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21.
22.
J. V. Brenčič L. Golič I. Leban P. Šegedin 《Monatshefte für Chemie / Chemical Monthly》1979,110(5):1221-1228
Mo2Cl4
Pic
4·CHCl3 (A) (Pic=4-methylpyridine) and Mo2Br4
Pic
4 (B) crystallize in the monoclinic space group.A inC2/c (No. 15) witha=15.175 (4),b=10.847 (2),c=19.946 (6) and =104.52 (2)°;D
o=1.71 (2),D
c
=1.72 gcm–3 forZ=4.B inP2l/n
(No. 14) witha=9.270 (3),b=16.614 (5),c=9.305 (3) and =91.96 (5)°;D
o=2.03 (3),D
c
=2.05 gcm–3 forZ=2.Two halogens and 4-methylpyridines of the MoX
2
Pic
2 group are in the trans position. Mo–Mo bond lengths are 2.153 96) forA and 2.150 92) forB. Both molecules are situated on the inversion center resulting in the eclipsed configuration of the ligands around the molybdenum pair. The structure ofB has been refined to the conventionalR factors of 0.08 and 0.098. Disorder on the part of 4-methylpyridines and chloroform molecules stopped the refinement ofA at the endR value of 0.175.Mean Mo–X and Mo–N bonding distances are 2.40 (2), 2.25 (5) forA and 2.53 (3), 2.25 (1) forB. 相似文献
23.
Jurij Svete Branko Stanovnik Miha Tiler Ljubo Goli
Ivan Leban 《Journal of heterocyclic chemistry》1989,26(1):145-153
From heteroarylaminomethyleneoxazolones 4 , obtained from N-heteroarylformamidines 2 and 2-phenyl-5-oxo-4,5-dihydro-1,3-oxazole ( 3 ), the following β-heteroarylamino-α,β-dehydro-α-amino acid derivatives were prepared: methyl 8 and ethyl esters 9 , amides 10 and 11 , hydrazides 12 , and azides 15 . By catalytic hydrogenation the compounds 4 were converted into β-heteroarylamino substituted amides 18 and β-heteroarylamino-α-amino acids 20 . 相似文献
24.
Cis-[Cr(en)2F2]ClO4 · NaClO4 · H2O (en = 1,2-diaminoethane) was obtained as the red crystalline product from the saturated solutions of both NaClO4 and cis-[Cr(en)2F2]ClO4 in water. The compound crystallizes in the monoclinic P21/n (No.14) space group with a = 9.540(2), b = 11.840(2); c = 14.659(3) Å, β = 95.02(1)°, Z = 4. The unit cell of the racemic crystal contains cis-[Cr(en)2F2]+ in the Λλλ and Δδδ enantiometric forms, Na+, ClO4?, and lattice H2O. Cr has octahedral coordination. Cr? F and Cr? N bonds are 1.868(4), 1.887(5) and from 2.067(2) to 2.100(8) Å. Mean Cl? O bond is 1.38 Å. Na+ ions are in the distorted octahedral environment. Infrared spectrum confirms the presence of the lattice H2O and proves the cis structure of [Cr(en)2F2]+. 相似文献
25.
The title complex, μ‐octane‐1,8‐dioato‐bis[bis(3‐aminopyridine)chloro(methanol)cobalt(II)], [Co2(C8H12O4)Cl2(C5H6N2)4(CH4O)2], is located on a crystallographic centre of inversion. The coordination around each of the Co centres is distorted octahedral, involving two N, three O and one Cl atom. Discrete dimers are connected in a three‐dimensional arrangement through N—H⋯O, N—H⋯Cl and O—H⋯O hydrogen‐bond interactions. 相似文献
26.
27.
28.
Three Cu(II) halido complexes of 3-pyridinepropanol (3-pyprop), 2-pyridineethanol (2-pyet), and 2-pyridinemethanol (2-pymet)
have been prepared and investigation of their crystal structures undertaken. All the reported products contain simple pyridine
alcohols as neutral ligands. Cu(3-pyprop)2Br2, 1, exhibits square-planar coordination geometry with the axial sites involved in weak bridging contact with the neighboring
units to form infinite chains. Reaction of CuBr2 with 2-pyet leads to an ionic complex [Cu(2-pyet)2Br]Br, 2, with distorted square-pyramidal coordination environment: the Cu center in the cation is surrounded by two 2-pyet ligands,
coordinated in chelating manner, and a bromide. Reaction of CuCl2 with 2-pymet resulted in the formation of a dinuclear ionic complex Cu2(2-pymet)4Cl2]Cl2·2H2O, 3. The centrosymmetric cation consisted of two Cu ions doubly bridged by chlorides and coordinated by chelating 2-pymet ligands.
The positive charge is balanced by free chlorides involved in hydrogen bonds with the lattice water molecules. 相似文献
29.
[reaction: see text] A new synthesis of L-noviose (11), a sugar moiety of novobiocin, is presented. D-Gulonolactone was initially converted in a few steps to the key ester derivative 7 [1-O-benzyl methyl 2,3-O-(1-methylethylidene)-alpha-L-lyxofuranosiduronate]. An appropriate selection of protecting groups enabled transformation of 7 under mild reaction conditions to 4-O-demethyl-L-noviofuranose 9a and related 9b-c. Derivatives 9 were further converted either to L-lyxopyranoses (10a and 10b) or to methyl L-lyxofuranoside 12. 相似文献
30.
The crystal structure of trans-pyH[MoBr4py2] has been determined: orthorhombic, Pnma (No. 62), a = 16.197(3), b = 13.995(3), c = 8.615(1) Å, Z = 4, Dc = 2.23, Do = 2.20(3) g/cm3, V = 1 953(1) Å3. R1, Rw = 0.057 and 0.053. Trans-[MoBr4py2]? anions with staggered conformation of pyridine rings are located on the mirror planes. Mo? Br, Mo? N(pyridine) distances are 2.593(1), 2.573(1), 2.227(8) and 2.213(7) Å. Cations are located on the symmetry centers. The cation in trans-pyH[MBr4py2] can be replaced. Trans-NH4[MBr4py2] · H2O, Cs[MBr4py2], LH[MBr4py2] (M = Mo, W; L = 4-methylpyridine, 4-pic; 2,2′-bipyridyl, bipy) were prepared. The compounds of molybdenum and tungsten with the same chemical composition are isostructural. All compounds react with pyridine and 4-methylpyridine. The products are trans-MBr3L3, and in the case of molybdenum, also trans-MoBr3py2(4-pic). Bromine oxidizes trans-MI[MBr4py2] to trans-MBr4py2. 相似文献