全文获取类型
收费全文 | 680篇 |
免费 | 41篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 5篇 |
综合类 | 2篇 |
化学工业 | 115篇 |
金属工艺 | 16篇 |
机械仪表 | 33篇 |
建筑科学 | 28篇 |
矿业工程 | 1篇 |
能源动力 | 100篇 |
轻工业 | 48篇 |
水利工程 | 1篇 |
石油天然气 | 4篇 |
无线电 | 43篇 |
一般工业技术 | 167篇 |
冶金工业 | 55篇 |
原子能技术 | 8篇 |
自动化技术 | 102篇 |
出版年
2024年 | 3篇 |
2023年 | 12篇 |
2022年 | 22篇 |
2021年 | 55篇 |
2020年 | 32篇 |
2019年 | 24篇 |
2018年 | 27篇 |
2017年 | 36篇 |
2016年 | 39篇 |
2015年 | 16篇 |
2014年 | 23篇 |
2013年 | 48篇 |
2012年 | 31篇 |
2011年 | 49篇 |
2010年 | 49篇 |
2009年 | 41篇 |
2008年 | 29篇 |
2007年 | 37篇 |
2006年 | 25篇 |
2005年 | 15篇 |
2004年 | 14篇 |
2003年 | 20篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 16篇 |
1999年 | 16篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有728条查询结果,搜索用时 78 毫秒
71.
This study deals with an energy and exergy analysis of Salihli geothermal district heating system (SGDHS) in Manisa, Turkey. In the analysis, actual system data are used to assess the district heating system performance, energy and exergy efficiencies, specific exergy index, exergetic improvement potential and exergy losses. Energy and exergy losses throughout the SGDHS are quantified and illustrated in the flow diagram. The exergy losses in the system, particularly due to the fluid flow, take place in the pumps and the heat exchanger, as well as the exergy losses of the thermal water (e.g. geothermal fluid) and the natural direct discharge of the system. As a result, the total exergy losses account for 2.22, 17.88 and 20.44%, respectively, of the total exergy input to the entire SGDHS. The overall energy and exergy efficiencies of the SGDHS components are also studied to evaluate their individual performances and determined to be 55.5 and 59.4%, respectively. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
72.
In the present work, change of rod-like micelle sizes with change of amphiphile concentration in hexagonal mesophase and the effect of inorganic salt additions on the effective length of these micelles have been studied. The investigations were made by the using of electrical conductivity method in shear flow. The dependence of form factor on the anisometricity parameter of rod-like micelles were determined for investigated lyotropic systems. 相似文献
73.
A. M. Klimova V. A. Ananichev Mohammad Arif L. N. Blinov 《Glass Physics and Chemistry》2005,31(6):760-762
Temperature dependences of the saturated vapor pressure of elemental zinc (873–1234 K) and selenium (730–1063 K), as well as zinc selenide (673–1373 K), are investigated using the gravimetric method. Analysis of the experimental data demonstrates that these dependences can be adequately described by equations of the form logP = ?A/T+B. The saturated vapor pressures calculated for zinc from the data obtained with the developed gravimetric method are in good agreement with those available in the literature. 相似文献
74.
M. Arif Khan Nazar A. Shah A. Ali M. Basharat M. A. Hannan A. Maqsood 《Journal of Coatings Technology and Research》2009,6(2):251-256
Cd-enriched cadmium telluride (CdTe) polycrystalline films were grown on corning glass substrates by close spaced sublimation
(CSS) technique. To our knowledge, Cd-enriched CdTe thin films by CSS have not been reported earlier. The structural investigations
performed by means of X-ray diffraction (XRD) technique, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy
(EDX) showed that the deposited films exhibit a polycrystalline structure with 〈111〉 as preferred orientation. The structural,
optical, and electrical properties of these films were analyzed as a function of the Cd concentration. For the films having
an excess of Cd, the electrical resistivity dropped several orders of magnitude. The deposited films also showed that the
value of resistivity decreased with increasing temperature manifesting the semiconducting behavior of the films. The results
showed that using this deposition technique, n-type Cd-enriched CdTe polycrystalline film could be produced. 相似文献
75.
Saba Gul Mushtaq Ahmad Muhammad Zafar Saraj Bahadur Shazia Sultana Najla Begum Syed Nasar Shah Wajid Zaman Fazal Ullah Asma Ayaz Uzma Hanif 《Microscopy research and technique》2019,82(7):1021-1031
The present study is insight into pollen morphology for characterizing species and their utility in the taxonomic separation of certain taxa of subfamily Nepetoideae (Lamiaceae) from Pakistan. The pollen micromorphology of 11 species of the Nepetoideae was analyzed and documented using light microscopy and scanning electron microscopy (SEM) for both qualitative and quantitative characteristics. Most species have hexazonocolpate pollen grains but trizonocolpate and tetrazonocolpate pollen with circular and oval amb were also rarely observed in Mentha spicata. The basic pollen shape in most of the studied species was subspheroidal but prolate grains were also observed in M. spicata, S. coccinea, and S. plebeia. The exine sculpturing of Nepetoideae pollen was taxonomically very informative particularly at subfamily level. Observations of exine sculpturing with SEM revealed various types of pollen grains: reticulate, bireticulate, microreticulate, perforate, aerolate, and gammate. The bireticulate type further subdivided into three subtypes based on the number of secondary lumina in each primary lumen and is characterized by varying characteristics of the secondary reticulum and primary muri. A significant variation was observed in colpus surface ornamentation. The maximum polar diameter was found in O. americanum (58 ± 5.8 μm) and the maximum equatorial diameter observed in O. basilicum (50.25 ± 1.37 μm). Pollen features of the studied species were discussed and compared based on the current taxonomical concepts. The results showed that pollen traits of the subfamily Nepetoideae was found significant to classify the taxa. Furthermore, pollen features provide additional evidence to distinguish macromorphologically similar taxa from each other. 相似文献
76.
77.
Muhammad Shoaib Arif Ali Raza Muhammad Rafiq Mairaj Bibi Rabia Fayyaz Mehvish Naz Umer Javed 《计算机、材料和连续体(英文)》2019,59(3):787-804
In this paper, a reliable stochastic numerical analysis for typhoid fever incorporating with protection against infection has been considered. We have compared the solutions of stochastic and deterministic typhoid fever model. It has been shown that the stochastic typhoid fever model is more realistic as compared to the deterministic typhoid fever model. The effect of threshold number T* hold in stochastic typhoid fever model. The proposed framework of the stochastic non-standard finite difference scheme (SNSFD) preserves all dynamical properties like positivity, bounded-ness and dynamical consistency defined by Mickens, R. E. The stochastic numerical simulation of the model showed that increase in protection leads to low disease prevalence in a population. 相似文献
78.
79.
Abdoos Majid Rawal Sushant Arif Abul Fazal M. Veldhuis Stephen C. 《The International Journal of Advanced Manufacturing Technology》2020,106(7):2793-2803
The International Journal of Advanced Manufacturing Technology - Beside machining condition and parameters, coating properties is one of the main factors affecting tool performance and wear... 相似文献
80.
Guzel Muhammed Huseyin Unal Recep Emre Onder Ahmet Sen Muhammed Arif Kose Faruk 《Journal of Mechanical Science and Technology》2021,35(3):1301-1308
Journal of Mechanical Science and Technology - The energy demand of world is increasing worldwide because of increasing population and developing technology. The use of environmentally friendly... 相似文献