全文获取类型
收费全文 | 5551篇 |
免费 | 444篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 65篇 |
综合类 | 3篇 |
化学工业 | 1395篇 |
金属工艺 | 65篇 |
机械仪表 | 159篇 |
建筑科学 | 233篇 |
矿业工程 | 9篇 |
能源动力 | 254篇 |
轻工业 | 944篇 |
水利工程 | 67篇 |
石油天然气 | 26篇 |
无线电 | 387篇 |
一般工业技术 | 894篇 |
冶金工业 | 331篇 |
原子能技术 | 31篇 |
自动化技术 | 1141篇 |
出版年
2024年 | 7篇 |
2023年 | 44篇 |
2022年 | 51篇 |
2021年 | 217篇 |
2020年 | 171篇 |
2019年 | 200篇 |
2018年 | 242篇 |
2017年 | 211篇 |
2016年 | 272篇 |
2015年 | 199篇 |
2014年 | 294篇 |
2013年 | 492篇 |
2012年 | 401篇 |
2011年 | 468篇 |
2010年 | 319篇 |
2009年 | 334篇 |
2008年 | 314篇 |
2007年 | 283篇 |
2006年 | 226篇 |
2005年 | 172篇 |
2004年 | 171篇 |
2003年 | 120篇 |
2002年 | 123篇 |
2001年 | 54篇 |
2000年 | 43篇 |
1999年 | 41篇 |
1998年 | 92篇 |
1997年 | 58篇 |
1996年 | 43篇 |
1995年 | 41篇 |
1994年 | 44篇 |
1993年 | 37篇 |
1992年 | 24篇 |
1991年 | 25篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 16篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 20篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 11篇 |
1975年 | 5篇 |
1974年 | 4篇 |
排序方式: 共有6004条查询结果,搜索用时 15 毫秒
1.
2.
The incorporation of viscoelastic materials represents an effective strategy to reduce the vibratory level of structural components. Thermoplastic vulcanizates (TPVs) are a special type of viscoelastic material that combines the elastomeric properties of rubbers with the easy processing of thermoplastics. In the present work, we propose innovative ways to improve the damping properties of high‐performance TPVs by using rubbers with carboxylic functionalities. For that, TPVs from physical blends of carboxylated hydrogenated acrylonitrile butadiene rubber (XHNBR) and polyamide 6 (PA6) were prepared. The chain dynamics of different mixed crosslink systems containing peroxide, metal oxides and hindered phenolic antioxidants were investigated in order to find the most suitable strategy to design a high‐performance TPV system with upgraded damping properties. The results indicate that the damping performance of the TPV system can be tailored by controlling the type and magnitude of the bonding interactions between the mixed crosslink system and the XHNBR rubber phase. Therefore, this study demonstrates the potential of TPV systems containing carboxylic rubbers as high‐performance damping materials. © 2020 Society of Chemical Industry 相似文献
3.
4.
Fruit flesh volatile and carotenoid profile analysis within the Cucumis melo L. species reveals unexploited variability for future genetic breeding 下载免费PDF全文
5.
6.
Physicochemical Quality,Fatty Acid Composition,and Sensory Analysis of Nellore Steers Meat Fed with Inclusion of Condensed Tannin in the Diet 下载免费PDF全文
7.
Mahesa Akbar Jose Luis Curiel-Sosa 《International Journal of Mechanics and Materials in Design》2018,14(4):647-667
In this paper, a novel hybrid mathematical/isogeometric analysis (IGA) scheme is implemented to evaluate the energy harvesting of the piezoelectric composite plate under dynamic bending. The NURBS-based IGA is applied to obtain the structural response exerted by the mechanical loading. The dynamic responses conveniently coupled with the governing voltage differential equations to estimate the energy harvested. The capabilities of the scheme are shown with the comparison against analytical and full electromechanical finite element results. As there is no need of fully coupled electromechanical element, the scheme provides cheaper computational cost and could be implemented with standard computational software. Thus, it gives great benefit for early design stage. Moreover, the robustness of the scheme is shown by the couple with high order IGA element which has been proven less prone to the shear locking phenomena in the literature. The computational results show greater accuracy on structural responses and energy estimation for a very thin plate compared to the couple with standard finite element method. 相似文献
8.
9.
Yadira D. Cerda‐Sumbarda Ivan Zapata‐Gonzalez Angel Licea‐Claverie Arturo Zizumbo‐Lopez Luis F. Ramos‐de Valle Adriana Espinoza‐Martínez 《Polymer Engineering and Science》2019,59(1):170-181
The preparation of poly(hexylacrylate)core‐poly(ethyleneglycol methacrylate)shell (PHA‐co‐PEGMA) nanogels, to be used as fillers in nanocomposite hydrogels, is reported. Stable nanogels with particle sizes between 90–300 nm were obtained varying the conditions of synthesis. The synthesis recipe of the nanogels could be easily scaled up. Purified and dispersed nanogels in aqueous solution were used as soft fillers for poly(2‐hydroxyethyl methacrylate) (PHEMA) hydrogels, crosslinked with ethylene glycol dimethacrylate (EGDMA). The obtained nanocomposite hydrogels exhibit a larger swelling capacity and a higher thermal stability in comparison with the non‐filled PHEMA hydrogels. Young, storage, and lost moduli, increase largely, in the better case up to 72.5% in the swollen state; while in the dry state the storage modulus increase up to 4.7 fold with a very low load on nanogels (0.64 wt%); resulting in biomaterials with improved properties with potential applications in medical devices. POLYM. ENG. SCI., 59:170–181, 2019. © 2018 Society of Plastics Engineers 相似文献
10.
A numerical study of the combustion of lean methane/air mixtures in a porous media burner is performed using novelty geometry, cylindrical annular space. The combustion process takes place in the porous space located between two pipes, which are filled with alumina beads of 5.6 mm diameter forming a porosity of 0.4. The outer tube diameter of 3.82 cm is isolated; meanwhile the inner tube of 2 cm in diameter is covered by a continuous set of thermoelectric elements (TE) for transforming heat energy into electricity. To achieve and maintain the proper temperature gradient on TE, convective heat losses are considered from the TE. Computer simulations focus on the two-dimensional (2D) temperature analysis and displacement dynamics of the combustion front inside the reactor, depending on the values of the filtration velocity (0.1 to 1.0 m/s), the heat loss coefficient from the internal cylinder (400–1500 W/m2/K), and the fuel equivalence ratio (0.06– 0.5). The conditions that maximized the overall performance of the process of energy conversion are: 0.7 m/s of the filtration velocity, 0.363 of the fuel equivalence ratio and 1500 W/(m2·K) of the heat transfer coefficient from the internal cylinder, to obtain 2.05 V electrical potential, 21 W of electrical power, and 5.64% of the overall process efficiency. The study shows that the cylindrical annular geometry can be used for converting the energy of combustion from lean gas mixtures into electricity, with a performance similar to the specified by manufacturers of thermoelectric elements (TE). 相似文献