全文获取类型
收费全文 | 801篇 |
免费 | 39篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 190篇 |
金属工艺 | 14篇 |
机械仪表 | 19篇 |
建筑科学 | 25篇 |
矿业工程 | 2篇 |
能源动力 | 100篇 |
轻工业 | 59篇 |
水利工程 | 4篇 |
石油天然气 | 6篇 |
无线电 | 105篇 |
一般工业技术 | 139篇 |
冶金工业 | 60篇 |
原子能技术 | 7篇 |
自动化技术 | 97篇 |
出版年
2024年 | 1篇 |
2023年 | 26篇 |
2022年 | 41篇 |
2021年 | 65篇 |
2020年 | 39篇 |
2019年 | 52篇 |
2018年 | 35篇 |
2017年 | 23篇 |
2016年 | 38篇 |
2015年 | 25篇 |
2014年 | 37篇 |
2013年 | 69篇 |
2012年 | 51篇 |
2011年 | 47篇 |
2010年 | 41篇 |
2009年 | 29篇 |
2008年 | 21篇 |
2007年 | 19篇 |
2006年 | 14篇 |
2005年 | 16篇 |
2004年 | 19篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 2篇 |
排序方式: 共有842条查询结果,搜索用时 31 毫秒
191.
Arif A. Anwar 《Canadian Metallurgical Quarterly》2000,126(1):57-63
Analytical equations are presented for two average pressure correction factors developed for linear displacement laterals with or without outflow at the downstream end. The average correction factor for laterals without downstream outflow, when applied to a relatively large number of outlets is in good agreement with earlier work. For a relatively small number of outlets, the average correction factor presented is more accurate. The average correction factor for laterals with outflow reduces to that for laterals without outflow when the outflow ratio is reduced to zero. For a relatively large number of outlets, this average correction factor is primarily a function of the outflow ratio. For both large outflow ratios and large outlet numbers, the average correction factor is almost a constant. To apply the average correction factor to design a tapered lateral, an expression relating lateral inlet head to required average head and friction head loss has been developed. The expression can be applied to a lateral with any number of reaches with different diameters. A practical application has been demonstrated through an example. 相似文献
192.
Copper-nickel alloys have been electrodeposited on steel substrates from a bath containing copper sulphate, nickel sulphate, sodium sulphate, sodium citrate and boric acid. Galvanostatic cathodic polarization, cathodic current efficiency and composition of the alloys were studied as influenced by bath composition, current density and temperature.The bath is characterized by high cathodic current efficiency. Current density is found to strongly influence the composition of the deposits. At low current densities (lower than a certain transition current density), a copper-rich alloy is deposited with copper (the more noble metal) being the preferentially deposited metal. At larger current densities, nickel becomes the nobler metal and is deposited preferentially. The magnitude of the transition current density depends upon the bath composition and temperature. The structure and surface morphology of the as-deposited alloys were examined by XRD and SEM. The results reveal the presence of a single solid solution phase with face centred cubic structure. The morphology of the deposits is mainly controlled by the alloy composition. 相似文献
193.
Effect of Aqueous Enzymatic Processes on Sunflower Oil Quality 总被引:2,自引:0,他引:2
The use of enzymes in aqueous vegetable oilseed extraction for simultaneous recovery of high quality oil and protein is gaining
recognition. In the present work, five enzyme preparations [Protex 7L by Genencor (Rochester, NY USA), Alcalase 2.4L, and
Viscozyme L by Novozymes (Bagsvaerd, Denmark), Natuzyme by Bioproton Pty Ltd (Australia) and Kemzyme by Kemin Europa N·V.
(Belgium)] were studied to evaluate their effects on the extraction of oil and protein from sunflower seeds. Preliminary experiments
were conducted for the selection of enzymes, optimum enzyme concentration, incubation time and pH. Maximum oil yield (87.25%
of the total oil in the seed) was obtained with Viscozyme L, whereas, Protex 7L offered the highest level of protein in the
aqueous phase. The comparison of the quality attributes of enzyme-assisted aqueous extracted (EAAE) oil with those of solvent-extracted
and control (oils extracted without enzyme treatment) oils revealed no significant (P > 0.05) variations for iodine value, density, refractive index, unsaponifiable matter, and fatty acid composition among the
extraction methods. The control and EAAE oils also exhibited a better oxidation state. The tocopherol concentration for the
oils, produced with the enzymes, was noted to be quite improved relative to the control and solvent-extracted oils. A higher
antioxidant activity in terms of total phenolic contents, 2,2′-diphenyl-1-picrylhydrazyl scavenging capacity and inhibition
of linoleic acid peroxidation was also observed for the EAAE oils as against control and the solvent-extracted oils. 相似文献
194.
195.
Percentage of body fat is strongly associated with the risk of several chronic diseases but its accurate measurement is difficult.
Bioelectrical impedance analysis (BIA) is a relatively simple, quick and non-invasive technique, to measure body composition.
It measures body fat accurately in controlled clinical conditions but its performance in the field is inconsistent. In large
epidemiologic studies simpler surrogate techniques such as body mass index (BMI), waist circumference, and waist-hip ratio
are frequently used instead of BIA to measure body fatness. We reviewed the rationale, theory, and technique of recently developed
systems such as foot (or hand)-to-foot BIA measurement, and the elements that could influence its results in large epidemiologic
studies. BIA results are influenced by factors such as the environment, ethnicity, phase of menstrual cycle, and underlying
medical conditions. We concluded that BIA measurements validated for specific ethnic groups, populations and conditions can
accurately measure body fat in those populations, but not others and suggest that for large epdiemiological studies with diverse
populations BIA may not be the appropriate choice for body composition measurement unless specific calibration equations are
developed for different groups participating in the study. 相似文献
196.
Gilanie Ghulam Bajwa Usama Ijaz Waraich Mustansar Mahmood Anwar Muhammad Waqas 《Multimedia Tools and Applications》2021,80(3):4295-4306
Multimedia Tools and Applications - Astrocytoma is the most common and aggressive brain tumor, in its highest grade, the prognosis is ‘low survival rate’. Spinal tap and biopsy are the... 相似文献
197.
Nurul Anwar Tommi Sappinen Kalle Jalava Juhani Orkas 《Advanced Powder Technology》2021,32(6):1902-1910
A good sand mold is an indispensable prerequisite to obtaining a good metal casting. Although sand casting is one of the oldest metal forming technique known to humans, it still has a lot to discover. In a bid to meet the ever-growing demand for quality, economics and increasing environmental restrictions, research is still ongoing to optimize for example the process of making the sand mold. This paper presents a comparative study of six different foundry sands for flowability using simple inexpensive apparatus and some quality parameters achieved by these sands when used with three different types of binder, two organic and one inorganic. The study aims to facilitate the choice of mold materials with a more extensive outlook into their characteristics through a serious of sand and mold tests. A good comparison of already existing materials provides a good reference point when novel materials are investigated. All the sands exhibited ‘good’ flow property according to the simple flowability tests done. However, not the same consensus for flowability rank is reached by all the flow tests. The mold quality tests reveal the strength, loss on ignition and permeability values achieved with each of the binder and sand combination which can also be used in mold material selection. 相似文献
198.
Ali Aamir Ullah Matee Barkat Adnan Raza Waleed Ahmed Qadir Anwar Qamar Zia ul 《Bulletin of Engineering Geology and the Environment》2021,80(12):9217-9235
Bulletin of Engineering Geology and the Environment - Most of the surface wave-based geophysical methods require an accurate estimate of the shear wave velocity (Vs) for geotechnical site... 相似文献
199.
Mostak AhmedMohammad B. Khan Mubarak A. KhanS. Shamsul Alam Md. Abdul HalimM. Anwar H. Khan 《Journal of power sources》2011,196(2):614-619
Polymer electrolyte membranes (PEMs) were successfully prepared by simultaneous ultraviolet (UV) radiation-induced graft copolymerization of styrene (35 vol.% concentration) onto poly(ethyleneterephthalate) (PET) film, followed by sulfonation on the styrene monomer units in the grafting chain using 0.05 M chlorosulfonic acid (ClSO3H). The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses as well as Fourier Transform Infrared (FTIR) spectroscopy. The maximum ion-exchange capacity (IEC) of the PEM was measured to be 0.04385 mmol g−1 at its highest level of grafting and sulfonation. They exhibited high thermal and mechanical properties as well as oxidative stability. They are highly stable in H2SO4 solutions and can be used in the acidic fuel cells. The membranes showed low water uptake as well as low proton conductivity than Nafion. In this study, the preparation of PEMs from commodity-type polymers is found to be very inexpensive and is a suitable candidate for applications in fuel cells. 相似文献
200.
Afzal Badshah Anwar Ghani Muhammad Ahsan Qureshi Shahaboddin Shamshirband 《计算机、材料和连续体(英文)》2019,61(1):81-101
Educational institutions are soft targets for the terrorist with massive and defenseless people. In the recent past, numbers of such attacks have been executed around the world. Conducting research, in order to provide a secure environment to the educational institutions is a challenging task. This effort is motivated by recent assaults, made at Army Public School Peshawar, following another attack at Charsada University, Khyber Pukhtun Khwa, Pakistan and also the Santa Fe High School Texas, USA massacre. This study uses the basic technologies of edge computing, cloud computing and IoT to design a smart emergency alarm system framework. IoT is engaged in developing this world smarter, can contribute significantly to design the Smart Security Framework (SSF) for educational institutions. In the emergency situation, all the command and control centres must be informed within seconds to halt or minimize the loss. In this article, the SSF is proposed. This framework works on three layers. The first layer is the sensors and smart devices layer. All these sensors and smart devices are connected to the Emergency Control Room (ECR), which is the second layer of the proposed framework. The second layer uses edge computing technologies to process massive data and information locally. The third layer uses cloud computing techniques to transmit and process data and information to different command and control centres. The proposed system was tested on Cisco Packet Tracer 7. The result shows that this approach can play an efficient role in security alert, not only in the educational institutions but also in other organizations too. 相似文献