全文获取类型
收费全文 | 325篇 |
免费 | 47篇 |
国内免费 | 47篇 |
专业分类
化学 | 186篇 |
晶体学 | 2篇 |
力学 | 23篇 |
综合类 | 4篇 |
数学 | 18篇 |
物理学 | 38篇 |
无线电 | 148篇 |
出版年
2024年 | 6篇 |
2023年 | 17篇 |
2022年 | 17篇 |
2021年 | 30篇 |
2020年 | 30篇 |
2019年 | 20篇 |
2018年 | 19篇 |
2017年 | 22篇 |
2016年 | 27篇 |
2015年 | 20篇 |
2014年 | 30篇 |
2013年 | 28篇 |
2012年 | 23篇 |
2011年 | 21篇 |
2010年 | 19篇 |
2009年 | 14篇 |
2008年 | 13篇 |
2007年 | 13篇 |
2006年 | 5篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有419条查询结果,搜索用时 15 毫秒
171.
Zirconia nanotube-supported H3PW12O40 (HPW) catalysts exhibit high catalytic activities in the synthesis of fatty acid ethyl ester. 相似文献
172.
Wang Xuegang Liu Yajie Sun Zhanxue Li Jiang Chai Liyuan Min Xiaobo Guo Yadan Li Peng Zhou Zhongkui 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(1):251-258
Journal of Radioanalytical and Nuclear Chemistry - We evaluated uranium bioleaching from low-grade, granite-type uranium ore using mixed acidophilic microbes from uranium mine leachate. A 4854-ton... 相似文献
173.
174.
175.
陈理元 《浙江大学学报(理学版)》1994,21(3):245-254
本文利用变测度内插定理,权乘子理论等方法,得到了Riesz-mean算子的加权估计.把Sogge的一些结论推广到带权情形,并将Sogge的结论中的LD有界性的P范围扩充到1
相似文献
176.
Haoran Long Hao Liu Xiaoyu Wang Bowen Wang Ruixue Bai Yali Yu Kaiyao Xin Liyuan Liu Yingqiang Xu Jing Zhang Fagang Jiang Xinghua Wang Zhongming Wei Juehan Yang 《Advanced functional materials》2023,33(49):2306241
Facing the future development trend of miniaturization and intelligence of electronic devices, solar-blind photodetectors based on ultrawide-bandgap 2D semiconductors have the advantages of low dark current, and high signal-to-noise ratio, as well as the features of micro-nanometer miniaturization and multi-functionalization of 2D material devices, which have potential applications in the photoelectric sensor part of high-performance machine vision systems. This study reports a 2D oxide semiconductor, AsSbO3, with an ultrawide bandgap (4.997 eV for monolayer and 4.4 eV for multilayer) to be used to fabricate highly selective solar-blind UV photodetectors, of which the dark current as low as 100 fA and rejection ratio of UV-C and UV-A reaches 7.6 × 103. Under 239 nm incident light, the responsivity is 105 mA W−1 and the detectivity is 7.58 × 1012 Jones. Owing to the remarkable anisotropic crystal structure, AsSbO3 also shows significant linear dichroism and nonlinear optical properties. Finally, a simple machine vision system is simulated by combining the real-time imaging function in solar-blind UV with a convolutional neural network. This study enriches the material system of ultrawide-bandgap 2D semiconductors and provides insight into the future development of high-performance solar-blind UV optoelectronic devices. 相似文献
177.
The application of SUPREX (stability of unpurified proteins from rates of H/D exchange) to the thermodynamic analysis of protein-DNA complexes is described. A series of five model protein-DNA complexes involving two known DNA binding proteins, Arc repressor and CopG, were analyzed in order to determine the accuracy, precision, and generality of the SUPREX technique for quantifying the strength of protein-DNA interactions. For protein-DNA complexes that reversibly unfold in a two-state manner, we demonstrate that reasonably precise Kd values in agreement with those determined by conventional techniques can be determined by SUPREX. In the case of protein-DNA complexes that are not well modeled by a two-state unfolding mechanism, we find that relative binding affinities can be determined in the SUPREX experiment. 相似文献
178.
Tianli Feng Xuewang Wu Xiaolong Yang Peipei Wang Liyuan Zhang Xu Du Xiaojia Wang Sokrates T. Pantelides 《Advanced functional materials》2020,30(5)
Hafnium pentatelluride (HfTe5) has attracted extensive interest due to its exotic electronic, optical, and thermal properties. As a highly anisotropic crystal (layered structure with in‐plane chains), it has highly anisotropic electrical‐transport properties, but the anisotropy of its thermal‐transport properties has not been established. Here, accurate experimental measurements and theoretical calculations are combined to resolve this issue. Time‐domain thermoreflectance measurements find a highly anisotropic thermal conductivity, 28:1:8, with values of 11.3 ± 2.2, 0.41 ± 0.04, and 3.2 ± 2.0 W m-1 K-1 along the in‐plane a‐axis, through‐plane b‐axis, and in‐plane c‐axis, respectively. This anisotropy is even larger than what was recently established for ZrTe5 (12:1:6), but the individual values are somewhat higher, even though Zr has a smaller atomic mass than Hf. Density‐functional‐theory calculations predict thermal conductivities in good agreement with the experimental data, provide comprehensive insights into the results, and reveal the origin of the apparent anomaly of the relative thermal conductivities of the two pentatellurides. These results establish that HfTe5 and ZrTe5, and by implication their alloys, have highly anisotropic and ultralow through‐plane thermal conductivities, which can provide guidance for the design of materials for new directional‐heat‐management applications and potentially other thermal functionalities. 相似文献
179.
钯系催化剂的制备及其在催化氢化中的应用 总被引:7,自引:2,他引:7
钯系催化剂的制备及其在催化氢化中的应用陈一飞,丘礼元,李和兴(上海师范大学化学系上海200234)关键词钯络合催化剂,镍一钯复合催化剂,催化氢化脂肪烯烃和芳烃硝基衍生物种类繁多,其氢化产物广泛应用在食品工业、染料工业、高分子工业以及日用化工等领域。合... 相似文献
180.
Zhongde Dai Lu Bai Karoline Nåvik Hval Xiangping Zhang Suojiang Zhang Liyuan Deng 《中国科学:化学(英文版)》2016,59(5):538-546
In this study a thin film composite (TFC) membrane with a Pebax/Task-specific ionic liquid (TSIL) blend selective layer was prepared. Defect-free Pebax/TSIL layers were coated successfully on a polysulfone ultrafiltration porous support with a polydimethylsiloxane (PDMS) gutter layer. Different parameters in the membrane preparation (e.g. concentration, coating time) were investigated and optimized. The morphology of the membranes was studied by scanning electron microscopy (SEM), while the thermal properties and chemical structures of the membrane materials were investigated by thermo-gravimetric analyzer (TGA), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The CO2 separation performance of the membrane was evaluated using a mixed gas permeation test. Experimental results show that the incorporation of TSIL into the Pebax matrix can significantly increase both CO2 permeance and CO2/N2 selectivity. With the presence of water vapor, the membrane exhibits the best CO2/N2 selectivity at a relative humidity of around 75%, where a CO2 permeance of around 500 GPU and a CO2/N2 selectivity of 46 were documented. A further increase in the relative humidity resulted in higher CO2 permeance but decreased CO2/N2 selectivity. Experiments also show that CO2 permeance decreases with a CO2 partial pressure increase, which is considered a characteristic in facilitated transport membranes. 相似文献