全文获取类型
收费全文 | 103533篇 |
免费 | 2543篇 |
国内免费 | 1241篇 |
专业分类
电工技术 | 1844篇 |
技术理论 | 4篇 |
综合类 | 3351篇 |
化学工业 | 15010篇 |
金属工艺 | 5714篇 |
机械仪表 | 4247篇 |
建筑科学 | 3511篇 |
矿业工程 | 1134篇 |
能源动力 | 1691篇 |
轻工业 | 4700篇 |
水利工程 | 1564篇 |
石油天然气 | 1548篇 |
武器工业 | 131篇 |
无线电 | 11855篇 |
一般工业技术 | 18839篇 |
冶金工业 | 3674篇 |
原子能技术 | 435篇 |
自动化技术 | 28065篇 |
出版年
2024年 | 71篇 |
2023年 | 330篇 |
2022年 | 568篇 |
2021年 | 841篇 |
2020年 | 597篇 |
2019年 | 545篇 |
2018年 | 14924篇 |
2017年 | 13921篇 |
2016年 | 10458篇 |
2015年 | 1325篇 |
2014年 | 1167篇 |
2013年 | 1436篇 |
2012年 | 4304篇 |
2011年 | 10672篇 |
2010年 | 9255篇 |
2009年 | 6561篇 |
2008年 | 7785篇 |
2007年 | 8730篇 |
2006年 | 1175篇 |
2005年 | 2138篇 |
2004年 | 1747篇 |
2003年 | 1779篇 |
2002年 | 1066篇 |
2001年 | 552篇 |
2000年 | 708篇 |
1999年 | 647篇 |
1998年 | 593篇 |
1997年 | 490篇 |
1996年 | 492篇 |
1995年 | 338篇 |
1994年 | 316篇 |
1993年 | 224篇 |
1992年 | 183篇 |
1991年 | 162篇 |
1990年 | 125篇 |
1989年 | 97篇 |
1988年 | 87篇 |
1987年 | 52篇 |
1986年 | 46篇 |
1985年 | 37篇 |
1968年 | 44篇 |
1967年 | 34篇 |
1966年 | 43篇 |
1965年 | 45篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
George Ter-Stepanian 《Bulletin of Engineering Geology and the Environment》2002,61(3):197-205
The paper discusses the postulated suspension force, by which it is possible to explain some enigmatic phenomena observed
in different types of mass movements. This force is generated in thick suspensions as a result of friction between sinking
solid particles and static water. The suspension force is related to the seepage force but they have opposite directions.
Both forces form flow networks. Having explained the suspension force, the paper describes how this influences the movement
of material, particularly in debris flows. Enigmatic features and the mechanism of debris flows and lahars are explained by
virtue of the suspension force.
Electronic Publication 相似文献
73.
We consider the problem of rescheduling trains in the case where one track of a railway section consisting of two tracks
in opposing directions is closed due to construction activities. After presenting an appropriate model for this situation
we derive a polynomial algorithm for the subproblem of finding an optimal schedule with minimal latenesss if the subsequences
of trains for both directions outside the construction site are fixed. Based on this algorithm we propose a local search procedure
for the general problem of finding good schedules and report test results for some real world instances.
Received: December 8, 1999 / Accepted: May 2, 2001 相似文献
74.
Tan J.C. Crossley P.A. McLaren P.G. Hall I. Farrell J. Gale P. 《Power Delivery, IEEE Transactions on》2002,17(1):68-74
This paper describes a sequential tripping strategy used in a wide area back-up protection expert system (BPES) to combat situations in which protection relays have maloperated or information is missing. The BPES is an innovative back-up protection scheme designed to prevent the occurrence of widespread blackouts. The BPES evaluates the certainty that transmission lines are likely to be affected by the fault and uses a sequential tripping strategy to isolate the fault if a firm decision is not available due to maloperated relays and/or missing information. The mode of analysis and the sequential tripping strategy ensures that the BPES will clear a fault at minimum risk to the network. An example is included to demonstrate how the certainty factor based sequential tripping strategy is employed by the BPES to clear a fault which occurred on the South Western part of the UK National Grid System 相似文献
75.
Three interesterified vegetable oils (IVOs) prepared from palm, cottonseed, and olive oil, respectively, have been studied for application to Frankfurters. Beef fat (10%) was replaced by one of the IVOs at 20, 60 or 100%. Fatty acid composition of the lipid fraction in the Frankfurters and saturated/unsaturated ratios were established for all batches. We found that total or partial replacement of beef fat by IVOs did not lead to significant changes in appearance, colour, texture, flavour or sensory score. We conclude that IVOs may be successfully applied as beef fat substitutes in Frankfurters. 相似文献
76.
J-M Choe 《欧洲信息系统杂志》2002,11(2):142-158
This study empirically examined the organisational learning effects of the nonfinancial performance information provided by management accounting information systems (MAISs) under advanced manufacturing technology (AMT). In this study, a target costing system and the frequent and quick reporting of information were considered the facilitators of learning. First, we examined the relationships between AMT level and the amount of nonfinancial performance information produced by MAISs. The empirical results showed that there are significant positive relationships between the level of AMT and nonfinancial performance information. With a systems approach, we also proved the impact of the relationships among AMT levels, nonfinancial performance information and learning facilitators on the organisational performance of a firm. The results of our research suggest that under a high level of AMT, for the provision of information to result in an increase of performance through organisational learning, a target costing system must be introduced and a large amount of information should be provided frequently and quickly. The results of this study also showed that although AMT level may be low, fairly well-arranged facilitators and a moderately large amount of information may be necessary for the improvement of performance. In conclusion, effective organisational learning depends on the provision of relevant information as well as efficient learning support mechanisms. 相似文献
77.
78.
79.
80.
Less may not be more,but it still counts: The state of social capital in Yeoville,Johannesburg 总被引:2,自引:2,他引:0
Kirsten Harrison 《Urban Forum》2002,13(1):67-84