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71.
Wolfgang Rother 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1988,39(3):334-350
Summary Following a suggestion of J. Goodisman, we substitute the therm
by
in the Thomas-Fermi-von Weizsäcker energy functional for atoms.f
z3 [0,1] is a function depending on the nuclear chargez.We establish conditions for the functionsf
z
such that the ratio of this modified TFW-energyE
kz
/TFWG
(z) (kz is the total number of electrons) and the exact quantum mechanical energy converges to 1 asz. Moreover, we prove thatE
kz
/TFWG
(z)=E
kz
/TFW
(z)+Dz
2+o(z
2) (z) and determineD. Here,E
kz
/TFW
(z) is the unmodified TFW energy.
Zusammenfassung Einem Vorschlag J. Goodismans folgend, ersetzen wir in dem Thomas-Fermi-von Weizsäcker Energiefunktional für Atome den Term durch .f z3 [0,1] ist hierbei eine Funktion, die von der Kernladungszahlz abhängt.Wir geben dann Bedingungen für die Funktionenf z an, unter denen der Quotient der so modifizierten TFW-energieE kz /TFWG (z) (kz=Anzahl der Elektronen) und der exakten quantenmechanischen Energie fürz gegen 1 konvergiert. Darüber hinaus beweisen wir, daßE kz /TFWG (z)=E kz /TFW (z)+D·o(itz) 2 (z) gilt und bestimmmenD. E kz /TFW (z) ist hierbei die nicht-modifizierte TFW-Energie.相似文献
72.
Bernhard Von Stengel 《Annals of Operations Research》1988,16(1):161-183
This paper integrates and extends the theory of the decomposition of multiattribute expected-utility functions based on utility independence. In a preliminary section, the standard decision model of expected utility is briefly discussed, including the fact that the decision maker's preference forlotteries with two outcomes determines the utility function uniquely. The decomposition possibilities of a utility function are captured by the concept ofautonomous sets of attributes, an affine separability of some kind known as generalized utility independence.Overlapping autonomous sets lead to biaffine-associative, i.e.multiplicative oradditive decompositions. The multiplicative representation shows that autonomy has strongerclosure properties than utility independence, for instance with respect to set-theoretic difference. Autonomy is also a concept with a wider scope since it applies to the decomposition of Boolean functions, games and a number of other topics in combinatorial optimization. This relationship to the well-known theory ofsubstitution decomposition in discrete mathematics also reveals a kind of discrete core behind the decomposition of utility functions. The entirety of autonomous sets can be represented by a compact data structure, the so-calledcomposition tree, which frequently corresponds to a natural hierarchy of attributes. Multiplicative/additive ormulti-affine functions correspond to the hierarchy steps. The known representation of multi-affine functions is shown to be given by aMoebius inversion formula. The entire approach has the advantage that it allows the application of more sophisticated representation methods on a detailed level, whereas it employs onlyfinite set theory andarithmetic on the main levels in the hierarchy. 相似文献
73.
74.
Dirk Lützenkirchen‐Hecht Kay Rohrmann Thomas Stöcker Wolfgang Thiel 《Surface and interface analysis : SIA》2007,39(11):845-851
Different ink‐jet printed paper materials were investigated using X‐ray photoelectron spectroscopy (XPS) yielding the elemental composition of the near‐surface region of the papers. We found significant differences with respect to the detected elements and their atomic concentrations in the different inks studied here. Two different groups of inks could be identified by means of a lower ratio of the O and C atomic concentrations and lower concentrations in specific trace elements like Mg, Na and Si. High‐resolution spectra of C 1s and O 1s core levels allowed a detailed determination of the chemical state of the respective elements. On the basis of a detailed deconvolution of these XPS signals, significant differences between all the investigated ink‐jet printed papers were found, thereby allowing their discrimination. The applicability of the measurements and, more generally, the XPS technique for forensic investigations of paper are discussed. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
75.
Naumann W 《The Journal of chemical physics》2005,123(6):64505
Fluorescence quenching by excimer formation is studied on the assumption that the excimer formation and dissociation can be modeled as overdamped motion in an attractive potential (classical potential models). An approach to the zeroth-order, concentration-independent quenching constants is proposed which starts from a mean reaction-time ansatz and reduces the calculation essentially to the solution of the eigenvalue problem for the Smoluchowski operator which describes the excimer equilibration. For a square-well potential model it is shown that a quenching constant expansion in terms of relaxation modes, truncated at the kinetic level, gives a satisfactory approximation of the recently obtained exact zeroth-order result under defined conditions. It is demonstrated how this two-mode approach can be applied for a quenching constant estimation if the excimer formation and dissociation are modeled by more realistic interaction potentials, as for instance, Morse- or Gaussian-type ones. 相似文献
76.
Wolfgang Werner 《Fresenius' Journal of Analytical Chemistry》1992,342(10):783-786
Summary Systematic quality assurance, e.g. in accordance with the provisions of ISO 9000, requires not only the targeted use of quality as a management tool, but also a revised attitude to operational procedures. Although sophisticated checking of the final results of a procedure (e.g. results of analyses, sales products, reports) meets the legal requirements and often also the customers' requirements, this misses the chance of being able to influence the quality of a final result at the earliest possible stage. It is then only possible subsequently to take the uneconomic decision as to whether the result of the work is useable or must be discarded or the object reworked. Within quality assurance, all operations are to be considered as processes with the aim of arriving at a statistically controlled process. The advantages of statistical process control are explained by way of examples from analytical procedures and production. The status of internal audits is explained as it interrelates with process control. 相似文献
77.
Kurt V. Schenker Wolfgang Von Philipsborn C. Anderson Evans Werner Skuballa Georg-Alexander Hoyer 《Helvetica chimica acta》1986,69(7):1718-1727
The configurations of the 5,6-double bond in the carbacyclins iloprost ( 3 ; (E)) and isoiloprost ( 4 ; (Z)) are based on a complete assignment of the 13C and 1H resonances determined by 1D and 2D 13C-NMR and 1H-NMR methods. 相似文献
78.
79.
7-Deoxy-N-acetylneuraminic Acid and 7-O-methyl-N-acetylneuraminic acid were synthesized through the sialic acid aldolase-catalyzed aldol addition reactions of 4-deoxy-N-acetyl-D-mannosamine and 4-O-methyl-N-acetyl-D-mannosamine, respectively, with pyruvate. The obtained sialic acids will be used as probes for the investigation of the unusual mechanism of a novel sialidase from leech. 相似文献
80.
Wolfgang Will Gerhard Hoffmann Andreas Zober 《Fresenius' Journal of Analytical Chemistry》1992,342(9):744-745
Summary A simple method is described which allows the quantification of 1-vinyl-2-pyrrolidone (NVP) in human serum. NVP is extracted from serum with diethylether and determined with HPLC/UV-detection. 1-Cyclohexyl-2-pyrrolidone serves as an internal standard. The detection limit is 0.1 mg/l. The method has shown that NVP can enter the organisms of workers occupationally exposed to this substance. 相似文献