全文获取类型
收费全文 | 6908篇 |
免费 | 619篇 |
国内免费 | 718篇 |
专业分类
化学 | 4333篇 |
晶体学 | 53篇 |
力学 | 479篇 |
综合类 | 29篇 |
数学 | 748篇 |
物理学 | 1764篇 |
无线电 | 839篇 |
出版年
2024年 | 12篇 |
2023年 | 85篇 |
2022年 | 133篇 |
2021年 | 167篇 |
2020年 | 203篇 |
2019年 | 175篇 |
2018年 | 156篇 |
2017年 | 157篇 |
2016年 | 229篇 |
2015年 | 242篇 |
2014年 | 308篇 |
2013年 | 603篇 |
2012年 | 411篇 |
2011年 | 545篇 |
2010年 | 396篇 |
2009年 | 473篇 |
2008年 | 447篇 |
2007年 | 425篇 |
2006年 | 440篇 |
2005年 | 362篇 |
2004年 | 325篇 |
2003年 | 315篇 |
2002年 | 243篇 |
2001年 | 154篇 |
2000年 | 169篇 |
1999年 | 144篇 |
1998年 | 142篇 |
1997年 | 108篇 |
1996年 | 106篇 |
1995年 | 89篇 |
1994年 | 72篇 |
1993年 | 63篇 |
1992年 | 60篇 |
1991年 | 47篇 |
1990年 | 33篇 |
1989年 | 38篇 |
1988年 | 34篇 |
1987年 | 17篇 |
1986年 | 26篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 5篇 |
1982年 | 13篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 3篇 |
排序方式: 共有8245条查询结果,搜索用时 801 毫秒
31.
报道Ar^q Ne(q=8,9,11,12)碰撞体系中多电子转移过程,得到了多组实验测量电荷交换截面数据,讨论入射离子电荷交换截面、反冲离子产生截面与入射离子电荷态、能量以及散射离子电荷态的关系,并且将实验结果与Ar^q Ar碰撞体系进行对比研究。在修正分子库仑过垒模型的基础上,对实验现象做了合理的解释。 相似文献
32.
A new method based on anion exchange resin separation and graphite furnace atomic absorption spectrometry (GFAAS) detection
is proposed for the determination of inorganic tin species. The result showed that Sn(IV) was quantitatively retained on the
resin when [HCl] = 9.0 mol · L−1, but Sn(II) could not be adsorbed on the resin under the same condition. Thus, a separation of Sn(II) and Sn(IV) has been
realized. When the concentration of NaOH solution was between 2.0–7.0 mol · L−1, Sn(IV) that adsorbed on the resin could be eluated from the resin completely. Meanwhile, under the atmosphere and the nitrogen
states, the translation between Sn(II) and Sn(IV) was investigated. Under the optimal conditions, the detection limit of Sn(IV)
is 0.40 μg · L−1 with RSD of 2.3% (n = 5, c = 2.0 μg · L−1). The proposed method was applied to the speciation analysis of tin in different water samples and the recovery of total
Sn was in the range of 98.7–101.7%. In order to verify the accuracy of the method, a certified reference water sample was
analyzed and the results obtained were in good agreement with the certified value. 相似文献
33.
34.
35.
In this article we use classical formulas involving the K–Bessel function in two variables to express the Poisson kernel on a Riemannian manifold in terms of the heat kernel. We then use the small time asymptotics of the heat kernel on certain Riemannian manifolds to obtain a meromorphic continuation of the associated Poisson kernel to all values of complex time with identifiable singularities. This result reproves in a different setting by different means a well–known theorem due to Duistermaat and Guillemin [DG 75]. Also, we develop analytic expressions for the heat kernel beyond asymptotic expansions. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
36.
Werner WinterGünther W.H Höhne 《Thermochimica Acta》2003,403(1):43-53
A method for measuring heat capacities of small samples using a chip-calorimeter and a heat pulse technique is described. The theoretical background to calculate the heat transport properties and the heat capacity of the sample from the pulse response function is given. Problems and potentials of the method are discussed. An example is given. 相似文献
37.
Qingrong Zheng Gang Su Jian Wang Hong Guo 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(2):233-238
We report a theoretical analysis of the phonon thermal conductance, κ(T), for single wall carbon nanotubes (SWCN). In a range of low temperatues up to 100 K, κ(T) of perfect SWCN is found to increase with temperature, approximately, in a parabolic fashion. This is qualitatively consistent
with recent experimental measurements where the tube-tube interactions are negligibly weak. When the carbon-carbon bond length
is slightly varied, κ(T) is found to be qualitatively unaltered which implies that the anharmonic effect does not change the qualitative behavior
of κ(T).
Received 12 June 2001 相似文献
38.
39.
40.