全文获取类型
收费全文 | 29142篇 |
免费 | 2427篇 |
国内免费 | 1457篇 |
专业分类
电工技术 | 5430篇 |
技术理论 | 3篇 |
综合类 | 2982篇 |
化学工业 | 4736篇 |
金属工艺 | 916篇 |
机械仪表 | 1006篇 |
建筑科学 | 3126篇 |
矿业工程 | 821篇 |
能源动力 | 1539篇 |
轻工业 | 1391篇 |
水利工程 | 1309篇 |
石油天然气 | 1645篇 |
武器工业 | 106篇 |
无线电 | 1348篇 |
一般工业技术 | 2154篇 |
冶金工业 | 1503篇 |
原子能技术 | 73篇 |
自动化技术 | 2938篇 |
出版年
2024年 | 117篇 |
2023年 | 355篇 |
2022年 | 633篇 |
2021年 | 786篇 |
2020年 | 884篇 |
2019年 | 769篇 |
2018年 | 656篇 |
2017年 | 810篇 |
2016年 | 914篇 |
2015年 | 868篇 |
2014年 | 1596篇 |
2013年 | 1440篇 |
2012年 | 1682篇 |
2011年 | 1899篇 |
2010年 | 1476篇 |
2009年 | 1819篇 |
2008年 | 1561篇 |
2007年 | 2194篇 |
2006年 | 2055篇 |
2005年 | 1707篇 |
2004年 | 1589篇 |
2003年 | 1526篇 |
2002年 | 1198篇 |
2001年 | 1020篇 |
2000年 | 815篇 |
1999年 | 601篇 |
1998年 | 453篇 |
1997年 | 340篇 |
1996年 | 248篇 |
1995年 | 227篇 |
1994年 | 168篇 |
1993年 | 102篇 |
1992年 | 70篇 |
1991年 | 53篇 |
1990年 | 45篇 |
1989年 | 38篇 |
1988年 | 19篇 |
1987年 | 20篇 |
1986年 | 19篇 |
1985年 | 33篇 |
1984年 | 22篇 |
1983年 | 22篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 15篇 |
1979年 | 16篇 |
1978年 | 8篇 |
1964年 | 13篇 |
1957年 | 11篇 |
1956年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
101.
Scale and sludge from Bulalo geothermal field, Philippines, have been characterized by whole rock analysis, radioactivity counting, size analysis, light microscopy, scanning electron microscopy, and X-ray diffraction. Their leachability was assessed by regulatory leaching procedures and by sequential extraction. Both scale and sludge consisted mostly of oxides of Si, Al, and Fe with no radionuclides detected. The scale had 10% S content. Sulfides and silicates were important phases in both samples having size ranges from submicron to 2 mm. Geothermal soils at Bulalo have higher than normal soil levels of As, S, Cu, Cr, Zn, and Pb but regulatory leaching tests indicated that these elements are not released. However, the sequential extraction showed that As, Cu, and Zn were leachable under extreme conditions. 相似文献
102.
本文提出了一个圆片规模布局算法,它是国外一个相应算法的改进形式,区别在于利用力定向布局法的方式不同。在相对位置阶段,该算法利用布局的层次特性将需确定所有电路元件相对位置的问题缩减至仅需确定宏电路元件相对位置的问题;在实际位置阶段,采用分治策略和取消前阶段层次划分的方式回避了需确定任意元实际位置的问题.其时间复杂度远低于国外相应算法. 相似文献
103.
A response to criticism of threshold plates for the study of color vision developed at the Mendeleev All-Russia Research Institute
of Metrology and published in 1994 is presented. The critics base their conclusions on colorimetric testing and the examination
of the plates.
In response to the article by M. V. Danilova and J. D. Mollon [4].
__________
Translated from Izmeritel’naya Tekhnika, No. 1, pp. 37–39, January, 2007. 相似文献
104.
105.
能否适应市场需求、得到社会认可是衡量高等技术应用型人才的唯一标准。本文提出要确立以市场需求为导向的人才培养观念,适应行业和地方经济的发展需要进行高职高专院校的专业建设和课程改革,并加强校企合作,突出校外实习在高职高专人才培养中的重要地位。 相似文献
106.
Richard D. Prosser 《Energy Economics》1985,7(1):9-12
Four models with different lag structures are used to express final energy demand in OECD from 1960–1982 as a function of real GDP and average energy price. The income and long-run price elasticities are not significantly dependent on the model specification, but the Koyck lag scheme, estimated in its distributed lag form, is found to give the most satisfactory results. The statistical properties of the data together with evidence of trends in the elasticities both suggest that the period of falling real prices prior to 1971 is not comparable to the present period. For the period after 1971, an income elsticity of 1.02 and a long-run price elasticity of -0.37 are obtained. 相似文献
107.
介绍了XC型车号自动识别系统的工作原理及在轨道衡的应用,解决了长期以来轨道衡路用车车号和自重依靠人工抄录易出错及劳动强度大的问题。 相似文献
108.
From the results reported here it is suggested that policy decisions about the potential contribution of decentralized energy supply systems to UK industrial energy requirements should be based on the suitability of individual sectors rather than averaged over all sectors. The suitability of decentralized energy sources is evaluated, based on a themodynamic match between source and demand. This suitability criterion is used to identify the most appropriate sector in manufacturing industries for the adoption of decentralized energy supply, leaving aside economic cost considerations and individual site requirements. 相似文献
109.
中部地区水资源总量为39.61亿m3。城市用水与农业、生态用水矛盾突出,城市供水能力不足,水污染问题严重,地下水超采严重,水资源开发利用不协调。该区水资源已无进一步开发利用的潜力,需通过调水工程解决缺水问题。水资源配置思路为从地处松花江上游的丰满水库引水,增加供水能力。 相似文献
110.
A method was developed to assess the heat insulation performance of intumescent coatings. The method consists of temperature measurements using the bench‐scaled experimental set‐up of a cone calorimeter and finite difference simulation to calculate the effective thermal conductivity dependent on time/temperature. This simulation procedure was also adapted to the small scale test furnace, in which the standard time–temperature curve is applied to a larger sample and thus which provides results relevant for approval. Investigations on temperature and calculated effective thermal conduction were performed on intumescent coatings in both experimental set‐ups using various coating thicknesses. The results correspond to each other as well as showing the limits of transferability between both fire tests. It is shown that bench‐scaled cone calorimeter tests are a valuable tool for assessing and predicting the performance of intumescent coatings in larger tests relevant for approval. The correlation fails for processes at surface temperatures above 750°C, which are not reached in the cone calorimeter, but are attained in the small scale furnace set‐up. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献