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排序方式: 共有699条查询结果,搜索用时 187 毫秒
691.
Mehdi Baneshi Shigenao Maruyama Atsuki Komiya 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(7):1197-1204
Nano-particulate coatings with high reflectance against solar irradiation can control undesirable thermal heating by sunlight absorption. It can reduce the energy consumption for air conditioning of houses and cars. For the objects covered by these coatings and subjected to human sight, e.g. roofing surfaces, high dazzle of reflected visible light can offend the human eyes and spoil the fine view of covered objects. The authors introduced a new optimization method in designing pigmented coatings which considers both thermal and aesthetic effects in previous studies. The optimization is possible by controlling the material, size and concentration of pigment particles. The proposed coatings maximize the reflectance of near infrared (NIR) region to care the thermal effects and minimize the visible (VIS) reflected energy to keep the dark tone because of aesthetic appeal. Two different types of copper oxide pigment particles namely cupric oxide (CuO) and cuprous oxide (Cu2O) were considered in this study. The optimum characteristics and performances are obtained and compared with titanium dioxide (TiO2) particle as a typical cool pigment. The results show that cupric oxide has much better performance for our objective. 相似文献
692.
Nagai D Suzuki A Maki Y Takeno H 《Chemical communications (Cambridge, England)》2011,47(31):8856-8858
Reversible chain association/dissociation phenomenon via CO(2) responsive crosslinking/decrosslinking was detected in aqueous solutions of polyallylamine (PAA). The chain association/dissociation behavior was reversible and useful in the synthesis of porous crosslinked polystyrene, which suggested potential utility in the area of CO(2)-responsive separable adhesives, switches and sensors. 相似文献
693.
Dr. Naruyoshi Komiya Nao Itami Prof. Takeshi Naota 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(29):9497-9505
Morphology control for intense solid‐state phosphorescence of non‐emissive, but potentially emissive crystals of platinum complexes and the mechanistic rationale are described. A series of trans‐bis(salicylaldiminato)platinum(II) complexes bearing linear alkyl chains ( 1 a : n=5; 1 b : n=8; 1 c : n=12; 1 d : n=14; 1 e : n=16; 1 f : n=18) was synthesized and the solid‐state emission properties were examined by using crystals/aggregates prepared under various precipitation conditions. Crystals of 1 e , prepared using “kinetic” conditions including rapid cooling, high concentrations, and poor solvents, emit intensive yellow phosphorescence (λmax=545 nm) under UV irradiation at 298 K with an absolute quantum efficiency of 0.36, whereas all the crystals of 1 a – 1 f prepared using “thermodynamic” conditions including slow cooling, low concentrations, and good solvents were either non‐ or less emissive with Φ298K values of 0.12 ( 1 a ), 0.11 ( 1 b ), 0.10 ( 1 c ), 0.07 ( 1 d ), 0.02 ( 1 e ), and 0.02 ( 1 f ) under the same measurement conditions. The amorphous solid 1 e , prepared by rapid cooling and freeze‐drying, was also non‐emissive (Φ298K=0.02, 0.02). Temperature‐dependent emission spectra showed that the kinetic crystals of 1 e exhibit high heat‐resistance towards emission decay with increasing temperature, whereas the amorphous solid 1 e is entirely heat‐quenchable. This is a rare example of the change from a non‐emissive crystal into a highly emissive crystal by morphology control through crystal engineering. Emission spectra and powder X‐ray diffraction (XRD) patterns of the emissive, kinetic crystals of 1 e are clearly distinct from those of the less emissive, thermodynamic crystals of 1 a – 1 f . Single‐crystal XRD unequivocally establishes that the thermodynamic crystals of 1 d have a multilayered lamellar structure supported by highly regulated, consecutive π‐stacking interactions between imine moieties, whereas the kinetic crystals of 1 e have a face‐to‐edge lamellar structure with less stacking. These results lead to the conclusion that 1) morphology control of long‐chained complexes exclusively generates a metastable herringbone‐based lamellar packing motif that exhibits intense emission and high heat‐resistance, while 2) a thermodynamically stable, highly regulated, consecutive stacking motif is unfavorable for solid‐state emission. 相似文献
694.
Komiya N Muraoka T Iida M Miyanaga M Takahashi K Naota T 《Journal of the American Chemical Society》2011,133(40):16054-16061
Instant and precise control of phosphorescent emission can be performed by ultrasound-induced gelation of organic liquids with chiral, clothespin-shaped trans-bis(salicylaldiminato)Pt(II) complexes, anti-1. Nonemissive solutions of racemic, short-linked anti-1a (n = 5) and optically pure, long-linked anti-1c (n = 7) in organic liquids are transformed immediately into stable phosphorescent gels upon brief irradiation of low-power ultrasound. Emission from the gels can be controlled by sonication time, linker length, and optical activity of the complexes. Several experimental results indicated that structure-dependent homo- and heterochiral aggregations and ultrasound-control of the aggregate morphology are key factors for emission enhancement. 相似文献
695.
We have performed low-temperature scanning tunneling microscopy (STM) experiments on the cold-cleaved surface of YBa2Cu3Oy single crystals to study the nanoscale electronic order in high-Tc superconductors. STM images measured at low-bias voltage below ∼50 meV show the one-dimensional (1D) electronic modulation along the Cu-O bonds (parallel to the b-axis). The 1D electronic modulation does not have long-range order and the periodicity along the a-axis varies within the range ∼2a-4a depending on the position on the surface, indicating the glassy electronic order in the underdoped CuO2 plane. 相似文献
696.
697.
Toshihiro Otsuki Kohei Goto Zen Komiya 《Journal of polymer science. Part A, Polymer chemistry》2000,38(Z1):4661-4668
New hydrogenated ring‐opening metathesis polymers with excellent thermal and optical properties were developed. These polymers were prepared by the ring‐opening metathesis polymerization of ester‐substituted tetracyclododecene monomers followed by the hydrogenation of the main‐chain double bond. The degree of hydrogenation was an important factor for the thermal stability of the polymers, and as complete hydrogenation as possible was necessary to obtain a thermally stable polymer. The completely hydrogenated ring‐opening polymer derived from 8‐methyl‐8‐methoxycarbonyl‐substituted monomer has a glass‐transition temperature of 171 °C and a 5% weight‐loss temperature of 446 °C. This polymer has excellent thermal and optical properties because of its bulky and unsymmetrical polycyclic structure in the main chain and is an alternative to glass or other transparent polymers such as poly(methyl methacrylate) and polycarbonate resin. This polymer has also been used in a wide variety of applications, such as optical lenses, optical disks, optical films, and optical fiber. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4661–4668, 2000 相似文献
698.
699.