全文获取类型
收费全文 | 1336篇 |
免费 | 34篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 232篇 |
金属工艺 | 13篇 |
机械仪表 | 20篇 |
建筑科学 | 52篇 |
矿业工程 | 5篇 |
能源动力 | 35篇 |
轻工业 | 119篇 |
水利工程 | 12篇 |
石油天然气 | 3篇 |
无线电 | 126篇 |
一般工业技术 | 203篇 |
冶金工业 | 311篇 |
原子能技术 | 11篇 |
自动化技术 | 212篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 11篇 |
2019年 | 16篇 |
2018年 | 19篇 |
2017年 | 13篇 |
2016年 | 27篇 |
2015年 | 24篇 |
2014年 | 44篇 |
2013年 | 45篇 |
2012年 | 42篇 |
2011年 | 60篇 |
2010年 | 62篇 |
2009年 | 39篇 |
2008年 | 58篇 |
2007年 | 55篇 |
2006年 | 36篇 |
2005年 | 41篇 |
2004年 | 25篇 |
2003年 | 34篇 |
2002年 | 29篇 |
2001年 | 30篇 |
2000年 | 23篇 |
1999年 | 22篇 |
1998年 | 97篇 |
1997年 | 77篇 |
1996年 | 47篇 |
1995年 | 19篇 |
1994年 | 26篇 |
1993年 | 22篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 11篇 |
1986年 | 17篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 26篇 |
1976年 | 23篇 |
1975年 | 9篇 |
1970年 | 8篇 |
1967年 | 6篇 |
排序方式: 共有1371条查询结果,搜索用时 15 毫秒
21.
In addition to the C21 steroid 15α-hydroxypregna-4,6-dien-3,20-dione, four 1- or 2-acylated polyunsaturated monoglycerides, 1- or 2-(cis-5,8,11,14-eicosatetraenoyl)-glycerol and 1- or 2-(cis-5,8,11,14,17-eicosapentaenoyl)glycerol were identified as constituents of the prothoracic defensive gland secretion of the
dytiscid beetle Agabus affinis by gas chromatography-mass spectrometry of trimethylsilylated gland extracts. In a feeding assay with minnows, synthetic
samples of the two 2-acylated monoglycerides showed only a weak activity as a feeding deterrent. For that reason, other possible
functions of the monoglycerides are discussed, such as roles as emulsifiers of cannabimimetics. 相似文献
22.
Sascha Stanic Thomas Koch Klaus Schmid Simone Knaus Vasiliki-Maria Archodoulaki 《应用聚合物科学杂志》2021,138(28):50659
The influence of two peroxides (peroxydicarbonate/dilauroyl peroxide) with various concentrations (10–200 mmol/kg PP) and their effective opportunity to introduce long chain branched (LCB) were investigated. The dependence of a single and double extrusion step and the changes of the properties were studied. Experiments were carried out in a single screw extruder at 180°C for the first extrusion step (modification) and at 240°C for the second extrusion step (processing simulation). Melt flow rate and dynamic rheological properties were studied at a measuring temperature of 230°C. For the definitive determination of long chain branched polypropylene (LCB-PP) served the extensional rheology measurements. The mechanical properties were examined via tensile test and impact tensile test. Summarized, LCB (melt strength) could be observed via extensional rheology for all modified specimens and the mechanical properties were maintained or even improved for the modified samples. Particularly, samples containing dilauroyl peroxide display excellent mechanical properties in this study. 相似文献
23.
24.
25.
For “on board” diagnosis purposes of the injected fuel quantity flow sensitive elements based on the thermo-resistive measurement
principle were integrated into finished Common Rail injection nozzles of valve-covered orifice (VCO) or mini-sac hole (MSH)
class. Electron-discharge machining as well as electron beam welding technique are key technologies for a reliable integration
procedure. To demonstrate negligible influence on the hydraulic performance of the nozzle after modification an optical measurement
set-up is used to record temporally resolved the propagation of the spray patterns ejected from the six injection holes simultaneously.
From these investigations the impact on the structural distortion of the valve caused by the welding seam is proved as its
position can be directly linked to any chances in spray performance of each individual injection hole. Reducing the energy
input during the electron beam welding lowers substantially the asymmetry in spray patterns from hole to hole as the needle
uncovers the six injection holes more symmetrically. Besides this important finding, the numerical calculations indicate that
the implementation of the sensor chip slightly amplifies the asymmetry induced by the welding process due to an additional
weakening of the nozzle body which is confirmed experimentally. Despite these challenges, however, it is demonstrated that
appropriate parameters for the integration procedure can be found affecting the hydraulic performance negligible compared
to the original state. 相似文献
26.
A nematic polymer liquid crystal is used to construct wave plates for use at 1054 nm. Three methods of wave-plate construction are discussed: double substrate with fiber spacers in homogeneous distribution, double substrate with fiber spacers in annular distribution, and single substrate. The polymer liquid crystal shows high laser-damage resistance, making it particularly useful for high-peak-power laser applications. Alignment techniques and measurement of birefringence for the highly viscous polymer are described. 相似文献
27.
From Images to Shape Models for Object Detection 总被引:2,自引:0,他引:2
Vittorio Ferrari Frederic Jurie Cordelia Schmid 《International Journal of Computer Vision》2010,87(3):284-303
We present an object class detection approach which fully integrates the complementary strengths offered by shape matchers.
Like an object detector, it can learn class models directly from images, and can localize novel instances in the presence
of intra-class variations, clutter, and scale changes. Like a shape matcher, it finds the boundaries of objects, rather than
just their bounding-boxes. This is achieved by a novel technique for learning a shape model of an object class given images of example instances. Furthermore, we also integrate Hough-style voting with a non-rigid point matching algorithm to localize
the model in cluttered images. As demonstrated by an extensive evaluation, our method can localize object boundaries accurately
and does not need segmented examples for training (only bounding-boxes). 相似文献
28.
Objective: Objective and subjective methods have been used in the past to assess workplace fatigue, but little is known about correlations between them. We examine correlations between subjective and objective measures, including measures collected in a workplace scenario. Methods: 15 young and 17 older participants were assessed before and after work with four types of fatigue measure: objective physical (posturography), objective mental (psychomotor vigilance task), subjective physical and mental (self-assessment), objective and subjective realistic (oculomotor behaviour, observer-rated facial expression, typing performance). Results: Pre- and post-test scores were analysed with an ANOVA, significant differences were submitted to a factor analysis. It yielded three factors: one representing posturography, the second self-rated mental and physical fatigue and the third observer-rated facial expression. Conclusions: Results advocate the existence of three independent fatigue components: Objective physical fatigue, introspective and extrospective fatigue.
Practitioner Summary: This study analyses correlations between different subjective and objective fatigue markers to better understand the complex nature of workplace fatigue. Measurements were conducted directly at the workplace. Results reveal that fatigue comprises three independent fatigue components: Objective physical fatigue, introspective and extrospective fatigue. 相似文献
29.
30.
J��r?me Schmid Jos�� A. Iglesias?Guiti��n Enrico Gobbetti Nadia Magnenat-Thalmann 《The Visual computer》2011,27(2):85-95
Despite the ability of current GPU processors to treat heavy parallel computation tasks, its use for solving medical image
segmentation problems is still not fully exploited and remains challenging. A lot of difficulties may arise related to, for
example, the different image modalities, noise and artifacts of source images, or the shape and appearance variability of
the structures to segment. Motivated by practical problems of image segmentation in the medical field, we present in this
paper a GPU framework based on explicit discrete deformable models, implemented over the NVidia CUDA architecture, aimed for
the segmentation of volumetric images. The framework supports the segmentation in parallel of different volumetric structures
as well as interaction during the segmentation process and real-time visualization of the intermediate results. Promising
results in terms of accuracy and speed on a real segmentation experiment have demonstrated the usability of the system. 相似文献