全文获取类型
收费全文 | 69404篇 |
免费 | 7444篇 |
国内免费 | 4193篇 |
专业分类
电工技术 | 4390篇 |
技术理论 | 2篇 |
综合类 | 5264篇 |
化学工业 | 10882篇 |
金属工艺 | 4154篇 |
机械仪表 | 4617篇 |
建筑科学 | 5014篇 |
矿业工程 | 1936篇 |
能源动力 | 1690篇 |
轻工业 | 6853篇 |
水利工程 | 1582篇 |
石油天然气 | 3159篇 |
武器工业 | 677篇 |
无线电 | 8079篇 |
一般工业技术 | 7998篇 |
冶金工业 | 3012篇 |
原子能技术 | 923篇 |
自动化技术 | 10809篇 |
出版年
2024年 | 413篇 |
2023年 | 1222篇 |
2022年 | 2318篇 |
2021年 | 3016篇 |
2020年 | 2355篇 |
2019年 | 2025篇 |
2018年 | 2228篇 |
2017年 | 2454篇 |
2016年 | 2303篇 |
2015年 | 3239篇 |
2014年 | 4010篇 |
2013年 | 4760篇 |
2012年 | 5311篇 |
2011年 | 5603篇 |
2010年 | 5093篇 |
2009年 | 4881篇 |
2008年 | 4654篇 |
2007年 | 4409篇 |
2006年 | 4080篇 |
2005年 | 3344篇 |
2004年 | 2356篇 |
2003年 | 1867篇 |
2002年 | 1789篇 |
2001年 | 1510篇 |
2000年 | 1180篇 |
1999年 | 942篇 |
1998年 | 630篇 |
1997年 | 516篇 |
1996年 | 465篇 |
1995年 | 361篇 |
1994年 | 303篇 |
1993年 | 240篇 |
1992年 | 201篇 |
1991年 | 157篇 |
1990年 | 115篇 |
1989年 | 90篇 |
1988年 | 80篇 |
1987年 | 59篇 |
1986年 | 60篇 |
1985年 | 32篇 |
1984年 | 27篇 |
1983年 | 23篇 |
1982年 | 30篇 |
1981年 | 19篇 |
1980年 | 17篇 |
1979年 | 21篇 |
1978年 | 16篇 |
1977年 | 20篇 |
1976年 | 36篇 |
1975年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
83.
The electromagnetic properties of electrically thick rectangular microstrip antennas were investigated experimentally. Antennas were fabricated with different patch sizes and with electrical thicknesses ranging from 0.03 to 0.23 wavelengths in the dielectric substrate. The resonant frequencies were measured and compared to existing formulas. The bandwidth was calculated as a function of electrical thickness and the antenna radiation patterns were measured. 相似文献
84.
《建设工程工程量清单计价规范》的颁布实施,是工程建设领域的一件大事,为了更好的推行和施行计价规范,应做好多方面的工作。 相似文献
85.
Degradation Behaviors of Metal-Induced Laterally Crystallized n-Type Polycrystalline Silicon Thin-Film Transistors Under DC Bias Stresses 总被引:1,自引:0,他引:1
Min Xue Mingxiang Wang Zhen Zhu Dongli Zhang Man Wong 《Electron Devices, IEEE Transactions on》2007,54(2):225-232
Device degradation behaviors of typical-sized n-type metal-induced laterally crystallized polycrystalline silicon thin-film transistors were investigated in detail under two kinds of dc bias stresses: hot-carrier (HC) stress and self-heating (SH) stress. Under HC stress, device degradation is the consequence of HC induced defect generation locally at the drain side. Under a unified model that postulates, the establishment of a potential barrier at the drain side due to carrier transport near trap states, device degradation behavior such as asymmetric on current recovery and threshold voltage degradation can be understood. Under SH stress, a general degradation in subthreshold characteristic was observed. Device degradation is the consequence of deep state generation along the entire channel. Device degradation behaviors were compared in low Vd-stress and in high Vd-stress condition. Defect generation distribution along the channel appears to be different in two cases. In both cases of SH degradation, asymmetric on current recovery was observed. This observation, when in low Vd-stress condition, is tentatively explained by dehydrogenation (hydrogenation) effect at the drain (source) side during stress 相似文献
86.
王龙 《数字社区&智能家居》2006,(7):5-5,19
本文介绍了MOC组件的安装与使用,并给出了C#.NET for Windows数据库项目开发中应用MOC组件编程的一个实例。 相似文献
87.
全球化的挑战——再论面对WTO的中国暖通空调业 总被引:6,自引:2,他引:4
2001年11月,中国在历时15年之后终于加入了世贸组织。针对中国暖通空调业从体制、观念和人才培养上如何适应经济全球化的形势,首次提出个人观点,并对暖通空调业如何发挥自身优势、参与国际竞争提出了建议。 相似文献
88.
通过都昌县2000年旱情及受灾情况的分析,揭示了产生这种现象的原因,并且提出了相应解决问题的对策。 相似文献
89.
This paper presents a method for multi-area power system total transfer capability (TTC) computation. This computation takes into account the limits on the line flows, bus voltage magnitude, generator reactive power, voltage stability, as well as the loss of line contingencies. The multi-area TTC problem is solved by using a network decomposition approach based on REI-type network equivalents. Each area uses REI equivalents of external areas to compute its TTC via the continuation power flow (CPF). The choice and updating procedure for the continuation parameter employed by the CPF is implemented in a distributed but coordinated manner. The proposed method leads to potential gains in the computational efficiency with limited data exchanges between areas. The developed procedure is successfully applied to the three-area IEEE 118-bus test system. Numerical comparisons between the integrated and the proposed multi-area solutions are presented for validation. 相似文献
90.