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21.
Antonio Jiménez-Vargas Kristopher Lee Aaron Luttman Moisés Villegas-Vallecillos 《Central European Journal of Mathematics》2013,11(7):1197-1211
Let (X, d X ) and (Y,d Y ) be pointed compact metric spaces with distinguished base points e X and e Y . The Banach algebra of all $\mathbb{K}$ -valued Lipschitz functions on X — where $\mathbb{K}$ is either?or ? — that map the base point e X to 0 is denoted by Lip0(X). The peripheral range of a function f ∈ Lip0(X) is the set Ranµ(f) = {f(x): |f(x)| = ‖f‖∞} of range values of maximum modulus. We prove that if T 1, T 2: Lip0(X) → Lip0(Y) and S 1, S 2: Lip0(X) → Lip0(X) are surjective mappings such that $Ran_\pi (T_1 (f)T_2 (g)) \cap Ran_\pi (S_1 (f)S_2 (g)) \ne \emptyset $ for all f, g ∈ Lip0(X), then there are mappings φ1φ2: Y → $\mathbb{K}$ with φ1(y)φ2(y) = 1 for all y ∈ Y and a base point-preserving Lipschitz homeomorphism ψ: Y → X such that T j (f)(y) = φ j (y)S j (f)(ψ(y)) for all f ∈ Lip0(X), y ∈ Y, and j = 1, 2. In particular, if S 1 and S 2 are identity functions, then T 1 and T 2 are weighted composition operators. 相似文献
22.
Summary The reactions of TiX4 (X=Cl or Br) with the bidentate ligands, L, (Figure 1), yield hexacoordinate complexes TiX4·L, whereas similar reactions with VOCl3 lead to reduction of vanadium and give rise to vanadium(IV) pentacoordinate complexes, VOCl2·L. All the compounds have been characterized by elemental analyses, i.r., visible and e.p.r. spectra. The occupation of the sixth coordination position in pentacoordinate complexes, VOCl4·L, by different donor solvents, has been studied by means of visible and e.p.r. spectra. 相似文献
23.
Summary Titanium(IV) hexacoordinate thiuram disulphide complexes of the type [TiX4R2NC(S)SSC(S)NR2}] (X=Cl or Br; R=Me, Et, piperidinyl or morpholinyl) have been prepared by reaction between TiX4 (X=Cl or Br) and the thiuram disulphide. Similar reactions with VOCl3 lead to reduction of vanadium(V) and give rise to the oxovanadium(IV) pentacoordinate complexes [VOCl2{R2NC(S)SSC(S)NR2}]. However, the reactions of these same thiuram disulphide ligands with [VCl2(THF)2] (THF=tetrahydrofuran) cause oxidation of vanadium and to the reduction of the disulphide to the corresponding dithiocarbamate [R2NCS2]–, resulting in new dichlorobis (dithiocarbamate)vanadium(IV) complexes [VCl2-(R2NCS2)2]. All the compounds have been characterized by elemental analyses, i.r., visible and e.p.r. spectra. Both thiuram disulphides and dithiocarbamate ligands exhibit bidentate 相似文献
24.
Barragán E Olivo HF Romero-Ortega M Sarduy S 《The Journal of organic chemistry》2005,70(10):4214-4217
[reaction: see text] Addition of the chlorotitanium enolate of N-acetyl 4-isopropyl-1,3-thiazolidine-2-thione to five-membered, N-substituted N-acyl iminium ions furnished the corresponding Mannich-type addition products with good diastereoselectivity and in good yields. The synthetic utility of the addition product 8 was demonstrated in a chemospecific anti-aldol reaction with cinnamaldehyde. By using this strategy, we constructed three contiguous chiral centers with high stereocontrol employing the same chiral auxiliary. X-Ray crystallographic analysis of addition product 2 and aldol product 14 revealed their absolute stereochemistry. 相似文献
25.
For the first time symmetrized Clebsch-Gordan coefficients for corepresentations, the so called 2D- and 3D-symbols (analogous to the Wigner 2j- and 3j-symbols correspondingly) are calculated, and tabulated for all single- and double-valued corepresentations of all 90 antiunitary magnetic point groups. 相似文献
26.
Moisés Morán 《Transition Metal Chemistry》1981,6(3):173-175
Summary -Cp2Cr reacts with PX3 (X = Cl, Br or I) to give monocyclopentadienylchromium(III) derivatives -CpCrX2 (X = Cl, Br or I), while oxidative additions of IBr and ICl to -Cp2Cr give the corresponding mixed halogenated derivatives, -Cp2CrIX (X = Cl or Br). All products have been characterized by elemental analyses, magnetic moment measurements and by i.r. and e.p.r. spectra. 相似文献
27.
Wendy Flores-Fuentes Oleg Sergiyenko Félix F. Gonzalez-Navarro Moisés Rivas-López Daniel Hernandez-Balbuena Julio C. Rodríguez-Quiñonez Vera Tyrsa Lars Lindner 《Optical Review》2016,23(6):891-896
3D measurement by a cyber-physical system based on optoelectronic scanning instrumentation has been enhanced by outliers and regression data mining feedback. The prototype has applications in (1) industrial manufacturing systems that include: robotic machinery, embedded vision, and motion control, (2) health care systems for measurement scanning, and (3) infrastructure by providing structural health monitoring. This paper presents new research performed in data processing of a 3D measurement vision sensing database. Outliers from multivariate data have been detected and removal to improve artificial intelligence regression algorithm results. Physical measurement error regression data has been used for 3D measurements error correction. Concluding, that the joint of physical phenomena, measurement and computation is an effectiveness action for feedback loops in the control of industrial, medical and civil tasks. 相似文献
28.
29.
Nonsymmetrical 3,4‐Dithienylmaleimides by Cross‐Coupling Reactions with Indium Organometallics: Synthesis and Photochemical Studies 下载免费PDF全文
Dr. Ángeles Mosquera Dr. M. Isabel Férnandez Prof. Dr. Moisés Canle Lopez Prof. Dr. José Pérez Sestelo Prof. Dr. Luis A. Sarandeses 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14524-14530
The synthesis and photochemical study of novel nonsymmetrical 1,2‐dithienylethenes (DTEs) with a maleimide bridge have been carried out. The synthetic approach to the DTEs was based on successive selective palladium‐catalyzed cross‐coupling reactions of 5‐susbtituted‐2‐methyl‐3‐thiophenyl indium reagents with 3,4‐dichloromaleimides. The required organoindium reagents were prepared from 2‐methyl‐3,5‐dibromothiophene by a selective (C‐5) coupling reaction with triorganoindium compounds (R3In) and subsequent metal–halogen exchange. The coupling reactions usually gave good yields and have a high atom economy with substoichiometric amounts of R3In. The results of photochemical studies show that these novel dithienylmaleimides undergo a photocyclization reaction upon irradiation in the UV region and a photocycloreversion after excitation in the visible region, thus they can be used as photochemical switches. ON–OFF operations can be repeated in successive cycles without appreciable loss of effectiveness in the process. 相似文献
30.
Moisés Canle López M Isabel Fernández Santiago Rodríguez J Arturo Santaballa Steen Steenken Emmanuelle Vulliet 《Chemphyschem》2005,6(10):2064-2074
Phenylurea herbicides undergo low-yield (phi(PI) <15 %) monophotonic photoionisation upon 193-nm laser flash excitation. The so-formed radical cations (phenylurea.+) are highly acidic (-1.5 < pKa <0.5) and deprotonate readily to yield the corresponding neutral radical (phenylurea.). Pulse radiolysis experiments allowed limitation of the reduction potential of phenylurea.+ within 2.22 V versus the normal hydrogen electrode (NHE) < E degrees (phenylurea.+/phenylurea) < 2.43 V versus NHE. The main photoproducts of UVC (lambda=193 nm) photodegradation of phenylureas correspond to a photo-Fries rearrangement. One-electron reduction with e-(aq) yields the corresponding radical anions (phenylurea.-), for which 4.3< pKa < 5.33. The rate constants for reaction with e-(aq) show that in photocatalysis the generation of phenylurea.- and O2.- on the surface of the photocatalyst may be competitive. High reactivity toward e-(aq) is predicted from linear free-energy relationships (LFER) for phenylureas bearing electron-withdrawing groups. Reaction with HO. takes place mainly via addition to the aromatic ring and/or H. abstraction from a saturated carbon atom (98 %), rather than one-electron oxidation (2 %). High reactivity toward oxidation by HO. is predicted from LFER for phenylureas bearing electron-donating groups. Adsorption studies for TiO2 in its polymorphic forms of rutile and anatase, as well as with the commercial mixture Degussa P-25, show photocatalysis is independent of the specific area of the catalyst. A variety of compounds are generated during the photocatalytic degradation of Diuron, while only two hydroxychloro derivatives are observed upon prolonged direct 365 nm irradiation. The photocatalytic degradation proceeds mainly by oxidation of the Me group of the side chain, hydroxylation of the aromatic ring, and dechlorination. The photoproducts of photocatalytic degradation differ from one polymorphic form of TiO2 to another. 相似文献