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81.
Single crystalline , (Tz*)– = 1,2,3‐triazolate anion, C2H2N3–, was obtained by the reaction of terbium metal with the amine 1H‐1,2,3‐triazole. As no additional solvent was used, the formation of a homoleptic framework without additional co‐ligands is accessible. Furthermore molecular hydrogen is produced. is a 2‐dimensional framework with a (6,6) topology including (Tz*)– double bridges. The structure can be deduced from a basic structure type as it adopts the AlCl3 structure with the triazolate ligands establishing the package. (Tz*)– thus function as μ‐η1:η2/μ‐η2:η1 linkers between trivalent terbium ions that have a C.N. of nine. The framework exhibits an exceptional thermal stability up to 380 °C considering the three neighbouring nitrogen atoms of the triazolate ligands. At this point the framework decomposes in one single exothermic step under release of N2. 相似文献
82.
Anke Sterzik Helmar Görls Eike T. Spielberg Winfried Plass Wolfgang Imhof PD Dr. 《无机化学与普通化学杂志》2009,635(11):1594-1599
The tetranuclear compound [Mo2(O2C‐tBu)3]2(μ‐C2O4) ( 1 ) that is prepared from [Mo2(O2C‐tBu)3]4 and oxalic acid, was reacted with MnI2 · 2THF to form the polyoxomolybdate compound [Mn(CH3OH)6] [Mo8O16(OCH3)8(C2O4)] ( 2 ) in a complex redox reaction. Crystals of 2 were analyzed by single‐crystal X‐ray diffraction showing a octanuclear polyoxomolybdate dianion in which the Mo=O moieties are alternately connected through μ‐oxo and μ‐methoxo units. Charge balance in 2 is realized by a manganese(II) cation that is octahedrally coordinated by methanol ligands. The crystal structure is dominated by strong hydrogen bond interactions of the O–H ··· O type of methanol molecules coordinated to manganese as well as additional methanol molecules in the crystal lattice. 相似文献
83.
Holger Kohlmann PD Dr. Nadine Kurtzemann Richard Weihrich Thomas Hansen 《无机化学与普通化学杂志》2009,635(15):2399-2405
A novel gas pressure cell for in situ neutron powder diffraction has been developed. It is based on a single crystal sapphire tube as a sample holder, allows a 360° unobstructed access by the neutron beam and has little background contribution. This device was used to study the hydrogenation of α‐MgPd3, which undergoes a hydrogen driven rearrangement from a ZrAl3 to a AuCu3 type structure. Deuterium could be located and a strong preference of [Pd6] voids was found in α‐MgPd3D0.79 under 5 bar and in α‐MgPd3D0.94 under 20 bar deuterium pressure. The crystal structure may be described as a new defect superstructure variant of the NaCl type. In situ thermal analysis under 5 bar hydrogen pressure showed that both the hydrogen uptake of α‐MgPd3, which is complete at temperatures below 450 K, and the transformation to the hydride of cubic β‐MgPd3, starting around 550 K, are exothermic. This completion of the hydrogenation‐dehydrogenation series of MgPd3 suggests, that the rearrangement of the metal structure proceeds by a hydrogen assisted gliding mechanism with a shift vector of [110]. This is also supported by quantum chemical calculations, which show a decohesion of the intermetallic structure upon hydrogenation accompanied by the appearance of Pd–H bonding interactions. 相似文献
84.
PD Dr. Holger Kohlmann 《无机化学与普通化学杂志》2010,636(11):2046-2046
85.
PD Dr. Thomas G. Mayerhöfer Dr. Andrei V. Pipa Prof. Dr. Jürgen Popp 《Chemphyschem》2019,20(21):2748-2753
As derived by Max Planck in 1903 from dispersion theory, Beer's law has a fundamental limitation. The concentration dependence of absorbance can deviate from linearity, even in the absence of any interactions or instrumental nonlinearities. Integrated absorbance, not peak absorbance, depends linearly on concentration. The numerical integration of the absorbance leads to maximum deviations from linearity of less than 0.1 %. This deviation is a consequence of a sum rule that was derived from the Kramers-Kronig relations at a time when the fundamental limitation of Beer's law was no longer mentioned in the literature. This sum rule also links concentration to (classical) oscillator strengths and thereby enables the use of dispersion analysis to determine the concentration directly from transmittance and reflectance measurements. Thus, concentration analysis of complex samples, such as layered and/or anisotropic materials, in which Beer's law cannot be applied, can be achieved using dispersion analysis. 相似文献
86.
Stephan Berner Andreas B. Schmidt Mirko Zimmermann Dr. Andrey N. Pravdivtsev Dr. Stefan Glöggler Prof. Dr. Dr. h.c. Jürgen Hennig PD Dr. Dominik von Elverfeldt Prof. Dr. Jan-Bernd Hövener 《ChemistryOpen》2019,8(6):728-736
The signal enhancement provided by the hyperpolarization of nuclear spins of biological molecules is a highly promising technique for diagnostic imaging. To date, most 13C-contrast agents had to be polarized in an extra, complex or cost intensive polarizer. Recently, the in situ hyperpolarization of a 13C contrast agent to >20 % was demonstrated without a polarizer but within the bore of an MRI system. This approach addresses some of the challenges of MRI with hyperpolarized tracers, i. e. elevated cost, long production times, and loss of polarization during transfer to the detection site. Here, we demonstrate the first hyperpolarization of a biomolecule in aqueous solution in the bore of an MRI at field strength of 7 T within seconds. The 13C nucleus of 1-13C, 2,3-2H2-succinate was polarized to 11 % corresponding to a signal enhancement of approximately 18.000. Interesting effects during the process of the hydrogenation reaction which lead to a significant loss of polarization have been observed. 相似文献
87.
PD Dr. O. Müller 《Mathematical Methods of Operations Research》1972,16(2):B7-B16
Zusammenfassung Die Fallstudie behandelt das Problem der Dimensionierung der verschiedenen Teile einer sehr komplexen Anlage für mehrstufige Produktion. Die Programmierung erfolgte in FORTRAN. Anhand der Fallstudie werden einige wesentliche Punkte herausgearbeitet, die für den Erfolg von Simulationsprojekten wesentlich sind, nämlich: klare Zielsetzung, Simulation von Teilbereichen, so daß in kürzester Zeit Resultate vorliegen.
Summary The case-study deals with the problem of the size of various parts of a very complex plant lay-out for multi-step production. The programming was done in FORTAN. Based on the case-study a few points were worked out which are essential for the success of simulation-projects, to wit: clear statement of purpose; simulation of partial scopes, which produce short-term results.相似文献
88.
89.
Zusammenfassung B?ndchenf?rmige Proben ergeben bei Kaltverstrekkung mit ausgepr?gter Einschnürzone (heterogene Kaltverstreckung) Querschnittsformen,
die am Rand dicker als in der Mitte sind und an den R?ndern h?here Orientierungsgrade aufweisen. Verstreckungen ohne Einschnürung
ergeben fast gleichm?\ige Dicke (bis auf die Abrundung der Kanten) quer zur Verstreckungsrichtung und keine merkbaren Unterschiede
im Orientierungsgrad. Die Erscheinung ist im Prinzip aus der Art des Abflie\ens des Materials vom unverstreckten Teil über
die Flie\zone ins Verstreckte verst?ndlich.
Der Deutschen Forschungsgemeinschaft und dem Fonds der Chemischen Industrie sei auch an dieser Stelle Dank für die laufende
Unterstützung unserer Forschungen ausgesprochen. 相似文献
90.