全文获取类型
收费全文 | 1162篇 |
免费 | 41篇 |
国内免费 | 1篇 |
专业分类
化学 | 687篇 |
晶体学 | 7篇 |
力学 | 43篇 |
数学 | 88篇 |
物理学 | 379篇 |
出版年
2023年 | 11篇 |
2022年 | 10篇 |
2021年 | 19篇 |
2020年 | 17篇 |
2019年 | 27篇 |
2018年 | 13篇 |
2017年 | 20篇 |
2016年 | 38篇 |
2015年 | 32篇 |
2014年 | 31篇 |
2013年 | 74篇 |
2012年 | 58篇 |
2011年 | 82篇 |
2010年 | 47篇 |
2009年 | 34篇 |
2008年 | 55篇 |
2007年 | 44篇 |
2006年 | 53篇 |
2005年 | 40篇 |
2004年 | 33篇 |
2003年 | 30篇 |
2002年 | 28篇 |
2001年 | 28篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 19篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 15篇 |
1983年 | 15篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1975年 | 10篇 |
1973年 | 6篇 |
1971年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有1204条查询结果,搜索用时 234 毫秒
141.
142.
143.
Basu S 《Current protein & peptide science》2011,12(1):3-11
Cell motility is a very critical phenomenon that plays an important role in the development of eukaryotic organisms. One of the well studied cell motility phenomena is chemotaxis, which is described as a directional movement of cell in response to changes in external chemotactic gradient. Numerous studies conducted both in unicellular organism and in mammalian cells have demonstrated the importance of phosphatidylionositol-3 kinase (PI3K) in this process. In addition, it is now well established that although PI3K plays an activation role in chemotaxis, the role of phosphatases is also critical to maintain this dynamic cyclical process. Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase that is a key player in regulating PI3K signaling. PP2A is abundantly and ubiquitously expressed and has been highly conserved during the evolution of eukaryotes. PP2A is composed of three protein subunits, A, B, and C. Subunit 'A' is a 60-65 kDa structural component, 'C' is a 36-38 kDa catalytic subunit, and 'B' is a 54-130 kDa regulatory subunit. The core complex of PP2A is comprised of the A and C subunits, which are tightly associated and this dimeric core complexes with the regulatory B subunit. The B subunit determines the substrate specificity as well as the spatial and temporal functions of PP2A. PP2A plays an important role in regulating multiple signal transduction pathways, including cell-cycle regulation, cell-growth and development, cytoskeleton dynamics, and cell motility. This review focuses on the role of PP2A in regulating motility of normal and transformed cells. 相似文献
144.
We consider three dimensional finite element computations of thermoelastic damping ratios of arbitrary bodies using Zener’s
approach. In our small-damping formulation, unlike existing fully coupled formulations, the calculation is split into three
smaller parts. Of these, the first sub-calculation involves routine undamped modal analysis using ANSYS. The second sub-calculation
takes the mode shape, and solves on the same mesh a periodic heat conduction problem. Finally, the damping coefficient is
a volume integral, evaluated elementwise. In the only other decoupled three dimensional computation of thermoelastic damping
reported in the literature, the heat conduction problem is solved much less efficiently, using a modal expansion. We provide
numerical examples using some beam-like geometries, for which Zener’s and similar formulas are valid. Among these we examine
tapered beams, including the limiting case of a sharp tip. The latter’s higher-mode damping ratios dramatically exceed those
of a comparable uniform beam. 相似文献
145.
Nonlinear Dynamics - We consider the theoretical maximum extractable average power from an energy harvesting device attached to a vibrating table which provides a unidirectional displacement... 相似文献
146.
A. Chatterjee B. K. Chakrabarti 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(3):399-404
We study here numerically the behavior of an ideal gas like model of markets having
only one non-consumable commodity. We investigate the behavior of the
steady-state distributions of money, commodity and total wealth,
as the dynamics of trading or exchange of money and commodity proceeds,
with local (in time) fluctuations in the price of the commodity.
These distributions are studied in markets with agents having uniform and
random saving factors. The self-organizing features in money distribution
are similar to the cases without any commodity (or with consumable
commodities), while the commodity distribution shows an exponential decay.
The wealth distribution shows interesting behavior: gamma like
distribution for uniform saving propensity and has the same power-law tail,
as that of the money distribution, for
a market with agents having random saving propensity. 相似文献
147.
S Kailas A Navin A Chatterjee P Singh A Saxena D M Nadkarni D C Biswas R K Choudhury S S Kapoor 《Pramana》1993,41(4):339-344
The measurements of fission fragment angular distributions for the system19F+232Th have been extended to the sub-barrier energies of 89.3, 91.5 and 93.6 MeV. The measured anisotropies, within errors are
nearly the same over this energy region. However, the deviation of the experimental values of anisotropies from that of standard
statistical model predictions increases as the bombarding energy is lowered. 相似文献
148.
J. M. Chatterjee M. Sarkar S. Roy K. Weidenbrü 《Radiation Physics and Chemistry》2002,64(5-6):369-372
Samples of the raw input material and industrial wastes collected at different processing stages of lead smelting units have been analyzed using the synchrotron induced X-ray fluorescence method to detect and estimate the presence of heavy metals. Heavy metals such as Sb, Cd, Sn, Pb are found to be present in significant amounts. 相似文献
149.
150.
A configuration of reversal shear interferometer suitable for measurement of spatial coherence of high average power, large cross-section laser beam has been discussed. Ghost-less beam splitters in which unwanted multiple reflections from the surfaces have been suppressed by total internal reflection are used for beam splitting and re-combination. Advantages and drawbacks of this configuration have been discussed. 相似文献