全文获取类型
收费全文 | 595篇 |
免费 | 12篇 |
专业分类
化学 | 421篇 |
晶体学 | 11篇 |
力学 | 21篇 |
数学 | 13篇 |
物理学 | 141篇 |
出版年
2020年 | 6篇 |
2019年 | 13篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 9篇 |
2013年 | 20篇 |
2012年 | 28篇 |
2011年 | 24篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 29篇 |
2007年 | 25篇 |
2006年 | 24篇 |
2005年 | 19篇 |
2004年 | 23篇 |
2003年 | 9篇 |
2002年 | 33篇 |
2001年 | 9篇 |
2000年 | 12篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 12篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 14篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 13篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1972年 | 5篇 |
1968年 | 6篇 |
1967年 | 4篇 |
1965年 | 4篇 |
1958年 | 4篇 |
1955年 | 4篇 |
1934年 | 4篇 |
1914年 | 4篇 |
1913年 | 3篇 |
排序方式: 共有607条查询结果,搜索用时 15 毫秒
141.
Franz Rudolf Kunz Hellmut Jork Hans Erich Keller 《Fresenius' Journal of Analytical Chemistry》1993,346(6-9):847-851
Summary A newly developed thin-layer chromatographic method (TLC) for the quantitative determination of netilmicin in serum is described and compared with fluorescence polarization immunoassay (FPIA). The TLC procedure involves solid-phase extraction of the aminoglycoside from serum and chromatography on reversed-phase thin layer. Post-chromatographic derivatization is carried out using 2,2-diphenyl-1-oxa-3-oxonia-2-boratanaphthalene (DOOB) as fluorescence reagent. The calibration curve for netilmicin in serum is linear in the range 1.0–5.0 g/ml and the detection limit is about 0.2 g/ml (correlation coefficient r=0.9963, mean coefficient of variation VXO=±5.3 %). A total of 25 serum samples from patients treated with netilmicin was measured by TLC and the results were compared with those of FPIA (Abbott TDx). There is no statistically significant difference between the two procedures (y=–0.35+1.094·x, Passing/Bablok). Thus the TLC-procedure is an alternative for the determination of netilmicin in serum, that possesses the necessary sensitivity of other comparable methods.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday. 相似文献
142.
143.
144.
Ohne ZusammenfassungErste Mitteilung: Hans Meyer, Monatshefte für Chemie,30, 165 (1909). — Zweite Mitteilung: Hans Meyer, R. Bondy und A. Eckert, Monatshefte für Chemie,33, 1447 (1912). 相似文献
145.
Ohne Zusammenfassung 相似文献
146.
147.
C. Cierpka T. Weier G. Gerbeth M. Uhlemann K. Eckert 《Journal of Solid State Electrochemistry》2007,11(6):687-701
In two different cylindrical electrochemical cells, copper deposition and dissolution in the presence of a magnetic field
mostly parallel to the electric field was investigated. Particle image velocimetry measurements show that even under such
a field configuration where Lorentz forces are often a priori neglected may in fact dominate the flow. Further, depending
on the electrode radius, a reversal of the secondary flow was found. This feature can be explained by the different Lorentz
force configurations calculated from the magnetic field and the primary current distributions. The components of the magnetic
field were determined by means of a traversed Hall probe and were calculated by a commercial finite element package. Experimentally
and numerically determined field distributions match very well. A good agreement between the measured and calculated velocity
distributions was also found, suggesting that in the present case the effect of the Lorentz force alone is sufficient to explain
the magnetic field influence on the flow.
Contribution to the special issue “Magnetic field effects in Electrochemistry” 相似文献
148.
An analogy is explored between a setup of three atomic traps coupled via tunneling and an internal atomic three-level system interacting with two laser fields. Within this scenario we describe a STIRAP like process which allows to move an atom between the ground states of two trapping potentials and analyze its robustness. This analogy is extended to other robust and coherent transport schemes and to systems of more than a single atom. Finally it is applied to manipulate external degrees of freedom of atomic wave packets propagating in waveguides. 相似文献
149.
Anna-Lena Wübker Dr. Jonas Koppe Dr. Henrik Bradtmüller Dr. Lukas Keweloh Dr. Damian Pleschka Prof. Werner Uhl Prof. Michael Ryan Hansen Prof. Hellmut Eckert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(52):13249-13257
The first comprehensive solid-state nuclear magnetic resonance (NMR) characterization of geminal alane-phosphane frustrated Lewis pairs (Al/P FLPs) is reported. Their relevant NMR parameters (isotropic chemical shifts, direct and indirect 27Al-31P spin-spin coupling constants, and 27Al nuclear electric quadrupole coupling tensor components) have been determined by numerical analysis of the experimental NMR line shapes and compared with values computed from the known crystal structures by using density functional theory (DFT) methods. Our work demonstrates that the 31P NMR chemical shifts for the studied Al/P FLPs are very sensitive to slight structural inequivalences. The 27Al NMR central transition signals are spread out over a broad frequency range (>200 kHz), owing to the presence of strong nuclear electric quadrupolar interactions that can be well-reproduced by the static 27Al wideband uniform rate smooth truncation (WURST) Carr-Purcell-Meiboom-Gill (WCPMG) NMR experiment. 27Al chemical shifts and quadrupole tensor components offer a facile and clear distinction between three- and four-coordinate aluminum environments. For measuring internuclear Al⋅⋅⋅P distances a new resonance-echo saturation-pulse double-resonance (RESPDOR) experiment was developed by using efficient saturation via frequency-swept WURST pulses. The successful implementation of this widely applicable technique indicates that internuclear Al⋅⋅⋅P distances in these compounds can be measured within a precision of ±0.1 Å. 相似文献
150.