全文获取类型
收费全文 | 7656篇 |
免费 | 1023篇 |
国内免费 | 166篇 |
专业分类
电工技术 | 230篇 |
综合类 | 568篇 |
化学工业 | 1163篇 |
金属工艺 | 305篇 |
机械仪表 | 86篇 |
建筑科学 | 264篇 |
矿业工程 | 4115篇 |
能源动力 | 104篇 |
轻工业 | 218篇 |
水利工程 | 29篇 |
石油天然气 | 82篇 |
武器工业 | 8篇 |
无线电 | 71篇 |
一般工业技术 | 188篇 |
冶金工业 | 1155篇 |
原子能技术 | 24篇 |
自动化技术 | 235篇 |
出版年
2024年 | 29篇 |
2023年 | 80篇 |
2022年 | 197篇 |
2021年 | 313篇 |
2020年 | 304篇 |
2019年 | 228篇 |
2018年 | 279篇 |
2017年 | 298篇 |
2016年 | 386篇 |
2015年 | 374篇 |
2014年 | 525篇 |
2013年 | 531篇 |
2012年 | 671篇 |
2011年 | 635篇 |
2010年 | 362篇 |
2009年 | 382篇 |
2008年 | 320篇 |
2007年 | 350篇 |
2006年 | 336篇 |
2005年 | 267篇 |
2004年 | 265篇 |
2003年 | 233篇 |
2002年 | 201篇 |
2001年 | 166篇 |
2000年 | 181篇 |
1999年 | 140篇 |
1998年 | 119篇 |
1997年 | 223篇 |
1996年 | 86篇 |
1995年 | 76篇 |
1994年 | 75篇 |
1993年 | 48篇 |
1992年 | 53篇 |
1991年 | 23篇 |
1990年 | 27篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有8845条查询结果,搜索用时 15 毫秒
1.
段潇乐 《湖南工业职业技术学院学报》2015,(1):82-84
本研究检测了直接和间接两种修正性反馈与国内高职理科学生写作水平的关系。本实验持续五周,将150名学习者分为直接反馈组、间接反馈组及控制组,共安排了一次预先测试,,一次即时后测和一次延时后测,并分别对各组进行考察,结果显示两个实验组进步显著,且直接反馈效果最明显。 相似文献
2.
Flotation has been used in industry for more than a half century as the primary technique for upgrading phosphate. While the flotation of phosphate was inefficient when oleic acid was used alone as a collector, therefore a mixed collector of oleic acid (HOl), linoleic acid (LA) and linolenic acid (LNA) was employed to improve the recovery of phosphate flotation. The batch flotation results showed that the optimal composition of the mixed collector was 54 wt.% HOl, 36 wt.% LA and 10 wt.% LNA. Additionally, the effect of pH on the mixed collector application was studied while considering the surface tension, contact angle and micro-flotation. The results showed that the mixed collector should be used at a pH of 9.5. Above a pH of 9.5, the adsorption of fatty acids dimers on the apatite surface hindered phosphate flotation. The influence of the mixed collector assembly on apatite flotation was also investigated. It was demonstrated that due to its low critical micelle concentration, a sufficiently hydrophobic apatite surface could be generated at a collector concentration of 60 mg/L. In addition, zeta potential experiments suggested that collector adsorption was governed by chemisorption. FTIR and XPS spectra studies further indicated that the chemical reaction involved the carboxyl groups of fatty acids and Ca species at the apatite surface for each fatty acid in the mixed collector. 相似文献
3.
It is the aim of this paper to examine the effects of conditioning time on the flotation of hematite using three technical grade fatty acid reagents as providing additional evidence on their mechanism of interaction with the hematite surface. Various mechanisms have been postulated as occurring as conditioning time is increased. Both physical (e.g. conditioning time and power input) and chemical (nature, dispersion and solubility of the adsorbing species) contribute to the mechanisms of attachment of collector. In this paper, the mechanism of attachment of oleate to hematite can be readily explained by chemisorption, but the mechanism of attachment of lauric acid appears to be physical adsorption at neutral pH. The flotation of hematite with a mixture of tallow-type fatty acids (palmitic, stearic and oleic acids) is very sensitive to conditioning time, and suggests that, even though flotation is very effective at short conditioning times, it is very susceptible to the presence of fines and their associated high surface areas. It is therefore obvious that both the physical and chemical conditions contribute to the mechanisms of adsorption of fatty acids on iron-containing oxide minerals and must be understood in order to optimise the flotation of these minerals in an industrial situation. 相似文献
4.
白钨矿浮选731捕收剂低温乳化试验研究 总被引:2,自引:1,他引:1
介绍了731捕收剂在低温条件下试验的情况。试验研究结果表明,采用A和B药剂以5:6的比例混合组成的复合乳化剂对731进行乳化,低温时乳化体系稳定性好,浮选过程中降低乳化731的用量,同时提高了选择性,降低了浮选成本,实现了低温环境下白钨矿正常浮选作业,达到选矿技术攻关指标。 相似文献
5.
某铅锌矿选矿尾矿综合利用试验研究 总被引:2,自引:0,他引:2
针对选矿尾矿的特性,采用高选择性的3ACH捕收剂、F—1抑制剂,回收了绢云母含量分别达96%和64%以上的一、二级绢云母产品。经应用试验表明:绢云母一级品在橡胶中的补强性能基本达到了沉淀法白炭黑水平,二级品也全面超过硅铝炭黑的补强性能。 相似文献
6.
The ability to accurately and reliably predict whether an older adult will commit suicide has eluded clinicians and researchers. A random national sample of psychologists who work with older adults was surveyed regarding their perception of 36 risk factors for completed suicide and indirect self-destructive behavior in older adults. This study produced a profile of psychologists' assessment and treatment practices when working with suicidal older adults. Determining what psychologists consider to be the most salient risk factors for completed suicide is important in identifying a minimum standard that clinicians should follow when assessing older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
8.
金属-橡胶硫化粘接过程中分子取向行为的间接证据 总被引:2,自引:1,他引:1
对金属-橡胶热硫化粘接复合体的剥离行为进行了研究,同一粘接试样的双向180°剥离试验显示出了巨大的差异。本文分析了弹性材料在硫化过程中的分子行为,并提出了相应的新假设,认为这是由于金属-橡胶在硫化粘接过程中分子取向交联行为所致。这种双向180°剥离破坏现象可被看作是金属-橡胶硫化粘接过程中分子取向行为的间接证据。 相似文献
9.
10.