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   37篇
  免费   0篇
化学   11篇
力学   1篇
数学   7篇
物理学   18篇
  2019年   2篇
  2018年   1篇
  2016年   1篇
  2015年   1篇
  2012年   1篇
  2011年   3篇
  2009年   3篇
  2008年   1篇
  2007年   4篇
  2006年   1篇
  2004年   2篇
  2001年   1篇
  2000年   1篇
  1996年   2篇
  1989年   2篇
  1987年   2篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1980年   2篇
  1975年   1篇
  1974年   1篇
排序方式: 共有37条查询结果,搜索用时 31 毫秒
11.
The ergodic propriety of a room has strong effects on its reverberation. If the room is ergodic, the reverberation can be broken up in two steps: a deterministic process followed by a stochastic one. The late reverberation can be then modeled by a reverberation algorithm instead of more computationally consuming methods. In this study, the free path temporal distribution obtained by ray-tracing is used as an indicator of the room's mixing: the energetic average of the path lengths is computed at each time step. Ergodic rooms are thus characterized by rapidly convergent distributions. The free path value becomes independent of time. On the other hand, path selection mechanism and orbits are observed in non-ergodic rooms. The transition time from the deterministic process to the stochastic one is also studied through the evaluation of the room's time constant. It is shown that its value depends only on the mean free path and the boundaries scattering value. An empirical expression is obtained which agrees well with simulations carried out in a concert hall. This transition time from a deterministic model to a stochastic one can be used to speed up the acoustical predictions and auralizations in ergodic rooms.  相似文献   
12.
This is a continuation of our earlier investigation (Gurtuet al 1974Phys. Lett. 50 B 391) on multiparticle production in proton-nucleus collisions based on an exposure of emulsion stack to 200 GeV/c beam at the NAL. It is found that the ratioR em = 〈n s〉/〈n ch〉, where 〈n ch〉 is the charged particle multiplicity in pp-collisions, increases slowly from about 1 at 10 GeV/c to 1·6 at 68 GeV/c and attains a constant value of 1·71 ± 0·04 in the region 200 to 8000 GeV/c. Furthermore,R em = 1·71 implies an effectiveA-dependence ofR A =A 0.18,i.e., a very weak dependence. Predictions ofR em on various models are discussed and compared with the emulsion data. Data seem to favour models of hadron-nucleon collisions in which production of particles takes place through adouble step mechanism,e.g., diffractive excitation, hydrodynamical and energy flux cascade as opposed to models which envisage instantaneous production.  相似文献   
13.
This paper reviews immunoaffinity CE procedures developed since 1998 for drug, hormone, and disease marker analyses of body fluids and tissues. Immunoaffinity CE and related techniques are described. Examples of clinical applications are included.  相似文献   
14.
Amundsen LK  Sirén H 《Electrophoresis》2007,28(20):3737-3744
ACE is a popular technique for evaluating association constants between drugs and proteins. However, ACE has not previously been applied to study the association between electrically neutral biomolecules and plasma proteins. We studied the affinity between human and bovine serum albumins (HSA and BSA, respectively) and three neutral endogenous steroid hormones (testosterone, epitestosterone and androstenedione) and two synthetic analogues (methyltestosterone and fluoxymesterone) by applying the partial-filling technique in ACE (PF-ACE). From the endocrinological point of view, the distribution of endogenous steroids among plasma components is of great interest. Strong interactions with albumins suppress the biological activity of steroids. Notable differences in the association constants were observed. In the case of the endogenous steroids, the interactions between testosterone and the albumins were strongest, and those between androstenedione and the albumins were substantially weaker. The association constants, K(b), for testosterone, epitestosterone and androstenedione and HSA at 37 degrees C were 32 100 +/- 3600, 21 600 +/- 1500 and 13 300 +/- 1300 M(-1), respectively, while the corresponding values for the steroids and BSA were 18 800 +/- 1500, 14 000 +/- 400 and 7800 +/- 900 M(-1). Methyltestosterone was bound even more strongly than testosterone, while fluoxymesterone was only weakly bound by the albumins. Finally, the steroids were separated by PF-ACE with HSA and BSA used as resolving components.  相似文献   
15.
We present a high-throughput roll-to-roll (R2R) manufacturing process for foil-based polymethyl methacrylate (PMMA) chips of excellent optical quality. These disposable, R2R hot embossed microfluidic chips are used for the identification of the antibiotic resistance gene mecA in Staphylococcus epidermidis. R2R hot embossing is an emerging manufacturing technology for polymer microfluidic devices. It is based on continuous feeding of a thermoplastic foil through a pressurized area between a heated embossing cylinder and a blank counter cylinder. Although mass fabrication of foil-based microfluidic chips and their use for biological applications were foreseen already some years ago, no such studies have been published previously.  相似文献   
16.
Most real-world networks considered in the literature have a modular structure. Analysis of these real-world networks often are performed under the assumption that there is only one type of node. However, social and biochemical systems are often bipartite networks, meaning that there are two exclusive sets of nodes, and that edges run exclusively between nodes belonging to different sets. Here we address the issue of module detection in bipartite networks by comparing the performance of two classes of group identification methods – modularity maximization and clique percolation – on an ensemble of modular random bipartite networks. We find that the modularity maximization methods are able to reliably detect the modular bipartite structure, and that, under some conditions, the simulated annealing method outperforms the spectral decomposition method. We also find that the clique percolation methods are not capable of reliably detecting the modular bipartite structure of the bipartite model networks considered.  相似文献   
17.
18.
Spontaneous and explicit chiral symmetry breaking is analyzed in Coulomb gauge QCD at finite temperatures, using an instantaneous approximation for the quark interaction and incorporating confinement through a running coupling constant. The thermodynamics of the quarks is treated approximatively by assuming that the momentum-dependent constituent quark mass sets the scale for thermodynamic fluctuations of colour singlet excitations. We investigate the class of a temperature independent and a temperature dependent interaction between quarks. In the chiral limit both temperature independent and a smooth temperature dependent interaction yields a second order chiral phase transition with critical exponents close to the values for a BCS super-conductor. For explicit chiral symmetry breaking we find a nearly constant pion mass below the transition temperature, but a strongly overdamped mode above. For a first order deconfining transition in the gluonic sector also the quark sector shows a first order chiral phase transition. The relevance of our results for relativistic heavy ion collisions is briefly discussed.  相似文献   
19.
The electromagnetic pion form factor and radius is calculated in a model which can be derived from Coulomb gauge QCD in an instantaneous approximation discussed recently. The results agree well with experimental data without further adjustment of parameters. They are also compared to results obtained in the Nambu-Jona-Lasinio and in the Vector Meson Dominance model.  相似文献   
20.
Exposure-effect relationships between the level of road traffic noise at the most exposed side of a dwelling's façade and the residents' reactions to road traffic noise have been estimated. The relationships are based on five Norwegian socio-acoustic studies featuring 18 study areas from two cities and a total of near 4000 respondents. The survey questionnaires distinguish between noise annoyance experienced right outside the apartment and when indoors. Exposure-effect relationships for all degrees of annoyance are estimated simultaneously from ordinal logit models. These predict road traffic noise annoyance when right outside the apartment and when indoors, respectively, as a function of the road traffic noise level outside the most exposed façade. Separate analyses indicate that Norwegians react stronger to road traffic noise than results from a recent compilation of socio-acoustic surveys would lead one to believe. People having inferior single glazing windows report higher indoor annoyance.  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