全文获取类型
收费全文 | 1411篇 |
免费 | 84篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 32篇 |
综合类 | 6篇 |
化学工业 | 501篇 |
金属工艺 | 51篇 |
机械仪表 | 40篇 |
建筑科学 | 46篇 |
矿业工程 | 11篇 |
能源动力 | 41篇 |
轻工业 | 112篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 118篇 |
一般工业技术 | 210篇 |
冶金工业 | 40篇 |
原子能技术 | 7篇 |
自动化技术 | 281篇 |
出版年
2024年 | 2篇 |
2023年 | 13篇 |
2022年 | 72篇 |
2021年 | 103篇 |
2020年 | 49篇 |
2019年 | 42篇 |
2018年 | 42篇 |
2017年 | 49篇 |
2016年 | 77篇 |
2015年 | 56篇 |
2014年 | 88篇 |
2013年 | 128篇 |
2012年 | 96篇 |
2011年 | 81篇 |
2010年 | 63篇 |
2009年 | 69篇 |
2008年 | 79篇 |
2007年 | 53篇 |
2006年 | 42篇 |
2005年 | 33篇 |
2004年 | 38篇 |
2003年 | 36篇 |
2002年 | 23篇 |
2001年 | 13篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 11篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 1篇 |
1981年 | 8篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1969年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1501条查询结果,搜索用时 0 毫秒
61.
Tianwu Wang Krzysztof Iwaszczuk Emil Astrup Wrisberg Emil Vosmar Denning Peter Uhd Jepsen 《Journal of Infrared, Millimeter and Terahertz Waves》2016,37(6):592-604
The performance of air-biased coherent detection (ABCD) in a broadband two-color laser-induced air plasma system for terahertz time-domain spectroscopy (THz-TDS) has been investigated. Fundamental parameters of the ABCD detection, including signal-to-noise ratio (SNR), dynamic range (DR), and linearity of detection have been characterized. Moreover, the performance of a photomultiplier tube (PMT) and an avalanche photodiode (APD) as photodetector in the ABCD have been compared. We have observed nonlinear behavior of PMT detector, which leads to artificial gain factor in TDS spectroscopy. The APD turns out to have superior linearity and three times higher dynamic compared to the PMT. 相似文献
62.
63.
Ewa Watorek Tomasz Golebiowski Mariusz Kusztal Krzysztof Letachowicz Waldemar Letachowicz Hanna Augustyniak Bartosik Jerzy Garcarek Katarzyna Madziarska Wacław Weyde Marian Klinger 《Hemodialysis international. International Symposium on Home Hemodialysis》2014,18(1):113-117
Elderly patients, defined as octogenarians and nonagenarians, are an increasing population entering renal replacement therapy. Advanced age appears as an exclusive factor negatively influencing dialysis practice. Elderly patients are referred late for the initiation of hemodialysis and more likely are offered catheters rather than arteriovenous fistulae (AVF), which increase mortality and negatively affect quality of life. We present our approach to the creation of vascular access for hemodialysis in this demanding population. In 2006–2012, 39 patients aged 85.9 ± 2.05 with end‐stage renal disease, mainly resulting from ischemic nephropathy, were admitted to the Department of Nephrology to establish permanent vascular access for hemodialysis: preferably AVF. Temporary dialysis catheters were implanted in uremic emergency to bridge the time to fistula creation/maturation. AVF was attempted in 87.2% of the patients. Primary AVF function was achieved in 54% of the patients. Cumulative proportional survival of AVF at months 12 and 24 was 81.5%. Ninety‐four percent of AVF were localized on the forearm: 74% in the distal and 20% in the proximal part. Mean duration of hemodialysis therapy was 20.80 ± 19.45 months. The mean time of AVF use was 15.9 ± 20.2 months. Until present, 38% have been dialyzed using AVF for 31.0 ± 18.8 months. Five patients died with functioning fistula. Eight patients initiated hemodialysis therapy with fistula. During further observation, the use of AVF increased to 62%. Elderly patients should not be denied creation of AVF as a rule. The outcome of AVF benefits more from acknowledging individual vascular conditions rather than age of the patient. 相似文献
64.
65.
The article presents results of electrodeposition of Co-Mo Co-Mo-C alloys in a magnetic field characterized by low overvoltage of hydrogen evolution.Addition of molybdenum and carbon was to lower the values of overvoltage of hydrogen evolution on cobalt.The influence of bath pH,bath composite,current density and magnetic field with different orientation on the deposits composition,structure and overpotential for hydrogen evolution reaction(HER)was determined.Electrocatalytic properties of the obtained alloy coatings within the range of hydrogen evolution were tested in a concentrated NaOH solution.The comparison of electrocatalytic properties of Co-Mo alloys with properties of Co-Mo-C ones enabled determining the influence of carbon presence in cathodic deposits on the overpotential values for hydrogen evolution. 相似文献
66.
Krzysztof Buksa Anna NowotnaRafa? Ziobro Halina Gambu?Stanis?aw Kowalski 《Food Hydrocolloids》2012,27(1):72-79
The main constituents of rye flour extracts are proteins and pentosans. After cross-linking under the action of oxidizing agents those components are able to bind much more water than in their native (prior to modifications) state. As a consequence rheological properties of extract are changed.It was observed that kinematic viscosity of water extract of rye flour decreases rapidly with time. The reason for this behavior could be high enzymatic activity of flour extract.It was also found that the addition of hydrogen peroxide in the absence of additional peroxidase (which is naturally present in 1:9 or 1:1 water extracts of flour) causes the greatest increase in viscosity, due to the cross-linking of soluble polymers. Moreover after the addition of H2O2 to water extracts strong gels were obtained, which were characterized by tan δ = 0.5 (tan δ < 1). Moreover G′ was independent of frequency, which also suggests cross-linking of the pentosans.The addition of ascorbic acid, which is known to act preferably on gluten proteins, to 1:9 or 1:1 flour extracts had only a little effect on viscosity. In this case the values of tan δ = 0.9 were close to 1, which is typical for a weak gel.The application of inactivated rye flour extract, containing mainly proteins and pentosans, proved stronger effect of H2O2 in comparison to ascorbic acid on polymer cross-linking, but only after the addition of peroxidase. The gel obtained with H2O2 and peroxidase was also characterized by low tan δ = 0.4.The results indicate, that pentosans are the main subject of cross-linking reactions in rye flour water extracts. 相似文献
67.
The paper presents a new form of the electrothermal model of the ferromagnetic core for SPICE and the way, in which the parameters of the model are determined. The manner of determining magnetic, geometric and thermal parameters of this model is described. The correctness of the proposed model and the manner of determining the values of the parameters are verified by comparing the calculated and measured characteristics of the selected ferromagnetic cores. 相似文献
68.
Grain boundary distributions in the space of macroscopic boundary parameters are basic statistical characteristics of boundary networks. To avoid artifacts caused by the currently used computation method, it is proposed to utilize the kernel density estimation technique and to determine boundary distributions based on metric functions defined in the boundary space. A distribution is calculated at points of interest by summing areas of boundaries that fall within specified distances from these points. The new method is illustrated on experimental data of a nickel-based superalloy. 相似文献
69.
70.
Michał Chojnacki Stanisław Jóźwiak Krzysztof Karczewski Zbigniew Bojar 《Intermetallics》2011,19(10):1555-1562
An attempt to modify sintering of iron and aluminium elemental powders with use of small additions of Mg and MgH2 was presented in this paper. The kinetics of such modified sintering was investigated using DSC technique, XRD analysis and SEM observations. Significant changes in the mechanism of exothermal formation reaction of Fe–Al intermetallic phases in compositions doped with magnesium and its hydride was observed. Initiation temperature of Self-propagating High-temperature Synthesis (SHS) reaction was pronouncedly shifted to lower value as compared with undoped composition. Influence of additions on the SHS reaction kinetics parameters was also calculated with use of the JMA model and changes of the Avrami exponent value of specific phase formation was noticed. Positive effect of MgH2 addition on partial homogeneity of final product was also studied. 相似文献