全文获取类型
收费全文 | 964篇 |
免费 | 105篇 |
国内免费 | 52篇 |
专业分类
电工技术 | 28篇 |
综合类 | 87篇 |
化学工业 | 120篇 |
金属工艺 | 5篇 |
机械仪表 | 2篇 |
建筑科学 | 27篇 |
矿业工程 | 22篇 |
能源动力 | 43篇 |
轻工业 | 242篇 |
水利工程 | 460篇 |
石油天然气 | 23篇 |
无线电 | 6篇 |
一般工业技术 | 16篇 |
冶金工业 | 22篇 |
原子能技术 | 4篇 |
自动化技术 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 24篇 |
2021年 | 16篇 |
2020年 | 37篇 |
2019年 | 25篇 |
2018年 | 21篇 |
2017年 | 30篇 |
2016年 | 28篇 |
2015年 | 25篇 |
2014年 | 71篇 |
2013年 | 58篇 |
2012年 | 82篇 |
2011年 | 82篇 |
2010年 | 31篇 |
2009年 | 39篇 |
2008年 | 55篇 |
2007年 | 52篇 |
2006年 | 77篇 |
2005年 | 60篇 |
2004年 | 43篇 |
2003年 | 44篇 |
2002年 | 49篇 |
2001年 | 19篇 |
2000年 | 24篇 |
1999年 | 17篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1985年 | 3篇 |
1983年 | 1篇 |
排序方式: 共有1121条查询结果,搜索用时 187 毫秒
1.
2.
3.
为解决纯棉针织物练漂温度高、能耗大等问题,研究自制低温练漂催化剂WXP-100对纯棉针织物练漂一浴前处理效果的影响。优化的低温练漂工艺条件为:催化剂WXP-100质量浓度为2 g/L,氢氧化钠质量浓度为2 g/L,多功能精练剂L质量浓度为6 g/L,30%双氧水体积分数为12 mL/L,70℃处理60 min。研究发现,催化剂WXP-100能够有效促进棉针织物练漂,70℃低温练漂织物的吸水性达到传统高温练漂效果,而且织物的顶破强力保留率高,纤维损伤明显减小,白度略低于传统练漂织物。 相似文献
4.
5.
Dams disrupt the flow of water and sediment and thus have the potential to affect the downstream geomorphic characteristics of a river. Though there are some well‐known and common geomorphic responses to dams, such as bed armouring, the response downstream from any particular dam is dependent on local conditions. Herein, we investigate the response of the upper Santa Ana River in southern California, USA, to the construction of a large dam at the transition from mountains to valley, using calculations of bedload transport capacity on the mainstem below the dam and for major tributaries. Approximate sediment budgets were constructed for downstream reaches to estimate deposition and erosion rates for sand, gravel, and cobble particle sizes. Our results indicate that the classical response of bed armouring and erosion is likely limited to a short reach immediately below the dam. Farther downstream, though transport capacity is reduced by flow regulation by the dam, the channel reaches are likely to remain depositional but with reduced deposition rates. Persistent deposition, as opposed to erosion, is the result of the replenishment of flow and sediment supply by large downstream tributaries. In addition, the calculations indicate that the composition of the bed is unlikely to change substantially in downstream reaches. A Monte Carlo approach was employed to estimate the uncertainty in the sediment budget predictions. The impacts of the dam on the geomorphic character of the river downstream could have implications for native fish that rely on coarse substrate that supports their food base. 相似文献
6.
7.
Treatment of strongflow wool scouring effluent by biological emulsion destabilisation 总被引:4,自引:0,他引:4
The stable oil-in-water emulsion contained in wool scouring effluent was destabilised by aerobic biological treatment as the basis of a potential new effluent treatment process. The de-emulsified wool wax, which is recalcitrant to biodegradation, can then be readily removed by centrifugation. In 12-day batch experiments, 97% of wool wax and 87% of COD were removed after gentle centrifuging at 200 x g, compared to only 6% and 8%, respectively, for sterile controls. Steady-state chemostat experiments under optimum conditions gave essentially complete removal of wool wax and 90% removal of COD at less than 40 h retention time, and demonstrated that the mechanism of pollutant removal was by bioflocculation rather than aerobic degradation. At 100 L pilot scale, 95% of wool wax and 82% of COD were consistently removed over a period of 116 days of continuous operation at 38 h retention time and 30 degrees C, producing a spadable sludge of 5.7 mL/g. Variable influent concentration or filamentous bacteria did not disrupt this process and foaming was readily controlled using a mechanical foam breaker. After a shutdown period of 15 days the process could be restarted easily, achieving normal performance within one retention time. The successful operation of the pilot reactor suggests this process could be developed to full scale and incorporated into an overall treatment package. 相似文献
8.
Bioactive peptides and carbohydrates are sourced from a myriad of plant, animal and insects and have huge potential for use as food ingredients and pharmaceuticals. However, downstream processing bottlenecks hinder the potential use of these natural bioactive compounds and add cost to production processes. This review discusses the health benefits and bioactivities associated with peptides and carbohydrates of natural origin and downstream processing methodologies and novel processes which may be used to overcome these. 相似文献
9.
近海风机大直径单桩在波浪的作用下承受水平循环荷载,并产生冲刷效应。采用一套可施加大周数循环荷载的试验装置,探究砂土中冲刷深度与加载路径耦合作用下大直径单桩累积变形特性与位移预测模型。通过对试验结果归一化和回归分析,得到位移预测模型,其为循环次数的幂指数和初次循环累计位移两者的乘积。研究发现,幂指数受加载路径和冲刷深度的影响较小;初次循环累积位移由两个相互独立的参数决定,即荷载峰值和控制循环幅值的荷载类型。荷载峰值受冲刷深度影响,荷载类型与冲刷深度无耦合关系。试验得到的位移预测模型的幂指数和初次循环累积位移公式可用于单桩长期水平循环累积位移的预测。 相似文献
10.
黄河下游河床存在典型的分层结构,不同部位对水流抗冲性不同,抗冲性极强的"胶泥层"对河势演变具有重大影响。通过对黄河下游花园口附近黏性土进行取样,开展了黄河下游河岸黏性土起动冲刷的水槽试验。分析了起动切应力随干密度的变化情况,建立了干密度、含水率与淤积历时的关系,拟合了黏性土侵蚀系数与起动切应力的关系式,结果表明:黏性土起动切应力随干密度的增大而增大,两者呈幂函数关系;当淤积历时较短时,黏性土干密度(含水率)随淤积历时的增大而增大(减小),两者呈对数函数(指数函数)关系;黏性土侵蚀系数随起动切应力的增大而减小,两者呈幂函数关系;同时研究发现,黏性土起动切应力与黏粒含量相关,相同干密度条件下,黏粒含量越高起动切应力越大;黏性土侵蚀系数与该土体的黏粒含量、土体结构相关,黏粒含量越高侵蚀系数越小,相应的其抗冲性越强。 相似文献