全文获取类型
收费全文 | 275篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
化学 | 220篇 |
晶体学 | 9篇 |
力学 | 1篇 |
数学 | 10篇 |
物理学 | 48篇 |
出版年
2023年 | 2篇 |
2020年 | 11篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 19篇 |
2011年 | 21篇 |
2010年 | 11篇 |
2009年 | 10篇 |
2008年 | 28篇 |
2007年 | 13篇 |
2006年 | 22篇 |
2005年 | 19篇 |
2004年 | 18篇 |
2003年 | 25篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有288条查询结果,搜索用时 109 毫秒
101.
Fan J Yudasaka M Kasuya D Azami T Yuge R Imai H Kubo Y Iijima S 《The journal of physical chemistry. B》2005,109(21):10756-10759
We present in this report a new type of particles with micrometer-order sizes, which we called giant graphitic balls (GG balls). The GG balls are produced by CO2 laser ablation of graphite together with single-wall carbon nanohorns. They have graphitic structures whose layers tend to align parallel with the GG-ball surfaces, resulting in polygonal-like arrangements. Comparing the GG-ball structure with that of the previously reported polygonal graphite-particles, the growth mechanism of the GG ball is discussed briefly. 相似文献
102.
Hideto Kakida Yozo Chatani Hiroyuki Tadokoro 《Journal of Polymer Science.Polymer Physics》1976,14(3):427-435
The crystal structure of poly(m-phenyulene isophthalamide) was determined by x-ray analysis. The triclinic cell, with a = 5.27 Å, b = 5.25 Å, c (fiber axis) = 11.3 Å, α = 111.5°, β = 111.4° and γ = 88.0° and space group P1, contains one monomeric unit. The crystal density is 1.47 g/cc. The molecules in the crystal are contracted by 1 Å per monomeric unit from the fully extended conformation, and the planes of the benzene rings and adjacent amide groups make angles of about 30°. The crystal is composed of molecular chains connected by N? H···O hydrogen bonds along the a and b axes forming a “jungle gym” network structure. The low tensile modulus of this polymer as compared with that of poly(p-phenylene terephthalamide) is attributed to the contracted molecular conformation. 相似文献
103.
Optimization of a sonochemical reactor using a pulsing operation 总被引:3,自引:0,他引:3
It is known that sonochemical reactions are enhanced by pulsing ultrasound. A method to optimize a sonochemical reactor using a pulsing operation was studied through the measurement of changes in sonoluminescence (SL) intensity from distilled water under various experimental conditions. It was confirmed that pulsing with a constant input power level enhanced SL intensity at lower power levels because of the higher amplitude of ultrasound. In contrast to this, a quenching effect due to excessive sound pressure appeared at higher power levels, and the pulsing operation was not effective under these conditions. Pulsing is more effective at higher frequency than at lower frequency. 相似文献
104.
Masayoshi Okubo Zhaoqun Wang Tsuyoshi Yamashita Eriko Ise Hideto Minami 《Journal of polymer science. Part A, Polymer chemistry》2001,39(18):3106-3111
A series of monomer‐adsorbed, crosslinked polystyrene/polydivinylbenzene composite particles having snowmanlike shapes were prepared by the dynamic swelling method that the authors had proposed in 1991. The morphology of the snowman‐shaped particles was estimated with the contact angle of the monomer phase on the polymer particle. Influences of the kind of monomers and polyvinyl alcohol colloidal stabilizer on the morphology were obviously observed and discussed from the viewpoint of thermodynamic stability. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3106–3111, 2001 相似文献
105.
Jianming Zhang Kohji Tashiro Abraham J. Domb Hideto Tsuji 《Macromolecular Symposia》2006,242(1):274-278
In the present research, we report for the first time the X-ray fiber pattern and polarized IR/Raman spectra taken for the uniaxially oriented disorder α form of PLLA, which can confirm the existence of the disorder PLLA α form (α′-form) and provide some new insight on the structural difference between the order and disorder α forms. 相似文献
106.
Mark Kerzhner Dinar Abdullin Jennifer Więcek Dr. Hideto Matsuoka Dr. Gregor Hagelueken Prof. Dr. Olav Schiemann Prof. Dr. Michael Famulok 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):12113-12121
Site‐directed spin labeling of RNA based on click chemistry is used in combination with pulsed electron‐electron double resonance (PELDOR) to benchmark a nitroxide spin label, called here d? . We compare this approach with another established method that employs the rigid spin label Çm for RNA labeling. By using CD spectroscopy, thermal denaturation measurements, CW‐EPR as well as PELDOR we analyzed and compared the influence of d? and Çm on a self‐complementary RNA duplex. Our results demonstrate that the conformational diversity of d? is significantly reduced near the freezing temperature of a phosphate buffer, resulting in strongly orientation‐selective PELDOR time traces of the d? ‐labeled RNA duplex. 相似文献
107.
Hideto Minami Atsushi Tanaka Yasuyuki Kagawa Masayoshi Okubo 《Journal of polymer science. Part A, Polymer chemistry》2012,50(13):2578-2584
It is known that it is difficult to polymerize carboxylic acid‐based monomer by atom transfer radical polymerization (ATRP) in polar solvents due to the protonation of ligand caused by acidic dissociation of the monomer. In this study, precipitation reverse ATRP of acrylic acid (AA) was carried out in supercritical carbon dioxide (scCO2), which is a nonpolar solvent to dissolve transition metal complexes, at 30 MPa and 45 °C. The polymerization proceeded smoothly and the conversion reached 86% for 3 h. After vending of scCO2, a dry poly(acrylic acid) (PAA) powder was obtained. Weight‐average molecular weight and polydispersity of the methylated PAA, which were measured by gel‐permeation chromatography after methyl esterification, were 3.5 × 104 and 2.07, respectively, indicating that the precipitation reverse ATRP proceeded with a bad control manner. However, chain extension of the methylated PAA with styrene was possible by ATRP in a bulk system. Moreover, PAA‐b‐polystyrene was successfully prepared in scCO2 directly by two‐step ATRP, although its molecular weight distribution was broad. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
108.
Hideto Akiba Hiroyuki Nishide Eishun Tsuchida Hideki Omichi Jiro Okamoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1125-1135
Acrylic acid (AA) and acrylamide (AAm) were graft copolymerized onto polyethylene powder by the preirradiation method. The PE powder grafted with both AA and AAm (PE-g-(AA-co-AAm)) rapidly adsorbed Tb ion with an efficiency higher than did PE powder grafted with AA (PE-g-AA). The complex formation constant of Tb ion with PE-g-(AA-co-AAm) was larger than that with PE-g-AA because the introduction of the acrylamide part decreased the steric hindrance for complexation between Tb and the carboxyl group of the graft chains. Tb ion was efficiently separated from transition metal ions, such as Co, upon passage of a solution through a column packed with PE-g-(AA-co-AAm). 相似文献
109.
Akimitsu Ishihara Satoshi Tominaka Shigenori Mitsushima Hideto Imai Osamu Sugino Ken-ichiro Ota 《Current Opinion in Electrochemistry》2020
To obtain an ideal electrocatalysts for hydrogen fuel cells, we investigated group 4 and 5 oxide-based compounds because of their high degree of freedom. First-principles calculations revealed that oxide surfaces such as those of titanium oxide could break down the universal scaling to achieve the ideal state of the oxygen reduction reaction. We experimentally clarified that the active sites were oxygen vacancies for tantalum and zirconium oxides, in addition to doped foreign elements and crystalline structures for titanium oxide. We successfully demonstrated that precious metal-free and carbon-free oxide-based cathodes have high quality active sites and superior durability in 0.1 M sulfuric acid at 80°C. Our strategy was developed as follows: (1) Active sites are created on the oxide surface by modifying the crystalline structure and electronic states and (2) electrons participating in the oxygen reduction reaction are supplied by nanosized oxide particles and oxide films through the tunneling effect of electrons. 相似文献
110.
Hideto Tsuji Hajime Kabashima Hideaki Kita Hideshi Hattori 《Reaction Kinetics and Catalysis Letters》1995,56(2):363-369
KF/alumina catalyst exhibits activity for double bond isomerization of 1-pentene at 273 K when pretreatedin vacuo in the temperature range 573–673 K, while the activity for Michael addition of nitromethane to butene-2-one does not change much with the pretreatment temperature. 相似文献