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排序方式: 共有398条查询结果,搜索用时 156 毫秒
41.
The growth of C60 nanowhiskers (C60NWs) prepared by a modified liquid–liquid interfacial precipitation method is investigated, focusing on the effect of solvent ratio and water content in the C60–toluene–isopropyl alcohol (IPA) solution system. The precipitation of C60NWs was markedly influenced by the solvent ratio of toluene to IPA, and the C60NWs were found to grow longer above a critical diameter (Dc), which depends on the solvent ratio. The addition of a small amount of H2O to the C60–toluene–IPA solution promoted the growth of C60NWs. This catalytic effect of water on the growth of C60NWs was confirmed also by the experiment using heavy water (D2O) and by the decrease of growth activation energy of C60NWs with increase of H2O content in the C60–toluene–IPA solution. 相似文献
42.
Masako Maekawa Haruko Nagai Kayoko Magara 《Colloids and surfaces. A, Physicochemical and engineering aspects》2000,170(2-3):191-198
Mixture diffusion of two dyes (C.I. Direct Blue 15 (DB15) and C.I. Direct Yellow 12 (DY12)) with different affinity onto the substrate into cellulose membrane from the binary solution was studied at 55°C. Uptake curves and concentration–distance profiles were measured experimentally in the ratios (DB15:DY12) 1:0.5, 1:1 and 1:2. It was examined whether the diffusion of the dyes could be analyzed based on the parallel diffusion theory of surface and pore diffusion. It was revealed that the diffusion of DB15 with higher affinity could be analyzed based on the model in the ratios 1:0.5 and 1:1, although the theoretical value deviated slightly from the data in the concentration–distance profile in the ratio 1:1. On the other hand, the diffusion of DY12 with smaller affinity could not be described by the model, because the diffusivity of the dye changed during the adsorption process against the assumption of the model. 相似文献
43.
Nonlinear processes in UV optical materials were investigated by using 280-fs, 248-nm pulses. Nonlinear absorption in CaF2 was confirmed to be a two-photon process by using the luminescence of self-trapped excitons, which was also used for the single shot pulse width measurement. The absorption bands due to F centers were identified in CaF2, MgF2, and LiF after several hundred shots at 100 GW/cm2. Absorption at 248 nm was considerable especially in MgF2 and LiF. Self-focusing and self-phase modulation were observed in CaF2. 相似文献
44.
45.
Noriko Hata Shiho Hieda Mika Yamada Rie Yasui Hideki Kuramitz Shigeru Taguchi 《Analytical sciences》2008,24(7):925-928
The formation of a liquid organic ion associate in an aqueous sample was applied to the concentration and determination of cadmium in environmental water samples. Cadmium was converted into a complex with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol (5-Br-PAPS) in a 40-mL sample solution, and was extracted into a liquid ion associate of phenolsulfonate and benzethonium during phase formation. More than 400-fold enrichment was easily attained by this technique, because the volume of the liquid organic phase formed was very small, ca. 2 microL. After dilution of the organic phase with a small volume of 2-methoxyethanol, the cadmium in the solution was determined by GF-AAS. The detection limit was 0.09 ng/L (3sigma(b)). This method was applied to the determination of cadmium in river water and seawater. 相似文献
46.
Potentiometric and spectrophotometric flow-injection determinations of metal ions, based on metal ion buffers, are described. A copper(II) ion-selective electrode and copper(II) ion buffers containing nitrilotriacetic acid (NTA) or ethylenebis(oxyethylenedinitrilo)tetraacetic acid (EGTA) are used for determination of ca. 10?3 M transition metal ions or of calcium in the presence of magnesium. Spectrophotometric determination of transition metal ions is achieved by using a zinc ion buffer solution containing NTA and xylenol orange as indicator. Zinc concentrations up to 2 M can be determined by using large dispersion in the manifold. The factors influencing the sensitivity of the proposed methods are discussed. 相似文献
47.
Dr. Toru Amaya Dai Hata Dr. Toshiyuki Moriuchi Prof. Dr. Toshikazu Hirao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16427-16433
A reduced form of polyaniline has been shown to induce direct arylation of an arenediazonium salt with an arene (Gomberg–Bachmann reaction) to give the cross‐coupling product in moderate to good yields under mild conditions. Various arenediazonium salts and arenes, including heteroarenes such as furans, thiophenes, and pyrroles, are employed for the reaction. The most favorable combination of substrates is an electron‐poor arenediazonium salt with an electron‐rich heteroarene. Investigation of the mechanism by reactions with radical scavengers and experiments on kinetic isotope effects indicated the occurrence of a radical chain reaction initiated by one‐electron reduction of an arenediazonium salt by the polyaniline. Only 1 mol % (based on aniline tetramer) of the polyaniline is required for the cross‐coupling reaction to occur. This reaction proceeds under metal‐free conditions and with no need for photonic activation. 相似文献
48.
Axisymmetric problem of a nonhomogeneous elastic layer 总被引:3,自引:0,他引:3
Summary The paper deals with a theoretical treatment of elastic behavior for a medium with nonhomogeneous materials property, which
is defined by the relation , i.e., shear modulus of elasticity G varies with the dimensionless axial coordinate by the power product form, arbitrarily. Fundamental differential equation for such nonhomogeneous medium has been already
proposed in [5]. It is given by a second-order partial differential equation. However, it was found that the fundamental equation
is not sufficient in general to solve several kinds of boundary-value problems. On the other hand, it is shown in the present
paper making use of the fundamental equations system for a nonhomogeneous medium, which has been proposed in our previous
paper [7], it is possible to solve axisymmetric problems for a thick plate (layer) subjected to an arbitrarily distributed
load or a concentrated load on its surfaces. Numerical calculations are carried out for several cases, taking into account
the variation of the nonhomogeneous parameter m. The numerical results for displacements stress and components are shown in graphical form.
Accepted for publication 25 March 1997 相似文献
49.
Motoyama Y Sakakura T Takemoto T Shimozono K Aoki K Nishiyama H 《Molecules (Basel, Switzerland)》2011,16(7):5387-5401
Bis(oxazolinyl)phenylrhodium(III) aqua complexes, (Phebox)RhX?(H?O) [X = Cl, Br], were found to be efficient Lewis acid catalysts for the enantioselective addition of allyl- and methallyltributyltin reagents to amino aldehydes. The reactions proceed smoothly in the presence of 5-10 mol % of (Phebox)RhX?(H?O) complex at ambient temperature to give the corresponding amino alcohols with modest to good enantioselectivity (up to 94% ee). 相似文献
50.
Minakata K Nozawa H Gonmori K Yamagishi I Suzuki M Hasegawa K Watanabe K Suzuki O 《Analytical and bioanalytical chemistry》2011,400(7):1945-1951
An electrospray ionization tandem mass spectrometric (ESI-MS-MS) method has been developed for the determination of cyanide
(CN–) in blood. Five microliters of blood was hemolyzed with 50 μL of water, then 5 μL of 1 M tetramethylammonium hydroxide solution
was added to raise the pH of the hemolysate and to liberate CN– from methemoglobin. CN– was then reacted with NaAuCl4 to produce dicyanogold, Au(CN)2–, that was extracted with 75 μL of methyl isobutyl ketone. Ten microliters of the extract was injected directly into an ESI-MS-MS
instrument and quantification of CN– was performed by selected reaction monitoring of the product ion CN– at m/z 26, derived from the precursor ion Au(CN)2– at m/z 249. CN– could be measured in the quantification range of 2.60 to 260 μg/L with the limit of detection at 0.56 μg/L in blood. This
method was applied to the analysis of clinical samples and the concentrations of CN– in the blood were as follows: 7.13 ± 2.41 μg/L for six healthy non-smokers, 3.08 ± 1.12 μg/L for six CO gas victims, 730 ± 867 μg
for 21 house fire victims, and 3,030 ± 97 μg/L for a victim who ingested NaCN. The increase of CN– in the blood of a victim who ingested NaN3 was confirmed using MS-MS for the first time, and the concentrations of CN– in the blood, gastric content and urine were 78.5 ± 5.5, 11.8 ± 0.5, and 11.4 ± 0.8 μg/L, respectively. 相似文献