全文获取类型
收费全文 | 1331篇 |
免费 | 104篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 33篇 |
综合类 | 10篇 |
化学工业 | 303篇 |
金属工艺 | 58篇 |
机械仪表 | 75篇 |
建筑科学 | 34篇 |
矿业工程 | 8篇 |
能源动力 | 53篇 |
轻工业 | 139篇 |
水利工程 | 26篇 |
石油天然气 | 34篇 |
无线电 | 148篇 |
一般工业技术 | 213篇 |
冶金工业 | 67篇 |
原子能技术 | 10篇 |
自动化技术 | 234篇 |
出版年
2024年 | 2篇 |
2023年 | 17篇 |
2022年 | 35篇 |
2021年 | 77篇 |
2020年 | 84篇 |
2019年 | 94篇 |
2018年 | 109篇 |
2017年 | 113篇 |
2016年 | 95篇 |
2015年 | 55篇 |
2014年 | 91篇 |
2013年 | 154篇 |
2012年 | 101篇 |
2011年 | 88篇 |
2010年 | 78篇 |
2009年 | 62篇 |
2008年 | 52篇 |
2007年 | 30篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1984年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1445条查询结果,搜索用时 31 毫秒
1.
Homoisoflavonoids (3-benzylidene-4-chromanones) are considered as an infrequent flavonoid class, possessing multi-beneficial bioactivities. The present study gives an overview on phytochemical aspects of homoisoflavonoids, including utilized plant species, parts, extracts, and separation techniques. Overall, these compounds have mainly been isolated and identified from bulbs and rhizomes of the plants belonging to Asparagaceae and Fabaceae families, particularly the genera of Ophiopogon, Dracaena, Scilla, Polygonatum, and Caesalpinia. 相似文献
2.
Mahmoodi Javad Nezamabadi-pour Hossein Abbasi-Moghadam Dariush 《Multimedia Tools and Applications》2022,81(15):20945-20961
Multimedia Tools and Applications - With the rapid development of detecting violent behaviors in surveillance cameras, requests on systems that automatically recognize violent events are expanded.... 相似文献
3.
Kalai Selvan Ramalingam Karmegam Karuppiah Shiamala Devi Ramaiya Vivien How Enoch Kumar Perimal Hassan Sadeghi Naeini Sivasankar Sambasivam Kulanthayan KC Mani 《人机工程学与制造业中的人性因素》2019,29(5):426-434
Many occupations require workers to stand for long periods of time without proper interventions, which causes discomfort in the back and lower limbs. Therefore, this study aims to assess the effectiveness in alleviating body muscle discomfort during prolonged standing through the use of a calf massager. This study was conducted among male workers at a manufacturer with production line workers and the list was obtained from the HR Department and simple random sampling was done by number categorization. A total of 100 respondents (50 respondents for both the control and the experimental groups) participated in this study. The experiment took place in a room with a similar setup for the production line. Each respondent was requested to perform the simulated task for 2 hr. For the experimental group, the calf massager was turned on every 15 min. At every 15‐min interval after turning on the calf massager, respondents from both groups were required to evaluate their discomfort level on a Borg's scale CR‐10 questionnaire. The results showed that the level of body discomfort among respondents in the experimental group reduced (20–30%) compared with that of the control group. Multivariate analysis results revealed that the discomfort rating for the lower back, knees, thighs, calves, and feet was significantly lower (p < .05) among the experimental group compared with the control group. For lower body parts, the lower back region was statistically significant (p < .05) at the 90th, 105th, and 120th min; the thigh region was statistically significant (p < .05) at the 120th min; the knee region was statistically significant (p < .05) at the 105th and 120th min; the calf region was statistically significant (p < .05) at all minute intervals except the 15th and 45th min, while the feet region, was statistically significant at the 105th and 120th min. Therefore, this study indicates that calf massage treatment is capable of reducing body muscle discomfort during prolonged standing and highlights the significance of calf massage. 相似文献
4.
Parisa Solhi Sodeif Azadmard‐Damirchi Javad Hesari Hamed Hamishehkar 《International Journal of Dairy Technology》2020,73(1):226-233
The qualitative properties of processed cheese (PC) fortified with different levels of asparagus powder (AP) (0.5%, 1% and 1.5% wt/wt) were evaluated during storage. AP decreased the pH and lipolysis indexes and increased the phenolic content, antioxidant activity and proteolysis of the processed cheeses. AP made the structure of the cheese more elastic, increased the rigidity and decreased the spreadability compared with the control sample, which corresponded to the results obtained using dynamic oscillatory rheometry. The results showed that AP as a rich source of bioactive components could be used for the fortification of processed cheeses. 相似文献
5.
In crack detection and sizing by the alternating current field measurement technique, U-shaped wires or coils excited by a high-frequency AC current source can be used to induce the surface field in the workpiece. The authors present a modeling technique for the interaction of a fatigue crack in a ferromagnetic metal with the surface field resulting from an inducer with two U-shaped wires. This work is an extension of a previous modeling technique to have developed for infinitely long (one-dimensional) cracks. In the present technique, the boundary of the fatigue crack is approximated by a circular arc, leading to a formulation for an efficient computation of the field-flaw interaction. Various numerical and experimental results supporting the modeling and illustrating the behavior of the magnetic field and electric potential at the metal surface around circular-arc cracks are presented 相似文献
6.
M. Sadeghi A. Jauhiainen B. Liss E.Ö. Sveinbjörnsson O. Engström 《Solid-state electronics》1998,42(12):2233-2238
We simulate the charge carrier traffic between the energy bands and the interface states in structures like Al/SiO2/6H–SiC, Al/diamond/Si and Al/SIPOS/Si to explain their high frequency capacitance–voltage behavior. The structures have in common that traditional electrical measurement techniques performed at room temperature are prone to thermal non-equilibrium effects. This can result in large errors in the interface data extracted from such studies when thermal equilibrium conditions are assumed. In this work, high frequency capacitance–voltage data are compared to numerical simulations which include such thermal non-equilibrium conditions to enable more accurate estimates of interface state parameters in above-mentioned structures. 相似文献
7.
M. E. özsan D. R. Johnson M. Sadeghi D. Sivapathasundaram G. Goodlet M. J. Furlong L. M. Peter A. A. Shingleton 《Journal of Materials Science: Materials in Electronics》1996,7(2):119-125
Thin CdS films have been grown by chemical bath (CdCl2, thiourea, ammonia) deposition (CBD) on SnO2 (TO)-coated glass substrate for use as window materials in CdS/CdTe solar cells. High-resolution transmission electron microscopy revealed grains with an average size of 10 nm. The structure was predominantly hexagonal with a high density of stacking faults. The film crystallinity improved with annealing in air. Annealing in a CdCl2 flux increased the grain size considerably and reduced the density of stacking faults. The optical transmission of the as-deposited films indicated a band gap energy of 2.41 eV. Annealing in air reduced the band gap by 0.1 eV. Annealing in CdCl2 led to a sharper optical absorption edge that remained at 2.41 eV. Similar band gap values were obtained by photocurrent spectroscopy and electroabsorption spectroscopy (EEA) using an electrolyte contact. EEA spectra were broad for the as-deposited and air-annealed samples, but narrower for the CdCl2-annealed films, reflecting the reduction in stacking fault density. Donor densities of ca. 1017 cm –3 were derived from the film/electrolyte junction capacitance. 相似文献
8.
9.
Transmission pricing has become a major issue in the discussions about the deregulated electricity markets.Consequently,open access to the transmission system is one of the basic topics to allow competition among participants in the energy market.Transmission costs have an important impact on relative competition among participants in the energy market as well as on short-and long-term economic efficiencies of the whole electricity industry,although they represent only close to 10% of the energy market price.This paper deals with the design and tests of a transmission pricing method based on the optimal circuit prices derived from the economically adapted network(EAN).Prices derived from the EAN have the advantage of being in tune with the maximum revenue allowed to the owner of transmission assets and simplifying the optimal allocation of transmission costs among participants.Beginning from the conceptual design,the proposed method is tested on a three-bus network and on the IEEE 24-bus reliability test system. 相似文献
10.
Healthcare delivery is evolving from disease-centered to patient-centered care delivery where patients are active participants
in their healthcare delivery. This calls for more communication and collaboration among all healthcare actors. There is also
an increasing demand for personalized healthcare systems that provide effective information management, facilitate communication
and collaboration, and support applications to meet user requirements. To address these challenges, we need to advance the
integration and interoperability of healthcare applications in a controlled manner. Drawing upon a conceptual model from a
collaborative care case study, we identified a set of interoperability requirements and developed a Mashup based interoperability
framework. Our framework allows patients and other healthcare actors to engage in collaborative processes through online applications
facilitated by mashups. We then use proof-of-concept implementations to demonstrate how our framework is able to facilitate
different types of interoperability. We believe that collaborative technologies such as mashups can implement process interoperability
requirements to support collaborative care delivery, particularly for asynchronous care delivery. 相似文献