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排序方式: 共有123条查询结果,搜索用时 31 毫秒
31.
Wieland Tyrra Dieter Naumann Sigrid Buslei Mikhail M. Kremlev 《Journal of fluorine chemistry》2007,128(7):813-817
A temperature range of −18 °C to room temperature was found to be effective for selective fluoride-mediated cross-coupling reactions of trimethyl(perfluoroalkyl)silanes, Me3SiCF3 and Me3SiC2F5, and alkyl halides, RX (X = Br, I) in the absence of any catalyst. 相似文献
32.
在H3PO4存在下进行了2,3-二甲基-2-丁烯与乙酐的酰化反应,结果表明,H3PO4是室温下催化2,3-二甲基-2-丁烯与乙酐酰化反应的有效催化剂,在H3PO4存在下,酰化产物的收率主要取决于:(a)H3PO4的用量,(b)乙酐的用量;(c)反应温度和(d)反应时间,在适宜反应条件下,所得3,3,4-三甲基-4-戊烯-2-酮(TMP)约为99%,另外还发现,反应体系中加入少量乙酸,不会明显减少酰化产物的收率,乙酐的纯度,反应物的加入顺序对该反应几乎没有任何影响,在有和没有溶剂CH2Cl2的条件下所得酰化产物的收率是可比的。 相似文献
33.
气相色谱法测定农药中间体亚磷酸三甲酯及邻二氯苯的含量李来生(南昌大学应用化学研究所南昌330047)关键词亚磷酸三甲酯农药中间体气相色谱法合成中图分类号O657.71亚磷酸三甲酯作为一种重要的有机合成中间体,被广泛用于合成敌敌畏等多种农药和难燃剂[1... 相似文献
34.
《Polyhedron》2000,19(28)
The reactions of ReO(OEt)Cl2L2, L=py, PPh3 or ReOCl3(Me2S)(OPPh3), with spirohydrophosphorane HP(OCMe2CMe2O)2 – abbreviated here as HPO – in toluene yield ReOCl2(PO)L complexes, L=py (1), PPh3 (2) and OPPh3 (3), respectively. The encountered bidentate phosphite pinacolato (OCMe2CMe2O)POCMe2CMe2O− ligand (PO−) is afforded by means of a spirophosphorane ring-opening reaction. All the pink–violet compounds 1–3 were characterised by NMR, IR and UV–Vis spectroscopies. The structure of trans-ReOCl2(PO)PPh3 (2) was determined crystallographically. The rhenium atom adopts distorted octahedral geometry with a trans multiply bonded terminal oxo ligand (Re–Ot=1.698(2) Å) trans to pinacolate oxygen (Re–O=1.880(2) Å). Two phosphorus atoms as well as two chlorides are mutually in a trans arrangement. 相似文献
35.
Gabriele Albertin Stefano Antoniutti Fabio Bredariol 《Journal of organometallic chemistry》2003,679(2):208-219
Mixed-ligand hydride ReH2(NO)L(PPh3)2 complexes [L=P(OEt)3 or PPh(OEt)2] were prepared by allowing the ReH2(NO)(PPh3)3 species to react with an excess of phosphite. Treatment of ReH2(NO)L(PPh3)2 hydrides with an equimolar amount of aryldiazonium cations ArN2+ gives the mono-aryldiazene [ReH(ArNNH)(NO)L(PPh3)2]BPh4 complexes (Ar=C6H5, 4-CH3C6H4), while treatment with an excess of ArN2+ yields bis(aryldiazene) [Re(ArNNH)2(NO)L(PPh3)2](BPh4)2 derivatives. Binuclear [{ReH(NO)L(PPh3)2}2(μ-HNNArArNNH)](BPh4)2 and [{Re(4-CH3C6H4NNH)(NO)L(PPh3)2}2(μ-HNNArArNNH)](BPh4)4 complexes (ArAr=4,4′-C6H4C6H4, 4,4′-C6H4CH2C6H4) were also prepared. The reaction of the triphenylphosphine ReH2(NO)(PPh3)3 complex with aryldiazonium cations was studied and led exclusively to mono-aryldiazene [ReH(ArNNH)(NO)(PPh3)3]BPh4 and [{ReH(NO)(PPh3)3}2(μ-HNNArArNNH)](BPh4)2 derivatives. The complexes were characterised spectroscopically (IR, NMR) using the 15N-labelled derivatives. The aryldiazenido [ReH(C6H5N2){PPh(OEt)2}4]BPh4 complex was prepared by allowing trihydride ReH3[PPh(OEt)2]4 to react with phenyldiazonium tetrafluoroborate. A reaction path involving the aryldiazene [ReH2(C6H5NNH){PPh(OEt)2}4]+ intermediate was also proposed. 相似文献
36.
Enik? Földes Erik Maloschik Ildikó Kriston Peter Staniek 《Polymer Degradation and Stability》2006,91(3):479-487
The stabilising efficiency of three phosphorous secondary antioxidants of different chemical structures (phosphonite, phosphite and phosphine) was compared in a Phillips type polyethylene. The polymer was processed by six consecutive extrusions in the presence of 700 ppm primary antioxidant and 700 ppm phosphorous compound. The consumption of the secondary antioxidant was followed quantitatively by Fourier transform infrared (FTIR) spectroscopy. The properties of the polymer were characterised by FTIR spectroscopy, colour and rheological measurements, as well as by the determination of its residual thermo-oxidative stability. The results of the experiments proved that the chemical reactions occurring in the first extrusion of the polymer are different from those taking place in the further processing operations. The rate of antioxidant consumption and the chemical reactions of the polymer are strongly affected by the type of the phosphorous secondary antioxidant. The analysis of the results indicated that the three stabilisers must act according to different mechanisms. The investigated phosphine showed the best melt stabilising efficiency, while phosphonite was found to protect the polymer most effectively from discoloration. 相似文献
37.
X-ray crystal structure analyses of (CH3NCO)3 (M) and (ClNCO)3·1/2C2H4Cl2 (C) were carried out at room temperature (MoK, graphite monochromator, =0.71069 Å): 1.M=171.16, monochlinic, P21/c,a=14.848 (1) Å,b=13.400 (2) Å,c=8.149 (1) Å, =100.87 (1)°,V=1 592.3 Å3,Z=8,F(000)=720,d
x
=1.428 Mgm–3, =76m–1,R=6.51%,R
w
=7.01% (964 reflections, 218 parameters). 2.M=281.89, monochlinic, P 21/c,a=9.416 (3) Å,b=5.728 (1) Å,c=18.199 (8) Å, =98.64 (2)°,V=970.4 Å3,Z=4,F(000)=556,d
x
=1.929 Mgm–3, =1.11 mm–1,R=3.96%,R
w
=3.44% (605 reflections, 132 parameters). The ring systems together with the C atoms of the methyl groups in (M) and with the Cl atoms in (C) are planar and have D3h-symmetry. Bond lengths and bond angles are discussed with regard to14N-NQR,35Cl-NQR and vibrational spectroscopic data. 相似文献
38.
A new type phosphite active monomer was synthesized. The resisting oxygen inhibition effect of this monomer and the effects of irradiation dose and concentration of phosphite active monomer on curing were studied. At the same time, curing results were analysed, through gel content and IR spectrum. The excellent resisting oxygen inhibition result of this phosphite active monomer was shown by experiments. EB radiation curing in the air was successfully carried out by the phosphite active monomer. 相似文献
39.
The surface chemical activity of an alumina films grown on Mo(100) by oxidation of aluminum evaporated onto the surface and oxidized using water is examined using Auger, X-ray photoelectron and reflection/absorption infrared spectroscopies. The formation of alumina is confirmed using Auger and X-ray photoelectron spectroscopy from the positions and intensities of the aluminum features and using reflection-absorption infrared spectroscopy from the longitudinal optical modes of the Al–O bonds measured at 935 cm−1. The presence of surface hydroxyls is monitored by forming films using D2O which are evidenced by a feature at 2700 cm−1. Ammonia adsorption on a dehydroxylated surface yields a single peak at 1260 cm−1 due to ammonia adsorbed at a surface Lewis site where the principle symmetry axis of ammonia is oriented perpendicularly to the surface plane. Ammonia also appears to adsorb at Lewis sites on a hydroxylated surface with a slightly different adsorption geometry from that on a dehydroxylated surface. Finally, the chemistry of trimethyl aluminum adsorbed on the planar hydroxylated alumina surface is compared with that found on high-surface-area γ-alumina where the spectra and the chemistry found in both régimes is exactly identical except that the low-frequency methyl bending modes (at 769 and 718 cm−1) are not obscured on the thin film by the intense substrate whereas they are on the high-surface-area support. 相似文献
40.
Gabriele Albertin Stefano Antoniutti Sonia Pizzol 《Journal of organometallic chemistry》2004,689(9):1639-1647
Chloro-complexes [OsCl(N-N)P3]BPh4 (1, 2) [N-N=2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen); P=P(OEt)3 and PPh(OEt)2] were prepared by allowing OsCl4(N-N) to react with zinc dust in the presence of phosphites. Treatment of the chloro-complexes 1, 2 with NaBH4 yielded, in the case of bpy, the hydride [OsH(bpy)P3]BPh4 (4) derivatives. Mono-phosphite [OsCl(bpy)2P]BPh4 (3) complexes were also prepared by reacting the [OsCl2(bpy)2]Cl compound with zinc dust in the presence of phosphite. Protonation reaction of the hydride [OsH(bpy)P3]+ (4) cations with Brønsted acid was studied and led to thermally unstable (above 0 °C) dihydrogen [Os(η2-H2)(bpy)P3]2+ (4*) derivatives. The presence of the H2 ligand is supported by variable-temperature NMR spectra and T1min measurements. Carbonyl [Os(CO)(bpy){P(OEt)3}3](BPh4)2 (5), nitrile [Os(CH3CN)(bpy){P(OEt)3}3](BPh4)2 (6), and hydrazine [Os(bpy)(NH2NH2){P(OEt)3}3](BPh4)2 (7) complexes were prepared by substituting the H2 ligand in the η2-H2 (4*) derivatives. Aryldiazene complex [Os(C6H5NNH)(bpy){P(OEt)3}3](BPh4)2 (8) was also obtained by allowing the hydride [OsH(bpy)P3]BPh4 to react with phenyldiazonium cation. 相似文献