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761.
Muralidhara Thimmaiah 《Tetrahedron letters》2008,49(39):5605-5607
Using a bulky electron-rich monodentate benzoferrocenyl phosphine as supporting ligand, an efficient protocol for stereoselective palladium-catalyzed Suzuki-Miyaura cross-coupling of aryl chlorides with alkenylboronic acids was uncovered. Using this protocol, both trans- and cis-alkenylboronic acids can be coupled with high stereoselectivity giving the corresponding vinylarenes in good to quantitative yields. Electron-poor and -rich aryl chlorides including highly hindered ones are all suitable substrates for the reaction. 相似文献
762.
763.
764.
Solid complexes [REL(NO3)3]n with novel (10,3)-a type three-dimensional networks structure have been assembled using rare earth nitrates and an amide type semirigid tripodal bridging ligand, 1,3,5-tris {[(2′-benzylaminoformyl)phenoxyl]methyl}benzene (L), as building blocks. The complexes were crys- tallized in the orthorhombic system with chiral space group P212121. The whole structure consists of an infinite array of trigonal RE(III) ions bridged by tridentate ligands, and a novel (10,3)-a net is formed, which is very uncommon in the rare earth complexes. At room temperature, the Sm(III), Eu(III), Tb(III), Dy(III) complexes all exhibited characteristic luminescence emissions of central metal ions under UV light excitation. 相似文献
765.
Two new Fischer-type carbene-containing trinuclear transition-metal clusters: (μ
3-S)Co3(CO)7[μ, η
2-SCNEt2] 1 and CoRu2(CO)9[μ
3, η
2-SCNEt2] 2 were obtained by the reaction of tris(N,N-diethyldithiocarbamato)cobalt with Co2(CO)8 and Ru3(CO)12. These clusters contain thiocarboxamido ligand in different coordination modes. The thiocarboxamido ligand served as monometalated
or dimetalated sulfur(diethy1amino) carbene ligand in these clusters. Clusters 1 and 2 were characterized by IR, 1H NMR, and single-crystal X-ray diffraction. 相似文献
766.
Jean d’Angelo Georges Morgant Nour Eddine Ghermani Didier Desmaële Bernard Fraisse François Bonhomme Emma Dichi Mehrez Sghaier Yanling Li Yves Journaux John R.J. Sorenson 《Polyhedron》2008
Purposes of these studies were to synthesize Zn(II) and Co(II) complexes of 3-nitro-4-hydroxybenzoic acid, determine their structures through X-ray crystallography, and obtain their anticonvulsant activities. Thermogravimetric, differential scanning calorimetry, impedance of aqueous solutions and magnetic properties analyses were also determined. Anticonvulsant and related activities of these complexes as well as Zn(II), Co(II), Ni(II) and Mg(II) (5-nitrosalicylato) complexes were determined by the National Institutes of Health, Antiepileptic Development Program. Results of these analyses are presented to document unique bonding features and physical properties of these compounds and their anticonvulsant activities. It is concluded that these compounds have chemical and physical properties that can be used to account for their anticonvulsant activities. 相似文献
767.
Three ligands with flexible bis-terdentate coordination sites, di(2-pyridylcarbaldehyde)-6,6′-dicarboxylic acid hydrazone-2,2′-bipyridine (H2L1), di(2-acetylpyridyl)-6,6′-dicarboxylic acid hydrazone-2,2′-bipyridine (H2L2) and di(2-pyridylketone)-6,6′-dicarboxylic acid hydrazone-2,2′-bipyridine (H2L3) have been easily prepared. Dinuclear double-stranded helicates Co2(L1)2(ClO4)2(C2H5OH)2(H2O)2 (1), Co2(HL2)(L2)(ClO4)3(C2H5OH)2(H2O)2 (2) and Co2(HL3)(L3)(ClO4)3(H2O)4 (3) based on the ligands, H2L1–3, respectively, have been obtained via self-assembly, their structures were determined by FT-IR, Elemental Analysis, ESI-MS and X-ray diffraction method. 相似文献
768.
Michel M. Blomb Justin Nenwa Evamarie Hey-Hawkins Peter Lnnecke Peter Strauch Klaus R. Koch 《Polyhedron》2008,27(18):3688-3692
The new salt, tetra-n-butylammonium bis(benzene-1,2-dithiolato(2−)-κ2S,S′)platinate(III), [NBu4][Pt(C6H4S2)2] (1), has been synthesized in ethanol/water, and fully characterized by single crystal X-ray structure determination. The central platinum in the complex ion [Pt(bdt)2]− is tetracoordinated by the S atoms of the bdt2− ligands (bdt2− is benzene-1,2-dithiolate) in a square-planar geometry. The well-resolved frozen solution EPR spectrum exhibits rhombic symmetry. The room temperature effective magnetic moment (μeff = 1.80 Bohr magneton) is in line with this spectrum and strongly supports the Pt(III) oxidation state in 1. This observation is in excellent agreement with previous results reported on closely related Ni(III), Pd(III) and Pt(III) species. 相似文献
769.
Scheuermann S Kretz T Vitze H Bats JW Bolte M Lerner HW Wagner M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(8):2590-2601
The synthesis, structural characterisation and coordination behaviour of mono- and ditopic p-hydroquinone-based bis(pyrazol-1-yl)methane ligands is described (i.e., 2-(pz2CH)C6H3(OH)2 (2a), 2-(pz2CH)-6-(tBu)C6H2(OH)2 (2b), 2-(pz2CH)-6-(tBu)C6H2(OSiiPr3)(OH) (2c), 2,5-(pz2CH)2C6H2(OH)2 (4)). Ligands 2a, 2b and 4 can be oxidised to their p-benzoquinone state on a preparative scale (2a ox, 2b ox, 4 ox). An octahedral Ni II complex [trans-Ni(2c)2] and square-planar Pd II complexes [Pd2bCl2] and [Pd2b ox Cl2] have been prepared. In the two Pd II species, the ligands are coordinated only through their pyrazolyl rings. The fact that [Pd2bC12] and [Pd2b oxC12] are isolable compounds proves that redox transitions involving the p-quinone substituent are fully reversible. In [Pd2b oxCl2], the methine proton is highly acidic and can be abstracted with bases as weak as NEt(3). The resulting anion dimerises to give a dinuclear macrocyclic Pd II complex, which has been structurally characterised. The methylated ligand 2-(pz2CMe)C6H3O2 (11 ox) and its Pd II complex [Pd11 oxCl2] are base-stable. A new class of redox-active ligands is now available with the potential for applications both in catalysis and in materials science. 相似文献
770.
Himeda Y Onozawa-Komatsuzaki N Miyazawa S Sugihara H Hirose T Kasuga K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(35):11076-11081
Transfer hydrogenation catalyzed by an iridium catalyst with 4,4'-dihydroxy-2,2'-bipyridine (DHBP) in an aqueous formate solution exhibits highly pH-dependent catalytic activity and chemoselectivity. The substantial change in the activity is due to the electronic effect based on the acid-base equilibrium of the phenolic hydroxyl group of DHBP. Under basic conditions, high turnover frequency values of the DHBP complex, which can be more than 1000 times the value of the unsubstituted analogue, are obtained (up to 81 000 h(-1) at 80 degrees C). In addition, the DHBP catalyst exhibits pH-dependent chemoselectivity for alpha,beta-unsaturated carbonyl compounds. Selective reduction of the C=C bond of enone with high activity are observed under basic conditions. The ketone moieties can be reduced with satisfactory activity under acidic conditions. In particular, pH-selective chemoselectivity of the C=O versus C=C bond reduction was observed in the transfer hydrogenation of cinnamaldehyde. 相似文献