全文获取类型
收费全文 | 167篇 |
免费 | 5篇 |
专业分类
化学 | 68篇 |
数学 | 15篇 |
物理学 | 89篇 |
出版年
2020年 | 3篇 |
2018年 | 2篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2013年 | 6篇 |
2012年 | 2篇 |
2011年 | 7篇 |
2009年 | 1篇 |
2008年 | 8篇 |
2007年 | 4篇 |
2006年 | 6篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1959年 | 1篇 |
1888年 | 1篇 |
1878年 | 2篇 |
1872年 | 1篇 |
1868年 | 1篇 |
1864年 | 1篇 |
1862年 | 1篇 |
排序方式: 共有172条查询结果,搜索用时 31 毫秒
61.
K. Vajravelu J.R. Cannon J. Leto R. Semmoum S. Nathan M. Draper D. Hammock 《Journal of Mathematical Analysis and Applications》2003,277(2):609-623
Solutions for a class of coupled nonlinear differential equations, arising in free convection flow at a vertical flat plate embedded in a saturated porous medium at high Reynolds numbers in the presence of heat sources (or sinks) and with nonlinear density temperature variation, are obtained. Further, using the Schauder theory and numerical results, existence and analyticity results are established. 相似文献
62.
63.
Norman R. Draper Berthold Heiligers Friedrich Pukelsheim 《Annals of the Institute of Statistical Mathematics》1996,48(2):395-402
We obtain results for choosing optimal third order rotatable designs for the fitting of a third order polynomial response surface model, for m3 factors. By representing the surface in terms of Kronecker algebra, it can be established that the two parameter family of boundary nucleus designs forms a complete class, under the Loewner matrix ordering. In this paper, we first narrow the class further to a smaller complete class, under the componentwise eigenvalue ordering. We then calculate specific optimal designs under Kiefer's % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqOXdy2aaS% baaSqaaiaadchaaeqaaaaa!38C6!\[\phi _p \] (which include the often used E-, A-, and D-criteria). The E-optimal design attains a particularly simple, explicit form.N. R. D. is grateful for the partial support from the Scientific and Environmental Affairs Division of the North Atlantic Treaty Organization, and from the National Security Agency through Grant MDA904-95-H-1020. 相似文献
64.
Synthetic mixtures of aliphatic and aromatic ethers, satmated fatty acids, and substituted benzenes and naphthalenes were separated by elution through columns of ion-exchange resins with aqueous solutions of acetic acid as eluent An attempt was made to use a resin of low capacity for the separation of such mixtures, and the results of this attempt are used to help elucidate the theory of solubilization chromatography 相似文献
65.
Ollagnier CM Perera SD Fitchett CM Draper SM 《Dalton transactions (Cambridge, England : 2003)》2008,(2):283-290
2-(2'-Pyridyl)-3,4,5,6-tetraphenylpyridine 2 (HL), a ligand with both N,N-bidentate and N,N,C-terdentate coordination potential, was prepared in excellent yield by the Diels-Alder [2+4] cycloaddition of 2-cyanopyridine and tetraphenylcyclopentadien-1-one. Monometallic Pd(II) and Rh(III) complexes were formed which exhibit both types of ligand coordination (trans-[RhCl2(L)(NCMe)] 3, cis-[RhCl(L)(NCMe)2]PF6, cis-[RhCl2(HL)2]PF6 6, [RhCl(L)(HL)]PF6 7, [Rh(L)2]PF6 8, [Pd(OAc)(L)] 9 and [Pd(eta3-methallyl)(HL)]PF6) 10. The molecular structures of the ligand and six complexes, including the chloro-bridged dimer [RhCl(L)(micro-Cl)]2 5, were obtained by single crystal X-ray diffraction. 相似文献
66.
Draper WM Behniwal P Wijekoon D 《Rapid communications in mass spectrometry : RCM》2008,22(17):2613-2620
The direct determination of dialkyl phosphates (DAPs) in water by strong anion-exchange (SAX) liquid chromatography/atmospheric pressure chemical ionization (APCI) mass spectrometry was investigated. The SAX high-performance liquid chromatography (HPLC) column was eluted with methanol/water gradients containing ammonium formate (AF) separating the DAPs which included six dimethyl- and diethyl-substituted phosphates, thiophosphates, and dithiophosphates. The high buffer concentrations required for separation were compatible with -ve APCI, but in +ve APCI the DAPs were unstable giving anomalous ions such as [M+15]+ and [M+29]+. These ions are believed to result from ion molecule reactions with CH3OH2+ in the plasma. DAPs are very stable in -ve APCI being detected as abundant [M-H](-) ions, even with 200 mM AF. At higher AF concentration formate clusters ([M+45](-) and [M+91](-)) were seen. Fragmentation by collision-activated dissociation (CAD) was more efficient for deprotonated ethyl-substituted DAPs which lost ethylene followed by ethanol. APCI instrument detection limits were in the low ng/mL range and the response was highly linear. Isotope dilution quantitation using d10-diethyl dithiophosphate (DEDTP) as an internal standard produced an instrument detection limit of 2 ng DEDTP/mL and method detection limit (MDL) of 9.3 ng/mL with accuracy of 99% (spike concentration, 25 ng/mL). DAP mixtures required storage in cold, dry conditions and alcohol solvents should be avoided because of solvolysis reactions. 相似文献
67.
Ohne Zusammenfassung 相似文献
68.
John C. Draper 《Fresenius' Journal of Analytical Chemistry》1868,7(1):388-389
Ohne Zusammenfassung 相似文献
69.
70.
Alok Goel David Savage Tara Hogan Sylvia M. Draper Peter T.M. Kenny 《Journal of organometallic chemistry》2006,691(22):4686-4693
A series ofN-para-ferrocenyl benzoyl dipeptide esters 2-5 were prepared by coupling para-ferrocenyl benzoic acid (1) to the dipeptide ethyl esters using the conventional 1,3-dicyclohexylcarbodiimide (DCC), 1-hydroxybenzotriazole (HOBt) protocol. The dipeptides employed in the synthesis were Ala-Gly(OEt) (2), Ala-Ala(OEt) (3), Ala-Leu(OEt) (4) and Ala-Phe(OEt) (5). The compounds were fully characterized by a range of NMR spectroscopic techniques, electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS). In addition the X-ray crystal structure of the l-alanine-glycine derivative 2 has been determined. 相似文献