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71.
Dussault PH Lee IQ Lee HJ Lee RJ Niu QJ Schultz JA Zope UR 《The Journal of organic chemistry》2000,65(25):8407-8414
The Lewis acid-mediated reaction of alkene nucleophiles with peroxyacetals provides an effective route for the synthesis of homologated peroxides and hydroperoxides. In the presence of Lewis acids such as TiCl(4), SnCl(4), and trimethylsilyl triflate, peroxyacetals and peroxyketals undergo reaction with allyltrimethylsilane, silyl enol ethers, and silyl ketene acetals to afford homoallyl peroxides, 3-peroxyketones, and 3-peroxyalkanoates, respectively. Reactions of peroxyacetals are Lewis acid dependent; TiCl(4) promotes formation of ethers while SnCl(4) and trimethylsilyl triflate promote formation of peroxides. Lewis acid-promoted reactions of silylated hydroperoxyacetals furnish silylated hydroperoxides, which can be deprotected to homologated hydroperoxides. Hydroperoxyketals undergo Lewis acid-mediated allylation to furnish 1,2-dioxolanes via attack of hydroperoxide on the intermediate carbocation. Lewis acid-mediated cyclization of unsaturated peroxyacetals furnishes 1,2-dioxanes, 1,2-dioxepanes, and 1,2-dioxacanes through 6-endo/exo, 7-endo/endo, and 8-endo/endo pathways. The corresponding reactions involving 6-endo/endo and 5-endo/exo pathways were unsuccessful. 相似文献
72.
Laura E. Hagopian James A. Golen Arnold L. Rheingold 《Journal of organometallic chemistry》2006,691(23):4890-4900
The electrochemistry of 1,1′-bis(dicyclohexylylphosphino)ferrocene (dcpf) was examined in methylene chloride with tetrabutylammonium hexafluorophosphate or tetrabutylammonium tetrakis(pentafluorophenyl)borate as the supporting electrolyte. The oxidation of dcpf is complicated by a follow-up reaction. Seven new complexes containing dcpf and one new compound containing 1,1′-bis(di-tert-butylphosphino)ferrocene (dtbpf) were prepared and characterized. The new complexes were analyzed by cyclic voltammetry and the oxidation of these complexes occurred at a more positive potential than the free ligand. In addition, the X-ray structure of [PdCl2(dcpf)] was determined and compared to other palladium complexes containing bisphosphinometallocene ligands. Five different palladium complexes containing bisphosphinometallocene ligands were examined as catalyst precursors in Buchwald-Hartwig catalysis. 相似文献
73.
Duyen N. K. Pham Mrittika Roy Ava Kreider-Mueller James A. Golen David R. Manke 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(5):568-574
Seven crystal structures of five first‐row (Fe, Co, Ni, Cu, and Zn) and one second‐row (Cd) transition metal–4‐picoline (pic)–sulfate complexes of the form [M(pic)x]SO4 are reported. These complexes are catena‐poly[[tetrakis(4‐methylpyridine‐κN)metal(II)]‐μ‐sulfato‐κ2O:O′], [M(SO4)(C6H7N)4]n, where the metal/M is iron, cobalt, nickel, and cadmium, di‐μ‐sulfato‐κ4O:O‐bis[tris(4‐methylpyridine‐κN)copper(II)], [Cu2(SO4)2(C6H7N)6], catena‐poly[[bis(4‐methylpyridine‐κN)zinc(II)]‐μ‐sulfato‐κ2O:O′], [Zn(SO4)(C6H7N)2]n, and catena‐poly[[tris(4‐methylpyridine‐κN)zinc(II)]‐μ‐sulfato‐κ2O:O′], [Zn(SO4)(C6H7N)3]n. The Fe, Co, Ni, and Cd compounds are isomorphous, displaying polymeric crystal structures with infinite chains of MII ions adopting an octahedral N4O2 coordination environment that involves four picoline ligands and two bridging sulfate anions. The Cu compound features a dimeric crystal structure, with the CuII ions possessing square‐pyramidal N3O2 coordination environments that contain three picoline ligands and two bridging sulfate anions. Zinc crystallizes in two forms, one exhibiting a polymeric crystal structure with infinite chains of ZnII ions adopting a tetrahedral N2O2 coordination containing two picoline ligands and two bridging sulfate anions, and the other exhibiting a polymeric crystal structure with infinite chains of ZnII ions adopting a trigonal bipyramidal N3O2 coordination containing three picoline ligands and two bridging sulfate anions. The structures are compared with the analogous pyridine complexes, and the observed coordination environments are examined in relation to crystal field theory. 相似文献
74.
Mehrdad Pourayoubi James A. Golen Arnold L. Rheingold 《Journal of Coordination Chemistry》2017,70(7):1285-1302
The first X-ray crystal structures of coordination compounds of OP[NC4H8O]3 phosphoric triamide (L) are investigated in Cl2(CH3)2Sn(trans-L)2 (1) and [Mn(H2O)4(trans-L)2]Cl2·2H2O (2) as models of molecular and salt complexes for Hirshfeld surface (HS)-based analysis. The crystal packing of 1 includes weak interactions, while in the salt complex 2, a 2-D aggregate, along the (001) plane, is mediated by normal O–H?Cl and O–H?O hydrogen bonds. In the Hirshfeld study, the crystal cohesions of 1 and 2 are recognized via H?H, O?H/H?O, and Cl?H/H?Cl contacts. Among these interactions, hydrogen bonds O–H?Cl occur in the salt structure of 2, as well as some weaker hydrogen interactions as C–H?O (1 and 2), C–H?Cl (1), and O–H?O (2). The full fingerprint plots have nearly symmetric shapes for two independent molecules of 1, while an asymmetric shape appears for the cationic component of 2. To extract more detailed information on close intermolecular contacts, the molecular surface of the previously reported structure L was also mapped. The structure 2 is the first monomeric octahedral Mn(II)–phosphoric triamide complex reported so far. Furthermore, the HS analysis of 2 is the first such study on a cation–anion complex structure including phosphoric triamide ligand. 相似文献
75.
76.
Prakash S. Nayak Jerry P. Jasinski James A. Golen Badiadka Narayana Manpreet Kaur Hemmige S. Yathirajan Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(9):889-894
The structures of four halogenated N,2‐diarylacetamides are reported and compared with a range of analogues. N‐(4‐Chloro‐3‐methylphenyl)‐2‐phenylacetamide, C15H14ClNO, (I), and N‐(4‐bromo‐3‐methylphenyl)‐2‐phenylacetamide, C15H14BrNO, (II), are isostructural in the space group P. The molecules of (I) and (II) are linked into chains of rings by a combination of N—H...O and C—H...π(arene) hydrogen bonds. The molecules of N‐(4‐chloro‐3‐methylphenyl)‐2‐(2,4‐dichlorophenyl)acetamide, C15H12Cl3NO, (III), and N‐(4‐bromo‐3‐methylphenyl)‐2‐(2‐chlorophenyl)acetamide, C15H13BrClNO, (IV), are linked into simple C(4) chains by N—H...O hydrogen bonds, but significant C—H...π(arene) interactions are absent. The N‐aryl groups in compounds (III) and (IV) adopt a different orientation, by ca 180°, from that of the corresponding groups in compounds (I) and (II), but otherwise the conformations of (I)–(IV) are very similar. Comparisons are drawn between compounds (I) and (IV) and a range of analogues of the type R1CH2CONHR2, where R2 represents a halogenated aryl ring and R1 represents either another halogenated aryl ring or a naphthalen‐1‐yl unit. 相似文献
77.
Background
It is well known that both semantic and syntactic information play a role in pronoun resolution in sentences. However, it is unclear what the relative contribution of these sources of information is for the establishment of a coreferential relationship between the pronoun and the antecedent in combination with a local structural case constraint on the pronoun (i.e. case assignment of a pronoun under preposition governing). In a prepositional phrase in German and Dutch, it is the preposition that assigns case to the pronoun. Furthermore, in these languages different overtly case-marked pronouns are used to refer to male and female persons. Thus, one can manipulate biological/syntactic gender features separately from case marking features. 相似文献78.
79.
Prof. Dr. Tarlok S. Lobana Poonam Kumari Ray J. Butcher Jerry P. Jasinski James A. Golen 《无机化学与普通化学杂志》2012,638(11):1861-1867
Reactions of copper(II) acetate with N1‐subsitituted salicylaldehyde thiosemicarbazones [R1R2C2=N3–N2H–C1(=S)–N1HR3;R1 = 2‐HO–C6H4–, R2 = H : R3 = Me (H2L1), Et (H2L2)] are described. Copper(II) acetate was reacted with H2L1 and H2L2 ligands in the presence of polypyridyl co‐ligands, and this led to the formation ofmononuclear complexes, [Cu(κ3‐O, N, S‐L1)(κ2‐N, N‐bipy)] ( 1 ),[Cu(κ3‐O, N, S‐L)(κ2‐N, N‐phen)] [L = L1 ( 3 ), L2 ( 4 )], [Cu(κ3‐O, N, S‐L)(κ2‐N, N‐tmphen)] [L =L1 ( 5 ), L2 ( 6 )] and a dinuclear complex, [Cu2L22(bipy)] ( 2 ) (bipy = 2, 2′‐bipyridine, phen = 1, 10‐phenanthroline, tmphen = 3, 4, 7, 8‐tetramethyl‐1, 10‐phenanthroline). In dinuclear complex 2 , one ligand is O, N3,S‐chelating, while second is O, N3,S‐chelation‐cum‐N2‐bridging; and in all others thio‐ligands are O, N3,S‐chelating. The μeff values for the complexes lie in the range of 1.79–1.83 BM. Complexes 1 , 3 – 6 have square pyramidal arrangement, whereas complex 2 has two independent molecules in the crystal lattice, and each molecule has trigonal bipyramidal square planar (5:4) coordination pair. Complexes 2 , 4 , and 6 showed fluorescence properties. 相似文献
80.
ICP-AES法测定色漆可溶性金属含量 总被引:1,自引:0,他引:1
用ICP-AES法测定了色漆中的“可溶性”金属铬、镉、铅元素,考察了不同酸度对分析结果的影响,优化了测试条件。进行了回收率和精密度试验。并用原子吸收光谱国标方法进行对照,结果一致。 相似文献