全文获取类型
收费全文 | 580篇 |
免费 | 50篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 10篇 |
综合类 | 4篇 |
化学工业 | 105篇 |
金属工艺 | 13篇 |
机械仪表 | 39篇 |
建筑科学 | 5篇 |
能源动力 | 54篇 |
轻工业 | 81篇 |
水利工程 | 3篇 |
无线电 | 43篇 |
一般工业技术 | 147篇 |
冶金工业 | 26篇 |
原子能技术 | 1篇 |
自动化技术 | 103篇 |
出版年
2024年 | 6篇 |
2023年 | 14篇 |
2022年 | 67篇 |
2021年 | 81篇 |
2020年 | 40篇 |
2019年 | 49篇 |
2018年 | 48篇 |
2017年 | 42篇 |
2016年 | 39篇 |
2015年 | 21篇 |
2014年 | 28篇 |
2013年 | 31篇 |
2012年 | 21篇 |
2011年 | 26篇 |
2010年 | 9篇 |
2009年 | 14篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 10篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 15篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有634条查询结果,搜索用时 15 毫秒
621.
Zeeshan Ur Rehman Seong Hun Shin Imad Hussain Bon Heun Koo 《Protection of Metals and Physical Chemistry of Surfaces》2017,53(3):495-502
Detail study of the PEO coatings produced on AZ31B magnesium alloy in Na2SiO3–K2ZrF6-based electrolyte solution was carried out in this work. ZrO2, MgF2, MgO and Mg2SiO4 were observed as the major phases in the coatings. Electrolytic decomposition and then the severe thermochemical environment provoked various Zr–F–Mg based complexes in the coatings. From the surface analysis, various structures e.g, nano-grains, pores and volcano shape sintered material were evidenced. Using Vicker hardness test, maximum hardness was recorded as ~1280 HV. Potentiodynamic polarization technique in 3.5 wt % NaCl solution was used to predict the corrosion performances of the specimens. Among the coated samples, highest corrosion resistance was recorded to be ~223.5 × 103 kΩ/cm2 for 15 min coatings. 相似文献
622.
Ahsan Irshad Huijun Guo Shoaib Ur Rehman Jiayu Gu Chaojie Wang Hongchun Xiong Yongdun Xie Shirong Zhao Luxiang Liu 《International journal of molecular sciences》2022,23(18)
Several health benefits are obtained from resistant starch, also known as healthy starch. Enhancing resistant starch with genetic modification has huge commercial importance. The variation of resistant starch content is narrow in wheat, in relation to which limited improvement has been attained. Hence, there is a need to produce a wheat population that has a wide range of variations in resistant starch content. In the present study, stable mutants were screened that showed significant variation in the resistant starch content. A megazyme kit was used for measuring the resistant starch content, digestible starch, and total starch. The analysis of variance showed a significant difference in the mutant population for resistant starch. Furthermore, four diverse mutant lines for resistant starch content were used to study the quantitative expression patterns of 21 starch metabolic pathway genes; and to evaluate the candidate genes for resistant starch biosynthesis. The expression pattern of 21 starch metabolic pathway genes in two diverse mutant lines showed a higher expression of key genes regulating resistant starch biosynthesis (GBSSI and their isoforms) in the high resistant starch mutant lines, in comparison to the parent variety (J411). The expression of SBEs genes was higher in the low resistant starch mutants. The other three candidate genes showed overexpression (BMY, Pho1, Pho2) and four had reduced (SSIII, SBEI, SBEIII, ISA3) expression in high resistant starch mutants. The overexpression of AMY and ISA1 in the high resistant starch mutant line JE0146 may be due to missense mutations in these genes. Similarly, there was a stop_gained mutation for PHO2; it also showed overexpression. In addition, the gene expression analysis of 21 starch metabolizing genes in four different mutants (low and high resistant starch mutants) shows that in addition to the important genes, several other genes (phosphorylase, isoamylases) may be involved and contribute to the biosynthesis of resistant starch. There is a need to do further study about these new genes, which are responsible for the fluctuation of resistant starch in the mutants. 相似文献
623.
Hafiz Mamoon Rehman Shengjie Chen Shoudong Zhang Memoona Khalid Muhammad Uzair Phillip A. Wilmarth Shakeel Ahmad Hon-Ming Lam 《International journal of molecular sciences》2022,23(21)
Cultivated soybean (Glycine max (L.)), the world’s most important legume crop, has high-to-moderate salt sensitivity. Being the frontier for sensing and controlling solute transport, membrane proteins could be involved in cell signaling, osmoregulation, and stress-sensing mechanisms, but their roles in abiotic stresses are still largely unknown. By analyzing salt-induced membrane proteomic changes in the roots and leaves of salt-sensitive soybean cultivar (C08) seedlings germinated under NaCl, we detected 972 membrane proteins, with those present in both leaves and roots annotated as receptor kinases, calcium-sensing proteins, abscisic acid receptors, cation and anion channel proteins, proton pumps, amide and peptide transporters, and vesicle transport-related proteins etc. Endocytosis, linoleic acid metabolism, and fatty acid biosynthesis pathway-related proteins were enriched in roots whereas phagosome, spliceosome and soluble NSF attachment protein receptor (SNARE) interaction-related proteins were enriched in leaves. Using label-free quantitation, 129 differentially expressed membrane proteins were found in both tissues upon NaCl treatment. Additionally, the 140 NaCl-induced proteins identified in roots and 57 in leaves are vesicle-, mitochondrial-, and chloroplast-associated membrane proteins and those with functions related to ion transport, protein transport, ATP hydrolysis, protein folding, and receptor kinases, etc. Our proteomic results were verified against corresponding gene expression patterns from published C08 RNA-seq data, demonstrating the importance of solute transport and sensing in salt stress responses. 相似文献
624.
以凝血酶比活力为响应值,在单因素实验的基础上,筛选出激活时间、激活温度、Ca2+浓度三个对激活影响较大的因素,响应面法进行优化,并验证优化方案。结果表明,凝血酶原激活工艺的优化参数为:激活时间为2.8h,温度为32℃,Ca+2浓度为0.11mol/L。在此条件下,凝血酶比活力为51.16U/mg。 相似文献
625.
Yu Zhang Tianshan Ma Rehman S. Abdul Sharif Arshian Janjua Laeeq 《Clean Technologies and Environmental Policy》2023,25(5):1473-1484
Clean Technologies and Environmental Policy - This paper studies the competition between the illegal recycling group and the legitimate recycling group in the recycling market of end-of-life... 相似文献
626.
Sumbal Zahoor Ishtiaq Ahmad Ateeq Ur Rehman Elsayed Tag Eldin Nivin A. Ghamry Muhammad Shafiq 《计算机、材料和连续体(英文)》2023,75(1):311-327
The development of the Next-Generation Wireless Network
(NGWN) is becoming a reality. To conduct specialized processes more, rapid
network deployment has become essential. Methodologies like Network
Function Virtualization (NFV), Software-Defined Networks (SDN), and
cloud computing will be crucial in addressing various challenges that 5G
networks will face, particularly adaptability, scalability, and reliability. The
motivation behind this work is to confirm the function of virtualization
and the capabilities offered by various virtualization platforms, including
hypervisors, clouds, and containers, which will serve as a guide to dealing
with the stimulating environment of 5G. This is particularly crucial when
implementing network operations at the edge of 5G networks, where limited
resources and prompt user responses are mandatory. Experimental results
prove that containers outperform hypervisor-based virtualized infrastructure
and cloud platforms’ latency and network throughput at the expense of higher
virtualized processor use. In contrast to public clouds, where a set of rules is
created to allow only the appropriate traffic, security is still a problem with
containers. 相似文献
627.
Zia ur Rehman Mulika Fatima Ahmad Khan Sajid Shah Raja Wasim Ahmad Ahmad Din Attiqa Rehman 《International Journal of Communication Systems》2023,36(12):e4265
A smart community grid is an electrical network, which connects several producers, consumers, and prosumers to share energy in an intelligent and secure way. The main challenges of smart community grid are demand response, demand bidding, dynamic electricity tariffs, demand-side management, and prosumers handling. The current state-of-the-art smart grid decision making is focused on consumers and producers behavior while the aim of this research is to achieve prosumer's different goals in an optimized and intelligent way. A genetic algorithm (GA)-based solution is proposed to share energy in an optimized way without affecting the prosumers' preferences. Six prosumers smart community grids data sets are used to validate the performance of the proposed system. The results show that the proposed method significantly improves the loss of energy sharing without compromising the user's preferences. 相似文献
628.
Forschung im Ingenieurwesen - This study was performed to optimize the single slope solar still with internally reflecting walls and externally reflecting, top and bottom, flat booster reflectors... 相似文献
629.
Silicon - An overview of the Passivated Emitter and Rear Totally Diffused (PERT) solar cell is presented, which is a member of Passivated Emitter and Rear Contact (PERC) family. Due to its... 相似文献
630.
Muhammad Irfan Wasi Ur Rehman Khan Sadiq Ullah Naveed Mufti Muhammad Fawad Khan Rizwan Ullah Usman Ali Fazal Muhammad Faisal Althobiani Mohammed Alshareef Shadi Alghaffari Saifur Rehman V. R. Shamji 《计算机系统科学与工程》2023,45(3):2693-2704
This paper presents, a novel cactus shaped frequency reconfigurable antenna for sub 10 GHz wireless applications. PIN diode is utilized as an electrical switch to achieve reconfigurability, enabling operation in four different frequency ranges. In the switch ON state mode, the antenna supports 2177–3431 and 6301–8467 MHz ranges. Alternatively, the antenna resonates within 2329–3431 and 4951–6718 MHz while in the OFF state mode. Radiation efficiency values, ranging from 68% to 84%, and gain values, ranging from 1.6 to 4 dB, in the operating frequency bands. the proposed antenna satisfy the practical requirements and expectations. The overall planner dimensions of the proposed antenna model is 40 × 21 mm2. Moreover, the measurement results from the prototype support the simulation results. Based on the frequency ranges supported by the antenna, it can be used for multiple wireless standards and services, including Worldwide interoperability and Microwave Access (WiMAX), Wireless Fidelity (Wi-Fi), Bluetooth, Long Term Evolution (LTE) and satellite communications. This increases its applicability for use in mobile terminals. 相似文献