全文获取类型
收费全文 | 20335篇 |
免费 | 944篇 |
国内免费 | 715篇 |
专业分类
电工技术 | 790篇 |
综合类 | 634篇 |
化学工业 | 3170篇 |
金属工艺 | 1921篇 |
机械仪表 | 1377篇 |
建筑科学 | 977篇 |
矿业工程 | 938篇 |
能源动力 | 1202篇 |
轻工业 | 1314篇 |
水利工程 | 126篇 |
石油天然气 | 1001篇 |
武器工业 | 112篇 |
无线电 | 2543篇 |
一般工业技术 | 2377篇 |
冶金工业 | 808篇 |
原子能技术 | 563篇 |
自动化技术 | 2141篇 |
出版年
2024年 | 43篇 |
2023年 | 248篇 |
2022年 | 401篇 |
2021年 | 589篇 |
2020年 | 542篇 |
2019年 | 508篇 |
2018年 | 549篇 |
2017年 | 616篇 |
2016年 | 626篇 |
2015年 | 678篇 |
2014年 | 1127篇 |
2013年 | 1235篇 |
2012年 | 1093篇 |
2011年 | 1589篇 |
2010年 | 1061篇 |
2009年 | 1100篇 |
2008年 | 1019篇 |
2007年 | 1078篇 |
2006年 | 1075篇 |
2005年 | 970篇 |
2004年 | 822篇 |
2003年 | 689篇 |
2002年 | 634篇 |
2001年 | 541篇 |
2000年 | 492篇 |
1999年 | 531篇 |
1998年 | 405篇 |
1997年 | 386篇 |
1996年 | 295篇 |
1995年 | 267篇 |
1994年 | 188篇 |
1993年 | 118篇 |
1992年 | 113篇 |
1991年 | 79篇 |
1990年 | 53篇 |
1989年 | 67篇 |
1988年 | 49篇 |
1987年 | 24篇 |
1986年 | 28篇 |
1985年 | 9篇 |
1984年 | 14篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1973年 | 4篇 |
1960年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
73.
Yuuzou Kawahara 《Corrosion Science》2002,44(2):223-245
Corrosion products on two typical materials, SA213-T12 steel and alloy 625 exposed to the actual combustion gas, were analyzed in addition to laboratory tests for penetration of corrosive matter. It has been clarified that corrosion products of oxides containing a little chlorides and sulphides show lamellar structures and that at the alloy-scale interface, chlorination, sulphidation, and oxidation occur under a low PO2-high PCl2 condition. The formation of scale structures and the effect of corrosion-resistant alloying elements can be explained according to the stability tendencies of metals, chlorides, and oxides in the M-Cl-O equilibrium diagrams. The severity of corrosion environments at the interface is influenced by the penetration extent of corrosive matters through deposits and scales, and the protective effects of oxide films derived from alloying elements play an important role in preventing the corrosion. On the other hand, it has been shown that thermal fluctuation characterized in this kind of environment makes the lamellar scale structures and sometimes breaks and peels off the scale, and thus accelerates the corrosion. On the basis of the above mentioned knowledge, a new corrosion model is presented. 相似文献
74.
75.
Effects of electrical discharge surface modification of superalloy Haynes 230 with aluminum and molybdenum on oxidation behavior 总被引:1,自引:0,他引:1
Ching-Yuan Bai 《Corrosion Science》2007,49(10):3889-3904
The effects of the electrical discharge alloying (EDA) process on improving the high temperature oxidation resistance of the Ni-based superalloy Haynes 230 have been investigated. The 85 at.% Al and 15 at.% Mo composite electrode provided the surface alloying materials. An Al-rich layer is produced on the surface of the EDA specimen alloyed with positive electrode polarity, whereas, many discontinuous piled layers are attached to the surface of the EDA superalloy when negative electrode polarity is selected. The oxidation resistance of the specimen alloyed with positive electrode polarity is better than that of the unalloyed superalloy, and the effective temperature of oxidation resistance of the alloyed layer can be achieved to 1100 °C. Conversely, the oxidation resistance of the other EDA specimen alloyed with negative electrode polarity is even worse than that of the unalloyed superalloy. 相似文献
76.
77.
78.
姜无疾 《电子制作.电脑维护与应用》2015,(8)
研制了气动高空擦玻璃机器人,该机器人包括产生真空吸附功能的气动真空模块,用于实现类似于四足动物爬行的爬行模块,用于擦拭玻璃的擦拭模块,以及对以上所述模块进行控制的控制模块。它能实现在高层建筑物的玻璃外墙进行攀爬,同时对墙体进行彻底擦洗。 相似文献
79.
Fuzzy utility mining has been an emerging research issue because of its simplicity and comprehensibility. Different from traditional fuzzy data mining, fuzzy utility mining considers not only quantities of items in transactions but also their profits for deriving high fuzzy utility itemsets. In this paper, we introduce a new fuzzy utility measure with the fuzzy minimum operator to evaluate the fuzzy utilities of itemsets. Besides, an effective fuzzy utility upper-bound model based on the proposed measure is designed to provide the downward-closure property in fuzzy sets, thus reducing the search space of finding high fuzzy utility itemsets. A two-phase fuzzy utility mining algorithm, named TPFU, is also proposed and described for solving the problem of fuzzy utility mining. At last, the experimental results on both synthetic and real datasets show that the proposed algorithm has good performance. 相似文献
80.
姜磊 《数字社区&智能家居》2013,(10):6423-6425,6430
本设计是基于MCU的一款高效率键盘输入系统。通过对分立按键和普通二极管的合理布局,实现了一种利用N个双向I/O端口确定N2+N个键值的键盘电路设计。实验证明,该键盘电路结构简单、抗干扰能力强、稳定性好,具有很高的使用价值。 相似文献