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41.
A new family of single-stranded helices coordination polymers with mixed ligands, [M2(phen)2(e,a-cis-1,4-chdc)2(H2O)2]n (1, M=Co; 2, M=Ni; chdc=cyclohexanedicarboxylic acid; phen=1,10-phenanthroline), were prepared under hydrothermal conditions and characterized by elemental analyses, IR spectra, TG analysis, and single-crystal X-ray diffraction analysis. X-ray crystal structural analyses reveal that 1 and 2 are isomorphic and belong to the monoclinic system. C40H36Co2N4O10, P2(1)/c, a=10.0566(5) A, b=8.8843(5) A, c=20.2912(14) A, beta=100.052(3) degrees, Z=2 for 1; and C40H36Ni2N4O10, P2(1)/c, a=9.8921(6) A, b=9.0151(4) A, c=20.1628(17) A, beta=100.31(2) degrees, Z=2 for 2. In the structures of 1 and 2, the 1,4-chdc ligand possesses only one kind of e,a-cis-conformation although there are both cis- and trans-conformations in the raw material. Two oxygen atoms of one carboxyl in 1,4-chdc ligand and another oxygen atom of contraposition carboxyl link adjacent Co or Ni atoms into an infinite 1-D zigzag chain. The most attractive structural feature of 1 and 2 is that they both exhibit an infinite chiral chainlike structure with 2(1) helices along the b axis. In addition, the right-handed and the left-handed chains are alternate. Meanwhile, the adjacent chains of 1 and 2 are linked via hydrogen bonds into 2-D network structures, which further form 3-D frameworks via pi-pi interactions of 1,10-phen. 相似文献
42.
43.
Mg-Al spinel (MgAl2O4) nanorods and nanoplatelets transformed from Mg-Al layered double hydroxide (Mg-Al-LDHs) were synthesized via a combined hydrothermal method and calcination route using Al(NO3).9H2O and Mg(NO3)2.6H2O as raw materials. The nanorods and nanoplatelets were characterized by means of physical techniques, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microcopy (HRTEM), selected-area electron diffraction (SAED), Fourier transform infrared spectra (FT-IR), thermogravimetric (TG), and nitrogen adsorption-desorption isotherms. XRD patterns reveal that the Mg-Al-LDHs nanostructures were obtained under a hydrothermal reaction temperature of 200 degrees C and Mg-Al spinel nanostructures were fabricated via calcination of the Mg-Al-LDHs nanostructures at 750 degrees C. It can be seen from TEM that the sizes of the Mg-Al-LDHs nanoplatelets were about 20-40 nm and the diameters of the MgAl2O4 nanorods were ca. 6 nm. The HRTEM images indicate that the crystal lattice spaces of the MgAl2O4 nanorods and nanoplatelets are 0.282 and 0.287 nm, respectively. 相似文献
44.
A versatile heteropoly acid (H3PMo12O40)-catalyzed coupling of diarylmethanols with epoxides was established for the synthesis of polyaryl-substituted aldehydes. Furthermore, the catalytic system was also suitable for the reaction of diarylmethanols and diols/aldehydes. The application of such an earthabundant, readily accessible, and nontoxic catalyst provides a green approach for the construction of polyaryl-substituted aldehydes. 相似文献
45.
Changwen Zhao Xiaoye Gao Pan He Chunsheng Xiao Xiuli Zhuang Xuesi Chen 《Colloid and polymer science》2011,289(4):447-451
A novel and facile strategy has been designed to prepare biodegradable microgels with thermo- and pH-responsive property.
The microgels were synthesized by the crosslinking of N-isopropylacrylamide with vinyl groups functionalized poly(L-glutamic acid) (PGA). The resultant microgels exhibited pH-dependent
phase transition behaviors in aqueous solutions and underwent abrupt lower critical solution temperature decrease when the
pH was reduced below the pK
a of PGA. Dynamic light scattering measurement revealed that the microgels exhibited shrinkage as the temperature increased
or the pH decreased. 相似文献
46.
Molecular assembly processes by utilizing the template-directing effect of anionic polyoxometalate clusters and the flexible organic cation have achieved three hybrids: (H2bpp)(Hbpp)[PMo12O40]·3DMF (1), (H2bpp)(Hbpp)(bpp)2 [PMo9V3O40(VO)2]2 (2), and (H2bpp)2[β-Mo8O26] (3) (bpp = 1,3-bis(4-pyridyl)propane). Three compounds were characterized using single crystal X-ray crystallography, elemental analysis, IR, XPS, EPR, voltammetric behavior and TGA. Crystal structural analyses revealed that compounds 1–3 were all constructed from protonated organic bpp cations with different POM clusters: isolated α-Keggin P–Mo cluster in 1; dimer of bi-capped α-Keggin P–Mo–V anions linked through a {V2O2} unit in 2; β-octamolybdate isopolyanion in 3, respectively. All three assemblies demonstrated a higher thermal stability. The protonated bpp cations lost at temperature higher than 300 °C that the strong intermolecular interactions may account for the high initial temperature of weight loss. The electrochemistry property of compound 2 modified carbon paste electrode was also studied in 1 M H2SO4 aqueous. 相似文献
47.
48.
Mathematical Notes - We correct an error in the paper of Z. Shen, S. Li, and J. Zhang published in [4]. In addition, we give an answer to a question posed by the authors. 相似文献
49.
Heteropoly-complexes K17[Ln(CuW11O39)2].xH2O(Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Dy) were prepared. The properties of the products were investigated by ion-exchange, conductometric titration, IR, UV and X-ray powder diffraction. The results show that the structure of the products is similar to that of U(a-Ge11O39)2 and consistent with the model proposed by Peacock. 相似文献
50.
A power-scaled laser operation of Pr:YLi F4(YLF)crystal at 720.9 nm pumped by a 443.6 nm laser diode(LD)module was demonstrated.The 20 W module was used to pump the Pr:YLF crystal,and a maximum output power of 3.03 W with slope efficiency of 30.04%was obtained.In addition,a 5 W blue LD was also used to pump the Pr:YLF laser,and a maximum output power of 0.72 W was obtained at room temperature.The output power was limited by the wavelength mismatch between the single-emitter LD and the absorption peak of the crystal. 相似文献