全文获取类型
收费全文 | 26311篇 |
免费 | 2215篇 |
国内免费 | 1593篇 |
专业分类
电工技术 | 1479篇 |
技术理论 | 1篇 |
综合类 | 1332篇 |
化学工业 | 2139篇 |
金属工艺 | 636篇 |
机械仪表 | 1420篇 |
建筑科学 | 1983篇 |
矿业工程 | 475篇 |
能源动力 | 5139篇 |
轻工业 | 393篇 |
水利工程 | 130篇 |
石油天然气 | 619篇 |
武器工业 | 249篇 |
无线电 | 3683篇 |
一般工业技术 | 1963篇 |
冶金工业 | 764篇 |
原子能技术 | 453篇 |
自动化技术 | 7261篇 |
出版年
2024年 | 98篇 |
2023年 | 444篇 |
2022年 | 780篇 |
2021年 | 893篇 |
2020年 | 829篇 |
2019年 | 764篇 |
2018年 | 739篇 |
2017年 | 876篇 |
2016年 | 1069篇 |
2015年 | 1109篇 |
2014年 | 1664篇 |
2013年 | 1581篇 |
2012年 | 1655篇 |
2011年 | 2594篇 |
2010年 | 2017篇 |
2009年 | 1815篇 |
2008年 | 1675篇 |
2007年 | 1739篇 |
2006年 | 1350篇 |
2005年 | 1045篇 |
2004年 | 797篇 |
2003年 | 755篇 |
2002年 | 554篇 |
2001年 | 444篇 |
2000年 | 381篇 |
1999年 | 337篇 |
1998年 | 321篇 |
1997年 | 253篇 |
1996年 | 222篇 |
1995年 | 186篇 |
1994年 | 176篇 |
1993年 | 129篇 |
1992年 | 105篇 |
1991年 | 84篇 |
1990年 | 83篇 |
1989年 | 67篇 |
1988年 | 54篇 |
1987年 | 38篇 |
1986年 | 34篇 |
1985年 | 78篇 |
1984年 | 68篇 |
1983年 | 59篇 |
1982年 | 62篇 |
1981年 | 22篇 |
1980年 | 23篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
《Drying Technology》2007,25(1):75-84
This article proposes a multiscale computational model able to calculate energy consumption in a batch lumber kiln. A dual-scale computational model of wood drying deals with the boards/stack interaction and serves as a basis for the present work. A new module was added here that calculates heat losses through kiln walls (convection, condensation) and the energy used by each kiln component (fans, heating elements, humidifier, vacuum pump, etc.). The corresponding mathematical formulation is presented and then theoretical results are compared to those collected in an industrial vacuum kiln. As application example, the effect of air reversal, air velocity, and kiln insulation are exhibited, which depicts the great potential and prospects of this new tool for energy savings in relation to the product quality. 相似文献
43.
G. Anandalingam 《Energy Policy》1985,13(4):335-339
This paper begins by examining the most energy-intensive industries and methods by which fuel efficiency can be improved. Next the author analyses the economics of energy conservation using specific case studies drawn from India. It is shown that investing in energy efficiency is more economical Btu per Btu than investing in the enhancement of domestic energy resources. The author also assesses changes in the economics of conservation for private firms when there are government incentives. Finally government policies that can overcome economic and non-economic disincentives for investing in energy conservation are examined. 相似文献
44.
45.
46.
47.
本文运用“软科学”一即通过建立数学模型,进行系统分析和系统优化,阐述对蒸汽管网优化运行的方法及原理,达到提高供热效率及节能降耗的目的. 相似文献
48.
T.‐S. Kang B.S. Harrison M. Bouguettaya T.J. Foley J.M. Boncella K.S. Schanze J.R. Reynolds 《Advanced functional materials》2003,13(3):205-210
Near‐infrared‐emitting electroluminescent (EL) devices using blue‐light‐emitting polymers blended with the Yb complexes Yb(DBM)3phen (DBM = dibenzoylmethane), Yb(DNM)3phen (DNM = dinaphthoylmethane), and Yb(TPP)L(OEt) (L(OEt) = [(C5H5)Co{P(O)Et2}3]–) have been studied. EL devices composed of Yb(DNM)3phen blended with PPP‐OR11 showed enhanced near‐IR output at 977 nm when compared to those fabricated with Yb(DBM)3phen/PPP‐OR11 blends. The maximum near‐IR external efficiencies of the devices with Yb(DBM)3phen and Yb(DNM)3phen are, respectively, 7 × 10–5 (at 6 V and at 0.81 mA mm–2) and 4 × 10–4 (at 7 V, and 0.74 mA mm–2). The optimal blend composition for EL device performance consisted of PPP‐OR11 blended with 10–20 mol‐% Yb(DNM)3phen. A device fabricated using Yb‐(TPP)L(OEt)/PPP‐OR11 showed significantly enhanced near‐IR output efficiency, and future efforts will focus on devices fabricated using porphyrin‐based materials. 相似文献
49.
Renewable energies are considered as an essential element of any strategy for sustainable energy development. The poor in the developing world without access to modern energies are regarded as a major market for renewable energies. This short paper attempts to analyse whether such a niche is backed by any economic logic and whether renewable energy and the poor nexus could be a strategy for success. The paper suggests that contrary to the common belief, the economic logic behind the niche is unsound and that the nexus is not a recipe for success. 相似文献
50.
卢金生 《理化检验(物理分册)》1995,31(6):27-30
通过对“软-软”、“中-软”、“中-中”、“中-硬”四组不同硬度匹配的滚子接触疲劳试验得出四条P-N曲线。并发现中硬度材料的接触疲劳寿命高于软材料,而当主试样为中硬时,与之相匹配的陪试件硬度越高,主试样的寿命越短,通过分析讨论解释了产生上述现象的原因及其失效机理。 相似文献