全文获取类型
收费全文 | 274篇 |
免费 | 10篇 |
专业分类
化学 | 209篇 |
晶体学 | 3篇 |
力学 | 3篇 |
数学 | 20篇 |
物理学 | 49篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 14篇 |
2012年 | 16篇 |
2011年 | 18篇 |
2010年 | 11篇 |
2009年 | 12篇 |
2008年 | 19篇 |
2007年 | 15篇 |
2006年 | 21篇 |
2005年 | 26篇 |
2004年 | 16篇 |
2003年 | 19篇 |
2002年 | 14篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有284条查询结果,搜索用时 46 毫秒
51.
Keiko Ohkura Hidekazu Nishizawa Takashi Obi Akira Hasegawa Masahiro Yamaguchi Nagaaki Ohyama 《Optical Review》2000,7(3):193-198
In the analysis of a medical image database aimed at formulating useful knowledge for image diagnosis requires an unsupervised image processing technique without preconceived knowledge. In this paper, we propose a method for unsupervised image segmentation, which is suitable for finding the features contained in an image. A small region around each pixel is considered as a pattern vector, and the set of pattern vectors acquired from the whole image is classified using the hierarchical clustering technique. In hierarchical clustering, the classification of pattern vectors is divided into two clusters at each node according to the statistical criterion based on the entropy in thermodynamics. Results of the test image generated by the Markov random field (MRF) model and real medical images photomicrographs of a colon tumor are shown. 相似文献
52.
Satoru Yamanaka Naoki Suzuki Bong Kuk Lee Hea Yeon Lee Hidekazu Tanaka Tomoji Kawai 《Solid State Communications》2009,149(17-18):729-733
53.
Coherent phase control of the photodissociation reaction of the dimethylsulfide has been achieved by means of quantum-mechanical interference between one- and three-photon transitions. Dimethylsulfide was irradiated by fundamental and frequency-tripled outputs of a visible laser (600.5-602.5 nm), simultaneously to yield CH3S+ and CH3SCH2+ fragment ions. The branching ratio of the two product channels could be modulated with variation of the phase difference between the light fields. This accounted for the difference between the molecular phases of the two product channels. The phase lag was observed to have a maximum value of 8 degrees at 601.5 nm. This is the first result of a selective bond breaking in a polyatomic molecule by the coherent phase control. 相似文献
54.
Akihisa?Kaneko Pankaj?Sehgal Hidekazu?DoeEmail author 《Colloid and polymer science》2012,290(4):323-330
The pH dependence of an anionic surfactant, sodium N-dodecanoylsarcosinate (SLAS), has been studied by measuring interfacial tension, fluorescence, dynamic light scattering,
etc., in aqueous solutions with phosphate and borate buffers. The interfacial tension (γ) of SLAS decreases remarkably with a pH decrease and is constant at pH > 7.3. The observed values for the critical micelle
concentration (cmc) and the surfactant concentration at which its γ value is reduced by 20 mN/m from that of pure water (C
20) decrease with a pH decrease, while those also become constant at pH > 6.5 and >7.3, respectively. On the other hand, the
interfacial excess of SLAS increases at pH < 7.3. These interfacial behaviors have been further investigated by the addition
of Tl+ which replaces Na+ of SLAS. The observed γ values of LAS− with the different counter cations are in the order of H+ < Tl+ < Na+. In order to reveal aggregation properties of SLAS, the aggregation number (N
agg), the micropolarity, the hydrodynamic radius (R
h) of micelle, and the fluorescence anisotropy of Rhodamine B (r) have been evaluated at various pHs. The N
agg value shows a decreasing tendency with a pH increase. The I
1/I
3 ratio and the R
h values do not strongly depend on pH. The r value decreases until pH 7 and remains constant at pH > 7.0. These interfacial and micelle properties have been discussed
in detail considering the electrostatic interaction and the molecular structures of the hydrophilic headgroup. 相似文献
55.
56.
Pankaj?SehgalEmail author Hidekazu?Doe Manu?Sharma Daniel?E.?Otzen 《Colloid and polymer science》2005,283(11):1219-1225
The synergistic behavior of sodiumdodecylsulfate (SDS) and 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC) binary mixtures
has been studied with interfacial and pyrene fluorescence(I
1/ I
3) intensity measurements. From the interfacial data, the interfacial parameters; the maximum surface excess (Γmax), or the minimum area per molecule (A
min), and the surface pressure at the critical micellar concentration (πcmc) have been evaluated. The cmc value has been used for evaluating the free energies of micellization (ΔG
o
m). The mixed micelle formation was evaluated with the help of the Clint equation. The SDS plus DHPC mixed micelles showed
negative departure from ideality indicating synergistic interactions between the unlike components. The quantitative analysis
of mixed micelle, mixed monolayer and the composition of the mixed micelle was carried out with the help of regular solution
approximation. The interaction parameters, β and βσ, in the mixed micelle as well as in the mixed monolayer, respectively showed negative values indicating synergistic behavior
of SDS and DHPC molecules. 相似文献
57.
Formation and structure of titanium alkyl phosphates 总被引:1,自引:0,他引:1
Titanium alkyl phosphates (TiAP) synthesized by the reactions of Ti(SO(4))(2) with monohexyl, monooctyl, and monodecyl phosphates in aqueous media were characterized by various means. The XRD patterns of TiAP showed a strong diffraction peak and two weak ones below 2theta=15 degrees. The TiAP particle prepared using octyl phosphate gave rise to the lattice patterns having uniform alternating spacings of ca. 0.7 and ca. 2.0 nm. When treated at 900 degrees C, TiAP crystallized as TiP(2)O(7). The chemical formula could be shown as (ROPO(3))(2)Ti.0.44H(2)O. These facts suggest that the TiAP is composed of a multilayer alternating bimolecular layer of alkyl phosphates and hydrated titanium phosphate phase. Alkyl groups in the layers were removed by outgassing above 300 degrees C to give the materials having mesopores with a diameter of ca. 2 nm. 相似文献
58.
Takeuchi Masanobu Kageyama Shinji Suzuki Hidekazu Wada Takahiro Notsu Yoshitada Ishii Fumiyoshi 《Colloid and polymer science》2003,281(12):1178-1183
Colloid and Polymer Science - The composition of vehicle on the reversible sol-gel transition temperature in a ternary system made up of methylcellulose (MC), polyethylene glycol (PEG), and citric... 相似文献
59.
A new mathematical model for finding the optimal harvesting policy of an inland fishery resource under incomplete information is proposed in this paper. The model is based on a stochastic control formalism in a regime‐switching environment. The incompleteness of information is due to uncertainties involved in the body growth rate of the fishery resource: a key biological parameter. Finding the most cost‐effective harvesting policy of the fishery resource ultimately reduces to solving a terminal and boundary value problem of a Hamilton‐Jacobi‐Bellman equation: a nonlinear and degenerate parabolic partial differential equation. A simple finite difference scheme for solving the equation is then presented, which turns out to be convergent and generates numerical solutions that comply with certain theoretical upper and lower bounds. The model is finally applied to the management of Plecoglossus altivelis, a major inland fishery resource in Japan. The regime switching in this case is due to the temporal dynamics of benthic algae, the main food of the fish. Model parameter values are identified from field measurement results in 2017. Our computational results clearly show the dependence of the optimal harvesting policy on the river environmental and biological conditions. The proposed model would serve as a mathematical tool for fishery resource management under uncertainties. 相似文献
60.
Matsumoto Yutaka Takeo Yoko Egawa Satoru Yamaguchi Gota Yokomae Shunya Takei Masashi Yumoto Hirokatsu Koyama Takahisa Ohashi Haruhiko Tono Kensuke Yabashi Makina Mimura Hidekazu Kimura Takashi 《Optical Review》2022,29(1):7-12
Optical Review - A microfluidic device was developed for coherent diffraction imaging using an X-ray free-electron laser (XFEL-CDI). Liquid samples, which are separately packed in reservoirs of the... 相似文献