全文获取类型
收费全文 | 5895篇 |
免费 | 127篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 182篇 |
综合类 | 9篇 |
化学工业 | 1443篇 |
金属工艺 | 144篇 |
机械仪表 | 121篇 |
建筑科学 | 337篇 |
矿业工程 | 22篇 |
能源动力 | 138篇 |
轻工业 | 649篇 |
水利工程 | 63篇 |
石油天然气 | 8篇 |
无线电 | 401篇 |
一般工业技术 | 771篇 |
冶金工业 | 1068篇 |
原子能技术 | 80篇 |
自动化技术 | 595篇 |
出版年
2021年 | 81篇 |
2020年 | 57篇 |
2019年 | 68篇 |
2018年 | 58篇 |
2017年 | 72篇 |
2016年 | 98篇 |
2015年 | 77篇 |
2014年 | 124篇 |
2013年 | 238篇 |
2012年 | 175篇 |
2011年 | 267篇 |
2010年 | 168篇 |
2009年 | 180篇 |
2008年 | 212篇 |
2007年 | 186篇 |
2006年 | 184篇 |
2005年 | 157篇 |
2004年 | 148篇 |
2003年 | 119篇 |
2002年 | 133篇 |
2001年 | 87篇 |
2000年 | 98篇 |
1999年 | 107篇 |
1998年 | 192篇 |
1997年 | 156篇 |
1996年 | 116篇 |
1995年 | 114篇 |
1994年 | 100篇 |
1993年 | 91篇 |
1992年 | 74篇 |
1991年 | 69篇 |
1990年 | 79篇 |
1989年 | 79篇 |
1988年 | 68篇 |
1987年 | 69篇 |
1986年 | 65篇 |
1985年 | 88篇 |
1984年 | 76篇 |
1983年 | 88篇 |
1982年 | 75篇 |
1981年 | 66篇 |
1980年 | 63篇 |
1979年 | 63篇 |
1978年 | 69篇 |
1977年 | 81篇 |
1976年 | 94篇 |
1975年 | 60篇 |
1974年 | 66篇 |
1973年 | 64篇 |
1972年 | 52篇 |
排序方式: 共有6031条查询结果,搜索用时 15 毫秒
91.
Acevedo D Jackson CD Drury F Laidlaw DH 《IEEE transactions on visualization and computer graphics》2008,14(4):877-884
We describe an experiment in which art and illustration experts evaluated six 2D vector visualization methods. We found that these expert critiques mirrored previously recorded experimental results; these findings support that using artists, visual designers and illustrators to critique scientific visualizations can be faster and more productive than quantitative user studies. Our participants successfully evaluated how well the given methods would let users complete a given set of tasks. Our results show a statistically significant correlation with a previous objective study: designers' subjective predictions of user performance by these methods match users measured performance. The experts improved the evaluation by providing insights into the reasons for the effectiveness of each visualization method and suggesting specific improvements. 相似文献
92.
Keefe DF Acevedo D Miles J Drury F Swartz SM Laidlaw DH 《IEEE transactions on visualization and computer graphics》2008,14(4):835-847
We present four studies investigating tools and methodologies for artist-scientist-technologist collaboration in designing multivariate, virtual reality (VR) visualizations. Design study 1 identifies the promise of 3D drawing-style interfaces for VR design and also establishes limitations of these tools with respect to precision and support for animation. Design study 2 explores animating artist-created visualization designs with scientific 3D fluid flow data. While results captured an accurate sense of flow that was advantageous as compared to the results of study 1, the potential for visual exploration using the design tools tested was limited. Design study 3 reveals the importance of a new 3D interface that overcomes the precision limitation found in study 1 while remaining accessible to artist collaborators. Drawing upon previous results, design study 4 engages collaborative teams in a design process that begins with traditional paper sketching and moves to animated, interactive, VR prototypes "sketched" by designers in VR using interactive 3D tools. Conclusions from these four studies identify important characteristics of effective artist-accessible VR visualization design tools and lead to a proposed formalized methodology for successful collaborative design that we expect to be useful in guiding future collaborations. We call this proposed methodology Scientific Sketching. 相似文献
93.
Hadwiger M Laura F Rezk-Salama C Höllt T Geier G Pabel T 《IEEE transactions on visualization and computer graphics》2008,14(6):1507-1514
This paper presents a novel method for interactive exploration of industrial CT volumes such as cast metal parts, with the goal of interactively detecting, classifying, and quantifying features using a visualization-driven approach. The standard approach for defect detection builds on region growing, which requires manually tuning parameters such as target ranges for density and size, variance, as well as the specification of seed points. If the results are not satisfactory, region growing must be performed again with different parameters. In contrast, our method allows interactive exploration of the parameter space, completely separated from region growing in an unattended pre-processing stage. The pre-computed feature volume tracks a feature size curve for each voxel over time, which is identified with the main region growing parameter such as variance. A novel 3D transfer function domain over (density, feature size, time) allows for interactive exploration of feature classes. Features and feature size curves can also be explored individually, which helps with transfer function specification and allows coloring individual features and disabling features resulting from CT artifacts. Based on the classification obtained through exploration, the classified features can be quantified immediately. 相似文献
94.
Walter Feldheim Ernst Hartmut Reimerdes und Gernot-Rainer Storm 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1977,165(4):204-206
Zusammenfassung Zur quantitativen Bestimmung von Coffein in biologischem Material wird ein kombiniertes Verfahren aus Dünnschichtchromatographie und Densitometrie beschrieben. Das Verfahren läßt Bestimmungen im Nanogramm-Bereich zu. Das Probenvolumen liegt unter 100 l.Die Proben — Capillarblut — werden zunächst mit dem gleichen Volumen Chloroform extrahiert. Anschließend wird das Coffein mittels Dünnschichtchromatographie von Begleitstoffen und störenden Substanzen abgetrennt. Es werden Kieselgel-60-Fertigplatten und Chlorofom/Aceton (9 + 1; v/v) als Fließmittel verwendet, dabei beträgt die Laufzeit 30 min.Die quantitative densitometrische Auswertung erfolgt durch Remissionsmessung bei 273 nm. Im Bereich von 10–60 ng Coffein/Fleck verläuft die Eichkurve linear. 1 mg/I Coffein kann noch sicher quantitativ erfaßt werden. Die Nachweisgrenze liegt bei 0,1 mg/1.
A quantitative micromethod for the caffeine determination
Summary A combined procedure with thin-layer-chromatography and densitometry is described for the quantitative estimation of caffeine in biological material. This method ist applicable in the nanogram range. Test samples of less than 100 l may be used. The samples (capillary-blood) are extracted with the same volume of chloroform. Caffeine is separated from interfering compounds by thin-layer-chromatography. Commercial silica-60-plates with chloroform/acetone (9 + 1; v/v) as solvent are used. The running time is about 30 min. The quantitative densitometric determinations are performed in the remission mode at 273 nm. In the range from 10 to 60 ng/spot the calibration curve is linear. Accurate quantitative data will be obtained even at concentrations of 1 mg/1 caffeine. The detection limit is at about 0.1 mg/1.相似文献
95.
LeCronier DJ Papakonstantinou JS Gheevarughese V Beran CD Walter NE Atkinson PJ 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2012,226(4):330-336
Previous animal models have been developed to study intramedullary nailing for challenging segmental defects in the tibia. In large animals, interlocked nail fixation created a stable environment suitable to study new bone growth technologies placed in the defect. To our knowledge, there are no comparable interlocked tibial defect models for the rabbit in which new technologies could be evaluated. Such a model would be helpful since the rabbit is a popular initial model for orthopedic research studies owing to its wide availability and low cost. While numerous studies have nailed the rabbit tibia, all were non-locked implants that allowed some degree of instability between the fracture fragments. In addition, the non-locked nails were constructed of stainless steel, whereas human nails are increasingly made from titanium alloy. In the current study, an interlocked titanium nail was developed for the rabbit tibia. It was implanted in cadaver tibiae and subjected to fatigue cycling in combined compression and bending at physiologic levels to 21,061 cycles. This duration is estimated to represent 12 weeks of gait by the animal. Before and after fatigue cycling, monotonic testing was performed in compression and bending at physiologic levels. The intact contralateral limbs served as controls. All limbs completed the cycling; the instrumented limbs exhibited interfragmentary cyclic strain amplitudes during fatigue (616 +/- 139 micro-strain), which was significantly greater than the control limbs (136 +/- 35 microstrain). Monotonic strain amplitudes for the test limbs in bending and compression were 4839 +/- 1028 and 542 +/- 122 microstrain, respectively; corresponding values for the control bones were 407 +/- 118 and 95 +/- 38 microstrain, respectively. These data are similar to those presented in prior studies in larger bone models. The current study presents one method for interlocked nail fixation for this complex tibial shaft fracture in a small animal. 相似文献
96.
97.
This paper presents the design and implementation of an integrated application program called ArcFVS that links the Forest Vegetation Simulator (FVS) and a Geographic Information System (GIS) to realize spatial selection of input files and graphic display of modeling output. Data for testing and running the model came from the U.S. Forest Service’s Forest Inventory and Analysis (FIA) Database and were also collected in field surveys in north-central Indiana. ArcFVS 1.0 is designed using the ArcGIS software from the Environmental Systems Research Institute (ESRI) and the Visual Basic for Applications (VBA) programming environment to manipulate ESRI’s ArcObjects. The resulting product offers custom functions as commands in a new menu or as tools on a new toolbar. They are used to: select spatially or by attribute the forest plots to be projected by FVS, create the FVS input files for the selected plots and display in a geospatial environment different types of FVS output (text output files, tables with variables of interest and visualization image files). Advantages of ArcFVS 1.0 include the new GIS capabilities, enhanced format translation functions and the standardized programming environment. 相似文献
98.
Jongchul Song Walter R. Fagerlund Carl T. Haas Clyde B. Tatum Jorge A. Vanegas 《Canadian Metallurgical Quarterly》2005,131(6):723-733
Prefabrication, preassembly, modularization, and off-site fabrication, collectively termed as prework have become more viable with recent advances in design and information technologies. These construction methods offer a substantial opportunity to improve project performance when circumstances merit. Successful implementation of these methods on a particular project requires systematic analysis and early decision making based on specific factors of the project. This paper identifies those factors influencing decisions on the use of prework, and current industry practices for evaluating the applicability of prework on industrial projects. It then presents a decision framework to assist industry practitioners with evaluating the applicability of prework on their project, and describes a computerized tool to aid project teams in the decision-making process. The developed framework and tool are useful and effective in the decision-making process, and easy to use, as validated by practitioners in the industry. 相似文献
99.
Ferrer Emilio; Salthouse Timothy A.; McArdle John J.; Stewart Walter F.; Schwartz Brian S. 《Canadian Metallurgical Quarterly》2005,20(3):412
Longitudinal multivariate mixed models were used to examine the correlates of change between memory and processing speed and the contribution of age and retest to such change correlates. Various age- and occasion-mixed models were fitted to 2 longitudinal data sets of adult individuals (N > 1,200). For both data sets, the results indicated that the correlation between the age slopes of memory and processing speed decreased when retest effects were included in the model. If retest effects existed in the data but were not modeled, the correlation between the age slopes was positively biased. The authors suggest that although the changes in memory and processing speed may be correlated over time, age alone does not capture such a covariation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
100.
Finding changed identifiers is important for understanding the difference between two versions of a program and for detecting and resolving conflicts while merging variants of a program together. Standard practice for differencing and merging relies on line based techniques that do not recognize renamed identifiers. The design and implementation of a tool to automatically detect renamed identifiers between two versions of a program is presented. The system uses an abstract representation of language constructs to enable language awareness without introducing language dependence. Modules for Java and Scheme have been written. The detector works with multiple file pairs, taking into account renamings that span several files. A case study is presented that demonstrates proof of concept. The detector is part of a suite of intelligent differencing and merging programs that exploit the static semantics of programming languages. 相似文献