全文获取类型
收费全文 | 1442774篇 |
免费 | 29916篇 |
国内免费 | 7823篇 |
专业分类
化学 | 739314篇 |
晶体学 | 20604篇 |
力学 | 76679篇 |
综合类 | 108篇 |
数学 | 249183篇 |
物理学 | 394625篇 |
出版年
2021年 | 13615篇 |
2020年 | 16040篇 |
2019年 | 16178篇 |
2018年 | 14598篇 |
2016年 | 29059篇 |
2015年 | 21189篇 |
2014年 | 30758篇 |
2013年 | 74972篇 |
2012年 | 43928篇 |
2011年 | 44964篇 |
2010年 | 40059篇 |
2009年 | 41433篇 |
2008年 | 42517篇 |
2007年 | 39241篇 |
2006年 | 43163篇 |
2005年 | 36185篇 |
2004年 | 36090篇 |
2003年 | 33069篇 |
2002年 | 33508篇 |
2001年 | 34130篇 |
2000年 | 28262篇 |
1999年 | 24215篇 |
1998年 | 21744篇 |
1997年 | 21571篇 |
1996年 | 21457篇 |
1995年 | 19452篇 |
1994年 | 18929篇 |
1993年 | 18507篇 |
1992年 | 19167篇 |
1991年 | 19316篇 |
1990年 | 18513篇 |
1989年 | 18493篇 |
1988年 | 18135篇 |
1987年 | 17957篇 |
1986年 | 16988篇 |
1985年 | 23323篇 |
1984年 | 24283篇 |
1983年 | 20342篇 |
1982年 | 21942篇 |
1981年 | 21125篇 |
1980年 | 20457篇 |
1979年 | 20914篇 |
1978年 | 22033篇 |
1977年 | 21700篇 |
1976年 | 21468篇 |
1975年 | 20230篇 |
1974年 | 19920篇 |
1973年 | 20321篇 |
1972年 | 14803篇 |
1967年 | 12970篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
Kazakova E. F. Dmitrieva N. E. Zvereva N. L. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(2):341-344
Russian Journal of Physical Chemistry A - Rapidly quenched alloys of aluminum with cobalt and zirconium are investigated using a combination of means of physicochemical analysis to study the... 相似文献
172.
International Applied Mechanics - The theorems (statements) on the existence of attractor are proved. A generalized Shilnikov theorem is formulated. In the expression for the saddle of a homoclinic... 相似文献
173.
Mathematical Notes - 相似文献
174.
The growth-fragmentation equation describes a system of growing and dividing particles, and arises in models of cell division, protein polymerisation and even telecommunications protocols. Several important questions about the equation concern the asymptotic behaviour of solutions at large times: at what rate do they converge to zero or infinity, and what does the asymptotic profile of the solutions look like? Does the rescaled solution converge to its asymptotic profile at an exponential speed? These questions have traditionally been studied using analytic techniques such as entropy methods or splitting of operators. In this work, we present a probabilistic approach: we use a Feynman–Kac formula to relate the solution of the growth-fragmentation equation to the semigroup of a Markov process, and characterise the rate of decay or growth in terms of this process. We then identify the Malthus exponent and the asymptotic profile in terms of a related Markov process, and give a spectral interpretation in terms of the growth-fragmentation operator and its dual. 相似文献
175.
176.
177.
Cavitation erosion is caused in solids exposed to strong pressure waves developing in an adjacent fluid field. The knowledge of the transient distribution of stresses in the solid is important to understand the cause of damaging by comparisons with breaking points of the material. The modeling of this problem requires the coupling of the models for the fluid and the solid. For this purpose, we use a strategy based on the solution of coupled Riemann problems that has been originally developed for the coupling of 2 fluids. This concept is exemplified for the coupling of a linear elastic structure with an ideal gas. The coupling procedure relies on the solution of a nonlinear equation. Existence and uniqueness of the solution is proven. The coupling conditions are validated by means of quasi‐1D problems for which an explicit solution can be determined. For a more realistic scenario, a 2D application is considered where in a compressible single fluid, a hot gas bubble at low pressure collapses in a cold gas at high pressure near an adjacent structure. 相似文献
178.
179.
180.
Chemical versus Electrochemical Synthesis of Carbon Nano‐onion/Polypyrrole Composites for Supercapacitor Electrodes
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Olena Mykhailiv Monika Imierska Martyna Petelczyc Prof. Dr. Luis Echegoyen Dr. Marta E. Plonska‐Brzezinska 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5783-5793
The development of high‐surface‐area carbon electrodes with a defined pore size distribution and the incorporation of pseudo‐active materials to optimize the overall capacitance and conductivity without destroying the stability are at present important research areas. Composite electrodes of carbon nano‐onions (CNOs) and polypyrrole (Ppy) were fabricated to improve the specific capacitance of a supercapacitor. The carbon nanostructures were uniformly coated with Ppy by chemical polymerization or by electrochemical potentiostatic deposition to form homogenous composites or bilayers. The materials were characterized by transmission‐ and scanning electron microscopy, differential thermogravimetric analyses, FTIR spectroscopy, piezoelectric microgravimetry, and cyclic voltammetry. The composites show higher mechanical and electrochemical stabilities, with high specific capacitances of up to about 800 F g?1 for the CNOs/SDS/Ppy composites (chemical synthesis) and about 1300 F g?1 for the CNOs/Ppy bilayer (electrochemical deposition). 相似文献