全文获取类型
收费全文 | 9020篇 |
免费 | 361篇 |
国内免费 | 430篇 |
专业分类
电工技术 | 240篇 |
综合类 | 1029篇 |
化学工业 | 436篇 |
金属工艺 | 104篇 |
机械仪表 | 715篇 |
建筑科学 | 1116篇 |
矿业工程 | 310篇 |
能源动力 | 181篇 |
轻工业 | 289篇 |
水利工程 | 301篇 |
石油天然气 | 208篇 |
武器工业 | 34篇 |
无线电 | 634篇 |
一般工业技术 | 299篇 |
冶金工业 | 399篇 |
原子能技术 | 119篇 |
自动化技术 | 3397篇 |
出版年
2023年 | 15篇 |
2022年 | 49篇 |
2021年 | 66篇 |
2020年 | 83篇 |
2019年 | 70篇 |
2018年 | 73篇 |
2017年 | 74篇 |
2016年 | 104篇 |
2015年 | 147篇 |
2014年 | 483篇 |
2013年 | 561篇 |
2012年 | 618篇 |
2011年 | 837篇 |
2010年 | 620篇 |
2009年 | 505篇 |
2008年 | 548篇 |
2007年 | 710篇 |
2006年 | 641篇 |
2005年 | 566篇 |
2004年 | 522篇 |
2003年 | 526篇 |
2002年 | 430篇 |
2001年 | 308篇 |
2000年 | 284篇 |
1999年 | 236篇 |
1998年 | 188篇 |
1997年 | 124篇 |
1996年 | 89篇 |
1995年 | 70篇 |
1994年 | 53篇 |
1993年 | 33篇 |
1992年 | 22篇 |
1991年 | 18篇 |
1990年 | 11篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 7篇 |
1985年 | 22篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有9811条查询结果,搜索用时 31 毫秒
1.
2.
Biosolids reduction model by return activated sludge ozonation was validated by simulating nitrification data compiled from our pilot-scale and the literature studies. Then, a global sensitivity analysis (GSA) was performed to identify influential and non-influential parameters for biosolids reduction efficiency, change in specific nitrification activity (SNA), and alteration to expected nitrification stability. In general, the model outputs were sensitive to operational and ozone reaction parameters, but not to biochemical parameters. For operational parameters, mainly temperature and initial solids retention time (SRT) influenced all model outputs. For biosolids reduction, increase in the degradability of the influent COD decreased the reduction efficiency. For SNA, the changes were highly dependent on the influent TKN/COD ratio. Our findings also imply that the stability of the nitrification process in ozonated systems should be enhanced at constant MLVSS for warm temperatures, but could be reduced at temperatures below 12 °C and aerated SRTs below 10 days. 相似文献
3.
Hitoshi Muta 《Journal of Nuclear Science and Technology》2019,56(5):367-368
Recent activities in the field of Nuclear Operational Management and Nuclear Safety Engineering, the studies related to risk analysis methodology, design, and operational management, physical phenomena, and emergency preparedness and nuclear security, have been progressed. Especially, ‘risk analysis methodology’ and ‘design and operational management’ are the main categories of the field, in which more than half of published articles on Journal of Nuclear Science and Technology are related to these categories. 相似文献
4.
Risk allocation decisions are of critical importance in project management. The present study proposes an explanation for how risk allocation in a contract motivates a contractor to cooperate with a project owner. Theories of risk allocation and trust were used to motivate the research. Using a survey methodology, we collected data concerning 124 construction projects in China. We found that risk allocation influenced the contractor’s role behavior through the contractor’s feeling of being trusted but not the contractor’s trust in the owner. Feeling of being trusted partially mediated the effect of risk allocation on the contractor’s in-role (i.e., contractual) behavior and fully mediated the effect on extra-role behavior. The study introduces a social and psychological view of the impacts of risk allocation to the project and engineering management literature. We contribute to theory by arguing and demonstrating the mediating effect of trust on the relationship between risk allocation and contractor behavior. From a practical standpoint, we conclude that contractual risk allocation has a significant impact on building a trusting relationship between owners and contractors and that contractors who feel trusted perform both contractually mandated actions and actions external to the contract more diligently, resulting in the likelihood of improved outcomes for both parties. 相似文献
5.
Jean-Fran?ois Blais Nathalie Meunier Guy Mercier Patrick Drogui Rajeshwar Dayal Tyagi 《Canadian Metallurgical Quarterly》2004,130(5):516-525
This research is related to a preindustrial pilot scale study of the performance of the simultaneous sewage sludge digestion and metal leaching (SSDML) process for decontamination and stabilization of sewage sludge. Ten batch tests were carried out in two 4?m3 bioreactors under various conditions of operation. Results indicated that the addition of 1.0 to 1.5?g?S0/L, which is the equivalent of approximately 30 to 50?kg?S0 per tons dry sludge, is sufficient to obtain conditions of acidity (pH<2.5) and oxido-reduction potential greater than 500 mV necessary for an effective solubilization of toxic metals. The final average of metal solubilization in the output sludge during the SSDML process varied in the following ranges: 25–78% Cd, 9–32% Cr, 48–100% Cu, 77–99% Mn, 15–53% Ni, 12–47% Pb, and 66–100% Zn. The N, P, and K contents were also preserved in the decontaminated sludge. Moreover, the use of low concentrations of elemental sulfur makes it possible to obtain decontaminated sludge with a low total sulfur content (1.4–1.5% S) compatible with agricultural use. The suspended solids removal calculated for the SSDML process was slightly lower, (2.5±0.4)% volatile suspended solids per day, than those reached using standard aerobic digestion. Finally, the SSDML process was found to be effective in removing bad odors and in the destruction (99–100%) of indicator bacteria. 相似文献
6.
7.
8.
9.
张雅兵 《石油化工安全环保技术》2003,19(1):9-11
通过严格外来施工队伍和人员的安全管理,加强直接作业票证的管理,落实监护人职责,开展项目危险性分析,强化现场监督等手段,从而加强了检修现场的安全管理,保证系统停车检修的圆满完成。 相似文献
10.
我国放射性物质运输概况 总被引:1,自引:0,他引:1
本文介绍了我国放射性物质运输概况(除台湾省外)。目前,全国放射性物质货包的年运输最约10万件,总放射性活度为1.8PBq,运输的放射性同位素主要是~(131)I、~(32)P 和~(198)Au 等。承运人员的年剂量当量是相当低的,一般小于5mSv。由于十分重视放射性物质的安全运输,所以没有发生过严重事故。文中还讨论了放射性物质运输中的防护问题。 相似文献