全文获取类型
收费全文 | 88984篇 |
免费 | 6578篇 |
国内免费 | 3907篇 |
专业分类
电工技术 | 3096篇 |
技术理论 | 19篇 |
综合类 | 7179篇 |
化学工业 | 18994篇 |
金属工艺 | 7576篇 |
机械仪表 | 5520篇 |
建筑科学 | 6432篇 |
矿业工程 | 3838篇 |
能源动力 | 2331篇 |
轻工业 | 9425篇 |
水利工程 | 1402篇 |
石油天然气 | 3794篇 |
武器工业 | 608篇 |
无线电 | 3944篇 |
一般工业技术 | 7615篇 |
冶金工业 | 7880篇 |
原子能技术 | 478篇 |
自动化技术 | 9338篇 |
出版年
2024年 | 360篇 |
2023年 | 953篇 |
2022年 | 1868篇 |
2021年 | 2341篇 |
2020年 | 2692篇 |
2019年 | 1957篇 |
2018年 | 1706篇 |
2017年 | 2208篇 |
2016年 | 2690篇 |
2015年 | 2835篇 |
2014年 | 5372篇 |
2013年 | 5518篇 |
2012年 | 6377篇 |
2011年 | 6664篇 |
2010年 | 5084篇 |
2009年 | 5053篇 |
2008年 | 4352篇 |
2007年 | 5788篇 |
2006年 | 5666篇 |
2005年 | 4889篇 |
2004年 | 4197篇 |
2003年 | 3778篇 |
2002年 | 3263篇 |
2001年 | 2772篇 |
2000年 | 2279篇 |
1999年 | 1851篇 |
1998年 | 1424篇 |
1997年 | 1086篇 |
1996年 | 986篇 |
1995年 | 773篇 |
1994年 | 631篇 |
1993年 | 428篇 |
1992年 | 362篇 |
1991年 | 285篇 |
1990年 | 191篇 |
1989年 | 156篇 |
1988年 | 117篇 |
1987年 | 75篇 |
1986年 | 69篇 |
1985年 | 47篇 |
1984年 | 51篇 |
1983年 | 52篇 |
1982年 | 24篇 |
1981年 | 22篇 |
1980年 | 26篇 |
1979年 | 17篇 |
1978年 | 11篇 |
1977年 | 16篇 |
1959年 | 12篇 |
1951年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
研究了热传导方程的通解,进而提出激光热源形成的微观机理和热源形成过程的三个理论计算式。对激光热效应的应用具有指导意义。 相似文献
72.
The authors highlight several possible ways in which the construction industry could lower present emissions of the greenhouse gas, carbon dioxide. It is an excellent discussion document and is recommended reading. 相似文献
73.
从实践上论述了UHE电弧炉炼钢的工艺特点,提出UHE电炉的“新三期”的新观点,并作了定量的描述;对正在发展中的UHE电炉工艺与设备提出了策略性的意见. 相似文献
74.
Batch process industries are characterized by complex precedence relationships between operations, which renders the estimation
of an acceptable workload very difficult. A detailed schedule based model can be used for this purpose, but for large problems
this may require a prohibitive large amount of computation time. We propose a regression based model to estimate the makespan
of a set of jobs. We extend earlier work based on deterministic processing times by considering Erlang-distributed processing
times in our model. This regression-based model is used to support customer order acceptance. Three order acceptance policies
are compared by means of simulation experiments: a scheduling policy, a workload policy and a regression policy. The results
indicate that the performance of the regression policy can compete with the performance of the scheduling policy in situations
with high variety in the job mix and high uncertainty in the processing times.
Correspondence to: C.V. Ivanescu 相似文献
75.
光刻胶灰化工艺与深亚微米线条的制作 总被引:5,自引:1,他引:4
随着器件尺寸的缩小,细线条的制作成为很关键的工艺,普通光学光刻已接近其分辨率的极限,而电子束光刻和X射线光刻技术复杂、费用昂贵。本文对光刻胶灰化工艺进行了分析和研究,并应用此工艺进行了深亚微米线条的制作,在普通光学光刻机上制作出宽度小于0.25μm细线条。我们已将此工艺成功地应用在深亚微米MOSFET的制作中。 相似文献
76.
77.
78.
介绍了高上山成型法的工艺特点及理论上的可行性和实践中的可靠性,此方法能有效地解决薄钢带波浪状边缘的焊接方面存在的问题。 相似文献
79.
This paper presents an efficient method which provides the optimal generation mix and the optimal generation construction process. The approximation method in which the dynamic programming technique and gradient method are combined is applied to determine the optimal generation mix with hydropower generation technologies. The successive approximations dynamic programming (SADP) technique, which is very suitable for high-dimensional multistage decision process problems, is used for obtaining the optimal generation construction process. The effectiveness and feasibility of the developed technique are demonstrated on a practical power system model which has five types of generation technologies including a hydropower generation technology. 相似文献
80.
What has become known as Community Operational Research has been around in the UK for many years. The election of Jonathan Rosenhead as President of the UK OR Society in 1986–87 was the catalyst for bringing together and expanding activities which had been carried out largely by individuals working in isolation on a voluntary basis. The following five years have seen the establishment of the Community OR Unit at Northern College, the Centre for Community OR at Hull University and the Community OR Network, which supports the activities of volunteer OR workers across the UK. This paper reviews the range and types of work which have been undertaken by various practitioners. An assessment of the success of community OR is made and a number of issues which have arisen are discussed. Finally, given the diverse nature of community OR, its practice and practitioners, there is some discussion about the future of the area. 相似文献