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31.
Monika Schuster Robert Inführ Claudia Turecek Jürgen Stampfl Franz Varga Robert Liska 《Monatshefte für Chemie / Chemical Monthly》2006,137(7):843-853
Summary. To substitute cross-linked photopolymers in rapid prototyping of mold materials and therefore extend the range of materials
which can be casted, organo-soluble photopolymers were developed. Branched bisalkylacrylamides were suitable as base component
for such formulations, due to their high reactivity, good mechanical properties, and excellent solubility of the formed polymers.
These molding materials were used to prepare cellular biocompatible materials which could be used as bone replacement materials.
Biocompatible crosslinkers based on methacrylates from hydrolyzed gelatine or lactic acid ethyleneglycol blockcopolymers and
commercially available reactive diluents are the base components of such a formulation. Biocompatibility was investigated
by osteoblast-like cells. Cellular biocompatible parts were obtained by thermal polymerization in soluble mould materials
prepared by 3D-photoshaping. 相似文献
32.
E. Schuster und K. Wohlleben 《Fresenius' Journal of Analytical Chemistry》1969,245(4):239-244
Zusammenfassung Elemente mit niedriger Kernladungszahl lassen sich durch Aktivierung mit thermischen Neutronen entweder überhaupt nicht oder nur mit sehr geringer Empfindlichkeit bestimmen.In den letzten Jahren gewinnt daher die Bestrahlung mit Ionen (Protonen, Deuteronen, Tritium-, 3He- und 4He-Ionen) zur Aktivierungsanalyse der leichten Elemente zunehmend an Bedeutung. Zwischen Ionen- und Neutronenaktivierungen bestehen prinzipielle Unterschiede, die diskutiert werden.Aufgrund ihrer relativ geringen Reichweite in Materie eignen sich Ionen besonders zur Untersuchung von Oberflächen sowie dünnen Aufdampfschichten und Korrosionsschichten. Da die Aktivierungstiefe durch entsprechende Wahl der Versuchsparameter festgelegt werden kann, laßt sich auch die Tiefenverteilung von Fremdstoffen im Matrixmaterial untersuchen.Zur Bestimmung von Sauerstoff, Stickstoff und Kohlenstoff werden Protonen- und Deuteronenreaktionen herangezogen; aber auch Elemente wie Bor und Aluminium lassen sich dureh Ionenaktivierung erfassen. Bei einer Einschußenergie der Ionen von 3,0 MeV, einer Flußdichte von 5 A/cm2 und einer Bestrahlungszeit, die der Halbwertszeit des zu aktivierenden Elementes entspricht, liegt die Bestimmungsempfindlichkeit für die genannten Elemente im Bereich von 1–100 ppb.Über die Bestimmung von Kohlenstoff in Silicium und Sauerstoff in aufgedampften Selenschichten wird berichtet.
Vortrag bei der Tagung Analytische Probleme der Reindarstellung von Halbleitern, Wiesbaden, 24.–25. 9. 1968.
Herrn Prof. Dr. W. Gebauhr danken wir für viele anregende Diskussionen. Für die Mithilfe bei der Bestrahlung und Auswertung sind wir Frau K. Appler, Frl. E. Lüders und Herrn H. Pfann zu Dank verpflichtet. 相似文献
Determination of light elements in silicon and selenium by ion-activation analysis
Elements with low atomic number either cannot be determined at all by activation with thermal neutrons or only with very poor detection limit.In recent years, irradiation with ions (protons, deuterons, tritium ions, 3He- and 4He-ions) for activation analysis of the light elements has therefore gained increasing importance. There are basic differences between ion and neutron activation, which are discussed.Because of their relatively small range in matter, ions are particularly suited for analyzing surfaces as well as thin deposited films and corrosion layers. Since the activation depth can be established in advance by appropriate selection of the analysis parameters, the distribution of foreign matter in the matrix material can also be analyzed.Proton and deuteron reactions are employed to determine the presence of oxygen, nitrogen and carbon, but other elements such as boron and aluminium can also be detected by ion activation. The detection limit attained in analyzing the elements mentioned is within the range of 1 to 100 ppb with an ion bombarding energy of 3.0 MeV, a flux density of 5 A/cm2 and an irradiation period which corresponds to the half-life of the element to be activated.A report is given on the determination of carbon in silicon and oxygen in thin-deposited selenium films and the results are discussed.
Vortrag bei der Tagung Analytische Probleme der Reindarstellung von Halbleitern, Wiesbaden, 24.–25. 9. 1968.
Herrn Prof. Dr. W. Gebauhr danken wir für viele anregende Diskussionen. Für die Mithilfe bei der Bestrahlung und Auswertung sind wir Frau K. Appler, Frl. E. Lüders und Herrn H. Pfann zu Dank verpflichtet. 相似文献
33.
34.
The fluorescence peak of isoquinoline increases strongly in intensity with increasing pressure in polymethylmethacrylate (PMMA) and in polyisobutylene (PIB). In polyvinylalcohol the intensity decreases as the pressure increases. In all three cases the emission peak shifts to lower energy as the pressure increases. The results are consistent with the hypothesis that the ππ* state lies higher in energy than the nπ* state in non-hydrogen bonding solvents, but that the situation is reversed in hydrogen bonding solvents. 相似文献
35.
Ernst Berger David W. T. Griffith Gerhard Schuster Stephen R. Wilson 《Mikrochimica acta》1988,95(1-6):239-241
The use of an integrating sphere for the measurement of absorption spectra of thin films is described. The thin film (for example a rare gas matrix) is grown directly on the inside surface of the sphere. Multiple reflections inside the integrating sphere lead to significant enhancement of weak absorptions of the film, increasing the sensitivity of such measurements. 相似文献
36.
Potential curves for proton transfer in [H5O2]+ and for the dissociation of one OH bond in [H3O]+ were calculated by both ab initio and semi-empirical LCAO MO SCF CI methods. The energy barrier of the symmetric double minimum potential in [H5O2]+ is very sensitive to electron correlation. At an OO distance of 2.74 Å it decreases from the HF value of 9.5 kcal/mole to about 7.0 kcal/mole. The results of the semi-empirical calculations agree well with the ab initio data as long as only relative effects are regarded. The partitioning of correlation energy into contributions of individual electron pairs is very similar for proton transfer in [H5O2]+ and for the dissociation of one OH bond in [H3O]+. In this example the proton transfer appears as a superposition of two “contracted ionic dissociation” processes. An interpretation of the behaviour of correlation during these processes is presented. 相似文献
37.
Ab initio calculations on formaldehyde/Li+ complexes are presented. The most stable arrangement is characterized by an energy of interaction of 43.2 kcal/mole, C2v symmetry and an oxygen—lithium distance of ROLi = 1.77 Å. A detailed analysis of the electron density function gives proof of the electrostatic nature of the complexes H2O/Li+ and H2Co/Li+ and shows extensive mutual polarization. The failure of the semi-empirical method to predict the changes in electron density at the Li+ cation correctly is explained. 相似文献
38.
New Ternary Clathrate Compounds in the Systems Barium–Indium/Zinc/Cadmium–Germanium: Zintl Compounds with Phase Width? By systematic investigations in the systems barium–indium/zinc/cadmium–germanium we found a couple of new electrovalent ternary compounds with A8X46 clathrate (I) type structures. They crystallize cubically in space-group Pm3n. For Ba8In16Ge30 (a = 1 075.8 pm), Ba8Zn8Ge38 (a = 1 082.0 pm) and Ba8Cd8Ge38 (a = 1 096.0 pm) the structures were verified by X-ray single crystal diffraction data. According to valence and bounding distances the new clathrates should be Zintl compounds. Measurements of the temperature dependence of the electrical resistivity proved, that they are indeed semiconductors. A part of the 2B/3B metal atoms can be substituted by germanium. Charge balance will be retained by creation of vacancies in the A8X46 type structures. By phase analysis the limits of the composition range were determined as Ba8In4Ge9[]3Ge30 (a = 1 084.9 pm), Ba8Zn4Ge10[]2Ge30 (a = 1 073.6 pm) and Ba8Cd4Ge10[]2Ge30 (a = 1 082.0 pm). 相似文献
39.
A series of isomers of bis(N-methylpyrrolidine)-C(60) 2 (Prato bisadducts) was prepared by the 1,3-dipolar cycloaddition of N-methylazomethine ylide to C(60). Six isomers were separated and characterized by ESI-MS, UV/vis, and (1)H and (13)C NMR spectroscopy. The structures of these bisadducts were assigned based on (1) comparison of their molecular symmetries with their (1)H and (13)C NMR spectra, (2) comparison of their UV/vis spectra with those of corresponding Bingel-Hirsch bisadducts, and (3) the order of deshielding of the methylene and N-methyl (1)H NMR resonances. Prato bisaddition is less chemoselective than Bingel-Hirsch bisaddition to C(60). 相似文献
40.
New Ternary Phosphides and Arsenides of Cesium and Element of the 8th Transition Metal Group In the ternary systems Cesium/8th transition metal group/5th main group some new compounds were found and investigated. By single crystal measurements CsRh2P2 was found to crystallize in the space group 14/mmm with the lattice constants a = 390.11 pm and c = 1429.36 pm. The new compounds with the formula CsM2X2 (M = Fe, Co, Ru, Rh, Ir; X = P or As) crystallize in the ThCr2Si2-type structure, compounds of the formula Cs2MX2 (M = Ni, Pd, Pt; X = P or As) can be placed in a line with the K2PdP2-type structure. 相似文献