全文获取类型
收费全文 | 2167篇 |
免费 | 77篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 39篇 |
综合类 | 3篇 |
化学工业 | 435篇 |
金属工艺 | 51篇 |
机械仪表 | 51篇 |
建筑科学 | 42篇 |
矿业工程 | 3篇 |
能源动力 | 103篇 |
轻工业 | 117篇 |
水利工程 | 6篇 |
石油天然气 | 17篇 |
无线电 | 353篇 |
一般工业技术 | 483篇 |
冶金工业 | 298篇 |
原子能技术 | 21篇 |
自动化技术 | 234篇 |
出版年
2023年 | 20篇 |
2022年 | 44篇 |
2021年 | 68篇 |
2020年 | 51篇 |
2019年 | 43篇 |
2018年 | 82篇 |
2017年 | 67篇 |
2016年 | 59篇 |
2015年 | 37篇 |
2014年 | 79篇 |
2013年 | 151篇 |
2012年 | 100篇 |
2011年 | 101篇 |
2010年 | 68篇 |
2009年 | 80篇 |
2008年 | 81篇 |
2007年 | 93篇 |
2006年 | 69篇 |
2005年 | 45篇 |
2004年 | 49篇 |
2003年 | 49篇 |
2002年 | 55篇 |
2001年 | 34篇 |
2000年 | 32篇 |
1999年 | 42篇 |
1998年 | 98篇 |
1997年 | 61篇 |
1996年 | 53篇 |
1995年 | 51篇 |
1994年 | 39篇 |
1993年 | 32篇 |
1992年 | 32篇 |
1991年 | 27篇 |
1990年 | 29篇 |
1989年 | 17篇 |
1988年 | 26篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 14篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 20篇 |
1975年 | 6篇 |
1973年 | 11篇 |
排序方式: 共有2256条查询结果,搜索用时 15 毫秒
31.
Ramit Debnath Ronita Bardhan Rangan Banerjee 《Clean Technologies and Environmental Policy》2017,19(3):705-719
In this study, we attempt to mitigate household air pollution (HAP) through improved kitchen design. Field surveys were conducted in ten kitchens of rural western India, which were then modelled and simulated for dynamic indoor airflow network analysis. The simulated results were statistically clustered using principal component analysis and hierarchical agglomerative clustering, to construct a cumulative built environment parameter called ‘Built Factor’ for each kitchen, and subsequently a derivative matrix was developed. Categorization of better performing kitchens from this derivative matrix enabled in deriving the built parameter thresholds for a ‘better’ kitchen design. This derived kitchen showed 60 % reduction in PM2.5 peak concentration during cooking hours. The evaluation described here is essentially a “proof of concept”, that effective building design can be an alternative way to reduce HAP without the introduction of chimneys, improved cookstoves or shifting to cleaner fuel. 相似文献
32.
Memory Devices: Eliminating Negative‐SET Behavior by Suppressing Nanofilament Overgrowth in Cation‐Based Memory (Adv. Mater. 48/2016) 下载免费PDF全文
33.
The formation of all‐organic dual spin valves (DSVs) with three organic spin‐selective layers, that is, spin‐injection, spin‐detection, and an additional spin‐filtering layer at the intermediate, is reported. As spin‐selective layers, manganese‐ and cobalt phthalocyanines, which are well‐known single‐molecule magnets, are used in their immobilized forms, so that all‐organic DSVs can be prefabricated for characterization. The three spin‐selective layers have provided four configurations with at most two spin‐flip interfaces enforcing spin‐flipping at the two nonmagnetic organic spacer layers, for which copper phthalocyanine is used. Since a couple of the four configurations have exhibited similar resistivities, the degeneracy in the resistive‐states is broken through asymmetric spin‐injection and spin‐detection layers and also through asymmetric thickness of the nonmagnetic spacer layers. When both the spin‐flip interfaces are made operative independently, a 2‐bit logic with four distinct resistive states can be achieved. 相似文献
34.
Jani Das Ajit Paul Abraham Prakash C. Ghosh Rangan Banerjee 《Clean Technologies and Environmental Policy》2018,20(1):65-80
Electricity supply in India is from a centralized grid. Many parts of the country experience grid interruptions. Life cycle energy and environmental analysis has been done for a 27 kWp photovoltaic system which acts as grid backup for 3 h outage in an Indian urban residential scenario. This paper discusses energy requirements and carbon emission for a PV storage system for five different battery technologies in Indian context. This can be used as a metric for comparative analysis for new batteries, with an undeveloped market. The energy requirements for the components are quantified and are compared in terms of energy payback time (EPBT) and Net Energy Ratio (NER). All the calculations are done for Indian context. EPBT is found to be in the range of 2–4.5 years for all the systems, while NER is in the range of 6.6–2.52. NaS has the highest emission factor of 0.67 kgCO2/kWh and the least for NiCd (0.091 kgCO2/kWh). These factors can be used to select a PV battery option and to target selection of materials and systems based on the reported values. 相似文献
35.
The problem of accurately reconstructing a piecewise smooth. 2-periodic function f and its first few derivatives, given only a truncated Fourier series representation of f, is studied and solved. The reconstruction process is divided into two steps. In the first step, the first 2N + 1 Fourier coefficients of f are used to approximate the locations and magnitudes of the discontinuities in f and its first M derivatives. This is accomplished by first finding initial estimates of these quantities based on certain properties of Gibbs phenomenon, and then refining these estimates by fitting the asymptotic form of the Fourier coefficients to the given coefficients using a least-squares approach. The locations of the singularities are approximated to within O(N
–M–2), and the associated jump of the kth derivative of f is approximated to within O(N
–M–1+k
), as N , and the method is robust. These estimates are then used with a class of singular basis functions, which have certain built-in singularities, to construct a new sequence of approximations to f. Each of these new approximations is the sum of a piecewise smooth function and a new Fourier series partial sum. When N is proportional to M, it is shown that these new approximations, and their derivatives, converge exponentially in the maximum norm to f, and its corresponding derivatives, except in the union of a finite number of small open intervals containing the points of singularity of f. The total measure of these intervals decreases exponentially to zero as M . The technique is illustrated with several examples. 相似文献
36.
As manufacturing environments are getting distributed and increasing in size, the related virtual environments are getting
larger and more closely networked together. This trend has led to a new paradigm—large-scale virtual manufacturing environment
(LSVME). It supports networked and distributed virtual manufacturing to meet manufacturing system requirements. Since it contains
a large number of virtual components, an effective data structure and collaborative construction methodology are needed. A
metaearth architecture is proposed as the data structure for representing LSVME. This architecture consists of virtual space
layer, mapping layer, library layer and ontology layers, which describe interaction among virtual components and has the ability
to analyze the characteristics of virtual environment. In addition, it increases reusability of virtual components and supports
self-reconfiguration for manufacturing simulation. A heuristic construction method based on graph theory is proposed using
this architecture. It prevents redundant design of virtual components and contributes to an effective construction scheduling
technique for collaborative designers. 相似文献
37.
Kaushik Bhattacharyya Rakesh Biswas Anindya Sundar Dhar Swapna Banerjee 《Microprocessors and Microsystems》2010,34(2-4):96-101
A new scaled radix-4 CORDIC architecture that incorporates pipelining and parallelism is presented. The latency of the architecture is n/2 clock cycles and throughput rate is one valid result per n/2 clocks for n bit precision. A 16 bit radix-4 CORDIC architecture is implemented on the available FPGA platform. The corresponding latency of the architecture is eight clock cycles and throughput rate is one valid result per eight clock cycles. The entire scaled architecture operates at 56.96 MHz of clock rate with a power consumption of 380 mW. The speed can be enhanced with the upgraded version of FPGA device. A speed-area optimized processor is obtained through this architecture and is suitable for real time applications. 相似文献
38.
We propose a new link metric called normalized advance (NADV) for geographic routing in multihop wireless networks. NADV selects neighbors with the optimal trade-off between proximity and link cost. Coupled with the local next hop decision in geographic routing, NADV enables an adaptive and efficient cost-aware routing strategy. Depending on the objective or message priority, applications can use the NADV framework to minimize various types of link cost.We present efficient methods for link cost estimation and perform detailed experiments in simulated environments. Our results show that NADV outperforms current schemes in many aspects: for example, in high noise environments with frequent packet losses, the use of NADV leads to 81% higher delivery ratio. When compared to centralized routing under certain settings, geographic routing using NADV finds paths whose cost is close to the optimum. We also conducted experiments in Emulab testbed and the results demonstrate that our proposed approach performs well in practice. 相似文献
39.
Bhattacharya D Saha S Basu S Chakravarty S Chakravarty A Banerjee D Chakrabarti A 《Proteomics. Clinical applications》2010,4(5):480-488
Purpose: In (hemoglobin, Hb) HbEβ‐thalassemia, HbE (β‐26 Glu→Lys) interacts with β‐thalassemia to produce clinical manifestation of varying severity. This is the first proteomic effort to study changes in protein levels of erythrocytes isolated from HbEβ‐thalassemic patients compared to normal. Experimental design: We have used 2‐DE and MALDI‐MS/MS‐based techniques to investigate the differential proteome profiling of membrane and Hb‐depleted fraction of cytosolic proteins of erythrocytes isolated from the peripheral blood samples of HbEβ‐thalassemia patients and normal volunteers. Results: Our study showed that redox regulators such as peroxiredoxin 2, Cu‐Zn superoxide dismutase and thioredoxin and chaperones such as α‐hemoglobin stabilizing protein and HSP‐70 were upregulated in HbEβ‐thalassemia. We have also observed larger amounts of membrane associated globin chains and indications of disruption of spectrin‐based junctional complex in the membrane skeleton of HbEβ‐thalassemic erythrocytes upon detection of low molecular weight fragments of β‐spectrin and decrease in β‐actin and dematin content. Conclusion and clinical relevance: We have observed interesting changes in the proteomic levels of redox regulators and chaperons in the thalassemic hemolysates and have observed strong correlation or association of the extent of such proteomic changes with HbE levels. This could be important in understanding the role of HbE in disease progression and pathophysiology. 相似文献
40.
Bikash K. Behera Anindita Banerjee Prasanta K. Panigrahi 《Quantum Information Processing》2017,16(12):312
Quantum cheques could be a forgery-free way to make transaction in a quantum networked banking system with perfect security against any no-signalling adversary. Here, we demonstrate the implementation of quantum cheque, proposed by Moulick and Panigrahi (Quantum Inf Process 15:2475–2486, 2016), using the five-qubit IBM quantum computer. Appropriate single qubit, CNOT and Fredkin gates are used in an optimized configuration. The accuracy of implementation is checked and verified through quantum state tomography by comparing results from the theoretical and experimental density matrices. 相似文献