全文获取类型
收费全文 | 2194篇 |
免费 | 60篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 29篇 |
综合类 | 2篇 |
化学工业 | 473篇 |
金属工艺 | 88篇 |
机械仪表 | 45篇 |
建筑科学 | 32篇 |
矿业工程 | 1篇 |
能源动力 | 137篇 |
轻工业 | 110篇 |
水利工程 | 17篇 |
石油天然气 | 8篇 |
无线电 | 301篇 |
一般工业技术 | 445篇 |
冶金工业 | 221篇 |
原子能技术 | 25篇 |
自动化技术 | 323篇 |
出版年
2023年 | 15篇 |
2022年 | 28篇 |
2021年 | 39篇 |
2020年 | 20篇 |
2019年 | 40篇 |
2018年 | 53篇 |
2017年 | 41篇 |
2016年 | 54篇 |
2015年 | 41篇 |
2014年 | 53篇 |
2013年 | 127篇 |
2012年 | 86篇 |
2011年 | 119篇 |
2010年 | 106篇 |
2009年 | 93篇 |
2008年 | 95篇 |
2007年 | 96篇 |
2006年 | 83篇 |
2005年 | 66篇 |
2004年 | 49篇 |
2003年 | 50篇 |
2002年 | 50篇 |
2001年 | 40篇 |
2000年 | 38篇 |
1999年 | 46篇 |
1998年 | 79篇 |
1997年 | 67篇 |
1996年 | 45篇 |
1995年 | 45篇 |
1994年 | 46篇 |
1993年 | 32篇 |
1992年 | 43篇 |
1991年 | 41篇 |
1990年 | 26篇 |
1989年 | 30篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 12篇 |
1985年 | 22篇 |
1984年 | 22篇 |
1983年 | 28篇 |
1982年 | 27篇 |
1981年 | 21篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 10篇 |
1977年 | 16篇 |
1975年 | 13篇 |
1974年 | 11篇 |
1973年 | 11篇 |
排序方式: 共有2257条查询结果,搜索用时 15 毫秒
991.
In this paper, a generic asynchronous First In First Out (FIFO) based WISHBONE compatible plug and play Network Interface (NI) for Network on Chip (NoC) is designed and verified. Four different types of encoded asynchronous FIFOs namely binary, Gray, one-hot and Johnson are designed and analyzed. It is found that Gray-code asynchronous FIFO is the best to handle the asynchronous clock domain issues in NI. The control signals of the WISHBONE bus wrappers from/to asynchronous FIFOs and packing/unpacking modules are asserted concurrently at the same rising edge of the respective router and IP clocks to reduce the latency. The same NI has been utilized for transferring data between synchronous as well as asynchronous clock domains irrespective of clock frequency and phase differences. The proposed NI ensures the seamless high data throughput between the routers and IP cores with minimal latency, higher throughput, higher speed and utilized lesser area compared to the existing design. 相似文献
992.
In today's competitive business climate characterized by uncertain oil markets, responding effectively and speedily to market forces, while maintaining reliable operations, is crucial to a refinery's bottom line. Optimal crude oil scheduling enables cost reduction by using cheaper crudes intelligently, minimizing crude changeovers, and avoiding ship demurrage. So far, only discrete-time formulations have stood up to the challenge of this important, nonlinear problem. A continuous-time formulation would portend numerous advantages, however, existing work in this area has just begun to scratch the surface. In this paper, we present the first complete continuous-time mixed integer linear programming (MILP) formulation for the short-term scheduling of operations in a refinery that receives crude from very large crude carriers via a high-volume single buoy mooring pipeline. This novel formulation accounts for real-world operational practices. We use an iterative algorithm to eliminate the crude composition discrepancy that has proven to be the Achilles heel for existing formulations. While it does not guarantee global optimality, the algorithm needs only MILP solutions and obtains excellent maximum-profit schedules for industrial problems with up to 7 days of scheduling horizon. We also report the first comparison of discrete- vs. continuous-time formulations for this complex problem. 相似文献
993.
We investigate optimal pricing and capacity planning decisions for product-line settings such as introducing a new product or dropping an existing one. We consider a two-product, two-period model with stochastic demands, where price and capacity decisions are made at the outset. Investment in capacity must be traded-off against the possibility of buying at higher spot market prices due to shortage in capacity or charging a higher price to manage the demand. Prior studies argue that introducing an additional product to the product-line strains capacity, resulting in an increase in the price of an existing product. In contrast, we find that introducing a new product can also result in a drop in price of an existing product, enabling strategic pricing by firms. The necessary condition for this to occur is that the demand uncertainties for the products are of similar magnitude and negatively correlated. Similar insights are obtained for the setting where an existing product is dropped from the product-line. Hence, product-market decisions and contextual factors play a role in capacity planning, capacity cost allocation and pricing. 相似文献
994.
Dose‐Dependent Therapeutic Distinction between Active and Passive Targeting Revealed Using Transferrin‐Coated PGMA Nanoparticles
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ruhani Singh Marck Norret Michael J. House Yuriy Galabura Michael Bradshaw Diwei Ho Robert C. Woodward Timothy G. St. Pierre Igor Luzinov Nicole M. Smith Lee Yong Lim Killugudi Swaminathan Iyer 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(3):351-359
The paradigm of using nanoparticle‐based formulations for drug delivery relies on their enhanced passive accumulation in the tumor interstitium. Nanoparticles with active targeting capabilities attempt to further enhance specific delivery of drugs to the tumors via interaction with overexpressed cellular receptors. Consequently, it is widely accepted that drug delivery using actively targeted nanoparticles maximizes the therapeutic benefit and minimizes the off‐target effects. However, the process of nanoparticle mediated active targeting initially relies on their passive accumulation in tumors. In this article, it is demonstrated that these two tumor‐targeted drug delivery mechanisms are interrelated and dosage dependent. It is reported that at lower doses, actively targeted nanoparticles have distinctly higher efficacy in tumor inhibition than their passively targeted counterparts. However, the enhanced permeability and retention effect of the tumor tissue becomes the dominant factor influencing the efficacy of both passively and actively targeted nanoparticles when they are administered at higher doses. Importantly, it is demonstrated that dosage is a pivotal parameter that needs to be taken into account in the assessment of nanoparticle mediated targeted drug delivery. 相似文献
995.
SS George S Swaminathan AS Kanagasabapathy L Seshadri 《Canadian Metallurgical Quarterly》1998,11(3):120-121
Recent studies have shown that the persistence of the cavum septi pellucidi beyond the neonatal period is a marker of cerebral dysgenesis. It has been suggested that the finding of a persistent cavum vergae is also a marker of disturbed brain development. In order to investigate this hypothesis we reviewed 161 brain magnetic resonance imaging scans from normal individuals for the presence of cavum septi pellucidi or cavum vergae, or both. In the 34 prospectively obtained normal adults, there were no individuals with either a cavum septi pellucidi or cavum vergae. In the "defined" normal subjects 3 of 127 individuals (2.4%) had a cavum septi pellucidi whereas a cavum vergae was noted in 26 of 127 (20.5%). We next reviewed the neuroimaging studies of 249 children and adults evaluated for mental retardation or developmental delay. A cavum septi pellucidi was found in 38 of 249 (15.3%) and a cavum vergae in 48 of 249 (19.3%) of these patients. A cavum septi pellucidi and cavum vergae were found together in 19 of 249 (7.6%). We interpret these data as showing that the cavum septi pellucidi is rarely seen in normal individuals although the cavum vergae is seen with the same frequency in normal and retarded populations. Thus we conclude that the cavum septi pellucidi serves as a significant marker of cerebral dysfunction manifested by neurodevelopmental abnormalities while the cavum vergae alone does not identify individuals at risk for cognitive delays. 相似文献
996.
A new, to our knowledge, interferometric method of measuring beatlengths in polarization-maintaining fibers that is based on correlationmeasurements is presented. 相似文献
997.
Quentin Avril Donya Ghafourzadeh Srinivasan Ramachandran Sahel Fallahdoust Sarah Ribet Olivier Dionne Martin de Lasa Eric Paquette 《Computer Graphics Forum》2016,35(2):115-126
We present a general method for transferring skeletons and skinning weights between characters with distinct mesh topologies. Our pipeline takes as inputs a source character rig (consisting of a mesh, a transformation hierarchy of joints, and skinning weights) and a target character mesh. From these inputs, we compute joint locations and orientations that embed the source skeleton in the target mesh, as well as skinning weights to bind the target geometry to the new skeleton. Our method consists of two key steps. We first compute the geometric correspondence between source and target meshes using a semi‐automatic method relying on a set of markers. The resulting geometric correspondence is then used to formulate attribute transfer as an energy minimization and filtering problem. We demonstrate our approach on a variety of source and target bipedal characters, varying in mesh topology and morphology. Several examples demonstrate that the target characters behave well when animated with either forward or inverse kinematics. Via these examples, we show that our method preserves subtle artistic variations; spatial relationships between geometry and joints, as well as skinning weight details, are accurately maintained. Our proposed pipeline opens up many exciting possibilities to quickly animate novel characters by reusing existing production assets. 相似文献
998.
ABSTRACTMuch of the research on climate change adaptation in rapidly urbanizing developing regions focuses primarily on adaptation or resilience as the goal, assumes that climate change is the major stressor, and focuses on the household or the city as the unit of analysis. In this article, we use findings from two rapidly urbanizing sub-basins of the Cauvery River in southern India (the Arkavathy and Noyyal sub-basins) to argue for a broader analytic and policy framework that explicitly considers multiple normative concerns and stressors, and uses the entire watershed as the unit of analysis to address the climate–water interaction. 相似文献
999.
Modified algorithms for synthesizing high-frequency rules from different data sources 总被引:1,自引:1,他引:0
Thirunavukkarasu Ramkumar Rengaramanujam Srinivasan 《Knowledge and Information Systems》2008,17(3):313-334
Because of the rapid growth in information and communication technologies, a company’s data may be spread over several continents.
For an effective decision-making process, knowledge workers need data, which may be geographically spread in different locations.
In such circumstances, multi-database mining plays a major role in the process of extracting knowledge from different data
sources. In this paper, we have proposed a new methodology for synthesizing high-frequency rules from different data sources,
where data source weight has been calculated on the basis of their transaction population. We have also proposed a new method
for calculating global confidence. Our goal in synthesizing local patterns to obtain global patterns is that, the support
and confidence of synthesized patterns must be very nearly same if all the databases are integrated and mono-mining has been
done. Experiments conducted clearly establish that the proposed method of synthesizing high-frequency rules fairly meets the
stipulation.
相似文献
Rengaramanujam Srinivasan (Corresponding author)Email: |
1000.
Katherine R. Merriman Prasad Daggupati Raghavan Srinivasan Brett Hayhurst 《Journal of Great Lakes research》2019,45(3):619-641
The Great Lakes “Priority Watershed” effort targeted the Upper East River watershed, a 116.5-km2 tributary watershed to Wisconsin's Green Bay, to reduce its sediment and nutrients loads from agricultural sources. A Soil and Water Assessment Tool (SWAT) model was created to determine the effectiveness of agricultural Best Management Practices (BMPs) funded through the Great Lakes Restoration Initiative. The model was calibrated at the monthly time-step for flow, sediment, dissolved reactive phosphorus (DRP), total phosphorus (TP), nitrate, and total nitrogen (TN). Field- and watershed-scale sediment and nutrient reductions were calculated due to the implementation of 74 BMP combinations on dairy and cash grain rotations. Modeling results indicated that when multiple BMPs were placed on a field, especially those including filter strips and grassed waterways, sediment and nutrient loads generally were reduced more than single BMP implementation. The most effective in-field practice at reducing DRP and TP on dairy fields was a combination of 5 different BMPs: cover crops, crop rotation, nutrient management plan, reduced tillage, and a filter strip. Conservation cover was the single most effective practice at reducing sediment and nutrient yields. Sediment and nutrient loads decreased at the watershed scale as the quantity and coverage of BMPs increased. When all contracted BMPs were simulated at the watershed scale, sediment loads were reduced 2%, while TP, DRP, TN and nitrate loads were reduced 20%, 9%, 24%, and 17%, respectively. Modeling scenarios also indicated that over-winter manure storage was important to keep soluble nutrients out of waterways. 相似文献