全文获取类型
收费全文 | 48451篇 |
免费 | 5247篇 |
国内免费 | 2886篇 |
专业分类
电工技术 | 3968篇 |
综合类 | 3273篇 |
化学工业 | 12168篇 |
金属工艺 | 4105篇 |
机械仪表 | 2133篇 |
建筑科学 | 4810篇 |
矿业工程 | 732篇 |
能源动力 | 4236篇 |
轻工业 | 2330篇 |
水利工程 | 670篇 |
石油天然气 | 1748篇 |
武器工业 | 758篇 |
无线电 | 3687篇 |
一般工业技术 | 7310篇 |
冶金工业 | 2780篇 |
原子能技术 | 780篇 |
自动化技术 | 1096篇 |
出版年
2024年 | 280篇 |
2023年 | 949篇 |
2022年 | 1369篇 |
2021年 | 1751篇 |
2020年 | 1918篇 |
2019年 | 1742篇 |
2018年 | 1618篇 |
2017年 | 1943篇 |
2016年 | 1930篇 |
2015年 | 1932篇 |
2014年 | 2755篇 |
2013年 | 3292篇 |
2012年 | 3165篇 |
2011年 | 3412篇 |
2010年 | 2568篇 |
2009年 | 2714篇 |
2008年 | 2383篇 |
2007年 | 2993篇 |
2006年 | 2893篇 |
2005年 | 2194篇 |
2004年 | 1938篇 |
2003年 | 1585篇 |
2002年 | 1460篇 |
2001年 | 1203篇 |
2000年 | 1043篇 |
1999年 | 852篇 |
1998年 | 720篇 |
1997年 | 664篇 |
1996年 | 531篇 |
1995年 | 436篇 |
1994年 | 340篇 |
1993年 | 289篇 |
1992年 | 286篇 |
1991年 | 245篇 |
1990年 | 209篇 |
1989年 | 173篇 |
1988年 | 130篇 |
1987年 | 87篇 |
1986年 | 75篇 |
1985年 | 88篇 |
1984年 | 81篇 |
1983年 | 64篇 |
1982年 | 70篇 |
1981年 | 32篇 |
1980年 | 21篇 |
1979年 | 11篇 |
1965年 | 14篇 |
1959年 | 13篇 |
1957年 | 11篇 |
1955年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Inspired by biological systems in which damage triggers an autonomic healing response, a polymer composite material that can heal itself when cracked has been developed. In this work, compression and tensile properties of a self-healed fibre reinforced epoxy composites were investigated. Microencapsulated epoxy and mercaptan healing agents were incorporated into a glass fibre reinforced epoxy matrix to produce a polymer composite capable of self-healing. The self-repair microcapsules in the epoxy resin would break as a result of microcrack expansion in the matrix, and letting out the strong repair agent to recover the mechanical strength with a relative healing efficiency of up to 140% which is a ratio of healed property value to initial property value or healing efficiency up to 119% if using the healed strength with the damaged strength. 相似文献
3.
Thin Film Thermoelectric Metal–Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity 下载免费PDF全文
4.
Temperature history can have a significant effect on the strength of water-saturated chalk.In this study,hydrostatic stress cycles are applied to understand the mechanical response of chalk samples exposed to temperature cycling between each stress cycle,compared to the samples tested at a constant temperature.The total accumulated strain during a stress cycle and the irreversible strain are reported.Chalk samples from Kansas(USA)and Mons(Belgium),with different degrees of induration(i.e.amount of contact cementation),were used.The samples were saturated with equilibrated water(polar)and nonpolar Isopar H oil to quantify water weakening.All samples tested during 10 stress cycles with varying temperature(i.e.temperature cycled in between each stress cycle)accumulated more strain than those tested at constant temperatures.All the stress cycles were performed at 30℃.The two chalk types behaved similarly when saturated with Isopar H oil,but differently when saturated with water.When saturated with water,the stronger Kansas chalk accumulated more total strain and more irreversible strain within each stress cycle than the weaker Mons chalk. 相似文献
5.
Suitability,efficiency and microbiological safety of novel physical technologies for the processing of ready‐to‐eat meals,meats and pumpable products 下载免费PDF全文
Alexandros Ch. Stratakos Anastasios Koidis 《International Journal of Food Science & Technology》2015,50(6):1283-1302
Consumer studies and market reports show an increase in consumption of ready‐to‐eat (RTE) foods. Although conventional processing technologies can in most cases produce safe products, they can also lead to the degradation of nutritional compounds and negatively affect quality characteristics. Consumers strongly prefer food that is minimally processed with the maximum amount of health‐promoting substances. Novel processing technologies as pre‐ or post‐treatment decontamination methods or as substitutes of conventional technologies have the potential to produce foods that are safe, rich in nutrient content and with superior organoleptic properties. Combining novel with conventional processes can eliminate potential drawbacks of novel technologies. This review examines available scientific information and critically evaluates the suitability and efficiency of various novel thermal and nonthermal technologies in terms of microbial safety, quality as well as nutrient content on the production of RTE meals, meats and pumpable products. 相似文献
6.
7.
8.
Field Static Load Test on Kao-Ping-Hsi Cable-Stayed Bridge 总被引:1,自引:0,他引:1
Field load testing is an effective method for understanding the behavior and fundamental characteristics of a cable-stayed bridge. This paper presents the results of field static load tests on the Kao-Ping-Hsi cable-stayed bridge, the longest cable-stayed bridge in Taiwan, before it was open to traffic. A total of 40 loading cases, including the unit and distributed bending and torsion loading effects, were conducted to investigate the bridge behavior. The atmospheric temperature effect on the variations of the main girder deflections was also monitored. The results of static load testing include the main girder deflections, the flexural strains of the prestressed concrete girder, and the variations of the cable forces. A three-dimensional finite-element model was developed. The results show that the bridge under the planned load test conditions has linear superposition characteristics and the analytical model shows a very good agreement with the bridge responses. Further discussion of deflection and cable forces of the design specifications for a cable-stayed bridge is also presented. 相似文献
9.
从稳态到动态的空气调节 总被引:1,自引:0,他引:1
分析传统空调所提供的稳态参数微气候环境不一定能达到人的舒适和健康的要求,提出符合人本身生理习惯的空调送风方式应该是动态空气调节.认为个人可调节和适宜的环境渐变能同时保证舒适和健康两方面需要. 相似文献
10.
Polyaryloxydiphenylsilanes were prepared from phosphorus‐containing diols and diphenydichlorolsilane through solution polymerization. With a stoichiometric imbalance in feed monomers, the resulting polymers exhibited moderate melting points and good processing properties. The polymers prepared showed initial decomposition temperatures above 340 °C, excellent thermal stability, high char yields at 850 °C and very high limited oxygen index values of 56–59. The polymers' char yields and their (P + Si) contents showed linear relationships. © 2003 Society of Chemical Industry 相似文献