全文获取类型
收费全文 | 770篇 |
免费 | 31篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 51篇 |
综合类 | 1篇 |
化学工业 | 154篇 |
金属工艺 | 29篇 |
机械仪表 | 16篇 |
建筑科学 | 23篇 |
能源动力 | 18篇 |
轻工业 | 65篇 |
水利工程 | 5篇 |
无线电 | 55篇 |
一般工业技术 | 115篇 |
冶金工业 | 172篇 |
原子能技术 | 25篇 |
自动化技术 | 79篇 |
出版年
2023年 | 2篇 |
2022年 | 10篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 20篇 |
2017年 | 8篇 |
2016年 | 24篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 34篇 |
2012年 | 26篇 |
2011年 | 44篇 |
2010年 | 28篇 |
2009年 | 31篇 |
2008年 | 27篇 |
2007年 | 21篇 |
2006年 | 25篇 |
2005年 | 33篇 |
2004年 | 20篇 |
2003年 | 30篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 14篇 |
1999年 | 24篇 |
1998年 | 67篇 |
1997年 | 55篇 |
1996年 | 29篇 |
1995年 | 13篇 |
1994年 | 16篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 11篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1969年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有808条查询结果,搜索用时 31 毫秒
51.
The infrared chemiluminescence spectra of CO2 formed during steady-state CO+NO reaction over Pd(110) indicated that the temperature of the bending vibrational mode was much higher than that of the antisymmetric one at higher surface temperatures such as 800–850 K. Especially, in the high temperature range, more vibrationally excited CO2 was formed from CO+NO reaction than CO+O2 reaction. On the basis of the result, we propose the model structure of reaction intermediates for CO2 formation in CO+NO reaction, which is different from that in CO+O2 reaction. 相似文献
52.
Electrolytic removal of ammonia from brine wastewater: scale‐up,operation and pilot‐scale evaluation
Catalino G Alfafara Takayuki Kawamori Nakao Nomura Masayuki Kiuchi Masatoshi Matsumura 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(3):291-298
Brine wastewater with a high ammonia content from an iodine processing plant (commonly called kansui in Japan) was treated by electrolysis. The system, which can be considered as an indirect electrolytic treatment process, generates chlorine at the anodes and initiates the formation of mixed oxidants like hypochlorous acid. The oxidants then act as agents for ammonia destruction. Laboratory‐scale experiments showed that high ammonia concentrations (as much as 200 mg dm?3) could be completely removed within a few minutes, and could be considered a good alternative for efficient ammonia removal from saline wastewaters. From laboratory‐scale experiments in the batch and continuous modes, the charge dose was analyzed and used as the operating and scale‐up factor. The value of the charge dose was not severely affected by changes in operating conditions such as electrode spacing and temperature. The charge dose from batch and continuous runs was found to be in the range of 23 C (mg NH4‐N removed)?1 to 29 C (mg NH4‐N removed)?1. Using the charge dose obtained from laboratory‐scale continuous electrolysis experiments as the scale‐up factor, a pilot‐scale reactor was designed, and the operating conditions were calculated. In the pilot‐scale reactor tests at different flow rates, the effluent ammonia concentrations were reasonably close to the calculated values predicted from the charge dose equation. Copyright © 2004 Society of Chemical Industry 相似文献
53.
54.
The contribution ratio of indoor climate (CRI) derived from computational fluid dynamics (CFD) was developed to estimate the
individual contribution of heat factors to any location inside a room. The CRI index indicates the structure of the temperature
field and allows the CFD results to be applied to analysis and design, with more efficient application. In this study, the
concept and calculation method for CRI is introduced first. As an example of the application of CRI, a method for predicting
temperatures at any point in a room with a small number of temperature sensors based on CRI is developed. The accuracy of
the method is examined by comparing the prediction with a coupled simulation of CFD and radiation. 相似文献
55.
The physiological effects of hydroxypropyl‐distarch phosphate (HDP) were examined in rats. Male rats were fed a fiber‐free purified diet containing gelatinized potato starch (PS, 50 g/kg diet) that was not modified chemically or gelatinized, chemically modified potato starch (CMS, 50 g/kg diet) for 21 d. PS was used as the control. Six kinds of gelatinized HDP from potato with 2 different degrees of hydroxypropylation and 3 different degrees of cross‐linking were used as CMS. The wet weight and moisture of the fecal output of the rats fed highly hydroxypropylated HDP was 70% and 30% greater, respectively, than that in the control rats. The weights of the cecal wall and content of the rats fed highly hydroxypropylated HDP were 15% and 30% higher, respectively, than those of the control rats. The apparent absorption of Mg was 15% higher in the rats fed highly hydroxypropylated HDP than in the control rats. On the other hand, the apparent absorptions of Ca, Zn, and Fe were not affected by the diet. Cross‐linking did not influence the above‐mentioned physiological effects of HDP. Fecal excretion of bile acids and the plasma cholesterol concentration were not affected by the diet. These results show that the physiological effects of HDP depend on the hydroxypropylation but not the cross‐linking. 相似文献
56.
Sugimoto K Nomura K Nishimura T Kiso T Sugimoto K Kuriki T 《Journal of Bioscience and Bioengineering》2005,99(3):272-276
Alpha-arbutin is a tyrosinase inhibitor. We synthesized alpha-arbutin-alpha-glycosides by the transglycosylation reaction of cyclomaltodextrin glucanotransferase from Bacillus macerans using alpha-arbutin and starch as acceptor and donor molecules, respectively. We isolated and characterized two major products from the reaction mixture. The structural analyses using 13C- and 1H-NMR spectroscopy proved that they were 4-hydroxyphenyl alpha-maltoside (alpha-Ab-alpha-G1) and 4-hydroxyphenyl alpha-maltotrioside (alpha-Ab-alpha-G2). Both alpha-Ab-alpha-G1 and alpha-Ab-alpha-G2 exhibited competitive-type inhibition on human tyrosinase as alpha-arbutin does. Their K(i) values were calculated to be 0.6 mM and 2.8 mM, respectively, which is slightly and significantly higher than that of alpha-arbutin (0.2 mM). 相似文献
57.
An adaptive control optimization system was developed to produce a desired surface finish roughness by automatic control of the work-piece feed-rate in circular sawing. The system developed in this study consists of the interconnection of an adaptive controller with a numerically controlled circular saw. The AE signals and cutting forces were measured to monitor the machining process continuously in this system. The signals were provided to the adaptive controller to evaluate the surface finish roughness and adjust the workpiece feed-rate automatically in the machining process. Sensing of AE signals and of cutting forces was compared to determine which technique is more convenient. Experiments were carried out with a carbide-tipped circular saw. Cross cutting was done with counter-cutting during the experiments. The cutting parameters controlled were workpiece feed-rates and cutting speeds. Japanese beech (Fagus crenata Blume) and Yezo spruce (Picea jezoensis Carr.) were used as the workpiece. Experimental results indicated that adaptive control optimization took place in the system developed for circular sawing. The desired surface finish roughness was produced by automatic control of the workpiece feed-rate using the sensing technique of AE signals as well as that of cutting force. However, the system using AE signals is more convenient than taht using cutting force. 相似文献
58.
Ryota Kato Yasunari Yoshitomi Taro Asada Masayoshi Tabuse 《Artificial Life and Robotics》2010,15(1):10-16
The purpose of this study was to develop a system for communication between a human and a computer generated (CG) character
to make him or her more peaceful and cheerful. Nonverbal communication using such things as facial expression, a nod, or a
hand gesture is very important for reciprocal communication between humans. In this study, an image registered by infrared
rays which describes the thermal distribution of the face and neck has been used to develop a system for communication between
a human and a CG character. The CG character can synchronize its nod with a person’s nod by predicting his or her nod angle.
The measured feature parameter is input to a fuzzy algorithm system to obtain the nod angle of a person in front of an infrared
camera, and then a moving-average model is used to predict the nod angle of the person. The average error of the nod angle
obtained by the system has been estimated as about 5°. The CG character nods its head, not only when the human nods his or
her head, but also when the human shakes his or her head to the left or right. 相似文献
59.
Taro Ueki 《Annals of Nuclear Energy》2011,38(11):2462-2469
Batch methodology is among the techniques for computing the standard deviation of sample mean and is applicable to any output series from stationary iteration cycles. In the present article, three forms of the methodology are investigated: non-overlapping batch means (NBM), which dates back to Conway (1963), overlapping batch means (OBM) by Meketon and Schmeiser (1984), and standardized time series (STS) by Schruben (1983). In particular, they are applied to the MC calculation of local powers of a pressurized water reactor. The numerical results reveal that the performance of NBM is equivalent to that of OBM, whereas STS performs poorly for small batch sizes. It is also shown that OBM can be improved based on the method of autocovariance bias correction. For a computational condition leading to 0.5–1.5% statistical errors, the improved OBM for a batch size of 10% of the stationary iteration cycle length yields 88–103% of the reference value of standard deviation at tally cells where the sample standard deviation yields 22–36% of the same reference value. 相似文献
60.
Cicilia Maria Erna Susanti Tetsuya Nakao Hiroshi Yoshihara 《Engineering Fracture Mechanics》2011,78(16):2775-2788
Asymmetric four-point bending tests of agathis specimens with a short crack along the neutral axis in a tangential–longitudinal system were conducted onto analyse the failure behaviour of wood with a short crack. The nominal shear strength and Mode II critical stress intensity factors of the specimens with various crack lengths were measured, and the influence of crack length on these properties was examined. The nominal shear strength of the cracked specimens was significantly lower than the strength of a crack-free specimen, even when the crack was extremely short. This finding suggests that the fracture mechanics theory is effective for analysing the failure behaviour of wood with a very short crack in this loading condition. However, the Mode II critical stress intensity factor still depends on the crack length. When the crack length was corrected with considering the formation of fracture process zone ahead of the crack tip, the critical intensity factor could be predicted effectively as well as the nominal shear strength. 相似文献