全文获取类型
收费全文 | 26571篇 |
免费 | 2336篇 |
国内免费 | 1595篇 |
专业分类
电工技术 | 1756篇 |
技术理论 | 2篇 |
综合类 | 2133篇 |
化学工业 | 4078篇 |
金属工艺 | 1447篇 |
机械仪表 | 1664篇 |
建筑科学 | 2153篇 |
矿业工程 | 681篇 |
能源动力 | 724篇 |
轻工业 | 2566篇 |
水利工程 | 560篇 |
石油天然气 | 1251篇 |
武器工业 | 295篇 |
无线电 | 3175篇 |
一般工业技术 | 2823篇 |
冶金工业 | 1199篇 |
原子能技术 | 351篇 |
自动化技术 | 3644篇 |
出版年
2024年 | 108篇 |
2023年 | 448篇 |
2022年 | 764篇 |
2021年 | 1024篇 |
2020年 | 828篇 |
2019年 | 668篇 |
2018年 | 700篇 |
2017年 | 879篇 |
2016年 | 735篇 |
2015年 | 1085篇 |
2014年 | 1464篇 |
2013年 | 1682篇 |
2012年 | 1877篇 |
2011年 | 1957篇 |
2010年 | 1868篇 |
2009年 | 1735篇 |
2008年 | 1755篇 |
2007年 | 1677篇 |
2006年 | 1559篇 |
2005年 | 1291篇 |
2004年 | 994篇 |
2003年 | 888篇 |
2002年 | 922篇 |
2001年 | 797篇 |
2000年 | 589篇 |
1999年 | 483篇 |
1998年 | 371篇 |
1997年 | 288篇 |
1996年 | 240篇 |
1995年 | 197篇 |
1994年 | 168篇 |
1993年 | 101篇 |
1992年 | 98篇 |
1991年 | 59篇 |
1990年 | 58篇 |
1989年 | 47篇 |
1988年 | 24篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 4篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1971年 | 2篇 |
1959年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
1.
2.
3.
介绍机械制造厂燃煤锅炉的烟尘特点,分析滤料失效的原因,提出一套针对该工况的滤料解决方案。介绍针对复杂工况条件所选用的纤维种类以及复合面层原料成分配比的确定,最终选用针刺工艺加工并对该新产品的基本性能进行了测试分析。 相似文献
4.
宁东供水工程供水水泵共有卧式和立式离心泵2种方案可供选择,也是工程论证时争论的焦点,经综合比较及主机设备的国际招标,最终确定了奥地利安德里兹公司的卧式双吸中开式离心泵为宁东供水工程的供水水泵。 相似文献
5.
6.
BOOMBOX是美国Seismic Source 公司生产的新型放炮系统.文章阐述了该放炮系统的参数设置、与408UL的连接、与有线放炮系统的连接以及具体操作过程. 相似文献
7.
Disciplinary and linguistic considerations for academic Web linking: An exploratory hyperlink mediated study with Mainland China and Taiwan 总被引:4,自引:0,他引:4
The Web has become an important means of academic information exchange and can be used to give new insights into patterns
of informal scholarly communication. This study develops new methods to examine patterns of university Web linking, focusing
on Mainland China and Taiwan, and including language considerations. Multiple exploratory investigations into Web links were
conducted between universities in these two places. Firstly, inlinks were counted to each university Web site from its national
peers using four alternative Web document models. The results were shown to correlate significantly with research productivity
in Taiwan but not in the Mainland, although in the latter case less reliable institutional data could have been the cause.
For Taiwan, this is the first evidence of a scholarly association with academic linking for a non-English speaking region.
It was then ascertained that the same link counts associated more strongly with scientific than social scientific research
productivity in Taiwan. This confirms the general assumption of greater Web use by the hard sciences. We then investigated
Taiwan-Mainland university cross-links, and found that although English is extensively used on the Web, there was no evidence
that it was the language of preference for informal scholarly communication between the two areas.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
9.
In the present study, attempts are made to extend the application of the mechanical model for the fatigue crack initiation (FCI) and the FCI life formula of metallic notched elements in laboratory air to those in the corrosive environment. The test results and analysis of the corrosion FCI (CFCI) life of aluminum alloys and Ti---6A1---4V show that the expression of the CFCI life obtained by modifying the FCI life formula in laboratory air can give a good fit to the test results of the CFCI life. The salt water (3.5% NaCl) environment has no effects on the CFCI resistant coefficient compared with the FCI resistant coefficient in laboratory air. However, 3.5% NaCl environment greatly decreases the CFCI threshold of aluminum alloy, but has little effect on the CFCI threshold of Ti---6A1---4V. The loading frequency ranging from 1 Hz to 10 Hz has no appreciable effect on the CFCI life, and thus, the CFCI threshold of aluminum alloys investigated. Hence, the expression for the CFCI life of metallic notched elements proposed in this study is a better one, which reveals a correlation between the CFCI life and the governing parameters, such as, the geometry of the notched elements, the nominal stress range, the stress ratio, the tensile properties and the CFCI threshold. However, this new expression of the CFCI life needs to be verified by more test results. 相似文献
10.
制作压力传感器时,在二氧化硅层上淀积多晶硅膜,既可利用优良的机械特性,又可保证压敏电阻与衬底间具有良好的绝缘性,由此可大大提高器件的温度特性。介绍了一种多晶硅压力传感器的原理和设计。实验结果表明,这类传感器具有灵敏度好,精度高等特点,电路工作范围为0-250℃,且具有良好的温度稳定性。 相似文献