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161.
Robin D. Rogers Jerry L. Atwood Marvin D. Rausch David W. Macomber 《Journal of chemical crystallography》1990,20(6):555-560
The crystal structures of (
5-C5H4COMe)M(CO)3Me (M=Mo,W) have been determined. They are not isostructural. M=Mo isP21/c,a=10.205(6),b=14.192(8),c=8.135(6) Å,=93.43(4)° andD(calc)=1.71 g cm–3 forZ=4. M=WisP21/c,a=12.580(7),b=6.830(5),c=13.750(7) Å,=93.72(4)° andD(calc)=2.20 g cm–3 forZ=4. Both have a four-legged piano stool geometry with the substituted carbon making the closest M-C(
5) approach. The methyl group in the M=W derivative is disordered between twotrans-ligand positions. The average bonding parameters for the more accurately determined Mo analog are: Mo-C()5)=2.34(3) Å, Mo-CO=1.98(2) Å, Mo-Me=2.304(4) Å. 相似文献
162.
The crystal structure of LiBr·(CH3OCH2CH2OCH3)2 has been determined from counter data and refined by full-matrix least-squares techniques. The crystals belong to the monoclinic space groupC2/c (C
2h
6
, No. 15) witha=13.518(4),b=8.007(3),c=12.252(4) Å,=98.08(2)°, andD
calc=1.35 gcm–3 forZ=4. The finalR value for 489 observed reflections is 0.033. The lithium and bromine atoms lie on a crystallographic two-fold axis. The structure consists of discrete LiBr·(CH3OCH2CH2OCH3)2 units. The Li-Br separation is 2.57(1) Å. The two DME molecules are coordinated to the lithium atom through the four oxygen atoms at an average LiO separation of 2.09(3) Å. 相似文献
163.
The crystal structure of (5-C5H5)2Hf(1-NC4H4)2 has been determined from X-ray data measured by counter methods. The title compound is isostructural with (5-C5H5)2Zr(1-NC4H4)2, and crystallizes in the monoclinic space groupP21/c (C
2h
5
, No. 14) with unit cell constantsa=9.605(3),b=8.174(3),c=19.487(4) Å, =90.85(3)°, andZ=4 forD
c=1.91 gcm–3. Full-matrix least-squares refinement gave a finalR value of 0.068 for 2154 independent observed reflections. The two cyclopentadienyl rings are 5-coordinated to the hafnium atom at an average Hf-C(5–) distance of 2.51(1) Å. The Hf-N-centroid (-pyrrolyl) angles average 166°. 相似文献
164.
Douglas X. West Christine A. Brown Jerry P. Jasinski John M. Jasinski Rick M. Heathwaite David G. Fortier Richard J. Staples Ray J. Butcher 《Journal of chemical crystallography》1998,28(12):853-860
Structures of the following compounds have been solved: tris(2-thio-6-picoline N-oxide)cobalt(III), [Co(6MOS)3], orthorhombic, Pca21, a = 17.871(3), b = 14.061(2), c = 15.964(2) Å, V = 4011(1) Å3, Z = 8, and = 1.193 mm–1; bis (2-thio-6-picoline N-oxide)nickel(II), [Ni(6MOS)2], orthorhombic, Pbca, a = 15.602(8), b = 13.606(4), c = 13.348(8) Å, V = 2833(4) Å3, Z = 8, and = 1.655 mm–1; bis(2-thio-6-picoline N-oxide)copper(II), [Cu(6MOS)2], orthorhombic, Pbca, a = 13.914(5), b = 12.984(5), c = 15.663(6) Å, V = 2830(2) Å3, Z = 8, and = 1.836 mm–1; and bis(2-thio-6-picoline N-oxide)zinc(II), [Zn(6MOS)2], triclinic, P – 1, a = 7.9737(8), b = 11.7786(9), c = 7.9206(8) Å, = 104.502(7), = 104.495(8), = 93.445(8)°, V = 691.3(1) Å3, Z = 2, and = 2.106 mm–1. The steric effect of the methyl group in the six-position of the N-oxide ring is considered in comparing these structures to complexes of 2-thiopyridine N-oxide. 相似文献
165.
Fumio Hamada G. William Orr Hongming Zhang Jerry L. Atwood 《Journal of chemical crystallography》1993,23(8):681-684
The title compound has been prepared by the addition of bromocalix[4]arene methyl ether to CuCN in N-methylpyrrolidone. The crystals belong to the monoclinic space groupP21/n witha=13.591(3),b=24.778(5),c=11.057(3)Å,=93.58(2)°, andD
c=1.09 g cm–3 forZ=4. Refinement based on 1118 observed reflections led to a finalR value of 0.085. The molecule exhibits the partial cone conformation. 相似文献
166.
Jerry L. Atwood Abbas Alvanipour Hongming Zhang 《Journal of chemical crystallography》1992,22(3):349-352
The title compound has been prepared by the addition of fluoroboric acid to 18-crown-6 in toluene. The compound crystallizes in the triclinic space group P¯1 witha=7.341(2),b=8.364(2),c=10.631(3)Å,=71.48(2),=67.91(2), =67.94(2)°, andD
c
=1.44 g cm–3 forZ=1. The final conventionalR value was 0.079 based on 1575 observed reflections. The molecule resides on a center of inversion. The (H2O·HBF4) moieties are best viewed as fluoroboric acid monohydrate molecules hydrogen bonded to the crown ether, one above and one below the plane of the crown. The FO(water) hydrogen bond separation is 2.474(5)Å, and the O(crown)O(water) separations are 2.834(5) and 2.841(6) Å. The oxygen atoms of the crown ether are planar to 0.23 Å. 相似文献
167.
The structure of the title compound has been confirmed by an X-ray diffraction analysis, and refined by full-matrix least squares. The crystals are mono-clinic:a=9.171(3),b=25.176(15)c=9.192(3) Å,=117.08(3)°,Z=4,D
x
=1.976g cm–3,=2.66mm¯1, space groupP21/n (No. 14). The finalR value is 5.7%. Interatomic distances and bond angles are compared with those reported in related molecules.The preferred name of this compound according to the IUPAC rules is
3-[11–2-bis(trifluoromethyl)vinylene]-
3-carbonyl-tris (-cyclopentadienyl)-triangulo-tricobalt. 相似文献
168.
Parks JM Kondru RK Hu H Beratan DN Yang W 《The journal of physical chemistry. B》2008,112(10):3168-3176
The inter- and intramolecular interactions that determine the experimentally observed binding mode of the ligand (2Z)-2-(benzoylamino)-3-[4-(2-bromophenoxy)phenyl]-2-propenoate in complex with hepatitis C virus NS5B polymerase have been studied using QM/MM calculations. DFT-based QM/MM optimizations were performed on a number of ligand conformers in the protein-ligand complex. Using these initial poses, our aim is 2-fold. First, we identify the minimum energy pose. Second, we dissect the energetic contributions to this pose using QM/MM methods. The study reveals the critical importance of internal energy for the proper energy ranking of the docked poses. Using this protocol, we successfully identified three poses that have low RMSD with respect to the crystallographic structure from among the top 20 initially docked poses. We show that the most important energetic component contributing to binding for this particular protein-ligand system is the conformational (i.e., QM internal) energy. 相似文献
169.
Jerry Ray Dias 《Journal of mathematical chemistry》2008,44(3):711-724
Recent development of the leapfrog operation in enumeration and understanding the chemical properties of benzenoid isomer
sets having at least one synthesized representative is stressed. Some new enumeration results and correlations of the periodic
table for the more stable total resonant sextet (TRS) benzenoid hydrocarbon subset [Table PAH6(sextet)] are presented. 相似文献
170.
Shellhamer DF Davenport KJ Forberg HK Herrick MP Jones RN Rodriguez SJ Sanabria S Trager NN Weiss RJ Heasley VL Boatz JA 《The Journal of organic chemistry》2008,73(12):4532-4538
Reactions of chlorine (Cl(2)) with 4-halo-1,1,2-trifluorobut-1-enes (1, 2, or 3) give open-ion intermediates A and E that are in equilibrium. The open-chloronium ions (E) rearrange to a five-membered-ring halonium ion during ionic chlorination of 3 when the number-4 halo-substituent is iodine. Three-membered-ring bromonium and iodonium ions from alkenes 1, 2, or 3 are rather symmetrical and similar in structure. Quantum chemical calculations show that five-membered-ring halonium ion intermediates are 11 to 27 kcal/mol more stable than the three-membered-ring halonium ions or the open-ions A and E. The five-membered-ring intermediates lead to rearranged products. Rearranged products increase as the number-4 halogen (Z) becomes more nucleophilic (Z: Cl < Br < I). Open chloronium ions from ionic chlorination of terminal fluorovinyl alkenes are compared to the open ions generated by protons to similar alkenes. 相似文献