全文获取类型
收费全文 | 349篇 |
免费 | 18篇 |
国内免费 | 8篇 |
专业分类
化学 | 305篇 |
晶体学 | 1篇 |
力学 | 11篇 |
数学 | 25篇 |
物理学 | 33篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 18篇 |
2020年 | 31篇 |
2019年 | 17篇 |
2018年 | 26篇 |
2017年 | 18篇 |
2016年 | 21篇 |
2015年 | 22篇 |
2014年 | 22篇 |
2013年 | 31篇 |
2012年 | 18篇 |
2011年 | 24篇 |
2010年 | 21篇 |
2009年 | 15篇 |
2008年 | 11篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 6篇 |
2003年 | 1篇 |
2002年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1989年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 2篇 |
排序方式: 共有375条查询结果,搜索用时 328 毫秒
1.
JPC – Journal of Planar Chromatography – Modern TLC - A new stability-indicating HPTLC assay has been established for leuprolide acetate. Silica gel 60F254 was used as stationary phase.... 相似文献
2.
Czechoslovak Mathematical Journal - We investigate signed graphs with just 2 or 3 distinct eigenvalues, mostly in the context of vertex-deleted subgraphs, the join of two signed graphs or... 相似文献
3.
A new PVC membrane electrode for Zn2+ ions based on tetra(2-aminophenyl) porphyrin (TAPP) as membrane carrier is prepared. The sensor exhibits a linear stable response over a wide concentration range (5.0×10−5 to 1.0×10−1 M) with a slope of 26.5 mV/decade and a limit of detection 3.0×10−5 M (1.96 ppm). It has a response time of about l0 s and can be used for at least 8 months without any divergence in potential. The propose membrane sensor revealed good selectivities for Zn2+ over a wide variety of other metal ions and can be used in pH range of 3.0–6.0. It was successfully applied to the direct determination of zinc in a pharmaceutical sample and also as an indicator electrode in potentiometric titration of Zn2+ ions. 相似文献
4.
Raissi H Nowroozi A Farzad F Bojd MS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(1-3):343-352
Fourier transform infrared and Fourier transform Raman spectra of Cu(II) bis-acetylacetone have been obtained. The geometry, frequency and intensity of the vibrational bands of this compound and its 1,5-(13)C(2), 3-(13)C, 1,3,5-(13)C(3), 2,4-(13)C(2), (18)O(2) and 2,4-(13)C(2)-(18)O(2) derivatives were obtained by the density functional theory (DFT) with the B3LYP functional and using the 6-31G(*) and 3-21G(*) basis sets. The calculated frequencies are compared with the solid infrared and Raman spectra. All the measured infrared and Raman bands were interpreted in terms of the calculated vibrational modes. The percentage of deviation of the bond lengths and bond angles gives a good picture of the normal modes, and serves as a basis for the assignment of the wavenumbers. Most computed bands are predicted to be at higher wavenumbers than the experimental bands. The calculated geometrical parameters show slight differences compared with the experimental results. These differences can be explained by the different physical state of Cu(II) bis-acetylacetone. The DFT-B3LYP calculations assumed a free molecule in the gas phase. Analysis of the vibrational spectra indicates a strong coupling between the chelated ring modes. 相似文献
5.
6.
Tonya Vitova Radmila Faizova Jorge I. Amaro-Estrada Laurent Maron Tim Pruessmann Thomas Neill Aaron Beck Bianca Schacherl Farzaneh Fadaei Tirani Marinella Mazzanti 《Chemical science》2022,13(37):11038
The stabilization of uranyl(v) (UO21+) by Fe(ii) in natural systems remains an open question in uranium chemistry. Stabilization of UVO21+ by Fe(ii) against disproportionation was also demonstrated in molecular complexes. However, the relation between the Fe(ii) induced stability and the change of the bonding properties have not been elucidated up to date. We demonstrate that U(v) – oaxial bond covalency decreases upon binding to Fe(ii) inducing redirection of electron density from the U(v) – oaxial bond towards the U(v) – equatorial bonds thereby increasing bond covalency. Our results indicate that such increased covalent interaction of U(v) with the equatorial ligands resulting from iron binding lead to higher stability of uranyl(v). For the first time a combination of U M4,5 high energy resolution X-ray absorption near edge structure (HR-XANES) and valence band resonant inelastic X-ray scattering (VB-RIXS) and ab initio multireference CASSCF and DFT based computations were applied to establish the electronic structure of iron-bound uranyl(v).The role of Fe in the increased stability of uranyl(v) is clarified by using state of the art uranium metalorganic chemistry, advanced X-ray spectroscopic approaches and computations. 相似文献
7.
In this study, we present a versatile and easy procedure for modifying a cobalt ferrite nanoparticle step by step. A new nanocatalyst was prepared via CuII immobilized onto CoFe2O4@HT@Imine. The catalyst was fully characterized by Fourier‐transform infrared (FT‐IR), energy‐dispersive X‐ray spectroscopy (EDX), field emission scanning electron microscopy (FE‐SEM), X‐ray diffraction (XRD), and vibrating sample magnetometer (VSM) analyses. The current procedure as a green protocol offers benefits including a simple operational method, an excellent yield of products, mild reaction conditions, minimum chemical wastes, and short reaction times. Without any significant reduction in the catalytic performance, up to five recyclability cycles of the catalyst were obtained. The optimization results suggest that the best condition in the oxidation of benzyl alcohol derivatives is 0.003 g of the CoFe2O4@HT@Imine‐CuII catalyst, TEMPO, at 70°C under solvent‐free condition and air. 相似文献
8.
Aliyari Elnaz Fathi Ali Akbar Alvand Mahrouz Jamshidi Parastoo Shemirani Farzaneh Mozaffari Shahla Neyestani Mahmoud Reza 《Research on Chemical Intermediates》2021,47(5):1905-1918
Research on Chemical Intermediates - This article presents an ultrasound-assisted dispersive magnetic solid-phase extraction method (USA-DMSPE) to preconcentration Cd(II) and Pb(II) simultaneously.... 相似文献
9.
10.
A novel heterogeneous nanocatalyst: 2‐Methoxy‐1‐phenylethanone functionalized MCM‐41 supported Cu(II) complex for C‐S coupling of aryl halides with thiourea
下载免费PDF全文
![点击此处可从《应用有机金属化学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An environmentally friendly copper‐based catalyst supported on 2‐Methoxy‐1‐phenylethanone functionalized MCM‐41 was prepared and characterized by FT‐IR, FE‐SEM, TEM, XRD, EDX, BET and ICP techniques. The catalyst was applied for the C?S cross‐coupling reaction of aryl halides with thiourea. Corresponding products were produced in good yields in aerobic conditions. The catalyst could be recovered and recycled for several times. 相似文献