全文获取类型
收费全文 | 1027篇 |
免费 | 31篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 123篇 |
金属工艺 | 34篇 |
机械仪表 | 43篇 |
建筑科学 | 11篇 |
矿业工程 | 17篇 |
能源动力 | 31篇 |
轻工业 | 57篇 |
水利工程 | 11篇 |
石油天然气 | 2篇 |
无线电 | 58篇 |
一般工业技术 | 178篇 |
冶金工业 | 368篇 |
原子能技术 | 2篇 |
自动化技术 | 116篇 |
出版年
2021年 | 16篇 |
2020年 | 15篇 |
2019年 | 13篇 |
2018年 | 16篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 12篇 |
2014年 | 9篇 |
2013年 | 45篇 |
2012年 | 20篇 |
2011年 | 34篇 |
2010年 | 19篇 |
2009年 | 18篇 |
2008年 | 31篇 |
2007年 | 38篇 |
2006年 | 32篇 |
2005年 | 22篇 |
2004年 | 19篇 |
2003年 | 24篇 |
2002年 | 13篇 |
2001年 | 20篇 |
2000年 | 21篇 |
1999年 | 26篇 |
1998年 | 78篇 |
1997年 | 58篇 |
1996年 | 43篇 |
1995年 | 28篇 |
1994年 | 20篇 |
1993年 | 46篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 18篇 |
1976年 | 26篇 |
1974年 | 6篇 |
1973年 | 10篇 |
1971年 | 6篇 |
1970年 | 7篇 |
1969年 | 8篇 |
排序方式: 共有1059条查询结果,搜索用时 15 毫秒
31.
32.
Models of human reaction to vehicle environments 总被引:2,自引:0,他引:2
Models for predicting human comfort responses to environmental variables are presented for diverse vehicles. Air mode studies reveal that comfort is a function of vertical and transverse accelerations, noise levels and seat factors, as well as manoeuvre conditions. Comfort models for ground-based vehicles involve roll rates and noise levels. 相似文献
33.
M. C. Freeman G. R. Buell L. E. Hay W. B. Hughes R. B. Jacobson J. W. Jones S. A. Jones J. H. Lafontaine K. R. Odom J. T. Peterson J. W. Riley J. S. Schindler C. Shea J. D. Weaver 《河流研究与利用》2013,29(7):906-918
Efforts to conserve stream and river biota could benefit from tools that allow managers to evaluate landscape‐scale changes in species distributions in response to water management decisions. We present a framework and methods for integrating hydrology, geographic context and metapopulation processes to simulate effects of changes in streamflow on fish occupancy dynamics across a landscape of interconnected stream segments. We illustrate this approach using a 482 km2 catchment in the southeastern US supporting 50 or more stream fish species. A spatially distributed, deterministic and physically based hydrologic model is used to simulate daily streamflow for sub‐basins composing the catchment. We use geographic data to characterize stream segments with respect to channel size, confinement, position and connectedness within the stream network. Simulated streamflow dynamics are then applied to model fish metapopulation dynamics in stream segments, using hypothesized effects of streamflow magnitude and variability on population processes, conditioned by channel characteristics. The resulting time series simulate spatially explicit, annual changes in species occurrences or assemblage metrics (e.g. species richness) across the catchment as outcomes of management scenarios. Sensitivity analyses using alternative, plausible links between streamflow components and metapopulation processes, or allowing for alternative modes of fish dispersal, demonstrate large effects of ecological uncertainty on model outcomes and highlight needed research and monitoring. Nonetheless, with uncertainties explicitly acknowledged, dynamic, landscape‐scale simulations may prove useful for quantitatively comparing river management alternatives with respect to species conservation. Published 2012. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
34.
Functions that optimize Laplacian‐based energies have become popular in geometry processing, e.g. for shape deformation, smoothing, multiscale kernel construction and interpolation. Minimizers of Dirichlet energies, or solutions of Laplace equations, are harmonic functions that enjoy the maximum principle, ensuring no spurious local extrema in the interior of the solved domain occur. However, these functions are only C0 at the constrained points, which often causes smoothness problems. For this reason, many applications optimize higher‐order Laplacian energies such as biharmonic or triharmonic. Their minimizers exhibit increasing orders of continuity but lose the maximum principle and show oscillations. In this work, we identify characteristic artifacts caused by spurious local extrema, and provide a framework for minimizing quadratic energies on manifolds while constraining the solution to obey the maximum principle in the solved region. Our framework allows the user to specify locations and values of desired local maxima and minima, while preventing any other local extrema. We demonstrate our method on the smoothness energies corresponding to popular polyharmonic functions and show its usefulness for fast handle‐based shape deformation, controllable color diffusion, and topologically‐constrained data smoothing. 相似文献
35.
Wetter Spencer; Peavy Guerry; Jacobson Mark; Hamilton Joanne; Salmon David; Murphy Claire 《Canadian Metallurgical Quarterly》2005,19(4):428
The influence of Huntington's disease (HD) on the olfactory event-related potential (OERP), an electrophysiological measure of olfactory information processing, has not been reported to date. In the present study, olfactory and auditory event-related potentials (ERPs) were recorded monopolarly from Fz, Cz, and Pz electrode sites in 8 patients with HD and 8 age- and gender-matched control participants. Results demonstrated that individuals with HD were delayed compared with controls on the P3 component of the OERP (p 相似文献
36.
This paper considers a linear system under nested saturation. Nested saturation arises, for example, when the actuator is subject to magnitude and rate saturation simultaneously. A condition is derived in terms of a set of auxiliary feedback gains for determining if a given ellipsoid is contractively invariant. Moreover, this condition is shown to be equivalent to linear matrix inequalities (LMIs) in the actual and auxiliary feedback gains. As a result, the estimation of the domain of attraction for a given set of feedback gains can be formulated as an optimization problem with LMI constraints. By viewing the feedback gains as extra free parameters, the optimization problem can be used for controller design. 相似文献
37.
J. G. Mantovani D. P. Allison R. J. Warmack T. L. Ferrell J. R. Ford R. E. Manos J. R. Thompson B. B. Reddick K. Bruce Jacobson 《Journal of microscopy》1990,158(1):109-116
We present scanning tunnelling microscope (STM) images of untreated tobacco mosaic virus (TMV) deposited on thermally evaporated and on sputter-coated palladium/gold 40:60 (Pd/Au) substrates, and imaged under ordinary atmospheric conditions. The TMV imaged on both evaporated and sputter-coated substrates was consistently several times wider than the known diameter of the virus. TMV on evaporated Pd/Au became overcoated with Pd/Au material during sample preparation and appeared elevated in STM images, whereas TMV on sputter-coated Pd/Au appeared as depressions. When naked TMV were intentionally overcoated with Pd/Au, the STM images were found to be similar to those for TMV on evaporated Pd/Au. 相似文献
38.
B.Jacobson 《传动技术(上海)》2003,17(1):34-45
动力换档即自动变速器传统的换档是采用脱开A档离合器和接合B档离合器来使A档换到B档,本文试用一个第三离合器的设想,实质上,这种第三离合器可以作为传统的离合器之一,只用于其他档位换档,这就意味着可以在原来的变速器内采用一个最新的控制软件,试验在传统的控制原理协调平顺性和磨损之间关系已不存在困难,该磨损或不平顺性大约可降低为按照传统挂高档的一半,本文发现在采用一个附加离合器的最大趋向是它属于比挂高档高的高档,这里采用一个普通和简单的模型来进行理想研究,而仿真实例则采用一个齿轮箱的一个更加详细的模型。 相似文献
39.
Martti Heinonen Miltiadis Anagnostou Stephanie Bell Mark Stevens Robert Benyon Reidun Anita Bergerud Jovan Bojkovski Rien Bosma Jan Nielsen Norbert B?se Plunkett Cromwell Aliye Kartal Dogan Seda Aytekin Ali Uytun Vito Fernicola Krzysztof Flakiewicz Bertrand Blanquart Domen Hudoklin Per Jacobson Anders Kentved Isabel Lóio George Mamontov Alexandra Masarykova Helmut Mitter Regina Mnguni Jan Otych Anton Steiner Nagyné Szilágyi Zsófia Davor Zvizdic 《International Journal of Thermophysics》2012,33(8-9):1422-1437
In the field of humidity quantities, the first CIPM key comparison, CCT-K6 is at its end. The corresponding European regional key comparison, EUROMET.T-K6, was completed in early 2008, about 4?years after the starting initial measurements in the project. In total, 24 NMIs from different countries took part in the comparison. This number includes 22 EURAMET countries, and Russia and South Africa. The comparison covered the dew-point temperature range from ?50?°C to +20?°C. It was carried out in three parallel loops, each with two chilled mirror hygrometers as transfer standards in each loop. The comparison scheme was designed to ensure high quality results with evenly spread workload for the participants. It is shown that the standard uncertainty due to the long-term instability was smaller than 0.008?°C in all loops. The standard uncertainties due to links between the loops were found to be smaller than 0.025?°C at ?50?°C and 0.010?°C elsewhere. Conclusions on the equivalence of the dew-point temperature standards are drawn on the basis of calculated bilateral degrees of equivalence and deviations from the EURAMET comparison reference values (ERV). Taking into account 16 different primary dew-point realizations and 8 secondary realizations, the results demonstrate the equivalence of a large number of laboratories at an uncertainty level that is better than achieved in other multilateral comparisons so far in the humidity field. 相似文献
40.
Ivar Jacobson Shihong Huang Mira Kajko-Mattsson Paul McMahon Ed Seymour 《Programming and Computer Software》2012,38(1):1-12
The purpose of writing this Three Year Vision paper is threefold. Firstly, it briefly recaps the progress Semat has made thus
far; secondly, it lays out the future directions for people working actively within the Semat community; thirdly, it provides
the background for seeking funding support from agencies, such as the European Community and the like. Funding support is
necessary to sustain the ongoing activities of Semat and its growth into a broader community effort, as most people working
within Semat are volunteers. As such, the paper may be both too much and too little for the wider supporter base. However,
we intend to make our work fully transparent, hence, we publish it widely. We seek feedback and comments from supporters and
signatories in order to improve the vision. In this context, other companion papers are being written to better address the
specific needs for the practitioners, the industry and the academia. 相似文献