全文获取类型
收费全文 | 3852篇 |
免费 | 83篇 |
国内免费 | 12篇 |
专业分类
化学 | 2673篇 |
晶体学 | 52篇 |
力学 | 66篇 |
数学 | 194篇 |
物理学 | 962篇 |
出版年
2022年 | 18篇 |
2021年 | 28篇 |
2020年 | 59篇 |
2019年 | 55篇 |
2018年 | 43篇 |
2017年 | 28篇 |
2016年 | 53篇 |
2015年 | 58篇 |
2014年 | 73篇 |
2013年 | 176篇 |
2012年 | 154篇 |
2011年 | 190篇 |
2010年 | 127篇 |
2009年 | 126篇 |
2008年 | 197篇 |
2007年 | 233篇 |
2006年 | 213篇 |
2005年 | 164篇 |
2004年 | 131篇 |
2003年 | 146篇 |
2002年 | 143篇 |
2001年 | 111篇 |
2000年 | 127篇 |
1999年 | 78篇 |
1998年 | 50篇 |
1997年 | 52篇 |
1996年 | 45篇 |
1995年 | 45篇 |
1994年 | 45篇 |
1993年 | 58篇 |
1992年 | 51篇 |
1991年 | 49篇 |
1990年 | 36篇 |
1989年 | 49篇 |
1988年 | 51篇 |
1987年 | 42篇 |
1986年 | 35篇 |
1985年 | 49篇 |
1984年 | 54篇 |
1983年 | 49篇 |
1982年 | 47篇 |
1981年 | 33篇 |
1980年 | 35篇 |
1979年 | 50篇 |
1978年 | 43篇 |
1977年 | 47篇 |
1976年 | 18篇 |
1975年 | 26篇 |
1974年 | 30篇 |
1967年 | 16篇 |
排序方式: 共有3947条查询结果,搜索用时 15 毫秒
961.
962.
H. Matsuoka Y. Watanabe M. Maeda T. Kawakami Y. Kubota 《Physica C: Superconductivity and its Applications》2009,469(15-20):1189-1191
We fabricated MgB2 bulks by an in situ Mg diffusive reaction method from compacted B and compacted mixtures of Mg and B respectively. All samples were sintered at 1100 °C for 2 h. MgO impurity phase, density, and critical current density (Jc) were found to be dependent of the starting amount of mixing Mg powder. We also found that the MgO formation in MgB2 matrix was not mainly attributed to the starting amount of additional Mg powder for Mg diffusive reaction. This indicates that MgO presented in the starting Mg powder is hardly diffused into compacted B. 相似文献
963.
We have developed a novel electrolytic system based on the anion exchange reaction between KCl and Amberlyst A26. It was demonstrated by preparative electrolysis experiments as well as cyclic voltammetry that the anion exchange reaction offers a unique electrolytic system for electroreduction of organic compounds. On the basis of the electrolytic system, electroreduction of aromatic carbonyl compounds was successfully achieved by using an undivided cell to provide the corresponding coupling products as pinacols in good to high yields with high diastereoselectivity. 相似文献
964.
965.
Jorge S. Ayala-Arenas Reneu L. Andrioli Jr S. Watanabe M. Matsuoka B. C. Bhatt 《Radiation Physics and Chemistry》2001,61(3-6):417-419
Morganite, a pink beryl with the chemical formula Be3Al2Si6O18, was investigated in terms of its thermally stimulated luminescence (TL) and electron paramagnetic resonance (EPR) properties due to point defects. Atomic hydrogen H°-centers were induced by γ-radiation and shown to be responsible for a 165°C TL peak. The Fe3+-center concentration was found to increase with γ-dose, observed by both TL and EPR measurements, decreasing with thermal treatments beyond 250°C. A mechanism for emission around 315°C is proposed. 相似文献
966.
Hiromitsu Kiriyama Michiaki Mori Yoshiki Nakai Takuya Shimomura Manabu Tanoue Atushi Akutsu Hajime Okada Tomohiro Motomura Shuji Kondo Shuhei Kanazawa Akito Sagisaka Jinglong Ma Izuru Daito Hideyuki Kotaki Hiroyuki Daido Sergei Bulanov Toyoaki Kimura Toshiki Tajima 《Optics Communications》2009,282(4):625-2346
We demonstrate a high-contrast, high-intensity double chirped-pulse amplification (CPA) Ti:sapphire laser system using an optical parametric chirped-pulse (OPCPA) pre- amplifier. By injecting cleaned microjoule seed pulses into the OPCPA, a temporal contrast greater than 1010 within picosecond times before the main femtosecond pulse is demonstrated with an output pulse energy of 1.7 J and a pulse duration of 30 fs, corresponding to a peak power of 60 TW at a 10 Hz repetition rate. This system uses a cryogenically-cooled Ti:sapphire final amplifier and generates focused peak intensities in excess of 1020 W/cm2. 相似文献
967.
Normal-phase HPLC conditions have been developed for separating the C17(3) isoprenoid isomers, which are expected to be formed as biosynthetic intermediates of chlorophyll (Chl) a, Chl a' (C13(2)-epimer of Chl a), pheophytin (Pheo) a and protochlorophyll (PChl). The application of these conditions to pigment composition analysis of greening etiolated barley leaves allowed us to detect, for the first time, the C17(3) isomers of Chl a', a possible constituent of the primary electron donor of photosystem (PS) I, P700, and those of Pheo a, the primary electron acceptor of PS II, in the very early stage of greening. The C17(3) isomer distribution patterns were approximately the same between Chl a and Chl a', but significantly different between Pheo a and Chl a', probably reflecting the similarity and difference, respectively, in the biosynthetic pathways of these pigment pairs. 相似文献
968.
D. Watanabe T. Yoshida C. Allen T. Tanabe 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(3):461-465
This work is devoted to enhance gamma-ray radiolysis of CO2 with the assistance of coexisting metal materials. It is found that lower energy electrons which are generated through interactions
of γ-photons with the coexisting metal materials and ejected to CO2 gas actually enhance decomposition of CO2 to produce CO. The increment of CO production agrees well with the increment of the deposited energy in CO2, given by the lower energy electrons emitted from the materials, which is calculated by a numerical simulations code MCNP.
It is also suggested that the volumetric decomposition of CO2 dominates the decomposition at the material’s surface. 相似文献
969.
970.
Hirobumi Shibata Masahiro Sato Satoshi Watanabe Mutsuyoshi Matsumoto 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,346(1-3):58-60
In this study, we constructed self-assembled arrays of silica particles on the micro- and nanopatterns of functionalized templates fabricated from phase-separated mixed Langmuir–Blodgett (LB) films. Electrostatic interaction between the carboxylic groups of silica particles and amino groups on the functionalized templates results in the formation of the self-assembled arrays of silica particles. The patterns of the silica particle arrays can be designed by controlling the phase-separated structures of the original mixed LB films. 相似文献