全文获取类型
收费全文 | 211篇 |
免费 | 11篇 |
国内免费 | 5篇 |
专业分类
综合类 | 3篇 |
化学工业 | 60篇 |
金属工艺 | 5篇 |
机械仪表 | 7篇 |
建筑科学 | 7篇 |
能源动力 | 16篇 |
轻工业 | 32篇 |
石油天然气 | 1篇 |
无线电 | 14篇 |
一般工业技术 | 38篇 |
冶金工业 | 9篇 |
原子能技术 | 2篇 |
自动化技术 | 33篇 |
出版年
2024年 | 3篇 |
2023年 | 5篇 |
2022年 | 22篇 |
2021年 | 28篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 11篇 |
2016年 | 8篇 |
2015年 | 1篇 |
2014年 | 9篇 |
2013年 | 19篇 |
2012年 | 16篇 |
2011年 | 11篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 8篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1994年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有227条查询结果,搜索用时 15 毫秒
31.
32.
Salma Sultan Walid Mottawea JuDong Yeo Riadh Hammami 《International journal of molecular sciences》2021,22(23)
Over the past decade, gut microbiota dysbiosis has been linked to many health disorders; however, the detailed mechanism of this correlation remains unclear. Gut microbiota can communicate with the host through immunological or metabolic signalling. Recently, microbiota-released extracellular vesicles (MEVs) have emerged as significant mediators in the intercellular signalling mechanism that could be an integral part of microbiota-host communications. MEVs are small membrane-bound vesicles that encase a broad spectrum of biologically active compounds (i.e., proteins, mRNA, miRNA, DNA, carbohydrates, and lipids), thus mediating the horizontal transfer of their cargo across intra- and intercellular space. In this study, we provide a comprehensive and in-depth discussion of the biogenesis of microbial-derived EVs, their classification and routes of production, as well as their role in inter-bacterial and inter-kingdom signaling. 相似文献
33.
Alhasan AH Kim DY Daniel WL Watson E Meeks JJ Thaxton CS Mirkin CA 《Analytical chemistry》2012,84(9):4153-4160
We report the development of a novel Scanometric MicroRNA (Scano-miR) platform for the detection of relatively low abundance miRNAs with high specificity and reproducibility. The Scano-miR system was able to detect 1 fM concentrations of miRNA in serum with single nucleotide mismatch specificity. Indeed, it provides increased sensitivity for miRNA targets compared to molecular fluorophore-based detection systems, where 88% of the low abundance miRNA targets could not be detected under identical conditions. The application of the Scano-miR platform to high density array formats demonstrates its utility for high throughput and multiplexed miRNA profiling from various biological samples. To assess the accuracy of the Scano-miR system, we analyzed the miRNA profiles of samples from men with prostate cancer (CaP), the most common noncutaneous malignancy and the second leading cause of cancer death among American men. The platform exhibits 98.8% accuracy when detecting deregulated miRNAs involved in CaP, which demonstrates its potential utility in profiling and identifying clinical and research biomarkers. 相似文献
34.
Karim BENYAHI Youcef BOUAFIA Salma BARBOURA Mohand Said KACHI 《Frontiers of Structural and Civil Engineering》2018,12(4):577-593
The present study goes into the search for the safety domain of civil engineering structures. The objective is to show how a reliability-evaluation brought by a mechanical sizing can be obtained. For that purpose, it is necessary to have a mechanical model and a reliability model representing correctly the behavior of this type of structure.It is a question on one hand, to propose a formulation for the nonlinear calculation (mechanical nonlinearity) of the spatial structures in trusses, and on the other hand, to propose or to adapt a formulation and a modeling of the reliability. The principle of Hasofer-Lind can be applied, in first approach, for the reliability index estimation, scenarios and the probability of failure.The made check concerned metallic in truss structures. Finally, some structures are calculated using the method adapted by Hasofer-Lind to validate the probability approach of the reliability analysis. 相似文献
35.
Shad Dowlatshahi 《国际生产研究杂志》2013,51(14):4199-4215
This paper explores the role of inbound and outbound transportation within the context of a reverse logistics (RL) system. The transportation system is analysed and evaluated in terms of specific subsystems (sub-factors) associated with it. The data was collected from two in-depth case studies from two different industries. The research methodology utilised in this study is exploratory case study approach. The analysis of these case studies resulted in propositions and insights regarding RL practices with respect to a transportation system. The transportation sub-factors, propositions, and a framework for effective design and implementation of RL operations with respect to the transportation system are then presented. In conclusion, the results, managerial implications, and future research results are provided. 相似文献
36.
Nanospherical titanium oxide with anatase structure was obtained at low temperature and normal pressure using a simple method of preparation. The dilute titanium (III) chloride solution was stirred at room temperature for several hours, and then ammonium hydroxide with hydrogen peroxide was added. A yellow gel TiO2·xH2O was obtained with nanodot shape and amorphous structure. Heated at 300 °C, it crystallized to pure anatase structure with nanospherical shape. The anatase particles prepared show good adsorption and photodegradation of Congo red solution under the sunlight. Materials were characterized by powder X-ray diffraction, thermal analysis, transmission electron microscope and UV spectroscopy. 相似文献
37.
Ahmad I Ali Sheraz M Ahmed S Shad Z Vaid FH 《International journal of cosmetic science》2012,34(3):240-245
This study involves the evaluation of the effect of certain stabilizers, that is, citric acid (CT), tartaric acid (TA) and boric acid (BA) on the degradation of ascorbic acid (AH(2) ) in oil-in-water cream formulations exposed to the UV light and stored in the dark. The apparent first-order rate constants (0.34-0.95 × 10(-3) min(-1) in light, 0.38-1.24 × 10(-2) day(-1) in dark) for the degradation reactions in the presence of the stabilizers have been determined. These rate constants have been used to derive the second-order rate constants (0.26-1.45 × 10(-2) M(-1) min(-1) in light, 3.75-8.50 × 10(-3) M(-1) day(-1) in dark) for the interaction of AH(2) and the individual stabilizers. These stabilizers are effective in causing the inhibition of the rate of degradation of AH(2) both in the light and in the dark. The inhibitory effect of the stabilizers is in the order of CT > TA > BA. The rate of degradation of AH(2) in the presence of these stabilizers in the light is about 120 times higher than that in the dark. This could be explained on the basis of the deactivation of AH(2) -excited triplet state by CT and TA and by the inhibition of AH(2) degradation through complex formation with BA. AH(2) leads to the formation of dehydroascorbic acid (A) by chemical and photooxidation in cream formulations. 相似文献
38.
Kuehner R. Todd T.D. Shad F. Kezys V. 《Vehicular Technology, IEEE Transactions on》2001,50(4):1024-1038
We consider a base station, which communicates to a set of portable stations using a smart antenna operating in multibeam, packet-switched, space division multiple access (SDMA) mode. We assume that the system operates using time division duplexing (TDD) and focus on the problem of access to the stations by the base station in the forward-link direction. A polling protocol is used which permits efficient access in this type of system. The operation of the protocol is unique in that it permits dynamic slot allocation and accommodates variations in channel time coherence. In the protocol, dynamic slot assignment is integrated into the forward-link beam scheduling. This allows us to explore the value of dynamic station slot assignment when constructing the SDMA/TDMA frames. The results show the improvements in capacity, which are possible in such systems and give insight into the degradation in protocol performance that occurs when channel coherence times decrease. We find that very large improvements in capacity are possible using dynamic slot allocation, especially under harsh channel conditions. We also investigate various base station queueing issues in this type of system. It is shown that care must be taken in how buffering is performed so that blocking effects do not unnecessarily degrade the forward-link capacity 相似文献
39.
Plants have various self-defense mechanisms against biotic attacks, involving both physical and chemical barriers. Physical barriers include spines, trichomes, and cuticle layers, whereas chemical barriers include secondary metabolites (SMs) and volatile organic compounds (VOCs). Complex interactions between plants and herbivores occur. Plant responses to insect herbivory begin with the perception of physical stimuli, chemical compounds (orally secreted by insects and herbivore-induced VOCs) during feeding. Plant cell membranes then generate ion fluxes that create differences in plasma membrane potential (Vm), which provokes the initiation of signal transduction, the activation of various hormones (e.g., jasmonic acid, salicylic acid, and ethylene), and the release of VOCs and SMs. This review of recent studies of plant–herbivore–infection interactions focuses on early and late plant responses, including physical barriers, signal transduction, SM production as well as epigenetic regulation, and phytohormone responses. 相似文献
40.
The modification of plastics to generate germ-reducing surface materials is a promising strategy to decrease nosocomial infections in hygiene-sensitive areas. In this paper, photocatalytically active nanoparticles were incorporated as additives, not as a coating, into silicone rubber matrix material to produce elastic antibacterial bulk materials. Samples with 5 wt% and 10 wt% of two different types of TiO2 and ZnO were prepared and investigated. The thermal analysis of the developed materials showed a complete vulcanization of the developed materials and slight modifications of mechanical properties were found. Investigations of the surface of the materials indicated no changes in the wettability of the surfaces or in their fourier transform infrared spectrometer (FT-IR) spectra, suggesting no degradation of the developed material. The photocatalytic activity on the surface of the test samples was investigated by microbial tests with Escherichia coli, Pseudomonas fluorescens, and Staphylococcus aureus bacteria. Depending on the additive type and the test germs, the samples showed different intensities of a germ-reducing effect (up to >99,999%). 相似文献