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排序方式: 共有193条查询结果,搜索用时 18 毫秒
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In this paper, we propose a new estimation method for a nonparametric hidden Markov model(HMM), in which both the emission model and the transition matrix are nonparametric, and a semiparametric HMM, in which the transition matrix is parametric while emission models are nonparametric. The estimation is based on a novel composite likelihood method, where the pairs of consecutive observations are treated as independent bivariate random variables. Therefore, the model is transformed into a mixture ... 相似文献
113.
高妍琦 季来林 崔勇 饶大幸 赵晓晖 冯伟 夏兰 刘栋 王韬 史海涛 李福建 刘佳 杜鹏远 李小莉 刘佳妮 张天雄 单翀 马伟新 隋展 傅思祖 《强激光与粒子束》2020,32(1):011004-1-011004-2
激光等离子体相互作用的不稳定性将有望通过降低高功率激光装置输出光束的相干性得到大幅缓解。利用低相干光源作为种子源,采用钕玻璃放大介质,研制成功国际首台kJ级大带宽低相干激光装置,实现了带宽13 nm、能量960 J、脉宽3~10 ns可调,相干时间仅为300 fs的大能量光脉冲输出。输出脉冲光谱匀滑无纵模结构,且谱相位随机分布,可实现脉冲波形和光谱分布的无关联精密调控。该装置不仅成功演示验证了低相干激光驱动器的单元技术及系统集成技术,同时也为激光等离子体相互作用及高能量密度物理研究提供了全新的实验研究平台。 相似文献
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Xuanyu Zhang Dr. Rui You Zeyue Wei Dr. Xiao Jiang Dr. Jiuzhong Yang Prof. Yang Pan Dr. Peiwen Wu Qingdong Jia Dr. Zhenghong Bao Dr. Lei Bai Prof. Mingzhou Jin Dr. Bobby Sumpter Dr. Victor Fung Prof. Weixin Huang Dr. Zili Wu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(21):8045-8045
116.
Muqing Ren Dr. Kun Qian Prof. Dr. Weixin Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(70):15978-15982
Electronic metal-support interactions (EMSIs) of oxide-supported metal catalysts strongly modifies the electronic structures of the supported metal nanoparticles. The strong influence of EMSIs on the electronic structures of oxide overlayers on metal nanoparticles employing cerium oxides/Ag inverse catalysts is reported herein. Ce2O3 overlayers were observed to exclusively form on Ag nanocrystals at low cerium loadings and be resistant to oxidation treatments up to 250 °C, whereas CeO2 overlayers gradually developed as the cerium loading increased. Ag cubes enclosed by {001} facets with a smaller work function exert a stronger EMSI effect on the CeOx overlayers than Ag cubes enclosed by {111} facets. Only the CeO2 overlayers with a fully developed bulk CeO2 electronic structure significantly promote the catalytic activity of Ag nanocrystals in CO oxidation, whereas cerium oxide overlayers with other electronic structures do not. These results successfully extend the concept of EMSIs from oxide-supported metal catalysts to metal-supported oxide catalysts. 相似文献
117.
Dr. Kun Qian Huimei Duan Dr. Yangyang Li Prof. Dr. Weixin Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(60):13538-13542
Strong metal–support interaction of supported metal catalysts is an important concept to describe the effect of metal–support interactions on the structures and catalytic performances of supported metal particles. By using an example of CeOx adlayers supported on Ag nanocrystals, herein a concept of electronic oxide–metal strong interaction (EOMSI) is put forward; this interaction significantly affects the electronic structures of oxide adlayers through metal-to-oxide charge transfer. The EOMSI can stabilize oxide adlayers in a low oxidation state under ambient conditions, which individually are not stable; moreover, the oxide adlayers experiencing the EOMSI are resistant to high-temperature oxidation in air to a certain extent. Such an EOMSI concept helps to generalize the strong influence of oxide–metal interactions on the structures and catalytic performance of oxide/metal inverse catalysts, which have been attracting increasing attention. 相似文献
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Ma Yu Dou Weixin Yang Weiting Yang Weikang Pan Qinhe 《Journal of Radioanalytical and Nuclear Chemistry》2021,329(2):1011-1017
Journal of Radioanalytical and Nuclear Chemistry - Recently, highly porous metal–organic frameworks (MOFs), with excellent porosity and abundant functional groups, have represented a new... 相似文献
120.
Xian J Hua Q Jiang Z Ma Y Huang W 《Langmuir : the ACS journal of surfaces and colloids》2012,28(17):6736-6741
Pd nanocrystals were prepared by the reduction of a H(2)PdCl(4) aqueous solution with C(2)H(4) in the presence of different amounts of poly(N-vinyl-2-pyrrolidone) (PVP). Their average size decreases monotonically as the PVP monomer/Pd molar ratio increases up to 1.0 and then does not vary much at higher PVP monomer/Pd molar ratios. Infrared spectroscopy and X-ray photoelectron spectroscopy results reveal the interesting size-dependent interaction of PVP molecules with Pd nanocrystals. For fine Pd nanocrystals capped with a large number of PVP molecules, each PVP molecule chemisorbs with its oxygen atom in the ring; for large Pd nanocrystals capped by a small number of PVP molecules, each PVP molecule chemisorbs with both the oxygen atom and nitrogen atom in the ring, which obviously affects the structure of chemisorbed PVP molecules and even results in the breaking of involved C-N bonds of some chemisorbed PVP molecules. Charge transfer always occurs from a chemisorbed PVP ligand to Pd nanocrystals. These results provide novel insights into the PVP-metal nanocrystal interaction, which are of great importance in the fundamental understanding of surface-mediated properties of PVP-capped metal nanocrystals. 相似文献