全文获取类型
收费全文 | 608篇 |
免费 | 19篇 |
国内免费 | 2篇 |
专业分类
化学 | 415篇 |
晶体学 | 6篇 |
力学 | 10篇 |
数学 | 41篇 |
物理学 | 157篇 |
出版年
2023年 | 9篇 |
2022年 | 10篇 |
2021年 | 12篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 10篇 |
2016年 | 27篇 |
2014年 | 14篇 |
2013年 | 53篇 |
2012年 | 34篇 |
2011年 | 42篇 |
2010年 | 22篇 |
2009年 | 20篇 |
2008年 | 24篇 |
2007年 | 17篇 |
2006年 | 12篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 6篇 |
1999年 | 5篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 16篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1978年 | 4篇 |
1977年 | 11篇 |
1976年 | 12篇 |
1975年 | 12篇 |
1974年 | 7篇 |
1973年 | 7篇 |
1972年 | 4篇 |
1971年 | 7篇 |
1968年 | 4篇 |
1966年 | 6篇 |
1962年 | 8篇 |
1958年 | 4篇 |
排序方式: 共有629条查询结果,搜索用时 15 毫秒
21.
K. -H. Speidel M. Knopp W. Karle M. Mayr F. Hagelberg H. -J. Simonis J. Gerber P. N. Tandon 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,6(1):43-48
Effective transient magnetic fields have been measured for single-electron carbon and oxygen ions traversing ferromagnetic Ni and Gd hosts, respectively. The deduced values ofK-shell polarization are well explained considering spin exchange scattering as a dominant mode of polarization. 相似文献
22.
23.
Summary Several new complexes of Sb(III) and Bi(III) with thiosemicarbazones of furfuraldehyde, thiophene-2-carbaldehyde, indol-3-carbaldehyde and pyridine-2-carbaldehyde have been prepared and characterized by elemental analysis, conductivity, molecular weight determination and IR,1H-and13C-NMR spectral studies. The ligands form complexes of the typeMX
3
L[M=Sb(III) or Bi(III);X=chloride;L=ligand] which are found to be non-electrolytes inDMF. Spectral data indicate that the thiosemicarbazones act as bidentate ligands through the azomethine nitrogen and sulphur.
Synthese und Strukturuntersuchungen an Komplexen von Sb(III) and Bi(III) mit Thiosemicarbazonen
Zusammenfassung Es wurden einige neue Komplexe von Sb(III) und Bi(III) mit Tiosemicarbazonen von Furfural, Thiophen-2-carbaldehyd, Indol-3-carbaldehyd und Pyridin-2-carbaldehyd hergestellt und mittels Elementaranalyse, Leitfähigkeitsmessungen, Molekulargewichtsbestimmungen und IR-,1H- bzw.13C-NMR-Spektroskopie charakterisiert. Die Komplexe sind vom TypMX 3 L[M=Sb(III) oder Bi(III);X=Chlorid;L=Ligand] und sind inDMF Nichtelektrolyten. Die spektroskopischen Daten zeigen, daß die Thiosemicarbazone als zweizähnige Liganden über den Azomethin-Stickstoff und Schwefel wirken.相似文献
24.
Different molar reactions of Fe(OPr1)3, and FeCl3 with benzothiazolines having an NSH donor system. derived by the condensation ofo-aminothiophenol with heterocyclic aldehydes. viz. pyridine-2-aldehyde. furfuraldehyde and thiophene-2-aldehyde. lead to the
formation of [Fe.Pr1(NS)2]2, [Fc(NS)3] and [Fe(NS)2Cl| type of complexes. The resulting derivatives have been characterized by elemental analysis, conductivity measurements,
molecular weight determinations and magnetic studies. IR, electronic, M?ssbauer and ESR spectral data have been used to deduce
the structures of the resulting derivatives. 相似文献
25.
L. C. Tribedi K. G. Prasad P. N. Tandon 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(2):143-148
Single and double K-vacancy fractions at sulphur ions in Fe and Ni are measured for ion velocities between 7v 0 and 14v 0 (v 0=c/137) using the probe layer technique. The derived values for the degree of polarization of these ions from the available transient magnetic field data at a velocity of 8v 0 in Fe and Ni agrees with the general trends seen for light ions. 相似文献
26.
The condensation of 4-thiaheptane-2,6-dione with triethylenetetramine does not produce the macrocycle 1-thia-3,14-dimethyl-4,7,10-13-tetrazacyclopentadeca-3,13-diene; instead two molecules of the dione condense with one of the amine to give the title compound. 相似文献
27.
Ginotra SK Chhikara BS Singh M Chandra R Tandon V 《Chemical & pharmaceutical bulletin》2004,52(8):989-991
Mild, efficient and eco-friendly oxidation of 17alpha-methylandrostan-3beta-17beta-diol (1) has been studied with three different reagents viz. pentavalent iodine reagent 2-iodoxy benzoic acid (IBX) in DMSO at 65 degrees C, sodium hypochlorite and H2O2/Na2WO4 under phase transfer conditions to give 17beta-hydroxy-17alpha-methylandrostan-3-one (mestanolone 2), a drug intermediate as oxidized product. The H2O2/Na2WO4/PTC gave mestanolone in high yield and purity whereas sodium hypochlorite/PTC system yielded some chlorinated material along with the mestanolone. However, 1 with 2.5 equivalent of IBX gave 17beta-hydroxy-17alpha-methyl-Delta1-androsten-3-one (3) under the similar reaction conditions in good yield and single step reaction. 相似文献
28.
p-Ethoxychrysoidine is studied as adsorption indicator in the direct titration of silver with iodide, bromide, thiocyanate and chloride at pH 4–5. The explanation given by Schulek and Pungor for the colour changes has been modified in the light of compound formation on the surface of the precipitate. The silver compound of p-ethoxychrysoidine has been isolated ; its behaviour provides a suitable explanation for the colour changes as well as the pH changes in the titrations. 相似文献
29.
Multi-ligand self-assembly to attain the AgI-N-heterocyclic carbene (NHC)-built hexanuclear organometallic cages of composition [Ag6( 3 a , b )4](PF6)6 from the reaction of benzimidazole-derived tris(azolium) salts [H3- 3 a , b ](PF6)3 with Ag2O was achieved. The molecular structures of the cages were established by X-ray diffraction studies along with NMR and MS analyses. The existence of a single assembly in solution was supported by diffusion-ordered spectroscopy (DOSY) 1H NMR spectra. Further, transmetalation reactions of these self-assembled complexes, [Ag6( 3 a , b )4](PF6)6, with CuI/AuI-ions provided various coinage metal-NHC complexes having diverse molecular compositions, which included the first example of a hexanuclear CuI-dodecacarbene complex, [Cu6( 3 b )4](PF6)6. 相似文献
30.