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61.
该试验比较了不同混合物,尿素-重过磷酸钙-氯化钾、尿素-重过磷酸钙-氯化钾-腐植酸、尿素-重过磷酸钙-氯化钾-黄腐酸、尿素-重过磷酸钙-氯化钾-酸性混合物(黄腐酸+腐植酸)在对氨损失,土壤pH值,铵态氮和可利用硝态氮积累等方面的影响,以尿素单独施用作为对照。方法:在实验室条件下,利用一个封闭式动态空气流量系统来评估是否混有重过磷酸钙、氯化钾、腐植酸、黄腐酸的情况下尿素的有效性。氨损失、土壤pH值、土壤中铵态氮以及可利用硝态氮是由标准程序测定的。结果:与对照组(单独施用尿素)相比,处理尿素-重过磷酸钙-氯化钾,尿素-重过磷酸钙-氯化钾-腐植酸,尿素-重过磷酸钙-氯化钾-黄腐酸,尿素-重过磷酸钙-氯化钾-酸性混合物(黄腐酸+腐植酸)中氨损失明显地减少,减少率由12.92%、20.12%、25.94%达到100%,土壤中的铵态氮也有类似的变化。从所有的处理来看,只有尿素-重过磷酸钙-氯化钾-黄腐酸,尿素-重过磷酸钙-氯化钾-酸性混合物(腐植酸+黄腐酸)明显地积累了土壤中可利用硝态氮,这一结果与本研究中pH值的结果一致。结论:尿素、重过磷酸钙、氯化钾中混合腐植酸或者酸性的腐植酸和黄腐酸混合物能够显著减少氨损失。这项研究结果有助于提高尿素中N,P,K使用的有效性,同时减少环境污染。 相似文献
62.
Nikša Tadić Artur Marchlewski Horst Zimmermann 《Analog Integrated Circuits and Signal Processing》2009,61(1):19-33
An optical sensor front-end with integrated PIN photodiode in 0.6 μm BiCMOS technology intended for universal optical storage
operation is presented. It is based on a mixed current conveyor and voltage amplifiers topology avoiding stability problems.
The transimpedance is continuously variable and directly proportional to a voltage-controlled resistance. Another voltage-controlled
resistor within a variable-gain voltage amplifier increases the photo-sensitivity range. A fixed-gain voltage amplifier and
a current biasing of the current conveyor enable frequency bandwidth enhancement leading to a large transimpedance bandwidth
product. A linearity error smaller than 2.8%, a photo-sensitivity range of 541 (54.7 dB) with the largest photo-sensitivity
of 2468 mV/μW, an offset voltage <13.7 mV, a frequency bandwidth up to 277 MHz, a slew rate up to 377 V/μs, a transimpedance
bandwidth product up to 122 TΩ Hz, and a maximum power consumption of <4.3 mW are achieved. 相似文献
63.
Curtin CM Cunniffe GM Lyons FG Bessho K Dickson GR Duffy GP O'Brien FJ 《Advanced materials (Deerfield Beach, Fla.)》2012,24(6):749-754
The ability of nano-hydroxyapatite (nHA) particles developed in-house to act as non-viral delivery vectors is assessed. These nHA particles are combined with collagen to yield bioactive, biodegradable collagen nano-hydroxyapatite (coll-nHA) scaffolds. Their ability to act as gene-activated matrices for BMP2 delivery is demonstrated with successful transfection of mesenchymal stem cells (MSCs) resulting in high calcium production. 相似文献
64.
Steven C. Rogers Connor Barickman Greg Chavoor Matt Kinni Nik Glazar Peter V. Schwartz 《Solar Energy》2012,86(1):132-138
Using a combination of custom computer code and commercially available ray-tracing software, we explore variations of concentrator geometries where sunlight is first incident onto a stationary primary mirror of circular cross section. The reflected radiation is incident onto a smaller, secondary moveable mirror, which focuses the radiation onto a stationary target. Simulations for this trough geometry show peak concentrations of 38 solar equivalents. 相似文献
65.
Many epidemiological models for plant disease include host demography to describe changes in the availability of susceptible tissue for infection. We compare the effects of using two commonly used formulations for host growth, one linear and the other nonlinear, upon the outcomes for invasion, persistence and control of pathogens in a widely used, generic model for botanical epidemics. The criterion for invasion, reflected in the basic reproductive number, R0, is unaffected by host demography: R0 is simply a function of epidemiological parameters alone. When, however, host growth is intrinsically nonlinear, unexpected results arise for persistence and the control of disease. The endemic level of infection (I∞) also depends upon R0. We show, however, that the sensitivity of I∞ to changes in R0 > 1 depends upon which underlying epidemiological parameter is changed. Increasing R0 by shortening the infectious period results in a monotonic increase in I∞. If, however, an increase in R0 is driven by increases in transmission rates or by decreases in the decay of free-living inoculum, I∞ first increases (R0 < 2), but then decreases (R0 > 2). This counterintuitive result means that increasing the intensity of control can result in more endemic infection. 相似文献
66.
This study investigated job demands and job control as predictors of safety citizenship role definition, that is, employees' role orientation toward improving workplace safety. Data from a survey of 334 trackside workers were framed in the context of R. A. Karasek's (1979) job demands-control model. High job demands were negatively related to safety citizenship role definition, whereas high job control was positively related to this construct. Safety citizenship role definition of employees with high job control was buffered from the influence of high job demands, unlike that of employees with low job control, for whom high job demands were related to lower levels of the construct. Employees facing both high job demands and low job control were less likely than other employees to view improving safety as part of their role orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
67.
Nik Bessis Ye Huang Peter Norrington Antony Brown Pierre Kuonen Beat Hirsbrunner 《Simulation Modelling Practice and Theory》2011,19(1):5-16
For decades, much work has been done to increase the effectiveness and efficiency of job sharing amongst available computational resources. Resources can be organized into a variety of topologies, and recent work has shown that a decentralized distributed resource topology is a crucial but complicated scenario. This is because decentralized resources are normally grouped into independent virtual organizations (VOs) and isolated from each other by VO boundaries.To convey jobs across gaps between various virtual organizations, a novel resource topology called the self-led critical friend model (CFM) is proposed in this work. The CFM deals with trust credits between resources according to their historical collaboration records. This trust reveals a feasible, realistic, and transferable correlation to facilitate the resource selection process for job delegation between arbitrarily connected physical resources. Consequently, the CFM is able to overcome the constraints caused by virtual organization boundaries.Besides the theoretical model, a simulation-based implementation is carried out together with a complementary high-level community-aware scheduling protocol. After evaluating a number of compositional scenarios and criteria objectives, the observed results show the benefit of job scheduling across multiple VOs, as well as the capability of the self-led critical friend model as a novel cross-VO resource topology to represent and interconnect resources. 相似文献
68.
Sahena Ferdosh Md Zaidul Islam Sarker Nik Norulaini Nik Ab Rahman Md Jahurul Haque Akand Kashif Ghafoor Mohamed Bin Awang Mohd Omar Ab Kadir 《Korean Journal of Chemical Engineering》2013,30(7):1466-1472
Total oil was extracted from ground fish head of Longtail tuna (Thunnus tonggol) using supercritical carbon dioxide (SC-CO2) at 20 to 40 MPa, 45 to 65 °C and 1 to 3 ml min?1. Response surface methodology (RSM) was employed to optimize the operating conditions of the SC-CO2 technique where the highest oil yield was obtained (35.6% on dry weight basis) at 40 MPa, 65 °C, and 3 ml min?1. The solubility of the oil in SC-CO2 increased from 2.9 to 14.2 g oil/100 g of CO2 with increasing pressure and temperature. The total saturated, monounsaturated and polyunsaturated fatty acids obtained were 41.6, 24.7 and 26.8%, respectively, where the omega-3 fatty acids were found to be 22.3%. A correlation was developed determining the coefficients of the second-order polynomial equation where the extraction parameters of SC-CO2 method to extract fish oil from fish sample were successfully optimized using response surface methodology. 相似文献
69.
Townend Paul Huai Jinpeng Xu Jie Looker Nik Zhang Dacheng Li Jianxin Zhong Liang 《Computer》2008,41(8):30-38
A proposed grid middleware system includes specific enhancements to support the development and assessment of highly secure, dependable, service-oriented grid systems and applications. 相似文献
70.
Marek P. Michalowski Selma Šabanović Carl DiSalvo Didac Busquets Laura M. Hiatt Nik A. Melchior Reid Simmons 《Autonomous Robots》2007,22(4):385-397
This paper presents a robot search task (social tag) that uses social interaction, in the form of asking for help, as an integral component of task completion. Socially distributed perception is defined as a robot's ability to augment its limited sensory capacities through social interaction. We describe the task
of social tag and its implementation on the robot GRACE for the AAAI 2005 Mobile Robot Competition & Exhibition. We then discuss
our observations and analyses of GRACE's performance as a situated interaction with conference participants. Our results suggest
we were successful in promoting a form of social interaction that allowed people to help the robot achieve its goal. Furthermore,
we found that different social uses of the physical space had an effect on the nature of the interaction. Finally, we discuss
the implications of this design approach for effective and compelling human-robot interaction, considering its relationship
to concepts such as dependency, mixed initiative, and socially distributed cognition.
An erratum to this article can be found at
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