首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   309篇
  免费   2篇
  国内免费   6篇
电工技术   2篇
综合类   2篇
化学工业   7篇
金属工艺   10篇
机械仪表   5篇
建筑科学   6篇
能源动力   1篇
轻工业   17篇
武器工业   1篇
无线电   5篇
一般工业技术   22篇
冶金工业   231篇
原子能技术   4篇
自动化技术   4篇
  2020年   2篇
  2019年   1篇
  2018年   3篇
  2017年   2篇
  2016年   1篇
  2015年   2篇
  2014年   4篇
  2013年   12篇
  2012年   5篇
  2011年   2篇
  2010年   3篇
  2009年   6篇
  2008年   4篇
  2007年   4篇
  2006年   4篇
  2005年   5篇
  2004年   5篇
  2003年   4篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1999年   9篇
  1998年   64篇
  1997年   41篇
  1996年   23篇
  1995年   17篇
  1994年   14篇
  1993年   14篇
  1992年   2篇
  1991年   3篇
  1990年   8篇
  1989年   4篇
  1988年   6篇
  1987年   4篇
  1986年   2篇
  1985年   1篇
  1982年   1篇
  1981年   2篇
  1980年   4篇
  1978年   1篇
  1977年   8篇
  1976年   12篇
  1975年   1篇
  1956年   1篇
  1954年   1篇
排序方式: 共有317条查询结果,搜索用时 15 毫秒
1.
2.
A new algorithm for overcoming the problem of incidental cancellation and improving the convergence behaviour of large partially adaptive arrays is proposed and investigated. The algorithm uses an auxiliary adaptive source tracker to separate individual sources in the environment before using the resulting outputs to cancel unwanted jamming picked up through the main beam of the system. Because the source tracker's outputs are roughly orthogonal in the steady state and the positions of sources of significant powers are available, the algorithm possesses fast convergence behaviour and solves the problem of incidental cancellation in the most natural manner by adding back the desired signal to the canceller output if the former is cancelled during the adaptation process. In addition, the algorithm has about the same computational complexity as partially adaptive generalized sidelobe cancellers using steepest descent based algorithms.  相似文献   
3.
传统中药是现代生活健康的宝库,其功效在保健及慢性疾病的治疗方面尤其显著,并已备受世界重视.要成功将中药引进世界市场,最基本要求是要从科学方法去证明其效用及安全性;更重要是依从传统中医学对复方应用的要求去作研究.本文陈述了我们对传统中药古方"生脉散"研究及开发抗氧化健康食品的经验.透过现代生化及药理技术,我们发现"生脉散"中的五味子含丰富的抗氧化活性成分,为传统中医学利用"生脉散"治疗心脏病提供了理论依据.  相似文献   
4.
A simple model is presented for the negative drain current transients observed in GaAs MESFETs when subjected to ionizing radiation. The two dominant mechanisms are proposed to be electron trapping under the Schottky gate and in the neutral semi-insulating substrate. The model is suitable for the design and evaluation of radiation-resistant GaAs MESFET integrated circuits using common electrical simulators such as SPICE3.  相似文献   
5.
6.
The extinction point of spinach was <0.4% but above 0.2% O2 at 0° and 5°C. Respiration rates were ~2.3 times greater at 5°C than at 0°C and were similar among cultivars. In 0.8% O2 atmosphere, O2 uptake of three cultivars was reduced by an average of 53% and CO2 production was reduced by 35% relative to those stored in air. Deterioration of leaves was reduced by 30 to 54%, while weight loss, color and chlorophyll content were not affected by the 0.8% O2 atmosphere. Thus O2 could be allowed to be depleted to 0.8% in modified atmosphere packaging without quality loss due to anoxia.  相似文献   
7.
通过测定32种多硝基芳烃的静电火花感度,建立了50%发火能量EES与爆速平方值的关系式。试式不仅体现出Evans-Planyi-Semenov关系,而且 起爆、初始分解或由静电火花引起的能量转换过程中多硝基化合物分子初始分裂时化学是的同一性。但电火花能转至分子反应中心的方式还不茂清楚  相似文献   
8.
9.
To clean the exhaust emissions as one of the most important tasks in pollution control, a study on the treatment of engine emissions with discharge assistance was reported. A DBD plasma source shaped in grid and cylinder was examined in different engine operational modes to reduce the NOX content of diesel engine exhaust. The composition of the exhaust gases and chemical reactions initiated by the discharge were analyzed. The discharge frequency had a crucial impact on the device’s performance and gas treatment. The voltages applied to the discharge gap could alter the chemical reactions occurring in the treated gases, which were indicated by the NO to NO2 ratio. The operation of the system was studied at frequencies ranging from 400 Hz to 16 kHz.  相似文献   
10.
Presentation of 11 cases of retroperitoneal sarcoma. Mean time from the beginning of symptoms to diagnosis is 6 months. The primary complementary study is CT. Surgery was performed in all cases, using complete resection in 6 cases, and partial resection in 5. Ten patients relapsed. 9 of which were treated with surgical rescue, in one or more occasions; chemotherapy was added in 6 cases and radiotherapy in 7. Survival at five years is 68%, with a mean follow-up of 66 months.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号