全文获取类型
收费全文 | 155730篇 |
免费 | 36377篇 |
国内免费 | 12546篇 |
专业分类
化学 | 128255篇 |
晶体学 | 1419篇 |
力学 | 9445篇 |
综合类 | 748篇 |
数学 | 16271篇 |
物理学 | 48515篇 |
出版年
2024年 | 383篇 |
2023年 | 5422篇 |
2022年 | 3829篇 |
2021年 | 6211篇 |
2020年 | 8686篇 |
2019年 | 6675篇 |
2018年 | 5946篇 |
2017年 | 4323篇 |
2016年 | 10669篇 |
2015年 | 10354篇 |
2014年 | 11173篇 |
2013年 | 13486篇 |
2012年 | 13740篇 |
2011年 | 12533篇 |
2010年 | 10758篇 |
2009年 | 10448篇 |
2008年 | 8876篇 |
2007年 | 7907篇 |
2006年 | 6712篇 |
2005年 | 5635篇 |
2004年 | 4204篇 |
2003年 | 3330篇 |
2002年 | 2990篇 |
2001年 | 2488篇 |
2000年 | 2249篇 |
1999年 | 2649篇 |
1998年 | 2339篇 |
1997年 | 2233篇 |
1996年 | 2385篇 |
1995年 | 2015篇 |
1994年 | 1873篇 |
1993年 | 1645篇 |
1992年 | 1365篇 |
1991年 | 1274篇 |
1990年 | 1030篇 |
1989年 | 777篇 |
1988年 | 667篇 |
1987年 | 543篇 |
1986年 | 501篇 |
1985年 | 450篇 |
1984年 | 351篇 |
1983年 | 265篇 |
1982年 | 255篇 |
1981年 | 210篇 |
1980年 | 188篇 |
1977年 | 191篇 |
1976年 | 218篇 |
1975年 | 217篇 |
1974年 | 239篇 |
1970年 | 220篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
101.
We present the fabrication of core-shell-satellite Au@SiO2-Pt nanostructures and demonstrate that LSPR excitation of the core Au nanoparticle can induce plasmon coupling effect to initiate photocatalytic hydrogen generation from decomposition of formic acid. Further studies suggest that the plasmon coupling effect induces a strong local electric field between the Au core and Pt nanoparticles on the SiO2 shell, which enables creation of hot electrons on the non-plasmonic-active Pt nanoparticles to participate hydrogen evolution reaction on the Pt surface. In addition, small SiO2 shell thickness is required in order to obtain a strong plamon coupling effect and achieve efficient photocatalytic activities for hydrogen generation. 相似文献
102.
Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) have been deemed as clean and sustainable strategies to solve the energy crisis and environmental problems. Various catalysts have been developed to promote the process of HER and OER. Among them, two-dimensional covalent organic frameworks (2D COFs) have received great attention due to their diverse and designable structure. In this minireview, we mainly summarize the diverse linkages of 2D COFs and strategies for enhancing the catalytic performance of 2D COFs for HER and OER, such as introducing active building blocks, metal ions and tailored linkages. Furthermore, a brief outlook for the development directions of COFs in the field of HER and OER is provided, expecting to stimulate new opportunities in future research. 相似文献
103.
Natural products with a variety of pharmacological effects are important sources for commercial drugs, and it is very crucial to develop effective techniques to selectively extract and isolate bioactive natural components from the plants against the background of sustainable development. Ionic liquids (ILs) are a kind of designable material with unique physicochemical properties, including good thermal stability, negligible vapor pressure, good solvation ability, etc. ILs have already been used in pharmaceuticals for extraction, purification, drug delivery, etc. It has been reported that multi-interactions, like hydrogen bonding, hydrophobic interactions, play important roles in the extraction of bioactive components from the plants. In this review, recent progress in the understanding of scientific essence of hydrogen bonding, the special interaction, in ILs was summarized. The extraction of various natural products, one important area in pharmaceutical, by conventional and functional ILs as well as the specific roles of multi-interactions in this process were also reviewed. Moreover, problems existing in bioactive compound extraction by ILs and the future developing trends of this area are given, which might be helpful for scientists, especially beginners, in this field. 相似文献
104.
Yuwei Wang Jia-Jun Yan Shengnan Hu Prof. David James Young Prof. Hong-Xi Li Prof. Zhi-Gang Ren 《化学:亚洲杂志》2021,16(18):2681-2686
A photoluminescent bimetallic cluster [Ag10Cu6(bdppthi)2(C≡CPh)12(MeOH)2(H2O)](ClO4)4 ( 1 , bdppthi=N,N’-bis(diphenylphosphanylmethyl)-tetrahydroimidazole} was synthesized from the PNNP type ligand bdppthi generated in-situ. Upon excitation at 365 nm, 1 exhibited strong phosphorescent emission at 630 nm, which was selectively quenched by NH3 in air or water. The sensing of NH3 was rapid and recoverable, with detection limits of 53 ppm (v/v) in N2 and 21 μmol/L (0.36 ppm, w/w) for NH3 ⋅ H2O in water. Cluster 1 could potentially serve as a bifunctional chemical sensor for the efficient detection of ammonia in waste-gas and waste-water. 相似文献
105.
Du Yongbo Yu Pengfei Wang Junxiong Zhang Jinping Wang Chang’an Che Defu 《Journal of Thermal Analysis and Calorimetry》2021,143(1):327-334
Journal of Thermal Analysis and Calorimetry - Coal O2/CO2 combustion is a promising carbon capture and storage technology for coal-fired power plant. Char consumption rate prediction is essential... 相似文献
106.
107.
Wang Dong Ming Fei Song Xue-Ke Ye Liu Chen Jing-Ling 《The European Physical Journal C - Particles and Fields》2020,80(8):1-16
The European Physical Journal C - We study the isentropic evolution of the matter produced in relativistic heavy-ion collisions for various values of the entropy-per-baryon ratio of interest for... 相似文献
108.
Timm Bergholz Dr. Benjamin Oelkers Dr. Benedikt Huber Prof. Bernhard Roling Prof. Dr. Jörg Sundermeyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2613-2620
New salts based on imidazolium, pyrrolidinium, phosphonium, guanidinium, and ammonium cations together with the 5‐cyanotetrazolide anion [C2N5]? are reported. Depending on the nature of cation–anion interactions, characterized by XRD, the ionic liquids (ILs) have a low viscosity and are liquid at room temperature or have higher melting temperatures. Thermogravimetric analysis, cyclic voltammetry, viscosimetry, and impedance spectroscopy display a thermal stability up to 230 °C, an electrochemical window of 4.5 V, a viscosity of 25 mPa s at 20 °C, and an ionic conductivity of 5.4 mS cm?1 at 20 °C for the IL 1‐butyl‐1‐methylpyrrolidinium 5‐cyanotetrazolide [BMPyr][C2N5]. On the basis of these results, the synthesized compounds are promising electrolytes for lithium‐ion batteries. 相似文献
109.
110.
Functional Carbazole Liquid‐Crystal Block Codendrimers with Optical and Electronic Properties 下载免费PDF全文
Ismael Gracia Beatriz Feringán Prof. José Luis Serrano Dr. Roberto Termine Dr. Attilio Golemme Dr. Ana Omenat Prof. Joaquín Barberá 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):1359-1369
The synthesis and characterisation of a family of block codendrimers consisting of highly versatile mesogenic and carbazole‐containing 2,2‐bis(hydroxymethyl)propionic acid (bis‐MPA) dendrons are reported. The liquid‐crystal behaviour was investigated by means of differential scanning calorimetry, polarised‐light optical microscopy and X‐ray diffraction. Depending on the chemical structure of the constituent dendrons, the codendrimers show lamellar or columnar mesophases. On the basis of the experimental results, models both at the molecular level and in the mesophase are proposed. The physical properties of the block codendrimers derived from the presence of the carbazole moiety in their structure were investigated: photoluminescence in solution and in the mesophase, electrochemical behaviour and hole transport. Electrodeposition of carbazole dendrons afforded a globular supramolecular conformation in which the mesogenic molecular side plays a key role. 相似文献