全文获取类型
收费全文 | 1173篇 |
免费 | 17篇 |
国内免费 | 3篇 |
专业分类
化学 | 778篇 |
晶体学 | 4篇 |
力学 | 10篇 |
数学 | 264篇 |
物理学 | 137篇 |
出版年
2022年 | 17篇 |
2021年 | 20篇 |
2020年 | 13篇 |
2019年 | 17篇 |
2017年 | 15篇 |
2016年 | 23篇 |
2015年 | 20篇 |
2014年 | 24篇 |
2013年 | 31篇 |
2012年 | 49篇 |
2011年 | 34篇 |
2010年 | 26篇 |
2009年 | 23篇 |
2008年 | 36篇 |
2007年 | 41篇 |
2006年 | 43篇 |
2005年 | 33篇 |
2004年 | 28篇 |
2003年 | 19篇 |
2002年 | 19篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 12篇 |
1997年 | 17篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 21篇 |
1993年 | 18篇 |
1992年 | 24篇 |
1991年 | 21篇 |
1990年 | 24篇 |
1989年 | 28篇 |
1988年 | 11篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 19篇 |
1980年 | 16篇 |
1979年 | 24篇 |
1978年 | 19篇 |
1977年 | 23篇 |
1976年 | 19篇 |
1975年 | 17篇 |
1974年 | 14篇 |
1973年 | 12篇 |
1970年 | 8篇 |
1900年 | 8篇 |
排序方式: 共有1193条查询结果,搜索用时 15 毫秒
951.
952.
953.
Carbon suboxide, C3O2, is crystallized from the melt. According to the X‐ray structure determination the crystal contains two non‐crystallographically equivalent molecules in the asymmetric unit: a = 986.9(2), b = 1206.0(2), c = 516.0(1) pm, space group Pnma. Both molecules are linear. A close inspection of the vibrational amplitudes indicates some systematic deviations from linearity. 相似文献
954.
Konrad Piwakowski Stanisaw P. Radziszowski Sebastian Urbaski 《Journal of Graph Theory》1999,32(1):41-49
With the help of computer algorithms, we improve the lower bound on the edge Folkman number Fe(3, 3; 5) and vertex Folkman number Fv(3, 3; 4), and, thus, show that the exact values of these numbers are 15 and 14, respectively. We also present computer enumeration of all critical graphs. © 1999 John Wiley & Sons, Inc. J Graph Theory 32: 41–49, 1999 相似文献
955.
N2O4 dissolves in IF5 as NO+NO3–, as established by n.m.r spectroscopy, and in the solid state the solvate complex NO+NO3– · IF5 is formed. This contains a double chain of alternating NO+ cations and NO3– anions. (a = 483.4(2), b = 773.9(1), c = 932.6(3) pm, (α = 70.18(2)°, β = 80.90(3)°, (γ = 87.34(2)°, space group P1, Z = 2). 相似文献
956.
957.
A potential energy model is developed to study the intramolecular proton transfer in the enol form of acetylacetone. It makes use of the empirical valence bond approach developed by Warshel to combine standard molecular mechanics potentials for the reactant and product states to reproduce the interconversion between these two states. Most parameters have been fitted to reproduce the key features of an ab initio potential surface obtained from 4-31G* Hartree-Fock calculations. The partial charges have been fitted to reproduce the electrostatic potential surface of 6-31G* Hartree-Fock wave functions, subject to total charge and symmetry constraints, using a fitting procedure based on generalized inverses. The resulting potential energy function reproduces the features most important for proton transfer simulations, while being several orders of magnitude faster in evaluation time than ab initio energy calculations. © 1997 by John Wiley & Sons, Inc. 相似文献
958.
959.
960.
Julian Zubek Ewa Nagrska Joanna Komorowska-Mach Katarzyna Skowroska Konrad Zieliski Joanna Rczaszek-Leonardi 《Entropy (Basel, Switzerland)》2022,24(4)
The present pandemic forced our daily interactions to move into the virtual world. People had to adapt to new communication media that afford different ways of interaction. Remote communication decreases the availability and salience of some cues but also may enable and highlight others. Importantly, basic movement dynamics, which are crucial for any interaction as they are responsible for the informational and affective coupling, are affected. It is therefore essential to discover exactly how these dynamics change. In this exploratory study of six interacting dyads we use traditional variability measures and cross recurrence quantification analysis to compare the movement coordination dynamics in quasi-natural dialogues in four situations: (1) remote video-mediated conversations with a self-view mirror image present, (2) remote video-mediated conversations without a self-view, (3) face-to-face conversations with a self-view, and (4) face-to-face conversations without a self-view. We discovered that in remote interactions movements pertaining to communicative gestures were exaggerated, while the stability of interpersonal coordination was greatly decreased. The presence of the self-view image made the gestures less exaggerated, but did not affect the coordination. The dynamical analyses are helpful in understanding the interaction processes and may be useful in explaining phenomena connected with video-mediated communication, such as “Zoom fatigue”. 相似文献