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111.
Polarized IR spectra of five benzene derivatives (four of C2v symmetry and one of D2h symmetry) have been recorded using the stretched polymer method. It has been found that the values of the dichroic ratios depend systematically on the symmetry class of the vibration in question. The IR-active vibrations can thus be unambiguously divided into the correct symmetry classes. The general validity of the method, as well as its value for vibrational analysis, is discussed. 相似文献
112.
A gate to organokrypton chemistry: HKrCCH 总被引:1,自引:0,他引:1
Khriachtchev L Tanskanen H Cohen A Gerber RB Lundell J Pettersson M Kiljunen H Räsänen M 《Journal of the American Chemical Society》2003,125(23):6876-6877
An organic molecule containing krypton, HKrCCH, is reported. The preparation of HKrCCH includes 193-nm photolysis of H2C2/Kr solid mixtures at 8 K and subsequent thermal mobilization of hydrogen atoms at >/=30 K. The identification is based on infrared absorption spectroscopy and supported by ab initio calculations which show ionic and covalent contributions to the bonding. We believe that a series of similar organokrypton molecules can be prepared as computationally demonstrated for HKrC4H and HKrC3H3. These results feature a generally novel way for activating chemically the H-CC- group, which can find practical applications of the krypton catalysis. 相似文献
113.
Yves Charreire Robert Cortes E. Nyk?nen L. Niinist? P. Soininen Markku Leskel? 《Fresenius' Journal of Analytical Chemistry》1998,362(1):41-50
Extended X-ray absorption fine structure (EXAFS) was used to determine the local structure of the luminescent centers in
Tb3+ and Ce3+ -doped strontium sulfide thin films deposited by Atomic Layer Epitaxy (ALE). The rare earths were observed to enter mainly
the substitutional sites but at the same time a part of the atoms form RES clusters (RE = rare earth). The presence of both
substitutional sites and RES clusters has been observed for the first time in this study for rare earths in II–VI compounds.
Received: 9 February 1998 / Revised: 22 May 1998 / Accepted: 29 May 1998 相似文献
114.
Aapo U. Hrknen Markku Ahlgrn Tapani A. Pakkanen Jouni Pursiainen 《Journal of organometallic chemistry》1997,530(1-2):191-197
Three tetranuclear clusters [Ru4H4(CO)11(PPh3)] (1), [Ru4H2(CO)12(PPh3)] (2) and [Ru3IrH(CO)12(PPh3)] (3) were formed in the reaction of [Ir(CO)Cl(PPh3)2] and Na[Ru3H(CO)11] in tetrahydrofuran. Complexes 1–3 were characterized by IR and 1H and 31P NMR, and the structure of the clusters was confirmed by single crystal X-ray analysis. In 2 and 3 one of the carbonyls bridges between two ruthenium atoms; otherwise the compounds contain only terminal carbonyls. 相似文献
115.
Konu J Ahlgrén M Aucott SM Chivers T Dale SH Elsegood MR Holmes KE James SL Kelly PF Laitinen RS 《Inorganic chemistry》2005,44(14):4992-5000
The reaction of (Me3SiNSN)2S with TeCl4 in CH2Cl2 affords Cl2TeS2N2 (1) and that of (Me3SiNSN)2Se with TeCl4 produces Cl2TeSeSN2 (2) in good yields. The products were characterized by X-ray crystallography, as well as by NMR and vibrational spectroscopy and EI mass spectrometry. The Raman spectra were assigned by utilizing DFT molecular orbital calculations. The pathway of the formation of five-membered Cl2TeESN2 rings by the reactions of (Me3SiNSN)2E with TeCl4 (E = S, Se) is discussed. The reaction of (Me3SiNSN)2Se with [PPh4]2[Pd2X6] yields [PPh4]2[Pd2(mu-Se2N2S)X4] (X = Cl, 4a; Br, 4b), the first examples of complexes of the (Se2N2S)2- ligand. In both cases, this ligand bridges the two palladium centers through the selenium atoms. 相似文献
116.
Jan Moncol Maria Korabik Peter Segl'a Dr. Marian Koman Dušan Mikloš Jana Jašková Tadeusz Glowiak Milan Melník Jerzy Mrozinski Markku R. Sundberg 《无机化学与普通化学杂志》2007,633(2):298-305
The characterization of the complexes [Cu2(2‐Clnic)4(H2O)2] ( 1 ), [Cu(2,6‐Cl2nic)2(H2O)2] ( 2 ) and [Cu(5‐Brnic)2(H2O)2]n ( 3 ) (where 2‐Clnic = 2‐chloronicotinate, 2,6‐Cl2nic = 2,6‐dichloronicotinate or 5‐Brnic = 5‐bromonicotinate) was based on elemental analysis, IR, electronic and EPR spectra, and magnetic susceptibility. Complex 1 was also studied by X‐ray analysis at 298 1a and 80 K 1b . The complex 1 contains a dinuclear Cu‐acetate molecular structure in which the carboxyl groups of the 2‐chloronicotinate ligands act as bridges and water molecules are at apical positions. The stereochemistry about Cu atom at both temperatures is typical for square pyramidal geometry with CuO4O chromophore. The Cu‐Cu distance is 2.6513(8) and 2.6382(6) Å for 1a and 1b , respectively. The Cu atoms are displaced by 0.2069(9) and 0.1973(7) Å, respectively, from the plane containing four oxygen atoms bonded to the Cu atom toward the apical water molecules. Strong and weak hydrogen bonds as well as C–Cl···π interactions in the crystal structure are discussed as well. Both complexes, monomeric [Cu(2,6‐Cl2nic)2(H2O)2] ( 2 ) and polymeric [Cu(5‐Brnic)2(H2O)2]n ( 3 ), possess octahedral copper(II) stereochemistry with differing tetragonal distortions. 相似文献
117.
Karoliina Joutsiniemi Markku Ahlgrn Pirjo Vainiotalo Olaf Morgenstem Mario Meusel 《Journal of heterocyclic chemistry》1995,32(1):283-290
The mass spectra of ten 1,3-dithioxo[1,2,4]triazolo[1,2,-b]phthalazines, five 3-iminosubstituted 1-thioxo-[1,3,4]thiadiazolo[3,4-b]phthalazines, three 3-iminosubstituted-1-thioxo[1,2,4]triazolo[1,2-b]phthalazines, and 1,3-dithioxo-5,10-dihydro[1,3,4]thiadiazolo[3,4-b]phthalazine were recorded under electron ionization. The fragmentation pathways were elucidated by metastable ion analysis and exact mass measurements. The changes in the ring-system had little effect on the fragmentation mechanism, but the effect on peak intensities was considerable. The most important fragmentations began with the opening of the triazole ring. Substituents at nitrogen atoms also had a marked effect on the mass spectral behavior. The aryl substituents prompted a whole new fragmentation. The X-ray crystal structure was determined for a few compounds. Two of the three structures of the 1,3-dithioxo[1,2,4]triazolo[1,2-b]phthalazines that were studied proved to be relatively planar, whereas the structure of 1,3-dithioxo-5,10-dihydro[1,3,4]thiadiazolo[3,4-b]phthalazine was considerably bent similarly to the 2-(4-chlorophenyl)-1,3-dithioxo-2,3,5,10-tetrahydro[1,2,4]triazolo[1,2-b]-phthalazine. The triazole and the thiadiazole rings had a strong double bond nature. 相似文献
118.
Khriachtchev L Isokoski K Cohen A Räsänen M Gerber RB 《Journal of the American Chemical Society》2008,130(19):6114-6118
A novel noble-gas compound, HXeOXeH, is identified using IR spectroscopy, and it seems to be the smallest known neutral molecule with two noble-gas atoms. HXeOXeH is prepared using, for example, UV photolysis of water in solid xenon and subsequent annealing at 40-45 K. The experimental observations are fully supported by extensive quantum chemical calculations. A large energy release of 8.3 eV is computationally predicted for the decomposition of HXeOXeH into the 2Xe + H2O global energy minimum. HXeOXeH may represent a first step toward the possible preparation of (Xe-O)n chains and it may be relevant to the terrestrial "missing xenon" problem. 相似文献
119.
Markku Kaikkonen 《Designs, Codes and Cryptography》1998,15(2):183-186
It is shown that A(22,10) 50, A(23,10) 76, A(25,10) 166, A(26,10) 270, A(29,10) 1460, and A(28,12) 178, where A(n,d) denotes the maximum cardinality of a binary code of length n and minimum Hamming distance d. The constructed codes are invariant under permutations of some affine (or closely related) permutation group and have been found using computer search. 相似文献
120.
Raija Oilunkaniemi Jarkko Pietikinen Risto S. Laitinen Markku Ahlgrn 《Journal of organometallic chemistry》2001,640(1-2):50-56
Triphenyltelluronium hexachloroplatinate (1), hexachloroiridate (2), tetrachloroaurate (3), and tetrachloroplatinate (4) were prepared from Ph3TeCl and potassium salts of the corresponding anions. Upon recrystallization of 4 from concentrated nitric acid, K2[PtCl6] and (Ph3Te)(NO3)·HNO3 (5) were obtained. The crystal structures of 1–3 and 5 are reported. Compounds 1 and 2 are isostructural. They are triclinic, P
, Z=2 (the asymmetric unit contains two formula units). Compound 1: a=10.7535(2), b=17.2060(1), c=21.4700(3) Å, =78.9731(7), β=77.8650(4), γ=78.8369(4)°. Compound 2: a=10.7484(2), b=17.1955(2), c=21.4744(2) Å, =78.834(1), β=77.649(1), γ=78.781(1)°. Compound 3 is monoclinic, P21/c, Z=4, a=8.432(2), b=14.037(3), c=17.306(3) Å, β=93.70(3)°. Compound 5 is monoclinic. P21/n, Z=4, a=9.572(2), b=14.050(3), c=13.556(3) Å, β=90.76(3)°. The primary bonding in the Ph3Te+ cation in each salt is a trigonal AX3E pyramid with Te---C bond lengths in the range 2.095(8)–2.14(2) Å and the bond angles 94.1(6)–100.9(5)°. The weak TeCl (1–3) and TeO (5) secondary interactions expand the coordination sphere. In 1 and 2 the cation shows a trigonal bipyramidal AX3YE coordination with one primary Te---C bond and the shortest secondary TeCl contact in axial positions and the two other Te---C bonds and the lone-pair in equatorial positions. The cation in 3 shows a distorted octahedral AX3Y3E environment and that in 5 is a more complex AX3Y3Y′2 arrangement. In both latter salts the structure is a complicated three-dimensional network of cations and anions. 相似文献