首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   148篇
  免费   13篇
电工技术   12篇
化学工业   42篇
金属工艺   9篇
机械仪表   10篇
建筑科学   3篇
能源动力   6篇
轻工业   21篇
无线电   9篇
一般工业技术   24篇
冶金工业   8篇
原子能技术   3篇
自动化技术   14篇
  2022年   1篇
  2021年   2篇
  2020年   3篇
  2019年   1篇
  2018年   5篇
  2017年   4篇
  2016年   4篇
  2015年   5篇
  2014年   8篇
  2013年   8篇
  2012年   9篇
  2011年   7篇
  2010年   8篇
  2009年   10篇
  2008年   1篇
  2007年   4篇
  2006年   6篇
  2005年   10篇
  2004年   4篇
  2003年   8篇
  2002年   4篇
  2001年   1篇
  2000年   4篇
  1999年   3篇
  1998年   2篇
  1997年   6篇
  1996年   2篇
  1995年   1篇
  1994年   5篇
  1993年   1篇
  1992年   5篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1983年   3篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1974年   1篇
排序方式: 共有161条查询结果,搜索用时 15 毫秒
1.
Thromboembolism has been shown to play a role in the pathogenesis of inflammatory bowel disease (IBD). A possibility exists that lipoprotein (a) [Lp(a)], a newly-discovered prothrombotic factor, also participates in the development of at least some cases of IBD. Marked elevation of serum Lp(a) levels was observed in a young patient with ulcerative colitis. A biopsy specimen of the rectal mucosa showed findings compatible with ulcerative colitis, as well as small vessel thrombus occurring within the muscularis mucosa in the rectum. Serum Lp(a) levels were markedly elevated on admission (71 mg/dl), with a gradual decrease to 46 mg/dl on discharge. Moreover, serum Lp(a) levels decreased in parallel with clinical improvement. In the quiescent clinical stage, no small vessel thrombus was observed in the mucosa on follow-up colonoscopy. The association between IBD and hyper-Lp(a)-emia would be presumable but it has been, to our knowledge, previously unreported. The case reported here would be the first young patient, suggesting the presence of hyper-Lp(a)-emia and small vessel thrombus formation occurring in association with the development of ulcerative colitis.  相似文献   
2.
In negation-limited complexity, one considers circuits with a limited number of NOT gates, being motivated by the gap in our understanding of monotone versus general circuit complexity, and hoping to better understand the power of NOT gates. We give improved lower bounds for the size (the number of AND/OR/NOT) of negation-limited circuits computing Parity and for the size of negation-limited inverters. An inverter is a circuit with inputs x 1,…,x n and outputs ¬ x 1,…,¬ x n . We show that: (a) for n=2 r ?1, circuits computing Parity with r?1 NOT gates have size at least 6n?log?2(n+1)?O(1), and (b) for n=2 r ?1, inverters with r NOT gates have size at least 8n?log?2(n+1)?O(1). We derive our bounds above by considering the minimum size of a circuit with at most r NOT gates that computes Parity for sorted inputs x 1???x n . For an arbitrary r, we completely determine the minimum size. It is 2n?r?2 for odd n and 2n?r?1 for even n for ?log?2(n+1)??1≤rn/2, and it is ?3n/2??1 for rn/2. We also determine the minimum size of an inverter for sorted inputs with at most r NOT gates. It is 4n?3r for ?log?2(n+1)?≤rn. In particular, the negation-limited inverter for sorted inputs due to Fischer, which is a core component in all the known constructions of negation-limited inverters, is shown to have the minimum possible size. Our fairly simple lower bound proofs use gate elimination arguments in a somewhat novel way.  相似文献   
3.
We have carried out the optical observation, electrical conductivity and 205Tl NMR measurements, and subsequently investigated the origin of the large conductivity above ferroelastic phase transition temperature Tc (=661 K) on the basis of the domain structure and the crystal structure. Electrical conductivity exhibits the discontinuous increase around Tc with increasing temperature and becomes approximately 5 × 10−3 S m−1 above Tc. Moreover, from the 205Tl NMR measurements, it is found that mobile Tl ions exist above Tc. Furthermore, from the analysis of the domain structure based on the crystal structure in the low-temperature ferroelastic phase, it is also found that the anomalously large fluctuations of SeO4 tetrahedrons exist above Tc. It is deduced from these results that the high electrical conductivity above Tc is caused by the mobile Tl ions closely related to the anomalously large fluctuations of SeO4 tetrahedrons accompanied by the ferroelastic phase transition.  相似文献   
4.
Currently, the development of leading‐edge technology for recording and loading human motion on the basis of haptic information is required in the fields of manufacturing and human support. Human movement is an assembly of motion components. Since human movements should be supported by a robot in real time, it is necessary to integrate the motion components that were saved earlier. Once such motion integration is realized, future technology for use in daily human life can be developed. This paper proposes the integrated reproduction of the decomposed components of human motion by using a motion copying system. This system is the key technology for the realization of the acquisition, saving, and reproduction of real‐world haptic information. By using the proposed method, it is possible not only to achieve expert skill acquisition, skill transfer to robots, and power assist for each motion component, but also to open up new areas of applications. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(1): 28–35, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21263  相似文献   
5.
6.
Kurihara M  Ikeda K  Izawa Y  Deguchi Y  Tarui H 《Applied optics》2003,42(30):6159-6165
A laser-induced breakdown spectroscopy (LIBS) technique has been applied for detection of unburned carbon in fly ash, and an automated LIBS unit has been developed and applied in a 1000-MW pulverized-coal-fired power plant for real-time measurement, specifically of unburned carbon in fly ash. Good agreement was found between measurement results from the LIBS method and those from the conventional method (Japanese Industrial Standard 8815), with a standard deviation of 0.27%. This result confirms that the measurement of unburned carbon in fly ash by use of LIBS is sufficiently accurate for boiler control. Measurements taken by this apparatus were also integrated into a boiler-control system with the objective of achieving optimal and stable combustion. By control of the rotating speed of a mill rotary separator relative to measured unburned-carbon content, it has been demonstrated that boiler control is possible in an optimized manner by use of the value of the unburned-carbon content of fly ash.  相似文献   
7.
In industry, temperature control and heat flow control are now applied in many thermal devices, including Peltier devices, which facilitates heat transfer by the Peltier effect. Generally, temperature control compensates for heat flowing from the external environment, while heat actively flows into the system during heat flow control. Thus, temperature control and heat flow control differ from each other. However, there have been no detailed discussions of a thermal control process in which the thermal conductance control ranges between 0 and . This paper focuses on thermal conductance control and the construction of a thermal conductance control system for a Peltier device using a heat disturbance observer. When using the thermal conductance controller, the thermal conductance control is altered and the system becomes thermally compliant with the external environment. This paper also presents experimental results that confirm the validity of the proposed control system. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 185(4): 44–52, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22411  相似文献   
8.
The damage caused by an earthquake-induced landslide can generally be classified as either a limited deformation or a catastrophic failure. From an engineering point of view, the latter can be much more dangerous because the sliding mass may continue moving until it collides with another object. If a catastrophic failure occurs near a river, the debris may block the river, causing serious damage to the adjacent area. Therefore, examination of the mechanism of such catastrophic slope failures is important with respect to the mitigation of earthquake disasters in mountainous districts, although numerical modeling of such phenomena is rather difficult. In the present study, a new numerical model is developed to simulate an earthquake-induced catastrophic landslide that occured at a typical dip slope, namely, the Yokowatashi Landslide in Japan. In this case, the upper part of the bedrock on the planer tectonic dip surface slid more than 70 m. Only shear-strength degradation at the bedding plane could cause such a long-distance traveling failure. To investigate the strain-softening characteristics of the materials that filled the bedding plane, a series of laboratory tests involving undisturbed block samples was performed. The measured stress-displacement relationships under cyclic loading were numerically modeled as a newly proposed elasto-plastic constitutive model to be used in numerical simulations of landslide, based on the dynamic finite element method. The observed phenomena were appropriately simulated by the proposed method. The mechanism of catastrophic failure is discussed in detail in this paper in order to clarify the relationships between the strain-softening characteristics and the global slope stability. Our newly proposed method to evaluate the possibility of a catastrophic failure was applied to the landslide, and the moment when the slope becomes unstable was able to be predicted. The results confirm that the proposed method can predict the catastrophic failure of a slope.  相似文献   
9.
Chemical modification of zein by bifunctional polycaprolactone (PCL)   总被引:1,自引:0,他引:1  
Prepolymer was synthesized by use of PCL and hexamethylene diisocyanate (HDI), and then used to prepare modified zein-based polymers (ZPs). Solid-state 13C NMR results showed that at least four amino acids (Glu, Gln, Tyr and His) reacted with the prepolymer, and urea-urethane links were prominent. Thermal analysis indicated that micro-phase separation formed between zein matrix and PCL-HDI (PCLH) component in ZPs. With the increasing PCLH content, the melting point of PCL in ZP decreased, and the Tg of zein reduced due to plasticizer role of PCLH. The breaking elongation of modified zein containing 10% PCLH content, increased about 15 times while its strength at break only reduced by about 2 times than that of commercial zein. In addition, with the increasing PCLH content, the flexibility of modified zein sheet improved dramatically with negligible reduction in strength. This indicates that PCL was an elastic fraction in ZPs. Therefore, it is an effective way to improve the mechanical properties of zein by modification with PCL, showing a potential in the field of biodegradable polymers.  相似文献   
10.
Terpendole E is first natural product found to inhibit mitotic kinesin Eg5, but its inhibitory mechanism remains to be revealed. Here, we report the effects of terpendole E and 11ketopaspaline (a new natural terpendole E analogue) on the Eg5–microtubule interaction and in several Eg5 mutants. 11‐Ketopaspaline is a shunt product from terpendole E, and it shows potent inhibitory activity against the microtubule‐stimulated ATPase activity of Eg5. Unlike other Eg5 inhibitors, such as S‐trityl‐L ‐cysteine (STLC) and GSK‐1, both terpendole E and 11‐ketopaspaline only partially inhibited Eg5–microtubule interaction. Furthermore, terpendole E and 11‐ketopaspaline inhibited several Eg5 mutants that are resistant to STLC (Eg5D130A, Eg5L214A) or GSK‐1 (Eg5I299F, Eg5A356T), but with the same extent of inhibition against wild‐type Eg5. Because Eg5D130A and Eg5L214A show cross‐resistance to most known Eg5 inhibitors, which bind the L5 loop, these results suggest that terpendole E and its analogues have a different binding site and/or inhibitory mechanism to those for L5 loop‐binding type Eg5 inhibitors.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号