全文获取类型
收费全文 | 1128篇 |
免费 | 55篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 271篇 |
金属工艺 | 26篇 |
机械仪表 | 24篇 |
建筑科学 | 17篇 |
能源动力 | 54篇 |
轻工业 | 95篇 |
水利工程 | 5篇 |
石油天然气 | 4篇 |
无线电 | 135篇 |
一般工业技术 | 234篇 |
冶金工业 | 154篇 |
原子能技术 | 12篇 |
自动化技术 | 138篇 |
出版年
2023年 | 12篇 |
2022年 | 34篇 |
2021年 | 27篇 |
2020年 | 32篇 |
2019年 | 21篇 |
2018年 | 55篇 |
2017年 | 43篇 |
2016年 | 39篇 |
2015年 | 30篇 |
2014年 | 42篇 |
2013年 | 89篇 |
2012年 | 45篇 |
2011年 | 43篇 |
2010年 | 36篇 |
2009年 | 56篇 |
2008年 | 26篇 |
2007年 | 30篇 |
2006年 | 37篇 |
2005年 | 17篇 |
2004年 | 18篇 |
2003年 | 22篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 20篇 |
1999年 | 17篇 |
1998年 | 39篇 |
1997年 | 23篇 |
1996年 | 34篇 |
1995年 | 15篇 |
1994年 | 19篇 |
1993年 | 22篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 16篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1974年 | 5篇 |
排序方式: 共有1183条查询结果,搜索用时 31 毫秒
91.
Rajesh Kumar Gayatri Sahu Shailendra K. Saxena Hari M. Rai Pankaj R. Sagdeo 《SILICON》2014,6(2):117-121
A qualitative evolution of an asymmetric Raman line-shape function from a Lorentzian line-shape is discussed here for application in low dimensional semiconductors. The step-by-step evolution reported here is based on the phonon confinement model which is successfully used in literature to explain the asymmetric Raman line-shape from semiconductor nanostructures. Physical significance of different terms in the theoretical asymmetric Raman line-shape has been explained here. Better understanding of theoretical reasoning behind each term allows one to use the theoretical Raman line-shape without going into the details of theory from first principle. This will enable one to empirically derive a theoretical Raman line-shape function for any material if information about its phonon dispersion relation, size dependence, etc., is known. 相似文献
92.
Structure‐Guided Design of Thiazolidine Derivatives as Mycobacterium tuberculosis Pantothenate Synthetase Inhibitors
下载免费PDF全文
![点击此处可从《ChemMedChem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Parthiban Brindha Devi Ganesh Samala Jonnalagadda Padma Sridevi Shalini Saxena Mallika Alvala Elena G. Salina Prof. Dharmarajan Sriram Prof. Perumal Yogeeswari 《ChemMedChem》2014,9(11):2538-2547
The pantothenate biosynthetic pathway is essential for the persistent growth and virulence of Mycobacterium tuberculosis (Mtb) and one of the enzymes in the pathway, pantothenate synthetase (PS, EC: 6.3.2.1), encoded by the panC gene, has become an appropriate target for new therapeutics to treat tuberculosis. Herein, we report nanomolar thiazolidine inhibitors of Mtb PS developed by a rational inhibitor design approach. The thiazolidine compounds were discovered by using energy‐based pharmacophore modelling and subsequent in vitro screening, which resulted in compounds with a half maximal inhibitory concentration (IC50) value of (1.12±0.12) μM . These compounds were subsequently optimised by a combination of modelling and synthetic chemistry. Hit expansion of the lead by chemical synthesis led to an improved inhibitor with an IC50 value of 350 nM and an Mtb minimum inhibitory concentration (MIC) of 1.55 μM . Some of these compounds also showed good activity against dormant Mtb cells. 相似文献
93.
A New SiF–Dipropargyl Glycerol Scaffold as a Versatile Prosthetic Group to Design Dimeric Radioligands: Synthesis of the [18F]BMPPSiF Tracer to Image Serotonin Receptors
下载免费PDF全文
![点击此处可从《ChemMedChem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Puja Panwar Hazari Dr. Jurgen Schulz Delphine Vimont Nidhi Chadha Prof. Michele Allard Dr. Magali Szlosek‐Pinaud Prof. Eric Fouquet Dr. Anil Kumar Mishra 《ChemMedChem》2014,9(2):337-349
A novel SiX–dipropargyl glycerol scaffold (X: H, F, or 18F) was developed as a versatile prosthetic group that provides technical advantages for the preparation of dimeric radioligands based on silicon fluoride acceptor pre‐ or post‐labeling with fluorine‐18. Rapid conjugation with the prosthetic group takes place in microwave‐assisted click conjugation under mild conditions. Thus, a bivalent homodimeric SiX–dipropargyl glycerol derivatized radioligand, [18F]BMPPSiF, with enhanced affinity was developed by using click conjugation. High uptake of the radioligand was demonstrated in 5‐HT1A receptor‐rich regions in the brain with positron emission tomography. Molecular docking studies (rigid protein–flexible ligand) of BMPPSiF and known antagonists (WAY‐100635, MPPF, and MefWAY) with monomeric, dimeric, and multimeric 5‐HT1A receptor models were performed, with the highest G score obtained for docked BMPPSiF: ?6.766 as compared with all three antagonists on the monomeric model. Multimeric induced‐fit docking was also performed to visualize the comparable mode of binding under in vivo conditions, and a notably improved G score of ?8.455 was observed for BMPPSiF. These data directly correlate the high binding potential of BMPPSiF with the bivalent binding mode obtained in the biological studies. The present study warrants wide application of the SiX–dipropargyl glycerol prosthetic group in the development of ligands for imaging with enhanced affinity markers for specific targeting based on peptides, nucleosides, and lipids. 相似文献
94.
A few aluminum containing polycarbosilanes named AlOR-PCS and Alac-PCS have been synthesized by the reaction of aluminum isopropoxide (AlOR) and aluminum acetylacetonate (Alac) with polycarbosilane (PCS), respectively. These materials were characterized by Fourier Transform Spectroscopy (FTIR), Thermo gravimetric Analysis (TGA) and Gel Permeation Chromatography (GPC). The rheological properties of these compounds were studied with respect to time, temperature and atmosphere (inert & air). It has been observed that the increase in metal content enhances the crosslinking of the PCS chains. Under similar conditions, the crosslinking of AlOR-PCS derivatives was found slower than Alac-PCS. GPC analysis of the samples showed the increase in molecular weight of these compounds compared to virgin PCS. TGA showed improved ceramic yield with increasing metal content. Alac-PCS gave higher ceramic yield than AlOR-PCS for similar molar ratios of metal complexes. 相似文献
95.
Cloud computing is a form of distributed computing, which promises to deliver reliable services through next‐generation data centers that are built on virtualized compute and storage technologies. It is becoming truly ubiquitous and with cloud infrastructures becoming essential components for providing Internet services, there is an increase in energy‐hungry data centers deployed by cloud providers. As cloud providers often rely on large data centers to offer the resources required by the users, the energy consumed by cloud infrastructures has become a key environmental and economical concern. Much energy is wasted in these data centers because of under‐utilized resources hence contributing to global warming. To conserve energy, these under‐utilized resources need to be efficiently utilized and to achieve this, jobs need to be allocated to the cloud resources in such a way so that the resources are used efficiently and there is a gain in performance and energy efficiency. In this paper, a model for energy‐aware resource utilization technique has been proposed to efficiently manage cloud resources and enhance their utilization. It further helps in reducing the energy consumption of clouds by using server consolidation through virtualization without degrading the performance of users’ applications. An artificial bee colony based energy‐aware resource utilization technique corresponding to the model has been designed to allocate jobs to the resources in a cloud environment. The performance of the proposed algorithm has been evaluated with the existing algorithms through the CloudSim toolkit. The experimental results demonstrate that the proposed technique outperforms the existing techniques by minimizing energy consumption and execution time of applications submitted to the cloud. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
96.
M. KaurAuthor Vitae Niranjan S. RamgirU.K. GautamAuthor Vitae S. Kailasa GanapathiAuthor VitaeS. BhattacharyaAuthor Vitae N. DattaAuthor VitaeV. Saxena A.K. DebnathAuthor VitaeD.K. AswalAuthor Vitae S.K. GuptaAuthor Vitae 《Materials Chemistry and Physics》2014
Gas sensing characteristics of SnO2 thin films prepared by RF sputtering have been investigated and compared to that of RGTO (Rheotaxially Grown and Thermally Oxidized) films. Both the sensor films exhibited a highly selective response towards H2S with RF sputtered film showing better response characteristics. RF sputtered and RGTO films exhibited a maximum response of 54 and 15 towards 10 ppm of H2S at an optimum operating temperature of 150 and 250 °C, respectively. Sputtered films exhibited a linear response in the wide concentration range from 500 ppb to 500 ppm while RGTO films were found to saturate for concentrations above 100 ppm. XPS investigations revealed that the RGTO films are more sub–stoichiometric or oxygen deficient than the sputtered films. Raman studies further indicates that the surface of sputtered and RGTO films are characterized by the presence of oxygen deficiency attributed to the “bridging-type” and deeper “in-plane/sub-bridging” oxygen vacancies, respectively. The improved response kinetics of the RF sputtered films is attributed to the presence of bridging type oxygen vacancies that facilitates the charge transfer between the sensor surface and H2S molecules. 相似文献
97.
Hima Saxena B. Bhattacharya Nitin A. Jadhav Vivek K. Singh Shashank Shukla Manish Dubey 《Journal of Experimental Nanoscience》2014,9(5):444-451
Electrical, structural and optical properties of a composite containing a polymer electrolyte (namely polyethylene oxide complexed with sodium iodide) and multiwall carbon nanotube (MWCNT) are reported. The films of these composites were ‘solution casted’ using the viscous solution of polyethylene oxide (PEO) complexed with sodium iodide (NaI) in desired ratios and characterised using various techniques. The conductivity versus composition plot in PEO:NaI shows conductivity maxima at 12?wt% NaI concentration while in MWCNTs doped polymer electrolyte it occurs at 40?wt% MWCNTs concentration. The surface morphology by scanning electron microscopy (SEM) shows the enhancement in amorphous reason by MWCNTs doping which is a well-known favourable condition for conductivity enhancement. The differential scanning calorimetry shows that dispersal of MWCNTs reduces the crystallinity of polymer electrolyte that is well-supported by our polarised optical micrographs and SEM measurements. 相似文献
98.
Lokesh Kumar Saxena Promod Kumar Jain 《The International Journal of Advanced Manufacturing Technology》2011,53(1-4):11-34
This paper addresses the dynamic cell formation problem (DCF). In dynamic environment, the product demand and mix changes in each period of a multiperiod planning horizon. It causes need of reconfiguration of cells to respond to the product demand and mix change in each period. This paper proposes a mixed-integer nonlinear programming model to design the dynamic cellular manufacturing systems (DCMSs) under dynamic environment. The proposed model, to the best of the author??s knowledge, is the most comprehensive model to date with more integrated approach to the DCMSs. The proposed DCMS model integrates concurrently the important manufacturing attributes in existing models in a single model such as machine breakdown effect in terms of machine repair cost effect and production time loss cost effect to incorporate reliability modeling; production planning in terms of part inventory holding, part internal production cost, and part outsourcing; process batch size; transfer batch size for intracell travel; transfer batch size for intercell travel; lot splitting; alternative process plan, and routing and sequence of operation; multiple copies of identical copies; machine capacity, cutting tooling requirements, work load balancing, and machine in different cells constraint; machine in same cell constraint; and machine procurements and multiple period dynamic cell reconfiguration. Further, the objective of the proposed model is to minimize the sum of various costs such as intracell movement costs; intercell movement costs and machine procurement costs; setup cost; cutting tool consumption costs; machine operation costs; production planning-related costs such as internal part production cost, part holding costs, and subcontracting costs; system reconfiguration costs; and machine breakdown repair cost, production time loss cost due to machine breakdown, machine maintenance overheads, etc. ,in an integrated manner. Nonlinear terms of objective functions are transformed into linear terms to make mixed-integer linear programming model. The proposed model has been demonstrated with several problems, and results have been presented accordingly. 相似文献
99.
100.
Recent research work conducted in China on heat transfer to immersed surfaces in bubbling and circulating fluidized beds, including coal combustors and boilers, is reviewed. Studies include measurements of heat-transfer coefficients (local and total) from horizontal and vertical tubes in bubbling fluidized beds and their variations with operating and system parameters. Special designs developed for heat-transfer probes and theoretical models for the computation of heat-transfer coefficients are discussed. Recent work is presented on circulating fluidized beds with emphasis on hydrodynamics and heat transfer. Proposed correlations and novel designs of thin-film heat-transfer and capacitance probes are included. 相似文献