全文获取类型
收费全文 | 505篇 |
免费 | 4篇 |
国内免费 | 7篇 |
专业分类
化学 | 333篇 |
晶体学 | 4篇 |
力学 | 5篇 |
数学 | 54篇 |
物理学 | 120篇 |
出版年
2022年 | 10篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 16篇 |
2018年 | 15篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 33篇 |
2012年 | 20篇 |
2011年 | 26篇 |
2010年 | 10篇 |
2009年 | 16篇 |
2008年 | 23篇 |
2007年 | 26篇 |
2006年 | 39篇 |
2005年 | 19篇 |
2004年 | 34篇 |
2003年 | 14篇 |
2002年 | 15篇 |
2001年 | 19篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1970年 | 3篇 |
1959年 | 2篇 |
1944年 | 2篇 |
1910年 | 1篇 |
排序方式: 共有516条查询结果,搜索用时 9 毫秒
81.
Hitherto unknown dithioformic acid, HCSSH, has been produced by pyrolysis (300°C) of methanetrithiol, HC(SH)3, and identified by the microwave spectrum (18–40 GHz) of its most abundant species H12C32S32SH. Rotational transitions of this species in its ground state have been assigned to a trans and a cis rotamer. Both rotamers are planar, the trans conformer being the more stable by ca. 350 cm?1 mole?1. For each rotamer spectra of molecules in two vibrationally excited states have been assigned. Frequencies of transitions of importance for search for HCSSH in interstellar space are reported. 相似文献
82.
83.
84.
The present work reports isothermal gas/solid equilibration kinetics for Nb-doped TiO(2) (0.65 atom %) at elevated temperatures (1073-1298 K) within narrow ranges of oxygen activity spanning between 10(-13) Pa and 75 kPa. The equilibration kinetics were monitored using electrical conductivity measurements. The kinetic data were used to determine the chemical diffusion coefficient (D(chem)). D(chem) as a function of p(O(2)) exhibits a complex dependence, which is considered in terms of defect disorder and the related concentrations of electronic charge carriers. The activation energy of D(chem) in the p(O(2)) range 10 Pa < p(O(2)) < 75 kPa varies in the range 88.0-98.2 kJ/mol. It is important to note that the chemical diffusion coefficient in strongly reduced conditions [p(O(2)) = 10(-9) Pa] exhibits a negative temperature dependence of D(chem) (-67.2 kJ/mol). This finding indicates that under these conditions transport in a chemical potential gradient is consistent with metallic charge transport. 相似文献
85.
Børge Bak Niels A. Kristiansen Henrik Svanholt Arne Holm Steen Rosenkilde 《Chemical physics letters》1981,78(2):301-303
Microwave Spectra of 13CH212C80,78Se and 12CH213C80,78Se (selenoketene) are recorded. B 5-13C-1,2,3-selenadiazole all four species are formed. The 13C scrambling may take place via a three-membered ring, selenirene, but as expected its microwave spectrum was not observed. 相似文献
86.
Gaggelli E Janicka-Klos A Jankowska E Kozlowski H Migliorini C Molteni E Valensin D Valensin G Wieczerzak E 《The journal of physical chemistry. B》2008,112(1):100-109
Alzheimer's disease is a fatal neurodegenerative disorder involving the abnormal accumulation and deposition of peptides (amyloid-beta, Abeta) derived from the amyloid precursor protein. Here, we present the structure and the Zn2+ binding sites of human and rat Abeta(1-28) fragments in water/sodium dodecyl sulfate (SDS) micelles by using 1H NMR spectroscopy. The chemical shift variations measured after Zn2+ addition at T>310 K allowed us to assign the binding donor atoms in both rat and human zinc complexes. The Asp-1 amine, His-6 Ndelta, Glu-11 COO-, and His-13 Nepsilon of rat Abeta28 all enter the metal coordination sphere, while His-6 Ndelta, His-13, His-14 Nepsilon, Asp-1 amine, and/or Glu-11 COO- are all bound to Zn2+ in the case of human Abeta28. Finally, a comparison between the rat and human binding abilities was discussed. 相似文献
87.
Szyrwiel L Jankowska E Janicka-Klos A Szewczuk Z Valensin D Kozlowski H 《Dalton transactions (Cambridge, England : 2003)》2008,(44):6117-6120
Multi-histidine peptide fragments of zebra-fish prion protein are effective ligands for Zn(II) ions. Moreover the formation of a dinuclear complex species with a longer peptide can suggest the existence of the cooperative effect in the metal ion binding. 相似文献
88.
An electron-rich nickel(I) beta-diketiminate cleaves the E-NO bond of O-, S-, and N-organonitroso species to give the nickel nitrosyl [Me 3NN]NiNO along with dimeric nickel(II) alkoxide or thiolate complexes {[Me 3NN]Ni} 2(mu-E) 2 or the mononuclear nickel(II) amide [Me 3NN]NiNPh 2. This diamagnetic three-coordinate amide exhibits temperature-dependent NMR spectra due to a low-lying triplet state. 相似文献
89.
C. A. Londos M. S. Potsidi J. Bak‐Misiuk A. Misiuk V. V. Emtsev 《Crystal Research and Technology》2003,38(12):1058-1062
The effect of enhanced hydrostatic pressure following heat treatment on the evolution of point defects in neutron‐irradiated Czochralski‐grown silicon is investigated using infrared spectroscopy. The behavior of oxygen‐related defects, particularly of the VO and the VO2 centers, is mainly studied using samples subjected to heat treatment under hydrostatic pressure. It is observed that (1) pressure accelerates the annealing process of the VO defects and enhances the growth of the VO2 complexes and (2) the VO2 concentration is larger than expected from the corresponding decay of the VO defects. The faster decay of the VO defects is attributed to a pressure‐induced decrease of their migration energy. The larger VO2 concentration is also discussed. One possible explanation is that pressure stimulates an additional mechanism for the formation of the VO2 defects, which involves the reaction of oxygen dimers with vacancies. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
90.