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41.
The readily available homochiral ligand (1) was used to prepare four mononuclear nickel and cobalt complexes with a 2:1 ligand:metal ratio. X-ray crystal structures of these revealed that in all cases the N,N,O-tridentate ligand adopts facial coordination to the metal with the pyridine rings trans-disposed and the carboxylate and amine groups cis. The individual crystal structures of these compounds differ significantly in the way the complexes pack, which is mediated by hydrogen bonding involving the cations, anions and water molecules as well as, in one case, π-stacking. 相似文献
42.
Four copper(II) complexes (1–4) and a cobalt(II) complex (5) derived from 4-bromo-2-(hydroxymethyl)pyridine (L1) or 5-bromo-2-hydroxymethyl)pyridine (L2) with Cu(NO3)2·3H2O, CuCl2·2H2O and CoCl2·6H2O have been synthesized and their respective crystal structures studied. They show specific influences owing to the different kind of metal cations and counter anions, the hydration as well as the different position of the bromine substitution on both the coordination of the complex unit and the network structure of the crystal lattice. The Cu(II) complexes of L1 are five-coordinate [Cu(L1)2NO3]NO3·H2O (1) and [Cu(L1)2Cl]Cl·H2O (2) species with distorted quadratic pyramidal and trigonal bipyramidal coordination geometries of the N2O3 and N2O2Cl donor atoms around the Cu(II), respectively. The Cu(II) complexes of L2 are six-coordinate [Cu(L2)2(NO3)2] (3) and [Cu(L2)2Cl(H2O)]Cl·H2O (4) species with distorted octahedral coordination geometries of the N4O2 and N2O3Cl donor atoms. A distorted octahedral coordination geometry of the N2O2Cl2 donor atoms is also found in the complex unit [Co(L2)2Cl2] of the Co(II) complex 5 but showing the oxygen atoms of the chelating ligand as well as the chloride ions in a cis-position. Depending on the complex, water molecules and chloride anions are shown to act as stabilizing components of the crystal structure. The comparative structural investigation includes also known structures of the bromine-free ligand analogue 2-(hydroxymethyl)pyridine, illustrating the basic implication of the bromine substitution, mostly perceptible in the different modes of crystal packing. 相似文献
43.
Uroš Urši? 《Tetrahedron》2008,64(42):9937-9946
New, highly functionalised (1E,3E)-1-(benzoylamino)-4-(dimethylamino)buta-1,3-diene-1,2,3-tricarboxylates proved to be useful and versatile reagents in the formation of highly substituted pyridine, N-aminopyridine, pyrrole and pyrido[3,4-c]pyridazine derivatives. The formation of the particular type heterocyclic system is dependent on the starting (1E,3E)-1-(benzoylamino)-4-(dimethylamino)buta-1,3-diene-1,2,3-tricarboxylate. By an appropriate choice of different ester groups it is possible to drive the reactions towards the formation of either pyridine or pyrrole derivatives. 相似文献
44.
氯铝酸离子液体的酸性及其催化烷基化反应研究 总被引:3,自引:0,他引:3
分别采用吡啶探针和乙腈探针红外光谱法研究了氯铝酸离子液体的酸性,结合固体酸表征方法,研究了离子液体的酸性对吡啶探针各振动模式的影响。发现当氯铝酸离子液体AlCl3的摩尔分数x为0.4~0.5时,离子液体显弱Lewis酸性,强碱性吡啶探针分子能很好地表征离子液体的酸性,而弱碱性乙腈探针分子只适用于表征酸性较强的离子液体。考察了氯铝酸离子液体酸强度对苯与长链烯烃烷基化反应的影响,结果发现,AlCl3的摩尔分数x≤ 0.5时,离子液体没有催化活性;x>0.55时,随着离子液体酸性的增强,烯烃转化率升高,但2位烷基苯选择性下降。结合离子液体的酸强度对烷基化反应机理进行初步分析认为具有催化活性的物质是强Lewis酸Al2Cl-7。 相似文献
45.
Krishna C. Majumdar Uday K. Kundu Swapan K. Samanta Nirmal K. Jana 《Monatshefte für Chemie / Chemical Monthly》2003,134(8):1137-1143
Summary. Two hitherto unreported pyrimidine annelated heterocycles were synthesized from 6-cyclopent-2-enyl-5-hydroxy-1,3-dimethylpyrimidine-2,4(1H,3H)-dione and 5-cyclopent-2-enyl-6-hydroxy-1,3-dimethylpyrimidine-2,4(1H,3H)-dione by reaction with pyridine hydrotribromide or hexamethylenetetramine hydrotribromide. The first one was also obtained by reaction with concentrated sulfuric acid.Received October 28, 2002; accepted October 30, 2002
Published online June 2, 2003 相似文献
46.
Alig Robin Karine Julienne Jean Claude Meslin David Deniaud 《Tetrahedron letters》2004,45(52):9557-9559
Substituted pyridones and pyridines have been synthesised efficiently by employing iminium salt as a key precursor. These compounds were prepared using tandem [4+2] cycloaddition/deamination between azabutadiene and dienophiles. 相似文献
47.
Gavin D. Henry Author Vitae 《Tetrahedron》2004,60(29):6043-6061
48.
The effect of a roughening procedure on surface-enhanced Raman scattering (SERS) intensity of pyridine at copper and gold electrodes subjected to negative potential has been investigated. Among four procedures tested for a copper electrode the one consisting of electrochemical activation in a solution of LiCl and CuCl2 resulted in the most stable and effective surface. It was proved that the presence of pyridine during the pretreatment procedure caused a very fast, irreversible decay of SERS intensity for both copper and gold electrodes. Quite stable, at least at room temperatures, gold surfaces were obtained by oxidation-reduction cycles activation in KCl solution. 相似文献
49.
Taking the regio‐ and chemoselectivities of our iron complex precursors with pyridine core in aerobic oxidations into account, we envisioned a more effective influence on catalytic properties by the introduction of different substituents in 4‐position of the pyridine moiety. The synthesis of these novel 4‐substituted (pyridine‐2,6‐diyl)dipropanoic acids 4 is described. Analogously to the unsubstituted derivative, ligands 4 reacted with Fe(ClO4)3 to form trinuclear Fe3(μ3‐O) complexes 3 , which were tested in the aerobic Gif‐type oxidation of α‐pinene to myrtenol, verbenone, myrtenal, and pinene oxide. The electronic nature of the substituents was found to slightly effect the ratio of allylic oxidation/epoxidation, whereas its influence on the oxidation preference of secondary to primary C? H bonds is negligible as compared to the unsubstituted complex. 相似文献
50.
Jing Xu Yibao Li Lejia Wang Xiaoyang Zhu Xunwen Xiao Yanfang Geng Ke Deng Qingdao Zeng 《中国化学快报》2019,30(3):767-770
Because of the effect of pyridine on the substituent position on the TTF group, TTF derivatives exhibit different assembly structures at the interface, which will be of great significance to the construction of functional nanostructures from the molecular design point of view. 相似文献