全文获取类型
收费全文 | 1082篇 |
免费 | 21篇 |
国内免费 | 4篇 |
专业分类
化学 | 550篇 |
晶体学 | 26篇 |
力学 | 55篇 |
数学 | 109篇 |
物理学 | 367篇 |
出版年
2022年 | 14篇 |
2021年 | 14篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 17篇 |
2016年 | 32篇 |
2015年 | 15篇 |
2014年 | 22篇 |
2013年 | 60篇 |
2012年 | 47篇 |
2011年 | 60篇 |
2010年 | 45篇 |
2009年 | 41篇 |
2008年 | 65篇 |
2007年 | 45篇 |
2006年 | 58篇 |
2005年 | 46篇 |
2004年 | 32篇 |
2003年 | 26篇 |
2002年 | 25篇 |
2001年 | 19篇 |
2000年 | 23篇 |
1999年 | 14篇 |
1998年 | 10篇 |
1997年 | 13篇 |
1996年 | 14篇 |
1995年 | 19篇 |
1994年 | 20篇 |
1993年 | 28篇 |
1992年 | 24篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1964年 | 5篇 |
1955年 | 5篇 |
排序方式: 共有1107条查询结果,搜索用时 0 毫秒
11.
T. Datta Samanta S. Laskar D. Nayak S. Lahiri 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):323-325
Binding ability of mercury, thallium, lead and bismuth with Erythrina variegata seed protein have been investigated using tracer packet technique. Due to the lack of standard methods, inter-comparisons
have been made among three different approaches, like trichloroacetic acid (TCA) precipitation, isoelectric precipitation
and dialysis of protein after incubation with the metals. Good agreement was observed for all the cases except that of lead. 相似文献
12.
A new series of group 6 carbonyl complexes of N-[(2-pyridyl)methyliden]-α (or β)-aminonaphthalene (α/β-NaiPy) are described in this work. The complexes are formulated as cis-[M(CO)4(α/β-NaiPy)] by elemental, mass and other spectroscopic data. The complexes show emission spectra at room temperature and their quantum yield lies between 0.4 and 0.5. All the complexes exhibit negative solvatochromism. Cyclic voltammetry shows metal centred oxidation and ligand reductions. 相似文献
13.
Sambhu N. Datta 《International journal of quantum chemistry》1995,56(2):91-95
Relativistic basis sets for first-row atoms have been constructed by using the near-Hartree–Fock (nonrelativistic) eigenvectors calculated by Partridge. These bases generate results of near-Dirac–Hartree–Fock quality. Relativistic total and orbital energies, relativistic corrections to the total energy, and magnetic interaction energies for the first-row atoms have been presented. The smallest Gaussian expansions (13s8 p expansions) yield Dirac–Hartree–Fock total energies accurate through six significant digits, while the largest expansions (18s13p expansions) give these energies accurate through seven significant digits. These results are more accurate than some of the results reported earlier, particularly for the open-shell atoms, indicating that the basis employed is reasonably economical for relativistic calculations. © 1995 John Wiley & Sons, Inc. 相似文献
14.
Chirag Patel Vishwanada Sastry Datta Madamwar 《Applied biochemistry and biotechnology》1996,56(1):89-94
To obtain enriched methane content and improve the anaerobic digestion of a mixture of cattle dung, poultry waste, and cheese
whey, the effect of various doses of Tegoprens: T-3012, T-3022, T-5842, T-5843, T-5851, T-5852 has been studied, in bench-scale
digesters. Among them, Tegoprens 3022 showed more than a 45% increase in gas production with higher methane content. 相似文献
15.
16.
17.
18.
19.
Chemosensors for the marine toxin saxitoxin 总被引:1,自引:0,他引:1
Gawley RE Pinet S Cardona CM Datta PK Ren T Guida WC Nydick J Leblanc RM 《Journal of the American Chemical Society》2002,124(45):13448-13453
Eleven anthracylmethyl crown ethers have been synthesized and evaluated as fluorescence sensors for the marine toxin saxitoxin. Fluorescence enhancement data are consistent with a 1:1 binding complex for all crowns. The binding constants are in the range of 10(4) M(-)(1) in ammonium phosphate buffer (pH 7.1) in 80% ethanol solvent. Selectivity for sensing saxitoxin versus several organic analytes has been demonstrated for the first time. Possible modes of binding are presented, and relevance to saxitoxin monitoring programs are discussed. 相似文献
20.
Sachindra Kumar Datta Sachindra Nath Saha 《Fresenius' Journal of Analytical Chemistry》1961,184(3):177-184
Summary A chromotropic azo dye, DSNADNS, prepared from chromotropic acid and 1-amino-8-naphthol-3,6-disulfonic acid has been found to produce quantitative precipitation of zirconium in acid medium. The blue-violet complex formed is insoluble in all organic solvents commonly used for solvent extraction work, but is soluble in a number of liquid organic bases and solutions of ammonium salts in water showing pink to violet colouration. Spectrophotometric studies as to the nature of the complex in pyridine, triethanolamine ammonium acetate, oxalate and carbonate solutions and the analytical possibility of these solutions have been made. The complex appears to decompose in pyridine, ammonium acetate and ammonium oxalate solutions, but it is fairly stable in ammonium carbonate and triethanolamine solutions. The absorbance peaks of the dye in these solutions occur at 500 and 520 nm respectively, while the complex in triethanolamine and ammonium carbonate both shows absorbance maxima at 540 nm. The solution of the complex in these two solvents obeys Beer's law within a concentration range 4 to 25 mg of zirconium per litre. The molar absorbance coefficients of the complex in triethanolamine and ammonium carbonate are respectively 686 and 823, which indicate poor sensitivity. The solution of the complex in the former solvent is more stable than that in the latter and an analytical procedure for the spectrophotometric determination of zirconium, with little interference from foreign ions, may be developed with ease in the triethanolamine solution.
Zusammenfassung Ein Azofarbstoff der Chromotropsäure, DSNADNS, der aus Chromotropsäure und 1-Amino-8-naphthol-3,6-disulfonsäure dargestellt werden kann, ergibt mit Zirkonium in saurer Lösung eine quantitative Fällung. Der blauviolett gefärbte Komplex ist in allen üblichen organischen Lösungsmitteln unlöslich, löst sich jedoch in einigen flüssigen organischen Basen sowie wäßrigen Lösungen von Ammoniumsalzen mit rosa bis violetter Färbung. Die Lösungen des Komplexes in Pyridin, Triäthanolamin sowie in Ammoniumacetat, -oxalat und -carbonatlösungen und ihre analytische Verwendbarkeit werden spektrophotometrisch untersucht. In Pyridin sowie in Ammoniumacetat und -oxalatlösungen scheint sich der Komplex zu zersetzen, während er in Triäthanolamin und Ammoniumcarbonatlösungen ziemlich beständig ist. Das Absorptionsmaximum des Farbstoffs in diesen beiden Lösungsmitteln liegt bei 500 bzw. 520 nm, der Komplex weist in beiden Fällen ein Maximum bei 540 nm auf. Das Beersche Gesetz wird in beiden Lösungsmitteln von 4–25 mg Zr/l erfüllt. Der molare Absorptionskoeffizient beträgt 686 bzw. 823. Die Lösung des Komplexes in Triäthanolamin ist stabiler als in Ammoniumcarbonatlösung. Eine spektrophotometrische Bestimmung von Zirkonium, die nur wenig von Fremdionen gestört wird, könnte daher gut in Triäthanolaminlösung durchgeführt werden.相似文献