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81.
The new polyoxotungstates
H2O (1),
· 28H2O (2) and
H2O (3) were synthesized in aqueous solution and characterized by IR and Raman spectroscopy, energy dispersive X-ray fluorescence and single-crystal X-ray analysis. The anions in 1 and 2 are the first structurally characterized sandwich-type polyoxoanions which contain trivalent manganese atoms. The manganese atoms are coordinated by four oxygen atoms of two
Keggin fragments and one water molecule, forming a square pyramid. The manganese(II) containing anions in 3 are linked via Mn–O–W-bonds, forming a two-dimensional network.Dedicated to Prof. M.T. Pope on the occasion of his retirement. 相似文献
82.
Saalfrank RW Scheurer A Bernt I Heinemann FW Postnikov AV Schünemann V Trautwein AX Alam MS Rupp H Müller P 《Dalton transactions (Cambridge, England : 2003)》2006,(23):2865-2874
Star-shaped complex [Fe(III)[Fe(III)(L1)2]3] (3) was synthesized starting from N-methyldiethanolamine H2L1 (1) and ferric chloride in the presence of sodium hydride. For 3, two different high-spin iron(III) ion sites were confirmed by M?ssbauer spectroscopy at 77 K. Single-crystal X-ray structure determination revealed that 3 crystallizes with four molecules of chloroform, but, with only three molecules of dichloromethane. The unit cell of 3.4CHCl3 contains the enantiomers (delta)-[(S,S)(R,R)(R,R)] and (lambda)-[(R,R)(S,S)(S,S)], whereas in case of 3.3CH2Cl2 four independent molecules, forming pairs of the enantiomers [lambda-(R,R)(R,R)(R,R)]-3 and [lambda-(S,S)(S,S)(S,S)]-3, were observed in the unit cell. According to SQUID measurements, the antiferromagnetic intramolecular coupling of the iron(III) ions in 3 results in a S = 10/2 ground state multiplet. The anisotropy is of the easy-axis type. EPR measurements enabled an accurate determination of the ligand-field splitting parameters. The ferric star 3 is a single-molecule magnet (SMM) and shows hysteretic magnetization characteristics below a blocking temperature of about 1.2 K. However, weak intermolecular couplings, mediated in a chainlike fashion via solvent molecules, have a strong influence on the magnetic properties. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) were used to determine the structural and electronic properties of star-type tetranuclear iron(III) complex 3. The molecules were deposited onto highly ordered pyrolytic graphite (HOPG). Small, regular molecule clusters, two-dimensional monolayers as well as separated single molecules were observed. In our STS measurements we found a rather large contrast at the expected locations of the metal centers of the molecules. This direct addressing of the metal centers was confirmed by DFT calculations. 相似文献
83.
84.
Summary The reaction of 2-ary-5-hydroxy-3(2H)-pyridazinones (1a, b) with bromine yields the 4-bromo derivatives2a, b and with sulfuryl chloride the chloro compounds3a, b are obtained. However, with an excess of chlorine or sulfuryl chloride the 4,4-dichloro-pyridazine-dione4 is produced. Hydrolysis of4 leads to5, and in a similar manner the open chain hydrazone8 is obtained from the carboxylic acid6.
Pyridazine mit Heteroatom-Substituenten in Stellung 3 und 5, 7. Mitt. Halogenierung von 2-Aryl-5-hydroxy-pyridazin-3(2H)-onen in 4-Stellung
Zusammenfassung Die Reaktion von 2-Aryl-5-hydroxy-pyridazin-3(2H)-onen (1a, b) mit Brom liefert die 4-Bromderivate2a, b, während mit Sulfurylchlorid3a, b erhalten werden. Ein Überschuß von Sulfurychlorid oder Chlorgas gibt jedoch das 4,4-Dichlor-pyridazin-dion4. Die Hydrolyse von4 führt unter Ringöffnung und Decarboxylierung zu5. In analoger Weise gibt die freie Carbonsäure6 das Hydrazon8.相似文献
85.
Selenogermanates from Aqueous Solution: Preparation and Structure of Na4Ge2Se6 · 16 H2O Selenogermanates(IV) are prepared from aqueous solutions by reaction of alkali selenides with GeSe2. Na4Ge2Se6 · 16 H2O, being obtained from stoichiometric 1:1 quantities, is characterized by a complete X-ray structure analysis and by vibrational spectra. The compound is monoclinic (P21/c) with a = 9.894(4), b = 11.781(5), c = 12.225(6) Å, β = 92.90(4)°, Z = 2. It contains isolated Ge2Se64? anions consisting of two edge-sharing tetrahedra [Ge? Se 2.303(2)–2.419(2) Å] which are in contact to the hydrated octahedral [Na(H2O)6]+ ions through Se ? H? O bridges within an extensive hydrogen bridge system. Raman-active vibrations are observed at 306, 294, 207, 139, and 121 cm?1. Adamantane-like Ge4Se104? can be prepared in a similar way as Ge2Se64? if a 1:2 molar ratio of alkali selenide to GeSe2 is employed. 相似文献
86.
For the first time perthioborates with trigonal planar coordination of boron were prepared. Na2B2S5 (Pnma, a = 12.545(2) Å, b = 7.441(1) Å, c = 8.271(1) Å, Z = 4) and Li2B2S5 (Cmcm, a = 15.864(1) Å, b = 6.433(1) Å, c = 6.862(1) Å, Z = 4) were obtained by reaction of the metal sulfides with stoichiometric amounts of boron and an excess of sulfur (effective molar ratio M:B:S = 1:1:4) at 600°C (650°C) and subsequent annealing. The non-isotypic structures contain exactly planar [B2S5]2? groups consisting of five-membered B2S3 rings with one additional exocyclic sulfur on each of the boron atoms. The alkaline metal cations are four-coordinate (lithium) and (four + four)-coordinate (sodium) respectively. 相似文献
87.
Synthesis and Characterization of Novel Five‐ and Six‐coordinate Manganese Complexes as Catechol Dioxygenase Models The five‐ and six‐coordinate manganese complexes [Mn(tphhp)Cl2] {tphhp = N,N′‐bis(2‐pyridylmethyl)‐2‐(2‐pyridyl)hexahydropyrimidine} ( 1 ), [Mn(bpma)Cl](ClO4) {bpma = bis((2‐pyridylmethyl)((1‐methylbenzimidazol‐2‐yl)‐methyl)amine} ( 2 ) and [Mn(L)TCC] {HL = (1‐hydroxy‐4‐nitrobenzyl)((1‐methylimidazol‐2‐yl)methyl)(2‐pyridylmethyl)amine} ( 3 ) were synthesized and characterized by various techniques such as single crystal X‐ray structure analysis, mass spectrometry, IR and UV/vis spectroscopy, cyclic voltammetry, and elemental analysis. 1 and 2 crystallize in the monoclinic space group P21/n (No. 14) ( 1 ) and P21/c (No. 14) ( 2 ). The ligand and the chlorine ions provide the N3Cl2‐donorset in 1 and the N3Cl2‐donorset in 2 , respectively. Compounds 1 and 2 show catalytic activity regarding the oxidation of 3,5‐di‐tertbutylcatechol to 3,5‐di‐tert‐butylchinon. To our knowledge, 1 and 2 are the first five‐coordinate manganese complexes that show catecholase activity. 3 crystallize in the orthorhombic space group P212121 (No. 19) and the ligand and tetrachlorocatechol (TCC) build the N3O3‐donorset in 3 . 相似文献
88.
89.
90.