全文获取类型
收费全文 | 2832篇 |
免费 | 82篇 |
国内免费 | 12篇 |
专业分类
化学 | 2214篇 |
晶体学 | 38篇 |
力学 | 24篇 |
数学 | 49篇 |
物理学 | 601篇 |
出版年
2022年 | 15篇 |
2021年 | 24篇 |
2020年 | 20篇 |
2019年 | 30篇 |
2018年 | 16篇 |
2017年 | 22篇 |
2016年 | 46篇 |
2015年 | 45篇 |
2014年 | 47篇 |
2013年 | 95篇 |
2012年 | 149篇 |
2011年 | 178篇 |
2010年 | 90篇 |
2009年 | 96篇 |
2008年 | 156篇 |
2007年 | 168篇 |
2006年 | 148篇 |
2005年 | 163篇 |
2004年 | 142篇 |
2003年 | 127篇 |
2002年 | 98篇 |
2001年 | 102篇 |
2000年 | 75篇 |
1999年 | 67篇 |
1998年 | 33篇 |
1997年 | 38篇 |
1996年 | 32篇 |
1995年 | 30篇 |
1994年 | 25篇 |
1993年 | 27篇 |
1992年 | 40篇 |
1991年 | 31篇 |
1990年 | 37篇 |
1989年 | 27篇 |
1988年 | 17篇 |
1987年 | 35篇 |
1986年 | 18篇 |
1985年 | 32篇 |
1984年 | 33篇 |
1983年 | 19篇 |
1982年 | 33篇 |
1981年 | 31篇 |
1980年 | 22篇 |
1979年 | 41篇 |
1978年 | 23篇 |
1977年 | 20篇 |
1976年 | 15篇 |
1975年 | 17篇 |
1974年 | 19篇 |
1973年 | 15篇 |
排序方式: 共有2926条查询结果,搜索用时 0 毫秒
101.
A hydrothermal process of precipitating iron sulfide gives rise to greigite (space group: Fd3m), pyrite (Pa3), mackinawite (P4/nmm) and pyrrhotite (P6/mmc), as the case may be. Greigite blended with pyrite is formed, when the autoclave for the hydrothermal process is cooled down not rapidly, but slowly from 192°C to room temperature. Greigite and pyrite here form partially a solid solution. A mechanical mixture of greigite-mackinawite and that of greigite-pyrrhotite appear in the hydrothermal process above and below 192°C, respectively. Pure greigite is produced only by rapid quenching of the reaction tube from 192°C, to 10°C. 相似文献
102.
H. Okamoto K. Yamaguchi M. Haraguchi T. Okamoto 《Applied physics. B, Lasers and optics》2012,108(1):149-152
We fabricated and investigated a plasmonic racetrack resonator with a trench structure. Trench channel plasmon polaritons excited by end-fire coupling at a wavelength of 633 nm are observed in the fabricated racetrack resonator. The racetrack resonator also worked as a plasmonic racetrack resonator. The experimental and simulation results of the electric field distributions are in good agreement. 相似文献
103.
104.
Koichiro Shirota Ichirou Yamaguchi Kiyoshi Kanie Tomiki Ikeda Tamejiro Hiyama Ichiro Kobayashi 《Liquid crystals》2013,40(5):555-558
The optical properties of two kinds of photochromic antiferroelectric liquid crystal (AFLC) containing an azo group have been examined. Depending on the substituting group at the chiral centre, these AFLCs showed different photoinduced phase transitions by Ar+ laser light irradiation. This phase transition has led to a new form of optical switching controlled by a bias voltage. In addition, it was found that these AFLCs caused an azimuthal photoalignment effect regulated by linearly polarized Ar+ laser light irradiation. These phenomena were applied to image storage. 相似文献
105.
Shoichi Kutsumizu Koushi Morita Tatsuya Ichikawa Shinichi Yano Shuichi Nojima Takanari Yamaguchi 《Liquid crystals》2013,40(11):1447-1458
The structure of the thermotropic cubic phases of 4′- n -alkoxy-3′-nitrobiphenyl-4-carboxylic acids (ANBC- n , where n indicates the number of carbon atoms in the alkoxy group) was studied by X-ray diffraction. For the homologues with n = 15, 16, 17, and 18, the cubic phase was of an Ia 3 d type, whereas the homologues with n = 19, 20, and 21 exhibited an Im 3 m cubic structure; for these seven homologues the same type of cubic structure was observed both on heating and cooling. Further lengthening of the alkoxy chain to n = 22 and 26, however, gave two types of cubic structure in the cubic phase region on heating, one with Im 3 m symmetry in the low temperature region and the other with Ia 3 d symmetry in the high temperature region. On cooling, the two homologues exhibited the Ia 3 d cubic structure only. This is the first example in the cubic phase region of a series of homologues containing two types of structure, dependent on temperature and n . Such a complicated phase diagram in the cubic region is clearly understood qualitatively in terms of Gibbs free energy-temperature diagrams. The dependence of structural parameters such as the cubic lattice constant on the alkoxy chain length n are also presented and discussed. 相似文献
106.
107.
Seiichi Ohta Susumu Inasawa Yukio Yamaguchi 《Journal of Polymer Science.Polymer Physics》2012,50(12):863-869
When a mixture of liquid crystal (LC) and photo reactive monomer is irradiated by UV light, polymerization occurs and LC droplets form through phase separation, producing polymer dispersed LCs (PDLCs). Although size control of LC droplets and reduced amounts of LC in PDLC films are important in applications, precise size control of LC droplets at a low LC fraction has not yet been accomplished. In this study, the phase diagrams of the LC/initial monomer and the LC/polymer during polymerization were used to control LC droplet size at various LC fractions. Both the relative position of the sample in the initial phase diagram and the shift of the phase separation line during polymerization were shown to be important in determining the size of LC droplets. Our results are expected to provide a new strategy for precise size control of LC droplets especially at a low LC fraction range, which would be a great help for PDLC applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
108.
109.
The effect of the dilution of silane and nitrogen with hydrogen on the optical properties of hydrogenated amorphous silicon-nitrogen films prepared by plasma deposition has been investigated as functions of the gas-volume ratio γ (= ([SiH4] + [N2])/([SiH4] + [N2] + [H2]) and the substrate temperature. The prepared films are characterized by the values of the deposition rate, the optical gap, the Urbach energy, the defect density, the integrated infrared absorption intensity and the refractive index, and by correlations between these parameters and the type of hydrogen- and nitrogen-bonding configurations estimated from infrared absorption spectra. The hydrogen dilution effect is discussed in terms of the above and compared with that in hydrogenated amorphous silicon reported in a previous paper by the present authors. It is pointed out that nitrogen atoms incorporated into the silicon network cause more disorder than incorporated hydrogen atoms, from the γ dependence of the Urbach energy and the integrated infrared intensities associated with the hydrogen and nitrogen bondings. 相似文献
110.