全文获取类型
收费全文 | 10482篇 |
免费 | 836篇 |
国内免费 | 338篇 |
专业分类
电工技术 | 435篇 |
综合类 | 637篇 |
化学工业 | 2340篇 |
金属工艺 | 299篇 |
机械仪表 | 580篇 |
建筑科学 | 836篇 |
矿业工程 | 495篇 |
能源动力 | 350篇 |
轻工业 | 2797篇 |
水利工程 | 332篇 |
石油天然气 | 409篇 |
武器工业 | 23篇 |
无线电 | 373篇 |
一般工业技术 | 655篇 |
冶金工业 | 682篇 |
原子能技术 | 70篇 |
自动化技术 | 343篇 |
出版年
2024年 | 49篇 |
2023年 | 169篇 |
2022年 | 402篇 |
2021年 | 513篇 |
2020年 | 424篇 |
2019年 | 357篇 |
2018年 | 317篇 |
2017年 | 351篇 |
2016年 | 410篇 |
2015年 | 395篇 |
2014年 | 617篇 |
2013年 | 685篇 |
2012年 | 778篇 |
2011年 | 748篇 |
2010年 | 557篇 |
2009年 | 538篇 |
2008年 | 455篇 |
2007年 | 646篇 |
2006年 | 568篇 |
2005年 | 496篇 |
2004年 | 404篇 |
2003年 | 343篇 |
2002年 | 289篇 |
2001年 | 214篇 |
2000年 | 197篇 |
1999年 | 156篇 |
1998年 | 84篇 |
1997年 | 86篇 |
1996年 | 64篇 |
1995年 | 68篇 |
1994年 | 48篇 |
1993年 | 44篇 |
1992年 | 32篇 |
1991年 | 29篇 |
1990年 | 15篇 |
1989年 | 27篇 |
1988年 | 19篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 3篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1959年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
Microfluidics: Inertial Microfluidic Cell Stretcher (iMCS): Fully Automated,High‐Throughput,and Near Real‐Time Cell Mechanotyping (Small 28/2017) 下载免费PDF全文
73.
Kendra L. Van Buren François M. Hemez 《International journal for numerical methods in engineering》2016,105(5):351-371
This work proposes a method for statistical effect screening to identify design parameters of a numerical simulation that are influential to performance while simultaneously being robust to epistemic uncertainty introduced by calibration variables. Design parameters are controlled by the analyst, but the optimal design is often uncertain, while calibration variables are introduced by modeling choices. We argue that uncertainty introduced by design parameters and calibration variables should be treated differently, despite potential interactions between the two sets. Herein, a robustness criterion is embedded in our effect screening to guarantee the influence of design parameters, irrespective of values used for calibration variables. The Morris screening method is utilized to explore the design space, while robustness to uncertainty is quantified in the context of info‐gap decision theory. The proposed method is applied to the National Aeronautics and Space Administration Multidisciplinary Uncertainty Quantification Challenge Problem, which is a black‐box code for aeronautic flight guidance that requires 35 input parameters. The application demonstrates that a large number of variables can be handled without formulating simplifying assumptions about the potential coupling between calibration variables and design parameters. Because of the computational efficiency of the Morris screening method, we conclude that the analysis can be applied to even larger‐dimensional problems. (Approved for unlimited, public release on October 9, 2013, LA‐UR‐13‐27839, Unclassified.) Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
74.
Minimum Setup Minimum Aberration Two‐level Split‐plot Type Designs for Physical Prototype Testing 下载免费PDF全文
Linda Lee Ho Carla A. Vivacqua André Luís Santos de Pinho 《Quality and Reliability Engineering International》2016,32(3):1007-1020
Although new technologies allow for less effort in prototyping, physical testing still remains an important step in the product development cycle. Well‐planned experiments are useful to guide the decision‐making process. During the design of an experiment, one of the challenges is to balance limited resources and system constraints to obtain useful information. It is common that prototypes are composed of several parts, with some parts more difficult to assemble than others. And, usually, there is only one piece available of each part type and a large number of different setups. Under these conditions, designs with randomization restrictions become attractive approaches. Considering this scenario, a new and additional criterion, minimum setup, to construct split‐plot type designs is presented. Designs with the minimum number of setups of the more difficult parts, which are especially useful for screening purposes in physical prototype testing, are discussed. The use of the proposed criterion combined with minimum aberration for selecting a regular design is shown through a real application in testing car prototypes. As a tool to practitioners, catalogs of selected 32‐run minimum setup minimum aberration split‐split‐plot and split‐split‐split‐plot designs are presented. More complete catalogs are available as Supporting information. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
75.
76.
水浇地与旱地分类的研究进展 总被引:3,自引:0,他引:3
水浇地和旱地的分类研究对于粮食安全、估算农业灌溉需水量以及完善耕地二级类型的分类有着重要的作用。本文从水浇地和旱地分类的意义、分类方法以及分类应用的现状三方面,对国内外水浇地和旱地的分类研究进展及其特点进行了归纳总结,得出了三点结论:(1)参与水浇地和旱地分类的数据源主要为中低分辨率的时间序列植被指数产品以及一些辅助信息;(2)水浇地和旱地的分类特征主要为时间序列的植被指数以及一些辅助特征;(3)水浇地和旱地的分类方法主要为数字化、非监督分类和监督分类。同时指出,丰富水浇地和旱地的分类特征、引入智能型分类方法以及探索生态环境背景在水浇地和旱地分类中的应用将成为未来水浇地和旱地分类研究的重要内容。 相似文献
77.
Donggang Yu Author Vitae Tuan D. Pham Author Vitae Author Vitae Stephen T.C. Wong Author Vitae 《Pattern recognition》2009,42(4):498-508
Automated analysis of molecular images has increasingly become an important research in computational life science. In this paper some new and efficient algorithms for recognizing and analyzing cell phases of high-content screening are presented. The conceptual frameworks are based on the morphological features of cell nuclei. The useful preprocessing includes: smooth following and linearization; extraction of morphological structural points; shape recognition based morphological structure; issue of touching cells for cell separation and reconstruction. Furthermore, the novel detecting and analyzing strategies of feed-forward and feed-back of cell phases are proposed based on gray feature, cell shape, geometrical features and difference information of corresponding neighbor frames. Experiment results tested the efficiency of the new method. 相似文献
78.
Huth J Buchholz M Kraus JM Mølhave K Gradinaru C v Wichert G Gress TM Neumann H Kestler HA 《Computer methods and programs in biomedicine》2011,104(2):227-234
The direct observation of cells over time using time-lapse microscopy can provide deep insights into many important biological processes. Reliable analyses of motility, proliferation, invasive potential or mortality of cells are essential to many studies involving live cell imaging and can aid in biomarker discovery and diagnostic decisions. Given the vast amount of image- and time-series data produced by modern microscopes, automated analysis is a key feature to capitalize the potential of time-lapse imaging devices. To provide fast and reproducible analyses of multiple aspects of cell behaviour, we developed TimeLapseAnalyzer. Apart from general purpose image enhancements and segmentation procedures, this extensible, self-contained, modular cross-platform package provides dedicated modalities for fast and reliable analysis of multi-target cell tracking, scratch wound healing analysis, cell counting and tube formation analysis in high throughput screening of live-cell experiments. TimeLapseAnalyzer is freely available (MATLAB, Open Source) at http://www.informatik.uni-ulm.de/ni/mitarbeiter/HKestler/tla. 相似文献
79.
80.
A rapid screening system for heterogeneous catalyst discovery has been developed by coupling an in-house designed and fabricated high temperature vapor phase pulse reactor on-line to a GC-MS. The incorporation of gas chromatography for separation of the products with the mass spectrometry system allowed simultaneous identification and determination of reaction products and substrate conversion. This system was employed to study the vapor phase catalytic hydride transfer reduction (CHTR) of nitrobenzene with methanol as hydrogen donor on an MgO catalyst as a model reaction. Structural information of all the by-products that were formed was useful to understand the reaction mechanism. The products obtained with the new screening technique were in good agreement with conventional bench scale experiments. The rapid online screening provided an efficient methodology for optimization of reaction conditions such as catalyst loading, reaction temperature, and mole ratios. Response Surface Methodology (RSM) was used to optimize the conversion of reactants and selectivity of products. 相似文献