全文获取类型
收费全文 | 866篇 |
免费 | 33篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 15篇 |
综合类 | 2篇 |
化学工业 | 146篇 |
金属工艺 | 19篇 |
机械仪表 | 30篇 |
建筑科学 | 21篇 |
矿业工程 | 1篇 |
能源动力 | 78篇 |
轻工业 | 50篇 |
水利工程 | 6篇 |
石油天然气 | 9篇 |
无线电 | 120篇 |
一般工业技术 | 157篇 |
冶金工业 | 71篇 |
原子能技术 | 6篇 |
自动化技术 | 173篇 |
出版年
2023年 | 7篇 |
2022年 | 21篇 |
2021年 | 45篇 |
2020年 | 30篇 |
2019年 | 48篇 |
2018年 | 33篇 |
2017年 | 47篇 |
2016年 | 37篇 |
2015年 | 22篇 |
2014年 | 47篇 |
2013年 | 76篇 |
2012年 | 40篇 |
2011年 | 52篇 |
2010年 | 49篇 |
2009年 | 35篇 |
2008年 | 19篇 |
2007年 | 23篇 |
2006年 | 22篇 |
2005年 | 20篇 |
2004年 | 17篇 |
2003年 | 18篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 25篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1995年 | 20篇 |
1994年 | 10篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有904条查询结果,搜索用时 15 毫秒
51.
Jeremy M. Rathfon Zoha M. AL‐Badri Raja Shunmugam Scott M. Berry Santosh Pabba Robert S. Keynton Robert W. Cohn Gregory N. Tew 《Advanced functional materials》2009,19(5):689-695
The chemical sensing of nerve gas agents has become an increasingly important goal due to the 1995 terrorist attack in a Tokyo subway as well as national security concerns in regard to world affairs. Chemical detection needs to be sensitive and selective while being facile, portable, and timely. In this paper, a sensing approach using a pyrene imine molecule is presented that is fluorimetric in response. The detection of a chloro‐Sarin surrogate is measured at 5 ppmv in less than 1 second and is highly selective towards halogenated organophosphates. The pyrene imine molecule is incorporated into polystyrene films as well as micrometer and sub‐micrometer fibers. Using both a direct drawing approach and electrospinning, micrometer and nanofibers can be easily manufactured. Applications for functional sensing micrometer and nanofibers are envisioned for optical devices and photonics in addition to solution and airflow sensing devices. 相似文献
52.
Sekiguchi K. Seki Y. Okitani N. Fukuda M. Critchley S. Habib W.G. Hartman D. Shaw K. 《Industry Applications, IEEE Transactions on》1996,32(3):608-616
The new coupled pickle line and cold mill (CPCM) has been processing steel since December 1991 at Dofasco Inc. in Hamilton, Ontario, Canada. This mill rolls both sheet and tin plate. The work rolls for the last stand are often textured by grit blasting to roll “matte” finished strip. A new computer-targeted control system was developed for the roll speeds and gaps, specifically for matte rolling. The new set-up system uses Stone's model, which is more appropriate for the limited reductions evident with the rougher rolls. Conventional automatic gauge control (AGC) systems using thickness measurements after the last stand are limited in performance by the effect of long transport delays. These limitations are particularly critical during mill acceleration and deceleration. The use of a thickness gauge before the stand with matte rolls allows the development of AGC systems using shorter control loops for final gauge control. The AGC system uses a Smith predictor for transport lag, (phase shift), and compensation. The combination of the shorter AGC loop and the Smith predictor allows higher gains to be used in the control system. This set-up and control system has contributed to Dofasco's position as a market leader in thickness performance 相似文献
53.
54.
P Ambrosi G Habib R Gélisse J Yao A Ferracci B Kreitmann D Métras P Bernard G Bouvenot R Luccioni 《Canadian Metallurgical Quarterly》1998,47(5):334-339
Side effects of morphine are common when given in titrated doses to control severe pain in advanced cancer. We report a case series of acutely ill cancer patients suffering from pain, complications of advanced disease, and opioid side effects. They were treated with intravenous (i.v.) ketorolac along with i.v. morphine using repeated dosing. Excellent pain relief with improvement in the opioid bowel syndrome was achieved. We found it possible to switch from IV ketorolac to oral ketorolac along with oral morphine for long-term pain control. Ketorolac can be well tolerated in high-dose, long-term use even in this frail patient population. An algorithm is presented for the suggested use of ketorolac as a morphine sparing agent. Potential methods for studying ketorolac further in this role are discussed. 相似文献
55.
Antibodies raised against the 51C/SHIP2 inositol polyphosphate 5'-phosphatase were used to examine the effects of growth factors and insulin on the metabolism of this protein. Immunoblot analysis revealed that the 51C/SHIP2 protein was widely expressed in fibroblast and nonhematopoietic tumor cell lines, unlike the SHIP protein, which was found only in cell lines of hematopoietic origin. The 51C/SHIP2 antiserum precipitated a protein of approximately 145 kDa along with an activity which hydrolyzed phosphatidylinositol 3,4, 5-trisphosphate to phosphatidylinositol 3,4-bisphosphate. Tyrosine phosphorylation of the 51C/SHIP2 protein occurred in response to treatment of cells with epidermal growth (EGF), platelet-derived growth factor (PDGF), nerve growth factor (NGF), insulin-like growth factor-1 (IGF-1), or insulin. EGF and PDGF induced transient tyrosine phosphorylation of 51C/SHIP2, with maximal tyrosine phosphorylation occurring at 5-10 min following treatment and returning to near basal levels within 20 min. In contrast, treatment of cells with NGF, IGF-1, or insulin resulted in prolonged tyrosine phosphorylation of 51C/SHIP2 protein, with 40-80% maximal phosphorylation sustained for up to 2 h following agonist treatment. The kinetics of activation of the Akt/PKB protein kinase by the various factors correlated well with the kinetics of tyrosine phosphorylation of 51C/SHIP2. EGF, NGF, and PDGF stimulated the association of 51C/SHIP2 protein with the Shc adapter protein; however, no Shc could be detected in 51C/SHIP2-immune precipitates from cells treated with IGF-1 or insulin. The data suggest that 51C/SHIP2 may play a significant role in regulation of phosphatidylinositol 3'-kinase signaling by growth factors and insulin. 相似文献
56.
Hamam H 《Applied optics》2003,42(35):7052-7059
The fractional Talbot effect brings into play a superimposition of shifted and complex weightedreplicas of the original object. This phenomenon can be used to replicate images of nonperiodic objects by means of Talbot array illuminators. These diffractive elements can also be used to concentrate replicas into a single image. These techniques are useful for several applications such as beam shaping. 相似文献
57.
The paper derives a spiral condition, for a single Pythagorean hodograph quintic transition curve of G2 contact, between two circles with one circle inside the other. A spiral is free of local curvature extrema, making spiral designs an interesting mathematical problem with importance for both physical and aesthetic applications. In the construction of highways or railway routes in particular, it is often desirable to have a transition curve from circle to circle. Here, we treat an open problem on planar quintic spiral segments, called transition curve elements, examine techniques for curve design using the new results, and derive lower and upper bounds for the distance between the two circles. The proposed method is applicable for non-tangent and non-concentric circles. 相似文献
58.
M irghasem Hosseini Habib Ashassi-Sorkhabi Heshmat Allah Yaghobkhani Ghiasvand 《中国稀土学报(英文版)》2007,25(5):537-543
A A cerium-based chemical conversion process was studied. First, zinc coating obtained from a free-cyanide alkaline bath, with derivative of imidazol with new brightener, was investigated, zinc-plated steel specimens were treated with a solution of 50 mmol· L^-1 Ce(NO3 )3 The corrosion behavior of bare and treated mild galvanized steel was evaluated during exposure to 0.5 mol · L^-1 NaCl for different immersion time, using Tafel polarization curves and electrochemical impedance spectroscopy (EIS) measurements. The surface morphology of the coating was studied using scanning electron microscopy (SEM). The composition and chemical percent of the coating were examined by X-ray dispersion energy (EDAX). The results of these measurements showed that the newly developed cerium-based conversion coating process was a promising candidate for replacing the conventional chromate treatments used at present for galvanized steel. 相似文献
59.
There is a real need to develop a sensory system that can monitor and track the behavioral status of a person in real time while protecting his/her privacy. In addition, it is important to have the ability to detect stationary and moving objects in real time to support dynamic navigation needs for mobile robots. This paper describes the development of intelligent fiber-grating (FG)-based 3-D vision sensory system that enables real-time object detection, monitoring, and tracking. This system uses the richness and the strength of the vision while reducing the data load and computational cost by encoding the working space using a limited number of spatially interrelated 2-D laser spots. The sensor system generates the laser spots by projecting a coherent laser beam on two perpendicularly overlaid layers of FGs. The presence of a target within the visible operational view of the sensor disturbs the part of the projected laser spots' pattern where the target appeared. By calculating the displacement of the disturbed spots within the CCD image plane, the sensor system can detect, in a short time, an object/human and provide relevant information in terms of range, approximate shape, and position. To facilitate faster detection and real-time tracking, the author has developed two strategies that decompose the working space into zones and virtual planes 相似文献
60.
Badri Narayan Subudhi Susmita Ghosh Ashish Ghosh 《Machine Vision and Applications》2013,24(4):795-809
Although background subtraction techniques have been used for several years in vision systems for moving object detection, many of them fail to provide good results in presence of noise, illumination variation, non-static background, etc. A basic requirement of background subtraction scheme is the construction of a stable background model and then comparing each incoming image frame with it so as to detect moving objects. The novelty of the proposed scheme is to construct a stable background model from a given video sequence dynamically. The constructed background model is compared with different image frames of the same sequence to detect moving objects. In the proposed scheme the background model is constructed by analyzing a sequence of linearly dependent past image frames in Wronskian framework. The Wronskian based change detection model is further used to detect the changes between the constructed background scene and the considered target frame. The proposed scheme is an integration of Gaussian averaging and Wronskian change detection model. Gaussian averaging uses different modes which arise over time to capture the underlying richness of background, and it is an approach for background building by considering temporal modes. Similarly, Wronskian change detection model uses a spatial region of support in this regard. The proposed scheme relies on spatio-temporal modes arising over time to build the appropriate background model by considering both spatial and temporal modes. The results obtained by the proposed model is found to provide accurate shape of moving objects. The effectiveness of the proposed scheme is verified by comparing the results with those of some of the existing state of the art background subtraction techniques on public benchmark databases. We found that the average F-measure is significantly improved by the proposed scheme from that of the state-of-the-art techniques. 相似文献