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161.
Aoyagi N Shimojo K Brooks NR Nagaishi R Naganawa H Van Hecke K Van Meervelt L Binnemans K Kimura T 《Chemical communications (Cambridge, England)》2011,47(15):4490-4492
Temperature-dependent yellow-to-red colour changes of uranyl thiocyanate complexes with 1-alkyl-3-methylimidazolium cations have been studied by different spectroscopic methods and this phenomenon is attributed to changes in the local environment of the uranyl ion, including the coordination number, as well as to cation-anion interactions. 相似文献
162.
Higashi T Shigemitsu Y Sagara T 《Langmuir : the ACS journal of surfaces and colloids》2011,27(22):13910-13917
Phase transitions of an adsorption layer of dibenzyl viologen (dBV) as a typical diaryl viologen on a basal plane of a highly oriented pyrolytic graphite (HOPG) electrode are described using voltammetry, in situ electrochemical scanning tunneling microscopy (EC-STM), and electroreflectance (ER) spectroscopy. A monolayer redox process at less negative potential than the bulk redox process was found to be the first-order faradaic phase transition between a gaslike adsorption layer of dication (dBV(2+)) and a 2D condensed monolayer of radical cation (dBV(?+)). Comparison of the results of cyclic voltammetry and potential step chronoamperometry was made with those of heptyl viologen (HV), which also undergoes a faradaic phase transition of the first order. It suggested that the contribution of intermolecular π-π interaction between benzyl groups of dBV to the phase transition is minor and apparently equivalent to interchain interaction between the heptyl chains of HV. In situ EC-STM images of the 2D condensed monolayer demonstrated stripe patterns of the rows of dBV(?+) molecules forming 3-fold rotationally symmetric domains. The results of the ER measurements also revealed that the orientation of the longitudinal molecular axis of the bipyridinium moiety of dBV(?+) molecules lying flat on the HOPG electrode surface, most likely with a side-on configuration. 相似文献
163.
K Akazaki F Toshimitsu H Ozawa T Fujigaya N Nakashima 《Journal of the American Chemical Society》2012,134(30):12700-12707
Synthesized single-walled carbon nanotubes (SWNTs) are mixtures of right- and left-handed helicity and their separation is an essential topic in nanocarbon science. In this paper, we describe the separation of right- and left-handed semiconducting SWNTs from as-produced SWNTs. Our strategy for this goal is simple: we designed copolymers composed of polyfluorene and chiral bulky moieties because polyfluorenes with long alkyl-chains are known to dissolve only semiconducting SWNTs and chiral binaphthol is a so-called BINAP family that possesses a powerful enantiomer sorting capability. In this study, we synthesized 12 copolymers, (9,9-dioctylfluorene-2,7-diyl)x((R)- or (S)-2,2'-dimethoxy-1,1'-binaphthalen-6,6-diyl)y, where x and y are copolymer composition ratios. It was found that, by a simple one-pot sonication method, the copolymers are able to extract either right- or left-handed semiconducting SWNT enantiomers with (6,5)- and (7,5)-enriched chirality. The separated materials were confirmed by circular dichroism, vis-near IR and photoluminescence spectroscopies. Interestingly, the copolymer showed inversion of SWNT enantiomer recognition at higher contents of the chiral binaphthol moiety. Molecular mechanics simulations reveal a cooperative effect between the degree of chirality and copolymer conformation to be responsible for these distinct characteristics of the extractions. This is the first example describing the rational design and synthesis of novel compounds for the recognition and simple sorting of right- and left-handed semiconducting SWNTs with a specific chirality. 相似文献
164.
Shunsuke KurosawaHidetoshi Kubo Kazuki UenoShigeto Kabuki Satoru IwakiMichiaki Takahashi Kojiro TaniueNaoki Higashi Kentaro MiuchiToru Tanimori Dogyun KimJongwon Kim 《Current Applied Physics》2012,12(2):364-368
It is an on-going challenge to verify the proton range in situ during proton therapy. Since the protons stop in target tissue, measurement of gamma-rays emitted either promptly from nuclear de-excitation or in pair from positron annihilation is the feasible method to monitor the proton range in-vivo. Using the technique of gamma collimation, we empirically demonstrated that the proton range and prompt gamma distribution are well correlated in the therapy energy range, and that measuring prompt gammas is a viable method for the clinical application. However, this collimation technique appears not to be applicable to passively scattered proton beams. The device chosen for gamma imaging in 2D is an electron tracking Compton camera, which images single-emission photons employing a gas chamber to induce Compton scattering. Images of prompt gammas were attained at the proton beam energy of 140 MeV. Measurements showed that gamma image in the energy range of 800-2000 keV provides a better match with the proton range compared to the image by lower energy gammas. 相似文献
165.
Goshi Sugano Kojiro Kawada Masayuki Shigeta Takeshi Hata Hirokazu Urabe 《Tetrahedron letters》2019,60(13):885-890
Iron-catalyzed δ-selective conjugate addition of methyl and cyclopropyl Grignard reagents to α,β,γ,δ-unsaturated esters and amides took place in good yields to give products exclusively with cis-β,γ-olefinic bond. 相似文献
166.
Hiroshi Yamaguchi Xin-Rong Zhang Shidei Higashi Mingjun Li 《Journal of magnetism and magnetic materials》2008
A new power generation system using electro-conductive polymer and its mixture with magnetic fluid is introduced. The system using non-poison electro-conductive polymer and its mixture with magnetic fluid and operating at room temperature is proposed in the present paper. The system could be used as a micro-distributed energy supply system for domestic use in the future. An experimental set-up is designed and established to investigate the performance of the power generation with an aid of a theoretical analysis of the power generation. It is found that the theoretical results are in good agreement with the measured data. Based on the obtained results, the electric output increases with Reynolds number, size of the test channel, magnetic strength and electric conductivity. It is understood that in order to obtain a practical power generation, priority should be put on increasing fluid flow velocity and magnetic field strength. 相似文献
167.
Excellent enantioselectivities up to 99.7% were achieved in the hydrogenation of (E)-beta-(acylamino)acrylates by the use of Rh(I)-complexes of electron-rich diphosphines, t-Bu-BisP and t-Bu-MiniPHOS. Low-temperature NMR experiments testify that monohydrides with beta-carbon atom of the substrate bound to rhodium are involved in the catalytic cycle. 相似文献
168.
Fukuji Higashi Kiyoshi Mitani 《Journal of polymer science. Part A, Polymer chemistry》2001,39(1):196-201
When a mixture of terephthalic acid (TPA) and various dicarboxylic acids was activated by tosyl chloride (TsCl)/dimethyl‐ formamide (DMF)/pyridine (Py), the resulting mixture became dissolved in Py, although the activated TPA was insoluble even at 120 °C. The temperature at which the mixture became soluble was varied with their compositions and the structure of diacids. Mixing the separately activated TPA and isophthalic acid (IPA) also improved the solubility of the activated TPA to some extent. The interesting phenomena were attributed to associations of the activated diacids through the dipole–dipole interactions between the carbonyl groups. The structures of associates were estimated in terms of transition temperatures of the thermotropic IPA/TPA‐methylhydroquinone and IPA/TPA‐chlorohydroquinone copolymers. The transition temperatures were significantly affected by the temperature of polycondensation, the preparative procedures of a mixture of the activated diacids, and several additives. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 196–201, 2001 相似文献
169.
Matsuda H Morikawa T Ishiwada T Managi H Kagawa M Higashi Y Yoshikawa M 《Chemical & pharmaceutical bulletin》2003,51(4):440-443
The methanolic extract and its fractions from the fresh flowers of Prunus mume SIEB. et ZUCC. were found to show scavenging effects on 1,1-diphenylpicryl-2-hydrazyl (DPPH) radical and superoxide. The fragrance constituents of P. mume were analyzed by GC-MS and a new polyacylated sucrose, prunose III, was isolated from the ethyl acetate-soluble fraction. The structure of prunose III was determined on the basis of chemical and physicochemical evidence as 4,3',4',6'-tetra-O-acetyl-6-O-p-coumaroylsucrose. In addition, the scavenging effects of the principal constituents on DPPH radical and superoxide were examined. 相似文献
170.
[reaction: see text] The iron-catalyzed cross-coupling reaction of alkenyl sulfides with Grignard reagents is described. While the cross-coupling proceeds efficiently at alkenyl-S bonds, almost no cross-coupling takes place at aryl-S bonds, attesting to a unique selectivity of iron catalysis. The beneficial effect of potentially coordinating 2-pyrimidyl group on sulfur is also described. 相似文献