全文获取类型
收费全文 | 269篇 |
免费 | 16篇 |
国内免费 | 38篇 |
专业分类
化学 | 285篇 |
晶体学 | 1篇 |
力学 | 4篇 |
综合类 | 1篇 |
数学 | 20篇 |
物理学 | 12篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 13篇 |
2020年 | 15篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 10篇 |
2013年 | 35篇 |
2012年 | 22篇 |
2011年 | 14篇 |
2010年 | 6篇 |
2009年 | 11篇 |
2008年 | 13篇 |
2007年 | 8篇 |
2006年 | 16篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 23篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 8篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有323条查询结果,搜索用时 15 毫秒
1.
赵志伟 《光谱学与光谱分析》2002,22(6):895-897
在化学发光分析中,常常要用到碱性条件下鲁米诺与过氧化氢的反应系统,通过催化剂辣根过氧化物酶使反应顺利进行。如果再加入适当的增强剂,则灵敏度提高且发光时间延长,可改善测定的重现性。实验证明,对位酚类衍生物,如:对叔丁基苯酚,对甲苯酚的发光增强作用明显,其发光效率可上升几十倍,发光时间也获得有效延长。 相似文献
2.
The use of reagent concentration has resulted in increased rates for all stages of the REM resin synthesis of tertiary amines. These increases in rate translate into faster reaction times, higher yields and lower reagent consumption. Of the methods examined, the most successful was the use of perfluorous solvents, either alone or with a small amount of organic co-solvent. 相似文献
3.
Total syntheses of the peptide enamide natural products terpeptin and aspergillamides A and B are reported. An oxidative decarboxylation-elimination protocol is employed to construct the indolic enamide moiety. Unambiguous stereochemical assignment of (−)-terpeptin is accomplished by synthesis of all possible stereochemical analogues. Select compounds have been evaluated in cell cycle inhibitor assays which show that the natural amino acid configuration of terpeptin has the most potent inhibitory activity. 相似文献
4.
Tertiary N-ethylamines were converted into amide derivatives by reactions with sulfur monochloride and DABCO at 0 °C. Depending on the
nature of the substituents in the amine, the reaction can be accompanied by unexpected transformations.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1135–1140, June, 2007. 相似文献
5.
Roser Cervellera Xavier Ramis Josep Maria Salla Ana Mantecn Angels Serra 《Journal of polymer science. Part A, Polymer chemistry》2006,44(9):2873-2882
N,N‐Dimethylaminopyridine (DMAP) was used as initiator to cure mixtures of diglycidylether of bisphenol A (DGEBA) and 1,3‐dioxan‐2‐one (TMC) or 5,5‐dimethyl‐1,3‐dioxan‐2‐one (DMTMC). The curing was studied by differential scanning calorimetry (DSC) and Fourier transform infrared in the attenuated‐total‐reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and to quantify the evolution of the groups involved in the curing. We observed the formation of five‐membered cyclic carbonates and anionic carbonate groups that remain unreacted at the chain ends. The formation of these groups was explained by the attack of the anionic propagation species on the methylene carbon of the carbonate group, which leads to an alkyl‐oxygen rupture. By performing the cure in the thermobalance we could evaluate the loss of CO2 produced in the samples containing carbonates. The kinetics were studied by DSC and analyzed with isoconversional procedures. The addition of carbonates slows down the curing rate. Thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) experiments were used to evaluate the properties of the materials obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2873–2882, 2006 相似文献
6.
I. P. Romanova S. G. Fattakhov A. A. Nafikova I. I. Vandyukova R. R. Shagidullin N. M. Azancheev V. S. Reznik O. G. Sinyáshin 《Russian Chemical Bulletin》1998,47(9):1812-1819
The reactions of phosphine derivatives of diallyl isocyanurates with palladium(ii) dichloride lead to the formation of complexes, whose structure, composition, and stability depend on the length of the methylene
chain between the isocyanurate and diphenylphosphine fragments in the ligand. 1,3-Diallyl-5-[5′-(diphenylphosphino)pentyl
and 10′-(diphenyl-phosphino)decyl] isocyanurates with PdCl2 form monomeric L2PdCl2
trans-complexes in which P atoms of the ligands participate in coordination with the metal. 1,3-Diallyl-5-[2′-(diphenylphosphino)ethyl]
isocyanurate with PdCl2 forms a dimeric (LPdCl2)2 complex, which decomposes in a solution to the monomer including solvent molecule into the coordination sphere of the metal.
The reactions of 1,3-diallyl-5-[4′-(diphenylphosphino)butyl] isocyanurate and 1,3-diallyl-5-[6′-(diphenylphosphino)hexyl]
isocyanurate with PdCl2 give monomeric chelate LPdCl2 complexes in which one of the allyl groups of the isocyanurate cycle participates in coordination with the central ion along
with the phosphorus atom.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1859–1865, September, 1998. 相似文献
7.
Khafizova L. O. Ibragimov A. G. Yalalova D. F. Borisova A. L. Khalilov L. M. Dzhemilev U. M. 《Russian Chemical Bulletin》2003,52(9):2012-2016
A method for the synthesis of secondary and tertiary alcohols was developed. The method is based on cycloalumination of olefins with trialkylalanes in the presence of Zr-containing catalysts followed by the CuCl-catalyzed in situ reaction of the corresponding aluminacyclopentanes with aldehydes or ketones. 相似文献
8.
A method has been developed for highly sensitive determination of haloperidol in human serum involving a simple extraction procedure followed by gas chromatographic separation. Target components were separated from the extracting solvents with a Van den Berg type solventless sample injector before introduction Into a DB-1 capillary separation column. A surface ionization detector (SID), which has highly selective sensitivity for Substituted amines, was employed for quantitation using bromperidol as an internal standard. Chloroform proved to be the best extracting solvent, yielding a quantitative detection limit of 5 ng/ml (S/N = 2). Comparison of the response to target compounds obtained by the SID, FTD (flame thermionic detector), and FID (flame ionization detector) showed the SID to be superior. 相似文献
9.
Boris A TrofimovSvetlana F Malysheva Boris G SukhovNatal'ya A Belogorlova Elena Yu SchmidtLyubov N Sobenina Vladimir A KuimovNina K Gusarova 《Tetrahedron letters》2003,44(13):2629-2632
Secondary phosphines 1-3 react readily with N-vinylpyrroles 4 and 5 under radical initiation to give regiospecifically anti-Markovnikov adducts, diorganyl-2-(1-pyrrolyl)ethylphosphines 6a-d, highly reactive building blocks for organic synthesis, in 88-91% yields. 相似文献
10.
Ruthenium halides (Cl and Br) react with monotertiary arsines-Ph2RAs (R=Me, Et, Pr
n
) in methoxyethanol, in the presence of aq. formaldehyde to give monocarbonyl complexes of ruthenium(II) of the type RuX2(CO) (Ph2RAs)3. Carbonylation of an ethanolic solution containing ruthenium trichloride and the arsine at room temperature yieldtrans dicarbonyl compounds of the formula RuCl2(CO)2 (Ph2RAs)2. The osmium monocarbonyls OsX2(CO) (Ph2RAs)3 (X=Cl, Br; R=Me, Et) react with NaBH4 in methanol to yield complexes of the composition OsHX(CO) (Ph2RAs)3. The ruthenium analogues RuHCl(CO) (Ph2RAs)3 have also been made. Structures have been assigned to all these compounds on the basis of IR and NMR spectral results. 相似文献