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21.
Symmetrical broken and nonlinear response of Weyl semimetal TaAs influenced by the topological surface states and Weyl nodes 下载免费PDF全文
A Weyl semimetal (WSM) features Weyl fermions in its bulk and topological surface states on surfaces, and is novel material hosting Weyl fermions, a kind of fundamental particles. The WSM was regarded as a three‐dimensional version of “graphene” under the illusion. In order to explore its promising photoelectric properties and applications in photonics and photoelectronics, here, we study the anisotropic linear and nonlinear optical responses of a WSM TaAs, which are determined by the relationship and balance between its topological surface states and Weyl nodes. We demonstrate that topological surface states which break the bulk symmetry are responsible for the anisotropy of the mobility, and the anisotropic nonlinear response shows saturable characteristic with extremely large saturable intensity. We also find that the mobility is anisotropic with the magnitude of 104 cm2V−1s−1 at room temperature and can be accelerated by the optical field. By analyzing the symmetry, the nonlinear response is mainly contributed by the fermions close to the Weyl nodes, and is related to the Pauli's blocking of fermions, electron‐electron interaction. This work experimentally discovers the anisotropic ultrahigh mobility of WSMs in the optical field and may start the field for the applications of WSMs in photonics and photoelectronics.
22.
Lichang Yin Yunzuo Liu Jingbin Lu Guangyi Zhao Xianfeng Li Xiaoguang Wu Guangsheng Li Shuxian Wen Chunxiang Yang 《The European Physical Journal A - Hadrons and Nuclei》2001,11(4):379-383
High-spin states of 160Lu have been studied through the 144Sm( 19F, 3n) reaction. The previously known πh
11/2⊗υi
13/2 yrast band is extended from I
π = 21- to 25- and a four quasiparticle band with configuration πh
11/2[523]7/2 -⊗υh
9/2[521]3/2 -⊗ (υi
13/2)2 is reported.
Received: 21 May 2001 / Accepted: 19 July 2001 相似文献
23.
用HREELS, AES, LEED和TDS考察了氮在含氧Mo(100)上的吸附和热脱附. 120 K下氮在含氧Mo(100)上吸附时存在着N—N伸缩振动频率2150和1600 cm-1, 分别对应于线式(γ态)和侧位(α态)两种分子吸附态. 升温引起γ态氮的脱附和α态氮的解离. 其中γ态氮的脱附峰温位于155 K, 遵循一级脱附动力学; 由α态解离生成的N原子占据Mo(100)的四重空位(即β态), 并在高于1?150 K的温度重新化合形成氮而脱附. 120 K时,氮的吸附是无序的; 吸附了氮的表面经1100 K退火后生成了有序的c(2×2)-N表面结构. 相似文献
24.
Cu-Cr and Cu-Cr-Zr catalysts for the low temperature methanol synthesis slurry phase, with the surface area of 77.9 and 113.2 m2/g respectively, were prepared by the co precipitation approach. The activity and selectivity of these catalysts were evaluated in a stainless steel autoclave at 5.5 MPa and at different temperatures of 383 and 423 K separately. It was found that the activity of Cu-Cr-Zr catalyst was obviously higher than that of Cu-Cr catalyst, whereas the methanol selectivity of Cu-Cr-Zr catalyst was a little lower. The concentration of sodium compounds in the solution after reaction was also measured. The results showed that the concentration of sodium formate after reaction is much lower than that before reaction, which is quite different from the observations from the Cu-Cr catalyst previously. This implies that the conversion of sodium methoxide to sodium formate has been completely suppressed in the presence of zirconia in Cu-Cr-Zr catalyst. This finding is more beneficial to improve the performance of Cu-Cr catalyst and to increase the life of catalyst system as well. 相似文献
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由于国家对石油产品中含硫量的严格控制,原油脱硫已成为石油化工生产中的一项紧迫任务.硫化钼作为高效加氢脱硫催化剂而被广泛研究.过渡金属Co掺杂提高了传统钼基硫化物加氢脱硫催化剂的催化活性,目前被广泛应用于原油催化脱硫.本文采用密度泛函理论,对Co修饰MoS2三角形团簇边缘不饱和活性位(CUS)的形成及甲硫醇的催化脱硫过程进行了理论研究.结果表明,活性位形成过程中,氢气裂解的活性位为Mo原子和S原子,随后形成硫化氢并脱附.甲硫醇倾向于吸附在CUS的TopCo位.通过电荷布居及前线轨道分析发现,Co的引入改变了表面原子电荷及CUS的LUMO轨道分布,并且Co表现出强吸电子能力,从而促进甲硫醇的吸附.CH3SH最优脱硫路径为先后断裂S-H和C-S键形成甲烷实现脱硫,其中形成甲烷的基元步骤为整个脱硫反应的速率控制步骤,其能垒为1.51 eV. 相似文献
27.
高血压患者血清中铁锌铜锰硒铬含量的研究 总被引:2,自引:1,他引:2
165例高血压患者血清中铁,锌,铜,锰,硒,铬的含量与对照组比较,结果显示:1.微量元素铁,锌含量明显升高,而血清铜,铬含量明显降低,其差异均有高度显著性,P〈0.01;血清锰和硒的含量,两者差异无显著性,P〉0.01.2.上述元素含量的特点可用高血压病的早期预报和治疗。 相似文献
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30.
NIR-II Fluorescent Brightness Promoted by “Ring Fusion” for the Detection of Intestinal Inflammation
Yaxi Li Menglei Zha Dr. Guang Yang Shuxian Wang Prof. Jen-Shyang Ni Prof. Kai Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(51):13085-13091
Fluorophores with emission in the second near-infrared window (NIR-II) have displayed salient advantages for biomedical applications. However, the common strategy of reducing the energy bandgap of fluorophores so as to achieve red-shifted wavelengths always leads to compromised fluorescent brightness. Herein, we propose a molecular design concept of “ring-fusion” to modify the acceptor of AIEgen that can extend the luminous wavelength from NIR-I to NIR-II. The fused-acceptor-containing fluorophore yielded, TTQP, has an enhanced absorption coefficient with a higher brightness in nanoparticle formation compared to its NIR-I emissive counterpart (TTQ-DP) with a non-fused acceptor. Theoretical calculation further confirms that the ring fusion can efficiently promote the rigidity and planarity of the electron-deficient core, leading to a lower reorganization energy and nonradiative decay. The TTQP NPs yielded thus allow sensitive NIR-II fluorescence imaging of vasculature and intestinal inflammation in mice models. Therefore, we anticipate that our work will provide a promising molecular-engineering strategy to enrich the library and broaden the application scope of NIR-II fluorophores. 相似文献