全文获取类型
收费全文 | 31990篇 |
免费 | 3383篇 |
国内免费 | 1931篇 |
专业分类
电工技术 | 2103篇 |
综合类 | 2335篇 |
化学工业 | 4573篇 |
金属工艺 | 1601篇 |
机械仪表 | 3861篇 |
建筑科学 | 1351篇 |
矿业工程 | 731篇 |
能源动力 | 1485篇 |
轻工业 | 789篇 |
水利工程 | 559篇 |
石油天然气 | 1527篇 |
武器工业 | 363篇 |
无线电 | 2489篇 |
一般工业技术 | 2759篇 |
冶金工业 | 898篇 |
原子能技术 | 139篇 |
自动化技术 | 9741篇 |
出版年
2024年 | 115篇 |
2023年 | 476篇 |
2022年 | 751篇 |
2021年 | 1018篇 |
2020年 | 1022篇 |
2019年 | 910篇 |
2018年 | 902篇 |
2017年 | 1106篇 |
2016年 | 1292篇 |
2015年 | 1427篇 |
2014年 | 2021篇 |
2013年 | 2051篇 |
2012年 | 2043篇 |
2011年 | 2674篇 |
2010年 | 1832篇 |
2009年 | 2072篇 |
2008年 | 2031篇 |
2007年 | 2343篇 |
2006年 | 1942篇 |
2005年 | 1728篇 |
2004年 | 1449篇 |
2003年 | 1271篇 |
2002年 | 1002篇 |
2001年 | 786篇 |
2000年 | 676篇 |
1999年 | 476篇 |
1998年 | 390篇 |
1997年 | 287篇 |
1996年 | 214篇 |
1995年 | 201篇 |
1994年 | 165篇 |
1993年 | 141篇 |
1992年 | 116篇 |
1991年 | 87篇 |
1990年 | 69篇 |
1989年 | 60篇 |
1988年 | 31篇 |
1987年 | 24篇 |
1986年 | 25篇 |
1985年 | 16篇 |
1984年 | 18篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Joern Ploennigs Mario Neugebauer Klaus Kabitzsch 《International Journal on Software Tools for Technology Transfer (STTT)》2006,8(6):607-620
Large technical systems need to be designed both reliable and efficient. Specialized design tools offer therefore a simplified,
abstract design and extend details autonomously in the background. Analytic and simulation based models could improve the
quality by testing and dimensioning the design before implementation, but setting up the necessary models is time-consuming
and expensive. Therefore many developers ask for analysis tools which are able to create their models from the available information
in the design tools. This paper presents such an automated modeling approach basing on an existing design database at the
example of a network analysis for building automation fieldbuses. The process of automated modeling is unfolded, and the potentials
and limitations are discussed. 相似文献
62.
Modeling mercury speciation is an important requirement for estimating harmful emissions from coal-fired power plants and developing strategies to reduce them. First-principle models based on chemical, kinetic, and thermodynamic aspects exist, but these are complex and difficult to develop. The use of modern data-based machine learning techniques has been recently introduced, including neural networks. Here we propose an alternative approach using abductive networks based on the group method of data handling (GMDH) algorithm, with the advantages of simplified and more automated model synthesis, automatic selection of significant inputs, and more transparent input–output model relationships. Models were developed for predicting three types of mercury speciation (elemental, oxidized, and particulate) using a small dataset containing six inputs parameters on the composition of the coal used and boiler operating conditions. Prediction performance compares favourably with neural network models developed using the same dataset, with correlation coefficients as high as 0.97 for training data. Network committees (ensembles) are proposed as a means of improving prediction accuracy, and suggestions are made for future work to further improve performance. 相似文献
63.
杨志宏 《哈尔滨工业大学学报》2007,39(9):1507-1512
从高校组织元素的构成与描述方法研究入手,分别建立了高校组织机构视图和高校办学活动过程模型.通过人流、物流、资金流、信息流在组织机构视图与办学活动过程模型之间的交换,建立了各组织元素之间的链接关系,从而构建出了整体性、系统性的高校组织模型.引入学科专业作为建模构件,通过基于进程的办学活动过程分析,反映了高校组织的特点,基本满足了高校组织建模的复杂性、特异性要求. 相似文献
64.
This paper presents a new approach for using stereo and motion correspondences to solve the problem of tracking multiple independently moving features. In this approach, quantitative relational structure (QRS) is proposed as a framework for the integration of stereo–motion correspondences. The similarity function, tightly coupled to stereo and motion cues, is constructed on QRS, and then energy function E2 consisting of the similarity function is defined. The tracking problem can be converted into the maximization problem of the energy function E2. The stereo and motion correspondences that maximize E2 are recovered by applying an extended graduated assignment algorithm. The relaxation labeling method is also presented for the comparison with the proposed method. Experimental results are presented to illustrate the performance of the proposed method. 相似文献
65.
66.
《Drying Technology》2007,25(1):75-84
This article proposes a multiscale computational model able to calculate energy consumption in a batch lumber kiln. A dual-scale computational model of wood drying deals with the boards/stack interaction and serves as a basis for the present work. A new module was added here that calculates heat losses through kiln walls (convection, condensation) and the energy used by each kiln component (fans, heating elements, humidifier, vacuum pump, etc.). The corresponding mathematical formulation is presented and then theoretical results are compared to those collected in an industrial vacuum kiln. As application example, the effect of air reversal, air velocity, and kiln insulation are exhibited, which depicts the great potential and prospects of this new tool for energy savings in relation to the product quality. 相似文献
67.
68.
数值地形图的生成及其水文地貌特征评价 总被引:17,自引:2,他引:15
数值地形图(DEM)是利用地理信息系统(GIS)进行流域水文模拟的基础, 其精度直接影响模拟结果在没有现成的数值地形图时, 应用人员往往利用传统的地形图来生成它. 本文分别采用Arc/Info地理信息系统软件提供的哈奇逊法和不规则三角网五次插值法, 对一个实验流域的高程取样点进行插值, 生成了4种不同的数值地形图, 从凹洼分布、流域界定、河网提取、地面坡度和地形指数、以及地面径流汇成等方面, 对它们的水文地貌精度进行了比较. 结果表明, 两种方法都能生成由高程点群所反映的地形, 然而由于哈奇逊法能够结合流域的河网结构及其具有物理基础的水文地貌加强法来处理凹洼问题, 因此大大地提高了其所生成的流域数值地形图水文地貌特征精度. 相似文献
69.
We modeled nisin's anticlostridial activity and assessed the antagonistic or potentiating influences of food ingredients. The model systems contained yeast extract, proteose peptone, and glucose; were supplemented with protein (0.075, 0.75, 7.5% w/v), phospholipid (0.075, 0.75, 7.5% w/v), or soluble starch (5, 17.5, 30% w/v); and were adjusted to pH 5.5, 6.0, or 6.5. Samples inoculated with 104/mL spores were incubated at 15, 25, or 35°C. Statistical analysis developed an equation (r2= 0.76) that modeled the response and identified temperature as the most significant (α 0.001) variable. Nisin lost effectiveness with increasing temperature. Nisin concentration had significant positive and phospholipid negative, linear effects. Many interactive effects were significant (α 0.20). Nisin inhibited C. botulinum until its residual level dropped below a threshold, which decreased from 154 IU/mL at 35°C to 12 IU/mL at 15°C. 相似文献
70.
Mathematical models describing dynamics of crust formation and kinetics of crust color and firmness changes were developed for the deep-fat frying of beef meatballs. Good agreement (R2 ranged between 0.815 and 0.987) was observed between experimental and predicted data. Crust color lightness, redness, and yellowness decreased exponentially with frying time while total color change increased. All color parameters followed first order reaction kinetics. Meatball firmness was measured by peak force obtained from a puncture test whose kinetics model had a reaction rate constant of 5.39E-3 1/(s.Nn-1) and a reaction order of 0.0013. 相似文献