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排序方式: 共有244条查询结果,搜索用时 24 毫秒
1.
通过低温溶胶-凝胶技术结合旋涂法制备了掺偶氮苯二氧化钛基有机-无机复合薄膜。研究了不同热处理温度对复合薄膜的表面形貌、传输模式、折射率与厚度和光化学结构特性的影响。结果表明:该复合薄膜在低于300℃的热处理温度时表面光滑致密、折射率可调,是良好的光波导材料。通过测试样品在365 nm紫外光和450 nm可见光照射下的吸光度,研究了复合薄膜的光开关性能。在研究周期内,光开关性能良好,具有一定的抗疲劳性,在光电子学领域具有重要的应用价值。  相似文献   
2.
利用可逆的光异构化捕获、转换、储存和以热的形式释放太阳能的偶氮苯光致异构储能材料成为目前研究的主要焦点之一.近年来,偶氮苯在光储能方面取得了一定的研究成果.介绍偶氮苯光致异构储能材料的储能机理及主要性能指标的基础上,重点介绍了偶氮苯光致异构储能材料半衰期、能量密度和可见光储能的研究现状,分析了各偶氮苯用于储能的优劣势,展望了偶氮苯光致异构储能材料在固态膜中的研究方向和应用前景.  相似文献   
3.
Photoswitchable lipids are emerging tools for the precise manipulation and study of lipid function. They can modulate many aspects of membrane biophysics, including permeability, fluidity, lipid mobility and domain formation. They are also very useful in lipid physiology and enable optical control of a wide array of lipid receptors, such as ion channels, G protein-coupled receptors, nuclear hormone receptors, and enzymes that translocate to membranes. Enzymes involved in lipid metabolism often process them in a light-dependent fashion. Photoswitchable lipids complement other functionalized lipids widely used in lipid chemical biology, including isotope-labeled lipids (lipidomics), fluorescent lipids (imaging), bifunctional lipids (lipid–protein crosslinking), photocaged lipids (photopharmacology), and other labeled variants.  相似文献   
4.
A low‐powered and highly selective photomechanical sensor system mimicking stomata in the epidermis of leaves harvested from nature is demonstrated. This device uses a light‐responsive composite consisting of 4‐amino‐1,1′‐azobenzene‐3,4′‐disulfonic acid monosodium salt (AZO) and poly(diallyldimethylammonium chloride) (PDDA) coated on a membrane with tens of nanometer‐size pores. The ionic current change through the pore channels as a function of pore size variation is then measured. The tran–cis isomerism of AZO–PDDA during light irradiation and the operation mechanism of photomechanical ion channel sensor are discussed and analyzed using UV–vis spectroscopy and atomic force microscopy analysis. It presents the discriminative current levels to the different light wavelengths. The response time of the photoreceptor is about 0.2 s and it consumes very low operating power (≈15 nW) at 0.1 V bias. In addition, it is found that the change of the pore diameter during the light irradiation is due to the photomechanical effect, which is capable of distinguishing light intensity and wavelength.  相似文献   
5.
It is well known that irradiation of azobenzene polymer films between 490 and 530 nm results in alignment of molecules perpendicular to the polarization of the incident beam. I have recently found that irradiation of amorphous azobenzene polymers with linearly polarized light at wavelengths between 560 and 630 nm, where the absorption is minimal, results in a possible uniaxial hedgehog arrangement of the molecules. Experiments performed with a dye laser, which can be tuned continuously between 560 and 630 nm, are described. Not only azobenzene but also another photosensitive molecule, bacteriorhodopsin, seems to exhibit this behavior.  相似文献   
6.
A novel method for synthesizing and photopatterning colloidal crystals via light-responsive DNA is developed. These crystals are composed of 10–30 nm gold nanoparticles interconnected with azobenzene-modified DNA strands. The photoisomerization of the azobenzene molecules leads to reversible assembly and disassembly of the base-centered cubic (bcc) and face-centered cubic (fcc) crystalline nanoparticle lattices. In addition, UV light is used as a trigger to selectively remove nanoparticles on centimeter-scale thin films of colloidal crystals, allowing them to be photopatterned into preconceived shapes. The design of the azobenzene-modified linking DNA is critical and involves complementary strands, with azobenzene moieties deliberately staggered between the bases that define the complementary code. This results in a tunable wavelength-dependent melting temperature (Tm) window (4.5–15 °C) and one suitable for affecting the desired transformations. In addition to the isomeric state of the azobenzene groups, the size of the particles can be used to modulate the Tm window over which these structures are light-responsive.  相似文献   
7.
Beyond their colorful appearances and versatile geometries, flowers can self‐shape‐morph by adapting to environmental changes. Such responses are often regulated by a delicate interplay between different stimuli such as temperature, light, and humidity, giving rise to the beauty and complexity of the plant kingdom. Nature inspires scientists to realize artificial systems that mimic their natural counterparts in function, flexibility, and adaptation. Yet, many of the artificial systems demonstrated to date fail to mimic the adaptive functions, due to the lack of multi‐responsivity and sophisticated control over deformation directionality. Herein, a new class of liquid‐crystal‐network (LCN) photoactuators whose response is controlled by delicate interplay between light and humidity is presented. Using a novel deformation mechanism in LCNs, humidity‐gated photoactuation, an artificial nocturnal flower is devised that is closed under daylight conditions when the humidity level is low and/or the light level is high, while it opens in the dark when the humidity level is high. The humidity‐gated photoactuators can be fueled with lower light intensities than conventional photothermal LCN actuators. This, combined with facile control over the speed, geometry, and directionality of movements, renders the “nocturnal actuator” promising for smart and adaptive bioinspired microrobotics.  相似文献   
8.
Remote transport of material is an utmost useful, but challenging, property expanding the design possibilities of many applications such as microfluidics or robotics where species can be carried without interfering with its environment. Nature has solved the problem of transport in e.g., the respiratory system by a concerted motion of cilia. This study addresses a new method to fabricate an array of small parallel fibers acting as cilia placed side by side on a substrate. The fibers consist of a crosslinked liquid crystal main chain polymer functionalized with coreactant azobenzene molecules. The fibers bend toward a light source in a concerted manner. When placed in a liquid, the cooperative bending motion of the fibers creates a flow able to efficiently carry objects. The proposed fabrication process of the fibers is scalable to large area and requires an optimized rheology which is achieved by converting low molecular weight reactive liquid crystal acrylate monomers to oligomers using a multiplication of the monomeric units by the Michael addition reaction with dithiol. The oligomer properties and the elasticity of the fibers are adjusted by changing the thiol spacer leading to optimized manufacturing and maximized optical response.  相似文献   
9.
The design and synthesis of a new azobenzene-based methacrylate monomer (Azo-IEM) was demonstrated, and its polymerization behavior during reversible addition-fragmentation chain transfer (RAFT) polymerization was investigated. Well-defined homopolymer and amphiphilic block copolymer containing Azo-IEM monomeric units were successfully prepared as evidenced by NMR and GPC analysis. Moreover, the photo-triggered reversible isomerization of polymer products in selected solvents was investigated. Finally, TEM analysis showed that there were significant differences in the nanoparticle morphologies when the block copolymer samples were irradiated with different wavelengths of light (i.e., UV and visible). The size and shapes of the p(HEMA-b-Azo-IEM) polymer capable of transitions upon changes in Vis/UV light exposure which prepared from MeOH/CHCl3 mixture solvent. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47870.  相似文献   
10.
以4-(4′-硝基偶氮苯)-1-萘酚、4-氯正丁醇和3-噻吩乙酸为原料,通过脱氯化氢反应、酯化反应和化学氧化聚合反应,制备了具有推拉电子结构的侧链含偶氮苯发色团的聚噻吩衍生物(PATh4)。采用红外光谱(FT-IR)、紫外光谱(UV-Vis)、凝胶渗透色谱和核磁共振(1H-NMR)对PATh4的结构进行了表征。研究表明,PATh4的热稳定性较好,起始分解温度约为204℃,玻璃化转变温度约为75℃;其X射线衍射(XRD)曲线呈现宽的漫反射峰,说明PATh4是非晶态结构;PATh4具有良好的光致发光性能,在二甲基亚砜中其荧光光谱呈现两个明显的发射峰,分别位于540 nm和698 nm,对应的荧光寿命分别为9.5×10-10s和5.7×10-9s。  相似文献   
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