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91.
M. G. Peterleitner D. A. Valyaev L. N. Novikova O. V. Semeikin N. A. Ustynyuk 《Russian Journal of Electrochemistry》2003,39(11):1270-1277
Oxidative dehydrodimerization of some phenylvinylidene complexes of manganese is studied by cyclic voltammetry. In the case of (5-C5H5)(CO)2Mn=C=C(H)Ph, the process occurs as the homolysis of the C–H bond in the radical cation of {(5-C5H5)(CO)2Mn=C=C(H)Ph}+· and the dimerization of intermediate -phenylethinyl cation [(5-C5H5)(CO)2Mn–CC–Ph]+ to a binuclear dication of bis-carbine type (5-C5H5)(CO)2Mn+C– C(Ph)=C(Ph)–CMn+(CO)2(5-C5H5). The reduction of the latter leads to binuclear bis-vinylidene complex (5-C5H5)(CO)2Mn=C=C(Ph)–C(Ph)=C=Mn(CO)2(5-C5H5). Oxidative dehydrodimerization of complexes (5-C5R5)(CO)(L)Mn=C=C(H)Ph (R = H, L = PPh3; R = Me, L = CO) occurs through the immediate C–C coupling of radical cations {(5-C5R5)(CO)(L)Mn=C=C(H)Ph}+· and yields binuclear dication bis-carbine complexes (5-C5R5)(CO)(L)Mn+C–C(H)(Ph)–C(H)(Ph)–CMn+(CO)(L)(5-C5R5), whose reduction leads to neutral compounds (5-C5H5)(CO)2Mn=C=C(Ph)–C(Ph)=C=Mn(CO)(L)(5-C5H5). Complex (5-C5H5)(CO)2Mn=C=C(Ph)–C(Ph)=C=Mn(CO)2(5-C5H5) undergoes the oxidation-induced nucleophilic addition of water, forming cyclic bis-carbene product with a bridge heterocyclic ligand (-3,4-diphenyl-2,5-dihydro-2,5-diylidene)-bis-(5-cyclopentadienyldicarbonyl manganese). 相似文献
92.
The palladium-catalyzed benzylic-like nucleophilic substitution of acetates derived from benzofuran, benzothiophene and indole was investigated. The asymmetric substitution on racemic 1-(2-benzofuryl)ethyl acetate gave disappointing results, but the substitution product was obtained in 98% ee from (S)-1-(2-benzofuryl)ethyl acetate with overall retention of configuration. 相似文献
93.
Micellization ofn-decylamine in aqueous solution leads to substantial decrease in its pK
a, and increase in its reactivity in the nucleophilic substitution ofp-nitrophenylic esters of carboxylic acids (up to 70 times compared to ethylamine which forms no micelles). The influence of cetylpyridinium bromide on the acid-base properties ofn-decylamine and its reactivity was investigated. It was found that the reaction withn-decylamine can be accelerated or retarded depending on the hydrophobicity of the esters. The quantitative characteristics of the mieellar catalytic processes were estimated.Translated fromIzvestiya Akademii Nauk Seriya Khimicheskaya, No. 2, pp. 366–370, February, 1996. 相似文献
94.
Yuan Yuan Wang Wei Li Li Yi Dai 《中国化学快报》2007,18(10):1187-1190
Cationic ring-opening polymerization of 3,3-bis(chloromethyl)oxacyclobutane catalyzed by BF_3·OEt_2 was carried out in ionic liquids [bmim]BF_4 and [bmim]PF_6.The influences of BCMO concentration and molar ratio of BCMO/BF_3·OEt_2 on the molecular weights and yield of PBCMO were investigated.The polymerization in ionic liquids proceed to high conversions,although molecular weights are limited,similar to polymerization in organic solvent such as CH_2Cl_2.Follow a viewpoint of green chemistry, we feel ionic liquid [bmim]BF_4 is superior to [bmim]PF_6.Extracting [bmim]PF_6 from the product using organic solvent as extractant limits its advantage as a green reaction media. 相似文献
95.
A
modulated dsc study on the in situ polymerization of cyclic butylene terephthalate
oligomers 总被引:1,自引:0,他引:1
Z. A. Mohd Ishak P. P. Shang J. Karger-Kocsis 《Journal of Thermal Analysis and Calorimetry》2006,84(3):637-641
The polymerization of a cyclic butylene terephthalate
(CBT) oligomer was studied as a function of temperature (T=200
and 260°C, respectively) by modulated DSC (MDSC). The first heating was
followed by cooling after various holding times (5, 15 and 30 min) prior to
the second heating which ended always at T=260°C.
This allowed us to study the crystallization and melting behavior of the resulting
polybutylene terephthalate (PBT), as well. In contrary to the usual belief,
the CBT polymerization is exothermic and the related process is superimposed
to that of the CBT melting. The melting behavior of the PBT was affected by
the polymerization mode (performed below or above the melting temperature
of the PBT product) of the CBT. Annealing above the melting temperature of
PBT yielded a product featuring double melting. This was attributed to the
presence of crystallites with different degrees of perfection. The crystals
perfection which occurred via recrystallization/remelting was manifested by
a pronounced exothermic peak in the non-reversing trace. 相似文献
96.
T. I. Vakul’skaya I. A. Titova L. I. Larina O. N. Verkhozina G. V. Dolgushin V. A. Lopyrev 《Chemistry of Heterocyclic Compounds》2006,42(11):1427-1434
The vicarious nucleophilic substitution of hydrogen in symmetrical and vicinal nitrotriazoles by 1,1,1-trimethylhydrazinium
iodide in t-BuOK/DMSO was studied by ESR. In the ESR monitoring of the reactions the primary radical-anions of 4-nitro-2-phenyl-1,2,3-triazole
and 1-methyl-3-nitro-1,2,4-triazole were detected and characterized. It was shown by NMR that the amination of 4-nitro-2-phenyl-1,2,3-triazole
takes place exclusively in the triazole ring with the formation of 5-amino-4-nitro-2-phenyl-1,2,3-triazole. 1-Methyl-3-nitro-1,2,4-triazole,
like 3-nitro-1,2,4-triazole, does not form amination products. A possible mechanism for the vicarious C-amination of nitrotriazoles
and the formation of the radical-anions of the substrates is discussed.
Dedicated to Academician M. G. Voronkov on his 85th birthday.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1662–1670, November, 2006. 相似文献
97.
Surprising Reactions on O-Methyl-1,1-dithiooxalates The O-methyl-1,1-dithiooxalate ligand (i-dtoMe) reacts with metalII-acetylacetonates of d8 metal centers (NiII, PdII) forming mononuclear mixed ligand complexes with two remarkable aspects: The formation of a perthioligand, first time described for thiooxalates, and the first example of a nucleophilic attack of a CH-acidic compound (acetylacetonate) on dithiocarbon of coordinated dithiocompounds (here i-dtoMe). X-ray structure is shown for Ph4P[(ptoMe)Ni(i-dtoMeacac)]. 相似文献
98.
99.
Beresnev D. G. Rusinov G. L. Ponomareva A. Yu. Chupakhin O. N. 《Russian Chemical Bulletin》2003,52(10):2161-2166
Recyclization of the addition products of alkylureas to 3-aryl-1,2,4-triazin-5(2H)-ones affording 1,2,4-triazole derivatives was found to occur in Ac2O. 相似文献
100.
在Novozyme 435脂肪酶催化下, 甲基丙烯酸羟乙酯(HEMA)引发己内酯(ε-CL)开环聚合反应, 得到一端为双键, 另一端为羟基的直链聚己内酯(PCL)产物; 将其端羟基官能化得到大分子AB*型单体, 与苯乙烯以原子转移自由基聚合(ATRP)反应形式进行自缩合乙烯基共聚合, 得到超支化结构聚苯乙烯-b-聚己内酯产物. 相似文献