全文获取类型
收费全文 | 16081篇 |
免费 | 3383篇 |
国内免费 | 1009篇 |
专业分类
化学 | 3745篇 |
晶体学 | 131篇 |
力学 | 3893篇 |
综合类 | 174篇 |
数学 | 2573篇 |
物理学 | 9957篇 |
出版年
2024年 | 34篇 |
2023年 | 136篇 |
2022年 | 276篇 |
2021年 | 328篇 |
2020年 | 449篇 |
2019年 | 414篇 |
2018年 | 389篇 |
2017年 | 498篇 |
2016年 | 560篇 |
2015年 | 554篇 |
2014年 | 811篇 |
2013年 | 1569篇 |
2012年 | 957篇 |
2011年 | 1162篇 |
2010年 | 894篇 |
2009年 | 947篇 |
2008年 | 1004篇 |
2007年 | 1019篇 |
2006年 | 941篇 |
2005年 | 913篇 |
2004年 | 863篇 |
2003年 | 768篇 |
2002年 | 623篇 |
2001年 | 589篇 |
2000年 | 485篇 |
1999年 | 393篇 |
1998年 | 415篇 |
1997年 | 334篇 |
1996年 | 276篇 |
1995年 | 282篇 |
1994年 | 218篇 |
1993年 | 236篇 |
1992年 | 195篇 |
1991年 | 167篇 |
1990年 | 121篇 |
1989年 | 118篇 |
1988年 | 116篇 |
1987年 | 80篇 |
1986年 | 55篇 |
1985年 | 51篇 |
1984年 | 47篇 |
1983年 | 18篇 |
1982年 | 41篇 |
1981年 | 35篇 |
1980年 | 15篇 |
1979年 | 28篇 |
1976年 | 6篇 |
1973年 | 10篇 |
1972年 | 6篇 |
1971年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
《Mendeleev Communications》2022,32(5):597-600
Calorimetric monitoring of the autoclave reaction N2O4 + C2H4 at –85 to +10 °C under argon pressure 10–30 bar revealed that the exothermic chemical reaction started at temperatures above –52 °C at 10 bar, whereas an intensive exothermic reaction started at –85 °C and pressure of 30 bar. IR study showed that oligo/polynitroethylene was formed at 30 bar, while carbonyl and hydroxy compound as well as nitrate R–ONO2 formation occurred upon processing at 10 bar. 相似文献
2.
当煤层上方为坚硬顶板时,在工作面回采期间容易出现大面积悬顶,导致巷旁充填体出现大变形破坏,极大威胁采煤安全.为解决这一问题,以某矿1205工作面沿空留巷为工程背景,分析了爆炸围岩裂隙范围和坚硬顶板破断特征,建立了切顶卸压围岩结构力学模型,研究表明,相邻炮孔爆炸后,炮孔间裂隙互相贯穿,降低了顶板强度,同时当切顶角为15°时,巷道稳定性较好.工程实践结果表明:采用爆破切顶技术后,顶板下沉量减小了62.3%,较好地保证了围岩稳定性. 相似文献
3.
Tetsuo Irifune Chiaki Ueda Shohei Ohshita Hiroaki Ohfuji Takehiro Kunimoto Toru Shinmei 《高压研究》2020,40(1):96-106
ABSTRACTNano-polycrystalline diamond (NPD) with various grain sizes has been synthesized from glassy carbon at pressures 15–25?GPa and temperatures 1700–2300°C using multianvil apparatus. The minimum temperature for the synthesis of pure NPD, below which a small amount of compressed graphite was formed, significantly increased with pressure from ~1700°C at 15?GPa to ~1900°C at 25?GPa. The NPD having grain sizes less than ~50?nm was synthesized at temperatures below ~2000°C at 15?GPa and ~2300°C at 25?GPa, above which significant grain growth was observed. The grain size of NPD decreases with increasing pressure and decreasing temperature, and the pure NPD with grain sizes less than 10?nm is obtained in a limited temperature range around 1800–2000°C, depending on pressure. The pure NPD from glassy carbon is highly transparent and exhibits a granular nano-texture, whose grain size is tunable by selecting adequate pressure and temperature conditions. 相似文献
4.
5.
Tsuguo SUNAMURA 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2015,91(9):481-500
Substantial progress in research on the recession of coastal cliffs composed of soft materials has been made in recent years and data with higher accuracy have been accumulated. This paper provides the state of the art review in the recession studies and highlights two new findings obtained from the reanalysis of existing data. The review topics are: episodic and localized nature of cliff recession; the development of cliffline; the relationship between cliff height and recession rate; mechanisms of cliff toe erosion by waves; a fundamental equation for wave-induced toe erosion; factors controlling toe erosion; and slope instabilities and mass movements. The findings are presented on (1) the temporal change in cliffline recession mode and (2) the effect of beach sediment at the cliff base on the cliff erosion. 相似文献
6.
7.
Bobby Wilson 《偏微分方程通讯》2015,40(8):1521-1542
This article explores the questions of long time orbital stability in high order Sobolev norms of plane wave solutions to the NLSE in the defocusing case. 相似文献
8.
The zero dissipation limit of the one-dimensional non-isentropic micropolar equations is studied in this paper. If the given rarefaction wave which connects to vacuum at one side, a sequence of solution to the micropolar equations can be constructed which converge to the above rarefaction wave with vacuum as the viscosity and the heat conduction coefficient tend to zero. Moreover, the uniform convergence rate is obtained. The key point in our analysis is how to control the degeneracies in the vacuum region in the zero dissipation limit process. 相似文献
9.
《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2020,37(2):417-456
We study the energy-critical nonlinear wave equation in the presence of an inverse-square potential in dimensions three and four. In the defocussing case, we prove that arbitrary initial data in the energy space lead to global solutions that scatter. In the focusing case, we prove scattering below the ground state threshold. 相似文献
10.
阐明了引入溶剂渗透因子的必要性,较详细地介绍了两种渗透因子及它们间的关系。 相似文献