全文获取类型
收费全文 | 2894篇 |
免费 | 370篇 |
国内免费 | 280篇 |
专业分类
化学 | 2643篇 |
晶体学 | 101篇 |
力学 | 21篇 |
综合类 | 18篇 |
数学 | 5篇 |
物理学 | 756篇 |
出版年
2024年 | 6篇 |
2023年 | 30篇 |
2022年 | 59篇 |
2021年 | 72篇 |
2020年 | 110篇 |
2019年 | 91篇 |
2018年 | 66篇 |
2017年 | 68篇 |
2016年 | 119篇 |
2015年 | 124篇 |
2014年 | 135篇 |
2013年 | 264篇 |
2012年 | 169篇 |
2011年 | 154篇 |
2010年 | 145篇 |
2009年 | 170篇 |
2008年 | 178篇 |
2007年 | 164篇 |
2006年 | 207篇 |
2005年 | 147篇 |
2004年 | 164篇 |
2003年 | 150篇 |
2002年 | 132篇 |
2001年 | 76篇 |
2000年 | 85篇 |
1999年 | 76篇 |
1998年 | 61篇 |
1997年 | 61篇 |
1996年 | 51篇 |
1995年 | 48篇 |
1994年 | 28篇 |
1993年 | 29篇 |
1992年 | 31篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有3544条查询结果,搜索用时 46 毫秒
201.
Hailong Xiong Hongru Zhou Ge Sun Zhilin Liu Liangliang Zhang Ling Zhang Fei Du Zhen‐An Qiao Sheng Dai 《Angewandte Chemie (International ed. in English)》2020,59(27):11053-11060
Mesoporous metal oxides (MMOs) have been demonstrated great potential in various applications. Up to now, the direct synthesis of MMOs is still limited to the solvent induced inorganic‐organic self‐assembly process. Here, we develop a facile, general, and high throughput solvent‐free self‐assembly strategy to synthesize a series of MMOs including single‐component MMOs and multi‐component MMOs (e.g., doped MMOs, composite MMOs, and polymetallic oxide) with high crystallinity and remarkable porous properties by grinding and heating raw materials. Compared with the traditional solution self‐assembly process, the avoidance of solvents in this method not only greatly increases the yield of target products and synthesis efficiency, but also reduces the environmental pollution and the consumption of cost and energy. We believe the presented approach will pave a new avenue for scalable production of advanced mesoporous materials for various applications. 相似文献
202.
Fang Yuanxing Zheng Yun Fang Tao Chen Yong Zhu Yaodong Liang Qing Sheng Hua Li Zhaosheng Chen Chuncheng Wang Xinchen 《中国科学:化学(英文版)》2020,63(2):149-181
Photocatalysis,which is the catalyzation of redox reactions via the use of energy obtained from light sources,is a topic that has garnered a lot of attention in recent years as a means of addressing the environmental and economic issues plaguing society today.Of particular interest are photosynthesis can potentially mimic a variety of vital reactions,many of which hold the key to develop sustainable energy economy.In light of this,many of the technological and procedural advancements that have recently occurred in the field are discussed in this review,namely those linked to:(1)photocatalysts made from metal oxides,nitride,and sulfides;(2)photocatalysis via polymeric carbon nitride(PCN);and(3)general advances and mechanistic insights related to TiO2-based catalysts.The challenges and opportunities that have arisen over the past few years are discussed in detail.Basic concepts and experimental procedures which could be useful for eventually overcoming the problems associated with photocatalysis are presented herein. 相似文献
203.
Ling Xie Yan Yan Huijuan Lin Kun Rui Aoming Huang Min Du Yu Shen Jixin Zhu 《化学:亚洲杂志》2020,15(7):1105-1109
Owing to the high specific capacity and energy density, metal oxides have become very promising electrodes for lithium‐ion batteries (LIBs). However, poor electrical conductivity accompanied with inferior cycling stability resulting from large volume changes are the main obstacles to achieve a high reversible capacity and stable cyclability. Herein, a facile and general approach to fabricate SnO2, Fe2O3 and Fe2O3/SnO2 fibers is proposed. The appealing structural features are favorable for offering a shortened lithium‐ion diffusion length, easy access for the electrolyte and reduced volume variation when used as anodes in LIBs. As a consequence, both single and hybrid oxides show satisfactory reversible capacities (1206 mAh g?1 for Fe2O3 and 1481 mAh g?1 for Fe2O3/SnO2 after 200 cycles at 200 mA g?1) and long lifespans. 相似文献
204.
205.
以Co(NO3)2.6(H2O)、Mg(NO3)2.6(H2O)和Fe(NO3)3.9(H2O)为原料,以NaOH和Na2CO3为沉淀剂采用低过饱和共沉淀法合成了CoMgFe系列的碳酸根水滑石,通过XRD,IR,TG-DTA,等手段对样品进行测试和表征,X-衍射结果显示,其M2 /M3 投料物质的量比为2-4得到的水滑石为理想构型。经焙烧后,发现其复合氧化物对乙醇催化脱水、脱氢反应有一定的活性。 相似文献
206.
207.
The synthesis of ZnO photocatalysts by ultrasound-assisted technique was here investigated. Several experimental parameters including the zinc precursor (acetate, chloride, nitrate), sonication conditions (amplitude, pulse) and post-synthetic thermal treatment (up to 500 °C) were studied. Crystalline ZnO samples were obtained without thermal treatments due to the adopted reactant ratios and synthesis temperature. Sonication plays a major role on the morphological oxide features in terms of particle size and surface area, the latter showing a 20-fold increase with respect to conventional synthesis. Interestingly, 1 and 3 s sonication pulses led to morphological properties similar to continuous sonication. A thermal treatment at moderate temperatures (400–450 °C) promoted the loss of surface hydroxylation and the formation of lattice defects, while higher temperatures were detrimental for the sample morphology. The prepared ZnO was decorated with WO3 particles comparing an ultrasound-assisted technique using 1 s pulses with a conventional approach, giving rise to composites with promoted visible light absorption. Samples were tested towards the photocatalytic degradation of nitrogen oxides (500–1000 ppb) in humidified air under both UV and visible light. By carefully controlling the synthetic procedure, better performance were observed with respect to the commercial benchmark. Samples from ultrasound-assisted syntheses, also in the case of pulsed sonication, showed consistently better results than conventional references, in particular for ZnO-WO3 composites. The composite by ultrasound-assisted synthesis showed > 95% degradation in 180 min and doubled NOx degradation under visible light with respect to the conventional composite. 相似文献
208.
《Current Applied Physics》2020,20(8):931-952
This review accounts, various metal oxide and metal sulfide thin films available for photodegradation of several organic compounds. Due to difficulties in recycling and to avoid rigorous recollection of powder catalysts, the thin film catalyst are gaining rapid attention for photocatalytic applications. The semiconducting thin films are growing as promising photocatalyst for water treatment. This review focuses mainly on the photocatalytic activity of metal oxide thin films in terms of its stability, charge transport and absorption properties. Thin film photocatalyst provides the increased efficiency and cost reduction of device. Furthermore, this review summarizes some key factors regarding the enhancement in photocatalytic performance of thin films. 相似文献
209.
《Current Applied Physics》2020,20(8):953-960
Thickness influence on structural, optical and electrical properties of sputtered indium tin oxide (ITO) with thickness ranging from 60 up to 430 nm films has been studied. At the increase of the film thickness crystallinity degree and grain size increased, whereas tensile structural distortion as well as resistivity decreased. It was observed that a microstructure evolution takes place: the initial amorphous layer evolved in polycrystalline phase, with a grain–subgrain surface morphology. Carrier concentration increased at the increase of the film thickness and a general relationship between electrical characteristics and structural distortion has been found. In thinner films larger tensile distortion allowed to include larger amount of interstitial O and/or Sn atoms in the lattice. An appreciable impact of the thickness was also observed on electro-optical properties in terms of changes in energy gap, resistivity and optical absorption. Silicon heterojunction solar cells have been produced and Jsc as high as 33.0 mA/cm2 has been obtained. 相似文献
210.
本文探讨了CO,CH_4和NH_3在LaNiO_3,La_2NiO_4和LaSrNiO_4三个催化剂上的氧化行为,并得出结论:对于CO氧化,关键步骤在于CO在催化剂表面上的络合活化。Ni ̄(3+)含量越高,越利于CO的络合活化。对于氨氧化,催化反应遵循氧化-还原机理。Ni ̄(3+)是主要的活性离子,晶格氧是主要活性氧种。对于CH_4氧化,催化机理较复杂,只是发现A_2BO_4型氧化物(La_2NiO_4,LaSrNiO_4)比ABO_3型氧化物(LaNiO_3)较利于CH_4的氧化。 相似文献