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   259篇
  免费   0篇
  国内免费   1篇
电工技术   1篇
化学工业   56篇
金属工艺   4篇
机械仪表   4篇
建筑科学   15篇
能源动力   15篇
轻工业   12篇
水利工程   1篇
无线电   34篇
一般工业技术   52篇
冶金工业   11篇
原子能技术   5篇
自动化技术   50篇
  2023年   1篇
  2021年   12篇
  2020年   4篇
  2019年   4篇
  2018年   1篇
  2017年   4篇
  2016年   7篇
  2014年   5篇
  2013年   14篇
  2012年   14篇
  2011年   25篇
  2010年   15篇
  2009年   16篇
  2008年   22篇
  2007年   16篇
  2006年   17篇
  2005年   6篇
  2004年   5篇
  2003年   10篇
  2002年   3篇
  2001年   4篇
  1999年   2篇
  1998年   2篇
  1997年   3篇
  1996年   2篇
  1995年   4篇
  1993年   3篇
  1992年   2篇
  1991年   6篇
  1990年   3篇
  1989年   2篇
  1988年   1篇
  1987年   3篇
  1985年   2篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
  1980年   2篇
  1979年   5篇
  1977年   1篇
  1976年   1篇
  1970年   3篇
  1968年   1篇
排序方式: 共有260条查询结果,搜索用时 15 毫秒
101.
In this paper we propose a way to study leakage paths for electrons during data retention in floating gate non-volatile memories and especially in EEPROM memory cells. We investigate the main leakage paths, through tunnel oxide as well as through the tri-layer stack oxide “oxide/nitride/oxide” (ONO). We used a TCAD simulation of the full EEPROM cell to precisely determine the control gate bias voiding the electric field through ONO or tunnel oxide. Data retention measurements are then performed with simulated bias. We highlight the fact that leakage paths during data retention are different for extrinsic and intrinsic cells. Indeed, extrinsic behavior disappears when voiding electric field across tunnel oxide, showing these cells leak through tunnel oxide, whereas intrinsic behavior is the same whatever the electric field across tunnel oxide, showing charge loss in intrinsic cells is due to another path.  相似文献   
102.
This paper demonstrates how the light transmitted through a stretched optical fibre may be used to detect its modes of vibration. In particular, replacing strings of a musical instrument with optical fibre allows the fabrication of a simple acoustic instrument with a single laser source and single detector. The detected signal contains rich harmonics of the vibrating fibre. This device may be used as a vibration, temperature or strain sensor, or simply as a musical instrument. Coating the optical fibre with novel materials such as PZLT may well allow a modification of vibration properties to enhance, suppress certain harmonics or lead to the development of simple electric field sensors.  相似文献   
103.
It is well-known that if certain trace elements are present in cast iron melts the morphology of the graphite precipitates can be altered. In order to understand the effect of doping elements on primary growth of graphite, pure Fe?CSb alloys were prepared by induction melting. They were then placed in graphite crucibles and heated to a temperature above the Fe?CC eutectic so that the charge became saturated in carbon and melted. To obtain Fe?CCe alloys, metallic Ce was added at the bottom of a graphite crucible and covered with iron, and then heated as for the Fe?CSb charge. In both cases, the melt was then cooled and held slightly above the eutectic temperature so that primary graphite crystals, which had nucleated on the crucible walls and then detached from it, could grow freely in the melt. The influence of the added elements on graphite growth was revealed by the change in the shape and distribution of the crystals compared to those obtained in similar experiments carried out with pure Fe. The experiments were made in air and vacuum so as to point out possible interactions between the elements present in the melt and oxygen.  相似文献   
104.
The recrystallization texture evolution in heavily cold-rolled (93%) FeCo-2V alloy with annealing temperature and time was investigated by X-ray diffraction and electron backscatter diffraction. It was found that the orientation density of α-fiber texture component fluctuates with increasing annealing temperature and time. The transmission electron microscopy images show that abundant precipitates appear inside the recrystallized grains and around the grain boundaries. The amount and size of the precipitate...  相似文献   
105.
We derive an exact deterministic nonlinear observer to compute the continuous state of an inertial navigation system based on partial discrete measurements, the so-called strap-down problem. Nonlinear contraction is used as the main analysis tool, and the hierarchical structure of the system physics is systematically exploited. The paper also discusses the use of nonlinear measurements, such as distances to time-varying reference points.  相似文献   
106.
Chronic kidney disease (CKD), secondary to renal fibrogenesis, is a public health burden. The activation of interstitial myofibroblasts and excessive production of extracellular matrix (ECM) proteins are major events leading to end-stage kidney disease. Recently, interleukin-15 (IL-15) has been implicated in fibrosis protection in several organs, with little evidence in the kidney. Since endogenous IL-15 expression decreased in nephrectomized human allografts evolving toward fibrosis and kidneys in the unilateral ureteral obstruction (UUO) model, we explored IL-15’s renoprotective role by pharmologically delivering IL-15 coupled or not with its soluble receptor IL-15Rα. Despite the lack of effects on myofibroblast accumulation, both IL-15 treatments prevented tubulointerstitial fibrosis (TIF) in UUO as characterized by reduced collagen and fibronectin deposition. Moreover, IL-15 treatments inhibited collagen and fibronectin secretion by transforming growth factor-β (TGF-β)-treated primary myofibroblast cultures, demonstrating that the antifibrotic effect of IL-15 in UUO acts, in part, through a direct inhibition of ECM synthesis by myofibroblasts. In addition, IL-15 treatments resulted in decreased expression of monocyte chemoattractant protein 1 (MCP-1) and subsequent macrophage infiltration in UUO. Taken together, our study highlights a major role of IL-15 on myofibroblasts and macrophages, two main effector cells in renal fibrosis, demonstrating that IL-15 may represent a new therapeutic option for CKD.  相似文献   
107.
锌与锌合金镀层三价铬钝化工艺的发展   总被引:1,自引:0,他引:1  
0概述 三价铬钝化最早在工业上获得应用的是彩色钝化,其色度是通过在钝化膜中共沉积合金金属或其他金属元素的盐或氧化物而得到加强.黑色钝化膜最先在锌-铁和锌-镍合金镀层上获得,随后通过添加金属黑色氧化物、金属硫化物或磷衍生物,在锌镀层上也获得黑色钝化层.  相似文献   
108.
This paper presents a three-dimensional (3-D) shape reconstruction/intrapatient rigid registration technique used to establish a Nephron-Sparing Surgery preoperative planning. The usual preoperative imaging system is the Spiral CT Urography, which provides successive 3-D acquisitions of complementary information on kidney anatomy. Because the kidney is difficult to demarcate from the liver or from the spleen only limited information on its volume or surface is available. In this paper, we propose a methodology allowing a global kidney spatial representation on a spherical harmonics basis. The spherical harmonics are exploited to recover the kidney 3-D shape and also to perform intrapatient 3-D rigid registration. An evaluation performed on synthetic data showed that this technique presented lower performance then expected for the 3-D shape recovering but exhibited registration results slightly more accurate as the iterative closest point technique with faster computation time.  相似文献   
109.
Cold-smoked salmon is a lightly preserved fish product in which a mixed microbial flora develops during storage and where the interactive behaviour of micro-organisms may contribute to their growth and spoilage activity. The aim of this study was to assess the effect of the bacterial interactions between the main species contaminating the cold-smoked salmon on bacterial growth, chemical and sensory changes, and spoilage. First, Carnobacterium piscicola, Photobacterium phosphoreum, Lactobacillus sakei, Vibrio sp., Brochothrix thermosphacta and Serratia liquefaciens-like were inoculated as pure cultures on sterile cold-smoked salmon. All bacterial species grew well; Vibrio sp. was the fastest and L. sakei strains developed very rapidly as well with a high maximum cell density on cold-smoked salmon blocks (up to 10(9) cfu g(-1) after 10 days at 8 degrees C). Based on sensory analysis, Vibrio sp. was identified as non-spoilage bacteria, C. piscicola as very lightly and B. thermosphacta as lightly spoiling. L. sakei and S. liquefaciens-like were found to be the most spoiling bacteria. Secondly, C. piscicola and L. sakei, two species frequently occurring in the lactic flora of the product, were inoculated together and each of them in mixed cultures with respectively P. phosphoreum, Vibrio sp., B. thermosphacta, and S. liquefaciens-like. The growth of L. sakei was shown to strongly inhibit most of the co-inoculated strains i.e. P. phosphoreum, B. thermosphacta, S. liquefaciens-like and, to a lesser extent, Vibrio sp. The growth of C. piscicola seemed to be enhanced with B. thermosphacta and to develop earlier with P. phosphoreum and Vibrio sp. Conversely, S. liquefaciens-like and P. phosphoreum were weakly inhibited by C. piscicola. The main observation resulting from the sensory evaluation was the delay in the appearance of the spoilage characteristics in the mixed cultures with L. sakei, in particular L. sakei/ S. liquefaciens-like. On the other hand, the spoilage activity of the non-spoiler strains Vibrio sp. or the moderate spoilage strains B. thermosphacta and C. piscicola was increased when they were associated together. It is concluded that the spoilage behaviour of micro-organisms in mixed culture is significantly different from pure culture and explain the difficulty to find robust quality indices for this product.  相似文献   
110.
The mechanical behavior of a Fe80Zr10Cr10 alloy has been studied at ambient and high temperature. This Fe80Zr10Cr10 alloy, whoose microstructure is formed by alternate lamellae of Laves phase and ferrite, constitutes a very simple example of an in situ CMA phase composite. The role of the Laves phase type was investigated in a previous study while the present work focuses on the influence of the microstructure length scale owing to a series of alloys cast at different cooling rates that display microstructures with Laves phase lamellae width ranging from ~50 nm to ~150 nm. Room temperature compression tests have revealed a very high strength (up to 2 GPa) combined with a very high ductility (up to 35%). Both strength and ductility increase with reduction of the lamella width. High temperature compression tests have shown that a high strength (900 MPa) is maintained up to 873 K. Microstructural study of the deformed samples suggests that the confinement of dislocations in the ferrite lamellae is responsible for strengthening at both ambient and high temperature. The microstructure scale in addition to CMA phase structural features stands then as a key parameter for optimization of mechanical properties of CMA in situ composites.  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