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11.
Stephen E Huang D Shaw JL Blake AJ Collison D Davies ES Edge R Howard JA McInnes EJ Wilson C Wolowska J McMaster J Schröder M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(37):10246-10258
The NiII complexes [Ni([9]aneNS2‐CH3)2]2+ ([9]aneNS2‐CH3=N‐methyl‐1‐aza‐4,7‐dithiacyclononane), [Ni(bis[9]aneNS2‐C2H4)]2+ (bis[9]aneNS2‐C2H4=1,2‐bis‐(1‐aza‐4,7‐dithiacyclononylethane) and [Ni([9]aneS3)2]2+ ([9]aneS3=1,4,7‐trithiacyclononane) have been prepared and can be electrochemically and chemically oxidized to give the formal NiIII products, which have been characterized by X‐ray crystallography, UV/Vis and multi‐frequency EPR spectroscopy. The single‐crystal X‐ray structure of [NiIII([9]aneNS2‐CH3)2](ClO4)6?(H5O2)3 reveals an octahedral co‐ordination at the Ni centre, while the crystal structure of [NiIII(bis[9]aneNS2‐C2H4)](ClO4)6?(H3O)3? 3H2O exhibits a more distorted co‐ordination. In the homoleptic analogue, [NiIII([9]aneS3)2](ClO4)3, structurally characterized at 30 K, the Ni? S distances [2.249(6), 2.251(5) and 2.437(2) Å] are consistent with a Jahn–Teller distorted octahedral stereochemistry. [Ni([9]aneNS2‐CH3)2](PF6)2 shows a one‐electron oxidation process in MeCN (0.2 M NBu4PF6, 293 K) at E1/2=+1.10 V versus Fc+/Fc assigned to a formal NiIII/NiII couple. [Ni(bis[9]aneNS2‐C2H4)](PF6)2 exhibits a one‐electron oxidation process at E1/2=+0.98 V and a reduction process at E1/2=?1.25 V assigned to NiII/NiIII and NiII/NiI couples, respectively. The multi‐frequency X‐, L‐, S‐, K‐band EPR spectra of the 3+ cations and their 86.2 % 61Ni‐enriched analogues were simulated. Treatment of the spin Hamiltonian parameters by perturbation theory reveals that the SOMO has 50.6 %, 42.8 % and 37.2 % Ni character in [Ni([9]aneNS2‐CH3)2]3+, [Ni(bis[9]aneNS2‐C2H4)]3+ and [Ni([9]aneS3)2]3+, respectively, consistent with DFT calculations, and reflecting delocalisation of charge onto the S‐thioether centres. EPR spectra for [61Ni([9]aneS3)2]3+ are consistent with a dynamic Jahn–Teller distortion in this compound. 相似文献
12.
Gardner BM Patel D Cornish AD McMaster J Lewis W Blake AJ Liddle ST 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(40):11266-11273
Four new uranium-ruthenium complexes, [(Tren(TMS))URu(η(5)-C(5)H(5))(CO)(2)] (9), [(Tren(DMSB))URu(η(5)-C(5)H(5))(CO)(2)] (10), [(Ts(Tolyl))(THF)URu(η(5)-C(5)H(5))(CO)(2)] (11), and [(Ts(Xylyl))(THF)URu(η(5)-C(5)H(5))(CO)(2)] (12) [Tren(TMS)=N(CH(2)CH(2)NSiMe(3))(3); Tren(DMSB)=N(CH(2)CH(2)NSiMe(2)tBu)(3)]; Ts(Tolyl)=HC(SiMe(2)NC(6)H(4)-4-Me)(3); Ts(Xylyl)=HC(SiMe(2)NC(6)H(3)-3,5-Me(2))(3)], were prepared by a salt-elimination strategy. Structural, spectroscopic, and computational analyses of 9-12 shows: i) the formation of unsupported uranium-ruthenium bonds with no isocarbonyl linkages in the solid state; ii) ruthenium-carbonyl backbonding in the [Ru(η(5)-C(5)H(5))(CO)(2)](-) ions that is tempered by polarization of charge within the ruthenium fragments towards uranium; iii) closed-shell uranium-ruthenium interactions that can be classified as predominantly ionic with little covalent character. Comparison of the calculated U-Ru bond interaction energies (BIEs) of 9-12 with the BIE of [(η(5)-C(5)H(5))(3)URu(η(5)-C(5)H(5))(CO)(2)], for which an experimentally determined U-Ru bond disruption enthalpy (BDE) has been reported, suggests BDEs of approximately 150 kJ mol(-1) for 9-12. 相似文献
13.
Benisvy L Bill E Blake AJ Collison D Davies ES Garner CD McArdle G McInnes EJ McMaster J Ross SH Wilson C 《Dalton transactions (Cambridge, England : 2003)》2006,(1):258-267
Two pro-ligands ((R)LH) comprised of an o,p-di-tert-butyl-substituted phenol covalently bonded to a benzimidazole ((Bz)LH) or a 4,5-di-p-methoxyphenyl substituted imidazole ((PhOMe)LH), have been structurally characterised. Each possesses an intramolecular O-H[dot dot dot]N hydrogen bond between the phenolic O-H group and an imidazole nitrogen atom and (1)H NMR studies show that this bond is retained in solution. Each (R)LH undergoes an electrochemically reversible, one-electron, oxidation to form the [(R)LH] (+) radical cation that is considered to be stabilised by an intramolecular O...H-N hydrogen bond. The (R)LH pro-ligands react with M(BF(4))(2).H(2)O (M = Cu or Zn) in the presence of Et(3)N to form the corresponding [M((R)L)(2)] compound. [Cu((Bz)L)(2)] (), [Cu((PhOMe)L)(2)] (), [Zn((Bz)L)(2)] and [Zn((PhOMe)L)(2)] have been isolated and the structures of .4MeCN, .2MeOH, .2MeCN and .2MeCN determined by X-ray crystallography. In each compound the metal possesses an N(2)O(2)-coordination sphere: in .4MeCN and .2MeOH the {CuN(2)O(2)} centre has a distorted square planar geometry; in .2MeCN and .2MeCN the {ZnN(2)O(2)} centre has a distorted tetrahedral geometry. The X-band EPR spectra of both and , in CH(2)Cl(2)-DMF (9 : 1) solution at 77 K, are consistent with the presence of a Cu(ii) complex having the structure identified by X-ray crystallography. Electrochemical studies have shown that each undergo two, one-electron, oxidations; the potentials of these processes and the UV/vis and EPR properties of the products indicate that each oxidation is ligand-based. The first oxidation produces [M(II)((R)L)((R)L )](+), comprising a M(ii) centre bound to a phenoxide ((R)L) and a phenoxyl radical ((R)L ) ligand; these cations have been generated electrochemically and, for R = PhOMe, chemically by oxidation with Ag[BF(4)]. The second oxidation produces [M(II)((R)L )(2)](2+). The information obtained from these investigations shows that a suitable pro-ligand design allows a relatively inert phenoxyl radical to be generated, stabilised by either a hydrogen bond, as in [(R)LH] (+) (R = Bz or PhOMe), or by coordination to a metal, as in [M(II)((R)L)((R)L )](+) (M = Cu or Zn; R = Bz or PhOMe). Coordination to a metal is more effective than hydrogen bonding in stabilising a phenoxyl radical and Cu(ii) is slightly more effective than Zn(II) in this respect. 相似文献
14.
Given an ordered set E and a topological space X, we say that E can be realized within X if there is an injection j from E into the class of (homeomorphism classes of) subspaces of X such that, for x, y in E, x y if and only if j(x) is homeomorphically embeddable into j(y). It is known, for instance, that transfinite induction demonstrates that every partially-ordered set of cardinality c (and some larger ones) can be realized within the real line. We explore aspects of the realizability problem, indicating, in particular, how to weaken the hypothesis on E from partial- to quasi-order, and seeking to isolate the characteristics of the real line that are relevant here. 相似文献
15.
Liddle ST McMaster J Green JC Arnold PL 《Chemical communications (Cambridge, England)》2008,(15):1747-1749
The first structurally authenticated yttrium-alkyl-alkylidene is reported; structural, spectroscopic, and theoretical analyses show that whilst the yttrium-alkylidene bond is short, it possesses a bond order less than one and is comparable to the Y-C(alkyl) single bond within the same molecule. 相似文献
16.
17.
Ali Badiee Mahmoud R. Jaafari Ali Khamesipour Afshin Samiei Dina Soroush Masoumeh Tavassoti Kheiri Farzaneh Barkhordari W. Robert McMaster Fereidoun Mahboudi 《Colloids and surfaces. B, Biointerfaces》2009,74(1):37-44
Development of new generation vaccines requires adjuvants to elicit the type and intensity of immune response needed for protection. Liposomes have been shown to be an effective adjuvant formulation. In this study, the role of liposome bilayer composition with different phase transition temperature (Tc) to induce a T helper 1 (Th1) type of immune response and protection against leishmaniasis in BALB/c mice was assessed. Liposome formulations with different bilayer compositions consisting of egg phosphatidylcholine (EPC, Tc < 0 °C), dipalmitoylphosphatidylcholine (DPPC, Tc 41 °C), or distearoylphosphatidylcholine (DSPC, Tc 54 °C) were prepared. All liposomes were contained rgp63 as a recombinant antigen and used to immunize mice subcutaneously 3 times in 3-week intervals. Evaluation of lesion development and splenic parasite burden after challenge with L. major, evaluation of Th1 cytokine (IFN-γ) and Th2 cytokine (IL-4), and titration of IgG isotypes were carried out to assess the type of generated immune response and extent of protection. The results indicated the generated immune response in mice was influenced by the bilayer composition of liposomes, so that mice immunized with liposomes consisting of EPC induced a Th2 type of immune response while liposome consisting of DPPC or DSPC induced Th1 type of immune response. It seems that liposomes prepared with higher Tm phospholipids are suitable formulation to induce Th1 type of immune response and protection, and so might be used for further investigations to develop an effective vaccine against leishmaniasis. 相似文献
18.
Reductive desulfurisation of dithiocarbamates is conveniently achieved using H(3)PO(2)-Et(3)N-ACCN in refluxing dioxane. Fused and spirocyclic β-lactams, prepared through 4-exo trig carbamoyl radical cyclisation-dithiocarbamate group transfer reactions, are reduced without fragmentation of the strained 4-membered ring. Diethyl tetraacetyl-d-glucopyranosyl dithiocarbamate is selectively reduced with or without acyloxy group migration depending on reaction conditions and choice of reductant. Deuterium incorporation from D(3)PO(2)-Et(3)N is observed for a system involving a nucleophilic radical intermediate, but not in the case of the electrophilic radical obtained through acyloxy group migration on a glucose derivative. 相似文献
19.
The organometallic produced by controlled lithiation of allene functions as an efficient propargylic anion equivalent in coupling reactions with alkyl and allyl halides. 相似文献
20.
Benisvy L Blake AJ Collison D Davies ES Garner CD McInnes EJ McMaster J Whittaker G Wilson C 《Chemical communications (Cambridge, England)》2001,(18):1824-1825
A new N,O-bidentate pro-ligand (HL), [ML2] (M = Cu, Zn) and [CuL2][BF4] have been synthesised; [CuL2].4DMF and [CuL2][BF4].2CH2Cl2 have been crystallographically and spectroscopically characterised; these data indicate that [CuL2]+ cations are constituted as [Cu2+(L.)(L-)]+ and involve the phenoxyl radical L.. 相似文献