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   259篇
  免费   0篇
  国内免费   4篇
化学   95篇
力学   4篇
数学   78篇
物理学   66篇
无线电   20篇
  2013年   8篇
  2012年   9篇
  2011年   6篇
  2010年   8篇
  2009年   6篇
  2008年   9篇
  2007年   19篇
  2006年   12篇
  2005年   11篇
  2004年   11篇
  2003年   10篇
  2002年   7篇
  2000年   4篇
  1999年   6篇
  1998年   2篇
  1997年   3篇
  1996年   5篇
  1995年   2篇
  1994年   3篇
  1993年   4篇
  1992年   2篇
  1991年   2篇
  1988年   3篇
  1986年   3篇
  1985年   4篇
  1984年   6篇
  1983年   6篇
  1982年   4篇
  1981年   6篇
  1980年   8篇
  1979年   6篇
  1978年   2篇
  1977年   3篇
  1976年   3篇
  1974年   2篇
  1973年   4篇
  1972年   3篇
  1971年   4篇
  1967年   4篇
  1958年   2篇
  1956年   3篇
  1948年   2篇
  1940年   3篇
  1939年   3篇
  1937年   2篇
  1932年   2篇
  1931年   2篇
  1927年   1篇
  1925年   1篇
  1924年   1篇
排序方式: 共有263条查询结果,搜索用时 15 毫秒
31.
32.
33.
We present the chemical and biological synthesis of caged phosphoproteins using the in vitro nonsense codon suppression methodology. Specifically, phosphoamino acid analogues of serine, threonine, and tyrosine with a single photocleavable o-nitrophenylethyl caging group were synthesized as the amino acyl tRNA adducts for insertion into full-length proteins. For this purpose, a novel phosphitylating agent was developed. The successful incorporation of these bulky and charged amino acids into the alpha-subunit of the nicotinic acetyl choline receptor (nAChR) and the vasodilator-stimulated phosphoprotein (VASP) using an in vitro translation system is reported.  相似文献   
34.
35.
Production of single mesons and opposite side pairs of mesons in hadron-nucleus and nucleusnucleus collisions are calculated in the framework of the QCD parton model, with the assumption that quarks and gluons undergo multiple scattering in the nucleus. A comparison with all available data is made. It is also shown that the anomalous nuclear enhancement, especially its dependence on the flavour, can be quantitatively described within the model. Furthermore, we predict no enhancement for symmetric pairs as it seems to be indicated by the data. Predictions for largep T production in α?α scattering at ISR are made.  相似文献   
36.
The problem of point excitation at a T-intersection of two perpendicular plates is studied in order to establish expressions for the point mobility. It is found that the theory for point excitation of the free surface of a semi-infinite elastic solid is applicable in the frequency range associated with structure-borne sound transmission. From this theory the mobility for an infinite system is derived. Based on this model and on an experimental investigation an estimation procedure for the point mobility in the finite dimension case is developed. The agreement with measurements performed in situ is quite acceptable. Both the theoretical and the experimental investigations reveal that the real part of this mobility is small, although it is larger in the experimental results. This indicates that other components of excitation are difficult to eliminate and may contribute to the power input in practice. Because of the small real part of the mobility it is advantageous with respect to the reduction of structure-borne sound power transmission to locate the contact points between a source and the receiver at such intersections. Corrections are deduced for the measured magnitude of the mobility for the case when separate force and motion transducers are used.  相似文献   
37.
We provide a sorting algorithm, Adaptive Heapsort, that optimally adapts to several known, and new, measures of presortedness. The algorithm is motivated by a new measure, called Osc, which intuitively tells the oscillation within the input sequence. We show that Osc generalizes a number of measures appearing in the literature. Moreover, it has an interesting application in the sweepline technique in computational geometry.  相似文献   
38.
We study quantum coherence in a semiconductor charge qubit formed from a GaAs double quantum dot containing a single electron. Voltage pulses are applied to depletion gates to drive qubit rotations and noninvasive state readout is achieved using a quantum point contact charge detector. We measure a maximum coherence time of ~7 ns at the charge degeneracy point, where the qubit level splitting is first-order insensitive to gate voltage fluctuations. We compare measurements of the coherence time as a function of detuning with numerical simulations and predictions from a 1/f noise model.  相似文献   
39.
40.
In this paper a new approach for simultaneous 2D velocity and temperature measurements using phosphoric particles is presented. The phosphoric particles respond to the temperature changes in the flow while acting as tracers for velocity mapping. The temperature sensitive particles were seeded into a heated flow and were excited by a pulsed UV laser. The subsequent red shifted emission was detected and analyzed to infer temperature using calibration procedures for lifetime and emission spectra against temperature. The diameter of the temperature sensitive particles, usually in the range of 1–10 μm, makes them useful for velocity measurements using particle image velocimetry (PIV). As such, simultaneous measurement of temperature and flow velocity of a gaseous flow were performed and presented. PACS  42.62.-b; 47.80.Cb; 47.80.Fg  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