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111.
Eric Block Marc Birringer Chunhong He 《Angewandte Chemie (International ed. in English)》1999,38(11):1604-1607
Ring opening of titanacyclopentadienes 1 with (SCN)2 or (SeCN)2 followed by bis(thiocyanate) or bis(selenocyanate) cyclization affords 1,2-dithiin ( 2 a ) or 1,2-diselenin ( 2 b ), respectively. Compound 1 gives 2 a directly on reaction with S2Cl2. Unsubstituted 1,2-diselenin is prepared by reaction of PhCH2SeNa with 1,4-bis(trimethylsilyl)-1,3-butadiyne followed by reductive cleavage of the benzyl group and oxidation. The unsubstituted 2-selenathiin is prepared in an analogous manner, but from a mixture of PhCH2SeNa and PhCH2SNa. 相似文献
112.
农药光解平均波长量子产率的测定 总被引:6,自引:0,他引:6
本文报道一种以高压汞灯复合光为光源测定农药平均波长量子产率的方法。该方法的光最计为草酸铁钾,通过光量计测得光源的照射强度。以气相色谱分析农药降解的残余浓度求得反应速率常数,用紫外分光光度计测定农药在确定波长下的摩尔吸光系数,并与该波长光强相乘进行积分,计算出十二种农药的平均波长Φ。本法所得结果更接近于自然光下的结果,更适合应用于实际环境中。 相似文献
113.
A slow and clean fluorine atom beam source is one of the essential components for the low-collision energy scattering experiment involving fluorine atom. In this work, we describe a simple but effective photolysis fluorine atom beam source based on ultraviolet laser photolysis, the performance of which was demonstrated by high-resolution time-of-flight spectra from the reactive scattering of F+HD. This beam source paved the way for studies of low energy collisions with fluorine atoms. 相似文献
114.
Nadezhda A. Bokach Matti Haukka Pipsa Hirva Vadim Yu. Kukushkin 《Journal of organometallic chemistry》2006,691(11):2368-2377
Photochemical exchange of carbonyls was used to produce new ruthenium dialkylcyanamide and nitrile compounds [RuCl2(bpy)(CO)(NCNMe2)] (2), [RuCl2(bpy)(CO)(NCNEt2)] (3), and [RuCl2(bpy)(CO)(NCEt)] (4) from trans(Cl)-[RuCl2(bpy)(CO)2] (1). The reaction energetics, steric effects and electronic effects induced by the dialkylcyanamide and nitrile ligands were studied using computational DFT methods and cyclic voltammetry. In all cases the photochemical exchange reaction favors rearrangement of the ligands and formation of the trans(Cl,L)-[RuCl2(bpy)(CO)L] (L = NCNMe2, NCNEt2 or NCEt) isomer as the main products. The oxidation potential of the complexes decreases with the increase of the HOMO energy and of net electron-donor character of the ligands, the dialkylcyanamides (whose electrochemical Lever EL ligand parameter has been estimated) behaving as stronger net electron donors than propiononitrile or CO. The electronic effect of the dialkylcyanamide and nitrile ligands is also reflected into the HOMO-LUMO energy difference, which is slightly reduced compared to the original dicarbonyl compound 1. The computational results show that the geometry of the isomer plays also an important role in the determination of orbital energies. 相似文献
115.
Dilek Ay?e Bo?a 《Journal of organometallic chemistry》2006,691(15):3293-3297
Photolysis of hexacarbonyltungsten(0) in the presence of acryloylferrocene in n-hexane solution at 10 °C yields pentacarbonyl(η2-acryloylferrocene)tungsten(0) (1) as the only photo-substitution product, different from the general reaction pattern observed for the Group 6 metal carbonyls with other olefins. W(CO)5(η2-acryloylferrocene) (1) decomposes in solution to the parent hexacarbonyltungsten(0) and free acryloylferrocene. Trimethylphosphite was introduced as ligand into the molecule to increase the stability. The photolysis of pentacarbonyl(trimethylphosphite)tungsten(0) in the presence of acryloylferrocene in n-hexane solution at 10 °C yields only cis-W(CO)4[P(OCH3)3](η2-acryloylferrocene) (2) as the monosubstitution product. Both η2-acryloylferrocene complexes (1 and 2) could be isolated and characterized by MS, IR and NMR spectroscopy. The trimethylphosphite complex (2) is found to be even less stable than W(CO)5(η2-acryloylferrocene) (1). 相似文献
116.
117.
Photolysis reaction of dibenzo[a,d]cycloheptene dimer 3 provides three dibenzo[a,d]cycloheptyl dimers 4 , 5 and 6 under different irradiation conditions via the intramolecular degradative cyclodimerization. A tetracyclic benzo[4,5]cyclohepta[1,2,3‐de]naphthalene core is also synthesized. 相似文献
118.
Photochemistry of the title compounds in various solvents was studied using a broad band of light centered at 350 nm. C-4 spiroketal cyclohexenone 4 (1.0 M) afforded dimers and 12b with the predominance of the former in polar solvent and the latter in nonpolar solvent. When the concentration was reduced to, 4 underwent solvent addition in nonpolar solvent and ring-contraction in polar solvents. 4,4-Dimethoxycyclohexenones 5a–d in TFE exhibited a different photochemical behavior. The 5-vinyl-substituted enone afforded the bridged-bicyclic ketone 16. Cyclohexenone 5b with methyl moieties at C-2 and C-3 underwent aromatization whereas cyclohexenones with butyl substituent at C-5 and 5d with silylated alcohol at C-2 underwent solvent exchange. In γ-hydroxylated cyclohexenones 6a–c ring-contraction and solvent exchange were observed. Photochemistry of the title compounds from the mechanistic viewpoint is also described. 相似文献
119.
‘Caging’ and ‘uncaging’ bioactive substrates are key techniques in studying a wide variety of biological processes. In the present study, two-types of novel caged glutamates with a two-photon absorption (TPA) core, that is, π-extended coumarin, were synthesized and their photochemical release of glutamate was analyzed. The high yields of glutamate (>92%) were observed in the photolysis of compounds 1 and 10, respectively. 相似文献
120.
Photolysis of hexacarbonylchromium(0) in the presence of 2,6-diaminopyridine in toluene solution at 10 °C yields pentacarbonyl(2,6-diaminopyridine)chromium(0), which could be isolated from solution as plate-like crystals and fully characterized by using the single crystal X-ray diffractometry and MS, IR, 1H and 13C NMR spectroscopy. The complex was found to have the 2,6-diaminopyridine ligand bonded to the chromium atom through one of the NH2 groups. A single crystal X-ray structure of the complex reveals that the coordination sphere around the chromium atom is a slightly distorted octahedron, involving five carbonyls and one 2,6-diaminopyridine ligand. Because of the steric requirement of 2,6-diaminopyridine the four equatorial carbonyl groups are bended away from the N-donor ligand. The pyridine plane makes an angle of 112.9(3)° with the OC-Cr-N bond axis. The Cr-C distances have values between 1.833(7) and 1.935(7) Å. The Cr-N distance is 2.236(5) Å. 相似文献