全文获取类型
收费全文 | 753篇 |
免费 | 23篇 |
国内免费 | 2篇 |
专业分类
化学 | 415篇 |
晶体学 | 24篇 |
力学 | 12篇 |
数学 | 80篇 |
物理学 | 247篇 |
出版年
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 27篇 |
2019年 | 22篇 |
2018年 | 18篇 |
2017年 | 22篇 |
2016年 | 35篇 |
2015年 | 17篇 |
2014年 | 26篇 |
2013年 | 48篇 |
2012年 | 41篇 |
2011年 | 54篇 |
2010年 | 31篇 |
2009年 | 26篇 |
2008年 | 20篇 |
2007年 | 17篇 |
2006年 | 20篇 |
2005年 | 28篇 |
2004年 | 21篇 |
2003年 | 8篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1997年 | 7篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 9篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 12篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1971年 | 4篇 |
1970年 | 5篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1967年 | 7篇 |
排序方式: 共有778条查询结果,搜索用时 15 毫秒
1.
Gopalakrishna K. Bhat 《Optics and Lasers in Engineering》1997,26(1):43-58
An electro-optic holographic technique (also called electronic speckle pattern interferometry or TV holography) for the measurement of displacements and strains on three-dimensional object surfaces is presented. The three components of the displacement vector, in a fixed coordinate system, are separated using four independent illumination beams. The interferometric phase for each illumination beam is extracted using the phase stepping technique. Displacements in the fixed coordinate system are projected on to the object surface using the tensor transformation law. Equations for the computation of surface strains using the projected displacements and the surface geometry are developed. The technique is applied for the measurement of strains on the surface of a cylindrical vessel subjected to internal pressure. 相似文献
2.
E. Kapon M. Walther J. Christen M. Grundmann C. Caneau D.M. Hwang E. Colas R. Bhat G.H. Song D. Bimberg 《Superlattices and Microstructures》1992,12(4)
Quantum wire (QWR) heterostructures suitable for optoelectronic applications should meet a number of requirements, including defect free interfaces, large subband separation, long carrier lifetime, efficient carrier capture. The structural and opticl properties of GaAs/AlGaAs and InGaAs/GaAs quantum wire (QWR) heterostructures grown by organometallic chemical vapor deposition on nonplanr substrates, which satisfy many of these criteria, are described. These crescent-shaped QWRs are formed in situ during epitaxial growth resulting in virtually defect free interfaces. Effective wire widths as small as 10nm have been achieved, corresponding to electron subband separations greater than KBT at room temperature. The enhanced density of states at the QWR subbands manifests itself in higher optical absorption and emission as visualized in photoluminescence (PL), PL excitation, amplified spontaneous emission and lasing spectra of these structures. Effective carrier capture into the wires via connected quantum well regions, which is important for enhancing the otherwise extremely small capture cross section of these wires, has also been observed. Room temperature operation of GaAs/AlGaAs and strained InGaAs/GaAs QWR lasers with threshold currents as low as 0.6mA has been demonstrated. 相似文献
3.
4.
Spin-flip (paramagnetic) scattering and neutron depolarization studies were performed on Ce2Fe17 in its paramagnetic phase on the Dhruva neutron polarization analysis spectrometer. The absence of normalQ dependence of the scattered spin flip intensity shows that Ce2Fe17 is not a normal paramagnetic and there exist superparamagnetic clusters of sufficiently large dimensions (~100Å). The observed neutron depolarization gives an indication of the dynamics of these Ce2Fe17 superparamagnetic clusters. 相似文献
5.
Ashwani K. Padthe Nalin A. Chaturvedi Dennis S. Bernstein Sanjay P. Bhat Anthony M. Waas 《International Journal of Non》2008,43(4):277-291
We study a linearly damped preloaded two-bar linkage that exhibits hysteresis due to the presence of multiple attracting equilibria. The dynamics at the unstable equilibrium, through which a snap-through buckle occurs, are not linearizable due to a solution-dependent singularity. We stabilize the unstable equilibrium using two distinct non-linear controllers. The feedback-linearization controller requires knowledge of the linkage parameters, whereas the robust version of the intrinsic non-linear proportional-derivative controller requires only an upper bound on the stiffness. 相似文献
6.
Vasanthakumar N. Bhat 《The Journal of the Operational Research Society》1994,45(3):345-353
The switched Poisson process (SPP), also known as the doubly stochastic Poisson process, has been widely used in the modelling of point processes whose rates vary subject to some random mechanism. The class of SPP includes a wide range of both renewal and non-renewal processes with squared coefficients of variation being larger than one. In this paper, we survey various approaches to approximate a non-renewal process by a renewal process. We derive the expressions for the first two moments of the inter-renewal time of a renewal process that approximates the SPP. We illustrate the quality of these approximations with numerical results in queueing applications. We believe that our approximations have potential applications in areas such as reliability, inventory control, telecommunications and maintenance. 相似文献
7.
Ammar R Ball RC Banerjee S Bhat PC Bosetti P Bromberg C Canough GE Coffin T Dershem TO Dixon RL Fenker HC Ganguli SN Gensch U Girtler P Goshaw AT Grard F Gurtu A Hamilton C Henri VP Hernandez JJ Hrubec J Iori M Jones LW Kuhn D Knauss D Leedom ID Legros P Lemonne J Leutz H Liu X Malhotra PK Marraffino JM Mendez GE Miller R Naumann T Nguyen A Nowak H Pilette P Poirier J Poppleton A Raghavan R Rasner K Reucroft S Robertson WJ Roe BP Roth A Senko M Struczinski W Subramanian A Touboul MC Vonck B 《Physical review letters》1988,61(19):2185-2188
8.
9.
10.
Viscometric method has been used to study the interaction between the weak interacting systems such as benzene-CCl4-cyclohexane, toluene-CCl4-cyclohexane ando- xylene-CCl4-cyclohexane. The equilibrium constants and other thermodynamic parameters have been reported and compared with literature
data. 相似文献