全文获取类型
收费全文 | 85篇 |
免费 | 0篇 |
专业分类
化学 | 60篇 |
力学 | 3篇 |
数学 | 7篇 |
物理学 | 15篇 |
出版年
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 7篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1974年 | 1篇 |
1972年 | 4篇 |
1970年 | 1篇 |
排序方式: 共有85条查询结果,搜索用时 0 毫秒
1.
Eishun Tsuchida Kunio Mishima Kiwamu Kitamura Isao Shinohara Setsuo Mimashi 《Journal of polymer science. Part A, Polymer chemistry》1972,10(12):3627-3637
In order to clarify the kinetic features of the styrene (A)–methyl methacrylate (B)–CCl4(S) cooligomerization system, a computer simulation was carried out. The experimental data on the degree of polymerization and the deviation of the cooligomer composition from the statistical steady-state composition were comparatively well explained by calculations based on the kinetic equations derived from the assumed reaction scheme and the values of the velocity coefficients, although the values of the four velocity coefficients in the initiation step and the velocity coefficient of the termination by the coupling of two solvent radicals were estimated. The results of the calculation of the rate of each component reaction show that the following two reactions are the most important in the initiation and in the transfer and termination steps when the [S]/([A] + [B]) ratio is large: where, A, A*, and P are styrene, polystyryl radical, and the cooligomer, respectively. Moreover, it was concluded that the deviation of the cooligomer composition from the statistical steady-state composition was caused by these two reactions. 相似文献
2.
Photoreaction dynamics of 2-(3-benzoylphenyl)propionic acid (ketoprofen, KP), one of nonsteroidal anti-inflammatory drugs, with histidine in a phosphate buffer solution (pH 7.4) was investigated with the laser flash photolysis. The deprotonated form of KP (KP(-)) was decarboxylated via UV laser excitation to form a carbanion. It was found that histidine accelerates the protonation reaction of the carbanion to 3-ethylbenzophenone ketyl biradical (3-EBPH) for the first time. The experimental results of the photoreaction of KP with alanine as well as the photoreaction of KP with 4-methylimidazole (a part of the side chain of histidine) in methanol, clearly showed that the protonated form of histidine is a key species for the protonation reaction of the carbanion. These series of the initial reactions should result in the occurrence of photosensitization in vivo. The reaction mechanism was discussed in detail. 相似文献
3.
Peikov V Sasai R Tanigawa M Petkanchin I Yamaoka K 《Journal of colloid and interface science》2006,295(2):445-456
Steady-state and decay birefringence, expressed in terms of the optical phase retardation per cell length delta/d, was measured on beta-FeOOH in aqueous ionic media at 633 nm and at 25 degrees C by an electric square-pulse technique over a wide range of field strength E to ca. 6 kV/cm. The field-strength dependence of both delta/d and field-free rotational relaxation time tau was determined at the sample concentrations between 0.0011 and 0.055 g/L and in the 0.02-2.0 mM NaCl concentration range. Extrapolation of both delta/d and tau values to infinitely high fields (E(2)-->infinity) could yield birefringence- and weight-average quantities, respectively. Observed tau values were decreased at weak fields but leveled off to ca. 0.3 ms at very high fields due to a slight polydispersity regarding the length and volume of particles. The weight-average relaxation time tau(w) was calculated with Perrin's expressions theoretically from the length, width, and volume of beta-FeOOH particles estimated in the dried state from electron micrograph. These quantities were variously averaged. The size distribution was discussed in terms of observed discrete histogram and theoretical (Weibull and Lansing-Kraemer) distribution functions. The sign of observed delta/d value was always positive. The infinitely high-field (delta/d)(infinity) values and the reduced optical anisotropy factor Delta g/n were evaluated by fitting to theoretical orientation functions. The intrinsic birefringence (n3-n1) could be estimated with the mean refractive index n(p) reported in the literature. For the spindle-shaped particle with an axial ratio of ca. 4, the sign of Delta g/n is always positive, whereas the quantity (n3-n1) was either negative (n(p) > 2.35) or positive (n(p) < 2.05) in sign or nearly zero (ca. n(p) = 2.26), depending critically on the n(p) values. 相似文献
4.
Optical Review - A novel color removal method for digital color images is proposed. In this method, differences of colors in an input color image are reflected effectively, and the perceived... 相似文献
5.
Itaru Hibino Minoru Okita Takayuki Inoue Yasuhiro Banno Masahiro Hoso 《Physical Therapy Research》2008,11(1):1-6
Immobilization is often associated with decreased muscle elasticity. This condition is known as muscle contracture; however, the mechanism remains unclear. The purpose of this study was to clarify the mechanism governing muscle contracture in rat soleus muscle by identifying changes in ankle joint mobility, insoluble collagen concentration and type I and type III collagen isoforms following 1- and 3-week immobilizations. Following a 1-week immobilization, range of motion (ROM) of dorsiflexion declined to 90% of the control value; additionally, ROM dropped to 67.5% of the control value after a 3-week immobilization. This finding suggested that ankle joint mobility decreases in conjunction with extended periods of immobilization. Insoluble collagen concentration in soleus muscles, which was unchanged after 1 week of immobilization, increased 3 weeks after immobilization. These results may be indicative of collagen fibers with strong intermolecular cross-links contained in the muscle was made increased relatively by 3 weeks of immobilization. Therefore, the change in intermolecular cross-links may be significant in terms of progress of muscle contracture with longer periods of immobilization. On the other hand, the ratio of type III to type I collagen isoforms in muscular tissue increased following a 1-week immobilization; moreover, this ratio remained constant after 3 weeks of immobilization. These data suggested that muscle immobilization may induce type III collagen isoform expression. The increase in the ratio of type III to type I collagen isoforms do not change in parallel with the increase in the limitation in ROM; however, this phenomenon probably is not closely related to the progress of muscle contracture. The change of collagen isoform in immobilized muscle may be involved in the mechanism governing the progression of muscle fibrosis. 相似文献
6.
Sho Hayakawa Taira Okita Mitsuhiro Itakura Masaatsu Aichi Katsuyuki Suzuki 《哲学杂志》2018,98(25):2311-2325
We conduct kinetic Monte Carlo simulations for the conservative climb motion of a cluster of self-interstitial atoms (SIAs) towards another SIA cluster in BCC–Fe; the conservative climb velocity is inversely proportional to the fourth power of the distance between them, as per the prediction based on Einstein’s equation. The size of the climbing cluster significantly affects its conservative climb velocity, while the size of the cluster that originates the stress field does not. The activation energy for the conservative climb is considerably greater than that derived in previous studies and strongly dependent on the climbing cluster size. The results presented in this study are the atomistic evaluation of the behaviour of SIA clusters through three-dimensional motion, which cannot be achieved using molecular dynamics techniques alone. 相似文献
7.
8.
We derive here for the first time the equations that describe the combined motion and rotation of small prismatic dislocation loops in stress fields. When the applied torque is balanced by the self-torque of the loop, we show how the solution can be obtained for the loop orientation, and how this orientation affects the glide force on the loop. 相似文献
9.
Spectroelectrochemical properties of monosilane bridged diphenylamine (5,10-dihydro-2,8-diphenyl-5, 10,10-trimethylphenazasiline, Phenaz) and disilane bridged diphenylamine (2,8-diphenyl-10,11-dihydro-10,11-disila-5,10,10,11,11-pentamethyldibenzo[b,f]azepine, DSiAzep) were investigated. The electrochemical oxidation of Phenaz was reversible and its cyclic voltammogram was almost the same shape as that of diphenylamine (DPA). The electrochemical oxidation of DSiAzep was followed by irreversible reactions leading to the cleavage of the Si-Si bond. On electrochemical oxidations of Phenaz and DPA, the formation of a stable radical cation was observed with UV-Vis spectroscopy. In comparison with the absorption characteristics of oxidized radical cations, it was seen that the oxidized radical cation of Phenaz was more delocalized than that of DPA. In the same way, absorption characteristics of oxidized DSiAzep were observed to be different from those observed in Phenaz and DPA. 相似文献
10.
Yoshihiro Takebayashi Hiroyuki Hotta Atsushi Shono Katsuto Otake Kiwamu Sue Satoshi Yoda Takeshi Furuya 《Journal of solution chemistry》2009,38(5):545-555
Acid-base equilibria between 2,5-dichlorophenol (DCP) and various bases (LiOH, NaOH, and KOH) were studied in ambient to supercritical
methanol, by measuring the absorption spectrum of DCP at alkali metal hydroxide molalities ranging up to 10 mmol⋅kg−1, at temperatures up to 250 °C and a pressure of 25.0 MPa. The spectrum was deconvoluted into contributions for the acidic
(HA) and basic (A−) forms of DCP, taking into account a blue shift of the phenolate (A−) spectrum due to the effect of ion pairing with an alkali metal cation. Degrees of dissociation of DCP determined from the
spectra suggested that the dissociation constant of DCP has a maximum around 150 °C, whereas that of KOH decreases with temperature.
The phenolate-alkali metal ion pairing was examined from the peak shift of the phenolate spectrum in the presence of Li+, Na+, and K+. A smaller cation radius and higher temperature (thus a lower dielectric constant for methanol) give rise to stronger electrostatic
interaction in the ion pair. The basicities of the alkali metal hydroxides in supercritical methanol were compared using DCP
as an indicator, and were shown to follow the order LiOH < NaOH ≤ KOH. This order is the same as that for the catalytic effect
of alkali metal hydroxides on the methylation of phenol in supercritical methanol (Takebayashi et al.: Ind. Eng. Chem. Res.
47:704–709, 2008).
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献