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991.
S.K. Arora Vipul Patel R.G. Patel Brijesh Amin Anjana Kothari 《Journal of Physics and Chemistry of Solids》2004,65(5):965-973
The a.c. and d.c. conductivity of SrC4H4O6·3H2O are measured and are found to lie between usual conductivities of semiconductor and insulator. Temperature dependence of d.c. conductivity shows intrinsic conduction, which is confirmed by the slope of versus data. Due to application of thermal energy, noticeable conductivity peaks imply liberation of water molecules during dehydration and the formation of strontium oxalate. The conductivity plot has a nature similar to the intrinsic-to-extrinsic transition found in normal semiconductors. There occurs Efros hopping conduction in our samples. 相似文献
992.
Subhabrata Chaudhury Dennis W. Bennett Tasneem A. Siddiquee 《Journal of organometallic chemistry》2004,689(9):1437-1443
Tricarbonyl(1-methoxycarbonyl-5-phenylpentadienyl)iron(1+) hexafluorophosphate (7) was prepared in two steps from tricarbonyl(methyl 6-oxo-2,4-hexadienoate)iron. While addition of carbon and heteroatom nucleophiles to 7 generally occurs at the phenyl-substituted dienyl carbon to afford (2,4-dienoate)iron products, the addition of phthalimide proceeded at C2 to afford a (pentenediyl)iron product (18). Complex 18 was structurally characterized by X-ray diffraction analysis. 相似文献
993.
G.?PolettiEmail author F.?Orsini A.?Raffaele-Addamo C.?Riccardi E.?Selli 《Pramana》2004,62(4):911-921
Some selective cold plasma processing modify specific surface properties of textile polymeric materials such as their dyeability,
wettability and hydrorepellence. To correlate the sample surface changes with the acquired surface properties allows one to
obtain information on the chemical and physical processing involved in plasma treatment. In this work, atomic force microscopy
(AFM) has been applied to investigate the morphological and topographical surface modifications induced by RF cold plasma
processing of poly(ethyleneterephthalate) (PET) fabrics. Rms surface roughness and surface area of the samples are measured
before and after the treatments. The morphology changes have been analysed as a function of the treatment time and air gas
pressure. Measurements have been performed also using plasmas produced by different gases such as He, Ar, SF6 and CF4. The PET shows different behaviour with different gas plasmas. In the case of air, He and Ar gases the sample surface modifications
seem to be mainly due to etching effects, while the fluorine atoms grafting probably is responsible for surface rearrangement
process using SF6 and CF4 gases. As a consequence different surface properties are produced in the plasma treated samples.
Article presented at the International Conference on the Frontiers of Plasma Physics and Technology, 9–14 December 2002, Bangalore,
India. 相似文献
994.
Anuradha?MishraEmail author Rajani?Srinivasan Malvika?Bajpai Rashmi?Dubey 《Colloid and polymer science》2004,282(7):722-727
The chemical modification of Plantago psyllium mucilage (Psy), an anionic polysaccharide, was done by grafting polyacrylamide (PAM) chains to prepare a graft-copolymer (Psy-g-PAM). It was synthesized in the presence of nitrogen using ceric ammonium nitrate–nitric acid redox initiator and characterized by IR spectroscopy, scanning electron microscopy and viscosity measurements. This grafted copolymer was tested for its flocculation efficiency in textile wastewater by the standard Jar test method. The effects of polymer concentration, pH and contact time on the percentage removal of solid wastes [total dissolved solids (TDS) and suspended solids (SS)] and color from textile effluent are reported. The optimum dose was found to be 1.6 mg l–1, at which maximum solid removal (SS and TDS) was seen. The most suitable pH for TDS and color removal was neutral (7.0) and for SS removal alkaline pH (9.2) was found to be most suitable. The optimum treatment duration for solid waste removal was 5 h. The X-ray diffraction analysis of Psy-g-PAM and solid waste before and after treatment suggests the interaction of the solid waste and Psy-g-PAM copolymer. 相似文献
995.
The influence of polymerization conditions on the morphology of thin films of poly-(N-methylaniline) (PNMA) was studied. The films were prepared by electropolymerization on gold and platinum electrodes and studied by optical and electron microscopy. It was demonstrated that the film morphology does not depend on the polymerization rate or on the electrode metal. However, it is sensitive to the kind of counter ion of PNMA. The polymers containing acetate or chloride do not form stable films. Polymer films containing phosphate or sulfate display inhomogeneous structures. A formation of sprouts and nanotubes was observed for PNMA sulfate. The films formed by PNMA perchlorate are smooth and transparent (glass-like structure). A sublayer of 4-aminothiophenol increases the adhesion of polymers to the gold surface. 相似文献
996.
Jie-Hui Yu Ling-Yun Pan Tie-Gang Wang Xiao-Bing Cui Yi-Zhi Li Tian-Hui Ma 《Journal of solid state chemistry》2003,175(2):152-158
The title compound [NiII(phen)3]2[Cu10H2I16] 1 (phen=1,10-phenanthroline, C12H8N2) was hydrothermally synthesized from a simple reaction of CuI-NiCl2·6H2O-phen·H2O-H2O. X-ray analysis revealed that it consists of NiN62+ core cation and decanuclear iodocuprate(I) anion together with two dissociative H+ ions. In anionic unit, the discrete decanuclear iodocuprate(I) is formed by crystallographically independent five monovalent copper atoms and eight iodine atoms via an inversion center. There exist two types of Cu(I) coordination sites; only one copper(I) atom is in a highly distorted triangular planar site, and the other four copper(I) atoms display the tetrahedral geometries. It deserves to be noted that four types of bridging modes of I− ions in which two are ordinary μ2- and μ3-bonding modes can be found. But the other two are the rectangle planar geometry and the novel μ4-bridge like an “umbrella”, and both of them are rather rare in the halocuprates(I). Compound 1 was crystallized in triclinic space group with a=11.6861(17), b=14.590(2), c=14.649(2) Å, α=76.370(2), β=70.830(2), γ=81.320(3)o, R=0.075, and was characterized by elemental analysis, IR spectrum and UV-VIS spectrum. The third-order non-linear optical property of 1 was also investigated and the compound exhibits the reverse saturable absorption and self-defocusing performance. 相似文献
997.
Cooley NM Higgins JT Holmes MG Attridge TH 《Journal of photochemistry and photobiology. B, Biology》2001,60(2-3):143-150
The effects of supplementary ultraviolet-A (UV-A) and ultraviolet-B+A (UV-B+A) in the natural environment on the growth and morphology of various ecotypes of Arabidopsis thaliana were investigated. The ecotypes investigated were Columbia (Col-4), Landsberg erecta (Ler-0), Cvi-0, Wassilewskija, Enkheim-D, Aa-0 and Di-1. The mutant hy-4 was also used. Results varied with the radiation treatment, ecotype and parameter measured. Plants subjected to elevated UV-A were both insensitive (all parameters Cvi-0 and Col-4) and sensitive. When responses to UV-A occurred they were mostly inhibitory (all significant responses of Di-1 and Enkheim-D, most parameters of Wassilewskija, and some parameters of hy-4), however, promotive affects were observed for some parameters of Aa-0 and Ler-0. Supplementary UV-B+A inhibited all parameters of Di-1 and Enkheim-D and most parameters of Col-4, Ler-0 and hy-4, but Wassilewskija, Aa-0 and Cvi-0 were mostly insensitive. The magnitude of the UV-B+A response varied with ecotype (compare Di-1 with Ler-0). Some ecotypes were sensitive to UV-A but not UV-B+A (Aa-0), whereas others (Ler-0, Col-4) show the opposite sensitivities. A linear relationship is reported between the degree of UV-B+A inhibition of each ecotype and growth rate. The higher the growth rate the more susceptible the ecotype is to UV-B+A inhibition. This relationship holds for the majority of growth parameters measured. 相似文献
998.
M.?BestehornEmail author A.?Pototsky U.?Thiele 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(4):457-467
We study large scale surface deformations of a liquid film
unstable due to the Marangoni effect caused by external heating
on a smooth and solid substrate. The work is based on the thin
film equation which can be derived from the basic hydrodynamic
equations. To prevent rupture, a repelling disjoining pressure
is included which accounts for the stabilization of a thin
precursor film and so prevents the occurrence of completely dry
regions. Linear stability analysis, nonlinear stationary
solutions, as well as three-dimensional time dependent numerical
solutions for horizontal and inclined substrates reveal a rich
scenario of possible structures for several realistic fluid
parameters. 相似文献
999.
Characterisation of precipitate phases in magnesium alloys using electron microdiffraction 总被引:1,自引:0,他引:1
Recent results of the characterisation of the structure, morphology and orientation of fine-scale, strengthening precipitate phases in selected magnesium alloys using transmission electron microscopy and microdiffraction are reviewed. The strengthening precipitate phases in Mg–Y–Nd alloys, aged to maximum hardness at 250°C, have been found to include two metastable precipitate phases β′ and β1, and the equilibrium precipitate β. The β′ phase has a globular form, a base-centred orthorhombic structure (potential point group of mmm), and an orientation relationship such that (100)β′//(1
10)α, [001]β′//[0001]α. The β1 phase has an f.c.c. structure (space group
and an orientation relationship that may be described by
(100)β1//[0001]α, and forms as plates parallel to
The β phase has an f.c.c. structure (space group
) and also forms as plates on
with an orientation relationship with the matrix phase that is identical to that observed for β1 phase. Precipitates in Mg–Al alloys, aged isothermally at 200°C, invariably have the b.c.c. structure of the equilibrium precipitate phase β (Mg17Al12). Three orientation relationships have been observed between β and the matrix phase. Most precipitates have an irrational orientation relationship that approximates to the Burger's relationship, (001)β//(0001)α,
and a faceted lath morphology with habit plane parallel to (0001)α. A minor fraction of precipitates posses an orientation relationship that is of the form
and have a prismatic rod morphology. The long axes of these rods are parallel to [0001]α, and their faceted surfaces are parallel to
A few precipitates are observed to have an orientation relationship such that
and a rod shape, with their long axes apparently inclined with respect to [0001]α. 相似文献
Full-size image
Full-size image
1000.
Ab initio molecular orbital calculations (Hartree–Fock, HF and density functional theories, DFTs) have been carried out for SiO2 polymorphs coesite, low cristobalite, and -quartz, in order to investigate the reliability of this method for predicting 29Si and 17O nuclear magnetic resonance (NMR) properties of silicates. Oxygen- and silicon-centered clusters consisting of one (1T) to three tetrahedral (3T) shells (one to four atomic shells), taken from real crystal structure, have been investigated. It is found that for reasonable predication of both the 29Si and 17O chemical shifts (δiSi and δiO), the minimum cluster is one that gives the correct second neighbors to the nucleus of interest. Both the δiSi and δiO have reached convergence with respect to cluster size at the OH-terminated two tetrahedral (2T) shell (three atomic shells around Si and four atomic shells around O) model. At convergence, the calculated δiSi values agree well (within ±1 ppm) with experimental data. The calculated 17O electric field gradient (EFG)-related parameters also agree with experimental data within experimental uncertainties. The calculation also reproduces small differences in δiO for O sites with similar tetrahedral connectivities, but shows deviations up to about 10 ppm in relative difference for O sites with different tetrahedral connectivities. The poor performance for the latter is mainly due to the approximations of the HF method. Our study thus suggests that the ab initio calculation method is a reliable mean for predicting 29Si and 17O NMR parameters for silicates. Such an approach should find application not only to well-ordered crystalline phases, but also to disordered materials, by combining with other techniques, such as the molecular dynamics simulation method. 相似文献