全文获取类型
收费全文 | 145篇 |
免费 | 4篇 |
国内免费 | 25篇 |
专业分类
化学 | 143篇 |
晶体学 | 1篇 |
力学 | 4篇 |
物理学 | 26篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 8篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 7篇 |
2012年 | 11篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 10篇 |
2008年 | 17篇 |
2007年 | 20篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1990年 | 5篇 |
1985年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有174条查询结果,搜索用时 15 毫秒
21.
Tao Zhao Yuan Ren Guangyou Jia Yuye Zhao Yuchi Fan Jianping Yang Xin Zhang Wan Jiang Lianjun Wang Wei Luo 《中国化学快报》2019,30(12):2032-2038
Nanocomposites constructed by combining mesoporous metal oxides and graphene have received tremendous attention in wide fields of catalysis,energy storage and conversion,gas sensing and so on.Herein,we present a facile interface-induced co-assembly process to synthesize the mesoporous W03@graphene aerogel nanocomposites(denoted as mW03@GA),in which graphene aerogel(GA) was used as a macroporous substrate,mesoporous W03 was uniformly coated on both sides of graphene sheets through a solvent evaporation-induced self-assembly(EISA) strategy using diblock copolymer poly(ethylene oxide)-b-polystyrene(PEO-b-PS) as a template.The resultant mW03@GA nanocomposites possess well-interconnected macroporous graphene networks covered by mesoporous W03 layer with a uniform pore size of 19 nm,high surface area of 167 m~2/g and large pore volume of 0.26 cm~3/g.The gas sensing performance of mW03@GA nanocomposites toward acetone and other gases was studied,showing a high selectivity and great response to acetone at low temperature of 150℃,which could be developed as a promising candidate as novel sensors for VOCs detection. 相似文献
22.
The separation of the toxicologically important aldehyde acrolein from other carbonyl compounds by high performance liquid chromatography after derivatization to 2,4-dinitrophenylhydrazones is critically discussed on the basis of a selection of published methods. A method is proposed whereby the compounds acrolein, acetone, and propanal may be reproducibly separated to baseline by a reversed phase HPLC procedure employing a ternary mixture of methanol, water, and acetonitrile as mobile phase. 相似文献
23.
建立了测定丙酮中痕量阴离子的离子色谱分析方法.采用的是高效液相柱切换进样,其中泵的流速为0.5 mL/min,使低浓度的丙酮水溶液在保护柱上富集,通过离子色谱抑制电导法分离和检测丙酮样品中痕量的阴离子.色谱条件为:以IonPacAG9-HC(50 mm×2 mm)型柱串联在定量环中进行富集,IonPacAG9-HC(50 mm×2 mm)保护柱,IonPac AS9-HC(250 mm×2 mm)阴离子分离柱进行分离,流动相为9 mmol/L Na2CO3-1.667 mol/L NaHCO3,所得回收率在96.21%~101.56%之间,线性良好,且具有较好的重现性和较低的检出限. 相似文献
24.
Sumit Saha 《Tetrahedron letters》2008,49(41):5928-5930
A mild and efficient method for the preparation of acetonides from epoxides catalyzed by iron(III) chlorides has been developed. 相似文献
25.
Issa Yavari Maryam Sabbaghan Zinatossadat Hossaini Majid Ghazanfarpour‐Darjani 《Helvetica chimica acta》2008,91(6):1144-1147
Triphenyl phosphite reacts smoothly with dialkyl acetylenedicarboxylates and hexachloroacetone to produce alkyl 2‐(dichloromethylene)‐2,5‐dihydro‐5‐oxo‐4‐(trichloromethyl)furan‐3‐carboxylates in good yields. 相似文献
26.
The role of the ocean in the cycling of oxygenated volatile organic compounds (OVOCs) remains largely unanswered due to a paucity of datasets. We describe the method development of a membrane inlet-proton transfer reaction/mass spectrometer (MI-PTR/MS) as an efficient method of analysing methanol, acetaldehyde and acetone in seawater. Validation of the technique with water standards shows that the optimised responses are linear and reproducible. Limits of detection are 27 nM for methanol, 0.7 nM for acetaldehyde and 0.3 nM for acetone. Acetone and acetaldehyde concentrations generated by MI-PTR/MS are compared to a second, independent method based on purge and trap-gas chromatography/flame ionisation detection (P&T-GC/FID) and show excellent agreement. Chromatographic separation of isomeric species acetone and propanal permits correction to mass 59 signal generated by the PTR/MS and overcomes a known uncertainty in reporting acetone concentrations via mass spectrometry. A third bioassay technique using radiolabelled acetone further supported the result generated by this method. We present the development and optimisation of the MI-PTR/MS technique as a reliable and convenient tool for analysing seawater samples for these trace gases. We compare this method with other analytical techniques and discuss its potential use in improving the current understanding of the cycling of oceanic OVOCs. 相似文献
27.
Ni,Pd/Al2O3对丙酮加氢一步合成甲基异丁基酮性能比较 总被引:7,自引:0,他引:7
研究了Al2O3负载Ni、Pd催化剂上丙酮加氢一步合成甲基异丁基酮的反应活性。考察了不同Ni含量和不同Pd含量对活性的影响。结果表明,在载体Al2O3中加入不同含量的SiO2后,会改善载体的性能,Ni/Al2O3催化剂中添加稀土元素La或Ce后可改善催化剂的稳定性。 相似文献
28.
Sitaram Pal Sukumar Ghosh Bimal K. Banik Shaikh Khairul Alam Usha Ranjan Ghatak 《合成通讯》2013,43(14):2203-2216
The bridged-ethers, (±)-2-methoxy-9a-carbamorphinan (1b) and (±)-2-methoxy-9a-carba-14α-morphinan(2b) have been synthesized. The acid-catalyzed cyclizations of 1-m-methoxy benzyloctalone 3b and 1-m-methoxybenzyloctalins 4b proceed with high regio-and stereoselectivities leading mostly to the bridged-ketone 14 and ether 1b respectively, along with o-methoxy-tetracyclic ketone 15 and the ether 17, in addition to other minor products. 相似文献
29.
Andrey Yu. Manakov Andrey G. Ogienko Vladislav Yu. Komarov Aleksei I. Ancharov Michail A. Sheromov 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(3-4):317-320
X-ray diffraction study of quenched sample of acetone clathrate hydrate synthesized at 0.8 GPa was carried out. It was shown
that the host frameworks of the hydrate comprise uniform cavities which are similar to that of recently characterized structure
of high-pressure tetrahydrofurane hydrate. The unique peculiarity of investigated hydrate is decrease in the crystallographic
symmetry of the hydrate arising from ordering in guest subsystem. 相似文献
30.