首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   421篇
  免费   17篇
化学   363篇
晶体学   2篇
力学   2篇
数学   6篇
物理学   65篇
  2022年   6篇
  2021年   4篇
  2020年   9篇
  2019年   8篇
  2018年   4篇
  2016年   6篇
  2015年   11篇
  2014年   10篇
  2013年   14篇
  2012年   18篇
  2011年   30篇
  2010年   11篇
  2009年   17篇
  2008年   18篇
  2007年   12篇
  2006年   25篇
  2005年   14篇
  2004年   9篇
  2003年   9篇
  2002年   11篇
  2001年   9篇
  2000年   12篇
  1999年   8篇
  1997年   4篇
  1994年   6篇
  1993年   3篇
  1992年   6篇
  1991年   4篇
  1990年   8篇
  1989年   4篇
  1988年   9篇
  1987年   12篇
  1986年   6篇
  1985年   16篇
  1984年   11篇
  1983年   5篇
  1982年   6篇
  1981年   7篇
  1980年   5篇
  1979年   6篇
  1978年   6篇
  1977年   5篇
  1976年   4篇
  1975年   3篇
  1973年   2篇
  1968年   2篇
  1967年   3篇
  1966年   5篇
  1929年   2篇
  1927年   2篇
排序方式: 共有438条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Valence band photoemission spectra of black phosphorus have shown anomalous behavior at the excitation of 2p core-excitons. The intensity of the 2.7 ev peak shows a clear Fano type interference due to a direct recombination of core-excitons leaving one hole in valence bands. Besides, strong enhancement of the 10.8 eV peak is interpreted as due to a core-exciton induced resonance with two-hole final states. The role of core-excitons as intermediate states for photoemission processes is newly revealed in the experiments.  相似文献   
55.
The (N-benzyl-l-leucinato) copper(II) complex was shown pH titration to coordinate l-amino acids more strongly than d enantiomers. A chiral polymer complex, containing N-alkylated amino acid residue and copper(II) ion, was used partially to resolve some optically active amino acids. Unlike the (N-benzyl-l-amino acidate)-copper(II) complex, the polymer—copper(II) complex coordinates d-amino acids more strongly than l-enantiomers; the effect was explained by formation of (N,N-dialkylated-amino acidate) copper(II) complex in the polymer.  相似文献   
56.
Summary A sensitive method for the hydride generation and graphite tube furnace atomic absorption spectrometric measurements with a reducing tube using mixed gas (CH4 10% + Ar 90%) as sweeper gas has been developed for the determination of germanium. Germanium hydrides were generated in a horizontal glass tube, in which a pellet of NaBH4 was placed. 0.61/min of sweeper gas flow rate, 2,700° C of atomization temperature and 2.5–3 M of acidity range were the best experimental conditions. The strong supression of the germanium signal by Ni and Co was effectively eliminated with 1,10-phenanthroline and thiosemicarbazide was comparatively effective for Au. The reducing tube used in this technique is extremely simple and can be connected to all the types of graphite furnaces. A detection limit of 2 ng was obtained with a precision of 3–4%
Germaniumbestimmung durch Hydriderzeugung im Reduktionsrohr und nachfolgende Graphitofen-AAS mit CH4/Ar als Spülgas
Zusammenfassung Bei dem beschriebenen Verfahren werden die Hydride in einem horizontalen Glasrohr erzeugt, das eine NaBH4-Perle enthält. Als optimale experimentelle Bedingungen ergaben sich: Spülgas (0,61/min) aus 10% CH4 und 90% Ar, Atomisierungstemperatur 2700° C, 2,5–3 M Säure. Die starke Beeinflussung des Ge-Signals durch Ni und Co wurde mit Hilfe von 1,10-Phenanthrolin eliminiert, die Störung durch Au mit Hilfe von Thiosemicarbazid. Das verwendete Reduktionsrohr ist sehr einfach und kann für alle Arten von Graphitöfen benutzt werden. Die Nachweisgrenze beträgt 2 ng, die Reproduzierbarkeit 3–4%.


Paper read at the Meeting of the Japan Society for Analytical Chemistry, June 1982  相似文献   
57.
Highly reversible, safe lithium secondary batteries that use imidazolium-cation-based room-temperature ionic liquid as an electrolyte and lithium metal as an anode material were realized by the molecular design. To achieve higher reduction stability, an electron-donating substituent was introduced to promote charge delocalization in the imidazolium cation of room-temperature ionic liquids.  相似文献   
58.
For the purpose of realizing high-voltage, high-capacity, long-life and safe rechargeable batteries, a lithium secondary battery that uses high-voltage stable ZrO2-coated LiCoO2 cathode powder and a nonvolatile high-safety room temperature ionic liquid was fabricated.  相似文献   
59.
Double charged pion photoproductions from the deuteron have been studied at Research Center for Electron Photon Science (ELPH), Tohoku University. Tagged photon beams in an energy range of 0.67 ≤ E γ ≤ 1.08 GeV were impinged on the liquid deuteron target. Produced charged particles were observed with the Neutral Kaon Spectrometer2 (NKS2). The γ dπ + π ? d process was clearly separated among the three charged tracks. We obtained the photon energy dependence of the normalized yields of this process.  相似文献   
60.
Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K 0 with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + dK 0 + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K 1, as ~ ?1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K + Λ.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号