全文获取类型
收费全文 | 22554篇 |
免费 | 2830篇 |
国内免费 | 1788篇 |
专业分类
电工技术 | 4184篇 |
综合类 | 2867篇 |
化学工业 | 1095篇 |
金属工艺 | 328篇 |
机械仪表 | 1502篇 |
建筑科学 | 2582篇 |
矿业工程 | 724篇 |
能源动力 | 924篇 |
轻工业 | 390篇 |
水利工程 | 1726篇 |
石油天然气 | 553篇 |
武器工业 | 349篇 |
无线电 | 1847篇 |
一般工业技术 | 1526篇 |
冶金工业 | 394篇 |
原子能技术 | 112篇 |
自动化技术 | 6069篇 |
出版年
2024年 | 122篇 |
2023年 | 291篇 |
2022年 | 522篇 |
2021年 | 634篇 |
2020年 | 796篇 |
2019年 | 661篇 |
2018年 | 651篇 |
2017年 | 838篇 |
2016年 | 856篇 |
2015年 | 926篇 |
2014年 | 1562篇 |
2013年 | 1411篇 |
2012年 | 1840篇 |
2011年 | 1781篇 |
2010年 | 1302篇 |
2009年 | 1403篇 |
2008年 | 1372篇 |
2007年 | 1674篇 |
2006年 | 1350篇 |
2005年 | 1130篇 |
2004年 | 979篇 |
2003年 | 867篇 |
2002年 | 677篇 |
2001年 | 584篇 |
2000年 | 516篇 |
1999年 | 401篇 |
1998年 | 282篇 |
1997年 | 285篇 |
1996年 | 245篇 |
1995年 | 200篇 |
1994年 | 167篇 |
1993年 | 126篇 |
1992年 | 131篇 |
1991年 | 103篇 |
1990年 | 98篇 |
1989年 | 82篇 |
1988年 | 65篇 |
1987年 | 28篇 |
1986年 | 14篇 |
1985年 | 17篇 |
1984年 | 27篇 |
1983年 | 15篇 |
1982年 | 24篇 |
1981年 | 23篇 |
1980年 | 22篇 |
1979年 | 27篇 |
1978年 | 14篇 |
1977年 | 14篇 |
1959年 | 3篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
972.
973.
This study introduces WRF-LTNGDA, a lightning data assimilation technique implemented in the Weather Research and Forecasting (WRF) model. This technique employs lightning for improving the representation of convection by means of controlling the triggering of the model's convection parameterization scheme. The development and implementation of WRF-LTNGDA was carried out in a framework that could easily allow for its exploitation in real-time forecasting activities. The assimilation algorithm was evaluated over eight precipitation events that took place in Greece in the years 2010–2013. Results clearly show that lightning forcing has a positive impact on model performance. The conducted analysis revealed that the employment of WRF-LTNGDA induces statistically significant improvements in precipitation verification scores, especially for high rainfall accumulations. Separate examination of one of the eight case studies highlighted the overall better agreement between the modelled and observed spatial distribution of precipitation when lightning data assimilation was applied, than in the control simulation. 相似文献
974.
975.
江苏沿海滩涂开发优化的动力机制研究 总被引:1,自引:0,他引:1
江苏沿海滩涂开发具有悠久的历史,但是传统的滩涂开发模式已经不能适应江苏省"强富美高"的发展新理念,现有的滩涂开发模式亟需优化升级。经过对由经济发展、生产方式变革、自然环境等要素构成的滩涂优化开发内源动力以及由科技创新、资金保障、政策制度等要素构成的外源动力进行分析,并对其连续动力机制进行深入研究,发现滩涂开发在其内外源动力的共同作用下可以逐步缓解人地矛盾,实现经济效益和富民的效应;但是开发与环境之间互为影响,甚至可能与环境美的目标相反。研究结果表明:在滩涂开发过程中,应坚持生态优先、绿色发展,加强政府引导、理顺机制,注重高新产业、科技投入,围绕临海能源、绿化造林,只有这样才能推动滩涂开发动力机制不断正向循环,实现经济社会的可持续发展。 相似文献
976.
《Journal of Nuclear Science and Technology》2013,50(6):584-586
Calculation of one of the SIMBATH experiments was performed using the SIMMER-II code. The experiments were intended to simulate the fuel pin disintegration, the molten materials relocation and following materials redistribution that could occur during core disruptive accidents assumed in fast breeder reactors. The calculation by SIMMER-II showed that the incorporated step-wise fuel pin disintegration model and the modified particle jamming model were capable of reproducing the course of materials relocation within the identified ranges of the parameters which governed the blockages formation, i.e. the characteristic radius of solid particles jamming and/or sieving out in the flow and the effective particle viscosity. In particular the final materials redistribution calculated by SIMMER-II very well reproduced the experiment. This fact made it possible to interpret theoretically the mechanisms of flow blockages formation and related materials redistribution. 相似文献
977.
978.
在某钢厂的轧机机架优化设计过程中采用有限元分析方法,模拟计算各个设计参数下的不同机架垂直刚度及机架的应力分布状况,得到最优的机架设计参数,节约了工程成本,保证了设备质量. 相似文献
979.
A Two‐Stage Stochastic Mixed‐Integer Programming Approach to the Smart House Scheduling Problem
下载免费PDF全文
![点击此处可从《Electrical Engineering in Japan》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A “smart house” is a highly energy‐optimized house equipped with photovoltaic (PV) systems, electric battery systems, fuel cell (FC) cogeneration systems, electric vehicles (EVs), and so on. Smart houses are attracting much attention recently because of their enhanced ability to save energy by making full use of renewable energy and by achieving power grid stability despite an increased power draw for installed PV systems. Yet running a smart house's power system, with its multiple power sources and power storages, is no simple task. In this paper, we consider the problem of power scheduling for a smart house with a PV system, an FC cogeneration system, and an EV. We formulate the problem as a mixed‐integer programming problem, and then extend it to a stochastic programming problem involving recourse costs to cope with uncertain electricity demand, heat demand, and PV power generation. Using our method, we seek to achieve the optimal power schedule running at the minimum expected operation cost. We present some results of numerical experiments with data on real‐life demands and PV power generation to show the effectiveness of our method. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(4): 48–58, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22336 相似文献
980.
Recently, Hou et al. introduced a novel (2, n) privilege-based visual cryptography scheme (PVCS) with various privilege levels of shadow images. In this scheme, a shadow with a higher privilege contributes more recovered information, while a lower privileged shadow has the less recovery capability. Moreover, the visual quality of stacked result depends on the total sum of privilege levels for all involved shadows in reconstruction. Unfortunately, the PVC scheme has the inconsistency of the contrast of recovered image and the sum of privilege levels. Accordingly, an enhanced Hou et al.’s (2, n)-PVC scheme (EPVCS) is proposed to solve this inconsistency problem. However, the EPVCS is not a general solution to implement all PVCSs with arbitrary privilege levels, and it also has the unequal whiteness of shadows. In this paper, we first extend Hou et al.’s (2, n)-EPVCS with a correct privilege levels achieving the consistency of the contrast and the sum of privilege levels. Then we construct a (2, n)-PVCS to allow arbitrary privilege levels and provide the equal whiteness for each shadow. 相似文献