全文获取类型
收费全文 | 1034篇 |
免费 | 40篇 |
国内免费 | 4篇 |
专业分类
化学 | 790篇 |
晶体学 | 9篇 |
力学 | 6篇 |
数学 | 66篇 |
物理学 | 207篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 10篇 |
2019年 | 16篇 |
2018年 | 6篇 |
2016年 | 20篇 |
2015年 | 19篇 |
2014年 | 24篇 |
2013年 | 52篇 |
2012年 | 61篇 |
2011年 | 60篇 |
2010年 | 42篇 |
2009年 | 40篇 |
2008年 | 48篇 |
2007年 | 61篇 |
2006年 | 78篇 |
2005年 | 49篇 |
2004年 | 53篇 |
2003年 | 39篇 |
2002年 | 42篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 19篇 |
1998年 | 16篇 |
1997年 | 16篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 20篇 |
1991年 | 16篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 19篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1972年 | 5篇 |
1967年 | 5篇 |
排序方式: 共有1078条查询结果,搜索用时 15 毫秒
1.
2.
Motohiro Mizuno Yoji Aoki Darius Greenidge 《Journal of Physics and Chemistry of Solids》2006,67(4):705-709
The angular dependence of the 27Al NMR spectrum was measured for single crystals of smoky and colorless topaz, Al2SiO4(F,OH)2. Smoky topaz was obtained by irradiating high energy neutrons to colorless topaz. The quadrupole coupling constant e2Qq/h and the asymmetry parameter η were obtained from the analysis of the angular dependences of quadrupole splitting of the 27Al NMR spectrum. The local structures around the aluminum atoms in smoky and colorless topaz were discussed from the magnitude and the direction of the electric field gradient. The directions of principal axes of the EFG tensor of 27Al were close to the directions of Al-O and Al-F bonds. The difference in the bond lengths between Al(1)-F(1) and Al(1)-F(2) was found to affect the x and y components of the EFG tensor. 相似文献
3.
Tomohiro Kyotani Sonoko Kakui Takehito Mizuno Naoto Shimotsuma Soushi Inoue Junji Saito 《Analytical sciences》2006,22(7):1031-1034
A zeolite NaA (LTA) membrane supported by an alumina porous support tube for pervaporation (PV) dehydration of ethanol was characterized by transmission electron microscopy (TEM) using a focused ion beam (FIB) thin-layer specimen preparation technique and by Fourier transform infrared attenuated total reflectance method (FTIR-ATR) using a diamond prism as the waveguide. FIB-TEM clearly presented cross-section images up to about 15 microm depth from the membrane surface. FTIR-ATR monitored the Si-O asymmetric stretching vibration spectrum. The Si-O spectrum was compared with the TEM image and their relationships were discussed. By combining the two methods, we could study the thickness of surface LTA crystals, the grain boundary, the LTA/alumina interface structure and the crystallinity and density of materials inside of the alumina porous support. Consequently, fine structure changes of the LTA membrane corresponding to the hydrothermal synthesis condition could be sensitively detected. 相似文献
4.
This paper presents a simple chaotic circuit consisting of two capacitors, one linear two-port VCCS and one time-state-controlled
impulsive switch. The impulsive switch causes rich chaotic and periodic behavior. The circuit dynamics can be simplified into
a one-dimensional return map that is piecewise linear and piecewise monotone. Using the return map, we clarify parameter conditions
for existence of chaotic and periodic attractors and coexistence state of attractors. 相似文献
5.
Three protocols for shotgun process are put forth in which simultaneous multi-fold reactions occur exclusively to each other. The first one involves simple combination of selective and non-selective reactions. Even if the simple protocol fails to give rise to the high selectivity, satisfactory outcome can be achieved by kinetic control or adjustment of functional groups. 相似文献
6.
K. M. A. Salam Hidekazu Konishi Masahiro Mizuno Hisashi Fukuda Shigeru Nomura 《Applied Surface Science》2002,190(1-4):88-95
Polycrystalline (1−x)Ta2O5−xTiO2 thin films were formed on Si by metalorganic decomposition (MOD) and annealed at various temperatures. As-deposited films were in the amorphous state and were completely transformed to crystalline after annealing above 600 °C. During crystallization, a thin interfacial SiO2 layer was formed at the (1−x)Ta2O5−xTiO2/Si interface. Thin films with 0.92Ta2O5–0.08TiO2 composition exhibited superior insulating properties. The measured dielectric constant and dissipation factor at 1 MHz were 9 and 0.015, respectively, for films annealed at 900 °C. The interface trap density was 2.5×1011 cm−2 eV−1, and flatband voltage was −0.38 V. A charge storage density of 22.8 fC/μm2 was obtained at an applied electric field of 3 MV/cm. The leakage current density was lower than 4×10−9 A/cm2 up to an applied electric field of 6 MV/cm. 相似文献
7.
Tomoji Kumano Yoshifumi Ohata Norikazu Fujii Yoshiyuki Ushigami Tetsuro Takeshita 《Journal of magnetism and magnetic materials》2006
All kinds of high-permeability GO are manufactured using AlN as the main inhibitor. From a purely metallurgical viewpoint, three types of inhibitor preparation for high-permeability GO have been shown. They include a complete solution without nitriding, a complete precipitation with nitriding and a partial precipitation with nitriding. In this study, another possibility, i.e., a complete solution method with nitriding, was investigated to avoid the extra high-temperature slab reheating and to examine the effect of nitriding on GO bearing Al. This method can also provide the sharp Goss texture, and nitriding is shown to be very useful for changing the inhibitor intensity, depending on the primary grain size. 相似文献
8.
9.
Calcium-induced alginate gel beads (Alg-Ca) containing various polysaccharides, including an alginate hydrolysate, were prepared and the drug release profiles were investigated. Hydrocortisone (HC) was gradually released from Alg-Ca into the mimic gastric fluid, while in intestinal fluid, it was quickly released with the dissolution of Alg-Ca. However, with Alg-Ca containing 5% chitin (CT), dissolution of Alg-Ca was not observed, and release of HC showed apparent zero-order kinetics. Furthermore, addition of the alginate hydrolysate altered the HC-release profile for Alg-Ca. 相似文献
10.