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   588篇
  免费   8篇
  国内免费   1篇
电工技术   49篇
综合类   3篇
化学工业   167篇
金属工艺   10篇
机械仪表   8篇
建筑科学   17篇
能源动力   15篇
轻工业   44篇
水利工程   4篇
石油天然气   1篇
无线电   38篇
一般工业技术   82篇
冶金工业   117篇
原子能技术   12篇
自动化技术   30篇
  2023年   3篇
  2022年   8篇
  2021年   13篇
  2020年   6篇
  2019年   4篇
  2018年   3篇
  2017年   4篇
  2016年   11篇
  2015年   2篇
  2014年   11篇
  2013年   22篇
  2012年   15篇
  2011年   26篇
  2010年   11篇
  2009年   15篇
  2008年   36篇
  2007年   25篇
  2006年   19篇
  2005年   30篇
  2004年   26篇
  2003年   23篇
  2002年   22篇
  2001年   9篇
  2000年   14篇
  1999年   14篇
  1998年   42篇
  1997年   26篇
  1996年   15篇
  1995年   16篇
  1994年   14篇
  1993年   14篇
  1992年   8篇
  1991年   5篇
  1990年   5篇
  1988年   4篇
  1987年   4篇
  1986年   2篇
  1985年   12篇
  1984年   13篇
  1983年   3篇
  1982年   6篇
  1981年   4篇
  1980年   5篇
  1979年   3篇
  1978年   5篇
  1977年   6篇
  1976年   7篇
  1972年   1篇
  1966年   1篇
  1965年   1篇
排序方式: 共有597条查询结果,搜索用时 15 毫秒
41.
Ureteral triplication is a rare congenital anomaly of the upper urinary tract. It is reported to be associated with an increased incidence of congenital anomalies as well as a predisposition to infection and calculus formation. We report a case of type 1 variant of ureteral triplication associated with vesicoureteral reflux into lower and mid pole ureters in a solitary kidney. To our knowledge ureteral triplication in a solitary kidney has not been described previously.  相似文献   
42.
Due to the recent popularization of mobile multimedia broadcasting, broadcasting continuous media data such as audio and video has attracted great deal of attention. In general continuous media data broadcasting, since clients have to wait to receive data before playing it, various schemes to reduce waiting time have been studied. Some reduce the waiting time by dividing the data into several segments and broadcasting preceding segments frequently with a single channel. However, by dividing the data into numerous segments and producing an effective broadcast schedule, the waiting time can be further reduced. In this paper, we propose a scheduling protocol to reduce waiting time with large-scale data segmentation.  相似文献   
43.
It is necessary to use renewable energy, such as photovoltaic, wind power, and biomass energy, from the viewpoint of CO2 regulation and environmental protection of the Earth. In recent years, the tendency is toward larger wind power generation systems to achieve cheaper electricity. Generators having capacities of 1500 kW to 2000 kW tend to dominate the market. However, a large wind power generation system has limitations in terms of location and can be installed only in the suburbs. At the same time, a city‐type compact wind power generation system, designed for city needs, has more flexibility and can be installed in the residential areas of a city. In this paper, we introduce an original control operation system called a “pump‐up” operation system, designed to effectively use the city wind, and report the results of its field test. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(2): 56–63, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20440  相似文献   
44.
A passive aerodynamic control method for suppression of the wind-induced instabilities of a very long span bridge is presented in this paper. The control system consists of additional control flaps attached to the edges of the bridge deck. Control flap rotations are governed by prestressed springs and additional cables spanned between the control flaps and an auxiliary transverse beam supported by the main cables of the bridge. The rotational movement of the flaps is used to modify the aerodynamic forces acting on the deck and provides aerodynamic forces on the flaps used to stabilize the bridge. A time-domain formulation of self-excited forces for the whole three-dimensional suspension bridge model is obtained through a rational function approximation of the generalized Theodorsen function and implemented in the FEM formulation. This paper lays the theoretical groundwork for the one that follows.  相似文献   
45.
Five sterylglycosides (acylmono-, mono-, di tri- and tetraglycosylsterol) and a saponin were isolated from Adzuki beans and characterized. In the glycosylsterols, the principal component sterols were sitosterol and stigmasterol; the major sugar component was glucose. The glucose units were shown to be linked by β1,6-bonds. The three oligoglycosylsterols were shown to be gentiobiosylsterol, gentiotriosylsterol and gentiotetraosylsterol; the latter two are novel sterylglycosides. The saponin was identified as glucopyranosyl-(β1→2)-glucopyranurosyl-(β1→3′)-soyasapogenol B (Azukisaponin I) which had previously been found in Adzuki beans.  相似文献   
46.
Some studies for radiological protection of the environment have been made at the National Institute of Radiological Sciences (NIRS). Transfer of radionuclides and related elements has been investigated for dose estimation of non-human biota. A parameter database and radionuclide transfer models have been also developed for the Japanese environments. Dose (rate)-effect relationships for survival, growth and reproduction have been investigated in conifers, Arabidopsis, fungi, earthworms, springtails, algae, duckweeds, daphnia and medaka. Also genome-wide gene expression analysis has been carried out by high coverage expression profiling (HiCEP). Effects on aquatic microbial communities have been studied in experimental ecosystem models, i.e., microcosms. Some effects were detected at a dose rate of 1 Gy day(-1) and were likely to arise from interspecies interactions. The results obtained at NIRS have been used in development of frameworks for environmental protection by some international bodies, and will contribute to environmental protection in Japan and other Asian countries.  相似文献   
47.
La(3+) and not Ca(2+) increases methanol dehydrogenase (MDH) activity in Methylobacterium radiotolerans NBRC15690. La(3+)- and Ca(2+)-MDH-like proteins were found to be homodimeric (α(2)) and heterotetrameric (α(2)β(2)), respectively. N-terminal amino acid sequences of these proteins revealed that La(3+)- and Ca(2+)-MDH-like proteins were encoded by xoxF and mxaFI, respectively.  相似文献   
48.
The present paper examines the accuracy of two models used to predict the capacity of single square plate anchors used in multi-anchor wall (MAW) systems constructed in Japan. Measured anchor plate capacities from full-scale in situ load tests reported in the literature are compared to predicted values using the analytical model recommended in Japan. A modified anchor capacity model is proposed that preserves the general form of the PWRC equation, but introduces correction factors to improve accuracy. The correction factors are empirically-based and are selected by back-fitting measured loads to achieve a resistance bias mean equal to one and a low coefficient of variation (COV) in bias values. The results of a large number of small-scale anchor capacity tests carried out in pullout boxes were used to guide the selection of back-fitted parameters. The correction factors account for the influence of the confining pressure (anchor depth), the plate size and the anchor rod length on the anchor plate capacity. New Nc and Nq factors are also presented as part of the new model. The bias statistics for the two models comprise an important contribution to future reliability-based calibrations of the ultimate anchor capacity limit state for MAW systems in Japan.  相似文献   
49.
A 48-year old woman underwent surgery for an aortic arch aneurysm with stenosis or dilatation of three arch vessels caused by aortitis syndrome. Total arch replacement and reconstruction of three arch vessels were performed with hypothermic selective cerebral perfusion (SCP). To avoid atheroembolism and malperfusion to the brain, the rt. common carotid artery was perfused via the rt. subclavian artery through the dacron vascular graft and the lt. subclavian artery was cannulated and perfused distally to stenosis. A 65-year-old man who had an atherosclerotic aortic arch aneurysm with severe stenosis of the brachiocephalic artery underwent operation. In the operation, extracorporeal circulation was instituted with the arterial return through the lt. subclavian artery. Same as case 1, total arch replacement and reconstruction of three arch vessels were performed under hypthermic SCP. In this case, the left common carotid artery was transected and cannulated directly into the vessel, instead of cannulation through the aortic lumen because of atheromatous plaques in the orifice of the left common carotid artery. The patients recovered uneventfully and doing well now.  相似文献   
50.
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