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排序方式: 共有509条查询结果,搜索用时 15 毫秒
141.
Das N Arif AM Stang PJ Sieger M Sarkar B Kaim W Fiedler J 《Inorganic chemistry》2005,44(16):5798-5804
Two Pt(4)-Fe(2) mixed-metal neutral assemblies, 4 and 5, incorporating four bis(triethylphosphine)platinum(II) centers, two flexible bridging 1,1'-ferrocenedicarboxylates, and two rigid 2,9-phenanthrenediyl (4) or 1,8-anthracenediyl (5) bridges, have been synthesized. X-ray characterization of 4 and 5 reveals the formation of discrete and highly symmetrical heterobimetallic neutral species possessing a rhomboidal and rectangular shape, respectively. The rectangular molecules, 5, could be reversibly oxidized in two two-electron steps, separated by 0.21 V. Spectroelectrochemistry in the UV-vis-NIR region confirms the ferrocene groups as primary oxidation sites; however, the intermediate 5(2+) is EPR silent even at 4 K due to enhanced EPR relaxation involving the oxidizable 1,8-anthracenediyl linkers. 相似文献
142.
Jude H Disteldorf H Fischer S Wedge T Hawkridge AM Arif AM Hawthorne MF Muddiman DC Stang PJ 《Journal of the American Chemical Society》2005,127(34):12131-12139
The design and self-assembly of five new supramolecular complexes (a rectangle, a triangle, a hexagon, and two squares) are described. These assemblies incorporate carborane building blocks and were prepared in excellent yields (>85%). The assemblies and building blocks were characterized with multinuclear NMR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. Isotopically resolved mass spectrometry data confirm the existence of the rectangle, triangle, and hexagon, and NMR data are consistent with the formation of all five assemblies. The X-ray structures of two linear carborane building blocks, 1,12-(4-CC(C(5)H(4)N)(2)-p-C(2)B(10)H(10) (1) and 1,12-(trans-(Pt(PEt(3))(2)I)CC)(2)-p-C(2)B(10)H(10) (2), are reported: 1 is monoclinic, P2(1)/c, a = 10.6791(4) A, b = 8.0091(14) A, c = 11.6796(4) A, beta = 107.8461(15) degrees , V = 950.89(5) A(3), Z = 2; 2 is monoclinic, C2/c, a = 62.1128(10) A, b = 22.0071(3) A, c = 14.0494(2) A, beta = 89.9411(8) degrees , V = 19204.4(5) A(3), Z = 16. Crystals of the linear linker 1 exhibit close pi-pi pyridine and pyridine-B(carborane) interactions, which are discussed. 相似文献
143.
Abbasi MA Ahmad VU Zubair M Nawaz SA Lodhi MA Farooq U Choudhary MI 《Natural product research》2005,19(5):509-515
Phytochemical investigation of Symplocos racemosa resulted in the isolation of a new ethyl substituted glycoside, 1-ethyl brachiose-3'-acetate (1) along with four known compounds ketochaulmoogric acid (2), nonaeicosanol (3), triacontyl palmitate (4) and methyl triacontanoate (5). The substitution of ethyl group on 1 was natural because during the course of extraction and purification ethanol was not used. The structural elucidation of the isolated compounds was based primarily on 1D- and 2D-NMR analysis, including COSY, HMQC, and HMBC correlations. The glycoside 1 and triacontyl palmitate (4) displayed the inhibitory potential against lipoxygenase and urease enzyme, respectively. 相似文献
144.
145.
Copper(II) and zinc(II) complexes of Schiff bases obtained by condensation of amoxicillin and cephalexin with salicylaldehyde/pyridoxal were prepared and characterized by microanalytical, thermogravimetric, magnetic and spectroscopic data. All the complexes were found to be six‐coordinate and containing two water molecules. The electron paramagnetic resonance spectral lines exhibited rhombic distortion from axial symmetry, with g|| > g? > ge, in the copper(II) complexes. The geometry of the zinc(II) complexes appears to be octahedral. All the compounds under investigation showed antibacterial activity. The antibacterial activity showed the following trend: copper(II) complexes > zinc(II) complexes > Schiff base ligands > parent drugs. The copper(II) complexes with the Schiff bases derived from cephalexin showed substantially enhanced activity against Pseudomonas aeruginosa compared with the parent drug. All the copper complexes were also found to be active against kaolin paw oedema, whereas the parent drugs were inactive. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
146.
Dr. Arif Music Dr. Andreas N. Baumann Florian Boser Nicolas Müller Florian Matz Prof. Thomas C. Jagau Dr. Dorian Didier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(13):4322-4326
Readily accessible tetraorganoborate salts undergo selective coupling reactions under blue light irradiation in the presence of catalytic amounts of transition-metal-free acridinium photocatalysts to furnish unsymmetrical biaryls, heterobiaryls and arylated olefins. This represents an interesting conceptual approach to forge C−C bonds between aryl, heteroaryl and alkenyl groups under smooth photochemical conditions. Computational studies were conducted to investigate the mechanism of the transformation. 相似文献
147.
148.
Stacey N Anderson Jason M Richards Hector J Esquer Abby D Benninghoff Atta M Arif Lisa M Berreau 《ChemistryOpen》2015,4(5):590-594
Molecules that can be used to deliver a controlled amount of carbon monoxide (CO) have the potential to facilitate investigations into the roles of this gaseous molecule in biology and advance therapeutic treatments. This has led to the development of light-induced CO-releasing molecules (photoCORMs). A goal in this field of research is the development of molecules that exhibit a combination of controlled CO release, favorable biological properties (e.g., low toxicity and trackability in cells), and structural tunability to affect CO release. Herein, we report a new biologically-inspired organic photoCORM motif that exhibits several features that are desirable in a next-generation photoCORM. We show that 3-hydroxyflavone-based compounds are easily synthesized and modified to impart changes in absorption features and quantum yield for CO release, exhibit low toxicity, are trackable in cells, and can exhibit both O2-dependent and -independent CO release reactivity. 相似文献
149.
150.
A. M. Magerramov A. I. Ismiev K. A. Potekhin R. K. Askerov 《Journal of Structural Chemistry》2014,55(1):151-153
New multicomponent condensation of dimedone, benzaldehyde, acetacetic ester, and allylamine in the 1:2:1:1 molar ratio respectively is revealed. It proceeds with the formation of ethyl-3(allylamino)-9,9-dimethyl-7,11-dioxo-1.5-diphenyl-spiro[5.5]undec-2-en-2-carboxylate whose crystal structure is determined by single crystal X-ray diffraction. 相似文献