全文获取类型
收费全文 | 928篇 |
免费 | 76篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 19篇 |
综合类 | 10篇 |
化学工业 | 197篇 |
金属工艺 | 27篇 |
机械仪表 | 35篇 |
建筑科学 | 46篇 |
矿业工程 | 6篇 |
能源动力 | 59篇 |
轻工业 | 108篇 |
水利工程 | 17篇 |
石油天然气 | 8篇 |
无线电 | 82篇 |
一般工业技术 | 188篇 |
冶金工业 | 25篇 |
原子能技术 | 7篇 |
自动化技术 | 178篇 |
出版年
2024年 | 1篇 |
2023年 | 20篇 |
2022年 | 23篇 |
2021年 | 53篇 |
2020年 | 60篇 |
2019年 | 47篇 |
2018年 | 96篇 |
2017年 | 56篇 |
2016年 | 90篇 |
2015年 | 43篇 |
2014年 | 76篇 |
2013年 | 135篇 |
2012年 | 64篇 |
2011年 | 58篇 |
2010年 | 47篇 |
2009年 | 30篇 |
2008年 | 16篇 |
2007年 | 26篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1012条查询结果,搜索用时 15 毫秒
91.
Elham Poonaki Mohammad Esfandyar Hadi Hejazinia Seyed Esmaeil Sadat Ebrahimi Morteza Pirali Hamedani Jafar Farzaneh Mehdi Shafiee Ardestani 《IET nanobiotechnology / IET》2020,14(6):470
Gadolinium as a contrast agent in MRI technique combined with DTPA causes contrast induced nephropathy (CIN) and nephrogenic systemic fibrosis (NSF) which can reduce by usage of antioxidants such as N‐acetyl cysteine by increasing the membrane''s permeability leads to lower cytotoxicity. In this study, N ‐acetyl cysteine‐PLGA Nano‐conjugate was synthesized according to stoichiometric rules of molar ratios andafter assessment by FTIR, NMR spectroscopy and Atomic Force Microscopy (AFM) imaging was combined with Magnevist® (gadopentetate dimeglumine) and its effects on the renal cells were evaluated. MTT [3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐Diphenyltetrazolium Bromide] and cellular uptake assays have indicated relatively significant toxicity of magnevist (P < 0.05) on three cell lines including HEK293, MCF7 and L929 compared to other synthesized ligands that shown no toxicity. Moreover, systemic evaluation has shown no notable changes of blood urea nitrogen (BUN) and creatinine in kidney of mice. In consequence, antioxidant effect was increased as well as the renal toxicity of the contrast agent reduced at the cell level. As a result, PLGA‐NAC nano‐conjugate can be a promising choice for decreasing the magnevist toxicity for treatment and prevention of CIN and will be able to open a new horizon to research on reduction of toxicity of contrast agents by using nanoparticles.Inspec keywords: blood, toxicology, nanofabrication, cellular biophysics, biomedical materials, nanoparticles, chromatography, cancer, biodegradable materials, biomedical MRI, kidney, pH, nanomedicine, patient treatment, diseases, atomic force microscopy, Fourier transform infrared spectraOther keywords: cellular toxicity, gadopentate dimeglumine, contrast agent, magnetic resonance imaging technique, diethylenetriamine pentaacetate, contrast‐induced nephropathy, nephrogenic systemic fibrosis, stoichiometric rules, molar ratios, dimethyl sulphoxide solution, chromatography techniques, nuclear magnetic resonance spectroscopy, atomic force microscopy imaging, Magnevist®, gadopentetate dimeglumine, renal cells, MTT cytotoxicity, human embryonic kidney‐293, L929 cell lines, in vitro conditions, cellular uptake assays, Magnevist uptake, antioxidant effect, renal toxicity, cell level, PLGA nanocarrier, acetylcysteine nanoconjugate, Magnevist toxicity, N‐acetylcysteine–PLGA nano‐conjugate, N‐acetyl cysteine‐poly‐lactic‐co‐glycolic acid nanoconjugate 相似文献
92.
The crosstalk and coupling of the external fields on orthogonal microstrip transmission lines in different layers have significant
effects on signal quality in MMIC and PCBs. In this paper the crosstalk is analyzed in detail using both full-wave and quasi-static
methods. The used full wave method is mixed potential integral equation method of moment (MPIEMoM). Because of the weak coupling between lines, the effect of the incident plane-wave is studied by applying transmission
line theory in a scattered voltage formulation uses quasi-TEM propagation model for each interconnection and the exact distribution
of the incident electric field within the layers. Afterward, by using the predetermined lumped circuit model of the cross-region,
the effect of coupling between two lines is calculated and then applied to terminal voltages in 1–20 GHz frequency range which
results in the final terminal voltages. 相似文献
93.
Abstract—This article proposes a method that enables ideal sharing of reactive power among converter-based micro-sources in a microgrid with a decentralized control strategy. Power sharing must be properly performed among micro-sources to avoid circulating currents or overloading. Using conventional droop characteristics to achieve power sharing is not satisfactory, as system asymmetry will greatly impact the quality of sharing. In the proposed method, droop characteristic parameters are modified upon a change in system operating point such that ideal sharing takes place after the modification process. Simulation results are presented to show the validity of analysis. 相似文献
94.
Acoustic emission characterization of damage in short hemp‐fiber‐reinforced polypropylene composites
Mustapha Assarar Daniel Scida Wajdi Zouari El Hadi Saidane Rezak Ayad 《Polymer Composites》2016,37(4):1101-1112
This article aims at investigating the effects of hygrothermal aging on the damage mechanisms of short white Hemp Fiber Reinforced Polypropylene (HFRP) composites with various fiber contents (10, 20, 30, and 40 wt%). Injected molded specimens were subjected to hygrothermal aging with a relative humidity of 80% and two temperatures, 25 and 50°C. The water absorption and its effect on tensile properties of HFRP composites were investigated. The Acoustic Emission (AE) technique combined with scanning electron microscopy observations was used to identify microstructural damage events leading to overall failure of the HFRP composites. This identification according to hemp‐fiber content and hygrothermal aging was made with an unsupervised method based on a statistical multi‐variable analysis (k‐means algorithm). The AE results indicate that the quality of fiber‐matrix interface plays a major role in the damage process of HFRP composites, shown by the number of AE signals induced by the interface failure and their amplitude ranges. POLYM. COMPOS. 37:1101–1112, 2016. © 2014 Society of Plastics Engineers 相似文献
95.
Mohammad Ali Najafi Karamatollah Rezaei Mohammad Safari Seyyed Hadi Razavi 《Food science and biotechnology》2012,21(1):51-57
In this study, effects of 8 different sourdough starters prepared with Saccharomyces cerevisiae, Lactobacillus plantarum, L. acidophilus, and Leuconostoc mesenteroides were investigated on the phytic acid level and mole ratio of phytic acid to zinc in a traditional Iranian bread (sangak). Different sourdough preparations were made and incubated at 30°C for 16 h and added to the dough at 10, 20, and 30% replacement
levels. Use of sourdough resulted in a decrease in phytic acid level (also in a decrease in the phytic acid to zinc mole ratio)
and corresponding increase in zinc bioavailability index when compared to the commercial sangak bread. The lowest phytic acid concentration and highest zinc bioavailability index were achieved when S. cerevisiae, L. plantarum, and Leu. mesenteroides were used at 30.0% dough replacement with sourdough. This study provides awareness about the negative impacts of higher phytic
acid level in the breads, which is particularly the case for sangak bread, and also provides a solution for such issue. 相似文献
96.
M. Hadi Amoozgar Abbas Chamseddine Youmin Zhang 《Journal of Intelligent and Robotic Systems》2013,70(1-4):107-117
This paper addresses the problem of Faut Detection and Diagnosis (FDD) of a quadrotor helicopter system in the presence of actuator faults. To this end a Two-Stage Kalman Filter (TSKF) is used to simultaneously estimate and isolate possible faults in each actuator. The faults are modelled as losses in control effectiveness of rotors. Three fault scenarios are investigated: loss of control effectiveness in one single actuator, simultaneous loss of control effectiveness in all motors, and loss of control effectiveness in three motors with different magnitudes. The developed FDD algorithm is evaluated through experimental application to an unmanned quadrotor helicopter testbed available at the Department of Mechanical and Industrial Engineering of Concordia University, called Qball-X4. The obtained results show the effectiveness of the proposed FDD method. 相似文献
97.
Dai Yue Rasekh Maryam Eslami Mirfarshbafan Seyed Hadi Liew Harrison Gallyas-Sanhueza Alexandra Dunn James Madhow Upamanyu Studer Christoph Nikolić Borivoje 《Journal of Signal Processing Systems》2022,94(10):989-1003
Journal of Signal Processing Systems - This paper presents an algorithm-adaptable, scalable, and platform-portable generator for massive multiple-input multiple-output (MIMO) baseband processing... 相似文献
98.
Zarandi Mostafa Poursoltani Beitollahi Hadi 《Journal of Materials Science: Materials in Electronics》2022,33(25):19723-19733
Journal of Materials Science: Materials in Electronics - In present work, a novel and facile electrode was constructed using the modification of carbon paste electrode (CPE) with N-doped reduced... 相似文献
99.
Mostafa Noohi Ali Mirvakili Hadi Safdarkhani Sayed Alireza Sadrossadat 《ETRI Journal》2023,45(3):519-533
This paper implements a simultaneous solar and thermal energy harvesting system, as a hybrid energy harvesting (HEH) system, to convert ambient light into electrical energy through photovoltaic (PV) cells and heat absorbed in the body of PV cells. Indeed, a solar panel equipped with serially connected thermoelectric generators not only converts the incoming light into electricity but also takes advantage of heat emanating from the light. In a conventional HEH system, the diode block is used to provide the path for the input source with the highest value. In this scheme, at each time, only one source can be handled to generate its output, while other sources are blocked. To handle this challenge of combining resources in HEH systems, this paper proposes a method for collecting all incoming energies and conveying its summation to the load via the current mirror cells in an approach similar to the maximum power point tracking. This technique is implemented using off-the-shelf components. The measurement results show that the proposed method is a realistic approach for supplying electrical energy to wireless sensor nodes and low-power electronics. 相似文献
100.
This paper aims to assess the applicability of the bonded–interface technique (BIT) that has been used for examining sub-surface damage in brittle materials. With the aid of the finite element method, the indentation stress fields in alumina specimens with and without a bonded–interface were analysed. It was found that the bonded–interface greatly alters the stress distribution in the neighbourhood of the interface. The high-stress zone shifts away from the interface, and extends to the surface. Both glue layer mechanical properties and bond thickness play a limited role in the overall stress field of the BIT alumina. Comparisons of theoretical predictions with experimental observations showed that, to a great extent, the BIT presents a different pattern of sub-surface damage. The study clarifies the applicability of the BIT and offers a useful guideline for practitioners. 相似文献