全文获取类型
收费全文 | 357516篇 |
免费 | 2664篇 |
国内免费 | 879篇 |
专业分类
化学 | 159979篇 |
晶体学 | 5484篇 |
力学 | 19806篇 |
综合类 | 11篇 |
数学 | 69267篇 |
物理学 | 106512篇 |
出版年
2020年 | 1793篇 |
2019年 | 2014篇 |
2018年 | 18781篇 |
2017年 | 19396篇 |
2016年 | 12167篇 |
2015年 | 3770篇 |
2014年 | 4039篇 |
2013年 | 9707篇 |
2012年 | 13515篇 |
2011年 | 27773篇 |
2010年 | 16825篇 |
2009年 | 17268篇 |
2008年 | 22280篇 |
2007年 | 27170篇 |
2006年 | 7172篇 |
2005年 | 13769篇 |
2004年 | 10104篇 |
2003年 | 9995篇 |
2002年 | 7114篇 |
2001年 | 6526篇 |
2000年 | 5201篇 |
1999年 | 3710篇 |
1998年 | 2975篇 |
1997年 | 2862篇 |
1996年 | 2901篇 |
1995年 | 2635篇 |
1994年 | 2489篇 |
1993年 | 2327篇 |
1992年 | 2954篇 |
1991年 | 2863篇 |
1990年 | 2799篇 |
1989年 | 2847篇 |
1988年 | 2863篇 |
1987年 | 2864篇 |
1986年 | 2723篇 |
1985年 | 3462篇 |
1984年 | 3460篇 |
1983年 | 2744篇 |
1982年 | 2856篇 |
1981年 | 2906篇 |
1980年 | 2674篇 |
1979年 | 3029篇 |
1978年 | 3027篇 |
1977年 | 3056篇 |
1976年 | 2919篇 |
1975年 | 2640篇 |
1974年 | 2582篇 |
1973年 | 2578篇 |
1972年 | 1760篇 |
1968年 | 1811篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
122.
123.
124.
Shaobo Cheng Vidushi Sharma Altug S. Poyraz Lijun Wu Xing Li Amy C. Marschilok Esther S. Takeuchi Kenneth J. Takeuchi Marivi Fernndez-Serra Yimei Zhu 《Chemical science》2020,11(19):4991
Tunneled metal oxides such as α-Mn8O16 (hollandite) have proven to be compelling candidates for charge-storage materials in high-density batteries. In particular, the tunnels can support one-dimensional chains of K+ ions (which act as structure-stabilizing dopants) and H2O molecules, as these chains are favored by strong H-bonds and electrostatic interactions. In this work, we examine the role of water molecules in enhancing the stability of K+-doped α-Mn8O16 (cryptomelane). The combined experimental and theoretical analyses show that for high enough concentrations of water and tunnel-ions, H2O displaces K+ ions from their natural binding sites. This displacement becomes energetically favorable due to the formation of K2+ dimers, thereby modifying the stoichiometric charge of the system. These findings have potentially significant technological implications for the consideration of cryptomelane as a Li+/Na+ battery electrode. Our work establishes the functional role of water in altering the energetics and structural properties of cryptomelane, an observation that has frequently been overlooked in previous studies.Water displaces potassium ions and initiates the formation of a homonuclear dimer ion (K2+) in the tunnels of hollandite. 相似文献
125.
126.
Pan Huang Dawen Xu Robert M. Reich Felix Kaiser Boping Liu Fritz E. Kühn 《Tetrahedron letters》2019,60(24):1574-1577
A first example of an Et2Zn mediated silylation of 1-aklynes is reported. A series of functional groups are tolerated in this reaction. Mechanistic studies support Zn alkynilides as intermediates in the reaction. This reaction protocol provides a practical method for the preparation of alkynylsilanes and expands the application of organometallic zinc in organic synthesis. 相似文献
127.
128.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献
129.
N. I. Golovina G. N. Nechiporenko G. G. Nemtsev G. P. Dolganova V. P. Roshchupkin D. B. Lempert G. B. Manelis 《Russian Journal of Applied Chemistry》2007,80(1):24-30
Methods for phase stabilization of ammonium nitrate were sought for in order to considerably expand the application area of this oxidizing agent in various-purpose self-combustible formulations, including that in a new generation of gas-generating formulations for automobile air bags. New methods for stabilization of ammonium nitrate were studied and, in particular, a search was made for organic compounds that can stabilize ammonium nitrate even at their low content. The mechanism of phase state stabilization of ammonium nitrate by compounds of this kind was examined. 相似文献
130.
Yu. V. Pokonova 《Russian Journal of Applied Chemistry》2007,80(12):2163-2164
Kinetic, sorption and selectivity properties of commercial adsorbents are improved by adding petroleum residues (tar asphaltene concentrates) 13% of whole mass. Obtained adsorbents can be used for selective extraction of nobel metals from multicomponent polymetallic solutions of heavy metals and fro sewages purification for removing arsenic. 相似文献