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1.
Charles J. Colbourn Sosina S. Martirosyan Gary L. Mullen Dennis Shasha George B. Sherwood Joseph L. Yucas 《组合设计杂志》2006,14(2):124-138
A covering array CA(N;t,k, v is an N × k array such that every N × t subarray contains all t‐tuples from v symbols at least once, where t is the strength of the array. Covering arrays are used to generate software test suites to cover all t‐sets of component interactions. The particular case when t = 2 (pairwise coverage) has been extensively studied, both to develop combinatorial constructions and to provide effective algorithmic search techniques. In this paper, a simple “cut‐and‐paste” construction is extended to covering arrays in which different columns (factors) admit different numbers of symbols (values); in the process an improved recursive construction for covering arrays with t = 2 is derived. © 2005 Wiley Periodicals, Inc. J Combin Designs 14: 124–138, 2006 相似文献
2.
The injection of positrons into crystalline adamantane results in the formation of positronium (Ps). At temperatures T> 400 K the mean lifetime of the long-lived ortho-positronium exhibits a sigmoidal increase with temperature characteristic of the trapping of this species in thermally created defects. The variation is well described by the trapping model usually applied to the trapping of positrons in defects in metals. The formation energy of the defects which trap ortho-Ps is estimated at Efv = 70 ± 10 kJ mol-1 (0.73 ± 0.1 eV). This value is in good agreement with estimates of the formation energy of lattice vacancies in adamantane derived from self-diffusion studies. 相似文献
3.
The new Antiproton Accumulator Complex is now in operation at CERN. We consider the possibility of using this facility to
create and store antideuterons and conclude that we could achieve an accumulation rate of about 2·106 particles/day. No major rebuild of the rings is envisaged, but it is thought that modification to existing components and
becoming operational would take about 5 to 6 months. We stress, however, that the operation of such a facility and the use
of any stack of antideuterons for particle physics would be extremely taxing. 相似文献
4.
The valence band and core-level X-ray photoelectron spectroscopy (XPS) of iron and its oxides are reported, and the valence band spectra interpreted by various calculation models. The paper focuses upon the valence band region, which shows significant differences between the metal and the following oxidized iron species: FeO, Fe(3)O(4), alpha-Fe(2)O(3), gamma-Fe(2)O(3), alpha-FeOOH and gamma-FeOOH. The core region is of little analytical value as a means of distinguishing between these species, but the valence band region shows significant differences. These differences are consistent with spectra predicted by cluster and band structure calculations. Cluster calculations are valuable as a means for interpreting the spectra of iron oxides with multiple iron sites and defect characteristics. 相似文献
5.
Hydrazinoethyl phosphoric monoester has been prepared by reacting hydrazinoethanol with polyphosphoric acid, and isolated as di-sodium salt. Sodium hydrazinoethyl phosphate reacts with phenylisothiocyanate (in H2O+ethanol) to yield mainly the derivative thiocarbamoylated at the substituted nitrogen atom. This derivative, heated for one night at 100° in 0.5 N HCl, is cyclized to 3-amino-2-phenylimino-thiazolidine in 62% yield. Sodium hydrazinoethyl phosphate reacts with o-methoxycarbonylphenyl isothiocyanate (in H2O+dioxane) at the unsubstituted nitrogen atom to yield mainly the corresponding quinazoline derivative (IV, X = OPO3Na2). This derivative, heated for one night at 100° in 0.5 N HCl, is cyclized to 2-o-carboxyphenylamino-dihydro-δ2-1, 3, 4-thiadiazine (Va) in 55% yield (hydrolysis of the lactamic function as well). Aminoethyl phosphorous monoester (colaminephosphorous acid) reacted with phenylisocyanate (in H20+dioxane) in slightly alkaline medium (one equivalent of NaOH) yields sodium N-phenylcarbamoylaminoethyl phosphite. Refluxed for 20 minutes in 1N NaOH, this carbamoyl derivative is not cyclized but only hydrolyzed to the open-chained N-phenyl-N′-hydroxyethylurea (VII). 相似文献
6.
Thermomagnetic experiments are shown to be a useful and rapid technique for studying phase changes involving magnetic materials. Particular examples are chosen from Chromindur II (Fe28Cr10.5Co) alloys having different thermal histories. The Curie temperature of the single phase alloy is found to be ~650°C and the metastable spinodal decomposition boundary is at essentially the same temperature. The Cr-rich near equilibrium decomposition product is less magnetic and has a lower Tc, while the Cr-deficient product is more magnetic, with a Tc ? 720°C.Comparisons are made at different heating and cooling rates between temperatures measured using magnetic standards and those measured by a thermocouple in close proximity to the sample. 相似文献
7.
M. Robbins P. Gibart D.W. Johnson R.C. Sherwood V.G. Lambrecht 《Journal of solid state chemistry》1974,9(2):170-172
Phase relationships between spinel and defect NiAs structures in the systems M1?xNixCr2S4 (where M = Mn, Fe, Co) were investigated. It was found that the spinel structure is stable between x = 0 and x = 0.3 when M = Mn or Fe. When M = Co the spinel is formed in the region x = 0 to x ~ 0.4. The apparent stabilization of the defect NiAs phase by Ni2+ may be related to the strong sixfold site preference of Ni2+. Curie temperatures of all three ferrimagnetic systems increases with increasing Ni2+ substitution. This is probably due to higher NiS covalency. 相似文献
8.
[formula: see text] Hexamethylbipyrazine-N,N',N",N"'-tetraoxide (1) is synthesized in racemic form and cocrystallized with tetracyanoethylene to give a donor-acceptor (DA) networked lattice. The resulting DA2 cocrystal contains homochiral 2-D DA arrays (layers) cohered by 2.7 A NO...C=C DA bonds with periplanar O p-orbital/C=C orientations. Layer formation is stereoselective, while interlayer relations yield a racemic lattice. 相似文献
9.
Howard Sherwood 《Aequationes Mathematicae》1984,27(1):255-273
Dominates is a relation which can be defined on any collection of operations which (1) are defined on the same partially ordered set and (2) have the same identity. In this paper the family considered is a family {T p } p=?∞ ∞ of triangular norms given, for any real numberp ≠ 0, by $$T_p (a,b) = \left[ {Max(a^p + b^p - 1,0} \right]^{{1 \mathord{\left/ {\vphantom {1 p}} \right. \kern-\nulldelimiterspace} p}} $$ and, forp=?∞, 0 or ∞, by taking appropriate limits of those already defined. We sayT q dominatesT p provided $$T_q (T_p (a,b),T_p (c,d)) \geqq T_p (T_q (a,c),T_q (b,d))$$ for alla,b,c,d in [0, 1]. The main result of this paper is that dominates is transitive on this family, in fact,T q dominatesT p if and only ifq ≦p. 相似文献
10.
A copperized cadmium flow-through electrode is applied for cathodic detection of nitrate in the effluent stream of a liquid chromatograph. The nitrate is separated from dissolved oxygen in a small (10 cm) column of strong-base, anion-exchange resin (Dowex 1-X8) with 5 mM perchloric acid as the eluent. The effluent stream is buffered to pH 8 by mixing with a stream of buffer prior to detection. A large excess of chloride added to the sample dramatically improves the separation of nitrate from dissolved oxygen in the sample. 相似文献