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排序方式: 共有113条查询结果,搜索用时 11 毫秒
91.
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Chen Liang Wenhua Zhang Zesen Wei Zhaoyu Wang Qingsong Wang Jinhua Sun 《Journal of Energy Chemistry》2021,(8):446-454
Based on the synchrotron soft X-ray absorption spectroscopy experiments,the fundamental electronic structures of layered LiNixCoyMnzO2 (NCM) are investigated sy... 相似文献
93.
Dr. Guillaume Povie Dr. Anh‐Tuan Tran Prof. David Bonnaffé Jacqueline Habegger Zhaoyu Hu Dr. Christine Le Narvor Prof. Philippe Renaud 《Angewandte Chemie (International ed. in English)》2014,53(15):3894-3898
Thiol‐ene coupling (TEC) reactions emerged as one of the most useful processes for coupling different molecular units under reaction mild conditions. However, TEC reactions involving weak C? H bonds (allylic and benzylic fragments) are difficult to run and often low yielding. Mechanistic studies demonstrate that hydrogen‐atom transfer processes at allylic and benzylic positions are responsible for the lack of efficiency of the radical‐chain process. These competing reactions cannot be prevented, but reported herein is a method to repair the chain process by running the reaction in the presence of triethylborane and catechol. Under these reaction conditions, a unique repair mechanism leads to an efficient chain reaction, which is demonstrated with a broad range of anomeric O‐allyl sugar derivatives including mono‐, di‐, and tetrasaccharides bearing various functionalities and protecting groups. 相似文献
94.
外周天线LHC在光合作用过程中,担负着吸收和传递光能的作用.我们采用扫描成象荧光光谱技术对菠菜中外周天线LHC的荧光光谱特性进行了研究,在514.5nm的激光激励下获取了积分荧光谱,认为从类胡萝卜素分子到叶绿素分子间存在有能量传递.采用高斯组分光谱解析的方法,解析出LHC的荧光发射有七个谱带:656.7、664.6、671.5、677.2、683.5、689.6、695.3nm,各自所占的比例分别为3.0%、13.1%、13.3%、21.1%、13.2%、33.3%、3.0%,其中658.7nm的发射谱是由叶绿素b分子所发射的,其余的发射谱分别是由吸收峰为662、670/671、676、680nm以及吸收大于690nm的叶绿素a分子所发射.3.0%的叶绿素b分子的荧光发射说明在能量平衡过程中绝大部分能量被叶绿素a分子所禁锢,689.6nm处的荧光所占的比例最大,可能与LHC的一种自保护机制有关 相似文献
95.
Density functional theory investigations show that the Li+ ion is stabilized at the center of hexagonal carbon ring with the distance of 1.84 Å from graphene surface. The potential barrier of Li+ ion diffusion on the graphene surface, about 0.32 eV, is much lower than that of Li+ ion penetrating the carbon ring which is 10.68 eV. When a vacancy of graphene exists, potential barrier about 10.25 eV for Li+ ion penetrating the defect is still high, and the ability of the vacancy to sizing the Li+ ion is also observed. Electronic densities of states show that the formation of a localized bond between Li atom and edge carbon of vacancy is the main reason for high potential barrier when Li+ ion penetrate a vacancy. While Coulomb repulsion is the control factor for high potential barrier in case of Li+ ion penetrating a carbon ring. 相似文献
96.
核心天线CP43、CP47的荧光光谱特性 总被引:1,自引:0,他引:1
采用快速扫描成象光谱技术对核心天线CP43和CP47的荧光光谱特性进行研究,获取了它们的积分荧光谱,通过积分荧光谱的组分光谱解析,并结合吸收光谱分析认为CP43和CP47具有这样的Chla的光谱特性,CP43:Chla660662.43、Chla669670.23、Chla682684.02,CP47:Chla660664.91、Chla669671.71、Chla680681.35、(Chlaae,a代表吸收峰;e代表发射峰);另外长波长组分694.86nm、702.34nm(CP43)、696.02nm(CP47)可能是由吸收>690nm的Chla分子所产生;CP43与CP47相比还存在有Chla675676.32,但是还没有看到CP43具有675nm吸收谱带的报道.对CP43和CP47的荧光光谱分析,认为CP47中的Chla669nm分子团和Chla680nm分子团间的能量传递比CP43中Chla669nm和Chla682nm分子团的能量传递更为有效;β-Car与Chla分子结合状态在CP47中要比CP43中紧密. 相似文献
97.
Chongfeng Guo Jie YuJung-Hyun Jeong Zhaoyu RenJintao Bai 《Physica B: Condensed Matter》2011,406(4):916-920
A series of Eu3+ doped BaLa2ZnO5 was prepared by a Pechini-type sol-gel method. The effect of Eu3+ concentration on the structure and the luminescent properties of the samples BaLa2−xEuxZnO5 were investigated by powder X-ray diffraction (XRD) and photoluminescence (PL) spectra. The sample adopts the tetragonal or orthorhombic structure as the Eu3+ concentration reaches below 1.2 or over 1.6, respectively. The sample is a mixture of tetragonal and orthorhombic phases as the contents of dopants lie between 1.2 and 1.6. The phosphor offers the strongest red light as content of Eu3+ is 0.4. In addition, the crystallization processes of the complex precursors were examined by simultaneous thermogravimetry and differential thermal analysis (TG-DTA), and also the optimal heating temperature was investigated. 相似文献
98.
Eu2+ activated Ca5(PO4)3Cl blue-emitting phosphors were prepared by the conventional solid state method using CaCl2 as the chlorine source and H3BO3 as flux. The structure and luminescent properties of phosphors depend on the concentrations of Eu2+, the amount of CaCl2 and the usage of the H3BO3 flux were investigated systematically. Eu2+ and Mn2+ Co-doped Ca5(PO4)3Cl with blue and orange double-band emissions were also researched based on the optimal composition and synthesis conditions. The energy transfer between Eu2+ and Mn2+ was found in the phosphor Ca5(PO4)3Cl:Eu2+, Mn2+, and the Co-doped phosphor can be efficiently excited by near-UV light, indicating that the phoshor is a potentional candidate for n-UV LED used phosphor. 相似文献
99.
100.