全文获取类型
收费全文 | 270篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
化学 | 259篇 |
晶体学 | 7篇 |
物理学 | 10篇 |
出版年
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 6篇 |
2011年 | 8篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 12篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 15篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 8篇 |
1978年 | 15篇 |
1977年 | 9篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 6篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1968年 | 5篇 |
1967年 | 10篇 |
1966年 | 2篇 |
排序方式: 共有276条查询结果,搜索用时 31 毫秒
31.
Kenji Yamamoto Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》1974,12(3):613-626
Ring-substituted phenyl propenyl ethers were found to form homopolymers without any rearrangement by metal halides. Phenyl propenyl ethers were less reactive than the corresponding phenyl vinyl ethers in cationic polymerization. In order to study the electronic effect of a substituent on the reactivity, cis-p-Cl,p-CH3, and p-CH3O-phenyl propenyl ethers were copolymerized with phenyl propenyl ether in methylene chloride at ?78°C with stannic chloride–trichloroacetic acid, and their 1H- and 13C-NMR spectra were measured. The reaction constant ρ against Hammett σp was ?2.1. The cis-phenyl propenyl ethers were slightly more reactive than the corresponding trans isomers. On the other hand, an o-methyl group decreased the reactivity of phenyl propenyl ether. The low reactivity of o-methyl phenyl propenyl ether was attributed to the steric hindrance between the propagating carbocation and the monomer. 相似文献
32.
This paper focuses on two recent topics in living cationic polymerization of vinyl monomers, i.e., (a) Development of new initiating systems: RCOOH/Lewis acid for vinyl ethers; CH3CH(C6H5)Cl/SnCl4/nBu4NCl for styrene. (b) Synthesis of shape-controlled poly(vinyl ethers): Tri-armed star polymers; Multi-armed spherical polymers. For the RCOOH-based systems, a generalized concept of living cationic polymerization was discussed on the basis of the effects of the counteranions (or R) and Lewis acids (ZnCl2 and EtAlCl2). The CH3CH(C6H5)Cl-based system permitted a truly living cationic polymerization of styrene. The tri- and multi-armed poly(vinyl ethers) included new amphiphilic polymers of unique topology, solubility, etc., all of which were prepared by living cationic polymerization. 相似文献
33.
34.
Toshinobu?YogoEmail author Reimon?Fukuzawa Wataru?Sakamoto Shin-ichi?Hirano 《Journal of nanoparticle research》2005,7(6):633-640
Nanocrystalline BaTiO3 particles modified with polarizable ligands were synthesized through hydrolysis of modified metal–organics below 100°C. BaTiO3 precursor was synthesized from barium metal, titanium isopropoxide and polarizable ligands in a mixture of ethanol and 2-ethoxyethanol.
The modified Ba–Ti complex alkoxide was hydrolyzed yielding BaTiO3 particles modified with organics. The crystallinty of nanometer-sized particles was dependent upon the hydrolysis conditions,
and increased with increasing water amount and time. The nanocrystalline particles were identified to be BaTiO3 by X-ray diffraction (XRD) and electron diffraction. A fluid consisting of modified BaTiO3 particles and silicone oil revealed a typical electrorheological (ER) behavior on applying DC field. The ER behavior was
found to depend upon the kind of ligand. 4-Fluorobenzyloxy modifier revealed the highest yield stress in the ER measurement
among 4-substitued benzyloxy ligands examined. 相似文献
35.
Toshinobu Kanai Hiroki Ishibashi. Yoshikazu Hayashi Kunio Oka Takaaki Dohmaru Tatsuo Ogawa Shoji Furukawa Robert West 《Journal of Polymer Science.Polymer Physics》2001,39(11):1085-1092
The thermochromic behavior of poly(di‐n‐octylsilane) {[Si(C8H17)2]n; PDOS} was studied by ultraviolet (UV) absorption, differential scanning calorimetry, and X‐ray diffraction measurements. The structure of PDOS in the low‐temperature phase strongly depended on not only the temperature but also the rate of cooling, that is, the thermal history. Temperature‐dependent UV absorption spectra were highly dependent on thermal hysteresis. Cooled rapidly (10 K/min), PDOS showed two absorption peaks at 3.32 and 3.51 eV in low‐temperature‐ordered phases, whereas a single absorption peak at 3.32 eV became predominant with slow cooling (0.3 K/min). The appearance of the two peaks at low temperatures suggested that a mixture of different conformations was introduced by rapid cooling. A fiber diffraction pattern measured at 240 K after rapid cooling also showed evidence of the existence of novel conformation. A temperature‐dependent powder X‐ray diffraction pattern changed significantly between 270 and 280 K. Rapid cooling reduced the intensity of the X‐ray diffraction peak in this temperature region. This intensity change was explained by the conformational mixture in the polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1085–1092, 2001 相似文献
36.
Hiroshi Onizuka Masaki Kato Tetsuo Shimura Wataru Sakamoto Toshinobu Yogo 《Journal of Sol-Gel Science and Technology》2008,46(1):107-115
Proton conductive inorganic–organic hybrid membranes were synthesized from dimethylethoxyvinylsilane (DMEVS), vinylphosphonic
acid (VPA) and 3-glycidoxypropyltrimethoxysilane (GPTMS) through copolymerization followed by sol–gel process. The ratio of
phosphorus to silicon in the copolymer almost corresponded to the charged molar ratio of VPA to DMEVS when the ratio of VPA
to DMEVS was below 1/2. Self-standing, homogeneous, highly transparent membranes were synthesized from DMEVS–VPA copolymer
and GPTMS via sol–gel condensation. Differential thermal analysis-thermogravimetry analyses indicated that these membranes
were thermally stable up to 200 °C. The results of Fourier transform infrared and 13C NMR revealed that phosphonic acid groups of VPA were chemically bound to organosiloxane network. The copolymerization and
condensation of (DMEVS–VPA)/GPTMS were confirmed by 31P and 29Si NMR spectra. The proton conductivity of the hybrid membranes increased with phosphonic acid content. The membrane of (DMEVS–VPA)/GPTMS
showed a remarkable conductivity of 6.3 × 10−2 S cm−1 at 130 °C and 100% relative humidity. 相似文献
37.
Masai H Fujiwara T Matsumoto S Takahashi Y Iwasaki K Tokuda Y Yoko T 《Optics letters》2011,36(15):2868-2870
The authors have demonstrated white light emission of rare earth (RE)-free Mn-doped SnO-ZnO-P(2)O(5) glass. The RE-free glass shows white light emission with a high value of quantum efficiency (QE) comparable to conventional crystalline phosphor. It is notable that the high QE value is attained for RE-free transparent glass, and the broad emission can be continuously tuned by both the amount of activator and the composition of the glass. Since this glass possesses low-melting property, we emphasize that the glass phosphor will lead to the development of a novel inorganic white-light-emitting device in combination with a solid state UV light-emitting source. 相似文献
38.
Shigeki Habaue Soichiro Murakami Hideyuki Higashimura 《Journal of polymer science. Part A, Polymer chemistry》2005,43(23):5872-5878
Novel oxovanadium(IV)–bisoxazoline catalysts, such as vanadyl sulfate (VOSO4)–(R)‐2,2′‐isopropylidenebis(4‐phenyl‐2‐oxazoline) [(R)Phbox], for the asymmetric oxidative coupling polymerization (AOCP) of 2,3‐dihydroxynaphthalene were developed. For example, the AOCP with VOSO4–(R)Phbox in CH2Cl2–MeOH [7/1 (v/v)] at room temperature for 24 h under an O2 atmosphere, followed by acetylation of the hydroxyl groups, afforded a polymer in a 58% yield with a specific rotation of [α]D = ?147. The enantioselectivity during the polymerization was estimated to be 80% enantiomeric excess (S), a value much higher than that observed for the polymerizations with the copper(I)‐based catalyst systems and the typical oxovanadium(IV) catalysts reported for the asymmetric oxidative coupling producing the 1,1′‐bi‐2‐naphthol derivatives. © 2005 Wiley Periodicals, Inc., Inc. J Polym Sci Part A: Polym Chem 43: 5872–5878, 2005 相似文献
39.
40.
Moriya M Kato D Sakamoto W Yogo T 《Chemical communications (Cambridge, England)》2011,47(22):6311-6313
Plastic crystallinity of lithium salt, [LiB(OCH(2)CH(2)OCH(3))(4)] (1), and its solid-state ionic conductivity are disclosed. The addition of small amounts of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to borate 1 led to the drastic increase of the ionic conductivity and lithium transport number of the electrolyte. 相似文献