全文获取类型
收费全文 | 800篇 |
免费 | 54篇 |
国内免费 | 52篇 |
专业分类
电工技术 | 25篇 |
技术理论 | 1篇 |
综合类 | 19篇 |
化学工业 | 8篇 |
金属工艺 | 2篇 |
机械仪表 | 11篇 |
建筑科学 | 298篇 |
矿业工程 | 3篇 |
能源动力 | 52篇 |
轻工业 | 6篇 |
水利工程 | 50篇 |
石油天然气 | 3篇 |
武器工业 | 1篇 |
无线电 | 51篇 |
一般工业技术 | 20篇 |
冶金工业 | 99篇 |
原子能技术 | 6篇 |
自动化技术 | 251篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 22篇 |
2020年 | 25篇 |
2019年 | 21篇 |
2018年 | 17篇 |
2017年 | 24篇 |
2016年 | 25篇 |
2015年 | 32篇 |
2014年 | 47篇 |
2013年 | 63篇 |
2012年 | 48篇 |
2011年 | 75篇 |
2010年 | 55篇 |
2009年 | 70篇 |
2008年 | 54篇 |
2007年 | 68篇 |
2006年 | 48篇 |
2005年 | 44篇 |
2004年 | 39篇 |
2003年 | 26篇 |
2002年 | 29篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有906条查询结果,搜索用时 15 毫秒
1.
2.
数字签名通常作为不可反驳的密码学证据用于解决电子交易中的纷争,但是其可信的时间戳和证书撤销服务在实际使用中代价很高。免撤销公钥框架作为一种新的PKI使得终端用户可以控制他自己的公钥证书的有效性,使验证证书不需要折回到CA去获取证书撤销信息.从而降低其使用代价。 相似文献
3.
Shift in thinking to address the 21st century hunger gap 总被引:1,自引:1,他引:0
Malin Falkenmark 《Water Resources Management》2007,21(1):3-18
The present water policy debate is dominated by the 30 yr old mission to secure water supply and sanitation to all people.
The water needed to produce a nutritionally acceptable diet for one person is however 70 times as large as the amount needed
for domestic water supply. The food security dilemma is largest in arid climate regions, a situation constituting a formidable
challenge. It is suggested that an additional 5 600 km3/yr of consumptive water use will be needed to produce an adequate amount of food by 2050 – i.e almost a doubling of today’s
consumptive use of 6800 km3/yr. Past misinterpretations and conceptual deficiencies show the importance of a shift in thinking. Combining the scale of
the challenge and the time scale of the efforts to feed humanity and eradicate hunger leads to an impression of great urgency.
This urgency strengthens the call for international research both for supporting agricultural upgrading, and for much better
handling of issues of environmental sustainability. What stands out is the need of a new generation of water professionals,
able to handle complexity and able to incorporate water implications of land use and of ecosystem health in integrated water
resources management. It will for those reasons be essential and urgent to upgrade the educational system to producing this
new generation. 相似文献
4.
5.
The infrastructure renewal program at MIT consists of a large number of projects with an estimated budget that could approach $1 billion. Infrastructure renewal at the Massachusetts Institute of Technology (MIT) is the process of evaluating and investing in the maintenance of facility systems and basic structure to preserve existing campus buildings. The selection and prioritization of projects must be addressed with a systematic method for the optimal allocation of funds and other resources. This paper presents a case study of a prioritization method utilizing multi-attribute utility theory. This method was developed at MIT's Department of Nuclear Engineering and was deployed by the Department of Facilities after appropriate modifications were implemented to address the idiosyncrasies of infrastructure renewal projects and the competing criteria and constraints that influence the judgment of the decision-makers. Such criteria include minimization of risk, optimization of economic impact, and coordination with academic policies, programs, and operations of the Institute. A brief overview of the method is presented, as well as the results of its application to the prioritization of infrastructure renewal projects. Results of workshops held at MIT with the participation of stakeholders demonstrate the feasibility of the prioritization method and the usefulness of this approach. 相似文献
6.
目前国家环保部正在开展的国家环境信息与统计能力建设项目中,采用数字证书为业务系统提供强身份认证服务。详细论述了数字证书在环保部的应用模式,指出了今后的工作方向,同时也指出了现有应用模式的不足之处。 相似文献
7.
《The Electricity Journal》2021,34(7):107000
Carbon capture utilization and storage is an important technology option to rapidly and profoundly decarbonize the power sector, but will not deploy without substantial incentives or regulation. Assessment of U.S. policy options reveals that current incentives only partially close the finance gap and are most sensitive to fuel type and ownership structure. Recent proposed legislation would in some designs attract private investment for many projects, leading to widespread deployment of CCUS in the power sector. Additional constraints and concerns (including technology options and presence of CO2 infrastructure) could play an important secondary role. This study discusses the specific US incentive policies that can provide investors and lenders with net cash flows that are adequate to attract private capital to CCUS power projects in the US. 相似文献
8.
为了有效解决移动支付信息安全问题,在分析和研究无线应用协议(WAP)、公开密钥基础设施(WPKI)和移动网络安全威胁的基础上,提出了一种基于WAP和WPKI技术的移动支付安全解决方案。该方案通过对WAP和WPKI体系结构和优化性的分析,确定了基于WAP和WPKI的移动支付体系结构模型,并对安全支付系统功能模块进行了详细的设计。通过分析表明,该解决方案可为移动支付提供加密、认证等安全服务,为移动网络中的安全支付提供了较好的安全保障。 相似文献
9.
现有PKI、IBC认证技术与SSL/TLS通信协议已不能满足当今网络空间新兴信息产业的毫秒级信息安全需求。针对新兴信息产业的毫秒级通信安全问题,以CFL为原点技术,并基于CFL_BLP模型给出CFL SSL协议及其形式化描述,从协议层面上证明该协议可实现毫秒级双向认证、通信的机密性和完整性保护、自主可控以及防止中间人攻击等信息安全属性。实验结果表明,与SSL/TLS协议相比,该协议的可用性和安全性更高,且能够满足各种新兴信息产业通信机制的毫秒级信息安全需求。 相似文献
10.
为了有效解决广播加密系统中的密钥泄漏和密钥管理的问题,提出了一个新的实用的基于身份的广播加密方案。利用超椭圆曲线上的双线性对构造广播加密和解密算法,节省了广播通信传输带宽。引入了密钥自我强化保护机制,在分配用户密钥时通过用户的机密信息计算其解密密钥,降低了用户为保护自己的利益而泄漏其密钥的可能性。证明了方案在扩展的k元BDHI假设下对抗k用户合谋攻击的安全性 相似文献