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101.
102.
The lithium complexes RP(3,5-tBu2C6H2OLi)2(THF)4, where R = Ph or i Pr, (R[OPO]Li2)2(THF)4, synthesized by reaction of the 2-bromo-4,6-di-tert-butylphenol with BuLi and the appropriate dichlorophosphine, possess solid state structures composed of lithium oxide tetragons arranged in a step-form or face sharing half-cubane arrangements. Incorporation of excess lithium aryloxide results in the formation of complexes that display an extended step-form structure, [Ph[OPO]Li2(ArOLi)]2, or a distorted cubane arrangement of tetragons, [iPr[OPO]Li3Cl(ArOLi)](THF)3. 相似文献
103.
Arnold PL Edworthy IS Carmichael CD Blake AJ Wilson C 《Dalton transactions (Cambridge, England : 2003)》2008,(28):3739-3746
Magnesium dications bind strongly to a tridentate anionic dicarbene ligand L = [N{CH(2)CH(2)(CNCHCHNMes)}(2)] forming dinuclear and trinuclear Mg complexes with some particularly short Mg-C bonds. Treatment of the proligand H(4)LCl(3) with three equivalents of methyl magnesium chloride or benzyl magnesium chloride affords Mg(3)(HL)Cl(6) in high yield. A suspension of in thf was heated to 80 degrees C for 2 h to afford Mg(2)(L)Cl(3), consistent with the loss of one equivalent of MgCl(2), and the deprotonation of the remaining acidic NH, lost as HCl gas. Treatment of Mg(3)(HL)Cl(6) with one equivalent of KC(8) results in deprotonation of the ligand amine NH to afford Mg(3)(L)Cl(5); treatment with a second equivalent forms the radical anion of the complex, K[Mg(3)(L)Cl(5)], which decomposes upon storage, precluding its structural characterisation. The acidic NH proton of the ligand in Mg(3)(HL)Cl(6) can also be removed by deprotonation with Li{N(SiMe(3))(2)}; additional equivalents of which also exchange the magnesium-bound chlorides for silylamido ligands, affording Mg(2)(L)Cl(2)N' and Mg(2)(L)Cl(N')(2), which have both been characterised by single-crystal X-ray diffraction studies. 相似文献
104.
Stamatatos TC Christou AG Mukherjee S Poole KM Lampropoulos C Abboud KA O'Brien TA Christou G 《Inorganic chemistry》2008,47(19):9021-9034
Convenient, high-yield routes have been developed to [Fe 10(OMe) 20(O 2CR) 10] ( 1) "ferric wheels" involving the alcoholysis of [Fe 3O(O 2CR) 6(H 2O) 3] (+) salts in MeOH in the presence of NEt 3. Reactivity studies have established [Fe 10(OMe) 20(O 2CMe) 10] ( 1a) to undergo clean carboxylate substitution with a variety of other RCO 2H groups to the corresponding [Fe 10(OMe) 20(O 2CR) 10] product. In contrast, the reaction with phenol causes a nuclearity change to give a smaller [Fe 8(OH) 4(OPh) 8(O 2CR) 12] ( 2) wheel. Similarly, reactions of [Fe 10(OMe) 20(O 2CR) 10] with the bidentate chelate ethylenediamine (en) cause a structural change to give either [Fe 8O 5(O 2CMe) 8(en) 8](ClO 4) 6 ( 3) or [Fe 2O(O 2CBu (t))(en) 4](NO 3) 3 ( 4), depending on conditions. Complex 3 possesses a "Christmas-star" Fe 8 topology comprising a central planar [Fe 4(mu 4-O)] (10+) square subunit edge-fused to four oxide-centered [Fe 3(mu 3-O)] (7+) triangular units. Variable-temperature, solid-state dc and ac magnetization studies on complexes 1a- 4 in the 5.0-300 K range established that all the complexes possess an S = 0 ground state. The magnetic susceptibility data for 4 were fit to the theoretical chi M versus T expression derived by the use of an isotropic Heisenberg spin Hamiltonian and the Van Vleck equation, and this revealed an antiferromagnetic exchange parameter with a value of J = -107.7(5) cm (-1). This value is consistent with that predicted by a previously published magnetostructural relationship. Theoretically computed values of the exchange constants in 3 were obtained with the ZILSH method, and the pattern of spin frustration within its core and the origin of its S = 0 ground state have been analyzed in detail. 相似文献
105.
106.
Carmichael D Goldet G Klankermayer J Ricard L Seeboth N Stankevic M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(19):5492-5502
Enantiopure Cp*-substituted 3,4-dimethyl-5-phenylphosphametallocene-2-methanols (M=Fe, Ru) have been prepared from the corresponding 2-carboxy-(-)-menthylphospholide anion and elaborated into 2-CH(2)PPh(2) phosphametallocenes (13: M=Fe; 14: M=Ru) and 2-CH(2)PtBuR substituted phospharuthenocenes (R=tBu, Me). The crystal structures of complexes [Rh(1,5-cod)(eta(2)-L)](+)BF(4)(-) (L=13, 14) reveal significantly different aryl group configurations. Comparative studies of the hydrogenation of para-substituted N-acetylcinnamate esters with these pre-catalysts show a superior performance for the phospharuthenocene derivative in terms of both rate and enantioselectivity. 相似文献
107.
Tasiopoulos AJ Milligan PL Abboud KA O'Brien TA Christou G 《Inorganic chemistry》2007,46(23):9678-9691
The syntheses of the first mixed-metal CeIVMnIV complexes are reported. [CeMn2O3(O2CMe)(NO3)4(H2O)2(bpy)2](NO3) (1; bpy=2,2'-bipyridine) was obtained from the reaction of Mn(NO3)2.xH2O and bpy with (NH4)2Ce(NO3)6 in a 1:1:2 molar ratio in 25% aqueous acetic acid. The complexes [CeMn6O9(O2CR)9(X)(H2O)2]y+ (R=Me, X=NO3-, y=0 (2); R=Me, X=MeOH, y=+1 (3); R=Et, X=NO3-, y=0 (7)) were obtained from reactions involving a [Mn(O2CR)2].4H2O/CeIV ratio of approximately 1:1.5 in concentrated aqueous carboxylic acid. A related reaction in less-concentrated aqueous acetic acid and in the presence of L (where L=2-hydroxy-6-methylpyridine (mhpH), 2-pyrrolidinone (pyroH), or pyridine (py)) gave [Ce3Mn2O6(O2CMe)6(NO3)2(L)a(H2O)b] (L=mhpH, a=4, b=0 (4); L=pyroH, a=2, b=3 (5)) and {{(pyH)3[Ce3Mn2O6(O2CMe)7.5(NO3)3].(HO2CMe)0.5.(H2O)2}2(NO3)}n (6), respectively. Solid-state magnetic susceptibility (chiM) data for compounds 1, 4, and 5 were fit to the theoretical chiMT versus T expression for a MnIV2 complex derived using the isotropic Heisenberg spin Hamiltonian (H=-2J?1? 2) and the Van Vleck equation. The obtained fit parameters were (in the format J, g) 1, -45.7(3) cm(-1), 1.95(5); 4, -0.40(10) cm(-1), 2.0(1); and 5, -0.34(10) cm(-1), 2.0(1), where J is the exchange interaction constant between the two MnIV ions. The data for compound 3 were fit by a matrix diagonalization method that gave J1=-5.8 cm(-1), J2=-0.63 cm(-1), J3 approximately 0, and g=2.0(1), where J1 and J2 are the exchange interactions for the [MnIV2O2(Omicron2CMe)] and [MnIV2O(Omicron2CMe)2] units, respectively, and J3 for a uniform next-nearest-neighbor interaction. Theoretical estimates of the exchange constants in compounds 1 and 3 obtained with the ZILSH method were in excellent and good agreement, respectively, with the values obtained from fits of the magnetization data. The difference for 3 is assigned to the presence of the Ce4+ ion, and atomic bond indices obtained from the ZILSH calculations were used to rationalize the values of the various exchange constants based on metal-ligand bond strengths. 相似文献
108.
Bose-Basu B Klepach T Bondo G Bondo PB Zhang W Carmichael I Serianni AS 《The Journal of organic chemistry》2007,72(20):7511-7522
13C-13C Spin-spin coupling constants (JCC) have been measured in a group of aldohexopyranoses and methyl aldopyranosides singly labeled with 13C at different sites to confirm and extend prior correlations between JCC magnitude and sign and saccharide structure. Structural correlations for 2JC1,C3, 2JC2,C4, 2JC4,C6, and 2JC1,C5 have been confirmed using density functional theory calculations to test empirical predictions. These geminal couplings depend highly on the orientation of C-O bonds appended to the terminal coupled carbons, but new evidence suggests that 2JCCC values are also affected by intervening carbon structure and C-O bond rotation. 3JC1,C6 and 3JC3,C6 values show Karplus-like dependences but also are affected by in-plane terminal hydroxyl substituents. In both cases, rotation about the C5-C6 bond modulates the coupling due to the alternating in-plane and out-of-plane O6. 3JC3,C6 is also affected by C4 configuration. Both 3JC1,C6 and 3JC3,C6 are subject to remote effects involving the structure at C3 and C1, respectively. New structural correlations have been determined for 2JC3,C5, which, like 3JC3,C6, shows a remote dependence on anomeric configuration. Investigations of dual pathway 13C-13C couplings, 3+3JC1,C4 and 3+3JC2,C5, revealed an important additional internal electronegative substituent effect on 3JCC in saccharides, a structural factor undocumented previously and one of importance to the interpretation of trans-glycoside 3JCOCC in oligosaccharides. 相似文献
109.
Angelo J. Madonna Kent J. Voorhees Ted L. Hadfield Edward J. Hilyard 《Journal of the American Society for Mass Spectrometry》1999,10(6):502-511
Mass spectrometry coupled with a pyrolysis inlet system was used to investigate media from cell cultures infected with viruses. Cell culture media is an intricate mixture of numerous chemical constituents and cells that collectively produce complicated mass spectra. Cholesterol and free fatty acids were identified and attributed to lipid sources in the media (blood serum supplement and plasma membranes of host cells). These lipid moieties could be utilized as signature markers for rapidly detecting the cell culture media. Viruses are intracellular parasites and are dependent upon host cells in order to exist. Therefore, it is highly probable that significant quantities of media needed to grow and maintain viable host cells would be present if a viral agent were disseminated as an aerosol into the environment. Cholesterol was also detected from a purified virus sample, further substantiating its use as a target compound for detection. Implications of this research for detection of viral bioaerosols, using a field-portable pyrolysis mass spectrometer, is described. 相似文献
110.