全文获取类型
收费全文 | 237595篇 |
免费 | 3042篇 |
国内免费 | 1432篇 |
专业分类
化学 | 110529篇 |
晶体学 | 3276篇 |
力学 | 12603篇 |
综合类 | 51篇 |
数学 | 38208篇 |
物理学 | 77402篇 |
出版年
2020年 | 1102篇 |
2018年 | 10468篇 |
2017年 | 11322篇 |
2016年 | 6016篇 |
2015年 | 2353篇 |
2014年 | 1958篇 |
2013年 | 5526篇 |
2012年 | 8770篇 |
2011年 | 18514篇 |
2010年 | 10981篇 |
2009年 | 10806篇 |
2008年 | 15740篇 |
2007年 | 19604篇 |
2006年 | 4698篇 |
2005年 | 11748篇 |
2004年 | 7466篇 |
2003年 | 6997篇 |
2002年 | 4824篇 |
2001年 | 3897篇 |
2000年 | 3159篇 |
1999年 | 2411篇 |
1998年 | 2058篇 |
1997年 | 2013篇 |
1996年 | 2114篇 |
1995年 | 1984篇 |
1994年 | 1735篇 |
1993年 | 1678篇 |
1992年 | 1885篇 |
1991年 | 1878篇 |
1990年 | 1797篇 |
1989年 | 1806篇 |
1988年 | 1742篇 |
1987年 | 1716篇 |
1986年 | 1627篇 |
1985年 | 2196篇 |
1984年 | 2333篇 |
1983年 | 1936篇 |
1982年 | 2244篇 |
1981年 | 2076篇 |
1980年 | 2108篇 |
1979年 | 2134篇 |
1978年 | 2258篇 |
1977年 | 2076篇 |
1976年 | 2142篇 |
1975年 | 2074篇 |
1974年 | 1908篇 |
1973年 | 2174篇 |
1972年 | 1304篇 |
1968年 | 1150篇 |
1967年 | 1131篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
61.
Gas-phase 21Ne nuclear magnetic resonance spectra were measured at the natural abundance of 21Ne isotope for samples consisting of pressurized neon up to 60 bar at room temperature and applying the magnetic field of the strength B0 = 11.7574 T. It showed that the nuclear magnetic resonance frequency is linearly dependent on the density of gaseous neon. The resonance frequency was extrapolated to the zero-density point, and it permitted the determination of the 21Ne nuclear magnetic moment, μ(21Ne) = 0.6617774(10) μN. The present value of μ(21Ne) is not influenced by the bulk magnetic susceptibility of neon and interactions between neon atoms; therefore, it is more precise and reliable than the previous result obtained for μ(21Ne). 相似文献
62.
Understanding defect production in an hcp Zr crystal upon irradiation:An energy landscape perspective 下载免费PDF全文
Primary radiation damage in hcp Zr,including both defect production in a single collision cascade and damage buildup through cascade overlap,is investigated using molecular dynamics(MD)simulations from a potential energy landscape(PEL)perspective.It is found that the material’s response to an energetic particle can be understood as a trajectory in the PEL comprising a fast uphill journey and a slow downhill one.High-temperature-induced damage reduction and the difference in the radiation tolerance between metals and semiconductors can be both qualitatively explained by the dynamics of the trajectory associated with the topographic features of the system’s PEL.Additionally,by comparing irradiation and heating under a nearly identical condition,we find that large atomic displacements stemming from the extreme locality of the energy deposition in irradiation events are the key factor leading to radiation damage in a solid.Finally,we discuss the advantages of the PEL perspective and suggest that a combination of the PEL and the traditional crystallographic methods may provide more insights in future work. 相似文献
63.
64.
65.
66.
Here, we report a new strategy for rapid synthesis of branched peptide by side-chain hydrazide ligation at Asn. The hydrazide was converted to thioester at Asn side chain by NaNO2 and thiol reagent, and sequential ligation with an N-terminus Cys-peptide efficiently afforded the branched peptide. A branched cyclic peptide was successfully synthesized by side-chain ligation with a two-Cys-peptide and formation of a disulfide bond. This approach provides a new way for expeditious synthesis of branched peptides and facilitates the design of neopeptides as functional bio-mimics. 相似文献
67.
68.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献
69.
N. I. Golovina G. N. Nechiporenko G. G. Nemtsev G. P. Dolganova V. P. Roshchupkin D. B. Lempert G. B. Manelis 《Russian Journal of Applied Chemistry》2007,80(1):24-30
Methods for phase stabilization of ammonium nitrate were sought for in order to considerably expand the application area of this oxidizing agent in various-purpose self-combustible formulations, including that in a new generation of gas-generating formulations for automobile air bags. New methods for stabilization of ammonium nitrate were studied and, in particular, a search was made for organic compounds that can stabilize ammonium nitrate even at their low content. The mechanism of phase state stabilization of ammonium nitrate by compounds of this kind was examined. 相似文献
70.
Yu. V. Pokonova 《Russian Journal of Applied Chemistry》2007,80(12):2163-2164
Kinetic, sorption and selectivity properties of commercial adsorbents are improved by adding petroleum residues (tar asphaltene concentrates) 13% of whole mass. Obtained adsorbents can be used for selective extraction of nobel metals from multicomponent polymetallic solutions of heavy metals and fro sewages purification for removing arsenic. 相似文献