全文获取类型
收费全文 | 235篇 |
免费 | 7篇 |
国内免费 | 6篇 |
专业分类
化学 | 149篇 |
晶体学 | 1篇 |
力学 | 11篇 |
数学 | 40篇 |
物理学 | 47篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 14篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 20篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 29篇 |
2012年 | 17篇 |
2011年 | 24篇 |
2010年 | 17篇 |
2009年 | 17篇 |
2008年 | 11篇 |
2007年 | 12篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有248条查询结果,搜索用时 109 毫秒
71.
The ortho-metallated complexes [Pd2{κ2(C,C)-C6H4(PPh2CHC(O)C6H5R}2(μ-Cl)2] (R = Ph (1a), NO2 (1b), Br (1c)) were prepared by refluxing equimolar mixtures of Ph3PCHC(O)C6H5R, (R = Ph, NO2, Br) and Pd(OAc)2 in MeOH, followed by an excess of NaCl. The dinuclear complexes (1a-1c) react with silver trifluoromethylsulfonate and bidentate ligands [L = bipy (2,2′-bipyridine), phen (phenanthroline), dppe (bis(diphenylphosphino)ethane), dppp (bis(diphenylphosphino)propane)] giving the mononuclear stabilized orthopalladated complexes in endo position [Pd{κ2(C,C)-C6H4(PPh2CHC(O)R}L](OTf) [R = Ph, L = phen (2a), bipy (3a), dppe (4a), dppp (5a); R = NO2, L = phen (2b), bipy (3b), dppe (4b), dppp (5b); R = Br, L = phen (2c), bipy (3c), dppe (4c), dppp (5c); OTf = trifluoromethylsulfonate anion]. Orthometalation and ylidic C-coordination are demonstrated by an X-ray diffraction study of 2c and 3c. In the structures, the palladium atom shows a slightly distorted square-planar coordination geometry. 相似文献
72.
73.
Benzyl chloride was treated with (Me3Si)3CLi to give (Me3Si)3CCH2Ph (1). A new styrene derivative, (Me3Si)3CCH2C6H4(CHCH2-p) (2), was synthesized by reaction of p-vinylbenzyl chloride with (Me3Si)3CLi in the presence of CuCl. Addition and oxidation reactions on 2 gave a series of new compounds (Me3Si)3CCH2C6H4X-p (X = CH2CH3, CHBrCH2Br, CHClCH2I, CHBrCH2I, cyclo-C3H3Cl2, CHOHCH2OH, COOH, CH2OH). 相似文献
74.
Colin Eaborn Duncan A.R. Happer Peter B. Hitchcock Steven P. Hopper Kazem D. Safa Stephen S. Washburne David R.M. Walton 《Journal of organometallic chemistry》1980,186(3):309-323
The compound (Me3Si)3CSiPh2F loses Me3SiF under reflux or on passage through a tube at 450°C to give three products, A, B, and C, in approximately 20/20/60 ratio. Products A and B, which are solids, were shown by X-ray crystallographic analysis to be the diastereoisomeric forms of 1-dimethylsila-2-trimethylsilyl-3-[(methyl)(phenyl)sila]indane. From its mass and 1H NMR spectra, C (a liquid) was tentatively identified as 1,3-bis(dimethylsila)-2-[(dimethyl)(phenyl)silyl]indane. All three products are isomers of the sila-olefin (Me3Si)2CSiPh2, and it is suggested that the latter is first formed by loss of Me3SiF from (MeSi)3CSiPh2F, and the equilibrium (Me3Si)2CSiPh2 ? (Me3Si)(Ph2MeSi)CSiMe2 ? (Me3Si)(PhMe2Si)CSiMePh ? (Me2PhSi)2CSiMe2 is then rapidly established; internal cyclizations involving addition of aryl CH bonds across SiC bonds then occur to give the observed products. Consistent with this is the observation that a mixture of silicon alkoxides, thought to be (Me3Si)2CHSiPh2OMe and its isomers (which would be formed by addition of methanol across the SiC bonds of the four sila-olefins) is produced when methanol is passed through the hot tube with the (Me3Si)3CSiPh2F.Full structural details are given for compounds A and B. Some features of interest are: (a) the conformation of the 5-membered ring is different in the two diastereoisomers; (b) the exocyclic SiCSiMe3 bond angles, of ca. 120° are unusually large; and (c) there is a little distortion of the fused benzene ring, which is attributed to the effect of silicon substituents on the hybridization of carbon atoms to which they are attached. 相似文献
75.
76.
77.
78.
Four new monomeric Pd (II) complexes with formulas [Pd(C,N)‐(2′‐NH2C6H4)C6H4 (N3)(L)] ( A ), ( B ) and [Pd(C,N)‐C6H4CH2NH(C4H9)(N3)(L)] ( C ), ( D ), [L = isonicotinamide for ( A ) and ( C ), L = 4‐N,N‐dimethylaminopyridine for ( B ) and ( D )] have been synthesized using four initial dimers [Pd2{(C,N)‐(2′‐NH2C6H4)C6H4}2(μ‐OAc)2] ( 1 ), [Pd2{(C,N)‐ (2′‐NH2C6H4)C6H4}2(μ‐N3)2] ( 3 ) for A and C , and [Pd2{(C,N)‐C6H4CH2NH(C4H9)}2(μ‐OAc)2] ( 2 ) and [Pd2{(C,N)‐C6H4CH2NH(C4H9)}2(μ‐N3)2] ( 4 ) for B and D . Then synthesized complexes have been characterized by Fourier transform‐infrared, NMR spectroscopy and thermal gravimetric‐differential thermal analysis. Furthermore, UV–Vis spectroscopy, fluorescence spectroscopy, circular dichroism (CD) and helix melting temperature measurements have been employed to study the binding interaction of them with calf thymus‐deoxyribonucleic acid (DNA). The results reveal that all synthesized complexes can interact with DNA via groove‐binding mode. Bovine serum albumin (BSA)‐binding studies have been carried out using UV–Vis spectroscopy, emission titration and CD. However, competitive binding studies using warfarin, ibuprofen and digoxin on site markers demonstrated that the complexes bind to different sites on BSA. The results also indicated that the binding site was mainly located within site‐III for complex A , and site‐I for complexes B , C and D of BSA. In addition, molecular docking studies have been executed to determine the binding site of the DNA and BSA with complexes. Eventually, in vitro cytotoxicity of synthesized palladium complexes and cisplatin were carried out against human promyelocytic leukemia cancer (Hela) and breast cancer (MCF‐7) cell lines. Pursuant to the IC50 values, the cytotoxicity of complexes against MCF‐7 was more than Hela. 相似文献
79.
80.
Hossein Mahmoodi Darian Vahid Esfahanian Kazem Hejranfar 《Journal of computational physics》2011,230(3):494-514
A new shock-detecting sensor for properly switching between a second-order and a higher-order filter is developed and assessed. The sensor is designed based on an order analysis. The nonlinear filter with the proposed sensor ensures damping of the high-frequency waves in smooth regions and at the same time removes the Gibbs oscillations around the discontinuities when using high-order compact finite difference schemes. In addition, a suitable scaling is proposed to have dissipation proportional to the shock strength and also to minimize the effects of the second-order filter on the very small scales. Several numerical experiments are carried out and the accuracy of the nonlinear filter with the proposed sensor is examined. In addition, some comparisons with other filters and sensors are made. 相似文献