全文获取类型
收费全文 | 86篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 32篇 |
力学 | 12篇 |
数学 | 9篇 |
物理学 | 35篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有88条查询结果,搜索用时 15 毫秒
21.
Yvonnick Loidreau Carole Dubouilh‐Benard Pascal Marchand Marie‐Renée Nourrisson Muriel Duflos Catherine Buquet Cécile Corbière Thierry Besson 《Journal of heterocyclic chemistry》2013,50(5):1187-1197
A useful and rapid access to libraries of N‐arylbenzo[b]furo[3,2‐d]pyrimidin‐4‐amines ( 1 ) and their novel benzo[b]thieno[3,2‐d]pyrimidin‐4‐amine analogues ( 2 ) was investigated for the first time. Title compounds were obtained via microwave‐accelerated condensation and Dimroth rearrangement of suitable anilines with N′‐(2‐cyanaryl)‐N,N‐dimethylformimidamides obtained by reaction of benzo[b]furane and benzo[b]thiophene precursors with N,N‐dimethylformamide dimethyl acetal. This work also demonstrates that well‐controlled parameters offer comfortable use of microwave technology and are both safe and beneficial to the environment. Some products obtained in this article exhibit interesting in vitro antiproliferative effects. 相似文献
22.
23.
24.
A mixture of Li and Mg vapors at 900°C was optically pumped at 488 nm by an Ar+ ion laser. The resulting Li2 fluorescence and LiMg* excimer chemiluminescence intensities were analyzed to determine rate constants for the reactions Li2(B1π) + Mg → LiMg* + Li and LiMg* + Li → Li2(a3π) + Mg and the radiative decay rates of Li2(B1π) and LiMg*. 相似文献
25.
26.
27.
D.J. Benard 《Chemical physics letters》1975,35(2):167-171
Laser amplification by stimulated emission in the 001-100 vibrational-rotational band of CO2 has been continuously excited by transfer from the products of the oxidation of alkaline earth metal vapors in N2O. The sensitive detection of gain transverse to a 1 cm diameter flame was accomplished by intracavity measurements in a conventional CO2-EDL with the aid of two frequency modulation and synchronous detection. 相似文献
28.
29.
Commercial and military aircrafts or miniature aerial vehicles can suffer from massive flow separation when high angles of
attack are required. Single dielectric barrier discharge (DBD) actuators have demonstrated their capability of controlling
such a separated flow at low external velocity. However, the processes resulting in the improvement of the flight performances
remain unclear. In the present study, the reattachment process along the suction side of a NACA 0015 placed at an angle of
attack of 16° is experimentally investigated for an external velocity of 20 m/s (Re = 260,000). A single DBD actuator is mounted
at the leading edge of the model. The velocity fields above the suction side of the airfoil are measured by a high-speed acquisition
system (3 kHz). The results indicate that the baseline flow presents shed vortices that form at the leading edge and linearly
grow along the free shear layer axis. This vortex shedding is organized and exhibits a specific frequency of about 90 Hz.
The continuous actuation produces a partial flow reattachment up to 70% of the chord length. Temporal cross-correlation function
indicates the presence of a vortex shedding at the trailing edge of the controlled flow. Finally, the temporal analysis demonstrates
that the reattachment process requires 50 ms to reach a stabilized attached flow. The time-resolved analysis of the reattachment
suggests that the actuation by plasma discharge acts as a catalyser by reinforcing one of the coherent flow structures already
existing in the natural flow. 相似文献
30.
Control of diffuser jet flow: turbulent kinetic energy and jet spreading enhancements assisted by a non-thermal plasma discharge 总被引:2,自引:0,他引:2
An axisymmetric air jet exhausting from a 22-degree-angle diffuser is investigated experimentally by particle image velocimetry
(PIV) and stereo-PIV measurements. Two opposite dielectric barrier discharge (DBD) actuators are placed along the lips of
the diffuser in order to force the mixing by a co-flow actuation. The electrohydrodynamic forces generated by both actuators
modify and excite the turbulent shear layer at the diffuser jet exit. Primary air jet velocities from 10 to 40 m/s are studied
(Reynolds numbers ranging from 3.2 to 12.8 × 104), and baseline and forced flows are compared by analysing streamwise and cross-stream PIV fields. The mixing enhancement
in the near field region is characterized by the potential core length, the centreline turbulent kinetic energy (TKE), the
integrated value of the TKE over various slices along the jet, the turbulent Reynolds stresses and the vorticity fields. The
time-averaged fields demonstrate that an effective increase in mixing is achieved by a forced flow reattachment along the
wall of the diffuser at 10 m/s, whereas mixing enhancement is realized by excitation of the coherent structures for a primary
velocity of 20 and 30 m/s. The actuation introduces two pairs of contra-rotating vortices above each actuator. These structures
entrain the higher speed core fluid toward the ambient air. Unsteady actuations over Strouhal numbers ranging from 0.08 to
1 are also studied. The results suggest that the excitation at a Strouhal number around 0.3 is more effective to enhance the
turbulence kinetic energy in the near-field region for primary jet velocity up to 30 m/s. 相似文献