全文获取类型
收费全文 | 686篇 |
免费 | 53篇 |
国内免费 | 37篇 |
专业分类
电工技术 | 5篇 |
综合类 | 51篇 |
化学工业 | 8篇 |
金属工艺 | 3篇 |
机械仪表 | 16篇 |
建筑科学 | 59篇 |
矿业工程 | 31篇 |
能源动力 | 1篇 |
轻工业 | 4篇 |
水利工程 | 3篇 |
石油天然气 | 62篇 |
武器工业 | 1篇 |
无线电 | 88篇 |
一般工业技术 | 52篇 |
冶金工业 | 5篇 |
原子能技术 | 228篇 |
自动化技术 | 159篇 |
出版年
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 21篇 |
2015年 | 18篇 |
2014年 | 23篇 |
2013年 | 32篇 |
2012年 | 29篇 |
2011年 | 51篇 |
2010年 | 38篇 |
2009年 | 44篇 |
2008年 | 36篇 |
2007年 | 52篇 |
2006年 | 35篇 |
2005年 | 24篇 |
2004年 | 26篇 |
2003年 | 23篇 |
2002年 | 17篇 |
2001年 | 26篇 |
2000年 | 12篇 |
1999年 | 11篇 |
1998年 | 17篇 |
1997年 | 10篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 14篇 |
1993年 | 25篇 |
1992年 | 24篇 |
1991年 | 16篇 |
1990年 | 8篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1981年 | 1篇 |
排序方式: 共有776条查询结果,搜索用时 0 毫秒
1.
Kevin Yale Teichman 《Indoor air》1994,4(3):202-211
Deciding between the different policy approaches available for reducing human exposures to indoor pollutants is an exceptionally complex task. These options can range from waiting until more definitive information is available to enacting regulatory standards, with many variations in between. This paper presents some of the factors policy-makers must consider in establishing indoor air quality policies, and the role researchers should play in ensuring that indoor air policies are based on the best available scientific information. 相似文献
2.
3.
Air cleaning as a means of mitigating the risks arising from exposure to indoor radon progeny has been evaluated in a single-family house in the north eastem US. using an automated, semi-continuous activity-weighted size distribution measurement system. The measurements included radon concentration, condensation nuclei count, and activity-weighted size distribution of radon decay products. Measurements were made in the house with and without an operating air filtration system and with various particle sources common to normal indoor activities operating. Aerosols were generated by running water in a shower, candle burning, cigarette smoking, vacuuming, opening doors, and cooking. Using a room model, the changes in attachment rates, average attachment diameters, and deposition rates of the unattached fraction with and without the air cleaning system were calculated. In the presence of active aerosol sources, the air filtration unit typically reduced the concentration of particles within the hour following the end of particle generation. After candle burning, cigarette smoking, and vacuuming in the bedroom, the reductions of PAEC by air filtration are about 60% with the air filtration system operating in the bedroom. During cooking in the kitchen, the reductions of PAEC in the bedroom with the air filtration system were about 40%. However, for all cases the dose reductions were smaller than the particle and PAEC reductions. For those particles that were generated within the bedroom, there was a 20% to 50% reduction in dose. In the case of cooking where the door was open and particles infiltrated from the rest of the house, the dose reduction was only 5% on average and appears to be insignificant. Thus, the dose reductions were h e r than the reductions in activity concentration, but there were no cases where the estimated dose actually increased. 相似文献
4.
Soils and rocks are the predominant source of indoor radon (Rn) in southern Belgium. We have studied the correlations between geological features and indoor Rn concentrations using an indoor Rn data set of approx. 1700 short-term measurements. The sediments in the study region are divided into 11 geological series or 43 stages and 16 rock types. The results show a striking relation between indoor Rn concentration and the geological factors. 相似文献
5.
6.
本文测量了某铀矿不同工种的56名矿工下矿井作业前的呼出气中的~(222)Rn浓度,并由此估算了他们体内的~(226)Ra 负荷量。按不同工种的人数加权,呼出气中的~(222)Rn 浓度平均值为34.1Bqm~(-3),体内~(226)Ra 负荷量的均值为1.95kBq。同时还对9名休息了2天的和2名离开井下作业3—4年的矿工以及12名来下过矿井的本矿工人呼出气中氡浓度进行了测量,由此估算出其体内~(226)Ra 负荷量的均值分别为1.11、0.94和0.17kBq。 相似文献
7.
地热、温泉水利用中氡的防护 总被引:2,自引:0,他引:2
地热作为一种比较经济、方便的新能源的同时,也给公众和环境带来辐射影响。本文介绍了地热和温泉水中~(222)Rn 的放射性水平及其对人体健康的影响,对地热、温泉水利用中氡的防护措施提出了一些建议。 相似文献
8.
狗经氡子体暴露后血、毛中~(210)Pb 和~(210)Po 含量的动态变化 总被引:1,自引:1,他引:0
本文叙述了实验狗经氡子体暴露后血、毛中~(210)Po、~(210)Pb 含量、~(210)po/~(210)Pb 比率及血中~(210)Po,~(210)Pb 排出的动态变化。 相似文献
9.
本文简要介绍了液闪测氡中氡气自闪烁杯泄漏的实验结果。实验中对三种玻璃闪烁杯盖的密封性能作了检查,结果表明,这三种闪烁杯均不能满足液闪法测氡中对氡的密封要求。采用一层1mm 厚的橡胶垫片和一层0.01mm 厚的铝化聚脂膜作衬垫,代替原来的聚乙烯或纸板衬垫,解决了其中两种闪烁杯的氡气泄漏问题。建议在使用商品闪烁杯测氡时,应首先检查其对氡的密封性,必要时需采取补救措施,以保证测量结果的可靠性。 相似文献
10.
为满足实验室对一般氡测量仪器的刻度需要,设计了能够实现在脉冲模式、恒定模式和连续模式三种模式下自动控制、自动监测的氡测量刻度装置,并对装置进行了稳定性和可靠性试验。试验结果表明,该装置可为氡及其子体的研究以及其测量仪器的标定提供一个可调节、具有稳定氡浓度的环境。 相似文献