首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   9874篇
  免费   523篇
  国内免费   188篇
电工技术   906篇
综合类   625篇
化学工业   1472篇
金属工艺   443篇
机械仪表   718篇
建筑科学   995篇
矿业工程   700篇
能源动力   431篇
轻工业   560篇
水利工程   412篇
石油天然气   501篇
武器工业   41篇
无线电   291篇
一般工业技术   576篇
冶金工业   1210篇
原子能技术   55篇
自动化技术   649篇
  2024年   10篇
  2023年   77篇
  2022年   160篇
  2021年   225篇
  2020年   233篇
  2019年   128篇
  2018年   148篇
  2017年   139篇
  2016年   208篇
  2015年   243篇
  2014年   705篇
  2013年   506篇
  2012年   837篇
  2011年   846篇
  2010年   614篇
  2009年   551篇
  2008年   470篇
  2007年   666篇
  2006年   609篇
  2005年   590篇
  2004年   508篇
  2003年   463篇
  2002年   361篇
  2001年   310篇
  2000年   269篇
  1999年   165篇
  1998年   135篇
  1997年   115篇
  1996年   92篇
  1995年   49篇
  1994年   41篇
  1993年   20篇
  1992年   30篇
  1991年   12篇
  1990年   12篇
  1989年   9篇
  1988年   7篇
  1987年   3篇
  1986年   2篇
  1985年   2篇
  1983年   1篇
  1981年   3篇
  1980年   1篇
  1979年   3篇
  1977年   1篇
  1973年   1篇
  1967年   1篇
  1965年   1篇
  1964年   2篇
  1958年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
An atmospheric pressure argon plasma brush with air addition is employed to treat polyethylene terephthalate(PET) surface in order to improve its hydrophilicity. Results indicate that the plasma plume generated by the plasma brush presents periodically pulsed current despite a direct current voltage is applied. Voltage-current curve reveals that there is a transition from a Townsend discharge regime to a glow one during one discharge period. Optical emission spectrum indicates that more oxygen atoms are produced in the plume with increasing air content, which leads to the better hydrophilicity of PET surface after plasma treatment. Besides,an aging behavior is also observed. The hydrophilicity improvement is attributed to the production of oxygen functional groups, which increase in number with increasing air content.Moreover, some grain-like structures are observed on the treated PET surface, and its mean roughness increases with increasing air content. These results are of great importance for the hydrophilicity improvement of PET surface with a large scale.  相似文献   
2.
Brown rice noodles (RN) are typical whole-grain products with health benefits. This study investigated the effects of rice bran fermented with Lactobacillus plantarum on palatability, volatile profiles, and antioxidant activity of brown RN. Three kinds of RN, including RN, brown RN (BRN), and bran fermented RN (BFRN), were involved in this study. The results indicated that bran fermentation reduced the cooking loss of BFRN and improved the elongation and the sensory attributes of brown RN. After fermentation, aldehydes were significantly decreased while alcohols increased, and more pleasant flavours were shown in BFRN. Fermentation increased the content of free phenolics and decreased the content of bound phenolics. Among the four major phenolics detected in this study, ferulic acid was the most abundant one in all three RN samples. The DPPH radical scavenging activity and the ferric reducing antioxidant power of free phenolics in BFRN increased significantly compared to BRN. This study proved that rice bran fermentation is an effective approach to improve palatability, enrich the flavour as well as enhance the antioxidant activity of brown RN, which may facilitate the development of processing technology for brown RN.  相似文献   
3.
《Ceramics International》2022,48(6):7593-7604
The ceramic core, produced by hot injection molding, is one of the critical components for manufacturing high-performance aircraft engine turbine blades. However, the injection molding process will cause defects such as burrs and flashes in the fine structure of the formed ceramic core. Manual trimming is necessary, but the trimming quality is poor, and the yield is low. In this paper, the online trimming method of ceramic cores is studied. Based on the orthogonal experiment method, the optimal laser parameters for processing the ceramic core's porous multi-scale particle structure material were obtained. Further, the problems of the match head and tail phenomenon and dimensional accuracy improvement in trimming ceramic cores have been studied. A path optimisation method is proposed to improve the quality and accuracy of the trimming profile effectively. Finally, the overall process flow of ceramic core trimming is elaborated, and experimental verification is given. The results show that the ceramic core online trimming method proposed in this paper has advantages of high precision and high yield compared with the manual method, which will have substantial potential application value in the aviation field.  相似文献   
4.
Given the continuing issues of environment and energy, methane dry reforming for syngas production have sparked interest among researchers, but struggled with the process immaturity owing to catalyst deactivation. This review summarizes the recent advances in the development of efficient and stable catalysts with strong resistance to coking and metal sintering, including the application of novel materials, the assessment of advanced characterizations and the compatibility to improved reaction system. One feasible option is the crystalline oxide catalysts (perovskite, pyrochlore, spinel and LDHs), which feature a fine metal dispersion and surface confinement effect via a metal exsolution strategy and exhibit superior reactivity and stability. Some new materials (h-BN, clays and MOFs) also extend the option because of their unique morphology and microstructure. It also is elaborated that progresses were achieved in advanced characterizations application, leading to success in the establishment of reaction mechanisms and attributions to the formed robust catalysts. In addition, the perspective described the upgrade of reaction system to a higher reaction efficiency and milder reaction conditions. The combination of efficient reaction systems and robust catalysts paves a way for a scaling-up application of the process.  相似文献   
5.
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   
6.
《云南化工》2019,(8):117-120
介绍了国内首个IGCC示范工程概况,详细描述REXA执行器的工作原理和操作方法,列举REXA执行器在天津IGCC中的应用以及出现过的问题,以期供今后国内IGCC建设参考。  相似文献   
7.
《Soils and Foundations》2021,61(6):1529-1542
Biocemented soil columns were created at a reduced scale (mid-scale) using enzyme-induced carbonate precipitation (EICP) as a prelude to field scale deployment. Approximately 0.3 m diameter × 0.75 m long columns were created using a tube-à-manchette grouting technique in 0.6 m × 0.6 m × 1.2 m boxes filled with a dry washed quarry sand. Treatment solution composition and treatment protocol, including number of cycles of treatment and time interval between cycles, were established based upon laboratory testing. The urease enzyme used in the treatment solution was extracted from jack beans in a just-in-time manner on site. The biocemented soil columns were characterized in situ using shear wave velocity, needle penetrometer and pocket penetrometer testing, dimensional measurements, and by unconfined compression strength (UCS) and carbonate content measurements on specimens recovered from the columns. The in situ measurements indicated the target UCS of 500 kPa was achieved. However, the UCS tests on recovered specimens had inconsistent results, which may be attributed to sample disturbance. Overall, the results demonstrate that EICP is a viable method for creating biocemented soil columns for ground improvement.  相似文献   
8.
以ISP40报告中STORM试验的SR11工况试验条件为基础,对GASFLOW中再悬浮模型进行适用性评估,根据试验数据所反映出的气体流速与再悬浮最小粒径的关系,对GASFLOW中再悬浮模型进行了改进。研究结果表明,GASFLOW中原再悬浮模型的分析结果与SR11工况的试验结果有较为明显的差距,改进后的模型无论在变化趋势还是数值上均与试验结果更加吻合,并且保证了源项估算的保守性。考虑到STORM试验与严重事故下实际安全壳环境条件差距较大,建议开展更为接近实际状况的试验,以提升再悬浮模型分析的准确性。  相似文献   
9.
10.
目前没有针对纳米封堵剂封堵效果评价的方法。在室内进行评价时,实验结果往往会无法反映出纳米颗粒的封堵作用。在借鉴现有评价方法的基础上,通过对滤失介质的选择和改善,形成了渗透性滤失评价方法。该方法可操作性高,能反映出纳米颗粒的封堵效果,并通过对不同粒径的纳米颗粒封堵效果的评价对该方法进行了验证。该方法对于纳米颗粒的评价和在现场施工中的选择都有一定评价参考作用。   相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号