全文获取类型
收费全文 | 1255篇 |
免费 | 20篇 |
国内免费 | 3篇 |
专业分类
化学 | 981篇 |
晶体学 | 12篇 |
力学 | 10篇 |
数学 | 75篇 |
物理学 | 200篇 |
出版年
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 16篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 18篇 |
2015年 | 13篇 |
2014年 | 11篇 |
2013年 | 44篇 |
2012年 | 44篇 |
2011年 | 59篇 |
2010年 | 37篇 |
2009年 | 41篇 |
2008年 | 83篇 |
2007年 | 61篇 |
2006年 | 66篇 |
2005年 | 79篇 |
2004年 | 66篇 |
2003年 | 61篇 |
2002年 | 58篇 |
2001年 | 36篇 |
2000年 | 40篇 |
1999年 | 25篇 |
1998年 | 16篇 |
1997年 | 15篇 |
1996年 | 16篇 |
1995年 | 13篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 20篇 |
1984年 | 33篇 |
1983年 | 12篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 15篇 |
1978年 | 14篇 |
1977年 | 17篇 |
1976年 | 12篇 |
1975年 | 11篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1969年 | 6篇 |
1968年 | 6篇 |
排序方式: 共有1278条查询结果,搜索用时 640 毫秒
121.
122.
Kensuke Okusa Yuki Suita Yukio Otsuka Mineo Tahara Tohru Ikegami Nobuo Tanaka Masayoshi Ohira Masakazu Takahashi 《Journal of separation science》2010,33(3):348-358
The effectiveness of several basic compounds for testing silica‐based stationary phases was reviewed by applying them to recent columns for reversed‐phase HPLC. Most octadecylsilylated (C18) stationary phases, prepared as a base‐deactivated material from high‐purity silica gel with endcapping, provided excellent peak shape and column efficiency for the bases including benzylamine and amitriptyline that once caused problems and were subsequently employed for testing silanol activities. However, a cyclic tertiary amine, dextrometorphan, was eluted as an acceptable peak from only a few columns at neutral pH. Such a more sensitive probe is expected to contribute to further improvement of the stationary phase for reversed‐phase HPLC. 相似文献
123.
Mizoshita N Yamanaka K Shimada T Tani T Inagaki S 《Chemical communications (Cambridge, England)》2010,46(48):9235-9237
Polycondensation of 9-mesityl-10-methylacridinium-bridged organosilane in the presence of a nonionic surfactant yielded a mesostructured organosilica solid with a functional framework that exhibited long-lived photoinduced charge separation. 相似文献
124.
Masahiro Uchida Toshiyuki Suda Toshiro Fujimori Tadashi Fujii Tetsuhiko Inagaki 《Proceedings of the Combustion Institute》2011,33(2):2327-2333
Detonation experiments are conducted to investigate the detonation wave behavior in steam pipelines of boiling water reactors. Accumulated gases in BWRs are stoichiometric hydrogen/oxygen mixtures diluted with steam at 7 MPa. In the experiment, flammable gas mixture diluted with nitrogen at room temperature and up to 5 MPa is used to achieve equivalent detonation condition. Two test pieces are used, one is straight tube and the other is 90-degree bend. No initial pressure dependency in detonation wave behavior is observed in the experiments. However, in the straight tube tests, detonation velocities higher than theoretical values are measured when the initial pressures are greater than 2.3 MPa. This result is considered as attribution of real gas effect. In the 90-degree bend experiments, pressure time histories reveal pressure loads greater than the straight tube portion at two locations. One is a high pressure peak at the extrados of the bend and the other is a double pressure peak just downstream of the bend outlet. Second pressure peak just downstream of the bend outlet is due to transverse wave propagation. Additionally, the largest impulse is observed not at the extrados of the bend but at the intrados of bend outlet. These results show the importance of more investigations on transverse wave behaviors in failure potential evaluation. 相似文献
125.
126.
127.
128.
129.
Nobuo Ogata Teruaki Yanagawa Koukichi Yoshida 《Journal of Polymer Science.Polymer Physics》1986,24(9):1917-1929
Fracture mechanics was used to investigate the environmental stress cracking (ESC) of low density polyethylene (LDPE). Annealed and quenched samples were prepared; a single edge notch was made and the samples were fractured under constant load in a liquid methanol environment. The relation between the stress intensity factor K and the crack speed ? has been investigated. There is a large difference between annealed and quenched samples in the variation of this relation with temperature and applied load. The cause of this difference is discussed in detail. We propose that thermally activated molecular motion is essential to ESC of the annealed LDPE while stress concentration contributes markedly to ESC of the quenched LDPE. 相似文献
130.
Highly efficient processes for fine particle formation of metal alloys and metal oxides were developed using a high-power laser. In these processes, laser light was used only for the ignition of a thermal chain reaction. This reaction was suppressed by adding inert gases, and the suppression effect was in the order C3H8 > C2H6 > CH4 > He > Ar > Xe. Oxygen accelerated the reaction because of the large exothermicity of the reaction of oxygen with methyl metal compounds. 相似文献