全文获取类型
收费全文 | 363篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
化学 | 227篇 |
晶体学 | 3篇 |
力学 | 12篇 |
数学 | 30篇 |
物理学 | 97篇 |
出版年
2023年 | 3篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 14篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 14篇 |
2009年 | 8篇 |
2008年 | 30篇 |
2007年 | 26篇 |
2006年 | 21篇 |
2005年 | 31篇 |
2004年 | 24篇 |
2003年 | 16篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有369条查询结果,搜索用时 0 毫秒
151.
Chizu Sekine Kazunori Iwakura Naoto Konya Masayoshi Minai Koichi Fujisawa 《Liquid crystals》2013,40(9):1375-1387
We have synthesized and investigated new 3-ring phenylacetylene liquid crystals with high birefringence values (Δn) to improve the nematic temperature range while retaining a high optical anisotropy. In the case of modifying the terminal ring, the introduction of branched alkoxy chains, fluorine or methyl groups shifted the nematic phase to lower temperatures. In order to minimize the influence of the substituent on Δn, the incorporation of lateral methyl groups was chosen as the most profitable method for obtaining wide and low temperature nematic phases. With these results in mind, we studied the effect of the position of the methyl group on the physical properties. The most effective methyl position for improving the nematic temperature range was on the central ring. From the standpoint of obtaining high Δn values and low viscosity, the central ring was also the best position. 相似文献
152.
Yoshitaro Miyashita Nagina Mahboob Satoko Tsuboi Yasunori Yamada Kiyoshi Fujisawa Ken‐ichi Okamoto 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):558-559
The Re atom in [Re(C9H6N2)Cl3(C18H15P)] is octahedrally coordinated by three Cl atoms in facial positions, two N atoms from 8‐imidoquinoline (imq) and one P atom from triphenylphosphine. The Re—N(imido) distance [1.760 (9) and 1.772 (8) Å] for imq is very short and implies double‐bond character. The trans influence of the P atom is indicated. Intra‐ and intermolecular π–π interactions between the π‐rings in the complex are also observed. 相似文献
153.
Our research group has developed an ultra slim and bendable backlight system, which was manufactured by a continuous roll-to-roll
process, with a unified component for liquid crystal display (LCD). This backlight system, which has a thickness of 0.26 mm,
is simply composed of a light guide film and an optically patterned film made of photocurable resin with micro particles,
consequently it does not require any additional optical films such as prism sheets or diffuser. In addition, we have developed
a new light guide component which is composed of bundled optical fibers in order to collimate light from the light source
to the light guide film. We found that the backlight system could be radiated uniformly across the LCD surface whether plane
or curved, and we were able to realize an advanced LCD with good flexibility, high efficiency and high productivity. 相似文献
154.
A novel design is described for an amperometric biosensor based on NAD(P)-dependent glucose dehydrogenase (GDH) combined with a plasma-polymerized thin film (PPF). The GDH is sandwiched between several nanometer thick acetonitrile PPFs on a sputtered gold electrode (PPF/GDH/PPF/Au). The lower PPF layer plays the role as an interface between enzyme and electrode because it is extremely thin, adheres well to the substrate (electrode), has a flat surface and a highly-crosslinked network structure, and is hydrophilic in nature. The upper PPF layer (overcoating) was directly deposited on immobilized GDH. The optimized amperometric biosensor characteristics covered 2.5-26 mM glucose concentration at +0.6 V of applied potential; the least-squares slope was 320 nA mM(-1) cm(-2) and the correlation coefficient was 0.990. Unlike conventional wet-chemical processes that are incompatible with mass production techniques, this dry-chemistry procedure has great potential for enabling high-throughput production of bioelectronic devices. 相似文献
155.
Shibatomi K Soga Y Narayama A Fujisawa I Iwasa S 《Journal of the American Chemical Society》2012,134(24):9836-9839
Highly enantioselective chlorination of β-oxo esters and subsequent stereospecific substitution of tertiary chlorides are described. Enantioselective chlorination of β-keto esters and malonates was performed using a chiral Lewis acid catalyst prepared from Cu(OTf)(2) and the newly developed spirooxazoline ligand 2 to yield the desired α-chlorinated products with high enantioselectivity (up to 98% ee). Nucleophilic substitution of the resulting chlorides proceeded smoothly to afford a variety of chiral molecules such as α-amino, α-alkylthio, and α-fluoro esters, without loss of enantiopurity. The results of X-ray crystallographic analysis proved that Walden inversion occurs at the chlorinated tertiary carbon center. These results supported the fact that the substitution proceeds via an S(N)2 mechanism. 相似文献
156.
In order to elucidate the enthalpic stabilization of a 2-methyl-1,4-butanediol system (2M14BD) and a 3-chloro-1,2-propanediol
(3C12PDO) system by mixing of each (R)- and (S)-enantiomers, three-body interaction energies are obtained by PW91/6-311G** and MP2/6-311G** level calculations. The differences
between homochiral interactions and heterochiral interactions in a 3C12PDO system are found. On the other hand, in 2M14BD
systems, very slight differences can be observed between the three-body interaction energies of the three ternary systems.
Further, the relationship between excess enthalpies and chiral interactions is discussed. 相似文献
157.
Hongli Liu Satoko Kido Tadashi Kamiyama Masao Fujisawa Takayoshi Kimura 《Journal of Thermal Analysis and Calorimetry》2010,102(3):1123-1133
To obtain further systematic information for the isomer systems, the excess molar enthalpies for binary (o + m), (o + p), (m + p)-isomers of methoxymethylbenzene, ethylmethylbenzene, diethylbenzene, chloromethylbenzene, tolunitrile and fluorobenzonitrile,
tolylacetonitrile were measured at 298.15 K. In this article, the results are discussed and compared with those of previous
works. The excess enthalpies of binary systems in different solid and liquid states were measured when the pure component
of o-/m-tolunitrile, fluorobenzonitrile was titrated into the prior (o + p) or (m + p) mixtures. A series calculation for the interaction energies (IE) between the isomers was carried out for the pair molecules by ab initio MO of Gaussian 09. Correlations between the excess
enthalpies at a molar fraction of x = 0.5 and the intermolecular energy are discussed. 相似文献
158.
Shibatomi K Kobayashi F Narayama A Fujisawa I Iwasa S 《Chemical communications (Cambridge, England)》2012,48(3):413-415
Highly enantioselective Diels-Alder reactions of β-fluoromethylacrylates were carried out in the presence of a Lewis acid activated chiral oxazaborolidine catalyst. These reactions yielded fluoromethylated cyclohexenes, including trifluoromethyl-, difluoromethyl-, and monofluoromethyl cyclohexenes, as nearly pure enantiomers. The resulting fluoromethyl cyclohexenes were converted into potential synthetic intermediates for bioactive compounds. 相似文献
159.
Takayoshi Kimura Takashi Yukiyama Masao Fujisawa 《Journal of Thermal Analysis and Calorimetry》2012,108(2):695-704
In order to investigate the contribution of the hydrophilic parts of guest molecules of aliphatic complexes to the inclusion
reaction, the thermodynamic properties of inclusion complexes of cyclodextrin (α-CD) with aliphatic nitriles [H(CH2)
n
CN: n = 1–8] into the α-CD cavity in dilute aqueous solutions were measured by a micro-calorimeter at 298.15 K. The thermodynamic
properties of inclusion for the octane nitrile system were different from those of others. The inclusion process of aliphatic
nitriles to α-CD has two kinds of major driving force of enthalpy and entropy driven inclusion. The interaction energies of
inclusion complexes of α-CD and aliphatic nitriles were determined by DFT calculation (B3LYP/6-31++G (d,p)) in water and compared
with the experimental results. DFT calculations were performed on the inclusion complexes of α-CD with seven nitriles of each
conformer. Both the gas phase interaction and solvent effect were taken into consideration. Also non-polar interactions between
aliphatic nitriles + α-CD in aqueous solution were calculated and herein the inclusion energy is discussed. 相似文献
160.