全文获取类型
收费全文 | 557篇 |
免费 | 35篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 6篇 |
综合类 | 1篇 |
化学工业 | 131篇 |
金属工艺 | 27篇 |
机械仪表 | 21篇 |
建筑科学 | 26篇 |
矿业工程 | 2篇 |
能源动力 | 23篇 |
轻工业 | 65篇 |
石油天然气 | 4篇 |
无线电 | 49篇 |
一般工业技术 | 112篇 |
冶金工业 | 64篇 |
原子能技术 | 3篇 |
自动化技术 | 59篇 |
出版年
2024年 | 3篇 |
2023年 | 7篇 |
2022年 | 14篇 |
2021年 | 16篇 |
2020年 | 24篇 |
2019年 | 22篇 |
2018年 | 28篇 |
2017年 | 17篇 |
2016年 | 30篇 |
2015年 | 19篇 |
2014年 | 28篇 |
2013年 | 70篇 |
2012年 | 31篇 |
2011年 | 64篇 |
2010年 | 31篇 |
2009年 | 26篇 |
2008年 | 27篇 |
2007年 | 21篇 |
2006年 | 17篇 |
2005年 | 15篇 |
2004年 | 12篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有593条查询结果,搜索用时 31 毫秒
101.
Collie Alexander; Maruff Paul; Yucel Murat; Danckert James; Currie Jon 《Canadian Metallurgical Quarterly》2000,26(6):1733
Currently, there is debate regarding both the spatial and temporal relationship between facilitation and inhibition of return (IOR) components of attention, as observed on the covert orienting of visual attention task (COVAT). These issues were addressed in a series of experiments where the spatial and temporal relationships between cue and target were manipulated. Facilitation occurred only when the stimulus onset asynchrony (SOA) was short and there was temporal overlap between cue and target. IOR occurred only when SOA was long and there was no temporal overlap between cue and target. Facilitation encompassed the cued location and all locations between the cue and fixation, whereas IOR arose for the entire cued hemifield. These findings suggest that the facilitation and IOR found on COVATs that use noninformative peripheral cues are separable and stimulus-driven processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
102.
Yucel Birol 《国际钢铁研究》2009,80(8):588-592
Semisolid processing, already a well established manufacturing route for the production of intricate, thin‐walled aluminium and magnesium parts with mechanical properties as good as forged grades, faces a major challenge in the case of steels. The tool materials must withstand complex load profiles and relatively higher forming temperatures for thousands of forming cycles for industrial application to be attractive. Since the forming pressures are much lower than those encountered in conventional forging, the principle die failure mechanism in steel thixoforging is expected to be thermal fatigue. Hence, suitable materials able to withstand the steel thixoforming environment for an economically acceptable life, can be best identified with a thermal fatigue test. Such a test is described in the present work. A novel CrNiCo and a nickel‐base superalloy, reported to exhibit superior thermal fatigue resistance in demanding tooling applications, was tested under thermal fatigue conditions encountered in the thixoforming of steels. 相似文献
103.
Hakan A. Cirpan Yucel Turker Erdinc Cekli 《AEUE-International Journal of Electronics and Communications》2001,55(2):119-122
A stochastic maximum likelihood approach for blind estimation of co-channel signals received at an antenna array is proposed in this letter. A hidden Markov model formulation of the problem is introduced and the Baum-Welch algorithm for the associated stochastic maximum likelihood estimation procedure is modified. The performance of the proposed algorithm based on the evaluation of approximate Cramer-Rao bounds is studied. Finally, some simulation results are presented. 相似文献
104.
Serpil Ünver Saraydin Dursun Saraydin Zeynep Deniz ahin nan 《Microscopy research and technique》2020,83(4):436-445
Nowadays, apoptosis is mostly evaluated visually in histological studies. By using the quantitative digital image analysis, this study aimed to investigate the effect of acrylamide‐based monomers (acrylamide [AAm], methacrylamide [MAAm], N‐isopropylacrylamide [NIPAm]) on the cerebrum tissues in rats, which are the most common water‐soluble monomers in the production of polymeric hydrogels used as biomaterials. The Wistar albino rats weighing ~220–240 g were divided into control and three test groups. The control group received 1 mL of saline, and the test groups received 1 mL of aqueous 50 mg/kg/day intramuscular injection of AAm, MAAm, and NIPAm, respectively. At the end of the experiments, brain tissues of all rats euthanized by intramuscular injection of sodium pentobarbital were removed. Terminal deoxynucleotide transferase dUTP nick and labeling (TUNEL) method was applied to brain tissue sections. The monomers have been shown to cause apoptosis due to oxidative stress in cerebrum tissue. Based on apoptosis by tunneling method, quantitative digital image analysis of cell fragments was performed with Olympus cellSens Dimension 1.15 software, and the number, total count area, selected area, average area, and ROI% values of the fragments were found. In addition, the total area and ROI% values of the fragments increased linearly with increasing the molar mass of monomers from the digital image analysis data. Quantitative digital image analysis can facilitate the monitoring of apoptosis caused by the oxidative stress of monomers used in the production of the biomaterials. 相似文献
105.
Servet Birgin Iritas Vugar Ali Turksoy Serdar Deniz Serhat Kocoglu Gullu Kirat Ali Can Demirkesen Alper Baba 《Water and Environment Journal》2019,33(4):518-535
Public fountains are very common and everyday people appreciate the benefits a water fountain can bring. However, consumption of public fountain water in some country has decreased because of growing concerns that constituents in fountain water may have adverse effects on health. A few studies have examined the safety of public fountains, proposing only limited evidence of fountain‐related health issues in Turkey. Most of these public fountains are sourced from natural springs in Turkey. In this study, a 177 fountain water and 32 rock samples were analysed for source and quality of water. The geology of the region has the direct impact on the quality of the public fountain water. The results indicate that the level of some elements exceeded the limit values determined by WHO and US.EPA. The most striking high values were observed for iron (Fe), nickel (Ni), aluminum (Al), arsenic (As) and bromine (Br) concentrations. 相似文献
106.
Han Mo Günay Sezen Yağmur Schirner Gunar Padır Taşkın Erdoğmuş Deniz 《Intelligent Service Robotics》2020,13(1):179-185
Intelligent Service Robotics - Upper limb and hand functionality is critical to many activities of daily living, and the amputation of one can lead to significant functionality loss for... 相似文献
107.
ABSTRACTThe present study aimed to evaluate the antimicrobial effect of gaseous ozone against specific oral pathogens on denture base resins. 1080 round samples were prepared (10mm-diameter, 2mm-thickness). Candida albicans, Streptococcus mutans, Streptococcus gordonii, and Aggregatibacter actinomycetemcomitans, polyamide-Deflex, heat-cured polymethyl-methacrylate (PMMA)-QC-20, and cold-cured-PMMA-Meliodent. The doses and durations: 25, 50 and 100µg/ml, 5, 10, 20, 30 minutes. For Cell viability (CV) MTT was used. 100µg/ml was most effective dose for C. albicans, S .gordonii, and A. actinomycetemcomitans were in heat-cured-PMMA and polyamide for S.mutans. For polyamide, lowest CV was 43% in S.mutans and A.actinomycetemcomitans. CV of heat-cure and cold-cure PMMA were 31% and 32% in S.gordonii, respectively. CV was similar for all resins and durations in S.mutans and A.actinomycetemcomitans and for polyamide for C.albicans and for heat-cure PMMA for S.gordonii. 30-min ozone application killed 80% of all microorganisms in all resins except for C.albicans in polyamide (65% cell death) and cold-cure PMMA (57% cell death). Optimal dose/duration combination was 100 µg/ml-10 min. Gaseous ozone can be considered as an effective cleansing agent for denture base resins. 相似文献
108.
Retroperitoneal perforation of duodenal ulcer is a rare condition. Diagnostic difficulties lead to high mortality. Two cases are presented in this report. 相似文献
109.
OBJECTIVE: We compared our ability to make iliac artery measurements on two-dimensional (2D) time-of-flight (TOF) and three-dimensional dynamic gadolinium-enhanced MR angiography with conventional angiography. SUBJECTS AND METHODS: Fifteen patients with lower extremity vascular disease underwent pelvic MR angiography. Parameters of the cardiac-gated axial 2D TOF sequence included a TR/TE of 24/7 msec and a 50 degrees flip angle. Parameters for the three-dimensional MR angiography sequence, in which we obtained 32 coronal 3-mm slices with fat suppression, included a TR/TE of 32/5 msec and a 40 degrees flip angle during infusion of 40 ml of gadolinium-chelated contrast material. Patients then underwent conventional angiography of the iliac arteries. Maximum stenosis in the common iliac, external iliac, and common femoral arteries was then measured. Measurements of stenosis were compared by repeated measures of analysis of variance. Sensitivity and specificity were calculated for identification of greater than or equal to 50% stenosis and less than 50% stenosis. RESULTS: For all vessels studied, we found no significant difference in measurements obtained from the gadolinium-enhanced MR angiography technique and those obtained from conventional angiography (p > .05). However, significantly different stenotic measurements were obtained from the 2D TOF MR angiography sequence and conventional angiography. In the external iliac arteries, 2D TOF MR angiography exaggerated stenoses most substantially. Gadolinium-enhanced MR angiography achieved 100% sensitivity and specificity. CONCLUSION: Dynamic gadolinium-enhanced MR angiography was more accurate than 2D TOF MR angiography when measuring degree of stenosis in the iliac arteries. 相似文献
110.
A method for designing a terrestrial digital audio broadcasting single frequency network (T-DAB SFN) for a mountainous region is proposed. A computer database and the digital terrain elevation data are used in designing the network. Two fundamental approaches are compared; first, utilization of the existing transmitter sites is maximized by applying the initial cost constraint; then, the coverage percent of the service is forced to approach to 100% by applying the coverage efficiency constraint. Finally, a T-DAB SFN hybrid design procedure optimizing both constraints is proposed. The three design approaches are illustrated on the coverage of the mountainous Istanbul-Ankara highway. The results are compared using a reference cost look up table. The hybrid approach is shown to optimize the initial cost and the coverage efficiency, and can be applied to similar networking problems 相似文献