全文获取类型
收费全文 | 45951篇 |
免费 | 3794篇 |
国内免费 | 5531篇 |
专业分类
电工技术 | 2178篇 |
技术理论 | 68篇 |
综合类 | 5612篇 |
化学工业 | 6428篇 |
金属工艺 | 1150篇 |
机械仪表 | 2670篇 |
建筑科学 | 15781篇 |
矿业工程 | 1810篇 |
能源动力 | 1584篇 |
轻工业 | 1017篇 |
水利工程 | 2010篇 |
石油天然气 | 1611篇 |
武器工业 | 758篇 |
无线电 | 2058篇 |
一般工业技术 | 4471篇 |
冶金工业 | 1059篇 |
原子能技术 | 179篇 |
自动化技术 | 4832篇 |
出版年
2024年 | 217篇 |
2023年 | 790篇 |
2022年 | 1050篇 |
2021年 | 1418篇 |
2020年 | 1449篇 |
2019年 | 1109篇 |
2018年 | 1044篇 |
2017年 | 1266篇 |
2016年 | 1538篇 |
2015年 | 1624篇 |
2014年 | 4011篇 |
2013年 | 2860篇 |
2012年 | 3369篇 |
2011年 | 3593篇 |
2010年 | 2972篇 |
2009年 | 3035篇 |
2008年 | 2984篇 |
2007年 | 3598篇 |
2006年 | 3240篇 |
2005年 | 2919篇 |
2004年 | 2533篇 |
2003年 | 1913篇 |
2002年 | 1401篇 |
2001年 | 1077篇 |
2000年 | 917篇 |
1999年 | 702篇 |
1998年 | 493篇 |
1997年 | 434篇 |
1996年 | 361篇 |
1995年 | 297篇 |
1994年 | 227篇 |
1993年 | 177篇 |
1992年 | 158篇 |
1991年 | 84篇 |
1990年 | 72篇 |
1989年 | 63篇 |
1988年 | 47篇 |
1987年 | 30篇 |
1986年 | 20篇 |
1985年 | 24篇 |
1984年 | 31篇 |
1983年 | 22篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 18篇 |
1979年 | 9篇 |
1961年 | 4篇 |
1958年 | 4篇 |
1957年 | 6篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
The effect of pressure on combustion and heat transfer is analyzed. The research is based on the basic combustion and heat
transfer theorem. A correction for the heat calculation method for pressurized furnace is made on the basis of the normal
pressure case. The correction takes the effect of pressurizing into account. The results show that the correction is reasonable
and the method is applicable to combustion and heat transfer of the marine supercharged boiler. 相似文献
92.
B737机务CBT系统建设方案的探讨 总被引:3,自引:0,他引:3
张旭 《上海工程技术大学学报》2004,18(4):375-378
通过对AICC制订的CBT课件开发规范的探讨,阐述了CBT的基本概念和波音737飞机机务CBT的开发制作过程,以及利用Authorware开发软件制作多媒体课件的技术难点。 相似文献
93.
从工程前期、中期计量支付、责权利协调方面对工程项目中计量支付工作进行了介绍,并对各阶段的工作注意事项作了说明,指出做好计量支付工作是控制工程项目建设的关键环节。 相似文献
94.
A manufacturability evaluation decision model is formulated and analyzed based on fuzzy logic and multiple attribute decision-making under the concurrent engineering environment. The study emphasizes on the treatment of the linguistic and vagueness at the early product development stage. The study also considers the function integration of the total life cycle of a product. Hence, the integrated decision model covers the multi-level, multi-goal requirements of the products. Multiple criteria such as the goal space, the decision space, the function space, the development (i.e., product & process design) space, and the activity space, are then applied under different analysis of decision-making methods. For instances, the fuzzy multiple attribute decision-making (FMADM) combined with activity-based costing (ABC) can be used in the activity decision space. The fuzzy logic decision model can be applied in the goal decision space. The results of this study point out the importance of early decision making capability. An example of a high-pressure vessel is provided to demonstrate the proposed model for evaluating the manufacturability. 相似文献
95.
96.
结合某校教学楼基坑工程实践,对防止滑坡采取措施的有效性进行了总结,同时对滑坡出现的原因进行分析,提出了预防基坑滑坡应注意事项。 相似文献
97.
D. Roy 《International journal for numerical methods in engineering》2004,61(5):764-790
Sample pathwise numerical integration of noise-driven engineering dynamical systems cannot generally be performed beyond a limited level of accuracy, especially when the noise processes are modelled using (filtered) white noises. Recently, a locally transversal linearization (LTL) strategy has been proposed by the author (Proc Roy Soc London A 2001; 457 :539–566) for direct integration of deterministic and stochastic non-linear dynamical systems. The present effort is focussed on a host of extensions along with detailed theoretical error analyses of the linearization approach, especially as applied to problems in non-linear stochastic engineering dynamics. Thus, to begin with, estimates of local and global error orders in the basic LTL scheme are obtained separately for the displacement and velocity vectors when the system is driven either by a set of additive noises or by an arbitrary combination of (independently evolving) additive and multiplicative noises. Following this, a new family of higher-order LTL schemes is proposed in order to improve upon the basic LTL method and the associated error orders are established. A stepwise implementation of the lower- and higher-order versions of the LTL method, along with certain computational aspects, is also outlined. The proposed schemes are numerically illustrated, to a limited extent, for a single degree-of-freedom (SDOF) and a two degree-of-freedom (TDOF) non-linear engineering systems under additive and/or multiplicative white noise excitations. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
98.
Youngjoong Ko Sooyong Park Jungyun Seo Soonhwang Choi 《Information and Software Technology》2007,49(11-12):1128-1140
In order to efficiently develop large-scale and complicated software, it is important for system engineers to correctly understand users’ requirements. Most requirements in large-scale projects are collected from various stakeholders located in various regions, and they are generally written in natural language. Therefore, the initial collected requirements must be classified into various topics prior to analysis phases in order to be usable as input in several requirements analysis methods. If this classification process is manually done by analysts, it becomes a time-consuming task. To solve this problem, we propose a new bootstrapping method which can automatically classify requirements sentences into each topic category using only topic words as the representative of the analysts’ views. The proposed method is verified through experiments using two requirements data sets: one written in English and the other in Korean. The significant performances were achieved in the experiments: the 84.28 and 87.91 F1 scores for the English and Korean data sets, respectively. As a result, the proposed method can provide an effective function for an Internet-based requirements analysis-supporting system so as to efficiently gather and analyze requirements from various and distributed stakeholders by using the Internet. 相似文献
99.
Edmond P. Saliklis David P. Billington Anneliza W. Carmalt 《Canadian Metallurgical Quarterly》2007,13(2):72-77
This paper presents new aspects of Anton Tedesko’s design for an important thin shell concrete roof. The study of this roof results from the examination of original engineering drawings and calculations which we present with the goal of promoting a greater understanding of the structural design of a major figure in the tradition of 20th century building. 相似文献
100.
Prevention and Mitigation Strategies to Address Recent Brittle Fractures in Steel Bridges 总被引:1,自引:0,他引:1
Robert J. Connor Eric J. Kaufmann John W. Fisher William J. Wright 《Canadian Metallurgical Quarterly》2007,12(2):164-173
Brittle fracture results in unplanned loss of service, very costly repairs, concern regarding the future safety of the structure, and potential loss of life. These types of failures are most critical when there is no evidence of fatigue cracking leading up to the fracture and the fracture origin is concealed from view. Hence, the failure occurs without warning and the details are, essentially, noninspectable. In these cases, it appears desirable to take a proactive approach and introduce preventative retrofits to reduce the potential for future crack development. These efforts will help ensure that the likelihood of unexpected fractures is minimized. This paper examines the behavior of two bridge structures in which brittle fractures have developed in recent times, discusses the causes of the failures, and offers suggested design strategies for prevention and retrofit mitigation techniques. In situations where considerable uncertainty exists in the prediction of accumulated damage or in the ability to reliably inspect critical details, preemptive retrofit strategies appear to be highly desirable. 相似文献