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   3167篇
  免费   202篇
  国内免费   4篇
电工技术   62篇
综合类   1篇
化学工业   848篇
金属工艺   42篇
机械仪表   72篇
建筑科学   151篇
矿业工程   1篇
能源动力   101篇
轻工业   243篇
水利工程   10篇
石油天然气   3篇
武器工业   1篇
无线电   290篇
一般工业技术   574篇
冶金工业   129篇
原子能技术   27篇
自动化技术   818篇
  2024年   5篇
  2023年   41篇
  2022年   130篇
  2021年   148篇
  2020年   76篇
  2019年   89篇
  2018年   98篇
  2017年   92篇
  2016年   143篇
  2015年   113篇
  2014年   145篇
  2013年   219篇
  2012年   202篇
  2011年   230篇
  2010年   192篇
  2009年   190篇
  2008年   177篇
  2007年   165篇
  2006年   117篇
  2005年   93篇
  2004年   117篇
  2003年   97篇
  2002年   63篇
  2001年   50篇
  2000年   42篇
  1999年   35篇
  1998年   28篇
  1997年   20篇
  1996年   35篇
  1995年   27篇
  1994年   24篇
  1993年   19篇
  1992年   19篇
  1991年   10篇
  1990年   6篇
  1989年   11篇
  1988年   2篇
  1987年   12篇
  1986年   5篇
  1985年   15篇
  1984年   17篇
  1983年   9篇
  1982年   7篇
  1981年   7篇
  1980年   3篇
  1979年   6篇
  1978年   4篇
  1977年   6篇
  1975年   3篇
  1973年   3篇
排序方式: 共有3373条查询结果,搜索用时 15 毫秒
81.
A new algorithm for the integration of partially overlapping range images into a triangular mesh is presented. The algorithm consists of three main steps: it locates the intersections between the range surfaces and a reference grid chosen by the user, then merges all nearly coincident and redundant intersections according to a proximity criterion, and, finally, reconstructs the merged surface(s) from the filtered intersection set. Compared with previous methods, which adopt a volumetric approach, our algorithm shows lower computational costs and improves the accuracy of the surfaces produced. It takes into account the quality of the input measurements and is able to patch small holes corresponding to the parts of the 3D scanned object that were not observed by the acquisition device. The algorithm has been tested on several datasets of range maps; graphical and numeric results are reported.  相似文献   
82.
Proteinuria is a broad term used to describe the pathological presence of proteins, including albumin, globulin, Bence-Jones protein, and mucoprotein in the urine. When persistent, proteinuria is a marker of kidney damage and represents a reliable predictor of the risk of progression of renal failure. Medical nutrition therapy is imperative for patients with proteinuria because it may slow the progression of renal disease. The aim of this review is to explore different nutritional approaches in the management of proteinuria and their influence on pathophysiological processes. As such, protein restriction is the main dietary intervention. Indeed, other management approaches are frequently used to reduce it regarding micro and macronutrients, but also the dietary style. Among these, the nutritional approach represents one of the most used and controversial interventions and the studies rarely take the form of randomized and controlled trials. With this work we aspire to analyze current clinical knowledge of how nutrition could influence proteinuria, potentially representing a useful tool in the management of proteinuric nephropathy.  相似文献   
83.
Interleukin (IL)-37 and IL-33 are among the latest cytokines identified, playing a role in several inflammatory conditions, spanning from systemic conditions to tumors to localized diseases. As newly discovered interleukins, their role is still scarcely understood, but their potential role as therapeutic targets or disease activity markers suggests the need to reorganize the current data for a better interpretation. The aim of this review is to collect and organize data produced by several studies to create a complete picture. The research was conducted on the PubMed database, and the resulting articles were sorted by title, abstract, English language, and content. Several studies have been assessed, mostly related to atopic dermatitis and immunologic pathways. Collective data demonstrates a pro-inflammatory role of IL-33 and an anti-inflammatory one for IL-37, possibly related to each other in an IL-33/IL-37 axis. Although further studies are needed to assess the safety and plausibility of targeting these two interleukins for patients affected by skin conditions, the early results indicate that both IL-33 and IL-37 represent markers of disease activity.  相似文献   
84.
The vitality demonstration refers to determining if an injury has been caused ante- or post-mortem, while wound age means to evaluate how long a subject has survived after the infliction of an injury. Histology alone is not enough to prove the vitality of a lesion. Recently, immunohistochemistry, biochemistry, and molecular biology have been introduced in the field of lesions vitality and age demonstration. The study was conducted according to the preferred reporting items for systematic review (PRISMA) protocol. The search terms were “wound”, “lesion”, “vitality”, “evaluation”, “immunohistochemistry”, “proteins”, “electrolytes”, “mRNAs”, and “miRNAs” in the title, abstract, and keywords. This evaluation left 137 scientific papers. This review aimed to collect all the knowledge on vital wound demonstration and provide a temporal distribution of the methods currently available, in order to determine the age of lesions, thus helping forensic pathologists in finding a way through the tangled jungle of wound vitality evaluation.  相似文献   
85.
昨天/明天: 意大利城市保护与发展50年   总被引:1,自引:0,他引:1  
本文记录了意大利城市保护的理论和文化信息,更重要的是,它展示了由城市和区域部门执行的具体保护案例,并展示了大学研究中心在保护技术和方法上的进步。主要分为4个部分:历史、城市议题、景观议题、培训和国际合作。从城市设计的理念和技术的角度,向世人解析意大利古罗马建筑如何在现代化城市进程中愈加焕发时尚气息的领先技术。中国现阶段正经历着经济快速发展所带来的种种迷惑,或许能从分享中找到答案。  相似文献   
86.
J-integral has been calculated along the free-of-stress border of deep and shallow rounded notches under torsion, under the hypothesis of a linear elastic behaviour of the material. Two exact closed-form solutions have been obtained which make it explicit the influence of the notch opening angle and the notch root radius. When the notch root radius tends to zero the proposed solution matches the expression for the corresponding pointed V-notch case.  相似文献   
87.
The sewage sludge dewatering produced by wastewater treatment plants (WWTP) is a multifaceted process due to the presence of colloid fractions. Electro-osmosis could be a suitable technique to reduce the water content of the final sludge. Electric fields of 10, 15, and 20?V/cm have been studied for electro-osmosis tests under the pressure of a static or rotating piston, obtaining a dry solids content up to 40–45%, with respect to 25–30% obtained by mechanical methods. In order to optimize the process, the corrosion behavior and the wear of the anodic material appear to be the main critical aspects, due to the high circulating current density and the use of a rotating electrode. We compared the efficiency and the corrosion resistance of dimensionally stable anodes (DSA) with respect to bare stainless steel (AISI 304) and stainless steel coated by PVD technique with TiN, AlTiN, and DLC. Characterization of the anode surfaces by SEM and potentiodynamic tests show that DSA is the most suitable material for our application. However, efficiencies of the electro-osmosis processes have been found comparable, in terms of developed current densities and total energy consumptions, for short-test duration.  相似文献   
88.
The powder diffraction patterns of spherical nanocrystals made of five different fcc metals were generated using atomistic models within a Molecular Dynamics simulation. Static and dynamic effects are interpreted and discussed within the framework of two different approaches, respectively, based on (1) a Reciprocal Space and (2) a Direct Space representation of diffraction. Chosen elements display a wide range of properties, especially related to material stiffness and elastic anisotropy, so to deeply challenge interpretation paradigms. The effect of the shape on static and dynamic features is also addressed.  相似文献   
89.
90.
The aim of this study was to develop and validate an efficient analytical method based on gas chromatography/tandem mass spectrometry (GC/MS/MS) for detection and quantification of six pyrethroids residues (Phenothrin, Permethrin, Cyfluthrin, Cypermethrin, Deltamethrin and Fenvalerate) in chicken eggs. The method was based on a preliminary liquid–liquid extraction of albumen‐free yolk samples, followed by a clean‐up by solid‐phase extraction. GC/MS/MS analyses were carried out in the selected reaction monitoring mode. Validation parameters such as specificity, detection capability, decision limit, precision, recovery, stability and ruggedness were determined, resulting in compliance with Decision 2002/657/EC. No complicated apparatus are required; moreover, low volumes of organic solvents and a nonintensive manual labour are required. These low costs and simple procedure, based on rapid and safe operations, may represent a useful tool in the routine analysis of pyrethroids pesticides, in the place of the currently used conventional techniques.  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