全文获取类型
收费全文 | 21284篇 |
免费 | 1778篇 |
国内免费 | 928篇 |
专业分类
电工技术 | 1171篇 |
技术理论 | 2篇 |
综合类 | 1366篇 |
化学工业 | 3558篇 |
金属工艺 | 1158篇 |
机械仪表 | 1370篇 |
建筑科学 | 1929篇 |
矿业工程 | 745篇 |
能源动力 | 580篇 |
轻工业 | 1219篇 |
水利工程 | 345篇 |
石油天然气 | 1494篇 |
武器工业 | 121篇 |
无线电 | 2209篇 |
一般工业技术 | 2578篇 |
冶金工业 | 1041篇 |
原子能技术 | 231篇 |
自动化技术 | 2873篇 |
出版年
2024年 | 78篇 |
2023年 | 407篇 |
2022年 | 570篇 |
2021年 | 871篇 |
2020年 | 724篇 |
2019年 | 608篇 |
2018年 | 657篇 |
2017年 | 737篇 |
2016年 | 629篇 |
2015年 | 819篇 |
2014年 | 1118篇 |
2013年 | 1218篇 |
2012年 | 1396篇 |
2011年 | 1435篇 |
2010年 | 1300篇 |
2009年 | 1165篇 |
2008年 | 1157篇 |
2007年 | 1116篇 |
2006年 | 1173篇 |
2005年 | 1109篇 |
2004年 | 655篇 |
2003年 | 571篇 |
2002年 | 510篇 |
2001年 | 478篇 |
2000年 | 445篇 |
1999年 | 589篇 |
1998年 | 459篇 |
1997年 | 392篇 |
1996年 | 358篇 |
1995年 | 312篇 |
1994年 | 239篇 |
1993年 | 140篇 |
1992年 | 128篇 |
1991年 | 113篇 |
1990年 | 87篇 |
1989年 | 69篇 |
1988年 | 53篇 |
1987年 | 28篇 |
1986年 | 30篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Polyacrylate nanocapsules loaded with lilial (PNLs) were prepared via miniemulsion polymerization. Then, the PNLs were applied directly to leather. The influence of the contents of the surfactant and lilial and the stirring speed on the mean size and fragrance loading capacity of the PNLs was investigated in detail. The microstructure of the PNLs was determined by dynamic light scattering (DLS), transmission electron nicroscopy (TEM), Fourier transform infrared (FTIR) spectrometry, and thermogravimetric analysis (TGA). The sustained release properties of the leather finished by PNLs were characterized by scanning electron microscopy (SEM) and gas chromatography with a flame ionization detector (GC‐FID). DLS showed that the mean size of the PNLs was 67.78 nm, and the polydispersity index was 0.076. TEM illustrated that the size of the spherical PNL varied in the range 30–80 nm. FTIR spectroscopy showed that lilial was encapsulated into the polyacrylate nanocapsules. TGA illustrated that the fragrance loading ratio of the nanocapsules reached 36.83%. SEM and GC‐FID indicated that the leather finished by the PNLs had better flexing endurance than that finished by lilial emulsion. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40182. 相似文献
992.
Poly(vinylidene fluoride) (PVDF) ultrafiltration membranes were prepared by immersion precipitation method using poly(hydroxyethyl methacrylate)-block-poly(methyl methacrylate) grafted silica (PHEMA-b-PMMA@SiO2) nanoparticles as additives. The hybrid nanoparticles were synthesized by the surface initiated atom transfer radical polymerization (SI-ATRP), and they were characterized in detail by FT-IR, TEM, DLS and GPC. Results confirm that core–shell structure is formed after grafting PHEMA-b-PMMA brushes on the silica nanoparticles. Their average hydrodynamic diameter also increases with the prolongation of grafting time. After blending PVDF with the hybrid silica nanoparticles, the composite PVDF membranes exhibit high porosity and improved water permeation. Especially, when the molecular weight is 1.73 × 105 g/mol for PHEMA-b-PMMA on the hybrid nanoparticles, the water flux of the PVDF composite membrane is 2.5 times than that of the control PVDF membrane, while the rejection to bovine serum albumin (BSA) remains at a high level (>90%). In addition, all the composite PVDF membranes show lower BSA adsorption and larger water flux recovery ratio than the control PVDF membrane. The improvement of membrane performance is attributed to the good hydrophilicity of PHEMA-b-PMMA@SiO2 nanoparticles. Our results suggest that PHEMA-b-PMMA@SiO2 nanoparticles with moderate molecular weight of PHEMA-b-PMMA are suitable for the property optimization of PVDF-based composite membranes. 相似文献
993.
994.
Jianzhong Ma Liang Shao Chaohua Xue Fuquan Deng Zhouyang Duan 《Polymer Bulletin》2014,71(9):2219-2234
Ethylene vinyl acetate copolymer/thermoplastic polyurethane (EVA/TPU) blending foams are rarely reported so far because of their poor compatibility, and addition of a compatibilizer to the blend system was our major interest, which can improve interfacial adhesion between the two phases. In this paper, TPU-grafted EVA (EVA-g-TPU), as a compatibilizer, was simply prepared using maleic anhydride-grafted EVA (EVA-g-MAH) and 4,4′ diamino diphenyl methane in the mixing process of TPU and EVA matrix. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to investigate the structures of EVA-g-TPU and the interfacial reaction in the mixing process, and the effect of EVA-g-TPU on compatibilization between the two phases of EVA/TPU blends was investigated using scanning electron microscopy. Finally, EVA/EVA-g-TPU/TPU foams based on the good compatibility of the resin blends were prepared, and the physical properties directly related to the compatibility were investigated as a function of the theoretical quantity (molar mass) of EVA-g-TPU (n EVA-g-TPU) in the foams. Moreover, the tensile strength, elongation at break, tear strength and compression set were improved by 19.0, 9.3, 43.6 and 7.5 %, respectively. Overall, EVA/EVA-g-TPU/TPU foams with excellent mechanical properties were obtained without sacrificing other important physical properties (lower density etc.) through popular and friendly means in this research. 相似文献
995.
Wu Li Dandan Wu Shulin Sun Guangfeng Wu Huixuan Zhang Yunjiao Deng Huiliang Zhang Lisong Dong 《Polymer Bulletin》2014,71(11):2881-2902
Glycidyl methacrylate-functionalized methyl methacrylate–butyl acrylate (GACR) core–shell structure copolymers were synthesized to toughen polylactide (PLA). With an increase in GACR content, the PLA/GACR blends showed decreased tensile strength and modulus; however, the elongation at break and the impact strength were significantly increased compared with that of PLA. The brittle fracture of neat PLA was gradually transformed into ductile fracture by the addiction of GACR. From dynamic mechanical analysis, the rigidity of the PLA/GACR blends was decreased with the increase of GACR content. The addition of GACR decreased the degree of crystallinity of PLA. The GACR was found to aggregate to form clusters with size increasing with increasing GACR content by transmission electron microscope analysis. The clusters dispersed in PLA matrix uniformly. It was found that PLA demonstrated large area, plastic deformation (shear yielding) and cavities in the blend upon being subjected the tensile and impact tests, which was an important energy-dissipation process and led to a toughened and transparent blend. 相似文献
996.
997.
998.
999.
1000.