全文获取类型
收费全文 | 14607篇 |
免费 | 2889篇 |
国内免费 | 3240篇 |
专业分类
化学 | 11129篇 |
晶体学 | 381篇 |
力学 | 1050篇 |
综合类 | 252篇 |
数学 | 1908篇 |
物理学 | 6016篇 |
出版年
2024年 | 39篇 |
2023年 | 207篇 |
2022年 | 463篇 |
2021年 | 502篇 |
2020年 | 547篇 |
2019年 | 604篇 |
2018年 | 528篇 |
2017年 | 536篇 |
2016年 | 709篇 |
2015年 | 840篇 |
2014年 | 906篇 |
2013年 | 1143篇 |
2012年 | 1284篇 |
2011年 | 1286篇 |
2010年 | 1132篇 |
2009年 | 1151篇 |
2008年 | 1154篇 |
2007年 | 1016篇 |
2006年 | 884篇 |
2005年 | 821篇 |
2004年 | 692篇 |
2003年 | 611篇 |
2002年 | 676篇 |
2001年 | 615篇 |
2000年 | 486篇 |
1999年 | 361篇 |
1998年 | 240篇 |
1997年 | 175篇 |
1996年 | 176篇 |
1995年 | 144篇 |
1994年 | 125篇 |
1993年 | 106篇 |
1992年 | 88篇 |
1991年 | 83篇 |
1990年 | 71篇 |
1989年 | 58篇 |
1988年 | 44篇 |
1987年 | 43篇 |
1986年 | 27篇 |
1985年 | 26篇 |
1984年 | 28篇 |
1983年 | 24篇 |
1982年 | 11篇 |
1981年 | 18篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1978年 | 7篇 |
1976年 | 4篇 |
1974年 | 6篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Let p ∈ [1, ∞), q ∈ [1, ∞), α∈ R, and s be a non-negative integer. Inspired by the space JNp introduced by John and Nirenberg(1961) and the space B introduced by Bourgain et al.(2015), we introduce a special John-Nirenberg-Campanato space JNcon(p,q,s) over Rn or a given cube of R;with finite side length via congruent subcubes, which are of some amalgam features. The limit space of such spaces as p →∞ is just the Campanato space which coincides with the space BMO(the space of functions with bounded mean oscillations)when α = 0. Moreover, a vanishing subspace of this new space is introduced, and its equivalent characterization is established as well, which is a counterpart of the known characterization for the classical space VMO(the space of functions with vanishing mean oscillations) over Rn or a given cube of Rn with finite side length.Furthermore, some VMO-H1-BMO-type results for this new space are also obtained, which are based on the aforementioned vanishing subspaces and the Hardy-type space defined via congruent cubes in this article. The geometrical properties of both the Euclidean space via its dyadic system and congruent cubes play a key role in the proofs of all these results. 相似文献
2.
3.
4.
5.
7.
8.
The stable phase equilibria of quaternary systems LiBr-NaBr-MgBr2-H2O and LiBr-KBr-MgBr2-H2O at 298.15 K were studied by both experimental measurement(isothermal solution saturation method) and theoretical prediction(Pitzer model). The solubilities of the saturated solution have been determined experimentally and two stable phase diagrams and relevant water diagrams of the two quaternary systems were obtained. Results show that quaternary system LiBr-NaBr-MgBr2-H2O is hydrate II type as NaBr and NaBr·2H2O coexistence. Its phase diagram consists of only one invariant point, four univariant curves, and five crystallization fields. The quaternary system LiBr-KBr-MgBr2-H2O is a complex type as the double salt KBr·MgBr2·6H2O formed. In addition to this double salt, the three single salts LiBr·2H2O, KBr and MgBr2·6H2O also crystallize. In this paper, the solubilities of phase equilibria in above quaternary systems were also calculated by the Pitzer's electrolyte solution model. All the needed parameters can be obtained from the literature or be fitted by experimental data. On the Basis of the experimental and calculated results, the phase diagram of the quaternary system was plotted for comparison. It shows that the calculation results are consistent with the experimental ones. 相似文献
9.
HIRFL–CSR加速器中束流与真空中剩余气体的碰撞损失 总被引:1,自引:1,他引:0
研究了重离子加速器中束流与真空中剩余气体的碰撞损失过程和碰撞截面,在依据大量实验数据的基础上,提出了一组计算离子一原子的电荷交换截面的经验公式.以兰州重离子加速器HDRFL及冷却储存环CSR为例,给出了依据碰撞截面的公式计算束流在加速器真空中的传输效率的方法,并计算了在不同真空度下HIRFL的ECR源轴向注入束运线、注入器SFC、前束运线、主加速器SSC和后束运线等不同加速阶段及CSR的传输效率,并提出合理的真空度要求.HIRFL的真空分布测量和束流的损失测量证明了该计算方法的可靠性. 相似文献
10.
本文在一类 Lp位势V(x)下建立了广义Schrodinger算子H=(-Δ)m+V(x)在C∞0(Rn)上的本质自伴性,给出了H的本质谱的分布. 相似文献