全文获取类型
收费全文 | 337篇 |
免费 | 8篇 |
专业分类
化学 | 196篇 |
晶体学 | 8篇 |
力学 | 3篇 |
数学 | 44篇 |
物理学 | 94篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2017年 | 3篇 |
2016年 | 10篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 17篇 |
2012年 | 14篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 15篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 13篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1983年 | 4篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1972年 | 7篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1937年 | 2篇 |
1931年 | 2篇 |
1929年 | 3篇 |
1919年 | 2篇 |
1913年 | 2篇 |
1912年 | 6篇 |
1911年 | 2篇 |
排序方式: 共有345条查询结果,搜索用时 0 毫秒
61.
ÜMMÜHAN OCAK HALIT KANTEKIN YAŞAR GÖK H. BASIR ŞENTÜRK 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(1-2):87-91
The selective liquid–liquid extraction of various transition metal cations from the aqueous phase to the organic phase was carried out using a 14-membered N2O2S2-macrobicycle. Metal picrates such as Pb2+, Co2+, Zn2+, Ni2+,Cu2+ and Cd2+ were used in this extraction studies. It was found that the ligand showed moderate selectivity towards Pb2+ only among the other metals. The extraction constant (log K
ex) was determined to be 13.8 for Pb2+ complex. 相似文献
62.
H. v. Euler C. Zimmerlund C. van der Hoeven R. Riwlin A. Fodor A. K. Goard J. Effront F. König P. Surun J. M. Kolthoff A. S. Coolidge W. Bachmann L. Maier O. Wolff J. E. Teeple und P. Mahler 《Fresenius' Journal of Analytical Chemistry》1929,78(7-8):297-304
Ohne Zusammenfassung 相似文献
63.
Knudsen KR Bachmann S Jørgensen KA 《Chemical communications (Cambridge, England)》2003,(20):2602-2603
The half-transamination reaction of alpha-keto esters with pyridoxamine or 4-picolylamine was found to be catalysed by different metal catalysts in organic solvents giving moderate yields and enantioselectivities of up to 37% ee for methyl-3-indole pyruvate. 相似文献
64.
65.
66.
The cationic [RuCl(PNNP)]+ catalysts containing tetradentate ligands with a P2N2 donor set (PNNP) show strong electronic effects in the cyclopropanation of para‐substituted styrenes. The reactivity trend confirms that the carbene transfer to the olefin has electrophilic character. Linear free‐energy relationships are observed for the relative reactivity, the cis/trans selectivity, and for the enantioselectivity (of the cis‐cyclopropane). The linear correlation between log (kX/kH) and σ shows a large value of ρ (−2.4), which is indicative of significant charge buildup in the transition state of the carbene transfer to the olefin. All the relevant parameters (reactivity, diastereoselectivity, and enantioselectivity) increase with the increasing electron density at the C=C bond. To define the scope of the [RuCl(PNNP)]+ catalysts, 1‐ and 2‐substituted styrenes, and oct‐1‐ene were also investigated. 相似文献
67.
68.
69.
Aaij R Abellan Beteta C Adeva B Adinolfi M Adrover C Affolder A Ajaltouni Z Albrecht J Alessio F Alexander M Alkhazov G Alvarez Cartelle P Alves AA Amato S Amhis Y Anderson J Appleby RB Aquines Gutierrez O Archilli F Arrabito L Artamonov A Artuso M Aslanides E Auriemma G Bachmann S Back JJ Bailey DS Balagura V Baldini W Barlow RJ Barschel C Barsuk S Barter W Bates A Bauer C Bauer T Bay A Bediaga I Belogurov S Belous K Belyaev I Ben-Haim E Benayoun M Bencivenni G Benson S Benton J Bernet R 《Physical review letters》2012,108(16):161801
First observations of the Cabibbo-suppressed decays B(0) → D(+)K(-)π(+)π(-) and B(-) → D(0)K(-)π(+)π(-) are reported using 35 pb(-1) of data collected with the LHCb detector. Their branching fractions are measured with respect to the corresponding Cabibbo-favored decays, from which we obtain B(B(0) → D(+)K(-)π(+)π(-))/B(B(0) → D(+)π(-)π(+)π(-))=(5.9±1.1±0.5)×10(-2) and B(B(-) → D(0)K(-)π(+)π(-))/B(B(-) → D(0)π(-)π(+)π(-))=(9.4±1.3±0.9)×10(-2), where the uncertainties are statistical and systematic, respectively. The B(-) → D(0)K(-)π(+)π(-) decay is particularly interesting, as it can be used in a similar way to B(-) → D(0)K(-) to measure the Cabibbo-Kobayashi-Maskawa phase γ. 相似文献
70.
Aaij R Abellan Beteta C Adeva B Adinolfi M Adrover C Affolder A Ajaltouni Z Albrecht J Alessio F Alexander M Alkhazov G Alvarez Cartelle P Alves AA Amato S Amhis Y Anderson J Appleby RB Aquines Gutierrez O Archilli F Arrabito L Artamonov A Artuso M Aslanides E Auriemma G Bachmann S Back JJ Bailey DS Balagura V Baldini W Barlow RJ Barschel C Barsuk S Barter W Bates A Bauer C Bauer T Bay A Bediaga I Belogurov S Belous K Belyaev I Ben-Haim E Benayoun M Bencivenni G Benson S Benton J Bernet R 《Physical review letters》2012,108(18):181806
The angular distributions and the partial branching fraction of the decay B0 → K*0 μ+ μ- are studied by using an integrated luminosity of 0.37 fb(-1) of data collected with the LHCb detector. The forward-backward asymmetry of the muons, A(FB), the fraction of longitudinal polarization, F(L), and the partial branching fraction dB/dq2 are determined as a function of the dimuon invariant mass. The measurements are in good agreement with the standard model predictions and are the most precise to date. In the dimuon invariant mass squared range 1.00-6.00 GeV2/c4, the results are A(FB)=-0.06(-0.14)(+0.13)±0.04, F(L)=0.55±0.10±0.03, and dB/dq2=(0.42±0.06±0.03)×10(-7) c4/GeV2. In each case, the first error is statistical and the second systematic. 相似文献