全文获取类型
收费全文 | 1167篇 |
免费 | 80篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 2篇 |
综合类 | 6篇 |
化学工业 | 581篇 |
金属工艺 | 20篇 |
机械仪表 | 6篇 |
建筑科学 | 2篇 |
能源动力 | 48篇 |
轻工业 | 161篇 |
石油天然气 | 4篇 |
无线电 | 191篇 |
一般工业技术 | 225篇 |
冶金工业 | 1篇 |
原子能技术 | 1篇 |
自动化技术 | 4篇 |
出版年
2024年 | 5篇 |
2023年 | 12篇 |
2022年 | 9篇 |
2021年 | 21篇 |
2020年 | 17篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 48篇 |
2016年 | 38篇 |
2015年 | 47篇 |
2014年 | 60篇 |
2013年 | 65篇 |
2012年 | 70篇 |
2011年 | 91篇 |
2010年 | 71篇 |
2009年 | 97篇 |
2008年 | 94篇 |
2007年 | 108篇 |
2006年 | 69篇 |
2005年 | 59篇 |
2004年 | 56篇 |
2003年 | 36篇 |
2002年 | 39篇 |
2001年 | 29篇 |
2000年 | 23篇 |
1999年 | 11篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 4篇 |
排序方式: 共有1252条查询结果,搜索用时 15 毫秒
1.
Yan He Kangren Kong Zhengxi Guo Weifeng Fang Zaiqiang Ma Haihua Pan Ruikang Tang Zhaoming Liu 《Advanced functional materials》2021,31(26):2101291
Sensitivity and multi-directional motivation are major two factors for developing optimized humidity-response materials, which are promising for sensing, energy production, etc. Organic functional groups are commonly used as the water sensitive units through hydrogen bond interactions with water molecules in actuators. The multi-coordination ability of inorganic ions implies that the inorganic ionic compounds are potentially superior water sensitive units. However, the particle forms of inorganic ionic compounds produced by classical nucleation limit the number of exposed ions to interact with water. Recent progress on the inorganic ionic oligomers has broken through the limitation of classical nucleation, and realized the molecular-scaled incorporation of inorganic ionic compounds into an organic matrix. Here, the incorporation of hydrophilic calcium carbonate ionic oligomers into hydrophobic poly(vinylidene fluoride) (PVDF) is demonstrated. The ultra-small calcium carbonate oligomers within a PVDF film endow it with an ultra-sensitive, reversible, and bidirectional response. The motivation ability is superior to other bidirectional humidity-actuators at present, which realizes self-motivation on an ice surface, converting the chemical potential energy of the humidity gradient from ice to kinetic energy. 相似文献
2.
Karishma Tiwari Pulak Sarkar Solagna Modak Harwinder Singh Sumit Kumar Pramanik Santanu Karan Amitava Das 《Advanced materials (Deerfield Beach, Fla.)》2020,32(8):1905621
Separation membranes with higher molecular weight cut-offs are needed to separate ions and small molecules from a mixed feed. The molecular sieving phenomenon can be utilized to separate smaller species with well-defined dimensions from a mixture. Here, the formation of freestanding polyimine nanofilms with thicknesses down to ≈14 nm synthesized via self-assembly of pre-synthesized imine oligomers is reported. Nanofilms are fabricated at the water–xylene interface followed by reversible condensation of polymerization according to the Pieranski theory. Polyimine nanofilm composite membranes are made via transferring the freestanding nanofilm onto ultrafiltration supports. High water permeance of 49.5 L m-2 h−1 bar−1 is achieved with a complete rejection of brilliant blue-R (BBR; molecular weight = 825 g mol−1) and no more than 10% rejection of monovalent and divalent salts. However, for a mixed feed of BBR dye and monovalent salt, the salt rejection is increased to ≈18%. Membranes are also capable of separating small dyes (e.g., methyl orange; MO; molecular weight = 327 g mol−1) from a mixed feed of BBR and MO. Considering a thickness of ≈14 nm and its separation efficiency, the present membrane has significance in separation processes. 相似文献
3.
4.
M. Knaapila R. Stepanyan B.P. Lyons M. Torkkeli A.P. Monkman 《Advanced functional materials》2006,16(5):599-609
This account highlights recent progress towards understanding the complex hierarchical levels of solid‐state structure in a prototypical helical hairy‐rod polyfluorene, poly[9,9‐bis(2‐ethylhexyl)fluorene‐2,7‐diyl] (or PF2/6). This branched‐side‐chain containing polyfluorene undergoes a systematic intermolecular self‐assembly and liquid‐crystalline phase behavior in combination with uniaxial and biaxial alignment. The latter processes yield full three‐dimensional orientation of the crystallites and polymer chains. Also reviewed are the impact of the molecular structure and phase behavior on surface morphology, anisotropic film formation, and, ultimately, the overall impact of these physical attributes on optical constants. This particular polyfluorene also represents a model system for demonstrating the applicability of mean‐field theory in detailing the self‐organization of aligned hairy‐rod block‐copolymer systems. These results of PF2/6 are compared to those of other archetypical π‐conjugated hairy‐rod polymers. General guidelines of how molecular weight influences nanostructure, phase behavior, alignment, and surface morphology are given. 相似文献
5.
The present study deals with effect of the type and chemical character of incorporated polyester/polyether blocks on the hydrolytic stability of crosslinked polyurethane oligomers. Diffusion parameters of the investigated polyurethane oligomers, giving information concerning chemical changes taking place in neutral, basic and acidic aqueous environments, have also been determined. 相似文献
6.
7.
The effect of side chain length of π-conjugated poly(9,9-dialkylfluorene)s has been studied in semi-dilute (10 mg/mL) toluene solutions using small-angle neutron scattering (SANS) and 1H and 2H NMR spectroscopies. Under these conditions, SANS data indicate that poly(9,9-dinonylfluorene) and poly(9,9-dioctylfluorene) are dissolved down to the molecule level and appear as elongated one-dimensional chains (length >20-30 nm). In contrast, the shorter side chain polymers exhibit a self-association so that poly(9,9-diheptylfluorene) forms thin sheet-like (∼1 nm) and poly(9,9-dihexylfluorene) thin (∼1 nm) and thick sheet-like (>6 nm) aggregates. 1H NMR data, together with the density functional theory (DFT) calculations, however, show that this occurs without changes in the conformation of the polymer backbone. 相似文献
8.
S.K. Lee D.‐H. Hwang B.‐J. Jung N.S. Cho J. Lee J.‐D. Lee H.‐K. Shim 《Advanced functional materials》2005,15(10):1647-1655
By using Ni0‐mediated polymerization, we have systematically synthesized a series of fluorene‐based copolymers composed of blue‐, green‐, and red‐light‐emitting comonomers with a view to producing polymers with white‐light emission. 2,7‐Dibromo‐9,9‐dihexylfluorene, {4‐(2‐[2,5‐dibromo‐4‐{2‐(4‐diphenylamino‐phenyl)‐vinyl}‐phenyl]‐vinyl)‐phenyl}‐diphenylamine (DTPA), and 2‐{2‐(2‐[4‐{bis(4‐bromo‐phenyl)amino}‐phenyl]‐vinyl)‐6‐tert‐butyl‐pyran‐4‐ylidene}‐malononitrile (TPDCM) were used as the blue‐, green‐, and red‐light‐emitting comonomers, respectively. It was found that the emission spectra of the resulting copolymers could easily be tuned by varying their DTPA and TPDCM content. Thus with the appropriate red/green/blue (RGB) unit ratio, we were able to obtain white‐light emission from these copolymers. A white‐light‐emitting diode using the polyfluorene copolymer containing 3 % green‐emitting DTPA and 2 % red‐emitting TPDCM (PG3R2) with a structure of indium tin oxide/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonic acid)/PG3R2/Ca/Al was found to exhibit a maximum brightness of 820 cd m–2 at 11 V with Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.35), which are close to the standard CIE coordinates for white‐light emission (0.33,0.33). 相似文献
9.
Jean-Christophe Autrique 《Computers & Structures》2007,85(9):518-525
This work is devoted to a study of a conjugated infinite element method for Helmholtz problems in exterior domains. A formulation of this method with Lagrange multipliers defined on (semi-)infinite space is presented and analyzed in a domain decomposition context. The implementation aspects of this method in a parallel industrial acoustic software (SYSNOISE) are described in details. Numerical results show the computational efficiency of this method on acoustic scattering problems. 相似文献
10.
Joonyoung Park Sung-Hwan Han S. Senthilarasu Soo-Hyoung Lee 《Solar Energy Materials & Solar Cells》2007,91(8):751-753
Recent studies have reported that a thin interlayer between poly(3, 4-ethylene dioxythiophene)-poly(styrene sulfonic acid) (PEDOT: PSS) and an emissive polymer layer leads to a large increase in the performances of polymer light-emitting diodes (PLEDs) by preventing significant quenching of the radiative excitons at the PEDOT: PSS interface; therefore, acting as an efficient exciton-blocking layer. Using the similar idea, a thin interlayer was fabricated between PEDOT: PSS and the active layer of conjugated polymers/methanofullerene composites in a plastic solar cell. The interlayer consisted of a poly(fluorene)-based hole transporter spin-coated directly on top of the PEDOT: PSS layer. The devices with the interlayer exhibited a higher efficiency than in those without the interlayer. 相似文献