全文获取类型
收费全文 | 2227篇 |
免费 | 92篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
化学工业 | 887篇 |
金属工艺 | 77篇 |
机械仪表 | 30篇 |
建筑科学 | 26篇 |
矿业工程 | 9篇 |
能源动力 | 27篇 |
轻工业 | 178篇 |
水利工程 | 15篇 |
石油天然气 | 49篇 |
无线电 | 93篇 |
一般工业技术 | 465篇 |
冶金工业 | 243篇 |
原子能技术 | 38篇 |
自动化技术 | 163篇 |
出版年
2023年 | 38篇 |
2022年 | 212篇 |
2021年 | 199篇 |
2020年 | 69篇 |
2019年 | 53篇 |
2018年 | 70篇 |
2017年 | 79篇 |
2016年 | 81篇 |
2015年 | 61篇 |
2014年 | 108篇 |
2013年 | 85篇 |
2012年 | 93篇 |
2011年 | 106篇 |
2010年 | 63篇 |
2009年 | 72篇 |
2008年 | 84篇 |
2007年 | 62篇 |
2006年 | 54篇 |
2005年 | 48篇 |
2004年 | 34篇 |
2003年 | 33篇 |
2002年 | 38篇 |
2001年 | 29篇 |
2000年 | 22篇 |
1998年 | 46篇 |
1997年 | 32篇 |
1996年 | 18篇 |
1995年 | 14篇 |
1994年 | 12篇 |
1993年 | 19篇 |
1992年 | 24篇 |
1991年 | 14篇 |
1990年 | 14篇 |
1989年 | 19篇 |
1987年 | 11篇 |
1986年 | 22篇 |
1984年 | 15篇 |
1981年 | 11篇 |
1980年 | 17篇 |
1979年 | 17篇 |
1978年 | 13篇 |
1977年 | 22篇 |
1976年 | 16篇 |
1975年 | 16篇 |
1974年 | 13篇 |
1973年 | 11篇 |
1972年 | 14篇 |
1971年 | 11篇 |
1969年 | 10篇 |
1968年 | 12篇 |
排序方式: 共有2321条查询结果,搜索用时 13 毫秒
11.
Conductivities of composites filled with different carbon fibers having different heat treatment temperatures (HTT) have been studied. It is shown that conductivity realization coefficient decreases with the increase of HTT. © 1993 John Wiley & Sons, Inc. 相似文献
12.
Kalinnik Natalia Kiesel Robert Rauber Thomas Richter Marcel Rünger Gudula 《The Journal of supercomputing》2021,77(4):3484-3515
The Journal of Supercomputing - Scientific application codes are often long-running time- and energy-consuming parallel codes, and the tuning of these methods towards the characteristics of a... 相似文献
13.
S. A. Kutseba A. A. Shevchenko P. A. Chukalovskii P. A. Butyagin É. A. Mal'vinov 《Fibre Chemistry》1988,20(1):59-61
Conclusions The possibility of using polymeric transporting cylinders instead of the traditional rubber-coated ones has been investigated. The surface of the cylinders has a high hardness, and is resistant to the abrasive action of viscose textile yarn or knives for cutting off tow.The results of laboratory and manufacturing studies permit one to recommend polymeric transporting cylinders for equipping PNSh serially produced machines.Translated from Khimicheskie Volokna, No. 1, pp. 40–41, January–February, 1988. 相似文献
14.
15.
This paper reports on a case study of a teacher from a technical education institution who explored the educational affordances of PDA technology over a period of six months. Based on this teacher’s perspectives, the study was designed to inform our own understanding of educational affordances of this new and emerging technology. Understanding of educational affordances is important in the context of planning a suitable intervention to support pedagogically effective integration of PDA technology. The study explicated a set of five affordances of PDA technology: as a multimedia-access tool, connectivity tool, capture tool, representational tool and analytical tool. We call on further research to expand this set into a more comprehensive collage of educational affordances of PDA technology. 相似文献
16.
Classification of a video stream is an essential preliminary step to estimate the bit loss when the video stream is transmitted over a communication network. In this paper, we classify the video frames by the average frame size and estimate the bit loss for each class when the bitrate exceeds the capacity of the bottleneck link. The video stream under study is encoded using the explicit slice-based H.264/AVC encoding scheme. This scheme reduces the burstiness of regular H.264/AVC encoded video by removing the traditional GOP structure. Instead, a repetitive combination of intracoded and predicted slices is employed, thereby introducing a specific dependence structure in the video data. We consider a bufferless model of the communication system and evaluate the channel capacity required to give a maximum allowed loss rate for each class.Due to the high variability, non-stationarity and non-homogeneity of the underlying video data, the obtained classes are checked regarding the dependence and distribution structure of the data. The high quantiles of the losses are estimated for each class. 相似文献
17.
When using an unstructured mesh for device geometry, the ensemble Monte Carlo simulations of semiconductor devices may be affected by unwanted self-forces resulting from the particle-mesh coupling. We report on the progress in minimisation of the self-forces on arbitrary meshes by showing that they can be greatly reduced on a finite element mesh with proper interpolation functions. The developed methodology is included into a self-consistent finite element 3D Monte Carlo device simulator. Minimising of the self-forces using the proper interpolation functions is tested by simulating the electron transport in a 10 nm gate length, 6.1 nm body thick, double gate metal-oxide-semiconductor field-effect transistor (MOSFET). We demonstrate the reduction in the self-force and illustrate the practical distinction by showing I-V characteristics for the device. 相似文献
18.
Spatial generalization and aggregation of massive movement data 总被引:3,自引:0,他引:3
Andrienko N Andrienko G 《IEEE transactions on visualization and computer graphics》2011,17(2):205-219
Movement data (trajectories of moving agents) are hard to visualize: numerous intersections and overlapping between trajectories make the display heavily cluttered and illegible. It is necessary to use appropriate data abstraction methods. We suggest a method for spatial generalization and aggregation of movement data, which transforms trajectories into aggregate flows between areas. It is assumed that no predefined areas are given. We have devised a special method for partitioning the underlying territory into appropriate areas. The method is based on extracting significant points from the trajectories. The resulting abstraction conveys essential characteristics of the movement. The degree of abstraction can be controlled through the parameters of the method. We introduce local and global numeric measures of the quality of the generalization, and suggest an approach to improve the quality in selected parts of the territory where this is deemed necessary. The suggested method can be used in interactive visual exploration of movement data and for creating legible flow maps for presentation purposes. 相似文献
19.
The need to recover a train driver schedule occurs during major disruptions in the daily railway operations. Based on data from the Danish passenger railway operator DSB S-tog A/S, a solution method to the train driver recovery problem (TDRP) is developed. The TDRP is formulated as a set partitioning problem. We define a disruption neighbourhood by identifying a small set of drivers and train tasks directly affected by the disruption. Based on the disruption neighbourhood, the TDRP model is formed and solved. If the TDRP solution provides a feasible recovery for the drivers within the disruption neighbourhood, we consider that the problem is solved. However, if a feasible solution is not found, the disruption neighbourhood is expanded by adding further drivers or increasing the recovery time period. Fractional solutions to the LP relaxation of the TDRP are resolved with a constraint branching strategy using the depth-first search of the Branch & Bound tree. The LP relaxation of the TDRP possesses strong integer properties. We present test scenarios generated from the historical real-life operations data of DSB S-tog A/S. The numerical results show that all but one tested instances produce integer solutions to the LP relaxation of the TDRP and solutions are found within a few seconds. 相似文献
20.
In this paper we study parallel batch scheduling problems with bounded batch capacity and equal-length jobs in a single and
parallel machine environment. It is shown that the feasibility problem 1|p-batch,b<n,r
j
,p
j
=p,C
j
≤d
j
|− can be solved in O(n
2) time and that the problem of minimizing the maximum lateness can be solved in O(n
2log n) time. For the parallel machine problem P|p-batch,b<n,r
j
,p
j
=p,C
j
≤d
j
|− an O(n
3log n)-time algorithm is provided, which can also be used to solve the problem of minimizing the maximum lateness in O(n
3log 2
n) time. 相似文献