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91.
Thermostability of the enzymes is influenced by the different parameters and pressure also influences the biological activity of the enzymes. Recently reported maltogenic α‐amylase from Aspergillus niger acts optimally on starch at 40°C and it was unstable above 40°C at atmospheric pressure. Calcium could stabilize the maltogenic α‐amylase activity up to 50°C at atmospheric pressure. But, at negative pressure (−200 mbar) enzyme was stable at temperatures higher than 50°C either in the presence or absence of the substrate, starch making it adoptable for starch processing. Enzyme showed higher affinity to the starch at negative pressure compared to the atmospheric pressure and change in the surface roughness of the enzyme is almost similar to the native state at 70°C and negative pressure. These results suggest that thermolabile enzymes can be used at negative pressures for industrial applications. 相似文献
92.
93.
Heinz Kaminski Thomas A. J. Kuhlbusch Heinz Fissan Lavanya Ravi Hans-Georg Horn Hee-Siew Han 《Aerosol science and technology》2013,47(6):708-716
The charge distributions of an improved opposed flow unipolar diffusion charger were measured using a tandem differential mobility analyzer (DMA) set up in a size range of approximately 20–400 nm. The charger is intended to be used in a portable aerosol sizer to measure particle size distributions. The determined charge distributions were represented by lognormal distributions, and a set of equations and coefficients was developed to calculate the charge distributions. These equations can be easily implemented in software for size distribution measurements. The agreement between the mathematically derived and measured charge distributions is very good, with regression coefficients R 2 > 0.96. The investigations showed that approximately 55% of 20-nm particles remain uncharged, while up to 25 elementary charges need to be considered for multiple charge correction of 400-nm particles. Comparison with the Fuchs theory delivered satisfying agreement with the measured average charge levels, but charge distributions cannot be described by the Fuchs theory, likely caused by the charger geometry. Copyright 2012 American Association for Aerosol Research 相似文献
94.
Assessment of the performance of different compost models to manage urban household organic solid wastes 总被引:2,自引:1,他引:1
P. Ravi Kumar Ambika Jayaram R. K. Somashekar 《Clean Technologies and Environmental Policy》2009,11(4):473-484
The environmental, cultural, socio-economic and political conditions of each community greatly affect the municipality’s effort
and decision-making in managing household wastes. Composting at home can be used as a sound method of SWM, can manage the
waste at source itself thereby can increase their recycling. And vermicomposting is a viable and completely feasible option
at household level, provided it is acceptable to family members to handle the worms and to remove worm-casts subsequently.
In this regard, the present paper gives a methodological framework for assessing the management of urban household organic
wastes using different compost models to influence the actual efficiency and effectiveness of a municipality’s collection
and management services. The current study also deals with the challenges of solid waste management with a focus on the segregation
of compostable wastes from the non-compostable ones and their composting, recycling or disposal. The non-compostable wastes
can be left for recycling and re-use by the concerned authorities. The composting behavior and the efficiency of different
compost models have been dealt with, and it is concluded that vermicomposting model is the best option. Urban residents can
be educated to vermicompost not only their entire kitchen wastes but also garden wastes to reduce the burden on the municipal
councils. 相似文献
95.
Ravi Kishore Ivaturi 《电子与电脑》2009,(3):32-34
低价位新车打入印度汽车市场,印度的汽车总数将于2012年超过4000万辆。空气质量已成为印度政府关注的首要课题,而针对省油引擎管理系统的重要性, 相似文献
96.
M. Ravi Sankar V.K. Jain J. Ramkumar 《International Journal of Machine Tools and Manufacture》2010,50(7):637-650
The present study focus on abrasive flow finishing (AFF), a process that finishes complex internal and external geometries with the help of viscoelastic abrasive medium, while keeping in mind its low finish and material removal rates (MRR). Researchers have often strived to improve finishing rate and MRR. As an attempt to overcome the said limitations, this paper discusses rotational abrasive flow finishing (R-AFF) process wherein complete tooling is externally rotated and the medium reciprocates with the help of hydraulic actuators. In this study, preliminary experiments are conducted on Al alloy and Al alloy/SiC metal matrix composites (MMCs) at different extrusion pressures, and medium compositions are employed for finding optimum conditions of the same for higher change in roughness (ΔRa). The same optimum conditions are used to study the effect of workpiece rotational speed on (ΔRa), material removal (MR), change in workpiece hardness and surface topology. It is noted that as the workpiece rotational speed increases from 2 to 10 RPM, the experimental helix angle decreases from 22° to 9° and the helical path length increases from 67 to 160 mm. Based on these findings the mechanism of material removal of matrix and reinforcement in MMC using R-AFF have been proposed. Here the matrix material is removed by micro-cutting and three methods of material removal mechanisms for reinforcement are also explained. The scientific logic behind finishing mechanism of matrix and reinforcement, cross hatch patterns, helical path directions, micro-scratch (μ-scratch) width and depth variation with size, orientation and support that active abrasive grain obtains from neighboring abrasives is derived from scanning electron microscopy micrographs. Finally this study establishes that R-AFF can produce 44% better ΔRa and 81.8% more MR compared to the AFF process. Accordingly, R-AFF generates micro cross hatch pattern on the finished surface that can improve lubricant holding capabilities. 相似文献
97.
Eleftherios E. Gdoutos Ravi Agrawal Horacio D. Espinosa 《International journal for numerical methods in engineering》2010,84(13):1541-1551
Ionic compounds pose extra challenges with the appropriate modeling of long‐range coulombic interactions. Here, we study the mechanical properties of zinc oxide (ZnO) nanowires using molecular dynamic simulations with Buckingham potential and determine the suitability of the Ewald (Ann. Phys. 1921; 19) and Wolf (J. Chem. Phys. 1999; 110 (17):8254–8282) summation methods to account for the long‐range Coulombic forces. A comparative study shows that both the summation methods are suitable for modeling bulk structures with periodic boundary conditions imposed on all sides; however, significant differences are observed when nanowires with free surfaces are modeled. As opposed to Wolf's prediction of a linear stress–strain response in the elastic regime, Ewald's method predicts an erroneous behavior. This is attributed to the Ewald method's inability to account for surface effects properly. Additionally, Wolf's method offers highly improved computational performance as the model size is increased. This gain in computational time allows for modeling realistic nanowires, which can be directly compared with the existing experimental results. We conclude that the Wolf summation is a superior technique when modeling non‐periodic structures in terms of both accuracy of the results and computational performance. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
98.
A new technique for managing and disseminating Web-based email prefetches messages and generates dynamic pages, displaying them at the network edge. Compared to other popular Web-based email servers, the prefetching and caching emails (PACE) prototype shows an improved performance with respect to user-perceived latency. Additionally, PACE'S centralized neural-network-based personalized spam filter will filter spam and viruses at the server's origin, thus saving bandwidth. Another major concern for users is the email accounts being clogged with spam. Spam filters can be classified as server-side or client-side. Server-side filters are integrated with email servers and filter out spam at the server end. 相似文献
99.
Intelligent agents in electronic markets for information goods: customization, preference revelation and pricing 总被引:4,自引:0,他引:4
Electronic commerce has enabled the use of intelligent agent technologies that can evaluate buyers, customize products, and price in real-time. Our model of an electronic market with customizable products analyzes the pricing, profitability and welfare implications of agent-based technologies that price dynamically based on product preference information revealed by consumers. We find that in making the trade-off between better prices and better customization, consumers invariably choose less-than-ideal products. Furthermore, this trade-off has a higher impact on buyers on the higher end of the market and causes a transfer of consumer surplus towards buyers with a lower willingness to pay. As buyers adjust their product choices in response to better demand agent technologies, seller revenues decrease since the gains from better buyer information are dominated by the lowering of the total value created from the transactions. We study the strategic and welfare implications of these findings, and discuss managerial and technology development guidelines. 相似文献
100.