全文获取类型
收费全文 | 13910篇 |
免费 | 252篇 |
国内免费 | 71篇 |
专业分类
化学 | 8299篇 |
晶体学 | 105篇 |
力学 | 574篇 |
数学 | 2283篇 |
物理学 | 2972篇 |
出版年
2021年 | 140篇 |
2020年 | 155篇 |
2019年 | 149篇 |
2018年 | 158篇 |
2017年 | 126篇 |
2016年 | 252篇 |
2015年 | 216篇 |
2014年 | 232篇 |
2013年 | 778篇 |
2012年 | 479篇 |
2011年 | 624篇 |
2010年 | 420篇 |
2009年 | 377篇 |
2008年 | 545篇 |
2007年 | 514篇 |
2006年 | 512篇 |
2005年 | 497篇 |
2004年 | 527篇 |
2003年 | 453篇 |
2002年 | 443篇 |
2001年 | 266篇 |
2000年 | 263篇 |
1999年 | 191篇 |
1998年 | 156篇 |
1997年 | 177篇 |
1996年 | 229篇 |
1995年 | 174篇 |
1994年 | 177篇 |
1993年 | 205篇 |
1992年 | 200篇 |
1991年 | 201篇 |
1990年 | 159篇 |
1989年 | 163篇 |
1988年 | 169篇 |
1987年 | 215篇 |
1986年 | 184篇 |
1985年 | 259篇 |
1984年 | 256篇 |
1983年 | 200篇 |
1982年 | 230篇 |
1981年 | 235篇 |
1980年 | 247篇 |
1979年 | 237篇 |
1978年 | 220篇 |
1977年 | 214篇 |
1976年 | 186篇 |
1975年 | 208篇 |
1974年 | 186篇 |
1973年 | 162篇 |
1972年 | 110篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
941.
Tetsuo Kanamoto Anagnostis E. Zachariades Roger S. Porter 《Journal of Polymer Science.Polymer Physics》1982,20(8):1485-1496
The aliphatic polyamides nylon 6 and 6,6 have been cold drawn by using the new concept of reversible plasticization with NH3. Two aspects were investigated: the effect of NH3 plasticization on the stress-strain behavior of nylon 6,6, and the extent of NH3 absorption as determined by x-ray analysis for the structurally simpler nylon 6. X-ray analysis shows that ammonia is absorbed preferentially by the amorphous phase and that the plasticization has a significant effect on the unit-cell orientation, the small-angle void scattering, and the interplanar spacings between sheets of hydrogen-bonded chains. The effect of plasticization was seen in the lower yield stress, the higher draw ratio (up to 8X) and tensile modulus (10 GPa) not attainable with unplasticized specimens. 相似文献
942.
The chemiluminescence, measured at 500 nm, allows nickel carbonyl to be measured in the range 1 ppb to several ppm in combustion gases. Interferences from iron pentacarbonyl and nitrogen monoxide are eliminated by optical and spatial discrimination and by choice of the pressure in the reaction chamber. 相似文献
943.
944.
945.
The fluoride capacity of the Dowex 1-X4 anion exchange resin was measured by radiometric and elemental analysis. The capacity
data obtained by the two methods showed good agreement. 相似文献
946.
A two-atom blocking model has been developed to analyze surface blocking patterns recently obtained in medium energy ion scattering experiments. In the model the mean square thermal vibration amplitude of a surface atom can be used as a fitting parameter in comparison with experimental results. Anisotropic surface vibrations have been taken into account by assuming a non-spherical Gaussian probability distribution for the thermal displacement of the surface atom. In addition, some analytical expressions have been derived for the effective nuber of target atoms contributing to the yield of ions backscattered into a blocking direction. 相似文献
947.
J.G. Wijmans S. Nakao J.W.A. Van Den Berg F.R. Troelstra C.A. Smolders 《Journal of membrane science》1985,22(1):117-135
The influence of concentration polarization on the permeate flux in the ultrafiltration of aqueous Dextran T70 solutions can be described by (i) the osmotic pressure model and (ii) the boundary layer resistance model. In the latter model the hydrodynamic resistance of the non-gelled boundary layer is computed using permeability data of the Dextran molecules obtained by sedimentation experiments. It is shown both in theory and experiment that the two models are equivalent. 相似文献
948.
949.
P. Van Beek 《European Journal of Operational Research》1981,6(2):236-238
950.
P.M. Heinen J.J. Engelen E.W. Kittel W.J. Metzger M.M. Schouten J.S.M. Vergeest R.T. Van De Walle B. Jongejans H. Voorthuis M. Cerrada R.J. Hemingway S.O. Holmgren M.J. Losty 《Nuclear Physics B》1977,122(3):443-463
A partial-wave analysis of the low-mass (π+π?p) system produced in the reaction K?p → K?(π+π?p) at 4.2 GeV/c incident momentum is performed in order to study the two (π+π?p) enhancements around 1500 and 1700 MeV. It is found that the low-mass (π+π?p) system can be described using the spin-parity states and only. In the 1500 MeV region contributions are observed from the wave decaying into p? and the wave decaying into Δ++π?; in the 1700 MeV region contributions are found from the wave decaying into Δ++π?, the wave decaying into p?, and the wave decaying into p?. 相似文献