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111.
In modern telephone exchanges, subscriber lines are usually connected to the so-called subscriber line modules. These modules serve both incoming and outgoing traffic. An important difference between these two types of calls lies in the fact that in the case of blocking due to all channels busy in the module, outgoing calls can be queued whereas incoming calls get busy signal and must be re-initiated in order to establish the required connection. The corresponding queueing model was discussed recently by Lederman, but only the model with losses has been studied analytically. In the present contribution, we study the model which takes into account subscriber retrials and investigate some of its properties such as existence of stationary regime, derive explicit formulas for the system characteristics, limit theorems for systems under high repetition intensity of blocked calls and limit theorems for systems under heavy traffic. 相似文献
112.
Y. Marandet H. Capes L. Godbert-Mouret M. Koubiti J. Rosato R. Stamm 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(2):247-260
In this work we investigate the influence of low
frequency turbulence on Doppler spectral line shapes in magnetized
plasmas. Low frequency refers here to fluctuations whose typical
time scale is much larger than those characterizing the atomic
processes, such as radiative decay, collisions and charge exchange.
This ordering is in particular relevant for drift wave turbulence,
ubiquitous in edge plasmas of fusion devices. Turbulent fluctuations
are found to affect line shapes through both the spatial and time
averages introduced by the measurement process. The profile is
expressed in terms of the fluid fields describing the plasma.
Assuming the spectrometer acquisition time to be much larger than
the turbulent time scale, an ordering generally fulfilled in
experiments, allows to develop a statistical formalism. We proceed
by successively investigating the effects of density, fluid velocity
and temperature fluctuations on the Doppler profile of a spectral
line emitted by a charge exchange population of neutrals. Line
shapes, and especially line wings are found to be affected by ion
temperature or fluid velocity fluctuations, and can in some cases
exhibit a power-law behavior. These effects are shown to be
measurable with existing techniques, and their interpretation in
each particular case would rely on already existing tools. From a
fundamental point of view, this study gives some insights in the
appearance of non-Boltzmann statistics, such as Lévy statistics,
when dealing with averaged experimental data. 相似文献
113.
熔制了掺铒碲铌玻璃样品(100-X)TeO2-XNb2O5(X=5,10,15,20mol%),测试了其密度、折射率、转变温度、析晶温度、维氏机械强度、吸收光谱、荧光光谱、荧光寿命等参量。利用Judd-Ofelt和McCumber理论分别计算了铒离子强度参量Ωt(t=2,4,6)和受激发射截面σemi的大小,研究了掺铒碲铌玻璃样品光谱参量对Nb2O5成分的依赖性,并与典型的碲锌钠玻璃(75TeO2-20ZnO-5Na2O)在热学、机械强度、光谱性质和放大品行四个方面进行了比较. 相似文献
114.
利用Debye模型,研究了等离子体屏蔽效应对热等离子体中原子能级和振子强度的影响.通过在MCDF模型中引入等离子体屏蔽效应,计算了MnXXII-BrXXII等11个类Be离子在等离子体环境下2s2—[2s1/2,2p1/2]1和2s2—[2s1/2,2p3/2]1跃迁的能级和振子强度.计算结果表明,等离子体屏蔽效应使得类Be离子2s2—[2s1/2,2p1/2]1跃迁的激发能量增大,从而导致谱线蓝移现象;并且随着屏蔽效应的不断增强,蓝移的程度会逐渐加大.屏蔽效应对于2s2—[2s1/2,2p3/2]1跃迁的振子强度也有类似的影响.
关键词:
Debye
等离子体屏蔽
跃迁能级
振子强度 相似文献
115.
116.
利用激光干涉测速技术(VISAR)测量LY12铝合金在20—34 GPa冲击压力下经历加载-卸载和加载-再加载过程的样品/窗口界面粒子速度剖面,采用AC方法确定了具有较高精度的动态屈服强度值.实验结果和文献发表的数据具有较好的一致性.通过以平面焊接方式制作组合飞片,克服了组合飞片在气炮发射过程中可能发生分离的技术困难,使铝的动态屈服强度测量压力范围从22 GPa扩展到了34 GPa.同时,根据对不同实验条件下的加载-再加载过程的比较,对再加载弹性前驱波的形成机理进行了讨论,认为位错是形成该现象的主要原因. 相似文献
117.
在考虑组态相互作用的基础上,利用包含相对论修正的Hartree-Fock(HFR)理论对S8+-S13+离子的谱线波长及加权振子强度等有关原子参数进行了系统计算,并与最新的实验观测和其它理论计算结果进行了比较。计算结果表明:S8+-S11+的各个原子态在LS耦合下纯度很高,随着离化度的增大,S12+和S13+离子的部分原子态能级出现混合,组态相互作用逐渐增强。通过对实验结果的分析,识别出32条实验谱线,其中大多数谱线来自S8+-S13+离子的2s22pk-2s2pk+1和2s2pk+1-2s2pk+2(k=0,1,2,3,4)之间的跃迁,理论计算结果与实验谱线波长之间的绝对误差大多数都在实验的有效分辨力以内。 相似文献
118.
Gain coefficients have been calculated for transitions of singlet levels ns–np of orbital n=4 and n=5 in magnesium-like ions with atomic numbers Z=18, 19, 20, 21, 22 and 23. Population inversions for 4p and 5p levels in these ions were also calculated, via electron collisional excitation, for electron temperature range of 93–231 eV and electron density range of 1016–1017 cm−3. Under these plasma conditions, the maximum gain that occurred for 4s–4p transition was at electron temperature of 231 eV and electron density of 4×1017 cm−3. Scaling of the maximum gain coefficients with atomic number Z and the plasma parameters is also presented. 相似文献
119.
120.
Seung Hyun Sung William B. Farnham Heidi E. Burch Yefim Brun Kai Qi Thomas H. Epps 《Journal of Polymer Science.Polymer Physics》2019,57(24):1663-1672
We demonstrate the directional alignment of perpendicular‐lamellae domains in fluorinated three‐armed star block polymer (BP) thin films using solvent vapor annealing with shear stress. The control of orientation and alignment was accomplished without any substrate surface modification. Additionally, three‐armed star poly(methyl methacrylate‐block‐styrene) [PMMA‐PS] and poly(octafluoropentyl methacrylate‐block‐styrene) were compared to their linear analogues to examine the impact of fluorine content and star architecture on self‐assembled BP feature sizes and interdomain density profiles. X‐ray reflectometry results indicated that the star BP molecular architecture increased the effective polymer segregation strength and could possibly facilitate reduced polymer domain spacings, which are useful in next‐generation nanolithographic applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1663–1672 相似文献