首页 | 官方网站   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   67篇
  免费   1篇
工业技术   68篇
  2016年   2篇
  2013年   9篇
  2010年   1篇
  2009年   1篇
  2008年   1篇
  2007年   2篇
  2004年   2篇
  2003年   1篇
  2001年   1篇
  2000年   2篇
  1999年   1篇
  1998年   3篇
  1996年   6篇
  1995年   1篇
  1994年   4篇
  1992年   2篇
  1987年   7篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1980年   2篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1976年   3篇
  1975年   1篇
  1972年   2篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
  1966年   1篇
排序方式: 共有68条查询结果,搜索用时 265 毫秒
1.
Young men from poorer backgrounds are associated with high road traffic collision levels. However, solving this problem has proven very difficult. Hence this paper summarises the findings of a UK government funded two-year trial of a cross-discipline intervention to reduce aggressive driving amongst this group.  相似文献   
2.
We examined the emergence of a critical component of sex, response to sexual signals—phonotaxis—in male and female túngara frogs (Physalaemus pustulosus). We determined the ontogenetic trajectories of phonotactic responses as animals developed from metamorphic froglets to reproductive adults. The results demonstrated that species-typical phonotaxis emerges quite early during postmetamorphic development, well before sexual maturity, suggesting that a developmentally early bias in the auditory system for species-typical signals might be a more general phenomenon than previously thought, and that the neural circuits responsible for processing and responding to conspecific advertisement signals in a species-typical manner might develop long before the coordinated behavior is demanded of the organism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
Intraocular infection with herpes simplex virus type I strain F (HSV-1) induces bilateral retinitis, the expression of both MHC class I and II molecules and activation of CD4 and CD8 cells. To investigate the role of MHC upregulation in IFN-gamma mediated antiviral effects in intraocular infection with HSV-1, we infected MHC deficient mice and mice with an additional ectopic site of IFN-gamma production in their retina (rho gamma) intravitreally with HSV-1 into one eye. Protective effects of IFN-gamma in intraocular HSV-1 infection were notable as sparing of the contralateral non-inoculated eye from retinitis, and were not dependent on MHC class I and class II expression, thus limiting the importance of MHC expression for the outcome of viral infection in vivo.  相似文献   
4.
This paper discusses the design, implementation and evaluation of linear finite element programs that distribute their computations over a network of workstations. We consider five different algorithms based on direct, iterative and hybrid equation solvers, each of which partitions and maps the model domain across conventional network hardware. A software architecture based on the client-server model distributes the computations and, at the language level, Berkeley sockets enable communication between processes. We evaluate and describe the performance of these algorithms in terms of execution time and speed-up, and we conclude that distributed solvers, particularly those based on substructuring and static condensation, can be effective even on high-latency communication networks.  相似文献   
5.
Ganglion cells with intraretinal axon collaterals have been described in monkey (Usai et al., 1991), cat (Dacey, 1985), and turtle (Gardiner & Dacey, 1988) retina. Using intracellular injection of horseradish peroxidase and Neurobiotin in in vitro whole-mount preparations of human retina, we filled over 1000 ganglion cells, 19 of which had intraretinal axon collaterals and wide-field, spiny dendritic trees stratifying in the inner half of the inner plexiform layer. The axons were smooth and thin (approximately 2 microm) and gave off thin (<1 microm), bouton-studded terminal collaterals that extended vertically to terminate in the outer half of the inner plexiform layer. Terminal collaterals were typically 3-300 microm in length, though sometimes as long as 700 microm, and were present in clusters, or as single branched or unbranched varicose processes with round or somewhat flattened lobular terminal boutons 1-2 microm in diameter. Some cells had a single axon whereas other cells had a primary axon that gave rise to 2-4 axon branches. Axons were located either in the optic fiber layer or just beneath it in the ganglion cell layer, or near the border of the ganglion cell layer and the inner plexiform layer. This study shows that in the human retina, intraretinal axon collaterals are associated with a morphologically distinct ganglion cell type. The synaptic connections and functional role of these cells are not yet known. Since distinct ganglion cell types with intraretinal axon collaterals have also been found in monkey, cat, and turtle, this cell type may be common to all vertebrate retinas.  相似文献   
6.
7.
A new approach to analyze HDD seeking acoustics is proposed. An acoustic transfer function was derived that has seeking current as input and seeking acoustics as response. The derivation and the advantage and limitation of this acoustic transfer function approach is discussed in details in this paper. HDD seeking acoustics is mainly determined by the seeking current spectrum and the mechanical design. The acoustics transfer function represents the mechanical design, and was used to diagnose trouble mechanical modes and to guide servo design to reduce specific seeking current frequency content. The acoustic transfer function approach also enables quick performance prediction of combination of different mechanical designs and seeking currents. Various HDDs with different seeking current profiles and mechanical designs were evaluated experimentally and numerically. Finally, a new seeking servo algorithm was evaluated, and good agreement was shown between the numerical prediction using the acoustics transfer function approach and the measured seeking acoustics.  相似文献   
8.
The ESR spectra of complexes of fibrous cotton cellulose and cupriammonia dihydroxide or cupriethylene diamine dihydroxide under various experimental conditions were determined. The spectra of both complexes with cotton cellulose were almost identical at ?100 and 25°C. The spectrum of the complex of cupriethylene diamine dihydroxide with cellulose was stable to temperatures as high as 100°C. The sum of the linewidths of the hyperfine components of the spectra for each complex was about 180 gauss. Cotton fibers were combed and aligned with their axes (lengths) parallel to the magnetic field (B); after formation of either of the complexes with cellulose a minumum of hyperfine structure of components centered at H was observed. A maximum of hyperfine structure of these components was observed when the complexed fibers were aligned with their axes perpendicular to the magnetic field (B). The opposite was true of components centered at H. For a complex of cupriethylene diamine dihydroxide and cellulose at 25°C. and at high pH the g was 2.2127 and the g was 2.0476. It was suggested that the alignment of most of the complex was its axis of symmetry at a maximum angle to the axes of the cotton fiber, when the axes of the fibers were in the parallel alignment with the magnetic field. At high pH these observations were even more marked. When ramie was used with cupriethylene diamine dihydroxide at high pH, the contribution of components centered at H to the spectra was zero. Spectra for the copper compounds alone and complexed with cellobiose are also reported.  相似文献   
9.
We used a temperature‐sensitive fluorescent dye, perylene, to monitor the true resin temperature during extrusion of polycarbonate. The measurement involved doping polycarbonate with perylene and detecting fluorescence with an optical sensor that accesses a standard instrumentation port on a barrel of a single‐screw extruder. The sensor's confocal optics design permits fluorescence intensity measurements as a function of position. Using a previously established calibration function, temperature and temperature gradients were obtained from the measured fluorescence. Because the origin of the measurement is the fluorescent dye molecule that is soluble in the resin, this method allows temperature measurement of the polymer without interference from the surrounding metal parts. With the sensor looking over the screw, temperature profiles from the barrel wall to the core of the screw were obtained as a function of screw speed, screw design and resin melt flow rate. Polym. Eng. Sci. 44:2148–2157, 2004. © 2004 Society of Plastics Engineers.
  • 1 This paper is a contribution from the National Institute of Standards and Technology, and, thus, is not subject to copyright in the United States.
  •   相似文献   
    10.
    Vehicles have been proven to be an ideal means for terrorists because they can be meticulously prepared well in advance before being deployed in urban and public places. To increase the risk and burden of explosive ordnance disposal teams, third‐party vehicles have also been used to block the access path to the explosive loaded vehicle. In this paper, we present a multirobot system that can remove vehicles from confined spaces with delicate handling, swiftly and in any direction to a safer disposal point. The new lifting robots, capable of omnidirectional movement, autonomously underride the identified vehicle and dock to its wheels for a synchronized lifting and extraction. The validity and efficiency of the novel robotic system is illustrated via experiments in an indoor parking lot, demonstrating successful autonomous navigation, docking, lifting, and extraction of a conventional car for a total covered distance of 20 m.  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-23

    京公网安备 11010802026262号