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   479篇
  免费   9篇
  国内免费   6篇
电工技术   5篇
综合类   14篇
化学工业   28篇
金属工艺   6篇
机械仪表   4篇
建筑科学   16篇
能源动力   6篇
轻工业   37篇
水利工程   6篇
武器工业   1篇
无线电   15篇
一般工业技术   41篇
冶金工业   238篇
原子能技术   21篇
自动化技术   56篇
  2024年   1篇
  2022年   7篇
  2021年   6篇
  2020年   3篇
  2019年   3篇
  2018年   4篇
  2017年   1篇
  2016年   6篇
  2015年   6篇
  2014年   7篇
  2013年   32篇
  2012年   14篇
  2011年   17篇
  2010年   8篇
  2009年   20篇
  2008年   9篇
  2007年   8篇
  2006年   12篇
  2005年   6篇
  2004年   15篇
  2003年   7篇
  2002年   11篇
  2001年   9篇
  2000年   5篇
  1999年   11篇
  1998年   72篇
  1997年   45篇
  1996年   36篇
  1995年   16篇
  1994年   19篇
  1993年   15篇
  1992年   1篇
  1991年   5篇
  1990年   3篇
  1989年   6篇
  1988年   3篇
  1987年   2篇
  1986年   1篇
  1985年   3篇
  1984年   4篇
  1982年   2篇
  1981年   2篇
  1980年   4篇
  1978年   3篇
  1977年   7篇
  1976年   12篇
  1970年   1篇
  1955年   1篇
  1946年   1篇
  1945年   2篇
排序方式: 共有494条查询结果,搜索用时 31 毫秒
91.
Fully validated material databases are needed for coherent technological developments in any R&D field. For nuclear fusion technology (NFT), within a near-term perspective of qualification and licensing of nuclear components and systems, this goal is both compulsory and urgent. This mandatory requirement applies for the particular case of the Pb-Li eutectic database as fusion reactor material. Pb16Li is today a reference breeder material in diverse fusion R&D programs worldwide. Technical consensus on most part of the material database inputs seems a major technological objective. In this work Pb16Li material database inputs for NFT have been systematically reviewed. Database inputs (bulk, thermal, physical-chemistry properties, and H-isotopes transport) are discussed and extended to base magnetohydrodynamic (MHD) properties, values for non-dimensional parameters and pipe/channel correlations in 2-phases dispersion models. Ongoing efforts to develop the Pb16Li material database as a computing expert system are reported.  相似文献   
92.
Conventionally used in the food industry as stabilizing, thickening, gelling, and suspending or dispersing agents, non-starch polysaccharides such as xanthan gum are known to improve the texture of certain frozen products. Another polysaccharide that has received significant attention in recent years is chitosan, a natural biopolymer derived from chitin. In the wake of growing interest in finding ideal encapsulating agents for probiotics, non-starch polysaccharides have been investigated. Scattered research can be found on the effect of each individual polysaccharide, but there remains a void in the literature in terms of closely comparing the characteristics of non-starch polysaccharides for these applications, especially when more than one biopolymer is employed. A good understanding of the tools capable of elucidating the underlying mechanisms involved is essential in ushering further development of their applications. Therefore, it is this review’s intention to focus on the selection criteria of non-starch polysaccharides based on their rheological properties, resistance to harsh conditions, and ability to improve sensory quality. A variety of critical tools is also carefully examined with respect to the attainable information crucial to frozen food and microencapsulation applications.  相似文献   
93.
1.技术概述 VK05CFL是一种用于驱动微型荧光灯的自振荡转换器,采用意法半导体的VIPower M3-3专利技术制造而成,允许在同一芯片上集成控制部分和电源级。电源级是一个“发射器开关”,其构成是在级联配置内放置一个双极高压复合晶体管和一个低压MOSFET,因此,在高击穿电  相似文献   
94.
FRP Confinement of Square Masonry Columns   总被引:4,自引:0,他引:4  
The problem of masonry columns subjected to structural deficiency under axial load was studied and reported in this paper. The results of an extensive experimental campaign are presented in order to show the behavior of columns built with clay or with calcareous blocks, commonly found in southern Italy, especially in historical buildings. Rectangular masonry columns were tested for a total of 33 specimens; uniaxial compression tests were conducted on columns taking into account the influence of several variables: different strengthening schemes (internal and/or external confinement), curvature radius of the corners, amount of fiber-reinforced polymer (FRP) reinforcement, cross-section aspect ratio, and material of masonry blocks. Materials characterization was preliminarily carried out including a mechanical test on plain masonry. For all cases the experimental results evidenced a significant increase in load carrying capacity and ductility after FRP strengthening, which identified the columns as ductile elements despite the brittle nature of the unconfined masonry. Differences in mechanical behavior, due to the geometry of the columns, to the nature of different materials, to different strengthening schemes, and to the amount of reinforcement, are presented and discussed in the paper. The calibration of design equations recently developed by Italian National Research Council, CNR was conducted to compare analytical prediction and experimental results. The same procedure was applied to calibrate an analytical model recently published, in which the existing coefficients are related only to clay. Here the model is applied to limestone for the first time. Thus, new important information is furnished to researchers and practitioners involved in structural assessment and strengthening of compressed elements in historical buildings.  相似文献   
95.
The inositol 1,4,5-triphosphate receptor type 1 (ITPR1) gene encodes an InsP3-gated calcium channel that modulates intracellular Ca2+ release and is particularly expressed in cerebellar Purkinje cells. Pathogenic variants in the ITPR1 gene are associated with different types of autosomal dominant spinocerebellar ataxia: SCA15 (adult onset), SCA29 (early-onset), and Gillespie syndrome. Cerebellar atrophy/hypoplasia is invariably detected, but a recognizable neuroradiological pattern has not been identified yet. With the aim of describing ITPR1-related neuroimaging findings, the brain MRI of 14 patients with ITPR1 variants (11 SCA29, 1 SCA15, and 2 Gillespie) were reviewed by expert neuroradiologists. To further evaluate the role of superior vermian and hemispheric cerebellar atrophy as a clue for the diagnosis of ITPR1-related conditions, the ITPR1 gene was sequenced in 5 patients with similar MRI pattern, detecting pathogenic variants in 4 of them. Considering the whole cohort, a distinctive neuroradiological pattern consisting in superior vermian and hemispheric cerebellar atrophy was identified in 83% patients with causative ITPR1 variants, suggesting this MRI finding could represent a hallmark for ITPR1-related disorders.  相似文献   
96.
计算机辅助大规模人群疏散平台   总被引:1,自引:1,他引:0       下载免费PDF全文
针对现有疏散策略的不足,构建一个计算机辅助大规模人群疏散平台,为政府相关部门在城市建设和防灾规划中提供科学决策支持。该平台集成了疏散仿真模型和基于时变动态流问题的路网优化模型,引入组件式GIS技术,采用模块化多层体系结构建立了一个准确、实时的疏散引导系统。  相似文献   
97.
Spreadsheets are powerful programs for personal computers, and in many respects they have a clear edge over established programming languages such as FORTRAN or BASIC for simple day-to-day engineering applications. Modern spreadsheets such as lotus 1–2-3(TM), Excel (TM), Symphony(TM), Jazz (TM), Quattro (TM), etc. are very easy to learn and they can be used for a multitude of tasks including desktop calculation, text editing, data base functions and graphics. The one decided advantage of spreadsheets is that they are totally interactive; a user can use spreadsheets directly without having to worry about data files and output files. The ideas explained in this paper are applicable to most commercially available spreadsheets with the particular examples shown applicable to Lotus 1–2-3. The technique of "formatted" worksheets has been developed and successfully used by the author in teaching and in his professional work for several years. A thorough knowledge of spreadsheets is imperative for the efficient application of this technique. Some practical ideas plus a set of macros will be shown.  相似文献   
98.
The O-specific polysaccharide of Proteus mirabilis O28 was found to contain D-galactose, D-galacturonic acid (GalA), 2-acetamido-2-deoxy-D-glucose, L-serine, L-lysine, and O-acetyl groups in molar ratios 1:2:1:1:1:1, the amino acids being linked via their alpha-amino group to the carboxyl group of GalA. The polysaccharide was studied using 1H- and 13C-NMR spectroscopy, including selective spin-decoupling, one-dimensional total correlation spectroscopy, two-dimensional homonuclear correlation spectroscopy (COSY), heteronuclear 13C,1H COSY, one-dimensional NOE, and two-dimensional rotating-frame NOE spectroscopy and partial acid hydrolysis followed by borohydride reduction, methylation, and GLC/MS analysis of the derived glycosyl alditols. The following structure of the repeating unit was established: [formula: see text] Epitope specificity of the P. mirabilis O28 polysaccharide was analysed using a homologous rabbit polyclonal antiserum in quantitative precipitation, passive immunohemolysis, and inhibition of passive immunohemolysis. Study with related synthetic glycopolymers (2-acrylamidoethyl glycosides of amides of alpha-D-GalA with amino acids copolymerised with acrylamide) showed the importance of D-GalA(L-Lys) for manifesting serological specificity of the O-antigen. Serological cross-reactions between P. mirabilis O28, S1959, and R14/S1959 (a transient-like form) are discussed.  相似文献   
99.
Interaction with web services enabled marketplaces would be greatly facilitated if users were given a high level service request language to express their goals in complex business domains. This can be achieved by using a planning framework which monitors the execution of planned goals against predefined standard business processes and interacts with the user to achieve goal satisfaction. We present a planning architecture that accepts high level requests, expressed in a service request language known as XSRL. The planning framework is based on the principle of interleaving planning and execution. This is accomplished on the basis of refinement and revision as new service-related information is gathered from service repositories such as UDDI and web services instances, and as execution circumstances necessitate change. The planning system interacts with the user whenever confirmation or verification is needed.  相似文献   
100.
JH Aiello 《Canadian Metallurgical Quarterly》1998,23(2):12-3, 17-8, 23-4 passim; quiz 32-3
Diabetic nephropathy is the leading cause of end-stage renal disease in the United States and is associated with significant human and economic cost. It is recognized that care of the person with diabetes should be focused on the prevention of the many devastating long-term complications of the disease. The primary care provider is in a key position to implement good preventive care. Monitoring for microalbuminuria is the accepted method for identifying early nephropathy. Individual providers need to be aware of current guidelines for performing screening exams. Once early nephropathy is detected, prudent care with tight glycemic control, angiotension-converting enzyme therapy, control of hypertension, and lifestyle risk-factor modification are warranted. Currently, there is strong indication that the progression of renal disease can be slowed with appropriate early interventions. Positive outcomes are dependent on timely detection of microalbuminuria.  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