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861.
Moriyuki Sato Yoichi Matsuoka Isao Yamaguchi 《Journal of polymer science. Part A, Polymer chemistry》2007,45(14):2998-3008
New thermotropic liquid crystalline (LC) hyperbranched (HB) polyesters containing 2,5‐diphenyl‐1,3,4‐thiadiazole (DTD) unit as mesogen in the interiors were prepared at various mole ratios (A2/B3) by melt and solution polycondensations of a dioxydiundecanol of DTD (A2) and 1,2,3‐propanetricarboxylic acid (B3) via the A2 + B3 approach and their LC and optical properties were investigated. FTIR and 1H‐NMR spectroscopies indicated that all the expected HB polyesters, which show good solubilities in organic solvents, are produced without gelation during the polymerization. Among them, the HB polymer prepared in the mole ratio of A2/B3 = 3/2 by the solution polycondensation had the highest inherent viscositiy. DSC measurents, polarizing microscope observations of optical textures, and X‐ray analyses suggested that the LC properties of HB polymers depend on the polymerization methods and the feed mole ratios. In the HB polymers prepared using the melt polycondensation, only the polymer prepared in the mole ratio of A2/B3 = 3/1 formed a highly‐ordered, tilted, crystal‐like smectic phase, but all the polymers prepared by the solution polycondensation formed highly‐ordered, tilted, smectic phases. Solution and solid‐state UV‐vis and photoluminescent (PL) spectra indicated that the HB polymers show maximum absorbances and blue‐light emission on the basis of the DTD unit, where the Stokes‐shifts were observed, probably because of intermolecular aggregation effects © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2998–3008, 2007 相似文献
862.
DMA is a tool for studying linear viscoelastic behavior of polymers over ranges of temperature and frequency. Viscoelasticity has its origin in the complex molecular behavior of the polymer. A theoretical master curve has been constructed, based predominantly on thermodynamic theories of polymer molecular conformations, and their intermolecular cooperativity.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
863.
M. Aoyama A. Sagisaka S. Matsuoka Y. Akahane F. Nakano K. Yamakawa 《Applied physics. B, Lasers and optics》2000,70(7):S149-S153
We fully characterize a high-peak-power, ultrashort laser pulse in a Ti:sapphire chirped-pulse amplification laser system. The contrast, temporal, and spectral phases of the 20-fs pulse are determined by using high-dynamic-range cross-correlation and frequency-resolved optical gating techniques. Minimization of the total phase error can be achieved by balancing the phase terms of the group delay dispersion and quartic. The laser system is currently being applied to perform high-field atomic ionization experiments at 1020 W/cm2. 相似文献
864.
Christian A. Sandoval Dr. Fusheng Bie Aki Matsuoka Yoshiki Yamaguchi Dr. Hiroshi Naka Prof. Dr. Yuehui Li Koichi Kato Prof. Dr. Noriyuki Utsumi Kunihiko Tsutsumi Takeshi Ohkuma Prof. Dr. Kunihiko Murata Dr. Ryoji Noyori Prof. Dr. 《化学:亚洲杂志》2010,5(4):806-816
Aromatic ketones are enantioseletively hydrogenated in alcohols containing [RuX{(S,S)‐Tsdpen}(η6‐p‐cymene)] (Tsdpen=TsNCH(C6H5)CH(C6H5)NH2; X=TfO, Cl) as precatalysts. The corresponding Ru hydride (X=H) acts as a reducing species. The solution structures and complete spectral assignment of these complexes have been determined using 2D NMR (1H‐1H DQF‐COSY, 1H‐13C HMQC, 1H‐15N HSQC, and 1H‐19F HOESY). Depending on the nature of the solvents and conditions, the precatalysts exist as a covalently bound complex, tight ion pair of [Ru+(Tsdpen)(cymene)] and X?, solvent‐separated ion pair, or discrete free ions. Solvent effects on the NH2 chemical shifts of the Ru complexes and the hydrodynamic radius and volume of the Ru+ and TfO? ions elucidate the process of precatalyst activation for hydrogenation. Most notably, the Ru triflate possessing a high ionizability, substantiated by cyclic voltammetry, exists in alcoholic solvents largely as a solvent‐separated ion pair and/or free ions. Accordingly, its diffusion‐derived data in CD3OD reflect the independent motion of [Ru+(Tsdpen)(cymene)] and TfO?. In CDCl3, the complex largely retains the covalent structure showing similar diffusion data for the cation and anion. The Ru triflate and chloride show similar but distinct solution behavior in various solvents. Conductivity measurements and catalytic behavior demonstrate that both complexes ionize in CH3OH to generate a common [Ru+(Tsdpen)(cymene)] and X?, although the extent is significantly greater for X=TfO?. The activation of [RuX(Tsdpen)(cymene)] during catalytic hydrogenation in alcoholic solvent occurs by simple ionization to generate [Ru+(Tsdpen)(cymene)]. The catalytic activity is thus significantly influenced by the reaction conditions. 相似文献
865.
Sulistyo Saputro Kô Takehara Kazuhisa Yoshimura Shiro Matsuoka Narsito 《Electroanalysis》2010,22(23):2765-2768
The electrochemical detection of free chlorine based on the reduction at a gold electrode has been studied. The differential pulse voltammetric curves exhibited well‐defined cathodic peaks. Investigations with this system suggested that the active species in the cathodic reaction is HClO. Excellent reproducibility was demonstrated at pH 5. The peak height could be used for accurate and rapid determination of free chlorine in a sample water. A linear relationship (r2=0.99) was found for the concentration range of 1–5 mg Cl dm?3 and the detection limit was estimated to be 0.04 mg Cl dm?3. 相似文献
866.
Surface properties and aggregate morphology of partially fluorinated carboxylate-type anionic gemini surfactants 总被引:1,自引:0,他引:1
Tomokazu Yoshimura Miri Bong Keisuke Matsuoka Chikako Honda Kazutoyo Endo 《Journal of colloid and interface science》2009,339(1):230-235
Three anionic homologues of a novel partially fluorinated carboxylate-type anionic gemini surfactant, N,N′-di(3-perfluoroalkyl-2-hydroxypropyl)-N,N′-diacetic acid ethylenediamine (2 edda, where n represents the number of carbon atoms in the fluorocarbon chain (4, 6, and 8)) were synthesized. In these present gemini surfactants, the relatively small carboxylic acid moieties form hydrophilic head groups. The surface properties or structures of the aggregates of these surfactants are strongly influenced by the nonflexible fluorocarbons and small head groups; this is because these surfactants have a closely packed molecular structure. The equilibrium surface tension properties of these surfactants were measured at 298.2 K for various fluorocarbon chain lengths. The plot of the logarithm of the critical micelle concentration (cmc) against the fluorocarbon chain lengths for 2 edda (n = 4, 6, and 8) showed a minimum for n = 6. Furthermore, the lowest surface tension of 2 edda at the cmc was 16.4 mN m−1. Such unique behavior has not been observed even in the other fluorinated surfactants. Changes in the shapes and sizes of these surfactant aggregate with concentration were investigated by dynamic light scattering and transmission electron microscopy (TEM). The TEM micrographs showed that in an aqueous alkali solution, 2 edda mainly formed aggregates with stringlike (n = 4), cagelike (n = 6), and distorted bilayer structures (n = 8). The morphological changes in the aggregates were affected by the molecular structure composed of nonflexible fluorocarbon chains and flexible hydrocarbon chains. 相似文献
867.
Ken Hatano Hitoshi Saeki Hiroo Yokota Hiroaki Aizawa Tetsuo Koyama Koji Matsuoka Daiyo Terunuma 《Tetrahedron letters》2009,50(42):28-2381
A glycocluster peripherally functionalized with a lactose (Lac: Galβ1→4Glcβ1–) derivative possessing a silole moiety as a luminophore was synthesized. The photoluminescence spectrum of the glycocluster showed extremely strong emission at 474 nm and the absolute quantum yield was estimated to be 92% in distilled water. The emission intensity was decreased by increasing the amount of peanut agglutinin (PNA), a lactose-binding lectin, and plots of the relative fluorescence intensity revealed a decline of 95% in emission intensity. Fluorescence quenching of the glycocluster upon mixing with PNA could be easily observed by the naked eye under UV irradiation, whereas no distinct change in fluorescence properties of the glycocluster was observed when wheat germ agglutinin (WGA) was employed. 相似文献
868.
Vukovi? J Matsuoka S Yoshimura K Juri?i? Grube?i? R Kremer D ?anti? N 《Analytical sciences》2012,28(4):397-402
A very sensitive, simple, and fast solid-phase spectrophotometric procedure for the determination of phenol using the p-nitrobenzenediazonium reagent (DAR reagent) was developed. This procedure is based on the simultaneous concentration of the orange product on a Dowex 1-X2 anion exchanger within 15 min, and a direct absorbance measurement of the sorbed species at both 530 nm (the absorption maximum of the phenol-DAR in the resin phase) and 700 nm (the range where only the resin absorbs light). Quality control and evaluation of the analytical parameters was carried out using a comprehensive prevalidation strategy. The linearity of the method was confirmed within an analyte working range from 0.01 to 0.10 μmol (0.2 to 2.0 nmol mL(-1)). The precision ranged from ±1.17 to ±9.61%; the accuracy ranged from -17.50 to +17.81%. The evaluated limiting values were L(D) = 0.0013 μmol and L(Q) = 0.0082 μmol. The DAR-SPS method was successfully applied to the determination of phenol in a pharmaceutical sample of salicylic acid (98.0-100.0%) and vaccines (98.0-103.4%). 相似文献
869.
A novel method for the selective determination of Fe(II) and Fe(III) in water using 2-nitroso-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (PSAP) was developed. QAE-Sephadex anion exchanger packed in a flow-through cell was used as a medium not only for both the concentration and the spectrophotometric measurements of the Fe-PSAP complex, but also for reduction of the Fe(III)-PSAP complex. The PSAP complex of Fe(II) or Fe(III) was strongly adsorbed on the anion exchanger in a weakly acidic to weakly basic region, but the Fe(III) complex was readily and completely reduced to the Fe(II) complex only in a neutral to weakly alkaline region in the solid phase. These properties were utilized to determine the Fe(II) and total Fe concentration without the addition of any reducing agent. The detection limits (3σ) were 0.18 ng for Fe(II) and 0.18 ng for total Fe using a 3.2-cm(3) sample solution. The present method is applicable to the determination of dissolved iron species present at μg dm(-3) levels in natural water samples. 相似文献
870.
Depending on the N-heterocyclic carbene catalyst utilized, α-unbranched aldehydes selectively provided amides, esters, or carboxylic acids through oxidation by NCS. The α-unbranched aldehyde underwent these reactions chemoselectively in the presence of an aromatic or α-branched aldehyde. 相似文献