全文获取类型
收费全文 | 156篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
化学 | 135篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 5篇 |
物理学 | 17篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 14篇 |
2005年 | 10篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
排序方式: 共有162条查询结果,搜索用时 187 毫秒
81.
Sol–gel coating of metal oxides on polymer substrates is a useful process to fabricate various organic–inorganic hybrid materials
under mild conditions. However, this process is hardly applicable to pristine polyimide (PI) films because their surfaces
do not display effective functional groups for metal oxide coatings. In this study, we firstly examined direct sol–gel coating
of titania thin layers on unmodified PI film surfaces. The results confirmed homogeneous, ultrathin titania layer coating
and showed that the thickness and microscopic morphology of the titania layers were affected by titanium alkoxide concentrations
in the spin coating solutions. We next investigated titania layer coating on surface-modified PI films that prepared using
alkaline hydrolysis, which generated carboxylic acid groups on the film surfaces. Optimal hydrolysis time was determined using
FT-IR spectroscopy and contact angle measurements. After sol–gel titania coating on the hydrolyzed PI film surfaces, the Scotch
tape test was conducted to evaluate adhesion strength between the titania layers and PI film surfaces. Morphological observations
of the sample surfaces after the tests clearly showed that surface modification of PI films increased titania layer adhesions.
Effect of hydrothermal treatments on film formability and adhesion strength between titania-PI film interfaces was also evaluated. 相似文献
82.
Solutions of suspended particles of nanodiamond and nanosilica in deionized water 25 mg/10 mL were prepared for the purpose of achieving saturation adsorption. The respective saturation thresholds and adsorption reaction constants of lysozyme of extremely diluted concentrations 0–1000 nmol/L in 7 mmol/L (potassium phosphate buffer solution) PPBS on the surfaces of nanodiamond and nanosilica of 100 nm diameter have been measured. The adsorbed quantities of lysozyme on a unit surface area of both nanoparticles can be derived. The possible influences by the adsorption surface profile and adsorption surface area, adsorption ability of the nanoparticles, strength and activity of lysozyme have been discussed. 相似文献
83.
Taniguchi Y Nakamura A Senko Y Nagatsugi F Sasaki S 《The Journal of organic chemistry》2006,71(5):2115-2122
Triplex-forming oligonucleotides (TFOs) are sequence-specific DNA-binding agents, but their target duplexes are limited to homopurine/homopyrimidine sequences because of interruption of the pyrimidines bases in the purine region. This problem has not been fully solved despite a wide variety of studies. Recently, we have developed a bicyclic system as a novel scaffold for nucleoside analogues (WNA, W-shaped nucleoside analogues) and determined two useful compounds, WNA-betaT (2) and WNA-betaC (5), for highly stable and selective triplex formation at a TA and a CG interrupting site, respectively. However, subsequent investigations have shown that the triplex formation using WNA is dependent on the neighboring bases of the TFOs. In this study, we have synthesized new WNA derivatives having halogenated recognition bases or benzene rings and evaluated the effects of the modifications on the triplex stability as well as selectivity. It has been found that the WNA-betaT analogues holding 5-halogenated pyrimidine bases (WNA-beta(Br)U (3) and WNA-beta(F)U (4)) exhibit high CG-selectivity. On the other hand, the WNA-betaT derivatives having the bromo-substituted benzene ring (mBr-WNA-betaT (10) and oBr-WNA-betaT (11)) have shown high selectivity to a TA interrupting site with high stability in the sequences to which the original WNA-betaT do not bind. Thus, sequence-dependency has been overcome by the sequence-dependent use of WNA-betaT, mBr-WNA-betaT, and oBr-WNA-betaT. 相似文献
84.
Hiroshi Maruoka Kenji Yamagata Fumi Okabe Yukihiko Tomioka 《Journal of heterocyclic chemistry》2006,43(4):859-865
85.
[structure: see text] The chiral recognition ability of enantiopure O-methyl, O-ethyl, O-propyl, and O-phenyl phenylphosphonothioic acids (1a-d) for various kinds of racemic amines during salt crystallization and the chiral recognition mechanism were thoroughly investigated. The chiral recognition abilities of enantiopure 1a-d for a wide variety of racemic amines varied in a range of 6 to >99% enantiomeric selectivity. Deposited less-soluble diastereomeric salts were classified into two categories, prism- and needle-type crystals; the prism-type crystals were composed of a globular molecular cluster, while there existed a 2(1) column in the needle-type crystals. In contrast to a general observation of a similar 2(1) column in the less-soluble diastereomeric salt crystals of chiral primary amines with chiral carboxylic acids, the globular molecular cluster is a very unique hydrogen-bonding motif that has never been constructed in diastereomeric salt crystals. Excellent chiral recognition was always achieved when the less-soluble diastereomeric salts were prism-type crystals. Significant correlations were found between the degree of the chiral recognition with 1a-d, the crystal shape of the less-soluble diastereomeric salts, and the hydrogen-bonding motif (molecular cluster/2(1) column). The chiral recognition mechanisms via the molecular cluster and the 2(1) column formations are discussed in detail on the basis of X-ray crystallographic analyses. 相似文献
86.
H. Sato Y. Hirashima A. Suzuki M. Goto M. Tokita 《Journal of Polymer Science.Polymer Physics》2005,43(7):753-763
Polyelectrolyte hydrogels, physically crosslinked by metal ions, were synthesized using poly(sodium acrylate) as the main constituent and Al ions as the crosslinker. The swelling ratio of the gel was measured whenever the solvent water was repeatedly exchanged in a constant interval. The as‐synthesized gel exhibited two relaxation processes; the gel swelled at the first stage, then shrunk very slowly at the second stage, and recovered to the initial size just after the gelation (ultimately, the gel became smaller than that). The relaxation times of both processes were found longer (exceptionally longer for the shrinking process) than the conventional collective diffusion of polymer networks. The diffused amounts of Al ions and Na counter ions in the solvent were also measured at each water exchange. The diffusion of Al ions into the solvent was found to finish when the swelling ratio took the maximum (at the end of the first stage), while Na ions continued to diffuse until the diameter became the final one (at the end of the second stage). The microscopic structural changes by the repeated water exchange were obtained by the measurements of ATR FT‐IR spectroscopy on the gels with different swelling ratios. The carboxyl groups were gradually protonated on both stages, and the formation of hydrogen bonding was accelerated on the second stage. Effects of the repeated water exchange on the swelling behavior are discussed in terms of the diffusion of Al ions into the solvent, the exchange of Na counter ions by protons, and the formation of hydrogen bonding. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 753–763, 2005 相似文献
87.
Yasumasa Hirashima 《Topology and its Applications》2007,154(12):2412-2424
Pairings and copairings of topological spaces induce pairings of function spaces. These induced pairings of function spaces are studied. For this purpose, the C-open topology of function spaces is studied for subcategories C of Top. It is shown that the C-open topology enjoys good properties for homotopy theory. Making use of the C-open topology, theory of induced pairings is established and fundamental results on pairings which deduce various commutativity properties of elements in homotopy set are extended to function spaces. 相似文献
88.
Kaoru Nakajima Yuki Komai Eriko Watanabe Fumi Moritsuka Shimako Anzai Kashiko Kodate 《Optical Review》2007,14(4):201-207
We designed and developed a volume phase holographic (VPH) grism with high resolution and high efficiency in the near-infrared
light domain (1550 nm) to be applied as a wavelength de-multiplexing device of a photonic network. In order to achieve both
diffraction efficiency of over 80% and wavelength resolution of 0.08 nm, we newly designed and fabricated a VPH grism with
high efficiency and high wavelength resolution in near-infrared wavelength region by sandwiching a VPH grating between prisms.
An active feedback control technique was introduced to a two-beam interference exposure system, and we also applied it to
a wavelength de-multiplexing device for a photonic network. Consequently, a VPH grism was successfully fabricated with diffraction
efficiency of over 80% by employing the Bragg condition of 1550 nm at the incident wavelength from 1530 to 1570 nm, and high
refractive index modulation of 0.047 was confirmed. 相似文献
89.
Shin-ichi Hirashima 《Tetrahedron》2006,62(33):7887-7891
Alcohols were found to be oxidized to the corresponding carboxylic acid in the presence of a catalytic inorganic bromo source, for example, lithium bromide, bromine, and hydrobromic acid, under photo-irradiation. 相似文献
90.
Synthetic oligonucleotides (ONs) are valuable tools that interfere with gene expression by specifically binding to target genes in a sequence-specific manner. Reactive ONs containing cross-linking agents are expected to induce efficient inhibition because they bind covalently to target genes. In recent years, researchers have reported several cross-linking reactions that target DNA induced by external stimuli. This short review highlights recently developed novel cross-linking reactions, focusing particularly on nucleoside derivatives developed by our group. 相似文献