全文获取类型
收费全文 | 11837篇 |
免费 | 874篇 |
国内免费 | 626篇 |
专业分类
化学 | 1384篇 |
晶体学 | 44篇 |
力学 | 164篇 |
综合类 | 95篇 |
数学 | 377篇 |
物理学 | 2222篇 |
无线电 | 9051篇 |
出版年
2024年 | 49篇 |
2023年 | 126篇 |
2022年 | 275篇 |
2021年 | 489篇 |
2020年 | 463篇 |
2019年 | 163篇 |
2018年 | 159篇 |
2017年 | 458篇 |
2016年 | 525篇 |
2015年 | 445篇 |
2014年 | 777篇 |
2013年 | 654篇 |
2012年 | 685篇 |
2011年 | 736篇 |
2010年 | 565篇 |
2009年 | 572篇 |
2008年 | 725篇 |
2007年 | 772篇 |
2006年 | 779篇 |
2005年 | 643篇 |
2004年 | 592篇 |
2003年 | 475篇 |
2002年 | 378篇 |
2001年 | 299篇 |
2000年 | 230篇 |
1999年 | 199篇 |
1998年 | 209篇 |
1997年 | 130篇 |
1996年 | 165篇 |
1995年 | 145篇 |
1994年 | 91篇 |
1993年 | 57篇 |
1992年 | 64篇 |
1991年 | 68篇 |
1990年 | 55篇 |
1989年 | 30篇 |
1988年 | 41篇 |
1987年 | 5篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Past and Present of Sol-Gel Science and Technology 总被引:17,自引:0,他引:17
In the last twenty years sol-gel science has undergone a spectacular development. The various stages of the sol-gel process
have been scrutinised in considerable detail and a sound basis for future technological developments established. In the beginning
the studies centred mainly on silica and silicate glasses and were progressively extended to many ceramics and composites.
A turning point was reached with the emergence of ormosils and of organic-inorganic nanocomposites. This opened the gateway
to whole classes of new materials. The present studies show a definite tendency towards very specialised high-tech applications. 相似文献
102.
Chouhaid Nasr Prashant V. Kamat Surat Hotchandani 《Journal of Electroanalytical Chemistry》1997,420(1-2)
A photoelectrochemical cell with a coupled SnO2|CdSe nanocrystalline semiconductor electrode has been prepared by sequential deposition of SnO2 and CdSe films onto an optically transparent electrode (OTE), and its photoelectrochemical behavior has been studied. The results show that the coupling of CdSe with SnO2 leads to an improvement in the performance of OTE|SnO2|CdSe over OTE|CdSe cells in terms of increased incident photon-to-current conversion efficiency, increased stability and smaller reversal of current. The favorable positioning of the energy bands of SnO2 and CdSe is responsible for the above observations. Various photoelectrochemical parameters of the OTE|SnO2|CdSe cell obtained for an incident light power of 0.31 mW cm−2 at 470nm, are as follows: Isc ≈ 25–30 μA cm−2, Voc ≈ 0.5–0.6 V, ƒƒ = 0.47 and a power conversion efficiency of about 2.25%. 相似文献
103.
104.
《Mendeleev Communications》2021,31(5):593-604
In this focus overview, the main types and directions of engineering, methods and techniques of intensification of chemical process systems (CPS) and process optimization of energy- and resource-efficient processes for the representative production of titanium compounds, mining waste processing systems, electrochemical coating technologies, combined technologies for the treatment of industrial effluents and energy-and resource-efficient technologies for cleaning soils from petroleum and chemical pollution products are reviewed. The following issues have been discussed: methods of complex assessment of production energy efficiency and software and information support for automated synthesis of optimal energy-efficient regenerative heat exchange systems using pinch analysis; methods and algorithms for fractal-statistical characteristics analysis of nonstationary gas flows in complex gas pipelines; methods of ecological and economic optimization of production, infrastructure supply chains; methods for assessing and preventing the dangerous environmental impact assessment of chemical pollution; organization and logistics management of business processes engineering for improving the energy efficiency of plants; engineering of problem oriented computer systems, heuristic-computational models and algorithms for intelligent integrated logistics support of the equipment life cycle; engineering developments in the field of digital transformation of energy-efficient CPS and technological production systems; application of methods for optimizing reliability factors optimization, digitalized risk and safety management in the engineering of energy- and resource efficient CPS. 相似文献
105.
106.
Nanomaterials with localized surface plasmon resonance (LSPR) locating in the near-infrared region have broad application prospects in the field of biomedicine. However, the biggest problem that limits the biomedical application of such nanomaterials lies in two aspects: First, the potential long-term in vivo toxicity caused by the metabolism of many nanomaterials with LSPR effect; Second, most of current nanomaterials with LSPR effect are difficult to achieve LSPR wavelength tunability in the near-infrared region to adapt to different biomedical applications. Copper selenide nanomaterials are composed of selenium and copper, which are necessary nutrient elements for human life. Because of the active and flexible chemical properties of selenium and copper, copper selenide nanomaterials can not only be effectively degraded and utilized in human body, but also be endowed with various physicochemical properties by chemical modification or doping. Recently, copper selenide nanomaterials have shown unique properties such as LSPR in the near-infrared region, making them attractive for near-infrared thermal ablation, photoacoustic imaging, disease marker detection, multimode imaging, and so on. Currently, to the best of our knowledge, there is no review on the LSPR properties of copper selenide nanomaterials and its biomedical applications. This review first discusses the relationship between the physicochemical properties and the LSPR of copper selenide nanomaterials and then summarizes the latest progress in the application of copper selenide nanomaterials in biological detection, diagnosis, and treatment of diseases. In addition, the advantages, and prospects of copper selenide nanomaterials in biomedicine are also highlighted. 相似文献
107.
108.
109.
Aycha Jellali Slim Elleuch Besma Hamdi Ridha Zouari 《Journal of Saudi Chemical Society》2019,23(5):600-611
In this work, a new hybrid material (C5H6N2Cl)2[FeCl4].Cl abbreviated (CAP)2[FeCl4].Cl was prepared using room temperature slow evaporation technique. The X-ray diffraction analysis revealed that the compound is crystallized in the centrosymmetric space group P21/c of the monoclinic system. The crystallographic network consists of an Fe(III) ion located on an inversion center and coordinated by four chlorine, isolated Cl– and two (CAP)+ protonated cations linked by N–H...Cl and C–H...Cl hydrogen bonds to form a zero-dimensional network. Hirshfeld surface analysis was used to analyze intermolecular interactions present in the crystal structure. The vibrational properties were inspected by means of Infra-Red absorption and Raman diffusion spectroscopy techniques. In addition, theoretical calculations based on the DFT/B3LYP/LanL2DZ method and the time-dependent density functional theory (TD–DFT) were performed in order to gain more information and help in the examination of over-all properties of the title compound. Good and interesting experimental findings were presented and good consistency was found with the calculated results. 相似文献
110.
口腔癌系头颈部癌,癌组织均位于口腔内,其非侵入性早期诊断是减少该病死亡的有效手段.唾液系口腔癌变相关物质首先释放进入的体液,取材方便,安全无创,是口腔癌普查筛选、早期诊断的首选指标.本文对唾液肿瘤生物标志物的种类、目前国内外常用的检测方法进行概述,重点阐述新型电化学生物传感方法在口腔癌相关唾液肿瘤生物标志物检测方面的相关应用及其最新研究进展.并对口腔癌相关唾液肿瘤生物标志物电化学传感技术的未来发展方向提出展望,拟为其深入研究与应用提供参考. 相似文献