全文获取类型
收费全文 | 2940篇 |
免费 | 113篇 |
国内免费 | 10篇 |
专业分类
化学 | 2289篇 |
晶体学 | 60篇 |
力学 | 22篇 |
综合类 | 1篇 |
数学 | 155篇 |
物理学 | 536篇 |
出版年
2022年 | 21篇 |
2021年 | 26篇 |
2020年 | 29篇 |
2019年 | 51篇 |
2018年 | 20篇 |
2017年 | 16篇 |
2016年 | 66篇 |
2015年 | 50篇 |
2014年 | 82篇 |
2013年 | 136篇 |
2012年 | 149篇 |
2011年 | 165篇 |
2010年 | 104篇 |
2009年 | 82篇 |
2008年 | 159篇 |
2007年 | 175篇 |
2006年 | 171篇 |
2005年 | 185篇 |
2004年 | 158篇 |
2003年 | 132篇 |
2002年 | 104篇 |
2001年 | 61篇 |
2000年 | 69篇 |
1999年 | 46篇 |
1998年 | 39篇 |
1997年 | 34篇 |
1996年 | 50篇 |
1995年 | 35篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 47篇 |
1991年 | 34篇 |
1990年 | 29篇 |
1989年 | 24篇 |
1988年 | 39篇 |
1987年 | 18篇 |
1986年 | 19篇 |
1985年 | 40篇 |
1984年 | 27篇 |
1983年 | 27篇 |
1982年 | 33篇 |
1981年 | 40篇 |
1980年 | 25篇 |
1979年 | 47篇 |
1978年 | 22篇 |
1977年 | 14篇 |
1976年 | 14篇 |
1975年 | 16篇 |
1974年 | 18篇 |
1973年 | 27篇 |
排序方式: 共有3063条查询结果,搜索用时 15 毫秒
1.
Watanabe Sou Senzaki Tatsuya Shibata Atsuhiro Nomura Kazunori Takeuchi Masayuki Nakatani Kiyoharu Matsuura Haruaki Horiuchi Yusuke Arai Tsuyoshi 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(3):1273-1277
Journal of Radioanalytical and Nuclear Chemistry - Extraction chromatography flow-sheet employing octyl(phenyl)-N,N-diisobutylcarbonoylmethylphosphine oxide and bis(2-ethylhexyl) hydrogen phosphate... 相似文献
2.
Annals of the Institute of Statistical Mathematics - 相似文献
3.
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
4.
Three new cytotoxic polyacetylenes, PQ-1 (1), PQ-2 (2) and PQ-3 (3), have been isolated from Panax quinquefolium. The structures of these acetylenes were determined by analyses of their 1H-1H and 1H-13C COSY spectra. All these compounds exhibited strong cytotoxic activities against leukemia cells (L 1210) in tissue culture. 相似文献
5.
6.
7.
Let Cld
AW
(X) be the hyperspace of nonempty closed subsets of a normed linear space X with the Attouch–Wets topology. It is shown that the space Cld
AW
(X) and its various subspaces are AR's. Moreover, if X is an infinite-dimensional Banach space with weight w(X) then Cld
AW
(X) is homeomorphic to a Hilbert space with weight 2
w(X). 相似文献
8.
9.
A multi-layer chip inductor (MCI) was fabricated using polycrystalline Li–Zn–Cu–Mn ferrite and the green-sheet technique, and its complex impedance spectrum was evaluated with the help of numerical calculations. The complex impedance spectra of the MCI component using Ni–Zn–Cu ferrite, which have been widely used for this application, were very sensitive to the residual stress and deviated much from the calculated values; however, it was found that the complex impedance spectrum of the MCI component using Li–Zn–Cu–Mn ferrite is quite well reproduced by calculation, where the complex permittivity and permeability of the polycrystalline ferrite as well as the MCI dimensions, were used. It implied that the magneto-striction effect was negligible in case of MCI using Li–Zn–Cu–Mn ferrite, and that the difference was related to magneto-strictive coefficient of the polycrystalline ferrite. Consequently, utilization of Li–Zn–Cu–Mn ferrite enabled us to easily design the complex impedance of MCI component. 相似文献
10.
A. Noda S. Nakamura Y. Iwashita S. Sakabe M. Hashida T. Shirai S. Shimizu H. Tongu H. Ito H. Souda A. Yamazaki M. Tanabe H. Daido M. Mori M. Kado A. Sagisaka K. Ogura M. Nishiuchi S. Orimo Y. Hayashi A. Yogo S. Bulanov T. Esirkepov A. Nagashima T. Kimura T. Tajima T. Takeuchi K. Matsukado A. Fukumi Z. Li 《Laser Physics》2006,16(4):647-653
In order to widely spread out particle beams utilized in cancer therapy, laser-produced ions are developed as the injection beam for an ion synchrotron dedicated for cancer therapy. Such a laser ion source is expected to contribute largely to the realization of compactness of the size and low cost of the cancer therapy accelerator. The energy spectrum of the laser-produced ions, however, has no peak, but their intensities decrease exponentially according to the increase of the energy. For the purpose of modifying such a situation, we have proposed a scheme to rotate the beam in the longitudinal phase space with the use of the RF electric field, which is phase-adjusted with the pulse laser. We aim for a reduction of the energy spread of ± 5% selected by an energy analyzer and slits to ±1% by such phase rotation. For this purpose, a quarter wavelength resonator with two gaps with the same resonant frequency as the source laser has already been fabricated, together with its RF power source. The above phase rotation system and its recent experimental realization are presented. 相似文献