首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   135篇
  免费   15篇
  国内免费   1篇
电工技术   4篇
化学工业   13篇
金属工艺   4篇
机械仪表   7篇
建筑科学   3篇
矿业工程   1篇
能源动力   11篇
轻工业   27篇
水利工程   1篇
无线电   17篇
一般工业技术   26篇
冶金工业   5篇
原子能技术   1篇
自动化技术   31篇
  2024年   1篇
  2023年   5篇
  2022年   6篇
  2021年   11篇
  2020年   11篇
  2019年   6篇
  2018年   10篇
  2017年   10篇
  2016年   13篇
  2015年   5篇
  2014年   6篇
  2013年   13篇
  2012年   16篇
  2011年   5篇
  2010年   7篇
  2009年   7篇
  2008年   2篇
  2007年   2篇
  2005年   1篇
  2004年   2篇
  2003年   3篇
  2002年   1篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
排序方式: 共有151条查询结果,搜索用时 11 毫秒
31.
提出一种基于提升二进小波变换的检测人脸部位(如鼻子、眼睛和嘴唇等)的快速算法。在提升二进小波滤波器中的自由参数是学习的,从便使两个向量(其中一个向量的分量是提升二进小波滤波器系数,另一个向量的分量是人脸某部位像素)之间的夹角的余弦值最大化。学习得到的滤波器应用到测试图像中,可以检测人脸某些部位。实验结果表明,该方法具有较强的鲁棒性,能够很好地解决复杂背景下的人脸检测问题。由于该方法实现的简单性,并容易由硬件实现,使得检测速度进一步提高,因此该方法在可视电话等领域有着广阔的应用前景。  相似文献   
32.
Microsystems technology is an emerging technology that is used in ever more technical systems, such as inkjet nozzles or accelerometers. 3D micromechanical structures became feasible by miniaturizing macromechanical elements. One big challenge in downsizing mechanical elements is to adapt conventional manufacturing technologies to the conditions of microtechnology. Integrated design and production processes must be suited to the new requirements, in-depth knowledge of production technology is required to design micromechanical components. Since 2000, the Collaborative Research Center 499 “Design, Production and Quality Assurance of Molded Microcomponents made of Metallic and Ceramic Materials” has been focusing on a continuous and stable process chain for molded micro components (Albers et al. 2005, Microsyst Technol). The aim of prior funding periods was to develop the knowledge about how components, such as gearwheels, and systems, such as micro gears, can be designed. Present research is focused on how to design functional elements, i.e. shaft-hub joints to transmit torque. This paper will introduce an approach that generates know-how via testing several plain bearings and shaft-hub joints in order to derive the necessary know-how to develop simulation tools later on.  相似文献   
33.
A country’s economy heavily depends on agricultural development. However, due to several plant diseases, crop growth rate and quality are highly suffered. Accurate identification of these diseases via a manual procedure is very challenging and time-consuming because of the deficiency of domain experts and low-contrast information. Therefore, the agricultural management system is searching for an automatic early disease detection technique. To this end, an efficient and lightweight Deep Learning (DL)-based framework (E-GreenNet) is proposed to overcome these problems and precisely classify the various diseases. In the end-to-end architecture, a MobileNetV3Small model is utilized as a backbone that generates refined, discriminative, and prominent features. Moreover, the proposed model is trained over the PlantVillage (PV), Data Repository of Leaf Images (DRLI), and a new Plant Composite (PC) dataset individually, and later on test samples, its actual performance is evaluated. After extensive experimental analysis, the proposed model obtained 1.00%, 0.96% and 0.99% accuracies on all three included datasets. Moreover, the proposed method achieves better inference speed when compared with other State-Of-The-Art (SOTA) approaches. In addition, a comparative analysis is conducted where the proposed strategy shows tremendous discriminative scores as compared to the various pre-trained models and other Machine Learning (ML) and DL methods.  相似文献   
34.
A threonine to isoleucine polymorphism at amino acid 164 in the fourth transmembrane spanning domain of the beta 2-adrenergic receptor (beta 2AR) is known to occur in the human population. The functional consequences of this polymorphism to catecholamine signaling in relevant cells or to end-organ responsiveness, however, are not known. To explore potential differences between the two receptors, site-directed mutagenesis was carried out to mimic the polymorphism. Transgenic FVB/N mice were then created overexpressing wild-type (wt) beta 2AR or the mutant Ile-164 receptor in a targeted manner in the heart using a murine alpha myosin heavy chain promoter. The functional properties of the two receptors were then assessed at the level of in vitro cardiac myocyte signaling and in vivo cardiac responses in intact animals. The expression levels of these receptors in the two lines chosen for study were approximately 1200 fmol/mg protein in cardiac membranes, which represents a approximately 45-fold increase in expression over endogenous beta AR. Myocyte membrane adenylyl cyclase activity in the basal state was significantly lower in the Ile-164 mice (19.5 +/- 2.7 pmol/min/mg) compared with wt beta 2AR mice (35.0 +/- 4.1 pmol/min/mg), as was the maximal isoproterenol-stimulated activity (49.8 +/- 7.8 versus 77.1 +/ 7.3 pmol/min/mg). In intact animals, resting heart rate (441 +/- 21 versus 534 +/- 17 bpm) and dP/dtmax (10,923 +/- 730 versus 15,308 +/- 471 mmHg/sec) were less in the Ile-164 mice as compared with wt beta 2AR mice. Similarly, the physiologic responses to infused isoproterenol were notably less in the mutant expressing mice. Indeed, these values, as well as other contractile parameters, were indistinguishable between Ile-164 mice and nontransgenic littermates. Taken together, these results demonstrate that the Ile-164 polymorphism is substantially dysfunctional in a relevant target tissue, as indicated by depressed receptor coupling to adenylyl cyclase in myocardial membranes and impaired receptor mediated cardiac function in vivo. Under normal homeostatic conditions or in circumstances where sympathetic responses are compromised due to diseased states, such as heart failure, this impairment may have important pathophysiologic consequences.  相似文献   
35.
In this paper, blocks for the thermal management of Li-ion battery are prepared. The blocks are made of paraffin wax, which is used as a phase change material (PCM), and graphite flakes. The process starts by compacting expanded graphite into the desired modular shapes and then impregnating it into molten paraffin wax. The modular pieces were assembled together, followed by finishing operations to achieve a desired packaging geometry.Thermo-mechanical properties of the produced phase change material–expanded graphite (PCM/EG) composites have been studied. The tests include thermal conductivity, tensile compression and bursting test. The results showed that as mass fraction of paraffin wax increases in the composite material, the thermal conductivity, tensile strength, compression strength, and burst strength were improved while tested at low operating temperatures. In contrast, the results showed reverse behaviors when tested at relatively high operating temperature.  相似文献   
36.
A series of poly(DL-lactide-co-glycolic acid) (PLGA) with poly(vinylalcohol-co-ethylene) (PEVAL) blends were prepared by solution casting method. The miscibility, thermal and mechanical properties have been investigated using FTIR, DSC, and DMA techniques. The miscibility of this pair of polymers throughout compositions was proved by these methods through the single Tg and the presence of interactions between the constituents. The TGA analysis revealed three degradation zones and no sensible enhancement in the thermal stability of PLGA was noted with addition of PEVAL content. The SEM analysis revealed that the draying method dramatically influence the surface morphology of copolymers and blend. The cross section micrograph of blend scaffold containing 50 wt% of PEVAL presents microcavities of diameter pores ranged between 70 and 170 µm interconnected and uniformly distributed in the polymer matrix.  相似文献   
37.
Ti3SiC2 was elaborated by two different methods: (i) Spark plasma sintering of 5Ti/2SiC/C powders and (ii) mechanical alloying of powders followed by Spark plasma sintering. The results showed that mechanical alloying was not advantageous for pure Ti3SiC2 formation but it can significantly improve the density of the obtained bulk material via the particles refinement as well as the microhardness by increasing the TiC content. It was found that the relative density was increased up to 98.58% for the sintered mechanically alloyed sample whereas it was not more than 96.04% for the sintered 5Ti/2SiC/C starting powders. The Vickers microhardness measured for both bulk samples demonstrates a high improvement for the previously mechanically alloyed powder mixture, as it was of about 1282 Hv and only 581.2 Hv for the alloy obtained from 5Ti/2SiC/C starting powders.  相似文献   
38.
The essential oils composition of coriander (Coriandrum sativum L.) fruits obtained by hydrodistillation was studied at three stages of maturity by GC–FID and GC–MS. Essential oil yields showed marked increase during maturation process and forty one compounds were identified. Geranyl acetate (46.27%), linalool (10.96%), nerol (1.53%) and neral (1.42%) were the main compounds at the first stage of maturity (immature fruits). At the middle stage, linalool (76.33%), cis-dihydrocarvone (3.21%) and geranyl acetate (2.85%) were reported as the main constituents. Essential oils at the final stage of maturity (mature fruits) consist mainly on linalool (87.54%) and cis-dihydrocarvone (2.36%). Additionally, accumulation of monoterpene alcohols and ketones was observed during maturation process of coriander fruit.  相似文献   
39.
Sarcopenia is characterised by an age-related decrease in the number of muscle fibres and additional weakening of the remaining fibres, resulting in a reduction in muscle mass and function. Many studies associate poor maternal nutrition during gestation and/or lactation with altered skeletal muscle homeostasis in the offspring and the development of sarcopenia. The aim of this study was to determine whether the musculoskeletal physiology in offspring born to mouse dams fed a low-protein diet during pregnancy was altered and whether any physiological changes could be modulated by the nutritional protein content in early postnatal stages. Thy1-YFP female mice were fed ad libitum on either a normal (20%) or a low-protein (5%) diet. Newborn pups were cross-fostered to different lactating dams (maintained on a 20% or 5% diet) to generate three groups analysed at weaning (21 days): Normal-to-Normal (NN), Normal-to-Low (NL) and Low-to-Normal (LN). Further offspring were maintained ad libitum on the same diet as during lactation until 12 weeks of age, creating another three groups (NNN, NLL, LNN). Mice on a low protein diet postnatally (NL, NLL) exhibited a significant reduction in body and muscle weight persisting up to 12 weeks, unlike mice on a low protein diet only prenatally (LN, LNN). Muscle fibre size was reduced in mice from the NL but not LN group, showing recovery at 12 weeks of age. Muscle force was reduced in NLL mice, concomitant with changes in the NMJ site and changes in atrophy-related and myosin genes. In addition, μCT scans of mouse tibiae at 12 weeks of age revealed changes in bone mass and morphology, resulting in a higher bone mass in the NLL group than the control NNN group. Finally, changes in the expression of miR-133 in the muscle of NLL mice suggest a regulatory role for this microRNA in muscle development in response to postnatal diet changes. Overall, this data shows that a low maternal protein diet and early postnatal life low-protein intake in mice can impact skeletal muscle physiology and function in early life while postnatal low protein diet favours bone integrity in adulthood.  相似文献   
40.
Fresh blueberries are highly perishable and must be preserved by either freezing or drying technologies. However, moisture impermeability of their skin is a barrier against the moisture diffusion slowing down the drying process. The aim of this study was to investigate the impact of liquid nitrogen pretreatments on osmotic dehydration kinetics of two blueberry species, Vaccinium corymbosum L. and Vaccinium angustifolium Ait, and on the physicochemical quality of dehydrated fruits.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号