全文获取类型
收费全文 | 7593篇 |
免费 | 1142篇 |
国内免费 | 986篇 |
专业分类
化学 | 5537篇 |
晶体学 | 45篇 |
力学 | 481篇 |
综合类 | 60篇 |
数学 | 828篇 |
物理学 | 2770篇 |
出版年
2024年 | 18篇 |
2023年 | 136篇 |
2022年 | 240篇 |
2021年 | 292篇 |
2020年 | 303篇 |
2019年 | 292篇 |
2018年 | 209篇 |
2017年 | 200篇 |
2016年 | 312篇 |
2015年 | 354篇 |
2014年 | 366篇 |
2013年 | 498篇 |
2012年 | 585篇 |
2011年 | 686篇 |
2010年 | 434篇 |
2009年 | 428篇 |
2008年 | 492篇 |
2007年 | 429篇 |
2006年 | 423篇 |
2005年 | 406篇 |
2004年 | 287篇 |
2003年 | 254篇 |
2002年 | 251篇 |
2001年 | 221篇 |
2000年 | 169篇 |
1999年 | 166篇 |
1998年 | 154篇 |
1997年 | 135篇 |
1996年 | 144篇 |
1995年 | 153篇 |
1994年 | 116篇 |
1993年 | 107篇 |
1992年 | 73篇 |
1991年 | 99篇 |
1990年 | 61篇 |
1989年 | 62篇 |
1988年 | 50篇 |
1987年 | 31篇 |
1986年 | 22篇 |
1985年 | 18篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1966年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有9721条查询结果,搜索用时 15 毫秒
91.
Yang K Chen LP Cai YQ Hiraoka N Li S Zhao JF Shen DW Song HF Tian H Bai LH Chen ZH Shuai ZG Feng DL 《Physical review letters》2007,98(3):036404
Excitons in a complex organic molecular crystal were studied by inelastic x-ray scattering (IXS) for the first time. The dynamic dielectric response function is measured over a large momentum transfer region, from which an exciton dispersion of 130 meV is observed. Semiempirical quantum chemical calculations reproduce well the momentum dependence of the measured dynamic dielectric responses, and thus unambiguously indicate that the lowest Frenkel exciton is confined within a fraction of the complex molecule. Our results demonstrate that IXS is a powerful tool for studying excitons in complex organic molecular systems. Besides the energy position, the IXS spectra provide a stringent test on the validity of the theoretically calculated exciton wave functions. 相似文献
92.
Cai Xiang-Ming Shan Jian Le Yun-Lin Luo Yuan Li Ya-Dong 《Journal of Radioanalytical and Nuclear Chemistry》2021,330(3):747-753
Journal of Radioanalytical and Nuclear Chemistry - The rapid measurement of radon progeny concentration is of great significance for improving the efficiency of radon exposure dose evaluation in a... 相似文献
93.
94.
95.
96.
Zhang-Yu Nie Rong-Gen Cai Xin Gao Li Li Hui Zeng 《The European Physical Journal C - Particles and Fields》2015,75(11):559
In a previous paper (Nie et al. in JHEP 1311:087, arXiv:1309.2204 [hep-th], 2013), we presented a holographic s \(+\) p superconductor model with a scalar triplet charged under an SU(2) gauge field in the bulk. We also study the competition and coexistence of the s-wave and p-wave orders in the probe limit. In this work we continue to study the model by considering the full back-reaction. The model shows a rich phase structure and various condensate behaviors such as the “n-type” and “u-type” ones, which are also known as reentrant phase transitions in condensed matter physics. The phase transitions to the p-wave phase or s \(+\) p coexisting phase become first order in strong back-reaction cases. In these first order phase transitions, the free energy curve always forms a swallow tail shape, in which the unstable s \(+\) p solution can also play an important role. The phase diagrams of this model are given in terms of the dimension of the scalar order and the temperature in the cases of eight different values of the back-reaction parameter, which show that the region for the s \(+\) p coexisting phase is enlarged with a small or medium back-reaction parameter but is reduced in the strong back-reaction cases. 相似文献
97.
The phase transitions, lattice dynamical and thermodynamic properties of BeS, BsSe and BeTe at high pressure have been investigated with the density functional theory. The calculated equilibrium structural parameters agree well with the available experimental and theoretical values. The phase transition pressures from the zinc-blende (ZB) to the nickel arsenide (NiAs) phase of these compounds are determined. The calculated phonon dispersion curves of these compounds in ZB phase at zero pressure do not show any anomaly or instability. Dynamically, the ZB phase of BeS, BeSe and BeTe is found to be stable near transition pressures PT. Within the quasiharmonic approximation, the thermodynamic properties including the thermal expansion coefficient, heat capacity at constant volume, heat capacity at constant pressure and entropy are predicted. 相似文献
98.
文章讨论了"对物理教材中两个概念的讨论"一文的"加减平衡力系"的不当之处,其根本原因在于弹簧是变形体,而"加减平衡力系"的公理只适应于刚体.使用了一个弹簧振子的例子进行佐证.目前的教学只强调解题速度,为了提高速度而占用了大量的学习资源,导致学生无暇理解科学的本质和科学的美.建议当代教学应强调通用解法和基本思路. 相似文献
99.
Polymers based on styrene (STY) and divinylbenzene (DVB) are widely used for water treatment. The chemical modification of these materials, with the introduction of chemical groups, increases their selectivity for certain types of contaminants. The incorporation of magnetic particles makes these systems useful for removing contaminants from aquifers, due to their magnetic attraction of certain residues. In this work, STY–DVB resins (unmodified, sulfonated, and impregnated with nickel and cobalt particles) were analyzed by thermogravimetry. The thermal stabilities of all the samples were compared, showing that sulfonation reduces the thermal stability of the resin, but the incorporation of metal particles restores that stability, with the extent of this recovery depending on the type of metal. This result shows that even when the incorporation of metal particles does not involve removal of contaminants by magnetic attraction, this inclusion is still justified because it increases the material’s thermal stability and also makes it more efficient for removing certain types of non-metallic contaminants, as observed in a previous study. Besides this, the thermogravimetric analysis was highly useful to ascertain the changes caused to the materials, including allowing inferences on the semi-quantitative results of the degree of sulfonation and confirming that metal compounds are not only physical mixtures. 相似文献
100.
Azobenzene‐Functionalized Metal–Organic Polyhedra for the Optically Responsive Capture and Release of Guest Molecules 下载免费PDF全文
Dr. Jinhee Park Dr. Lin‐Bing Sun Ying‐Pin Chen Zachary Perry Prof. Dr. Hong‐Cai Zhou 《Angewandte Chemie (International ed. in English)》2014,53(23):5842-5846
Stimuli‐responsive metal–organic polyhedra (srMOPs) functionalized with azobenzene showed UV‐irradiation‐induced isomerization from the insoluble trans‐srMOP to the soluble cis‐srMOP, whereas irradiation with blue light reversed this process. Guest molecules were trapped and released upon cis‐to‐trans and trans‐to‐cis isomerization of the srMOPs, respectively. This study provides a new direction in the ever‐diversifying field of MOPs, while laying the groundwork for a new class of optically responsive materials. 相似文献