全文获取类型
收费全文 | 193篇 |
免费 | 2篇 |
国内免费 | 9篇 |
专业分类
化学 | 147篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 15篇 |
物理学 | 38篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 20篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 9篇 |
2009年 | 9篇 |
2008年 | 14篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 9篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有204条查询结果,搜索用时 31 毫秒
101.
The extraordinary mechanical and swelling/deswelling properties of nanocomposite (NC) gels are attributed to their unique organic (polymer)/inorganic (clay) network structure. In this study, poly(N‐isopropylacrylamide) (PNIPA) was successfully separated from an NC gel network by decomposing the clay (hectorite) using hydrofluoric acid (HF). A very low HF concentration (0.2 wt.‐%) was adequate for the decomposition of the clay without causing any damage to PNIPA. The separated PNIPA had a high (=5.5 × 106 g · mol−1). Also, was almost constant regardless of the clay concentration (Cclay = 1–25 × 10−2 mol · l−1), even though the properties of the NC gel varied widely over this Cclay range. Comparisons of NC gels, PNIPA, and SiO2‐NC gels indicated that the clay platelets specifically play an important role in NC gels.
102.
103.
Kentaro Takahama Asami Takada Shota Tada Mai Shimizu Kazutoshi Sayama Riki Kurokawa Takanori Oyoshi 《Chemistry & biology》2013,20(3):341-350
Highlights? TLS/FUS is identified as a G-quadruplex telomere DNA and TERRA-binding protein ? TLS binds to G-quadruplex telomere DNA and TERRA simultaneously ? The cells overexpressing TLS show gradual and progressive telomere shortening ? Overexpression of TLS results in trimethylation of histone H3 and H4 at telomere 相似文献
104.
Ryoji Sugimura Shuichi Suzuki Masatoshi Kozaki Kazutoshi Keyaki Koichi Nozaki Hironori Matsushita Noriaki Ikeda Keiji Okada 《Research on Chemical Intermediates》2013,39(1):185-204
Two triads (i.e., 3PTZ–Pt–MNDI and 10PTZ–Pt–MNDI) consisting of 3-phenothiazine (3PTZ) or 10-phenothiazine (10PTZ), bipyridine–diacetylide platinum complex (Pt), and naphthalene diimide (MNDI) chromophores linked by highly twisted biphenylene spacers have been prepared. The formation and decay of the charge-separated (CS) states in toluene were studied by use of picosecond and nanosecond laser photolysis via selective excitation of the Pt moiety. The time required for formation of the CS state, PTZ+–Pt–MNDI?, from PTZ–3Pt*–MNDI was determined to be τ CS = 280 ps for 3PTZ+–Pt–MNDI? and τ CS = 230 ps for 10PTZ+–Pt–MNDI?. The lifetimes of the CS states were determined to be τ CR1 = 75 ns (95 %) and τ CR2 = 285 ns (5 %) for 3PTZ+–Pt–MNDI? and τ CR = 830 ns for 10PTZ+–Pt–MNDI?. Formation and decay of the CS states are discussed in terms the Marcus theory and the spin-correlated radical pair mechanism. 相似文献
105.
106.
A series of liquid crystalline 2,3-bis(trifluoromethyl)phenyl derivatives has been synthesized and their physical properties, namely the dielectric anisotropy, the birefringence, the rotational viscosity and the phase sequences have been measured. This novel class of compound showed an extremely large negative dielectric anisotropy (-6.1 to-11.4), exceeding that of currently used 2,3-difluorophenyl derivatives. On the other hand, the compounds synthesized were found to have poorer mesogenic potential and larger viscosities than those of the 2,3-difluorophenyl derivatives. Molecular modelling using molecular orbital calculations has been performed and the calculation results have been compared with experimentally evaluated physical properties. 相似文献
107.
108.
Kazutoshi Iwamoto Yukio Ohnuki Kiyoshi Sawada Manabu Senō 《Molecular Crystals and Liquid Crystals》2013,570(1-2):95-103
Transition properties of some compounds of the type, n-C n H2n+1N+(CH3)3X-, with n = 10, 12, 14, 18, 22, and X = Cl, Br, and I, were investigated. All these compounds show a solid-solid phase transition with a large enthalpy change in the range of temperature 350 ~ 400K. The transition behaviors were investigated by the aid of DSC, TG, X-ray, and optical microscope. The solid-solid phase transition is regarded to be caused by melting of the layer of hydrocarbon chains of the compounds, while the rigid ionic layer retains the regular arrangement. Some relationships between the physical properties and the structure of the compounds are discussed. 相似文献
109.
Takehiro Yoshida Yuichi Oshima Takeshi Eri Ken Ikeda Shunsuke Yamamoto Kazutoshi Watanabe Masatomo Shibata Tomoyoshi Mishima 《Journal of Crystal Growth》2008,310(1):5-7
By using the hydride vapor phase epitaxy and a void-assisted separation method, freestanding 3-in GaN substrates were successfully fabricated for the first time, and the process showed an excellent reproducibility. A thick GaN layer 3.2 in in diameter was easily separated from the base substrate. No cracks were generated during the separation process. The dislocation density was of the order of 106 cm–2. The carrier density was approximately 1×1018 cm–3 and the mobility was 3.4×102 cm2 V–1 s–1. The concentrations of impurities, estimated by secondary-ion mass spectrometry, were below the limit of detection, except for Si. The Si concentration was approximately 1×1018 cm–3, which is in good agreement with the carrier density. 相似文献
110.
Here, a simple new method is proposed to evaluate water for the presence of pesticides. Specifically, pesticides for golf link maintenance were used as the targets for this investigation. Water samples containing the pesticides were mixed with particulate adsorbent, after which the pesticides were extracted from the adsorbents using supercritical fluid carbon dioxide and then analyzed by gas chromatography-mass spectrometry. The recoveries of pesticides were examined with several types of adsorbents and found to be related to their octanol/water partition coefficients (Kow) for most of the adsorbents. Good recoveries were obtained when the water samples were mixed with octadecylsilane (ODS) and stylene-divinylbenzene copolymer (XAD) resins for 15 and 30 min, respectively. In the supercritical fluid extraction, extraction pressure affected the efficiency of extraction from XAD while a little effect on extraction from ODS, probably due to the internal structure of the adsorbents. The limit of detection ranged from 0.002 to 2.3 μg L−1 and the method is suitable for the measurement of golf link pesticides in μg L−1 order to 100 μg L−1. The procedure of the proposed method was simpler than the conventional solid-phase extraction method. Finally, the method presented here was used to identify pesticides present in actual wastewater from golf links. 相似文献