全文获取类型
收费全文 | 6981篇 |
免费 | 1244篇 |
国内免费 | 205篇 |
专业分类
电工技术 | 47篇 |
综合类 | 350篇 |
化学工业 | 2173篇 |
金属工艺 | 122篇 |
机械仪表 | 780篇 |
建筑科学 | 81篇 |
矿业工程 | 81篇 |
能源动力 | 83篇 |
轻工业 | 1121篇 |
水利工程 | 23篇 |
石油天然气 | 237篇 |
武器工业 | 10篇 |
无线电 | 999篇 |
一般工业技术 | 1053篇 |
冶金工业 | 801篇 |
原子能技术 | 298篇 |
自动化技术 | 171篇 |
出版年
2024年 | 27篇 |
2023年 | 146篇 |
2022年 | 184篇 |
2021年 | 429篇 |
2020年 | 341篇 |
2019年 | 326篇 |
2018年 | 259篇 |
2017年 | 322篇 |
2016年 | 324篇 |
2015年 | 342篇 |
2014年 | 477篇 |
2013年 | 453篇 |
2012年 | 612篇 |
2011年 | 547篇 |
2010年 | 370篇 |
2009年 | 381篇 |
2008年 | 345篇 |
2007年 | 392篇 |
2006年 | 347篇 |
2005年 | 274篇 |
2004年 | 217篇 |
2003年 | 211篇 |
2002年 | 172篇 |
2001年 | 116篇 |
2000年 | 106篇 |
1999年 | 78篇 |
1998年 | 87篇 |
1997年 | 67篇 |
1996年 | 67篇 |
1995年 | 60篇 |
1994年 | 53篇 |
1993年 | 36篇 |
1992年 | 56篇 |
1991年 | 36篇 |
1990年 | 31篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1987年 | 16篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 18篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 3篇 |
1976年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1959年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有8430条查询结果,搜索用时 31 毫秒
131.
Xingwen Tong Zhennan Zhao Lei Hua Yuzhuo Zhang Bowei Xu Yuchao Liu Shouke Yan Zhongjie Ren 《Advanced functional materials》2023,33(43):2305324
Blue conjugated polymers-based OLEDs with both high efficiency and low efficiency roll-off are under big challenge. Herein, a strategy of local conjugation is proposed to construct high-efficiency blue-emitting conjugated polymers, in which the conjugation degree of polymeric backbones is adjusted by inserting different spacers. In this way, the energy level of triplet state and the energy transfer direction of the polymeric main-chains can be effectively regulated. Benefiting from such fine regulation, the prepared alternative copolymers Alt-PB36 with local conjugated main-chains can better suppress the accumulation of long-lived triplet excitons comparing with the complete conjugated polymers. The higher PLQY of Alt-PB36 also verifies the effective energy transfer from the polymeric main-chains to the TADF units. Accordingly, Alt-PB36 based solution-processed OLEDs achieve an EQEmax of 11.6% and a very low efficiency roll-off of 2.8% at 100 cd m−2 and 15.2% at 500 cd m−2. This result represents the best efficiency among blue light-emitting conjugated polymer-based OLEDs so far under high luminance. 相似文献
132.
133.
Janina Wirth Kory K. Green Megan O'Connor Shuang F. Lim 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(6)
Upconverting nanoparticles show potential applications in the field of photovoltaics and array‐based detection devices. While fluorescence enhancement using interference of incident radiation is well known in Stokes‐shift type systems such as fluorescent dyes; the effect of such interference geometry in nonlinear Anti‐Stokes type emission, such as in upconversion rare earth photophysics is demonstrated for the first time. This work describes in detail the influence of the interference modulation on both the excitation (interion energy transfer) and radiative decay with nonradiative decay processes active between emissive levels. These effects are illustrated in the thickness dependence of the decay rate and rise time. Single particle upconverted spectra and time‐resolved measurements show concurrent optimization of the infrared absorption and emission at 540 and 650 nm, with an average enhanced emission of 20 times at λ = 540 and 45 times at λ = 650 nm, dependent on the interference layer thickness and on the excitation intensity. The experimental results are correlated with finite element modeling. Both experiments and calculations show emission enhancement at an interference layer thickness of about 740 ± 20 nm, where such tolerance and the planar design, leads to ease in implementation in applications. 相似文献
134.
Patricia Bondia Rocío Jurado Santiago Casado José M. Domínguez‐Vera Natividad Gálvez Cristina Flors 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(17)
The combination of complementary techniques to characterize materials at the nanoscale is crucial to gain a more complete picture of their structure, a key step to design and fabricate new materials with improved properties and diverse functions. Here it is shown that correlative atomic force microscopy (AFM) and localization‐based super‐resolution microscopy is a useful tool that provides insight into the structure and emissive properties of fluorescent β‐lactoglobulin (βLG) amyloid‐like fibrils. These hybrid materials are made by functionalization of βLG with organic fluorophores and quantum dots, the latter being relevant for the production of 1D inorganic nanostructures templated by self‐assembling peptides. Simultaneous functionalization of βLG fibers by QD655 and QD525 allows for correlative AFM and two‐color super‐resolution fluorescence imaging of these hybrid materials. These experiments allow the combination of information about the topography and number of filaments that compose a fibril, as well as the emissive properties and nanoscale spatial distribution of the attached fluorophores. This study represents an important step forward in the characterization of multifunctionalized hybrid materials, a key challenge in nanoscience. 相似文献
135.
Plasmon Enhanced Fluorescence Based on Porphyrin–Peptoid Hybridized Gold Nanoparticle Platform 下载免费PDF全文
Younghye Kim Boyeong Kang Hyo‐Yong Ahn Jiwon Seo Ki Tae Nam 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(26)
A porphyrin–peptoid‐hybridized silica‐coated gold nanoparticle is developed, which is inspired by the protein–chlorophyll ensemble found in photosynthetic antenna. In the natural antenna, chlorophylls are integrated into dense assemblies that are supported by frameworks of proteins, which ensure optimal pigment arrangement for effective light harvesting. In the subject platform, porphyrins are conjugated to the peptoid helix scaffold in a structurally well‐defined alignments and subsequently immobilized on the surface of nanoparticles. This prevents intermolecular aggregation among porphyrins and allows high resolution analysis of the effect of porphyrin configuration on the optical properties of the system. Interestingly, under the influence of plasmon from the gold nanoparticle core, the fluorescence of porphyrin is enhanced up to 24‐fold at the wavelength where the plasmon resonance matches the porphyrin excitation wavelength. In addition, differences in porphyrin configuration result in spectral modification of their fluorescence emissions. Particularly, the peptoid bearing two porphyrins at a distance of 6 Å shows the most significant alteration in fluorescence. The platform can facilitate extensive studies on the relationship between porphyrin arrangement design and their photophysical interaction in antenna complexes. 相似文献
136.
Photonic Reactions Leading to Fluorescence in a Polymeric System Induced by the Photothermal Effect of Magnetite Nanoparticles Using a 780 nm Multiphoton Laser 下载免费PDF全文
Bum Chul Park Hee‐Dae Kim June Park Yu Jin Kim Young Keun Kim 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(37)
Recently, polymer‐coated magnetite (Fe3O4) nanoparticles (NPs) are extensively studied for applications in therapeutics or diagnostics using photothermal effect. Therefore, it is essential to understand the interactions between Fe3O4 NPs and polymers when optical stimuli are applied. Herein, the photonic reactions of Fe3O4 NPs and polymer composites upon application of a 780 nm multiphoton laser are analyzed. The photonic reactions produce unique results including fluorescence from conformationally changed polymer and low‐temperature phase transformation of Fe3O4 NPs. Typically, π‐conjugated chains are formed, inducing fluorescence through a series of main and side‐chain cleavage reactions of polymers with the aliphatic chain. In addition, fluorescence is detected in the cellular system by photonic reactions between Fe3O4 NPs and biomolecules. After multiphoton laser irradiation, light emission is detected near the intracellular Fe3O4 NPs, and a stronger intensity is observed in large‐sized NPs. 相似文献
137.
138.
139.
Evans Michael G. Al-Shakli Arwa Jenkins Stuart I. Chari Divya M. 《Nano Research》2017,10(8):2881-2890
The development of safe technologies to genetically modify neurons is of great interest in regenerative neurology,for both translational and basic science applications.Such approaches have conventionally been heavily reliant on viral transduction methods,which have safety and production limitations.Magnetofection (magnet-assisted gene transfer using iron oxide nanoparticles as vectors) has emerged as a highly promising non-viral alternative for safe and reproducible genetic modification of neurons.Despite the high potential of this technology,there is an important gap in our knowledge of the safety of this approach,namely,whether it alters neuronal function in adverse ways,such as by altering neuronal excitability and signaling.We have investigated the effects of magnetofection in primary cortical neurons by examining neuronal excitability using the whole cell patch clamp technique.We found no evidence that magnetofection alters the voltage-dependent sodium and potassium ionic currents that underpin excitability.Our study provides important new data supporting magnetofection as a safe technology for bioengineering of neuronal cell populations. 相似文献
140.