全文获取类型
收费全文 | 3256篇 |
免费 | 79篇 |
国内免费 | 6篇 |
专业分类
化学 | 2634篇 |
晶体学 | 44篇 |
力学 | 9篇 |
数学 | 125篇 |
物理学 | 529篇 |
出版年
2021年 | 21篇 |
2020年 | 26篇 |
2019年 | 23篇 |
2018年 | 22篇 |
2017年 | 18篇 |
2016年 | 45篇 |
2015年 | 40篇 |
2014年 | 58篇 |
2013年 | 146篇 |
2012年 | 110篇 |
2011年 | 127篇 |
2010年 | 61篇 |
2009年 | 93篇 |
2008年 | 146篇 |
2007年 | 171篇 |
2006年 | 182篇 |
2005年 | 177篇 |
2004年 | 161篇 |
2003年 | 149篇 |
2002年 | 125篇 |
2001年 | 66篇 |
2000年 | 71篇 |
1999年 | 39篇 |
1998年 | 46篇 |
1997年 | 33篇 |
1996年 | 35篇 |
1995年 | 25篇 |
1994年 | 46篇 |
1993年 | 35篇 |
1992年 | 53篇 |
1991年 | 35篇 |
1990年 | 37篇 |
1989年 | 24篇 |
1988年 | 42篇 |
1987年 | 42篇 |
1986年 | 44篇 |
1985年 | 66篇 |
1984年 | 52篇 |
1983年 | 30篇 |
1982年 | 65篇 |
1981年 | 59篇 |
1980年 | 55篇 |
1979年 | 53篇 |
1978年 | 37篇 |
1977年 | 43篇 |
1976年 | 37篇 |
1975年 | 50篇 |
1974年 | 46篇 |
1973年 | 42篇 |
1968年 | 27篇 |
排序方式: 共有3341条查询结果,搜索用时 15 毫秒
951.
952.
953.
954.
955.
Chiaki Hirose Nobuyuki Watanabe Hiroyoshi Yamamoto Akihide Wada Kazunari Domen T. Ohtake Norihisa Mino 《中国化学会会志》1994,41(3):275-278
The vibrational spectroscopy by way of vibrational sum-frequency generation (VSFG) has been made of formic acid adsorbed on MgO(001) surface and of n-alkyltrichlorosilanes chemisorbed on quartz plates. It was revealed that the species on the MgO surface was formate ion (HCOO+) with CH bonds standing vertical to the surface and that the different adsorption sites showed up on repeated cycles of adsorption-desorption processes. The results of chemisorbed films indicated that the g-t and/or g-t-g′ conformational scquences of n-alkyl chains occurred more frequently by the length of alkyl chain and that the surface hydroxyls, which are the sites of chemisorption, are ripped off by pre-exposure of substrate to oxygen plasma. 相似文献
956.
957.
958.
Kenji Wada Yasuhiko Satomura Hiroshi Kamie Takafumi Kiuchi Hiromichi Horinaka Yoshio Cho Tokuo Umeda Kenji Nakamura 《Optical Review》2000,7(5):432-435
Aiming at the realization of optical computed tomography (optical CT), a compact system comprised of two cw-lasers and a detector was proposed for the extraction of quasi-straightforward propagating photons from scattered light transmitting through a scattering medium. The extraction ability of the system based on the sum-frequency generation technique was investigated using a standard scattering medium of Intralipid-10% aqueous solution and was found to be 78 dB in dynamic range. The optical CT image of absorbers placed in the scattering medium was successfully obtained with high contrast using the proposed system. 相似文献
959.
Toshihide Baba Yuki Morikawa Norito Komatsu Toshiro Takahashi Hisashi Sugisawa Yoshio Ono 《Research on Chemical Intermediates》2000,26(1):13-20
The dynamic properties of protons in H-[Ga]-ZSM-5, H-[B]-ZSM-5 and H-[Al-B]-ZSM-5 were compared with that of protons in H-[Al]-ZSM-5
by temperature dependence of 1H MAS NMR in the range of 298 k and 473 K. The temperature dependence of the line width of 1H MAS NMR reveals that protons in H-[Ga]-ZSM-5 were more mobile than those in H-[Al]-ZSM-5 at temperature as low as 373 K.
The protons in H-[B]-ZSM-5 were not mobile at 473 K and fixed in the zeolite frame work as the bridging hydroxyl groups, ≡B-OH-Si≡.
The thermal motion of protons in ≡Al-OH-Si≡ was suppressed by introducing B3+ cations into the framework of H-[Al]-ZSM-5. 相似文献
960.
Yoshio Toda Takashi Ohno Fumikazu Hatayama Hisashi Miyata 《Reaction Kinetics and Catalysis Letters》2000,71(1):159-164
Acidity and structure of Ca-doped V2O5/ZrO2 catalysts have been studied by FTIR. Both Lewis and Brønsted acidity decreased with Ca loading. New surface vanadate species seemed to be formed by Ca addition. 相似文献