全文获取类型
收费全文 | 564篇 |
免费 | 42篇 |
专业分类
化学 | 374篇 |
晶体学 | 15篇 |
力学 | 2篇 |
数学 | 79篇 |
物理学 | 136篇 |
出版年
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 12篇 |
2016年 | 16篇 |
2015年 | 20篇 |
2014年 | 22篇 |
2013年 | 29篇 |
2012年 | 24篇 |
2011年 | 30篇 |
2010年 | 11篇 |
2009年 | 12篇 |
2008年 | 15篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 13篇 |
2004年 | 10篇 |
2003年 | 16篇 |
2002年 | 12篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 15篇 |
1997年 | 7篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1976年 | 4篇 |
1975年 | 8篇 |
1973年 | 7篇 |
1969年 | 7篇 |
1965年 | 4篇 |
1934年 | 4篇 |
1912年 | 4篇 |
排序方式: 共有606条查询结果,搜索用时 62 毫秒
61.
Adolf Franke Alfred Kroupa Solon Hadzidimitriu 《Monatshefte für Chemie / Chemical Monthly》1933,62(1-2):119-130
Ohne Zusammenfassung 相似文献
62.
63.
Zusammenfassung Die reaktionskinetische Untersuchung der Vorreife hat eine Reihe bereits bekannter Tatsachen best?tigt, vor allem aber die
eigenartige Erscheinung, da? die Reaktionsgeschwindigkeit asymptotisch abnimmt, einer Erkl?rung n?hergebracht. Niedermolekulare
Abbauprodukte müssen die Ursache für die Verlangsamung der Vorreife sein.
Die Aktivierungsenergie, die für einige Zellulosen bestimmt werden konnte, betr?gt übereinstimmend etwa 13340 cal. Für die
eindeutig feststellbaren Unterschiede in der Vorreifegeschwindigkeit sind demnach sich in der Sto?konstante ausdrückende Erscheinungen
verantwortlich.
Es hat den Anschein, da? gut filtrierbare Viskosen gebende Zellulosen in der Vorreife mehr Karboxylgruppen bilden bzw. diese
weniger leicht abspalten, da nicht mit Sicherheit anzugeben ist, ob dieses beobachtete Verh?ltnis prim?rer oder sekund?rer
Natur ist. 相似文献
64.
Ohne Zusammenfassung 相似文献
65.
Laura Senft Jamonica L. Moore Alicja Franke Katherine R. Fisher Andreas Scheitler Achim Zahl Ralph Puchta Dominik Fehn Sidney Ison Safaa Sader Ivana Ivanovi-Burmazovi Christian R. Goldsmith 《Chemical science》2021,12(31):10483
Reactivity assays previously suggested that two quinol-containing MRI contrast agent sensors for H2O2, [Mn(H2qp1)(MeCN)]2+ and [Mn(H4qp2)Br2], could also catalytically degrade superoxide. Subsequently, [Zn(H2qp1)(OTf)]+ was found to use the redox activity of the H2qp1 ligand to catalyze the conversion of O2˙− to O2 and H2O2, raising the possibility that the organic ligand, rather than the metal, could serve as the redox partner for O2˙− in the manganese chemistry. Here, we use stopped-flow kinetics and cryospray-ionization mass spectrometry (CSI-MS) analysis of the direct reactions between the manganese-containing contrast agents and O2˙− to confirm the activity and elucidate the catalytic mechanism. The obtained data are consistent with the operation of multiple parallel catalytic cycles, with both the quinol groups and manganese cycling through different oxidation states during the reactions with superoxide. The choice of ligand impacts the overall charges of the intermediates and allows us to visualize complementary sets of intermediates within the catalytic cycles using CSI-MS. With the diquinolic H4qp2, we detect Mn(iii)-superoxo intermediates with both reduced and oxidized forms of the ligand, a Mn(iii)-hydroperoxo compound, and what is formally a Mn(iv)-oxo species with the monoquinolate/mono-para-quinone form of H4qp2. With the monoquinolic H2qp1, we observe a Mn(ii)-superoxo ↔ Mn(iii)-peroxo intermediate with the oxidized para-quinone form of the ligand. The observation of these species suggests inner-sphere mechanisms for O2˙− oxidation and reduction that include both the ligand and manganese as redox partners. The higher positive charges of the complexes with the reduced and oxidized forms of H2qp1 compared to those with related forms of H4qp2 result in higher catalytic activity (kcat ∼ 108 M−1 s−1 at pH 7.4) that rivals those of the most active superoxide dismutase (SOD) mimics. The manganese complex with H2qp1 is markedly more stable in water than other highly active non-porphyrin-based and even some Mn(ii) porphyrin-based SOD mimics.Manganese complexes with polydentate quinol-containing ligands are found to catalyze the degradation of superoxide through inner-sphere mechanisms. The redox activity of the ligand stabilizes higher-valent manganese species. 相似文献
66.
The decomposition of chloroform by the combination of hydrodynamic and acoustic cavitation (Hydrodynamic-Acoustic-Cavitation/HAC) has been investigated. The flow rate and the hole diameter of the orifice plate remarkably affect the conversion of chloroform in the combined system. The conversion increases with increasing fluid velocity without any restriction. With a 2.8mm orifice plate the conversion reaches an optimal value. A synergistic effect has been obtained by the hybrid method of acoustic and hydrodynamic cavitation. The total synergistic effect achieves 17% and 73% per pass, respectively. The analysis of the energy efficiencies shows different results. Due to high optimization potential, this hybrid method can be visualized as a new step for wastewater treatment. 相似文献
67.
M. Daum P. FierlingerB. Franke P. GeltenbortL. Goeltl E. GutsmiedlJ. Karch G. KesslerK. Kirch H.-C. KochA. Kraft T. LauerB. Lauss E. PierreG. Pignol D. ReggianiP. Schmidt-Wellenburg Yu. SobolevT. Zechlau G. Zsigmond 《Physics letters. [Part B]》2011,704(5):456-460
Ultracold neutrons were stored in a volume, using a magnetic dipole field shutter. Radial confinement was provided by material walls. Low-field seeking neutrons were axially confined above the magnetic field. High-field seeking neutrons are trapped inside the magnetic field. They can systematically shift the measured neutron lifetime to lower values in experiments with magnetic confinement. 相似文献
68.
69.
70.