全文获取类型
收费全文 | 3960篇 |
免费 | 388篇 |
国内免费 | 185篇 |
专业分类
电工技术 | 18篇 |
综合类 | 148篇 |
化学工业 | 492篇 |
金属工艺 | 11篇 |
机械仪表 | 111篇 |
建筑科学 | 75篇 |
矿业工程 | 20篇 |
能源动力 | 13篇 |
轻工业 | 3255篇 |
水利工程 | 8篇 |
石油天然气 | 5篇 |
武器工业 | 1篇 |
无线电 | 51篇 |
一般工业技术 | 78篇 |
冶金工业 | 106篇 |
原子能技术 | 1篇 |
自动化技术 | 140篇 |
出版年
2024年 | 26篇 |
2023年 | 37篇 |
2022年 | 103篇 |
2021年 | 112篇 |
2020年 | 139篇 |
2019年 | 91篇 |
2018年 | 95篇 |
2017年 | 47篇 |
2016年 | 123篇 |
2015年 | 153篇 |
2014年 | 261篇 |
2013年 | 267篇 |
2012年 | 355篇 |
2011年 | 429篇 |
2010年 | 215篇 |
2009年 | 209篇 |
2008年 | 138篇 |
2007年 | 337篇 |
2006年 | 288篇 |
2005年 | 203篇 |
2004年 | 178篇 |
2003年 | 157篇 |
2002年 | 137篇 |
2001年 | 91篇 |
2000年 | 81篇 |
1999年 | 66篇 |
1998年 | 47篇 |
1997年 | 19篇 |
1996年 | 31篇 |
1995年 | 27篇 |
1994年 | 26篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有4533条查询结果,搜索用时 187 毫秒
91.
回溯算法在制丝生产线自动排产中的应用 总被引:1,自引:1,他引:0
烟草企业面临着市场供给和计划生产的双重挑战,烟草企业制丝生产线自动排产调度越来越受到重视,优化制丝生产调度是提高生产效率的重要手段.论文分析了烟草制丝自动排产的业务流程和质量指标,对制丝生产线的生产段、工艺柜等进行理论分析和科学建模,采用回溯算法实现了制造生产调度自动排产与优化,得到了预期效果. 相似文献
92.
Abstract The yellowish color of High Yield Pulp (HYP) gives some psychological obstacles and limits its application in some paper grades. Dyes are widely used in the papermaking process to shade the yellowish color of the paper products. We proposed to add dyes into the HYP manufacturing process to minimize the yellowish hue. In this work, we substituted the dye-added HYP (dyes added in the HYP manufacturing process) for hardwood kraft pulp in the production of fine paper grades, and compared the results from those by adding dyes into the papermaking wet end. A higher dye effectiveness was obtained when we used the dye-added HYP. Also, the dye-added HYP gave more effective performance of Precipitated Calcium Carbonate (PCC) fillers and Optical Brightening Agents (OBA) in terms of CIE whiteness and b*. In addition, the dye-added HYP showed less negative effect on brightness and better compatibility with other dyes. The underlying mechanism for the above experimental observation was proposed. 相似文献
93.
In order to identify the principal factors influencing soil water characteristics (SWC) and evaluate SWC effectively, the multivariate-statistical canonical correlation analysis (CCA) method was used to study and analyze the correlation between SWC and soil physical and chemical properties. Twenty-two soil samples were taken from 11 main tobacco-growing areas in Guizhou Province in China and the soil water characteristic curves (SWCC) and basic physical and chemical properties of the soil samples were determined. The results show that: (1) The soil bulk density, soil total porosity and soil capillary porosity have significant effects on SWC of tobacco fiels. Bulk density and total porosity are positively correlated with soil water retention characteristics (SWRC), and soil capillary porosity is positively correlated with soil water supply characteristics (SWSC). (2) Soil samples from different soil layers at the same soil sampling point show similarity or consistency in SWC. Inadequate soil water supply capability and imbalance between SWRC and SWSC are problems of tobacco soil. (3) The SWC of loamy clay are generally superior to those of silty clay loam. 相似文献
94.
主要研究了β21S钛合金的工艺塑性图,制定了该合金的锻造工艺参数。通过该合金的工艺塑性图,确定变形温度为750-1050℃,最大变形量为75%-80%,终缎温度为700℃。从合金的工艺塑性角度来看,以上 数据是合理的。 相似文献
95.
为开发质优价廉、环境友好的纸张表面施胶剂,用自制聚合物分散剂以苯乙烯、丙烯酸酯等为原料,不用有机溶剂合成了无皂产品(SSTOP)。IR、DSC分析表明,SSTOP是存在苯乙烯、丙烯酸酯等单体链节的共聚物。粒径分布和TEM分析表明,SSTOP微粒大小均一、呈核壳球状。在造纸厂的中试应用结果表明,在白纸板上,SSTOP与德国无皂产品BK-350效果相当,而每吨产品便宜700元。双胶纸上无皂型SSTOP与含乳化剂产品相比,处理纸张正、反面纸张表面吸水值分别降低10.2%、14.3%,表面强度提高20.8%和21.1%。 相似文献
96.
Borrelli Belinda; McQuaid Elizabeth L.; Novak Scott P.; Hammond S. Katharine; Becker Bruce 《Canadian Metallurgical Quarterly》2010,78(1):34
Objective: Secondhand smoke exposure is associated with asthma onset and exacerbation. Latino children have higher rates of asthma morbidity than other groups. The current study compared the effectiveness of a newly developed smoking cessation treatment with existing clinical guidelines for smoking cessation. Method: Latino caregivers who smoked (N = 133; 72.9% female; mean age = 36.8 years) and had a child with asthma were randomly assigned to receive 1 of 2 smoking cessation counseling interventions during a home-based asthma program: (a) behavioral action model (BAM; modeled on clinical guidelines for smoking cessation) or (b) precaution adoption model (PAM; feedback on the caregiver’s carbon monoxide level and child’s secondhand smoke exposure using Motivational Interviewing). Counseling was delivered by a bilingual Latina health educator, and the content was tailored to Latino values and culture. It was not necessary for smokers to want to quit smoking to participate. Smoking cessation was biochemically verified and secondhand smoke exposure was objectively measured through passive nicotine monitors. Results: Intent-to-treat analyses showed that 20.5% of participants in the PAM condition and 9.1% of those in the BAM condition were continuously abstinent at 2 months posttreatment (OR = 2.54; 95% CI = 0.91–7.10), whereas 19.1% of participants in the PAM condition and 12.3% of those in BAM condition were continuously abstinent at 3 months posttreatment (OR = 1.68; 95% CI = 0.64–4.37). Secondhand smoke exposure decreased only in the BAM condition (p p 相似文献
97.
98.
99.
造纸配料组分的湿部化学 总被引:1,自引:0,他引:1
对造纸配料组分及其胶体化学特性、表面动电行为、配料组分的聚集、吸附等作了较为系统的论述。 相似文献
100.
在蒸渗仪控制条件下就旺长期烤烟叶片细胞液质量分数的影响因子进行相关研究。结果表明:施氮量的增加对旺长期烤烟叶片蒸腾作用和光合作用的促进作用远大于对烤烟吸收水分的促进作用,在一定程度上提高了烤烟叶片细胞液质量分数;旺长期烤烟叶片细胞液质量分数随施氮量增加而增加,总施氮量超过67.5 kg/hm2时旺长期烤烟叶片细胞液质量分数减小;旺长期烤烟叶片细胞液质量分数与0~20 cm以及20~40 cm土层土壤含水率呈现负相关关系,与烟株水分蒸腾速率及烟株光合速率的负相关达到显著水平。 相似文献