全文获取类型
收费全文 | 292篇 |
免费 | 4篇 |
专业分类
化学 | 211篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 5篇 |
物理学 | 78篇 |
出版年
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 16篇 |
2011年 | 15篇 |
2010年 | 6篇 |
2009年 | 3篇 |
2008年 | 18篇 |
2007年 | 22篇 |
2006年 | 23篇 |
2005年 | 7篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1971年 | 3篇 |
1969年 | 1篇 |
1965年 | 1篇 |
1918年 | 1篇 |
排序方式: 共有296条查询结果,搜索用时 31 毫秒
101.
Abe K Abe K Abe T Adam I Akimoto H Aston D Baird KG Baltay C Band HR Barklow TL Bauer JM Bellodi G Berger R Blaylock G Bogart JR Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Calcaterra A Cassell R Chou A Cohn HO Coller JA Convery MR Cook V Cowan RF Crawford G Damerell CJ Daoudi M de Groot N de Sangro R Dong DN Doser M Dubois R Erofeeva I Eschenburg V Fahey S Falciai D Fernandez JP Flood K Frey R Hart EL Hasuko K Hertzbach SS Huffer ME Huynh X Iwasaki M Jackson DJ 《Physical review letters》2002,88(15):151801
The parity violation parameters A(b) and A(c) of the Zb(b) and Zc(c) couplings have been measured directly, using the polar angle dependence of the polarized cross sections at the Z(0) pole. Bottom and charmed hadrons were tagged via their semileptonic decays. Both the electron and muon analyses take advantage of new multivariate techniques to increase the analyzing power. Based on the 1993-1998 SLD sample of 550,000 Z(0) decays produced with highly polarized electron beams, we measure A(b) = 0.919+/-0.030(stat)+/-0.024(syst), and A(c) = 0.583+/-0.055(stat)+/-0.055(syst). 相似文献
102.
Sapochak LS Benincasa FE Schofield RS Baker JL Riccio KK Fogarty D Kohlmann H Ferris KF Burrows PE 《Journal of the American Chemical Society》2002,124(21):6119-6125
We present direct evidence for stable oligomers in vacuum-deposited thin films of zinc(II) bis(8-hydroxyquinoline) (Znq(2)). The tetramer [(Znq(2))(4)] is the energetically favored configuration in both the single crystal and the vacuum-deposited thin film. Oligomerization leads to distinct, symmetry-driven differences between the electronic states in Znq(2) and those in the archetypal organic electroluminescent molecule tris(8-hydroxyquinoline) aluminum (Alq(3)). In the case of the Znq(2) tetramer, symmetry leads to an extended network of overlapping pyridyl and phenolato moieties in the solid film. Analysis of the electronic structure of (Znq(2))(4) calculated by ab initio Hartree-Fock (HF) methods reveals a localization and energy shift of high-lying occupied and low-lying unoccupied states on symmetry related ligands located on opposite sides of the supramolecular structure resulting in a dipole moment for (Znq(2))(4) tetramer close to zero. The optimal pi-overlap pathways, altered charge distributions, and extended electronic states of tetrameric Znq(2) may be expected to enable low operating voltage organic light-emitting devices (OLEDs) based on Znq(2). We present preliminary evidence that the operating voltage of (Znq(2))(4)-based OLEDs is indeed lower than that of identical devices made with Alq(3). Strategic substitution of 8-hydroxyquinoline ligands and control of the structural symmetry of the corresponding metal chelates may offer a route to high efficiency and low operating voltage small molecule OLEDs. 相似文献
103.
104.
Synthesis,characterization and assessment of the cytotoxic activity of Cu(II), Fe(III) and Mn(III) complexes of camphoric acid‐derived salen ligands
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)
Dina Murtinho Zênis N. da Rocha Ana Salomé Pires Roberto P. Jiménez Ana Margarida Abrantes Mafalda Laranjo Ana Catarina Mamede João Eduardo Casalta‐Lopes Maria Filomena Botelho Alberto A. C. C. Pais Sandra C. C. Nunes Hugh D. Burrows Telma Costa M. Elisa Silva Serra 《应用有机金属化学》2015,29(7):425-432
Novel Cu(II), Fe(III) and Mn(III) salen‐type metal complexes from (1R,3S)‐N,N′‐bis[salicylidene]‐1,3‐diamino‐1,2,2‐trimethylcyclopentane were synthesized and screened for their in vitro cytotoxic activity against three human cancer cell lines: melanoma, colorectal and breast. In vitro experiments carried out with the three metal complexes show that the copper complex exhibits the highest cytotoxic activity towards all cell lines studied, presenting IC50 values of 3.32–6.71 μM. A significant improvement in the anti‐proliferative effect, by 20‐fold, is observed with this complex when compared with conventional chemotherapy. The relationship between structure, redox characteristics and biological activity in human cancer cell lines was evaluated for the most efficient Cu(II) complex and associated with theoretical calculations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
105.
Shear horizontal (SH) ultrasound guided waves are being used in an increasing number of non-destructive testing (NDT) applications. One advantage SH waves have over some wave types, is their ability to propagate around curved surfaces with little energy loss; to understand the geometries around which they could propagate, the wave reflection must be quantified. A 0.83 mm thick aluminium sheet was placed in a bending machine, and a shallow bend was introduced. Periodically-poled magnet (PPM) electromagnetic acoustic transducers (EMATs), for emission and reception of SH waves, were placed on the same side of the bend, so that reflected waves were received. Additional bending of the sheet demonstrated a clear relationship between bend angles and the reflected signal. Models suggest that the reflection is a linear superposition of the reflections from each bend segment, such that sharp turns lead to a larger peak-to-peak amplitude, in part due to increased phase coherence. 相似文献
106.
Jessica E. Sharpe Nuno Bimbo Valeska P. Ting Andrew D. Burrows Dongmei Jiang Timothy J. Mays 《Adsorption》2013,19(2-4):643-652
Experimental excess isotherms for the adsorption of gases in porous solids may be represented by mathematical models that incorporate the total amount of gas within a pore, a quantity which cannot easily be found experimentally but which is important for calculations for many applications, including adsorptive storage. A model that is currently used for hydrogen adsorption in porous solids has been improved to include a more realistic density profile of the gas within the pore, and allows calculation of the total amount of adsorbent. A comparison has been made between different Type I isotherm equations embedded in the model, by examining the quality of the fits to hydrogen isotherms for six different nanoporous materials. A new Type I isotherm equation which has not previously been reported in the literature, the Unilan-b equation, has been derived and has also been included in this comparison study. These results indicate that while some Type I isotherm equations fit certain types of materials better than others, the T?th equation produces the best overall quality of fit and also provides realistic parameter values when used to analyse hydrogen sorption data for a model carbon adsorbent. 相似文献
107.
P. N. Burrows 《Zeitschrift fur Physik C Particles and Fields》1988,41(3):375-384
Results on event and single particle characteristics are presented for the three most successful perturbative QCD+fragmentation models in the c.m. energy range 12.0≦W≦200 GeV. The models were optimised to describe the properties of the large sample of hadronic events obtained by TASSO atW=35 GeV. The energy evolution of the observables across the range spanned by the PETRA and PEP data, 12.0≦〈W〉≦41.5 GeV, is reasonably well described by all the models. However, for some quantities the predictions of the different models diverge at higher energies; distributions of observables are shown at c.m. energies of 93 and 200 GeV, where data are expected from thee + e ? colliders currently under construction. The ability to describe simultaneously, with the same parameter values, hadronic event features both at PETRA/PEP and LEP/SLC energies will provide a severe test of the models. The effects of top quark production on the event properties are illustrated for a top mass of 60 GeV/c2. Predictions are given for the rates of multijet events up toW=200 GeV, where ≧4-jet events dominate the cross section and will form a background to events containing heavy states which decay into hadron jets. 相似文献
108.
The reaction between N(alpha)-acetyllysine methyl ester (Lys) and 2'-deoxyguanosine (dGuo) was used to study structural aspects of DNA-protein cross-link (DPC) formation. The precise structure of DPCs depended on the nature of the oxidant and cross-linking reactions in which a series of different oxidation conditions generated a distribution of adducts, principally spirodiiminodihydantoins with lysine appended at the purine position of C5 (5-Lys-Sp), C8 (8-Lys-Sp), or both C5 and C8 (5,8-diLys-Sp). Singlet oxygen oxidation of dGuo produced 5-Lys-Sp exclusively when Rose Bengal or methylene blue was used to photochemically generate (1)O2 in the presence of Lys, whereas riboflavin or benzophenone-mediated photochemistry generated lysine radicals and led to C8 adduct formation, yielding 8-Lys-Sp and 5,8-diLys-Sp. Notably, the yield of dGuo modifications from riboflavin photooxidation increased dramatically in the presence of lysine. Oxidation of deoxyguanosine/lysine mixtures with Na2IrCl6 or sulfate radicals produced both 5-Lys-Sp and 8-Lys-Sp. The same adducts were formed in single and double-stranded oligodeoxynucleotides, and these could be analyzed after nuclease digestion. Adduct formation in duplex DNA was somewhat dependent on the accessibility of lysine to C5 vs C8 of the purine. No adduct formation was detected between lysine and the other nucleobases T, C, or A. Overall, the precise location of adduct formation at C5 vs C8 of guanine appears to be diagnostic of the oxidation pathway. 相似文献
109.
Jones C Taylor SH Burrows A Crudace MJ Kiely CJ Hutchings GJ 《Chemical communications (Cambridge, England)》2008,(14):1707-1709
Low levels of cobalt doping (1 wt%) of copper manganese oxide enhances its activity for carbon monoxide oxidation under ambient conditions and the doped catalyst can display higher activity than current commercial catalysts. 相似文献
110.
Inside Cover: An Iodine‐Vapor‐Induced Cyclization in a Crystalline Molecular Flask (Angew. Chem. Int. Ed. 20/2016)
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)