全文获取类型
收费全文 | 11473篇 |
免费 | 73篇 |
国内免费 | 32篇 |
专业分类
化学 | 4664篇 |
晶体学 | 14篇 |
力学 | 713篇 |
数学 | 4030篇 |
物理学 | 2157篇 |
出版年
2024年 | 117篇 |
2023年 | 690篇 |
2022年 | 418篇 |
2021年 | 411篇 |
2020年 | 1456篇 |
2019年 | 1067篇 |
2018年 | 926篇 |
2017年 | 753篇 |
2016年 | 733篇 |
2015年 | 562篇 |
2014年 | 737篇 |
2013年 | 2832篇 |
2012年 | 494篇 |
2011年 | 25篇 |
2010年 | 22篇 |
2009年 | 10篇 |
2008年 | 26篇 |
2007年 | 22篇 |
2006年 | 16篇 |
2005年 | 69篇 |
2004年 | 79篇 |
2003年 | 29篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 1篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 10篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
93.
Mouna Smida Jérome Lhôste Mohamed Dammak Santiago Garcia-Granda 《Arabian Journal of Chemistry》2019,12(8):2519-2523
Crystal structure of Fe2F5(H2O)(Htaz)(taz)(Hdma) which crystallizes in the triclinic system space group with unit cell parameters a = 8.8392(5) Å, b = 9.1948(5) Å, c = 9.5877(5) Å, α = 82.070(3)°, β = 63.699(3)°, γ = 89.202(3)°, Z = 2, and V = 690.91(7) Å3, was synthesized under hydrothermal conditions at 393 K for 72 h, by a mixture of FeF2/FeF3, 1,2,4-triazole molecule (Htaz), and hydrofluoric acid solution (HF 4%) in dimethylformamide solvent (DMF). The main feature of this material is the coexistence of two oxidation states for iron atoms (Fe2+, Fe3+) in the unit cell, which associate by opposite fluorine corners of FeF5N and FeF2N4 octahedra, and/or triazole molecule which originates the 2D produces material. The structure determination, performed from single crystal X-ray diffraction data, lead to the R1/WR2 reliability factors 0.031/0.087. Thermal stability studies (TG/DTG/DTA) show that the decomposition provides in the temperature range 473–773 K and no mass loss was detected before 473 K. Mass spectrometry (MS) has been used. The optical absorption of the solid was measured at the corresponding λmax using UV–vis diffuse-reflectance spectrum. 相似文献
94.
95.
In this paper, we study the following Klein–Gordon–Maxwell system Using variational methods, we obtain the existence of ground state solutions under some appropriate assumptions on and . 相似文献
96.
97.
We analytically obtained the Schmidt decomposition of the entangled state between the pseudo spin and the true spin in graphene with Rashba spin–orbit coupling. The entangled state has the standard form of the Bell state, where the SU(2) spin symmetry is broken. These states can be explicitly expressed as the superposition of two nonorthogonal, but mirror symmetrical spin states entangled with the pseudo spin states. Because of the closely locking between the pseudo spin and the true spin, it is found that the orbit curve in the spin-polarization parameter space for the fixed equi-energy contour around Dirac points has the same shape as the -contour. Due to the spin–orbit coupling that cause the topological transition in the local geometry of the dispersion relation, the new equi-energy contours around the new emergent Dirac Points can be obtained by squeezing the one around the original Dirac point. The spin texture in the momentum space around the Dirac points is analyzed under the Rashba spin–orbit interaction and it is found that the orientation of the spin polarization at each crystal momentum is independent of the Rashba coupling strength. 相似文献
98.
The Kakutani–Bebutov Theorem (1968) states that any compact metric real flow whose fixed point set is homeomorphic to a subset of embeds into the Bebutov flow, the -shift on . An interesting fact is that this universal space is a function space. However, it is not compact, nor locally compact. We construct an explicit countable product of compact subspaces of the Bebutov flow which is a universal space for all compact metric real flows, with no restriction; namely, into which any compact metric real flow embeds. The result is compared to previously known universal spaces. 相似文献
99.
Razieh Fazaeli Hamid Aliyan Elham Naderi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):745-754
Abstract The immobilization of heteropoly acids (HPAs) into the Al-functionalized KIT-6 mesoporous molecular sieve has been carried out to see the effect of Al-KIT-6 as a host matrix on the HPA activities. These modified mesoporous molecular sieves are effective catalysts for the Hosomi–Sakurai three-component coupling reaction via condensation of aldehydes, silyl ethers, and allylsilanes. Supplemental materials are available for this paper. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
100.
Irina L. Odinets Oleg I. Artyushin Elena V. Sharova Ekaterina V. Matveeva Alexandr N. Turanov Vasilii K. Karandashev 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):146-149
Abstract The extraction properties of a series of carbamoylmethylphosphine oxides and β-aminophosphine oxides with lanthanide metal ions is presented. Tris[bis(2-diphenyl- phosphorylethyl)-aminoethyl]amine is shown to be highly effective for extraction of Re(VII). 相似文献