全文获取类型
收费全文 | 210篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
化学 | 121篇 |
晶体学 | 2篇 |
力学 | 4篇 |
数学 | 3篇 |
物理学 | 85篇 |
出版年
2018年 | 2篇 |
2017年 | 2篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 9篇 |
2012年 | 7篇 |
2011年 | 12篇 |
2010年 | 7篇 |
2009年 | 13篇 |
2008年 | 12篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有215条查询结果,搜索用时 15 毫秒
61.
Hisaaki Kanetsuna Masaki Hasegawa Shigenobu Mitsuhashi Toshio Kurita Kanji Sasaki Katsuhiro Maeda Hiroko Obata Tatsuko Hatakeyama 《Journal of Polymer Science.Polymer Physics》1970,8(7):1027-1037
Poly-2,5-distyrylpyrazine (poly-DSP) was investigated by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and measurements of dynamic viscoelastic and electrical properties. From DTA and TGA studies it was confirmed that poly-DSP melts at 321°C and depolymerizes rapidly to the monomer at temperatures between 335°C and 345°C in helium. The polymer is affected by oxygen above 200°C. The E′ value from dynamic viscoelasticity measurements on amorphous film is 2 × 1011 dyne/cm2 at room temperature. It decrease abruptly in the temperature range 140–150°C; but the net decrease of E′ within this temperature range is relatively small. The electrical properties of amorphous poly-DSP are characterized by a small temperature dependence of the dielectric constant between room temperature and 100°C. The dielectric loss tangent was observed to be small, and the dc conductivity was extremely small. It is concluded that rotation of the phenyl branches in the polymer occurs above ?30°C and the glass transition occurs at about 150°C. These properties are discussed in some detail in relation to the polymer structure. 相似文献
62.
Yoshio Iwakura Keisuke Kurita Fusakazu Hayano 《Journal of polymer science. Part A, Polymer chemistry》1969,7(11):3075-3087
Polythioureas having pendant hydroxyl groups were prepared by the polyaddition reaction of bisaminoalcohols and diisothiocyanates. The polythioureas had inherent viscosities in the range of 0.22–1.08 dl/g and gave transparent films by solution casting. These polythioureas were converted to polythiazolines by treatment with poly(phosphoric acid) or to poly(thiazoline–oxazolines) by treatment with a mixture of poly(phosphoric acid) and a polar solvent. 相似文献
63.
Keisuke Kurita Yasukazu Kusayama Yoshio Iwakura 《Journal of polymer science. Part A, Polymer chemistry》1977,15(9):2163-2171
Polyaddition of bisketenimines with various diamines was carried out in dioxane or toluene to afford linear polyamidines. The aliphatic diamines were fairly reactive toward the bisketenimines, and polyamidines having inherent viscosities up to 0.45 dl/g were obtained. The aromatic diamine, on the other hand, showed only poor reactivity, and the derived polyamidines had low inherent viscosities. All the polyamidines were found to be soluble in such polar solvents as dimethylacetamide and m-cresol. The thermogravimetric analysis (TGA) showed that thermooxidative decomposition started at 230–350°C. 相似文献
64.
Ohne Zusammenfassung 相似文献
65.
66.
Yoshio Iwakura Aiko Nabeya Fusakazu Hayano Keisuke Kurita 《Journal of polymer science. Part A, Polymer chemistry》1967,5(8):1865-1880
Polyurethans with chloromethyl side chains were prepared by the polyaddition reaction of bischlorohydrins and diisocyanates. The polyurethans had inherent viscosities in a range of 0.22–0.60 and gave transparent films by solution casting. These polyurethans were easily converted to the polyoxazolidones by treatment with sodium methoxide. The polyoxazolidones had inherent viscosities up to 0.51, and gave transparent films by solution casting. 相似文献
67.
M. Fujitake R. Echizenya T. Shirai S. Kurita N. Ohashi 《Journal of Molecular Spectroscopy》2004,223(2):113-119
The , , and band spectra of HCSi radical were investigated by means of near-infrared diode laser spectroscopy to determine precise molecular constants for the and states. The detailed analysis of the rotationally resolved band spectra, studied for the first time in the present investigation, leads to the precise determination of molecular constants for the state associated with the Renner-Teller interaction. We obtained −0.15126663(53) and 495.00698(30) cm−1 as the Renner-Teller parameter ε and the bending vibrational frequency ω2, respectively. Based on the molecular constants for the and states, the rotational levels of the state were analyzed to obtain molecular constants and information on upper state perturbations. Using the available spectroscopic data, valence force fields for both the and states were estimated to aid in understanding the vibrational energy levels of the HCSi radical. 相似文献
68.
In our previous work we determined that five important characteristics affect the perception of visual complexity of a texture: regularity, roughness, directionality, density, and understandability. In this paper, a set of objective methods for measuring these characteristics is proposed: regularity is estimated by an autocorrelation function; roughness is computed based on local changes; directionality is measured by the maximum line-likeness of edges in different directions; and density is calculated from the edge density. Our analysis shows a significant correlation between the objective measures and subjective evaluations. In addition, for the estimation of understandability, a new approach is proposed. We asked the respondents to name each texture, and then we sorted all these names into different types, including names that were similar. We discovered that understandability is affected by two factors of a texture: the maximum number of similar names assigned to a specific type and the total number of types. 相似文献
69.
Shunsuke Katagiri Dr. Ryota Sakamoto Hiroaki Maeda Dr. Yoshihiko Nishimori Tomochika Kurita Prof. Dr. Hiroshi Nishihara 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(16):5088-5096
This article completes our comprehensive understanding of the electron transport properties of our original π‐conjugated redox‐active molecular wires comprising Fe bridged by p‐phenylene linkers (tpy=2,2′:6′,2′′‐terpyridine). The Fe(tpy)2 oligomer wires comprise three types of tpy ligands: the anchor tpy ligand ( A series) makes a junction between the wire and electrode, the bridging bis‐tpy ligand ( L series) connects the Fe(tpy)2 units, and the terminal tpy ligand ( T series) possesses a redox site as a probe for the long‐range electron transport ability. Taking advantage of the precise tunability of the composition of the Fe(tpy)2 oligomer wires, thus far we investigated how A and L impacted on the electron‐transport ability. The excellent long‐range electron transport ability with ultrasmall attenuation constants (βd, 0.002 Å?1 as the minimum) depends on L significantly [Chem. Asian J. 2009 , 4, 1361], whereas A is unrelated to the βd value, but influences the zero‐distance electron‐transfer rate constant, ket0 [J. Am. Chem. Soc. 2010 , 132, 4524]. Herein we study the influence of terminal ligand T x (x=1–3). βd is independent of T , however, T3 , with a cyclometallated Ru complex as the redox site, gives rise to a ket0 value greater than T1 and T2 with ferrocene. This series of simple but definitive conclusions indicates that we have reached the stage of being able to precisely design molecular wires to attain desirable single‐molecule electron conduction. 相似文献
70.
Akira Okada Satoshi Yokojima Noriyuki Kurita Yasuo Sengoku Shigenori Tanaka 《Journal of Molecular Structure》2003,630(1-3):283-290
A theory for charge transfer between the electrode and the donor/acceptor molecule coupled through a DNA bridge in solution is developed. We explore the crossover between the coherent tunneling and the incoherent sequential transfer regimes by varying the electrode potential and discuss the effects of single-base mismatches in DNA duplex in both regimes. In the former regime a single-base mismatch in DNA duplex causes a reduction in the charge transfer rate simply by decreasing the electron tunneling matrix element, however, in the latter regime the effects are rather complicated. 相似文献