全文获取类型
收费全文 | 154548篇 |
免费 | 13433篇 |
国内免费 | 7112篇 |
专业分类
电工技术 | 9677篇 |
技术理论 | 11篇 |
综合类 | 10254篇 |
化学工业 | 25086篇 |
金属工艺 | 9415篇 |
机械仪表 | 10306篇 |
建筑科学 | 13009篇 |
矿业工程 | 4814篇 |
能源动力 | 4578篇 |
轻工业 | 9775篇 |
水利工程 | 2704篇 |
石油天然气 | 10229篇 |
武器工业 | 1290篇 |
无线电 | 17412篇 |
一般工业技术 | 18166篇 |
冶金工业 | 7148篇 |
原子能技术 | 1722篇 |
自动化技术 | 19497篇 |
出版年
2024年 | 601篇 |
2023年 | 2562篇 |
2022年 | 4631篇 |
2021年 | 6547篇 |
2020年 | 4882篇 |
2019年 | 3969篇 |
2018年 | 4424篇 |
2017年 | 4958篇 |
2016年 | 4555篇 |
2015年 | 6238篇 |
2014年 | 7539篇 |
2013年 | 9066篇 |
2012年 | 9877篇 |
2011年 | 10553篇 |
2010年 | 9262篇 |
2009年 | 8723篇 |
2008年 | 8674篇 |
2007年 | 8300篇 |
2006年 | 8614篇 |
2005年 | 7423篇 |
2004年 | 4936篇 |
2003年 | 4586篇 |
2002年 | 4511篇 |
2001年 | 4047篇 |
2000年 | 3758篇 |
1999年 | 4123篇 |
1998年 | 3182篇 |
1997年 | 2689篇 |
1996年 | 2648篇 |
1995年 | 2176篇 |
1994年 | 1780篇 |
1993年 | 1203篇 |
1992年 | 1064篇 |
1991年 | 748篇 |
1990年 | 560篇 |
1989年 | 464篇 |
1988年 | 373篇 |
1987年 | 229篇 |
1986年 | 171篇 |
1985年 | 119篇 |
1984年 | 78篇 |
1983年 | 58篇 |
1982年 | 73篇 |
1981年 | 41篇 |
1980年 | 39篇 |
1979年 | 24篇 |
1978年 | 3篇 |
1965年 | 1篇 |
1959年 | 4篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Xia Haihong Zhao Zhixiang Li Jigen Shi Yongqian Han Yinlu Zhu Shengyun Xu Yongli Guan Xialing Cui Baoqun Fu Shinian 《Frontiers of Energy and Power Engineering in China》2007,1(2):135-140
The conceptual study on the accelerator driven system (ADS) that lasted for about five years ended in 1999 in China. As one
project of the National Basic Research Program of China (973 Program) in the energy domain, which is sponsored by the China
Ministry of Science and Technology (MOST), a five-year-program of fundamental research of ADS physics and related technology
was launched in 2000 and passed national review at the end of 2005. The China Institute of Atomic Energy (CIAE), the Institute
of High Energy Physics (IHEP), the Institute of Heavy Ion Physics in Peking University (PKU-IHIP) and other institutions jointly
carried out the research. The research activities were focused on HPPA physics and technology, reactor physics of external
source driven sub-critical assembly, nuclear data base and material study. For HPPA, a high current injector consisting of
an ECR ion source, LEBT and an RFQ accelerating structure of 3.5 MeV was built. In reactor physics study, a series of neutron
multiplication experimental study has been carried out and still being done. The VENUS facility has been constructed as the
basic experimental platform for neutronics study in ADS blanket. It’s a zero power sub-critical neutron multiplying assembly
driven by external neutron produced by a pulsed neutron generator. The theoretical, experimental and simulation study on nuclear
data, material properties and nuclear fuel circulation related to ADS is carrying on to provide the database for ADS system
analysis. The main results on ADS related researches will be reported. 相似文献
942.
428XL地震仪器系统成功实践了一种新的可控震源施工技术和方法——高保真可控震源采集技术(HFVS)。本质上,HFVS技术是以采集到的每台震源实际运动的信号来进行数据反演,替代了传统的以参考信号进行的互相关处理,从而有效地减少了谐波畸变对地震资料品质的影响。在实际施工时,HFVS技术采用多台震源以不同初始扫描相位同时激发,再将采集到的地震记录进行分离处理得到每台震源的大地脉冲响应,实现了高效采集条件下的可控震源单点激发。本文详细介绍了HFVS技术的基本原理,总结了高保真可控震源采集的施工特点及其对仪器采集设备的要求,并通过实例,介绍了利用428XL仪器先进的技术性能实现高保真可控震源三维地震采集的方法和经验。 相似文献
943.
944.
本文针对一典型的电液传动装置提出了一种控制器.该控制器实际上是带有少量外围设
备的单板机.文中叙述了控制系统模型、理论分析、综合的方法以及仿真研究和在线控制实验
的结果. 相似文献
945.
This paper presents an approach to the evaluation of reservoir models using transient pressure data. Braided fluvial sandstones exposed in cliffs in SW England were studied as the surface equivalent of the Triassic Sherwood Sandstone, a reservoir unit at the nearby Wytch Farm oilfield. Three reservoir models were built; each used a different modelling approach ranging in complexity from stochastic pixel‐based modelling using commercially available software, to a spreadsheet random number generator. In order to test these models, numerical well test simulations were conducted using sector models extracted from the geological models constructed. The simulation results were then evaluated against the actual well test data in order to find the model which best represented the field geology. Two wells at Wytch Farm field were studied. The results suggested that for one of the sampled wells, the model built using the spreadsheet random number generator gave the best match to the well test data. In the well, the permeability from the test interpretation matched the geometric average permeability. This average is the “correct” upscaled permeability for a random system, and this was consistent with the random nature of the geological model. For the second well investigated, a more complex “channel object” model appeared to fit the dynamic data better. All the models were built with stationary properties. However, the well test data suggested that some parts of the field have different statistical properties and hence show non‐stationarity. These differences would have to be built into the model representing the local geology. This study presents a workflow that is not yet considered standard in the oil industry, and the use of dynamic data to evaluate geological models requires further development. The study highlights the fact that the comparison or matching of results from reservoir models and well‐test analyses is not always straightforward in that different models may match different wells. The study emphasises the need for integrated analyses of geological and engineering data. The methods and procedures presented are intended to form a feedback loop which can be used to evaluate the representivity of a geological model. 相似文献
946.
蠕变过程中碳化物形貌,类型,数量和分布状态的变化直接影响着材料的高温性能,因而在材料的蠕变得到了广泛的重视,介绍了一种在碳膜萃取复型样品上利用H-800透射电子显微镜的双倾样品台进行了大角度倾转,来观察碳化物形貌并鉴定其类型的试验方法。 相似文献
947.
本文论述了双曝光全息干涉测量技术的基本理论和实际应用方法。并进而推论了条纹形状和物体微小位移之间的定量关系。最后给出了实验装置和实验结果。 相似文献
948.
SW233 PIN驱动器自动测试系统的研制 总被引:1,自引:0,他引:1
介绍了一种集成电路自动测试系统,该系统采用计算机并口作通信接口,用VB6编程,实现了对外围测试电路的控制,用IEEE-488接口卡控制测试仪器,可对SW233电路的36个参数进行自动测试,并将测试结果自动保存在数据库中。该测试系统具有自动化程度高、操作方便、测试结果精确等特点。 相似文献
949.
铜电解精炼过程中砷、锑、铋的危害及脱除方式的进展 总被引:6,自引:1,他引:5
在铜电解精炼过程中 ,砷、锑、铋等杂质 ,尤其是锑、铋 ,一直来被人们认为是对阴极铜生产、影响阴极铜质量的最为有害的元素。本文结合贵冶历年的生产实践来讨论砷、锑、铋等杂质在阴极铜生产过程中的危害以及脱除方式的进展。 相似文献
950.
本文讨论了非硅微机械工艺和微绞链的研制工艺。我们研制的非硅表面微机械工艺采用两次或三次掩模电镀层,聚酰亚胺和光刻胶分别作为底层和第二、第三层的牺牲层。用这套工艺,研制成功了三种不同种类的微绞链。微绞链能在基片表面作0—180度自由转动。 相似文献