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101.
Iron-silicon thin films have been characterized by means of analytical transmission electron microscopic methods. Under certain conditions — composition and annealing temperature — these films exhibit thermoelectric behavior. In particular, the morphology and phase formation which results from annealing of these films, and doping with oxygen and nitrogen, are of interest. The thermoelectric phase -FeSi2 is formed at temperatures above 500°C. This phase is transformed into electrically conducting phases at about 1000°C. A small oxygen content does not influence this crystallization process. If the oxygen content is higher than 15 atom-% the electrically conducting phases exist even at 500°C. The presence of a small nitrogen content inhibits the formation of the -FeSi2 phase. The development of silicon and iron nitrides is possible. 相似文献
102.
Hans‐Jürgen Holdt Holger Müller Alexandra Kelling Hans‐Joachim Drexler Thomas Müller Thomas Schwarze Uwe Schilde Ines Starke 《无机化学与普通化学杂志》2006,632(1):114-122
Mercury(II) Chloride and Iodide Complexes of Dithia‐ and Tetrathiacrown Ethers The complexes [(HgCl2)2((ch)230S4O6)] ( 1 ), [HgCl2(mn21S2O5)] ( 2 ), [HgCl2(ch18S2O4)] ( 3 ) and [HgI(meb12S2O2)]2[Hg2I6] ( 4 ) have been synthesized, characterized and their crystal structures were determined. In [(HgCl2)2((ch)230S4O6)] two HgCl2 units are discretely bonded within the ligand cavity of the 30‐membered dichinoxaline‐tetrathia‐30‐crown‐10 ((ch)230S4O6) forming a binuclear complex. HgCl2 forms 1 : 1 “in‐cavity” complexes with the 21‐membered maleonitrile‐dithia‐21‐crown‐7 (mn21S2O5) ligand and the 18‐membered chinoxaline‐dithia‐18‐crown‐6 (ch18S2O4) ligand, respectively. The 12‐membered 4‐methyl‐benzo‐dithia‐12‐crown‐4 (meb12S2O2) ligand gave with two equivalents HgI2 the compound [HgI(meb12S2O2)]2[Hg2I6]. In the cation [HgI(meb12S2O2)]+ meb12S2O2 forms with the cation HgI+ a half‐sandwich complex. 相似文献
103.
Thermal degradation at 180° in air of PVC stabilized with an equimolar mixture of Ba and Cd stearates has been studied. The “unreacted” stearates were separated by filtering tetrahydrofuran solutions of samples. The filtration and thermal degradation were examined by means of infrared spectroscopy in the range 1400–1800 cm?1. It has been demonstrated that, during the thermal stress, CdCl2 is accumulated in the sample and that the presence of Ba stearate supports only the consumption of Cd stearate. 相似文献
104.
Ovcharenko VV Pihlaja K Stájer G 《Journal of the American Society for Mass Spectrometry》2003,14(9):1049-1056
The mass spectrometric behavior of stereo- and regioisomeric, partially saturated isoindoloquinazolines was studied by positive-ion electron ionization (EI) and fast-atom bombardment (FAB/LSIMS) mass spectrometry combined with collision-induced dissociation (CID). A highly stereospecific retro-Diels-Alder process was observed in the cyclohexene-fused isomers under the EI conditions, and a corresponding (although less specific) fragmentation was observed in their FAB spectra. In the absence of RDA fragmentations, regio- and stereoisomers of the cyclohexane-fused heterocycles could be distinguished based on their FAB/CID spectra. 相似文献
105.
Oxide ceramic masses react to simple shearing with hardening (peptisation: increase in the shear stress with the shear deformation).
In the present study the correlation between the increase in the shear stress and the porosity, agglomeration processes and
the type of flow are analysed. For this purpose oxide ceramic masses are tested in a shear device especially developed for
pastes and analysed by rheometric experiments, NMR methods and particle size analysis. The results support the hypothesis
that structural changes (hardening, increase in the mean porosity) of the material during the peptisation mainly depend on
the magnitude and not on the kind of the energy input and thus of the type of flow. The fraction of bound (more generally,
the immobilised) water increases with the shear displacement. Also crushing of primary particles could be observed. Both the
crushing of solid particles causing an increased solid surface and the formation of a three-dimensional gel structure are
microscopic effects capable of resulting in the binding or retaining water. On a macroscopic scale these phenomena cause hardening.
Magnetic resonance imaging visualises flow-induced agglomerates, which form owing to the shear flow and increase the porosity
averaged over the whole sample. After the shear experiment rolls of paste can be seen which indicate that the general assumption
of a plane shear flow in the shear device is not warrantable.
Received: 19 July 2001 Accepted: 25 October 2001 相似文献
106.
Joachim Meissner 《Polymer Testing》1983,3(4):291-301
Laser Doppler velocimetry (LDV) is a new tool for fluid dynamics studies. Using LDV the velocity vector field can be measured without disturbing the flow itself. However, in polymer melt fluid dynamics difficulties arise because of temperature problems, the relatively high pressure involved, and the often extremely slow flows. In this paper a LDV system is described which was set up especially for polymer melt flow investigations. 相似文献
107.
B.?Stark C.?Lach B.?Farago H.?Frey C.?Schlenk B.?StühnEmail author 《Colloid and polymer science》2003,281(7):593-600
A series of carbosilane dendrimers with perfluorinated end groups has been prepared. The structure of these molecules in dilute solution is studied using small angle neutron scattering. For generations g<3 we find a non-spherical shape of the particles and a tendency for aggregation. This result is supported by the analysis of the diffusion coefficient obtained from photon correlation spectroscopy. The overall shape of the molecules is that of a core-shell particle. The generation 4 molecule is obtained as a compact sphere. Neutron spin echo spectroscopy reveals a relaxation time which is attributed to the form fluctuations of this particle. 相似文献
108.
Electron micrographs of parallel arrays of negatively stained ramie cellulose protofibrils were analyzed using the two-dimensional digital autocorrelation function (ACF). The method is based upon the statistical analysis of images in real space. The ACF shows strong parallel streaks of high correlation, and the lateral distance between adjacent streaks allows the mean interfibrillar distance to be estimated as 3.7 nm. The intensity profile along the streaks shows a weak modulation with peaks occurring at integral multiples of 3 or 6 nm. These results provide direct evidence that there is a regular axial texture in the protofibrils, and corroborate the conclusions previously drawn from optical diffraction analysis. Using the difference vectors found in the ACF it has been possible to reduce the picture noise level by linear integration, thereby obtaining an enhanced image. A preliminary result obtained in this way suggests that the projected protofibril morphology associated with the observed axial periodicity is a ribbon-like zigzag structure. Possible applications of the method for future work are discussed. 相似文献
109.
A simple semiconductor gas sensor (TGS 812) is used for the on-line measurement and control of indole during the production of l-tryptophan from indole and l-serine with immobilized E. coli cells. Indole is estimated in the reactor gas space. In combination with an automatic indole supply system, a feed-batch process became possible. The indole concentration was monitored and kept within the optimal range (300–600 mg l?1). A simple gas-sensing electrode dipped in the reaction medium provides direct measurement of organic solvents and gases in the liquid. Such a system is suitable for on-line determination of ethanol (10–70 g l?1) during continuous production of ethanol with immobilized yeast cells. 相似文献
110.
M. Zieliński A. Zielińska H. Papiernik-Zielińska W. Städter M. Gehre G. Czarnota G. Kasprzyk 《Journal of Radioanalytical and Nuclear Chemistry》1995,191(2):369-380
Carbon-13 intramolecular kinetic isotope effects in the decarbonylation of oxalic acid dihydrate of natural isotopic composition by SO3 and by fuming sulphuric acid at room temperature and decarbonylation of oxalic acid dihydrate by 100% H3PO4 in the temperature interval 80–150°C have been determined. The obtained isotopic and kinetic results have been compared with the earlier13C experimental and theoretical studies in other solvents. 相似文献