全文获取类型
收费全文 | 468082篇 |
免费 | 50581篇 |
国内免费 | 33637篇 |
专业分类
电工技术 | 38230篇 |
技术理论 | 11篇 |
综合类 | 45662篇 |
化学工业 | 61707篇 |
金属工艺 | 29927篇 |
机械仪表 | 31392篇 |
建筑科学 | 36120篇 |
矿业工程 | 16713篇 |
能源动力 | 12225篇 |
轻工业 | 48460篇 |
水利工程 | 14230篇 |
石油天然气 | 18225篇 |
武器工业 | 5782篇 |
无线电 | 52195篇 |
一般工业技术 | 44886篇 |
冶金工业 | 19786篇 |
原子能技术 | 7106篇 |
自动化技术 | 69643篇 |
出版年
2024年 | 2698篇 |
2023年 | 7594篇 |
2022年 | 16977篇 |
2021年 | 21925篇 |
2020年 | 16036篇 |
2019年 | 11636篇 |
2018年 | 12338篇 |
2017年 | 14564篇 |
2016年 | 12880篇 |
2015年 | 20009篇 |
2014年 | 25360篇 |
2013年 | 30304篇 |
2012年 | 36409篇 |
2011年 | 38993篇 |
2010年 | 36507篇 |
2009年 | 34529篇 |
2008年 | 35588篇 |
2007年 | 34307篇 |
2006年 | 30727篇 |
2005年 | 24988篇 |
2004年 | 17705篇 |
2003年 | 12831篇 |
2002年 | 12239篇 |
2001年 | 10860篇 |
2000年 | 9164篇 |
1999年 | 5483篇 |
1998年 | 3612篇 |
1997年 | 2884篇 |
1996年 | 2565篇 |
1995年 | 2081篇 |
1994年 | 1627篇 |
1993年 | 1313篇 |
1992年 | 1085篇 |
1991年 | 824篇 |
1990年 | 652篇 |
1989年 | 569篇 |
1988年 | 432篇 |
1987年 | 317篇 |
1986年 | 269篇 |
1985年 | 196篇 |
1984年 | 154篇 |
1983年 | 141篇 |
1982年 | 127篇 |
1981年 | 122篇 |
1980年 | 167篇 |
1979年 | 99篇 |
1977年 | 34篇 |
1976年 | 58篇 |
1959年 | 75篇 |
1951年 | 70篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
阐述了我国钢管行业进入"新常态"时期面临的主要问题,以及钢管企业经营状态;提出我国钢管企业提高生存能力的方向与开发新领域。建议我国钢管企业主动适应"新常态",及时转型,走差异化发展之路;找准生产产品的发展方向和路径;积极开发新领域,研发新产品。 相似文献
2.
3.
彭国强 《常州信息职业技术学院学报》2015,14(2)
现行的高职体育教学多是沿用普通高等学校的课程体系,课程内容并未反映高职教育应有的教育特点,没有很好地发挥体育教学与职业教育相衔接的教学效果.通过职业能力导向下高职实用性体育课程的实施,可以很好地培养学生未来工作岗位所需要的职业体能,提高职业身体素质,从而更好地服务高职教育的发展. 相似文献
4.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii 下载免费PDF全文
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献
5.
利用滑动式切比雪夫多项式拟合卫星坐标,详细介绍滑动式切比雪夫多项式拟合原理,并通过实例对比分析普通的切比雪夫多项式和滑动式切比雪夫多项式拟合卫星坐标的精度。结果表明,滑动式切比雪夫多项式拟合卫星坐标的精度比普通的切比雪夫多项式拟合精度高,在插值端点处能够很好地克服振荡和跳跃现象。 相似文献
6.
Yuanyuan Zhang Haiyan Lu Bing Wang Zhuo Zhang Xiaorong Lin Zhongzheng Chen Bin Li 《International Journal of Food Science & Technology》2015,50(6):1397-1404
Removal of imidacloprid and acetamiprid in tea infusions by microfiltration membrane using dead‐end model was investigated in the present study. The results showed that microfiltration significantly promoted the removal of both pesticides (P < 0.05) in tea infusions. Furthermore, the extent of removal was strongly influenced by the pore size of membrane, operational pressure and the concentrations of tea infusions. The initial concentration of imidacloprid and acetamiprid showed no significant effect on their removal rates. The maximum removal rates were 79.7% for imidacloprid and 81.9% acetamiprid. The changes in major chemical components of tea infusions after microfiltration were evaluated. The results indicated that microfiltration caused no considerable changes in total polyphenols and total free amino acids, and small but statistically significant losses (6.3–18.0%) of eight catechins and three methylxanthines when filtration volume reached to 200 mL. The present study validated the application of microfiltration as a potentially feasible and promising method for the removal of imidacloprid and acetamiprid residues from tea infusions. 相似文献
7.
针对基站柜式空调耗电量大的问题,创造性地使用基站分布式冷却的方式,达到精确送风,节能高效的目的.在应用实践中检验了分布式冷却系统实际节能量和应用效果,总结出分布式冷却系统应用场景和范围,为更大范围推广应用DCS分布式冷却系统提供实践依据. 相似文献
8.
9.
Rectangular section control technology(RSCT)was introduced to achieve high-precision profile control during silicon steel rolling.The RSCT principle and method were designed,and the whole RSCT control strategy was developed.Specifically,RSCT included roll contour design,rolling technology optimization,and control strategy development,aiming at both hot strip mills(HSMs)and cold strip mills(CSMs).Firstly,through the high-performance variable crown(HVC)work roll optimization design in the upper-stream stands and the limited shifting technology for schedule-free rolling in the downstream stands of HSMs,a hot strip with a stable crown and limited wedge,local spot,and single wave was obtained,which was suitable for cold rolling.Secondly,an approximately rectangular section was obtained by edge varying contact(EVC)work roll contour design,edge-drop setting control,and closed loop control in the upper-stream stands of CSMs.Moreover,complex-mode flatness control was realized by coordinating multiple shape-control methods in the downstream stands of CSMs.In addition,the RSCT approach was applied in several silicon-steel production plants,where an outstanding performance and remarkable economic benefits were observed. 相似文献
10.
为检查工程质量,查找输水系统可能存在的问题并消除隐患,保障电站安全运行,福建仙游抽水蓄能电站在投产发电前,要对输水发电系统进行充水试验与放空排水试验,在试验过程中监测输水系统的应力、应变与渗漏水情况。本文以尾水系统为例,介绍了试验所应具备的工程条件、工作程序及技术要求、试验成果分析和存在问题处理等。试验表明,仙游抽水蓄能电站尾水系统设计合理,施工质量优良,结构可靠,可供同类工程参考与借鉴。 相似文献