全文获取类型
收费全文 | 399篇 |
免费 | 11篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 113篇 |
金属工艺 | 17篇 |
机械仪表 | 10篇 |
建筑科学 | 9篇 |
能源动力 | 13篇 |
轻工业 | 19篇 |
水利工程 | 1篇 |
无线电 | 56篇 |
一般工业技术 | 63篇 |
冶金工业 | 38篇 |
原子能技术 | 2篇 |
自动化技术 | 55篇 |
出版年
2022年 | 5篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 6篇 |
2013年 | 16篇 |
2012年 | 9篇 |
2011年 | 17篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 22篇 |
2007年 | 18篇 |
2006年 | 14篇 |
2005年 | 9篇 |
2004年 | 5篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有410条查询结果,搜索用时 15 毫秒
241.
Suresh S. Pitty Wenkai Li Arief Adhitya Rajagopalan Srinivasan I.A. Karimi 《Computers & Chemical Engineering》2008,32(11):2767-2786
Supply chain studies are increasingly given top priority in enterprise-wide management. Present-day supply chains involve numerous, heterogeneous, geographically distributed entities with varying dynamics, uncertainties, and complexity. The performance of a supply chain relies on the quality of a multitude of design and operational decisions made by the various entities. In this two-part paper, we demonstrate that a dynamic model of an integrated supply chain can serve as a valuable quantitative tool that aids in such decision-making. In this Part 1, we present a dynamic model of an integrated refinery supply chain. The model explicitly considers the various supply chain activities such as crude oil supply and transportation, along with intra-refinery supply chain activities such as procurement planning, scheduling, and operations management. Discrete supply chain activities are integrated along with continuous production through bridging procurement, production, and demand management activities. Stochastic variations in transportation, yields, prices, and operational problems are considered in the proposed model. The economics of the refinery supply chain includes consideration of different crude slates, product prices, operation costs, transportation, etc. The proposed model has been implemented as a dynamic simulator, called Integrated Refinery In-Silico (IRIS). IRIS allows the user the flexibility to modify not only parameters, but also replace different policies and decision-making algorithms in a plug-and-play manner. It thus allows the user to simulate and analyze different policies, configurations, uncertainties, etc., through an easy-to-use graphical interface. The capabilities of IRIS for strategic and tactical decision support are illustrated using several case studies. 相似文献
242.
Arief Adhitya Rajagopalan Srinivasan Iftekhar A. Karimi 《American Institute of Chemical Engineers》2009,55(6):1447-1463
Risk management has become imperative for today's complex supply chains. Most approaches reported in the literature have been ad‐hoc and specific to certain risks; a general and comprehensive approach is lacking. To address this, we present a structured methodology for risk identification. Supply chain networks are in many ways similar to chemical plants, therefore well‐established methods and concepts from chemical process risk management can be adapted to supply chains. Drawing from this analogy, we propose to represent supply chain structure and operations using flow and work‐flow diagrams, equivalent to process flow diagrams (PFDs) and operating procedures. Following the HAZard and OPerability (HAZOP) analysis method common in process safety, risk identification can be performed by systematically generating deviations in different supply chain parameters and identifying their possible causes, consequences, safeguards, and mitigating actions. The application and benefits of the proposed approach are demonstrated using a refinery supply chain case study. © 2009 American Institute of Chemical Engineers AIChE J, 2009 相似文献
243.
The inhibition of Cu2+, Cd2+ and Zn2+ discharge reactions was studied in the presence of C4–C6 alcohols, phenol, benzyl alcohol and cyclohexanol (SAS) in 0.5 M Na2SO4 + 1 mM H2SO4 supporting electrolyte. It is found from the results that at high surface coverages by SAS, the inhibition is due to “sieve effect” which is different from that at low coverages. The true standard rate constant is proportional to exp[(? N ΔγAi)/(RT)] where ΔγAi is the extra energy (in the form of work) that must be done in order to create a free area required for a discharge reaction. 相似文献
244.
A study of the anodic and cathodic reactions involved in the corrosion of iron in phosphoric acid shows that the rate determining steps for the two reactions are similar to those reported for corrosion of iron in sulphuric acid. However, the dependance of icorr and Ecorr on time and solution parameters shows that an additional factor in the corrosion of iron in phosphoric acid is the slow coverage of the iron surface with phosphate resulting in a decrease of corrosion rate with time. 相似文献
245.
Rao B Anderson TA Orris GJ Rainwater KA Rajagopalan S Sandvig RM Scanlon BR Stonestrom DA Walvoord MA Jackson WA 《Environmental science & technology》2007,41(13):4522-4528
A substantial reservoir (up to 1 kg ha(-1)) of natural perchlorate is present in diverse unsaturated zones of the arid and semi-arid southwestern United States. The perchlorate co-occurs with meteoric chloride that has accumulated in these soils throughout the Holocene [0 to 10-15 ka (thousand years ago)] and possibly longer periods. Previously, natural perchlorate widely believed to be limited to the Atacama Desert, now appears widespread in steppe-to-desert ecoregions. The perchlorate reservoir becomes sufficiently large to affect groundwater when recharge from irrigation or climate change flushes accumulated salts from the unsaturated zone. This new source may help explain increasing reports of perchlorate in dry region agricultural products and should be considered when evaluating overall source contributions. 相似文献
246.
Vidya Rajagopalan Vanessa Schmithorst Alexander El-Ali William Reynolds Vincent Lee Julia Wallace Jacqueline Weinberg Jennifer Johnson Jodie Votava-Smith Jennifer Adibi Ashok Panigrahy 《International journal of molecular sciences》2022,23(23)
The relationship between maternal risk factors (MRFs) (particularly pre-gravid obesity, diabetes, and hypertension) and congenital heart disease (CHD) to placental and fetal brain outcomes is poorly understood. Here, we tested the hypothesis that MRF and CHD would be associated with reduced intrinsic placental and fetal brain function using a novel non-invasive technique. Pregnant participants with and without MRF and fetal CHD were prospectively recruited and underwent feto-placental MRI. Using intrinsic properties of blood oxygen level dependent imaging (BOLD) we quantified spatiotemporal variance of placenta and fetal brain. MRFs and CHD were correlated with functional characteristics of the placenta and fetal brain. Co-morbid MRF (hypertension, diabetes, and obesity) reduced spatiotemporal functional variance of placenta and fetal brain (p < 0.05). CHD predicted reduced fetal brain temporal variance compared to non-CHD (p < 0.05). The presence of both MRF and CHD was associated with reduced intrinsic pBOLD temporal variance (p = 0.047). There were no significant interactions of MRFs and CHD status on either temporal or spatial variance of intrinsic brain BOLD. MRF and CHD reduced functional characteristic of placenta and brain in fetuses. MRF modification and management during pregnancy may have the potential to not only provide additional risk stratification but may also improve neurodevelopmental outcomes. 相似文献
247.
248.
249.
250.
Sang-Joon Lee Hak-Lim Kim Jin-Pyung Lee Sundara Rajagopalan 《Journal of Mechanical Science and Technology》2012,26(12):4007-4016
The flow characteristics of jets issued from a sinusoidal nozzle with in-phase and 180° out-of-phase exit configurations were investigated using PIV (particle image velocimetry) and flow visualization techniques. The experiments were carried out at a Reynolds number of about 6300 based on the mean width of the jet nozzle. Compared to a normal rectangular jet, the sinusoidal nozzle jets have smaller velocity deficits as the flow goes downstream. In addition, the turbulence intensity is suppressed in the horizontal center plane. For the case of in-phase wavy nozzle jet, the length of the potential core exhibits small variations along the lateral direction, while the 180° out-of-phase wavy nozzle jet shows large lateral variation in the length of potential core. The turbulent kinetic energy of the 180° out-ofphase nozzle jet also shows sinusoidal variation in the horizontal planes. Large-scale vortices shed from the sinusoidal edge of the nozzle interact strongly and migrate toward the center plane as the flow develops downstream. 相似文献