全文获取类型
收费全文 | 1171篇 |
免费 | 20篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 28篇 |
综合类 | 36篇 |
化学工业 | 164篇 |
金属工艺 | 50篇 |
机械仪表 | 57篇 |
建筑科学 | 8篇 |
矿业工程 | 4篇 |
能源动力 | 45篇 |
轻工业 | 645篇 |
水利工程 | 1篇 |
石油天然气 | 11篇 |
武器工业 | 5篇 |
无线电 | 25篇 |
一般工业技术 | 43篇 |
冶金工业 | 5篇 |
自动化技术 | 69篇 |
出版年
2023年 | 7篇 |
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 11篇 |
2019年 | 14篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 55篇 |
2014年 | 46篇 |
2013年 | 48篇 |
2012年 | 55篇 |
2011年 | 93篇 |
2010年 | 42篇 |
2009年 | 63篇 |
2008年 | 63篇 |
2007年 | 106篇 |
2006年 | 96篇 |
2005年 | 88篇 |
2004年 | 56篇 |
2003年 | 67篇 |
2002年 | 54篇 |
2001年 | 42篇 |
2000年 | 24篇 |
1999年 | 23篇 |
1998年 | 17篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1986年 | 1篇 |
排序方式: 共有1196条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
壳聚糖是一种生物聚合物。壳聚糖纺丝可制备具有可吸收性的医用手术缝线。本研究主要探讨壳聚糖的分子结构特征及化学性能,寻求壳糖纺丝的最佳工艺条件和成纤方法,为壳聚糖的深度开发应用提供基础、数据及方法。 相似文献
5.
Study on high-strength composite portland cement with a larger amount of industrial wastes 总被引:1,自引:0,他引:1
It is one of important measures for the sustainable development of cement industry to utilize industrial wastes. High-strength composite portland cement with a large amount of granulated blast furnace slag (GBFS), fly ash and limestone was prepared by separate grinding method, optimizing gypsum and using activators. The total amounts of blending materials are between 45% and 65% and the strength grades of cements reach 525 or even 625 according to Chinese national standard for composite portland cement. Besides setting time and strength, the hydration heat, drying shrinkage and sulfate resistance were also determined. 相似文献
6.
The hydration phase and pore structure formation in the blends of sulfoaluminate-belite cement with Portland cement 总被引:1,自引:0,他引:1
Sulfoaluminate-belite (SAB) cements are an attractive class of low-energy cements from the viewpoint of saving energy and releasing less CO2 into the atmosphere during their production. Their hydraulic activity, however, does not match that of the ordinary Portland cement (PC) and needs improvement before they can be used on their own. However, SAB cements when blended with PC have the potential to be used effectively in traditional applications as shown by this study. Mortars made with blends of SAB cements and PC, and a cement-to-sand ratio of 1:3 by weight and a water-to-cement ratio of 0.5, indicate a superior protection against corrosion of steel to those made with blends of PC and blast-furnace slag (BFSPC). The prepared mortars were stored at 20 °C for 90 days under either a 60% relative humidity (RH)-dry air, or 100% RH-wet air conditions. With further improvement in the SAB cement quality through better understanding of their characteristics, a genuine competition between SAB/PC and BFSPC can be expected in practice. 相似文献
7.
Isothermal melt spinning experiments have been conducted using two polyethylene melts of low density (LDPE) and high density
(HDPE) to produce steady state spinline profiles. The data revealed the threadline extensional viscosity exhibiting a contrasting
picture : extension thickening behavior for LDPE and extension thinning one for HDPE. A White-Metzner model having a strain
rate-dependent relaxation time was then found to be able to simulate this dichotomy in melt spinning fairly well: the fluids
whose relaxation times have smaller strain rate-dependence can fit LDPE data with extension thickening extensional viscosity
whereas the fluids whose relaxation times have larger strain rate-dependence can fit HDPE data with extension thinning extensional
viscosity. This dichotomous nature of viscoelastic fluids is also believed to be able to explain other similar contrasting
phenomena exhibited by polymer melts, such as vortex/no vortex in entry flows, cohesive/ductile fracture modes in extension,
and more/less stable draw resonance than Newtonian fluids. 相似文献
8.
铝合金熔体旋转喷吹除气净化过程模拟 总被引:1,自引:0,他引:1
采用计算机模拟方法对铝合金熔体旋转喷吹除气净化过程的温度场以及流场进行分析。结果表明,在转杆内部放置一个导气管,可以显著降低气体温度,从而可以有效地解决旋转喷头由于熔剂因高温变软而堵塞的问题;旋转速度和进气流量对铝合金熔体旋转喷吹除气净化效果具有重要影响,应该根据具体情况选择合适的工艺参数。熔池为方形结构时,气体主要从对角处出去,而远离对角处的体积分数却显著降低,甚至可能发生吸气。 相似文献
9.
Number of blends were prepared by intergrinding clinker, gypsum, fly ash, calcined clay, microsilica and limestone in laboratory ball mill in varying percentages, and their physical properties such as fineness, consistency, setting time and compressive strength have been determined. The durability tests on selected compositions were also conducted by exposing the mortar cubes separately in 5% Na2SO4 and 5% NaCl solutions till the age of 90 and 180 days. The performance was observed by compressive strength development criteria after various length of exposure. Results have been discussed and found that the durability of blended cement is higher than the ordinary Portland cement. 相似文献
10.