全文获取类型
收费全文 | 352篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 21篇 |
综合类 | 22篇 |
化学工业 | 70篇 |
金属工艺 | 5篇 |
机械仪表 | 24篇 |
建筑科学 | 29篇 |
矿业工程 | 13篇 |
能源动力 | 22篇 |
轻工业 | 29篇 |
水利工程 | 6篇 |
石油天然气 | 32篇 |
武器工业 | 2篇 |
无线电 | 8篇 |
一般工业技术 | 22篇 |
冶金工业 | 26篇 |
原子能技术 | 8篇 |
自动化技术 | 21篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 15篇 |
2014年 | 20篇 |
2013年 | 13篇 |
2012年 | 10篇 |
2011年 | 29篇 |
2010年 | 23篇 |
2009年 | 16篇 |
2008年 | 17篇 |
2007年 | 12篇 |
2006年 | 30篇 |
2005年 | 19篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 11篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有360条查询结果,搜索用时 15 毫秒
1.
通过分析A公司在研发项目范围管理中所存在问题,提出研发项目范围管理的方法及其在C产品的应用实例,通过运用研发项目范围管理的工具和方法,改善产品开发流程,从而缩短新产品开发周期,提高响应市场的速度,并提高企业研发项目的管理能力。 相似文献
2.
以循环内皮细胞(CEC)作为血管内皮细胞(VEC)损伤的指示物,以血浆内皮素(ET)和前列环素(PGI2)反映VEC的功能变化,对85例冠心病患者与30例正常人进行对比研究,并对50例不稳定型心绞痛及20例急性心肌梗塞进行了动态观察.结果表明:冠心病外周血中CEC、ET明显升高(P<0.001),PGI2明显下降(P<0.001),尤以不稳定型心绞痛和急性心肌梗塞更显著,与病情的严重程度相一致.提示冠心病VEC损伤,以及它所分泌的内皮源性舒缩因子失平衡参与了冠心病的病理过程。 相似文献
3.
攀枝花矿产资源特征及循环经济发展策略探讨 总被引:2,自引:0,他引:2
文章着重描述了攀枝花矿产资源特征、资源矿物流向和资源产品定位,分析了资源矿物使用行业的不同特点,明确了针对攀枝花矿产资源利用的循环经济目标,根据资源循环利用技术水平和资源循环开发现状,提出了攀枝花矿的循环经济发展策略. 相似文献
4.
5.
6.
根据乙醛氧化反应催化剂的循环使用机理对湘维醋酸装置催化剂循环使用周期短的原因进行了分析,找出了反应温度偏高、氧醛比偏大、醋酸锰循环使用流程不合理、用工业水溶解醋酸锰等四项原因,并提出了改进措施,实施后使湘维醋酸装置催化剂循环使用周期达到了国内先进水平。 相似文献
7.
Solid circulation characteristics in an internally circulating fluidized bed with orifice-type draft tube 总被引:1,自引:0,他引:1
Sang Done Kim Yo Han Kim Seon Ah Roh Dong Hyun Lee 《Korean Journal of Chemical Engineering》2002,19(5):911-916
Effects of superficial gas velocities to a draft tube, to an annulus section and particle size on the solid circulation rate
(G,) have been determined in an internally circulating fluidized bed (0.28 m I.D. × 2m high) with an orifice type draft tube.
The solid circulation rate from the draft tube to an annulus section increases with increasing gas velocities to the draft
tube(U
d
) and annulus section (Ua) and consequent increase in pressure drop across the orifice (ΔPor). However, the values ofG
s
decrease by 7–21% with increasing particle size from 86 to 288 μm. The pressure drop across the orifice increases with increasingU
d
andU
a
. However, ΔPor decreases by 5–23% with increasing particle size. To predictG
s
in an internally circulating fluidized bed, a correlation is proposed as a function of ΔPor
This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement Korea University. 相似文献
8.
We present a new scaling algorithm for the maximum mean cut problem. The mean of a cut is defined by the cut capacity divided by the number of arcs crossing the cut. The algorithm uses an approximate binary search and solves the circulation feasibility problem with relaxed capacity bounds. The maximum mean cut problem has recently been studied as a dual analogue of the minimum mean cycle problem in the framework of the minimum cost flow problem by Ervolina and McCormick. A networkN=(G, lower, upper) with lower and upper arc capacities is said to be -feasible ifN has a feasible circulation when we relax the capacity bounds by ; that is, we use (lower(a)- , upper(a)+) bounds instead of (lower(a), upper(a)) bounds for each arca A. During an approximate binary search we maintain two bounds,LB andUB, such thatN is LB-infeasible andUB-feasible, and we reduce the interval size (LB, UB) by at least one-third at each iteration. For a graph withn vertices, m arcs, and integer capacities bounded byU, the running time of this algorithm is O(mn log(nU). This time bound is better than the time achieved by McCormick and Ervolina under thesimilarity condition (that is,U=O(no(1))). Our algorithm can be naturally used for the circulation feasibility problem, and thus provides a new scaling algorithm for the minimum cut problem.Research supported by a grant-in-aid of the Ministry of Education, Science and Culture of Japan. 相似文献
9.
《Advanced Powder Technology》2023,34(7):104050
The cylindrical hydrocyclone has been increasingly used in coarse classification due to its reduced fine particle entrainment, but the loss of coarse particles to overflow remains an intractable problem. Based on the notion that the strong circulation flow caused by the flat bottom structure bears primary responsibility for the problem, this study designs eight unique bottom profiles to regulate the particle circulating flow and attempts to correlate particle circulation flow with classification performance. The effects of the bottom profile on flow field characteristics, particle spatial distribution, circulation flow rates, and grade efficiency are explored in detail using validated models in a Φ200 mm cylindrical hydrocyclone. The findings suggest that bottom profiles have the greatest effect on the axial velocity near the bottom and the grade efficiency of intermediate and coarse particles, while all unique designs have the potential to lower turbulence intensity. An ascending segment near the wall or a descending segment near the axis can help to mitigate the misplacement of coarse particles by reducing particle circulation flow without affecting the entrainment of fines appreciably. Additionally, two circles are found on each side of the cut plane, which is conducive to releasing coarse particles from the circulation flow. Regulation of particle circulation flow by adjusting bottom profile parameters can improve separation performance. 相似文献
10.
结晶罐的循环比是否合理,反映了结晶罐结构性能的优劣。本文通过对糖膏在结晶罐中流动的压力降的分析,讨论了多降液管结晶罐的循环比的理论计算,并提出了等比例的校正方法,使整个计算过程变得非常简单。 相似文献