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971.
George Eng Deborah Whalen Primrose Musingarimi John Tierney Michael DeRosa 《应用有机金属化学》1998,12(1):25-30
In the interest of developing a more effective fungicide to combat Dutch elm disease, our laboratories have synthesized several triphenyltin carboxylates and some 1:1 addition compounds of triphenyltin chloride using 2,3-disubstituted thiazolidin-4-ones as the ligand and screened them in vitro against Ceratocystis ulmi, the causative agent of Dutch elm disease, using a shake culture method. Elemental analyses and spectroscopic data indicate that the structures of the carboxy- lates in the solid state are monomeric with a tetrahedral tin atom with the exception of the furan-2-carboxylic acid derivative, which was found to be polymeric. The triphenyltin chloride adducts are trigonal-bipyramidal with the three phenyl groups in the equatorial plane. Far-infrared data indicate that the three phenyl groups are not co-planar. Screening results for both series of organotins indicate that these two classes of compounds are effective inhibitors of Ceratocystis ulmi, with the adducts having a higher activity. The furan-2-carboxylic acid derivative has a markedly decreased activity compared with the other carboxylates and this is attributed to its polymeric structure. © 1998 John Wiley & Sons, Ltd. 相似文献
972.
973.
Synthesis, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Tetrahalogeno‐bis‐Pyridine‐Osmium(III) Complexes cis ‐( n ‐Bu4N)[OsCl4Py2] and trans ‐( n ‐Bu4N)[OsX4Py2], X = Cl, Br By reaction of (n‐Bu4N)2[OsX6], X = Cl, Br, with pyridine and (n‐Bu4N)[BH4] tetrahalogeno‐bis‐pyridine‐osmium(III) complexes are formed and purified by chromatography. X‐ray structure determinations on single crystals have been performed of cis‐(n‐Bu4N)[OsCl4Py2] ( 1 ) (triclinic, space group P1, a = 9.4047(9), b = 10.8424(18), c = 17.007(2) Å, α = 71.833(2), β = 81.249(10), γ = 67.209(12)°, Z = 2), trans‐(n‐Bu4N)[OsCl4Py2] ( 2 ) (orthorhombic, space group P212121, a = 8.7709(12), b = 20.551(4), c = 17.174(4) Å, Z = 4) and trans‐(n‐Bu4N)[OsBr4Py2] ( 3 ) (triclinic, space group P1, a = 9.132(3), b = 12.053(3), c = 15.398(2) Å, α = 95.551(18), β = 94.12(2), γ = 106.529(19)°, Z = 2). Based on the molecular parameters of the X‐ray structure determinations and assuming C2 point symmetry for the anion of 1 and D2h point symmetry for the anions of 2 and 3 the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants of 1 are in the Cl–Os–Cl axis fd(OsCl) = 1.58, in the asymmetrically coordinated N′–Os–Cl · axes fd(OsCl · ) = 1.45, fd(OsN′) = 2.48, of 2 fd(OsCl) = 1.62, fd(OsN) = 2.42 and of 3 fd(OsBr) = 1.39 and fd(OsN) = 2.34 mdyn/Å. 相似文献
974.
An unprecedented facile oxidation of 1,3,5-trisubstituted pyrazolines and Hantzsch 1,4-dihydropyridines (DHPs) to the corresponding pyrazoles and pyridines was observed, mediated by 3,4-dihydro-2H-pyran in air. The reaction showed excellent reactivity, functional group tolerance, and high yield without using any metal and/or halogen based oxidizing agents. 相似文献
975.
Evaluation of 5‐ethylidene‐2‐norbornene with an adhesion promoter for self‐healing applications 下载免费PDF全文
5‐Ethylidene‐2‐norbornene (ENB) has a potential application as part of a new generation of healing agents, owing to its rapid polymerization rate and wide liquid temperature range. In this study, we developed a new self‐healing system using ENB as the healing agent and methyl 5‐norbornene‐2‐carboxylate (MNC) as the adhesion promoter. Dynamic differential scanning calorimetry (DSC) was used to monitor cure behaviors of ENB with different MNC loadings, through which a series of cure temperatures were designed. The MNC loading and cure temperature had significant effects on the adhesion strength. The adhesion strength increased remarkably with MNC loadings of up to 10 wt % compared with ENB alone. The ENB monomer and the ENB/MNC mixture were successfully microencapsulated, and the resultant microcapsules were embedded into an epoxy resin along with Grubbs' catalyst for self‐healing efficiency measurements. Peak fracture loads for both healing agents showed maximal values at a low catalyst loading (0.3 wt %). In comparison with neat ENB, a significant improvement in healing efficiency was observed for the ENB/MNC mixture. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1170–1179 相似文献
976.
Sergio Fombona Dr. Maialen Espinal‐Viguri Dr. Miguel A. Huertos Dr. Jesús Díaz Dr. Ramón López Dr. M. Isabel Menéndez Dr. Julio Pérez Dr. Lucía Riera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17160-17164
4,4’‐Disubstituted‐2,2′‐bipyridine ligands coordinated to MoII and ReI cationic fragments become dearomatized by an intramolecular nucleophilic attack from a deprotonated N‐alkylimidazole ligand in cis disposition. The subsequent protonation of these neutral complexes takes place on a pyridine carbon atom rather than at nitrogen, weakening an aromatic C?C bond and affording a dihydropyridyl moiety. Computational calculations allowed for the rationalization of the formation of the experimentally obtained products over other plausible alternatives. 相似文献
977.
Mallappa Beerappa 《合成通讯》2018,48(17):2150-2158
A facile synthesis of a series of pyrimidinone derivatives from the reaction of benzyl halides, (1-bromoethyl)benzene and urea in the presence of pyridine N-oxide (PNO) under solvent-free conditions is described. This transformation presumeably occurs via oxidation/cross-aldol condensation/Michael addition/intra molecular cyclization, domino sequence, involving the formation of one C–C bond and two C–N bonds in a single step. 相似文献
978.
H. Wilczura B. Semeniuk A. Myslinski T. Kasprzycka-Guttman 《Journal of Thermal Analysis and Calorimetry》1992,38(9):2011-2018
The molar excess enthalpies measured for binary mixtures of 2-, 3-, 4-picoline +n-alkane (C6H14-C10H22) at 298.15 K have been compared with the Prigogine-Flory-Patterson theory and the Extended Real Associated Solution model estimations.
Zusammenfassung Die bei 298.15 K gemessenen molaren Zusatzenthalpien binärer Mischungen aus 2-,3-,4-Picolin und einemn-Alkan (C6H14-C10H22) wurden mit den nach der Prigonine-Flory-Patterson-Theorie und den nach dem erweiterten Modell real assoziierter Lösungen (ERAS) berechneten Weiten verglichen.相似文献
979.
The crystal and molecular structures of tris(p-anisyl)tin acetate (1) (p-anisyl = p-methoxyphenyl) and trimesityltin acetate (2) (mesityl = 2,4,6-trimethylphenyl) have been determined. Both have monomeric structures with the acetate group acting as an asymmetric bidentate ligand. Bond valence analysis of (1) and (2) and other Ph3SnO2CR suggest however that the carboxylate ligand effectively occupies a single bonding position at tin. Thus in (1) and (2) the tin atom is in a chemical environment equivalent to that found in four-coordinate R3Sn-X systems based on tetrahedral geometry. 相似文献
980.
Damaso Navarro-Rodriguez Yves Frere Philippe Gramain 《Journal of polymer science. Part A, Polymer chemistry》1992,30(12):2587-2594
The kinetics and characteristics of the quaternization of poly(4-vinylpyridine) with very large alkylating agents are studied with the main aim to demonstrate the occurrence of a limitation of the reaction due to steric effect. Kinetics are carried out in sulfolane at different temperatures with two ω-(4'-methoxy-4-biphenylyloxy)alkyl bromides. An important limitation of the reaction is demonstrated: 30% of the pyridine groups are inaccessible at 333 K, 23% at 355.5 K, and 4% at 363 K. Post-quaternization experiments with butyl bromide of already partially quaternized P4VP also demonstrate this limitation. The occurrence of global steric hindrance and hydrophobic effects affecting the conformation of the chain in solution is proposed to explain the limited accessibility of the pyridine groups. The results question the classical neighboring group model generally used to describe the slowing down of the quaternization reaction with increasing quaternization ratio. The thermal stability of the quaternized polymers and the colors of the reaction medium are also discussed. © 1992 John Wiley & Sons, Inc. 相似文献