全文获取类型
收费全文 | 1142篇 |
免费 | 37篇 |
国内免费 | 3篇 |
专业分类
化学 | 825篇 |
晶体学 | 9篇 |
力学 | 21篇 |
数学 | 69篇 |
物理学 | 258篇 |
出版年
2022年 | 6篇 |
2021年 | 10篇 |
2019年 | 15篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 28篇 |
2015年 | 18篇 |
2014年 | 26篇 |
2013年 | 50篇 |
2012年 | 62篇 |
2011年 | 73篇 |
2010年 | 41篇 |
2009年 | 49篇 |
2008年 | 84篇 |
2007年 | 85篇 |
2006年 | 46篇 |
2005年 | 45篇 |
2004年 | 53篇 |
2003年 | 63篇 |
2002年 | 61篇 |
2001年 | 23篇 |
2000年 | 24篇 |
1999年 | 13篇 |
1998年 | 14篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 13篇 |
1993年 | 19篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1975年 | 16篇 |
1974年 | 8篇 |
1973年 | 11篇 |
1969年 | 4篇 |
1966年 | 5篇 |
排序方式: 共有1182条查询结果,搜索用时 15 毫秒
991.
Qiu Jin Takashi Yamashita Kazuyuki Horie Rikio Yokota Itaru Mita 《Journal of polymer science. Part A, Polymer chemistry》1993,31(9):2345-2351
The polyaddition reactions of alicyclic diamines such as 1,4-diaminocyclohexane (1,4-CHDA) or 4,4′-diaminodicyclohexylmethane (DCHM) and configurational isomers of 1,4-CHDA or DCHM with tetracarboxylic aromatic anhydrides in aprotic solvents were carried out to prepare high molecular weight poly(amic acid)s. Through the thermal imidization of poly(amic acid)s, several flexible polyimide films were prepared. Because of the stiffness of the alicyclic moieties in diamines, the resulting polyimides exhibit high glass transition temperatures (220–340°C) almost similar to those for corresponding aromatic polyimides which have phenylene groups in place of cyclohexyl groups, and show good thermal stability. The partial crystallization was observed for polyimides with trans-cyclohexyl moiety during the heating in differential scanning calorimetry and ascertained by wide-angle x-ray diffraction. Thus, the inhibition of the occurrence of charge transfer in polyimides is accomplished by introducing alicyclic diamines in place of aromatic diamines without reducing their thermal stability. © 1993 John Wiley & Sons, Inc. 相似文献
992.
993.
Yoshiaki Hidaka Kazuyuki Kawanami Hiroyuki Kawano Masao Suga 《Chemical physics letters》1984,103(5):393-396
CF3ClH2 mixtures highly diluted with Ar were heated to 1400–1600 K behind reflected shock waves. The HCl emission was followed in order to determine the rate constant (k1) of the reaction, CF3Cl + M CF3 + Cl + M, and k1 = 2.1 × 1017 exp(?75000/RT) cm3 mol?1 s?1 was computed. 相似文献
994.
995.
996.
Reductive deiminations of diaryl sulfilimides and dialkyl and aryl alkyl sulfoximides with p-toluenesulfonyl nitrite, a new nitrosating reagent, has been investigated. 相似文献
997.
T. Idehara I. Ogawa K. Kawahata H. Iguchi K. Matsuoka 《International Journal of Infrared and Millimeter Waves》2004,25(11):1567-1579
Gyrotron FU II has been successfully applied as a submillimeter wave radiation source to plasma scattering measurements on the Compact Helical System (CHS) in National Institute for Fusion Science (NIFS) in Japan. The gyrotron operates in a long pulse mode (the pulse width is about 600 ms) at a frequency of about 350 GHz (the corresponding wavelength is 0.85 mm). The output power is about 110 W. The output power is transmitted along a circular waveguide system and converted to a Gaussian-like beam by a quasi-optical antenna. After that, the beam is directed onto the CHS plasma and the scattered signal is detected by a homodyne detection system. The frequency and the wave number of the scattered signal are analyzed. The results suggest that a broad band low frequency (several tens to several hundreds kHz) density fluctuation is excited in the CHS plasma only during neutral beam injection (NBI) or ion cyclotron resonance (ICR) heating. 相似文献
998.
999.
33S-nuclear hyperfine structure has been analyzed in the ESR spectrum of the disulphide anion in γ-irradiated L-cystine dihydrochloride. The results have confirmed that the unpaired electron occupies an antibonding signa-type orbital consisting essentially of sulphur 3p orbitals. 相似文献
1000.
The title compound, [Fe(tz)6][Fe2OCl6] (1) (tz = thiazole) has been synthesized under argon by the reaction of anhydrous FeCl3 with thiazole in ethanol. 1 crystallises in the cubic space group
(no. 205) with a = 15.001(5) Å, V = 3375(2) Å3, Z = 4, R = 0.061 and Rw = 0.073. 1 consists of a face-centered cubic array of [Fe(tz)6]2 cations, with the oxo-bridged [Fe2OCl6]2− anion occupying the cell and edge centres. 相似文献