全文获取类型
收费全文 | 768篇 |
免费 | 164篇 |
国内免费 | 148篇 |
专业分类
化学 | 305篇 |
晶体学 | 23篇 |
力学 | 279篇 |
综合类 | 7篇 |
数学 | 19篇 |
物理学 | 447篇 |
出版年
2024年 | 7篇 |
2023年 | 19篇 |
2022年 | 36篇 |
2021年 | 54篇 |
2020年 | 35篇 |
2019年 | 36篇 |
2018年 | 39篇 |
2017年 | 28篇 |
2016年 | 45篇 |
2015年 | 36篇 |
2014年 | 46篇 |
2013年 | 115篇 |
2012年 | 50篇 |
2011年 | 51篇 |
2010年 | 49篇 |
2009年 | 43篇 |
2008年 | 44篇 |
2007年 | 43篇 |
2006年 | 36篇 |
2005年 | 33篇 |
2004年 | 35篇 |
2003年 | 29篇 |
2002年 | 20篇 |
2001年 | 14篇 |
2000年 | 19篇 |
1999年 | 7篇 |
1998年 | 13篇 |
1997年 | 15篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 5篇 |
1978年 | 1篇 |
排序方式: 共有1080条查询结果,搜索用时 0 毫秒
31.
32.
Yoichi Makimizu Nhat Truong Nguyen Jiri Tucek Hyo-Jin Ahn JeongEun Yoo Mahshid Poornajar Imgon Hwang Stepan Kment Prof. Dr. Patrik Schmuki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2685-2692
Photoelectrochemical (PEC) water splitting is a promising method for the conversion of solar energy into chemical energy stored in the form of hydrogen. Nanostructured hematite (α-Fe2O3) is one of the most attractive materials for a highly efficient charge carrier generation and collection due to its large specific surface area and the short minority carrier diffusion length. In the present work, the PEC water splitting performance of nanostructured α-Fe2O3 is investigated which was prepared by anodization followed by annealing in a low oxygen ambient (0.03 % O2 in Ar). It was found that low oxygen annealing can activate a significant PEC response of α-Fe2O3 even at a low temperature of 400 °C and provide an excellent PEC performance compared with classic air annealing. The photocurrent of the α-Fe2O3 annealed in the low oxygen at 1.5 V vs. RHE results as 0.5 mA cm−2, being 20 times higher than that of annealing in air. The obtained results show that the α-Fe2O3 annealed in low oxygen contains beneficial defects and promotes the transport of holes; it can be attributed to the improvement of conductivity due to the introduction of suitable oxygen vacancies in the α-Fe2O3. Additionally, we demonstrate the photocurrent of α-Fe2O3 annealed in low oxygen ambient can be further enhanced by Zn-Co LDH, which is a co-catalyst of oxygen evolution reaction. This indicates low oxygen annealing generates a promising method to obtain an excellent PEC water splitting performance from α-Fe2O3 photoanodes. 相似文献
33.
G Ananthakrishna 《Pramana》1979,12(5):543-561
The model introduced for clustering of quenched-in vacancies in the first part of this series of papers is considered. Using
a generating function, the rate equations are converted into a first order partial differential equation for the generating
function coupled to a differential equation for the rate of change of the concentration of single vacancy units. A decoupling
scheme is effected which gives an exponentially decaying solution with a very short time constant for the concentration of
single vacancy units. The differential equation for the generating function is solved for times larger than the time required
for the concentration of single vacancy units to reach its asymptotic value. The distribution for the size of the clusters
is obtained by inverting the solution thus obtained. Several results that follow are shown to be in reasonably good agreement
with the experimental results. 相似文献
34.
利用强流脉冲电子束(HCPEB)技术对多晶纯铝样品进行辐照,采用透射电子显微镜详细分析了辐照诱发的空位簇缺陷.HCPEP辐照后,在辐照表层内形成了大量的四方形空位胞,其间包含位错圈和堆垛层错四面体(SFT)等类型的空位簇缺陷.1次辐照后,空位胞内产生空位型位错圈,5次辐照则主要产生SFT;10次辐照后,空位胞内产生的空位簇缺陷主要是位错圈,局部区域也观察到了SFT缺陷,在产生SFT的附近区域具有很低的位错密度或者几乎无位错出现.HCPEB辐照产生的瞬间加热和冷却诱发了幅值极大且应变速率极高的应力,这一因素
关键词:
强流脉冲电子束
多晶纯铝
空位簇缺陷
堆垛层错四面体 相似文献
35.
Effect of surface oxygen vacancy defects on the performance of ZnO quantum dots ultraviolet photodetector 下载免费PDF全文
The slower response speed is the main problem in the application of ZnO quantum dots (QDs) photodetector, which has been commonly attributed to the presence of excess oxygen vacancy defects and oxygen adsorption/desorption processes. However, the detailed mechanism is still not very clear. Herein, the properties of ZnO QDs and their photodetectors with different amounts of oxygen vacancy (VO) defects controlled by hydrogen peroxide (H2O2) solution treatment have been investigated. After H2O2 solution treatment, VO concentration of ZnO QDs decreased. The H2O2 solution-treated device has a higher photocurrent and a lower dark current. Meanwhile, with the increase in VO concentration of ZnO QDs, the response speed of the device has been improved due to the increase of oxygen adsorption/desorption rate. More interestingly, the response speed of the device became less sensitive to temperature and oxygen concentration with the increase of VO defects. The findings in this work clarify that the surface VO defects of ZnO QDs could enhance the photoresponse speed, which is helpful for sensor designing. 相似文献
36.
Density functional theory study of formaldehyde adsorption and decomposition on Co-doped defective CeO_2(110) surface 下载免费PDF全文
《中国物理 B》2021,30(10):103101-103101
Formaldehyde as an air pollutant to adverse health effects for humanity has been getting attention. The adsorption and dissociation of formaldehyde(HCHO) on the Co_xCe_(1-x_O_(2-δ)(110) surface were investigated by the density functional theory(DFT) calculations. We calculated the oxygen vacancy formation energy as the function of its site around dopant Co in detail. The results showed that Co doping was accompanied by compensating oxygen hole spontaneous formation.The adsorption configurations and bindings of HCHO at different locations on the Co_xCe_(1-x)O_2(110) were presented.Four possible pathways of oxidation of formaldehyde on the catalytic surface were explored. The results suggested that formaldehyde dissociation at different adsorption sites on the doped CeO_2(110) — first forming dioxymethylene(CH_2O_2)intermediate, and then decomposing into H_2O, H_2, CO_2, and CO molecules. It was found that the presence of cobalt and oxygen vacancy significantly prompted the surface activity of CeO_2. 相似文献
37.
Abstract The kinetics of radiation defect accumulation and subsequent recovery during/after electron irradiation below 273 K, at 323 K and 373 K were investigated for the Fe-15.7 at.% Cr using positron annihilation measurements at room temperature. Formation of vacancy clusters was observed at all of the irradiation temperatures. The formation of clusters and kinetics of their accumulation point to mobility of vacancies at least at room temperature. The cluster rearrangement and variations in the cluster configuration take place during annealing. 相似文献
38.
Effect of lattice strain on the oxygen vacancy formation and hydrogen adsorption at CeO2(111) surface 总被引:1,自引:0,他引:1
Using first-principles calculation, the effect of lattice strain on the oxygen vacancy formation at CeO2(111) surface has been investigated. The tensile strain facilitates the oxygen vacancy formation at the surface and the compressive strain hinders the process. This is in part due to the strengthening or weakening of the surface Ce–O bond under the lattice strain. On the other hand, a more open surface with a larger lattice constant can better accommodate the larger Ce3+ and thus facilitate the structural relaxation of the reduced surface. The studies on the strain effect on the atomic hydrogen adsorption at the defect-free CeO2(111) surface show that the adsorption strength monotonously increases with the increase of the lattice strain, further confirming the tunable surface chemical activity by lattice strain. 相似文献
39.
40.
The influence of interfacial barrier engineering on the resistance switching of In<sub>2</sub>O<sub>3</sub>:SnO<sub>2</sub>/TiO<sub>2</sub>/In<sub>2</sub>O<sub>3</sub>:SnO<sub>2</sub> device 下载免费PDF全文
The I–V characteristics of In2O3:SnO2/TiO2/In2O3:SnO2 junctions with different interfacial barriers are inves- tigated by comparing experiments. A two-step resistance switching process is found for samples with two interfacial barriers produced by specific thermal treatment on the interfaces. The nonsynchronous occurrence of conducting filament formation through the oxide bulk and the reduction in the interfacial barrier due to the migration of oxygen vacancies under the electric field is supposed to explain the two-step resistive switching process. The unique switching properties of the device, based on interfacial barrier engineering, could be exploited for novel applications in nonvolatile memory devices. 相似文献