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971.
É. B. Coropceanu A. P. Rija V. N. Shafranskii O. A. Bologa M. Gdaniec S. T. Malinovskii 《Journal of Structural Chemistry》2007,48(6):1110-1117
The complexes [Co(DH)2(Sam)2]2[ZrF6]·5H2O (I) and [Co(DH)2(Sam)2][BF4]·H2O (II), where DH? is the dimethylglyoxime monoanion, and Sam is para-aminobenzenesulfamide (sulfanilamide, white streptocid), were synthesized, and their crystal structures were determined by X-ray diffraction analysis. The coordination polyhedron of the Co3+ atom is an N6 octahedron formed by four nitrogen atoms of the two dimethylglyoxime residues and two nitrogen atoms of the Sam fragments. The latter are realized in virtually parallel orientation relative to the polyhedron of the metal atom and its equatorial plane; the average value of the dihedral angles is 26.8(1)°, and there is π-π interaction between the benzene rings of the Sam fragments and the π delocalized equatorial metallocycle. The deviation of the cobalt atom from the four-angle plane is up to 0.009(1) Å. The (Co-N)DH? and (Co-N)Sam distances in the [Co(DH)2(Sam)2]+ complex cations vary from 1.892(2) Å to 1.907(3) Å and from 2.000(2) Å to 2.012(2) Å, respectively. The [ZrF6]2? and [BF4]? complex anions play the major role in crystal formation; they produce a substantial effect on the formation of a complex system of hydrogen bonds. 相似文献
972.
Chandra S Kumar A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(5):1410-1415
Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L(1)) and semicarbazone (L(2)) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L)(2)(SO(4)) and Cu(L)(2)(SO(4)) [where L=L(1) and L(2)] which are of five coordinated square pyramidal geometry. 相似文献
973.
The synthesis, characterization and catalytic activity of a series of tetra-halo-dimethyl salen and di-halo-tetramethyl-salen ligands are reported in this paper: α,α′-dimethyl-Salen (dMeSalen) (L1); 3,3′,5,5′-tetrachloro-α,α′-dimethyl-Salen, (tCldMeSalen) (L2); 3,3′-dibromo-5,5′-dichloro-α,α′-dimethyl-Salen, (dCldBrdMeSalen) (L3); 3,3′,5,5′-tetrabromo-α,α′-dimethyl-Salen, (tBrdMeSalen) (L4); 3,3′,5,5′-tetraiodo-α,α′-dimethyl-salen, (tIdMeSalen) (L5); 3,3′-dichloro-5,5′,α,α′-tetramethyl-Salen (dCltMeSalen) (L6); 3,3′-dibromo-5,5′,α,α′-tetramethyl-Salen (dBrtMeSalen) (L7); and 3,3′-diiodo-5,5′,α,α′-tetramethyl-Salen (dItMeSalen) (L8) (Salen = bis(salicylaldehyde)ethylenediamine). Upon reaction with Co(II) ions, these ligands form complexes with square planar geometry that have been characterized by elemental analysis, cyclic voltammetry, UV–Vis, IR and EPR spectroscopies. In the presence of pyridine the obtained Co(II) complexes were found able to bind reversibly O2, which was shown by EPR spectroscopy and cyclic voltammetry. They were also found able to catalyze the oxidation of 2,6-di-tert-butylphenol (DtBuP) (9) with formation of 2,6-di-tert-butyl-1,4-benzoquinone (DtBuQ) (10) and 2,6,2′,6′-tetra-tert-butyl-1,1′-diphenobenzoquinone (TtBuDQ) (11). These properties are first influenced by the coordination of pyridine in axial position of the Co(II) ion that causes an increase of the electronic density on the cobalt ion and as a consequence a decrease in the E1/2 value and an increase of the reducing power of the Co(II) complex. It is noteworthy that, under those conditions the complexes also show a remarkable quasi-reversible behaviour. Second, complex properties are also influenced by the substituents (methyl and halogen) grafted on the aromatic ring and on the azomethynic groups. The donating methyl substituent on the azomethynic groups causes a decrease in the E1/2 value, whereas the halogen substituents on the aromatic rings have two effects: a mesomeric donating effect that tends to lower the redox potential of the complex, and a steric effect that tends to decrease the conjugation of the ligand and then to increase the redox potential of the Co(II) complex. In pyridine, the steric effect predominates, which causes both an increase of the redox potential and a decrease of the selectivity of the oxidation of phenol 9. As a result of all these effects, it then appears that the best catalysts to realize the selective oxidation of 2,6-di-tert-butyl-phenol (9) by O2 are the Co complexes of ligands bearing CH3 donating substituents, Co(dMeSalen) 1 (2CH3 substituents), and Co-di-halo-tetra-methyl-salen complexes 6, 7 and 8 (4CH3 substituents), in the presence of pyridine. 相似文献
974.
Brajagopal Samanta Joy Chakraborty R.K. Bhubon Singh Manas K. Saha Stuart R. Batten Paul Jensen M. Salah El. Fallah Samiran Mitra 《Polyhedron》2007
Two new cyano bridged Cu–Co and Cu–Fe trinuclear bimetallic assemblies, [(CuL)[Co(CN)6](CuL)]ClO4 · 3.5H2O (1) and [(CuL)[Fe(CN)6](CuL)] · 13H2O (2) where [L = (3E,5E)-N1,N4-bis((pyridin-2-yl)methylene)butane-1,4-diamine] have been prepared using cyanometallates as anion precursors and characterised by elemental analyses, spectroscopic studies, single crystal X-ray diffraction and cryomagnetic susceptibility measurements. Magneto-structural correlations have been drawn from cryomagnetic susceptibility measurements over a wide temperature range (2–300 K) under 0.5 T magnetic fields. Weak antiferromagnetic interactions with J = −0.81 and −0.73 cm−1 are found for 1 and 2, respectively, showing a very weak coupling, as expected from the diamagnetic long chain –NC–Co–CN–CN– and –NC–Fe–CN–CN– bridges revealed from the single crystal X-ray diffraction studies. 相似文献
975.
Raul Cardoso Gil Wilder Carrillo‐Cabrera Martin Schultheiss Karl Peters Hans Georg von Schnering Yuri Grin 《无机化学与普通化学杂志》1999,625(2):285-293
The compounds Ba4Ag2Si6, Eu4Ag2Si6, and Ca4Ag2Si6, prepared from the elements at 1273 K (the components in inner corundum crucibles are enclosed in sealed quartz ampoules), are brittle semiconductors with silvery luster. They react slowly with acids liberating hydrogen. Ba4Ag2[Si6] and Eu4Ag2[Si6] crystallize like Ba4Li2[Si6] (space group Fddd (No. 70); a = 8.613 Å, b = 14.927 Å, c = 19.639 Å, and a = 8.420 Å, b = 14.585 Å, c = 17.864 Å, respectively), whereas Ca4Ag2[Si6] represents a new structure type (space group Fmmm (No. 69); a = 8.315 Å, b = 14.391 Å, c = 8.646 Å). The three compounds are Zintl phases with the formal charges M2+, Ag+ and [Si6]10–. The mean bond lengths d(Si–Si) = 2.335–2.381 Å in the 10π‐Hückel arene [Si6]10– as well as d(Ag–Si) = 2.464–2.595 Å vary with the size of the M2+ cations. The chemical bonding was analyzed in terms of the Electron Localization Function (ELF) and compared with the bonding in related systems (Ce4Co2Si6). 相似文献
976.
Co3O4 nanorods have been synthesized at 160℃ for 10 h in the solution of oleic and n-cetane by an emulsion-solvothermal method using Co(NO3)2·6H2O as starting materials. The as-prepared product was characterized by X-ray powder diffraction(XRD),transmission electron microscope(TEM),and vibrating sample magnetometer(VSM). The formation mechanism of the prepared product was analyzed based on formation of rod-like micelles of oleic acid. Cobalt ions can migrate into the micelle core for the nucleation and growth of Co3O4 . The results show that the as-prepared Co3O4 nanorods are with the average size 25×100 nm and in the cubic phase. The magnetic susceptibility meets about linearly with the applied magnetic field at room temperature,and the coercivity (Hc)and remanent magnetization(Ms)values of the product at room temperature are 353 Oe and 0.4 emu/g,respectively. This simple route is also expanded to synthesize other materials with the rod-like morphology. 相似文献
977.
978.
A pair of cobalt(II)-based hydrogen-bonded organic frameworks (HOFs), [Co(pca)2(bmimb)]n (1) and [Co2(pca)4(bimb)2] (2), where Hpca = p-chlorobenzoic acid, bmimb = 1,3-bis((2-methylimidazol-1-yl)methyl)benzene, and bimb = 1,4-bis(imidazol-1-ylmethyl)benzene were hydrothermally synthesized and characterized through infrared spectroscopy (IR), elemental and thermal analysis (EA), power X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD) analyses. X-ray diffraction structural analysis revealed that 1 has a one-dimensional (1D) infinite chain network through the deprotonated pca− monodentate chelation and with a μ2-bmimb bridge Co(II) atom, and 2 is a binuclear Co(II) complex construction with a pair of symmetry-related pca− and bimb ligands. For both 1 and 2, each cobalt atom has four coordinated twisted tetrahedral configurations with a N2O2 donor set. Then, 1 and 2 are further extended into three-dimensional (3D) or two-dimensional (2D) hydrogen-bonded organic frameworks through C–H···Cl interactions. Topologically, HOFs 1 and 2 can be simplified as a 4-connected qtz topology with a Schläfli symbol {64·82} and a 4-connected sql topology with a Schläfli symbol {44·62}, respectively. The fluorescent sensing application of 1 was investigated; 1 exhibits high sensitivity recognition for Fe3+ (Ksv: 10970 M−1 and detection limit: 19 μM) and Cr2O72− (Ksv: 12960 M−1 and detection limit: 20 μM). This work provides a feasible detection platform of HOFs for highly sensitive discrimination of Fe3+ and Cr2O72− in aqueous media. 相似文献
979.
羟胺是典型的显影剂和防氧化剂,研究它的氧化反应机理是很有意义的。前文在HAc-NaAc(pH-3.9-5.0)介质中的研究发现,当Σ[Fe3+]<3×10-6mol·L-1时,铁离子催化十二钨酸络钴酸钾K5[CoW12O40](简记为Co3+W)。 相似文献
980.
(Ni-Co)-WC复合电极的析氢催化性能 总被引:12,自引:0,他引:12
采用 复合电沉 积方法获 得了( Ni Co) W C 复合电极 ,考 察了 复合 电极 在弱 酸性、碱性 和中性介质 中的析 氢电催化 性能,并 在弱酸性 介质中 进行了电 化学稳定 性实验 . 结果 表明,复 合电极具有优越 的析氢 电催化性 能和良好 的电化 学稳定性 . 相似文献