全文获取类型
收费全文 | 8531篇 |
免费 | 214篇 |
国内免费 | 414篇 |
专业分类
化学 | 1916篇 |
晶体学 | 127篇 |
力学 | 74篇 |
综合类 | 5篇 |
数学 | 83篇 |
物理学 | 6954篇 |
出版年
2024年 | 7篇 |
2023年 | 93篇 |
2022年 | 82篇 |
2021年 | 60篇 |
2020年 | 103篇 |
2019年 | 121篇 |
2018年 | 137篇 |
2017年 | 202篇 |
2016年 | 278篇 |
2015年 | 251篇 |
2014年 | 693篇 |
2013年 | 544篇 |
2012年 | 384篇 |
2011年 | 807篇 |
2010年 | 545篇 |
2009年 | 631篇 |
2008年 | 589篇 |
2007年 | 701篇 |
2006年 | 483篇 |
2005年 | 362篇 |
2004年 | 293篇 |
2003年 | 264篇 |
2002年 | 258篇 |
2001年 | 242篇 |
2000年 | 161篇 |
1999年 | 183篇 |
1998年 | 168篇 |
1997年 | 81篇 |
1996年 | 85篇 |
1995年 | 52篇 |
1994年 | 39篇 |
1993年 | 40篇 |
1992年 | 24篇 |
1991年 | 25篇 |
1990年 | 36篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 26篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 5篇 |
排序方式: 共有9159条查询结果,搜索用时 15 毫秒
31.
Graphite-like carbon nitride (g-C3N4) based heterostrutures has attracted intensive attention due to their prominent photocatalytic performance. Here, we explore the g-C3N4/SnS2 coupling effect on the electronic structures and optical absorption of the proposed g-C3N4/SnS2 heterostructure through performing extensive hybrid functional calculations. The obtained geometric structure, band structures, band edge positions and optical absorptions clearly reveal that the g-C3N4 monolayer weakly couples to SnS2 sheet, and forms a typical van der Waals heterojunction. The g-C3N4/SnS2 heterostructure can effectively harvest visible light, and its valence band maximum and conduction band minimum locate in energetically favorable positions for both water oxidation and reduction reactions. Remarkably, the charge transfer from the g-C3N4 monolayer to SnS2 sheet leads to the built-in interface polarized electric field, which is desirable for the photogenerated carrier separation. The built-in interface polarized electric field as well as the nice band edge alignment implys that the g-C3N4/SnS2 heterostructure is a promising g-C3N4 based water splitting photocatalyst with good performance. 相似文献
32.
Light possesses momentum, and hence, force is exerted on materials if they absorb and/or scatter light. Laser techniques that use optical forces are currently attracting considerable attention. Optical manipulation for trapping, transporting small particles, and measuring the interparticle force is a representative technique. In addition, photoinduced force microscopy is a promising scanning type of microscopy using optical force. Optical force techniques have recently been used in various fields of research, such as molecular bioscience, organic photochemistry, materials engineering, and molecular fluid dynamics. In these techniques, several types of optical forces such as scattering, absorption, and gradient forces play their respective roles. In this article, we summarize the basics of optical forces and present their elementary expressions for using simplified models of light and matter systems. This will help the readers of this Special Issue to understand how different types of forces are distinguished in the basic expressions used for analyzing the optical force phenomena that appear depending on the light geometry and matter systems. After observing simplified cases of scattering and absorption forces, we introduce general formulae for the optical force and then discuss how different components appear in particular cases of laser geometry and materials. 相似文献
33.
Yanqiang Li Dr. Xu Zhang Jieyu Zheng Yang Zhou Weiqi Huang Yipeng Song Han Wang Xianyu Song Prof. Junhua Luo Prof. Sangen Zhao 《Angewandte Chemie (International ed. in English)》2023,62(39):e202304498
Birefringent crystals could modulate the polarization of light and are widely used as polarizers, waveplates, optical isolators, etc. To date, commercial birefringent crystals have been exclusively limited to purely inorganic compounds such as α-BaB2O4 with birefringence of about 0.12. Herein, we report a new hydrogen bonded supramolecular framework, namely, Cd(H2C6N7O3)2⋅8 H2O, which exhibits exceptionally large birefringence up to about 0.60. To the best of our knowledge, the birefringence of Cd(H2C6N7O3)2⋅8 H2O is significantly larger than those of all commercial birefringent crystals and is the largest among hydrogen bonded supramolecular framework crystals. First-principles calculations and structural analyses reveal that the exceptional birefringence is mainly ascribed to strong covalent interactions within (H2C6N7O3)− organic ligands and the perfect coplanarity between them. Given the rich structural diversity and tunability, hydrogen bonded supramolecular frameworks would offer unprecedented opportunities beyond the traditional purely inorganic oxides for birefringent crystals. 相似文献
34.
Dr. Zixuan Xu Zhaoyu Wang Dr. Wei Yao Yanhua Gao Yuxin Li Dr. Huifang Shi Prof. Wei Huang Prof. Zhongfu An 《Angewandte Chemie (International ed. in English)》2023,62(24):e202301564
Dynamic room temperature phosphorescence (RTP) materials have potential applications in optoelectronics, which inevitably suffer from poor processability, flexibility or stretchability. Herein, we report a concise strategy to develop supercooled liquids (SCLs) with dynamic RTP behavior using terminal hydroxyl engineering. The terminal hydroxyls effectively hinder the nucleation process of molecules for the formation of stable SCLs after thermal annealing. Impressively, the SCLs show reversible RTP emission via alternant stimulation by UV light and heat. Photoactivated SCLs have phosphorescent efficiency of 8.50 % and a lifetime of 31.54 ms under ambient conditions. Regarding the dynamic RTP behavior and stretchability of SCLs, we demonstrate the applications in erasable data encryption and patterns on flexible substrates. This finding provides a design principle for obtaining SCLs with RTP and expands the potential applications of RTP materials in flexible optoelectronics. 相似文献
35.
Dr. Bo Zhou Zhenhong Qi Meiqi Dai Chang Xing Prof. Dr. Dongpeng Yan 《Angewandte Chemie (International ed. in English)》2023,62(39):e202309913
Harnessing the potential of thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) is crucial for developing light-emitting diodes (LEDs), lasers, sensors, and many others. However, effective strategies in this domain are still relatively scarce. This study presents a new approach to achieving highly efficient deep-blue TADF (with a PLQY of 25 %) and low-energy orange RTP (with a PLQY of 90 %) through the fabrication of lead-free hybrid halides. This new class of monomeric and dimeric 0D antimony halides can be facilely synthesized using a bottom-up solution process, requiring only a few seconds to minutes, which offer exceptional stability and nontoxicity. By leveraging the highly adaptable molecular arrangement and crystal packing modes, the hybrid antimony halides demonstrate the ability to self-assemble into regular 1D microrod and 2D microplate morphologies. This self-assembly is facilitated by multiple non-covalent interactions between the inorganic cores and organic shells. Notably, these microstructures exhibit outstanding polarized luminescence and function as low-dimensional optical waveguides with remarkably low optical-loss coefficients. Therefore, this work not only presents a pioneering demonstration of deep-blue TADF in hybrid antimony halides, but also introduces 1D and 2D micro/nanostructures that hold promising potential for applications in white LEDs and low-dimensional photonic systems. 相似文献
36.
Éadaoin McCourt Dr. Kane Esien Li Zhenyu Dr. Solveig Felton Dr. Peter Nockemann 《Angewandte Chemie (International ed. in English)》2023,62(7):e201809334
Herein, we report on the preparation of liquid dimeric lanthanide(III)-containing compounds. Starting from the design of dimeric solids, we demonstrate that by tuning of anion and cation structures we can lower the melting points below room temperature, whilst maintaining the dimeric structure. Magnetic measurements could establish the spin-spin interactions of the neighboring lanthanide(III) ions in the liquid state at low temperatures, and matched the interactions of the analogous crystalline solid compounds. 相似文献
37.
《Arabian Journal of Chemistry》2023,16(2):104518
The recycling and recovery of important materials from inexpensive feedstock has now become an intriguing area and vital from commercial and environmental viewpoints. In the present work, extraction of different single phases of alumina (α, γ, θ-Al2O3) having high purity (>99.5 %) from locally available waste beverage cans (~95 % Al) through facile precipitation route calcined at distinct temperatures has been reported. The optimization of process technology was done by a variety of different synthesis parameters, and the production cost was estimated between 84.47-87.45 USD per kg of alumina powder. The as prepared alumina fine particles have been characterized using different sophisticated techniques viz. TG-DTA, WD-XRF, XRD, FT-IR, SEM, DLS-based particle size analysis (PSA) with zeta (ζ) potential measurement and UV–Visible Spectroscopy. X-ray diffractogram confirms the formation of γ-, θ-, and α-alumina at 500–700 °C, 900–1000 °C, and 1200 °C respectively and crystallite size, crystallinity, strain, dislocation density, and specific surface area were measured using major X-ray diffraction peaks which varies with temperature. The SEM studies showed that the as prepared alumina particles were agglomerated, irregular-shaped with particle size (0.23–0.38 µm), pore size, and porosity were calculated from SEM image. ζ-potentials at different pH values as well as isoelectric point (IEP) of α, γ, and θ alumina were calculated in an aqueous medium which changes with temperature. The direct band gap (Eg) energies were found between 4.09 and 5.19 eV of alumina obtained from different calcination temperatures. The synthesized materials can be used in sensors, ceramics, catalysis, and insulation applications. 相似文献
38.
《印度化学会志》2023,100(1):100827
Present paper mainly focuses on the synthesis, characterization polyindole-ZnO nano composites for third order nonlinear optical applications. Polyindole was synthesized through oxidative polymerization technique and its composites were prepared with different ZnO concentration. Structural morphology of the polymer composite was studied using FESEM, XRD and UV Visible spectroscopic technique. Polymer showed broad absorption with absorption maxima of 395 nm. Newly prepared thin films showed excellent nonlinear absorption with very good optical limiting behaviour when it is exposed to He-Ne laser with maximum optical limiting power of 11 mW along with third-order nonlinear susceptibility χ(3) of 2.72 × 10?3 esu. Hence these polymer composites may be potential candidate for optical limiting applications. 相似文献
39.
《印度化学会志》2023,100(3):100928
A new azo β-diketone (NA1) compound is synthesized by coupling reaction of 4-aminoantipyrine with acetylacetone. The NA1 compound is characterized via FTIR, Mass, 1H NMR and 13C NMR spectroscopies. The keto-enol tautomers of the compound electronic structures and energies are investigated using density functional theory (DFT) via B3LYP method/6-311G (d,p) level. The NA1 compound nonlinear optical (NLO) properties are studied via the diffraction patterns (DPs) and the Z-scan where the compound nonlinear index of refraction (NIR), the optical limiting (OLg) property using 473 nm visible, low power, continuous (cw) laser beam are used while the all-optical switching (AOS) property is studied using two laser beams of wavelengths 473 nm and 532 nm. 相似文献
40.
《印度化学会志》2023,100(3):100919
For years, the human race has awaited a more convenient, greener, and largely efficient material for energy conversion and electronic applications. Cu2O thin films produced by spray pyrolysis meet the economic viability and cost requirements, and it is widely assumed that they will lead to the production of functionally viable technologies. The spray pyrolysis method was used to added titanium into copper (I) oxide thin films with a deposition temperature of 200 °C and annealing for 2 h at 200 °C in this study. The Ti-doped Cu2O's optical, surface morphology, and photovoltaic characteristics have all been thoroughly explored. The best characteristics were obtained at 3% Ti doped Cu2O. The near-band emission of Ti-doped Cu2O was moved from 385 nm to 400 nm. The bandgap was reduced from 2.35 to 1.98Ev at 3% Ti doped Cu2O. As a result, Cu2O (Ti)-based solar cells' short circuit current density and open circuit voltage were greatly improved. It has been demonstrated that adding Ti to p-CuO/n-Si solar cells enhances their photovoltaic performance. 相似文献