全文获取类型
收费全文 | 190130篇 |
免费 | 16498篇 |
国内免费 | 9455篇 |
专业分类
电工技术 | 11652篇 |
技术理论 | 13篇 |
综合类 | 18536篇 |
化学工业 | 28564篇 |
金属工艺 | 8248篇 |
机械仪表 | 8123篇 |
建筑科学 | 33199篇 |
矿业工程 | 9082篇 |
能源动力 | 8214篇 |
轻工业 | 10518篇 |
水利工程 | 21031篇 |
石油天然气 | 12225篇 |
武器工业 | 1183篇 |
无线电 | 8453篇 |
一般工业技术 | 15644篇 |
冶金工业 | 7427篇 |
原子能技术 | 1818篇 |
自动化技术 | 12153篇 |
出版年
2024年 | 651篇 |
2023年 | 2392篇 |
2022年 | 4549篇 |
2021年 | 5285篇 |
2020年 | 5762篇 |
2019年 | 4546篇 |
2018年 | 4416篇 |
2017年 | 5498篇 |
2016年 | 6026篇 |
2015年 | 6264篇 |
2014年 | 11806篇 |
2013年 | 10990篇 |
2012年 | 13777篇 |
2011年 | 14340篇 |
2010年 | 10926篇 |
2009年 | 11586篇 |
2008年 | 10398篇 |
2007年 | 13070篇 |
2006年 | 12128篇 |
2005年 | 10708篇 |
2004年 | 8683篇 |
2003年 | 7792篇 |
2002年 | 6610篇 |
2001年 | 5436篇 |
2000年 | 4589篇 |
1999年 | 3629篇 |
1998年 | 2741篇 |
1997年 | 2266篇 |
1996年 | 1738篇 |
1995年 | 1536篇 |
1994年 | 1290篇 |
1993年 | 895篇 |
1992年 | 786篇 |
1991年 | 618篇 |
1990年 | 473篇 |
1989年 | 399篇 |
1988年 | 280篇 |
1987年 | 211篇 |
1986年 | 160篇 |
1985年 | 175篇 |
1984年 | 146篇 |
1983年 | 112篇 |
1982年 | 97篇 |
1981年 | 32篇 |
1980年 | 80篇 |
1979年 | 32篇 |
1978年 | 14篇 |
1976年 | 15篇 |
1975年 | 13篇 |
1951年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Wei-Cheng Tang Yi-Che Su Yun-Shan Huang Ya-Tin Yu Hsin-Lung Chen I-Ming Chu 《应用聚合物科学杂志》2019,136(39):48003
While perfluoroalkyl acids (PFAAs), also known as C8s, are used extensively in textile repellent coatings, concerns have arisen for their carcinogenicity and hazardous effects on the environment. In this study, a novel water-based, nonfluoro, and nanobrush textile repelling agent was prepared by conventional sol–gel chemistry using amorphous fumed silica and n-octyltriethoxysilane as the starting materials. Minimal interaction between the designed repelling agent and marketed water-based resins was confirmed using linear viscosity region (LVR) analysis and asymmetric-flow field-flow fractionation (AF4), suggesting the self-stratification potential of the repelling agent. More specifically, the repelling agent exhibited excellent compatibility and self-stratifying ability with a force-emulsified acrylic-based resin, affording a water contact angle of 104.3° when incorporated at 7% solid content. Performance tests carried out on thermoplastic polyurethane (TPU) revealed excellent adhesion (100/100) of a final formulation, and a significant increase in water contact angle from 80.1° to 103.8° after treatment. In addition, the fouling area after the removal of a submerged sample from a mixture of slurry, polymer, and oil decreased from 48 to 1% when the repelling agent was added. Moreover, the sludge-fouling property remained unchanged after 1000 cycles of abrasion. These findings demonstrate the potential of the described nonfluoro, nanobrush repelling agent as an environmentally safe alternative for use with commercial resins, in turn realizing a fully water-based hydrophobic coating. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48003. 相似文献
122.
Dujuan Li Wei Yan Ronghui Qi Li-Zhi Zhang 《International Journal of Hydrogen Energy》2021,46(14):9267-9279
PEM-based electrolytic air dehumidification is innovative in dehumidification that requires high precision and small space due to its high efficiency, compactness, and cleanness. However, the system dehumidification performance and durability are limited by using commercial Anatase-IrO2 catalysts. In this study, two types of structurally modified OER catalyst materials, ATO-IrO2 and ND-MnO2-IrO2, are developed to improve the performance of the system. System experiments showed that, compared to the commercial catalysts, the use of ATO-IrO2 and ND-MnO2-IrO2 as the anode catalyst can improve the dehumidification performance by 45% and 20%, respectively. Furthermore, in 50-h accelerated aging tests, the attenuation rates of the ATO-IrO2 and ND-MnO2-IrO2 systems are 3% and 8% respectively, which are far lower than the 35% attenuation of commercial catalyst. The results indicate that, as catalysts with a classic core-shell structure, ATO-IrO2 and ND-MnO2-IrO2 still have a significant impact on improving the performance of the electrolytic dehumidification systems. 相似文献
123.
This paper presents two well-instrumented large-scale field tests of PVD-improved soft soil with vacuum and surcharge preloading, respectively. The two large-scale field tests were conducted adjacent to each other with the same preload. A comparative analysis was performed to investigate the performance of subsoil (i.e., the ground settlement, the layered settlement, the lateral displacement of subsoil and pore water pressure) under vacuum preloading and equivalent surcharge preloading. Some design methods were verified based on the field data. Cone Penetration Tests (CPT) and Vane Shear Tests (VST) were conducted to assess the improvement effects on subsoil after preloading. The results showed that as compared with surcharge preloading, vacuum preloading mitigated the differential settlement of the ground. The vacuum pressure transmitted into the soil with a minor loss through the PVD length. From a practical point of view, the improvement effects by vacuum preloading and surcharge preloading were similar in terms of influence depth and soil strength based on the in-situ tests. 相似文献
124.
江苏油田的部分油井存在油管短路、地层高压低渗、漏失严重等问题,这些问题造成压井作业困难,并且压井作业过程中的井控与环境污染风险较大。为了进行不压井检泵作业,同时缩短检泵之后的产量恢复周期,进行了不压井作业技术研究,并研制了不压井作业装置。为解决起下抽油杆过程中的防喷问题,改进了抽油泵底阀结构,该结构可实现起下抽油杆过程中油管不带压、无溢流,并保障起下油管过程中的井控安全。该技术在江苏油田现场应用9井次,效果良好。 相似文献
125.
葛洲坝水利枢纽泄水建筑物进水口冲磨与修复 总被引:2,自引:1,他引:1
葛洲坝水利枢纽工程已运行20余年,近年水下检查中发现泄水建筑物进水口存在不同程度的冲磨,有些已威胁到建筑物安全运行,分析冲磨原因和探讨修复材料和手段是非常重要的,本文就此问题提出一些看法和建议供参考。 相似文献
126.
宁东供水工程供水水泵共有卧式和立式离心泵2种方案可供选择,也是工程论证时争论的焦点,经综合比较及主机设备的国际招标,最终确定了奥地利安德里兹公司的卧式双吸中开式离心泵为宁东供水工程的供水水泵。 相似文献
127.
通过百泉泉区天然状态与超采状态下的水环境对比分析,并对岩溶水补给量和开采量进行计算,阐述恢复邢台百泉泉水流量的可行性,随着“引朱济邢”和“南水北调”供水工程的实施,邢台百泉水生态环境的恢复将变为现实。 相似文献
128.
文中对曲沃县水资源开发利用现状进行了认真分析,并从思想观念、管理体制、管理模式上提出了问题,为解决问题提出了相应对策。 相似文献
129.
130.
系统地论述了氧气底吹熔炼氧枪的结构、工作原理、设计计算方法、材质及蚀损机理.指出了延长氧枪使用寿命的措施。 相似文献