全文获取类型
收费全文 | 5028篇 |
免费 | 370篇 |
国内免费 | 170篇 |
专业分类
电工技术 | 55篇 |
综合类 | 172篇 |
化学工业 | 2681篇 |
金属工艺 | 568篇 |
机械仪表 | 265篇 |
建筑科学 | 116篇 |
矿业工程 | 27篇 |
能源动力 | 23篇 |
轻工业 | 312篇 |
水利工程 | 8篇 |
石油天然气 | 44篇 |
武器工业 | 20篇 |
无线电 | 285篇 |
一般工业技术 | 827篇 |
冶金工业 | 88篇 |
原子能技术 | 24篇 |
自动化技术 | 53篇 |
出版年
2024年 | 19篇 |
2023年 | 99篇 |
2022年 | 169篇 |
2021年 | 222篇 |
2020年 | 156篇 |
2019年 | 159篇 |
2018年 | 123篇 |
2017年 | 151篇 |
2016年 | 155篇 |
2015年 | 168篇 |
2014年 | 210篇 |
2013年 | 784篇 |
2012年 | 234篇 |
2011年 | 304篇 |
2010年 | 179篇 |
2009年 | 198篇 |
2008年 | 198篇 |
2007年 | 243篇 |
2006年 | 223篇 |
2005年 | 194篇 |
2004年 | 186篇 |
2003年 | 133篇 |
2002年 | 104篇 |
2001年 | 106篇 |
2000年 | 108篇 |
1999年 | 84篇 |
1998年 | 107篇 |
1997年 | 87篇 |
1996年 | 59篇 |
1995年 | 86篇 |
1994年 | 58篇 |
1993年 | 40篇 |
1992年 | 53篇 |
1991年 | 31篇 |
1990年 | 21篇 |
1989年 | 22篇 |
1988年 | 19篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1976年 | 4篇 |
1974年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有5568条查询结果,搜索用时 15 毫秒
51.
52.
Walter Brockmann 《The Journal of Adhesion》1989,29(1):53-61
Adequate adhesion between metals and polymers is primarily the result of chemical bonds in the boundary layer. This region, however, is subject to degradation by moisture. Three modes of deterioration are observed. The first is a largely reversible weakening effect in the polymer layer near the metal oxide surface. The structure of this layer differs from that of the bulk and is influenced by the chemical and physical properties of the surface. The second is a slow transformation of the oxide by hydration and a diffusion of oxide constituents into the polymer. This process is irreversible and is influenced by the state of the surface and chemical properties of the polymer. The third is a fast deterioration of the oxide by primary corrosion usually initiating at an unprotected edge but occasionally arising within the body of a joint. 相似文献
53.
综述了聚合物共混增韧机理包括弹性体增韧、刚性粒子增韧、弹性体与刚性粒子协同增韧等研究进展;着重介绍了临界基体层厚度、损伤竞争准数、分子链参数、临界界面黏结条件、临界特征长度等几种源于单一粒子填充的脆韧转变判据,并分析其在复合粒子填充改性聚合物中的适用性。此外,还结合增韧机理和脆韧转变判据讨论了基体性能、分散相状态及相间界面黏结强度等因素对复合体系韧性的影响,提出寻找合适的复合分散相、适当调整复合粒子的结构比例、改善相间界面黏结以及设计最佳断裂路径仍将是今后努力的方向。 相似文献
54.
The adhesion energy between silicone rubber and glass has been obtained from the Johnson, Kendall and Roberts' test. The specific effect of ammonia on the quasi-equilibrium value has been studied as a function of the degree of crosslinking of the elastomer. For PDMS networks with lower molecular weight between crosslinks, the effect is more pronounced but completely reversible. This has been related to the increase in the non-dispersive part of the surface energy of the silicone due to the imbibed ammonia. In incompletely crosslinked hydroxyl-terminated PDMS, ammonia has a catalytic effect and is responsible for chemical bonding between the unreacted hydroxyl groups of the PDMS and the hydroxyl groups on glass. 相似文献
55.
In addition to molecular interaction and physical entanglement of the molecular chains across the interface in poly (vinyl chloride)-nitrile rubber joints, at high temperatures and long contact times interfacial chemical bonds may be formed which seem to couple the two adherends thereby resulting in cohesive failure of the rubber matrix on peeling. This is verified by performing the peel tests at high temperatures, low peel rates and under swollen conditions. Infrared spectroscopic studies of the PVC/NBR blend reveal the formation of chemical bonds at the contact temperatures studied. The peel fracture energy is found to depend on the acrylonitrile content and presence of carboxylic content in the NBR, and the presence of stabilizer and plasticizer in the PVC phase, in addition to the molding and testing conditions. 相似文献
56.
57.
Treated glass fibers (RICS, 3 and 6 mm in length) were added at a concentrations of 10, 20, and 30 phr in natural rubber (NR), nitrile rubber (NBR), and ethylene–propylene–diene comonomer (EPDM) formulations, in both plain and carbon black mixes. The compounds were mixed in two‐roll mill and were evaluated for their resistance to hot‐air aging, abrasion, compression set, Goodrich heat buildup, De Mattia fatigue, and for NR mixes, adhesion in the tensile mode. The vulcanizates of the three rubbers showed resistance to hot‐air aging. Abrasion resistance was poor for NR, and it improved with carbon black addition in the presence of treated glass fiber in NBR. In carbon‐black‐added EPDM vulcanizates, the abrasion resistance and fatigue resistance were better. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1124–1135, 2004 相似文献
59.
Yinzhong Guo Vijay M. Mannari Pulin Patel John L. Massingill 《Journal of Coatings Technology and Research》2006,3(4):327-331
A series of soybean oil phosphate ester polyols (SOPEP) was prepared by reaction of fully epoxidized soybean oil with phosphoric
acid and simultanoeous hydrolysis in the presence of a polar solvent. The polyols were characterized by determination of acid
value, oxirane number, hydroxyl value, molecular weight (GPC), and FTIR spectra. These polyols with varying amounts of acid
phosphate groups could be self-emulsified to form aqueous dispersions after neutralization with organic base. These aqueous
dispersion showed varying degrees of stability and their appearance ranged from opaque dispersions to translucent to clear
solutions. Waterborne coating compositions were prepared using these aqueous dispersions as principal components and their
thermally cured film properties were studied. it was found that by careful selection and formulation, SOPEPs can be successfully
used for low-VOC waterborne coating formulations. SOPEPs with 3.5% phosphate ester content showed visibly superior corrosion
resistance properties. 相似文献
60.
Hongyi Zhou 《应用聚合物科学杂志》2004,92(6):3901-3909
Efforts to evaluate interlayer adhesion of coextruded films are often hampered by the inability to initiate delamination. On the other hand, interlayer delamination was often noticed at cut or trimmed edges of coextruded films. In this study, a test method was developed by first initiating delamination by uniaxial stretching and then measuring interlayer adhesion by peel test. Delamination was initiated by uniaxial stretching under controlled conditions for samples with double‐neck geometry. The double‐neck geometry was designed to create a specimen for the subsequent 180° peel test. Peel force was used to quantify interlayer adhesion of coextruded films based on polycarbonate and its copolymers. With this two‐step technique, coextruded films with peel force as high as 5300 N/m or 30 lb./in. were quantified. In addition, effects of copolymer composition and coextrusion processing condition on interlayer adhesion of these coextruded films were clearly demonstrated. A great deal of variation of interlayer adhesion across film surface was also revealed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3901–3909, 2004 相似文献