic groups onto a common polymer backbone do not necessarily result in increased gas separation performance. Experimental and computational results demonstrate that the incorporation of amidoxime groups onto a polynorbornene backbone increase CO2/N2 selectivity, whereas commonly employed ethereal side chains only increased permeability. 相似文献
82.
83.
Maywald Jacob D. Reiman Adam D. Overstreet Robert E. Johnson Alan W. 《Annals of Operations Research》2019,274(1-2):425-445
Annals of Operations Research - We consider the use of the new C-130J-30 aircraft for long distance (strategic) cargo movement. Currently, only large aircraft, the C-5 and the C-17, are identified... 相似文献
84.
85.
Different methods for the interpretation of linear dichroic spectra of molecules incorporated in uniaxial matrices are discussed. A method based on the combination of both polarized absorption and emission measurements is described for the resolution of absorption and emission spectra into their different polarized components, and for the investigation of molecular distributions in the oriented matrix. The distributions of some planar molecules of different shapes incorporated in stretched polyethylene films are presented. 相似文献
86.
87.
Recent measurements of charge-dependent azimuthal correlations in high-energy heavy-ion collisions have indicated charge-separation signals perpendicular to the reaction plane, and have been related to the chiral magnetic effect(CME). However, the correlation signal is contaminated with the background caused by the collective motion(flow) of the collision system, and an effective approach is needed to remove the flow background from the correlation. We present a method study with simplified Monte Carlo simulations and a multi-phase transport model,and develop a scheme to reveal the true CME signal via event-shape engineering with the flow vector of the particles of interest. 相似文献
88.
Thomas Weymuth Moritz P. Haag Karin Kiewisch Sandra Luber Stephan Schenk Christoph R. Jacob Carmen Herrmann Johannes Neugebauer Markus Reiher 《Journal of computational chemistry》2012,33(27):2186-2198
We present the software package MO VI PAC for calculations of vibrational spectra, namely infrared, Raman, and Raman Optical Activity (ROA) spectra, in a massively parallelized fashion. MO VI PAC unites the latest versions of the programs SNF and AKIRA alongside with a range of helpful add‐ons to analyze and interpret the data obtained in the calculations. With its efficient parallelization and meta‐program design, MO VI PAC focuses in particular on the calculation of vibrational spectra of very large molecules containing on the order of a hundred atoms. For this purpose, it also offers different subsystem approaches such as Mode‐ and Intensity‐Tracking to selectively calculate specific features of the full spectrum. Furthermore, an approximation to the entire spectrum can be obtained using the Cartesian Tensor Transfer Method. We illustrate these capabilities using the example of a large π‐helix consisting of 20 (S)‐alanine residues. In particular, we investigate the ROA spectrum of this structure and compare it to the spectra of α‐ and 310‐helical analogs. © 2012 Wiley Periodicals, Inc. 相似文献
89.
Thermodynamic properties of Dysprosium rhodite (DyRhO3) are measured in the temperature range from 900 to 1,300 K using a solid-state electrochemical cell incorporating yttria-stabilized zirconia as the electrolyte. The standard Gibbs free energy of formation of DyRhO3 with O-type perovskite structure from its components binary oxides, Dysprosia with C-rare earth structure and β-Rh2O3 with orthorhombic structure, can be represented by the equation: $$ {{{\varDelta G_{{f\left( {ox} \right)}}^o\left( {\pm 182} \right)}} \left/ {{{\mathrm{J} ~ \mathrm{mo}}{{\mathrm{l}}^{{ - 1}}}}} \right.} = - 52710 + 3.821\left( {{{T} \left/ {\mathrm{K}} \right.}} \right). $$ By using the thermodynamic data for DyRhO3 from experiment and auxiliary data for other phases from the literature, the phase relations in the system Dy-Rh-O are computed. Thermodynamic data for intermetallic phases in the binary system Dy-Rh, required for constructing the chemical potential diagrams, are evaluated using calorimetric data available in the literature for three intermetallics and Miedema’s model, consistent with the phase diagram. The results are presented in the form of Gibbs triangle, oxygen potential–composition diagram, and three-dimensional chemical potential diagram at 1,273 K. Temperature–composition diagrams at constant oxygen partial pressures are also developed. The decomposition temperature of DyRhO3 is 1,732 (±2.5) K in pure oxygen and 1,624 (±2.5) K and in air at standard pressure. 相似文献
90.
Mostafa Mesgar Dr. Payam Kaghazchi Prof. Dr. Timo Jacob Dr. Ernesto Pichardo‐Pedrero Dr. Margret Giesen Dr. Ernesto Pichardo‐Pedrero Dr. Margret Giesen Prof. Dr. Harald Ibach Dr. Noelia B. Luque Prof. Dr. Wolfgang Schmickler 《Chemphyschem》2013,14(1):233-236
Motivated by experimental studies of two‐dimensional Ostwald ripening on Au(100) electrodes in chlorine‐containing electrolytes, we have studied diffusion processes using density functional theory. We find that chlorine has a propensity to temporary form AuCl complexes, which diffuse significantly faster than gold adatoms. With and without chlorine, the lowest activation energy is found for the exchange mechanism. Chlorine furthermore reduces the activation energy for the detachment from kink sites. Kinetic Monte Carlo simulations were performed on the basis of extensive density functional theory calculations. The island‐decay rate obtained from these Monte Carlo simulations, as well as the decay rate obtained from the theoretical activation energies and frequency factors when inserted into analytical solutions for Ostwald ripening, are in agreement with experimental island‐decay rates in chlorine‐containing electrolytes. 相似文献