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   262篇
  免费   22篇
电工技术   4篇
综合类   4篇
化学工业   85篇
金属工艺   3篇
机械仪表   7篇
建筑科学   24篇
能源动力   6篇
轻工业   46篇
水利工程   1篇
无线电   12篇
一般工业技术   41篇
冶金工业   18篇
原子能技术   5篇
自动化技术   28篇
  2023年   4篇
  2022年   6篇
  2021年   22篇
  2020年   12篇
  2019年   8篇
  2018年   2篇
  2017年   15篇
  2016年   7篇
  2015年   14篇
  2014年   8篇
  2013年   23篇
  2012年   11篇
  2011年   17篇
  2010年   10篇
  2009年   9篇
  2008年   14篇
  2007年   8篇
  2006年   11篇
  2005年   7篇
  2004年   8篇
  2003年   10篇
  2002年   12篇
  2001年   6篇
  2000年   5篇
  1999年   3篇
  1998年   4篇
  1997年   2篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1990年   3篇
  1989年   3篇
  1987年   3篇
  1986年   2篇
  1985年   1篇
  1981年   2篇
  1978年   1篇
  1976年   2篇
排序方式: 共有284条查询结果,搜索用时 625 毫秒
71.
Production of printable enzymatic power sources was scaled up from laboratory to roll-to-roll (R2R) pilot production. The anode and cathode enzymes were glucose oxidase (GOx) and laccase, respectively. The best laboratory-scale cells had a maximum power and energy density of 1.4 ± 0.1 µW cm?2 and 5.5 ± 0.2 µWh cm?2, respectively. These values are 5 and 28 times higher compared to our previously published values. The R2R-produced cells had a maximum power and energy density of 0.40 ± 0.03 µW cm?2 and 0.6 ± 0.1 µWh cm?2, respectively. This is 11 % of the best laboratory manufactured cells. It is suspected that the decrease in electrochemical performance originates from the lower mediator amount and higher drying temperature than that of the laboratory produced cells. However, the trials conducted in this work showed that printed enzymatic active layers can be fabricated and dried with a rotary screen-printing machine in R2R process. Hence, fully printed GOx//laccase power sources could be produced from R2R on a large scale for printed electronics applications.  相似文献   
72.
The purpose of this study is to assemble information of costs per fatal casualty in traffic accidents, adopted by authorities in different countries. analyse and compare these figures as well as the methods used for estimating these values. A questionnaire was sent to 19 countries from which 11 gave information on cost per fatality and methods of valuation. The costs per fatality, usually defined as direct and indirect costs plus a value of safety per se, are compared both between countries and over time, 1990 and 1999, for each country. The average cost per fatality has increased between 1990 and 1999 (fixed prices) due to both changes in the methodology and changes of valuations. Great Britain, New Zealand, Sweden and the US conduct own willingness-to-pay (WTP) surveys, while the Netherlands and Norway make reviews of these studies. In Finland, the cost per fatality is a combination of the value of lost productivity and the cost of care for an institutionalised disabled person. In Australia, Austria, Germany and Switzerland, the cost per fatality is estimated as a value of lost productivity and an addition of a human cost based on compensation payments or insurance payments. Estimates from recently conducted WTP surveys or meta-analyses are considered in Austria, Finland and Sweden, however, not yet adopted as official values for use in road traffic planning.  相似文献   
73.
Herein, we fabricate hollow silica nanoparticles with exceptionally narrow size distributions that inherently possess two distinct length scales—tens of nanometers with regards to the shell thickness, and hundreds of nanometers in regards to the total diameter. We characterize these structures using dynamic and static light scattering (DLS and SLS), small angle X-ray scattering (SAXS), and transmission electron microscopy (TEM), and we demonstrate quantitative agreement among all methods. The ratio between the radius of gyration (SLS) and hydrodynamic radius (DLS) in these particles equals almost unity, corresponding to ideal capsule behavior. We are able to resolve up to 20 diffraction orders of the hollow sphere form factor in SAXS, indicating a narrow size distribution. Data from light and X-ray scattering can be combined to a master curve covering a q-range of four orders of magnitude assessing all hierarchical length scales of the form factor. The measured SLS intensity profiles noticeably change when the scattering contrast between the interior and exterior is altered, whereas the SAXS intensity profiles do not show any significant change. Tight control of the aforementioned length scales in one simple and robust colloidal building block renders these particles suitable as future calibration standards.
  相似文献   
74.
Mariagrazia  Maria Pia  Agostino Marcello  Walter   《Automatica》2009,45(11):2665-2672
The paper addresses the fault detection problem for discrete event systems in a Petri Net (PN) framework. Assuming that the structure of the PN model and the initial marking are known, faults are modelled by unobservable transitions. Moreover, we assume that there may be additional unobservable transitions associated with the system legal behaviour and that the marking reached after the firing of any transition is unknown. The proposed diagnoser works on-line: it waits for the firing of an observable transition and employs an algorithm based on the definition and solution of some integer linear programming problems to decide whether the system behaviour is normal or exhibits some possible faults. The results characterize the properties that the PN modelling the system fault behaviour has to fulfill in order to reduce the on-line computational effort.  相似文献   
75.
The paper addresses the optimal design of the last supply chain branch, i.e., the Distribution Network (DN), starting from manufacturers till the retailers. It considers a distributed system composed of different stages connected by material links labeled with suitable performance indices. A hierarchical procedure employing direct graph (digraph) modeling, mixed integer linear programming, and the Analytic Hierarchy Process (AHP) is presented to select the optimal DN configuration. More in detail, a first-level DN optimization problem taking into account the definition and evaluation of the distribution chain performance provides a set of Pareto optimal solutions defined by digraph modeling. A second level DN optimization using the AHP method selects, on the basis of further criteria, the DN configuration from the Pareto face alternatives. To show the method effectiveness, the optimization model is applied to a case study describing an Italian regional healthcare drug DN. The problem solution by the proposed design method allows improving the DN flexibility and performance.  相似文献   
76.
Little is known on both the composition and mechanism(s) of proteinuria associated with the use of mTOR inhibitors, in particular of Everolimus (E). We characterized urinary proteins utilizing an integrated proteomics approach (quantitative essays, 2‐DE, MALDI‐TOF, Western blot) in 48 renal transplant recipients who were alternatively treated with E (n = 31) or with enteric coated mycophenolic acid (EC‐MPA) (n = 17). Twelve E patients (39%) developed high (>3 g/day) or intermediate proteinuria (1–3 g) compared to four (23%) of the EC‐MPA group. Urinary proteins (p<0.001), β2 microglobulin (p<0.001) and α1microglobulin (p<0.025) were higher in E than in EC‐MPA, appeared more rapidly and were inversely correlated with the day of treatment. Proteomics showed a marked increase of all urinary components in E and EC‐MPA patients, major changes involving typical components of glomerular damage (albumin, α1‐Zn glycoprotein, α2HS glycoprotein, leucin‐richα2‐glycoprotein) and specific bio‐markers for E (clusters of α1‐antitrypsin fragments and monoclonal λ chains). Finally, inter‐α‐trypsin‐inhibitor heavy chain H4 precursor was decreased in E and EC‐MPA urine compared to normal urine. In conclusion, E induced massive and generalized proteinuria of mixed glomerular and tubular origin that was correlated with the start of treatment and reached a nephrotic range in few cases. Specific urinary markers reflect renal alterations related to the transplant or specific alterations associated with the drug.  相似文献   
77.
The Coster–Kronig enhancement factor calculation for M3M3 shell x-ray production cross sections was found to be incorrect in both ISICSoo class (Bati? et al. (2012) [1]) and isics program (Cipolla (2013) [2]). The affected functions of ISICSoo class have been corrected. The resulting X-ray production cross sections are modified by less than 15%, while ionization cross sections are unchanged.  相似文献   
78.
Proteolysis is a key event in several biological processes; proteolysis must be tightly controlled because its improper activation leads to dramatic consequences. Deregulation of proteolytic activity characterizes many pathological conditions, including cancer. The plasminogen activation (PA) system plays a key role in cancer; it includes the serine-protease urokinase-type plasminogen activator (uPA). uPA binds to a specific cellular receptor (uPAR), which concentrates proteolytic activity at the cell surface, thus supporting cell migration. However, a large body of evidence clearly showed uPAR involvement in the biology of cancer cell independently of the proteolytic activity of its ligand. In this review we will first describe this multifunctional molecule and then we will discuss how uPAR can sustain most of cancer hallmarks, which represent the biological capabilities acquired during the multistep cancer development. Finally, we will illustrate the main data available in the literature on uPAR as a cancer biomarker and a molecular target in anti-cancer therapy.  相似文献   
79.
This article traces the evolution of the right to data protection in European law, with a particular focus on the inclusion of the right in the European Union Charter of Fundamental Rights and its proposed legal status under the new Constitutional Treaty. In particular, the discussion considers the legal impact of this 'constitutionalisation' of this area of legal protection. It is argued that this should be viewed as more than just a formal development in that entrenchment of the right may strengthen ground-level interpretation and implementation of data protection principles.  相似文献   
80.
Identifiability is a fundamental prerequisite for model identification; it concerns uniqueness of the model parameters determined from the input-output data, under ideal conditions of noise-free observations and error-free model structure. In the late 1980s concepts of differential algebra have been introduced in control and system theory. Recently, differential algebra tools have been applied to study the identifiability of dynamic systems described by polynomial equations. These methods all exploit the characteristic set of the differential ideal generated by the polynomials defining the system. In this paper, it will be shown that the identifiability test procedures based on differential algebra may fail for systems which are started at specific initial conditions and that this problem is strictly related to the accessibility of the system from the given initial conditions. In particular, when the system is not accessible from the given initial conditions, the ideal I having as generators the polynomials defining the dynamic system may not correctly describe the manifold of the solution. In this case a new ideal that includes all differential polynomials vanishing at the solution of the dynamic system started from the initial conditions should be calculated. An identifiability test is proposed which works, under certain technical hypothesis, also for systems with specific initial conditions.  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