全文获取类型
收费全文 | 2457篇 |
免费 | 237篇 |
国内免费 | 31篇 |
专业分类
电工技术 | 72篇 |
综合类 | 9篇 |
化学工业 | 852篇 |
金属工艺 | 73篇 |
机械仪表 | 81篇 |
建筑科学 | 88篇 |
矿业工程 | 6篇 |
能源动力 | 135篇 |
轻工业 | 196篇 |
水利工程 | 48篇 |
石油天然气 | 49篇 |
武器工业 | 5篇 |
无线电 | 205篇 |
一般工业技术 | 376篇 |
冶金工业 | 91篇 |
原子能技术 | 9篇 |
自动化技术 | 430篇 |
出版年
2024年 | 9篇 |
2023年 | 41篇 |
2022年 | 63篇 |
2021年 | 171篇 |
2020年 | 136篇 |
2019年 | 180篇 |
2018年 | 237篇 |
2017年 | 220篇 |
2016年 | 193篇 |
2015年 | 113篇 |
2014年 | 200篇 |
2013年 | 277篇 |
2012年 | 193篇 |
2011年 | 211篇 |
2010年 | 114篇 |
2009年 | 104篇 |
2008年 | 68篇 |
2007年 | 45篇 |
2006年 | 46篇 |
2005年 | 17篇 |
2004年 | 11篇 |
2003年 | 15篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有2725条查询结果,搜索用时 359 毫秒
181.
Conventional stereo imaging uses area CCDs for which depth perception error has been analyzed in our past research (Comput. Vision Image understand. 63 (3) (1996) 447). In this work we analyze the depth perception error for a stereo system that uses two rotating linear CCD cameras to create cylindrical stereo images. Theoretical analysis shows certain advantages to cylindrical stereo imaging over conventional methods. Initial experimental results are presented to validate the theoretical results. Unlike normal area CCDs, cylindrical images captured by rotating linear CCD cameras can produce very high-resolution images thereby substantially reducing the error in 3D estimation. 相似文献
182.
Muscle is a highly heterogeneous tissue. Practical approaches to sample selectively small regions of muscle cross sections would help to effectively utilize analytical techniques on muscle studies while taking into account tissue heterogeneity. In this report, semimembranosus muscle tissue cross sections were directly sampled and analyzed by capillary electrophoresis (CE) with laser-induced fluorescence detection (LIF). Prior to CE-LIF analysis, a small region in the muscle cross section was stained with 10-nonyl acridine orange (NAO) which is a mitochondrion-selective fluorescent probe known to form a stable complex with cardiolipin, a phospholipid found only in mitochondria. By micromanipulation, the injection end of the capillary was brought into contact with the tissue exhibiting fluorescently labeled mitochondria. Sampling from a region similar in size to the cross section of a single fiber was carried out by applying 11 kPa of negative pressure for 3 s. When an electric field of -200V/cm was applied, fluorescently labeled mitochondria electromigrated and were individually detected by postcolumn LIF detection. For each sample, the electropherogram displays a migration time window with a collection of narrow peaks. The collection of individual peak measurements is represented as a distribution of individual intensities related to cardiolipin content of mitochondria and a distribution of individual electrophoretic mobilities. Positioning the capillary injection end was sufficiently spatially accurate to deplete mitochondria in the sampled region upon repetitive injections. Treatment of a muscle cross section with a protease (trypsin) prior to mitochondria sampling resulted in a higher number of detected mitochondria, suggesting that one of the effects of this enzyme is a partial digestion of the muscles myofibrils, which eases the release of interfibrillar mitochondria entangled within these fibers. The protease treatment also resulted in changes to the electrophoretic mobility distribution of individual mitochondria, which may imply that partial digestion of proteins bound to the mitochondria contributes to the alteration in the electrophoretic mobility of mitochondria. The ability to sample a region as small as a single muscle fiber cross section and its direct CE-LIF analysis opens exciting possibilities for the direct analysis of muscle biopsies and mapping the mitochondrial electrophoretic properties in highly heterogeneous tissues. 相似文献
183.
We introduce instrumentation and methodology for two-channel chemical cytometry of sister cells-two cells born from division of the same mother cell. The method is based on capillary electrophoresis with laser-induced fluorescence detection and allows simultaneously probing multiple intracellular components in sister cells. To test the new technology, we compared the expression patterns of green fluorescent protein (GFP) between the sisters in cultured cancer cells stably transfected with a GFP-expressing construct. We found that all sister cells had detectable asymmetry in the GFP expression patterns with a confidence level of higher than 95%. To our best knowledge, this is the first reported observation of asymmetric patterns of protein expression in sister cells in a cancer cell line. The proposed technology can reliably detect minor differences in chemical contents between sister cells, which makes it a potentially indispensable tool in studying the molecular mechanisms of developmental processes. It will be especially valuable in quantitative studies of cells with complex proliferation kinetics (e.g., stem cells). 相似文献
184.
A hybrid multi-objective shuffled frog-leaping algorithm for a mixed-model assembly line sequencing problem 总被引:4,自引:0,他引:4
In this paper, a mixed-model assembly line (MMAL) sequencing problem is studied. This type of production system is used to manufacture multiple products along a single assembly line while maintaining the least possible inventories. With the growth in customers’ demand diversification, mixed-model assembly lines have gained increasing importance in the field of management. Among the available criteria used to judge a sequence in MMAL, the following three are taken into account: the minimization of total utility work, total production rate variation, and total setup cost. Due to the complexity of the problem, it is very difficult to obtain optimum solution for this kind of problems by means of traditional approaches. Therefore, a hybrid multi-objective algorithm based on shuffled frog-leaping algorithm (SFLA) and bacteria optimization (BO) are deployed. The performance of the proposed hybrid algorithm is then compared with three well-known genetic algorithms, i.e. PS-NC GA, NSGA-II, and SPEA-II. The computational results show that the proposed hybrid algorithm outperforms the existing genetic algorithms, significantly in large-sized problems. 相似文献
185.
186.
Hossein Ghodosi 《Information Processing Letters》2007,104(5):179-182
This paper analyses the security of Naor-Pinkas' distributed oblivious transfer [M. Naor, B. Pinkas, Distributed oblivious transfer, in: Advances in Cryptology—Proceedings of ASIACRYPT'00, Lecture Notes in Computer Science, vol. 1976, Springer-Verlag, 2000]. It is shown that the schemes presented in the paper do not protect the chooser/sender in the information theoretic sense. 相似文献
187.
Seyed Hadi Ghaderi Hassan Moslemi NaeiniGholam Hossein Liaghat 《International Journal of Impact Engineering》2007
Based on the concept of Tensor Code a numerical method is presented for analysis of the plastic deformation process of circular sheet metals subjected to transverse impact loading. In the solution process, the equation of motion is solved explicitly with finite difference method in a series of small time steps over a Lagrangian mesh of zones. Using this method, a code has been developed and utilized for investigation of the deformation behavior of an explosively loaded circular sheet metal under various conditions. Deformation characteristics of a sheet under rectangular and triangular pressure distributions are discussed. It is shown that when these simple distributions are combined with each other, their individual effects on the deformation behavior are also combined in the deformation process. Effects of shape and duration of pressure pulse as well as boundary conditions have been explored. Moreover, results of the numerical simulation have been compared with those of theoretical solution and experiments reported by other researchers. Good agreements between them show the validity of the developed code. 相似文献
188.
One of the most important needs in the post‐genome era is providing the researchers with reliable and efficient computational tools to extract and analyse this huge amount of biological data, in which DNA copy number variation (CNV) is a vitally important one. Array‐based comparative genomic hybridisation (aCGH) is a common approach in order to detect CNVs. Most of methods for this purpose were proposed for one‐dimensional profiles. However, slightly this focus has moved from one‐ to multi‐dimensional signals. In addition, since contamination of these profiles with noise is always an issue, it is highly important to have a robust method for analysing multi‐sample aCGH profiles. In this study, the authors propose robust group fused lasso which utilises the robust group total variations. Instead of l 2,1 norm, the l 1 − l 2 M‐estimator is used which is more robust in dealing with non‐Gaussian noise and high corruption. More importantly, Correntropy (Welsch M‐estimator) is also applied for fitting error. Extensive experiments indicate that the proposed method outperforms the state‐of‐the art algorithms and techniques under a wide range of scenarios with diverse noises.Inspec keywords: genomics, DNA, molecular biophysics, Gaussian noise, entropyOther keywords: robust group fused lasso, multisample copy number variation detection, post‐genome era, computational tools, biological data, DNA copy number variation, array‐based comparative genomic hybridisation, one‐dimensional profiles, one‐dimensional signals, multidimensional signals, profile contamination, multisample aCGH profiles, robust group total variations, l1 ‐l2 M‐estimator, nonGaussian noise, correntropy, Welsch M‐estimator, fitting error, diverse noises 相似文献
189.
Fereidoon Moghadas Nejad Javad Tanzadeh Gholam Hossein Hamedi 《International Journal of Pavement Engineering》2016,17(4):353-362
Rutting is considered as one of the major damages in asphalt mixtures. In this study, different types of nanoparticles such as TiO2, Al2O3, Fe2O3 and ZnO in different percentages were added to the base asphalt binder in order to decrease the rutting potential of hot-mix asphalt (HMA). In the first step, asphalt binder tests for characteristics such as penetration grade, ductility, softening point and viscosity were performed on the asphalt binder modified by the nanoparticles. Then, after preparing HMA samples, the static creep test was done at two stress levels at a specific temperature. Results of this study showed that using the nanoparticles improved the behavioural properties of the asphalt binder and decreased rutting in asphalt mix samples. Furthermore, scanning electron microscope images taken from the asphalt binder samples modified by the nanoparticles demonstrated that these nanoparticles were properly distributed in the asphalt binder space and had a positive effect on the rutting performance of the asphalt mixes. 相似文献
190.
Predicting missing links and links that may occur in the future in social networks is an attention grabbing topic amid the social network analysts. Owing to the relationship between human‐based system and social sciences in this field, granular computing can help us to model the systems more effectively. The present study aims to propose two new similarity indices, based on granular computing approach and fuzzy logic. It also presents a new hybrid model for creating synergy between various link prediction models. Results show that fuzzy system analysis, in comparison with the crisp approach, can make more effective predictions through better expression of network characteristics. The indices are tested on collaboration networks. It is found that the accuracy of predictions is significantly higher than the crisp approach. It can modify the models for computing the strength of the links and/or predicting the evolutions of the social networks. 相似文献