全文获取类型
收费全文 | 675篇 |
免费 | 84篇 |
国内免费 | 37篇 |
专业分类
电工技术 | 39篇 |
综合类 | 37篇 |
化学工业 | 83篇 |
金属工艺 | 37篇 |
机械仪表 | 47篇 |
建筑科学 | 42篇 |
矿业工程 | 37篇 |
能源动力 | 34篇 |
轻工业 | 87篇 |
水利工程 | 39篇 |
石油天然气 | 48篇 |
武器工业 | 12篇 |
无线电 | 90篇 |
一般工业技术 | 52篇 |
冶金工业 | 43篇 |
原子能技术 | 12篇 |
自动化技术 | 57篇 |
出版年
2024年 | 10篇 |
2023年 | 26篇 |
2022年 | 33篇 |
2021年 | 35篇 |
2020年 | 19篇 |
2019年 | 35篇 |
2018年 | 23篇 |
2017年 | 12篇 |
2016年 | 26篇 |
2015年 | 33篇 |
2014年 | 23篇 |
2013年 | 32篇 |
2012年 | 37篇 |
2011年 | 33篇 |
2010年 | 40篇 |
2009年 | 35篇 |
2008年 | 32篇 |
2007年 | 27篇 |
2006年 | 54篇 |
2005年 | 24篇 |
2004年 | 36篇 |
2003年 | 25篇 |
2002年 | 16篇 |
2001年 | 22篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 20篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有796条查询结果,搜索用时 9 毫秒
81.
Chenglong Zhang Jingming Fei Lei Guo Jianxing Yu Binbin Zhang Zheng Yan Fuxing Ye 《Ceramics International》2018,44(8):8818-8826
LaPO4 powders were produced by a chemical co-precipitation and calcination method. The ceramic exhibited a monazite structure, kept phase stability at 1400?°C for 100?h, and had low thermal conductivity (~ 1.41?W/m?K, 1000?°C). LaPO4/Y2O3 partially stabilized ZrO2 (LaPO4/YSZ) double-ceramic-layer (DCL) thermal barrier coatings (TBCs) were fabricated by air plasma spray. The LaPO4 coating contained many nanozones. Thermal cycling tests indicated that the spallation of LaPO4/YSZ DCL TBCs initially occurred in the LaPO4 coating. The failure mode was similar to those of many newly developed TBCs, probably due to the low toughness of the ceramics. LaPO4/YSZ DCL TBCs were highly resistant to V2O5 corrosion. Exposed to V2O5 at 700–900?°C for 4?h, La(P,V)O4 formed as the corrosion product, which had little detrimental effect on the coating microstructure. At 1000?°C for 4?h, a minor amount of LaVO4 was generated. 相似文献
82.
Effect of Industrial Chemical Refining on the Physicochemical Properties and the Bioactive Minor Components of Peanut Oil 下载免费PDF全文
Minghui Zhu Xin Wen Jinhong Zhao Fang Liu Yuanying Ni Liyan Ma Jingming Li 《Journal of the American Oil Chemists' Society》2016,93(2):285-294
The effect of the industrial chemical refining process on the physicochemical properties, fatty acid composition, and bioactive minor components of peanut oil was studied. The results showed that the moisture and volatile matter content, acid value, peroxide value, and p‐anisidine value were significantly changed (P < 0.05) after the complete refining process. No significant variation (P > 0.05) in the iodine value was observed among all the peanut oil samples. Similar changes were observed in the DPPH radical scavenging activity and the total tocol content during chemical refining. In addition, chemical refining did not have much effect on the fatty acid composition, except for certain changes of several individual fatty acids. Moreover, the chemical refining resulted in 23.6, 23.1, and 9.5 % losses of squalene, total phytosterols, and total tocols (α, β, γ, δ‐tocopherols and α, β, γ, δ‐tocotrienols), respectively. The degumming–neutralization step caused the greatest overall reduction of these bioactive minor components. However, the concentrations of α‐tocotrienol and γ‐tocotrienol increased after full refining. Furthermore, chemical refining slightly changed the relative proportions of individual phytosterols and individual tocols. 相似文献
83.
围绕施工阶段对通风和空调工程的监理工作,以国家相关规范为指导,结合工作实践,从理论和实务上对如何有效地做好本分部工程监理工作进行有效的探讨。 相似文献
84.
85.
基于CAN总线时钟同步机制的研究 总被引:1,自引:0,他引:1
随着分布式控制网络的发展,对控制的精度和准确度的要求越来越高。分布式控制网络系统中的核心问题之一就是时钟同步问题。近年来,CAN总线作为控制系统的一种通讯网络在分布式网络控制系统中发展较快。因此文章主要研究CAN网络中的时钟同步问题的解决方法。 相似文献
86.
87.
88.
China has abundant natural gas resources with low exploration level. The discovery rate of resources is 10% on the average, boasting a great potential. By the end of 2006, the ascertained geological gas reserves in China has amounted to 5.4×10^12m^3, among which 9 gas fields has 1000~108m3 of ascertained geological reserves or more. The "large gas fields" are referred to those gas fields with recoverable reserves exceeding 85 billion cubic meters. Since the Sixth Five-Year Plan, China's gas industry has developed rapidly and gas reserve and output has witnessed a substantial increase, in which the discovery of large gas fields has played a very important role. With the progress of technology, more gas resources will be discovered with gas reserves growing rapidly in China. The second leap of China's oil and gas industry mainly focuses on the gas industry while the leap of gas industry mainly relies on the discovery of large gas fields. 相似文献
89.
1980年彭希龄在准噶尔盆地克拉美丽地区石钱滩东侧命名了一组地层为“金沟组(C_3j)”。1982年笔者在“金沟组”的钙质泥岩薄夹层中采得了古鳕鱼类(Palaeoniscidae)化石,同时在鱼化石层中还采得近卵形小微体蚌[Microdontellasubovata(Jones)],故认为“金沟组”的时代应为晚二叠世。根据“金沟组”中孢粉分析成果,证实“金沟组”与平地泉组(P_2p)为同时异相沉积,故“金沟组”应予废弃,正名为平地泉组。 相似文献
90.
This study is concerned with developing a two-dimensional two-phase model thatsimulate the movement of non-aqueous phase liquid (NAPL) in a fracture-rock matrix system. Theintrinsic permeability and the fracture aperture are represented in the model via its Karhunen-Loeve expansion. Other parameters and the nodal unknowns, water saturations and waterpressures, are represented by their stochastic spectral expanions. The errors resulting fromtruncation of Karhunen - Loeve and polynomial chaos expansions to a finite number of terms areanalyzed. The eigenvalues of stochastic process is found out for any point in the special domain ofthe problem at any instant in time. 相似文献