全文获取类型
收费全文 | 3304篇 |
免费 | 113篇 |
国内免费 | 25篇 |
专业分类
电工技术 | 69篇 |
综合类 | 2篇 |
化学工业 | 714篇 |
金属工艺 | 109篇 |
机械仪表 | 89篇 |
建筑科学 | 49篇 |
矿业工程 | 4篇 |
能源动力 | 132篇 |
轻工业 | 160篇 |
水利工程 | 27篇 |
石油天然气 | 30篇 |
无线电 | 340篇 |
一般工业技术 | 743篇 |
冶金工业 | 510篇 |
原子能技术 | 43篇 |
自动化技术 | 421篇 |
出版年
2023年 | 49篇 |
2022年 | 70篇 |
2021年 | 99篇 |
2020年 | 105篇 |
2019年 | 81篇 |
2018年 | 97篇 |
2017年 | 115篇 |
2016年 | 104篇 |
2015年 | 72篇 |
2014年 | 116篇 |
2013年 | 272篇 |
2012年 | 126篇 |
2011年 | 176篇 |
2010年 | 145篇 |
2009年 | 139篇 |
2008年 | 140篇 |
2007年 | 140篇 |
2006年 | 106篇 |
2005年 | 72篇 |
2004年 | 67篇 |
2003年 | 67篇 |
2002年 | 63篇 |
2001年 | 47篇 |
2000年 | 49篇 |
1999年 | 47篇 |
1998年 | 112篇 |
1997年 | 84篇 |
1996年 | 57篇 |
1995年 | 61篇 |
1994年 | 75篇 |
1993年 | 32篇 |
1992年 | 28篇 |
1991年 | 27篇 |
1990年 | 32篇 |
1989年 | 25篇 |
1988年 | 28篇 |
1987年 | 23篇 |
1986年 | 23篇 |
1985年 | 29篇 |
1984年 | 28篇 |
1983年 | 18篇 |
1982年 | 15篇 |
1981年 | 14篇 |
1980年 | 19篇 |
1979年 | 15篇 |
1978年 | 15篇 |
1977年 | 21篇 |
1976年 | 29篇 |
1975年 | 15篇 |
1971年 | 10篇 |
排序方式: 共有3442条查询结果,搜索用时 15 毫秒
71.
The fate of [1-14C] linoleic acid and [1-14C] linolenic acid in the liver slices and also in the liver tissues of live carnivorous catfish,Heteropneustes fossilis andClarias batrachus, was studied. Incorporation of the fatty acids into different lipid classes in the live fish differed greatly from the tissue
slices, indicating certain physiological control operative in vivo. The extent of desaturation and chain elongation of linoleic
and linolenic acids into long-chain polyunsaturated fatty acids was low. Linolenic acid was oxidized (thus labeling the saturated
fatty acid with liberated14C-acetyl-CoA) in preference to linoleic acid, and this oxidation also seemed to be under physiological control since both
of the fatty acids were poorly oxidized in the tissue slices and in the killed fish. These fish can therefore recognize the
difference in the acyl chain structures of linoleate and linolenate. The higher oxidation of liolenic acid and poor capacity
for its conversion to longer chain, highly unsaturated derivatives indicates a higher demand for the dietary supply of these
essential fatty acids in these two species. 相似文献
72.
B. Chatterjee D. Mukhopadhyay A.K. Ghosh Pavlin Groudev 《Nuclear Engineering and Design》2009,239(3):559-565
Severe accident studies for very low frequency events for VVER-1000 (V320) are carried out to estimate in-vessel damage progression under steam-rich and starved conditions. The analyses with code ASTEC, jointly developed by IRSN (France) and GRS, Germany), have shown the influence of steam environment on core heat-up followed by material relocation, hydrogen production, vessel failure and aerosol generation along with release to containment. Hydro-accumulator injection for studied transients also gives rise to a steam-rich environment enhancing the material oxidation depending on the injection time and period. The generated information along with PSA-Level 2 is helpful to decide Plant Damage State (PDS) and fruitfully develop accident management strategies for the plant. 相似文献
73.
Shiqiang Hui Justin RollerSing Yick Xinge ZhangCyrille Decès-Petit Yongsong XieRadenka Maric Dave Ghosh 《Journal of power sources》2007
The advantages of lowering the operation temperature of SOFCs have attracted great interest worldwide. One of the major barriers to decreasing the operation temperature is the ohmic loss of the electrolyte. Maximizing the electrolyte ionic conductivity is of significant importance, especially in the absence of new electrolyte materials. The ionic conductivity of electrolytes can be influenced by many parameters. There has been an enormous effort in the literature for the improvement of the electrolyte ionic conductivity. From a practical point of view, this paper reviews various approaches to enhancing the ionic conductivity of polycrystalline zirconia- and ceria-based oxide electrolytes in the light of composition, microstructure, and processing. Suggestions are given for future work. 相似文献
74.
Microbial fuel cells are capable of producing electricity through the treatment of wastewater, however, the low power density poses main hurdles towards their wide application. In present work, microbial fuel cell based on multiple anodes, acting as baffle is constructed for achieving higher performance which can be scaled up for real life application. It is investigated for continuous sixty two days using distillery wastewater (WW) in three batches under ambient condition. During first batch, the WW is maintained under stagnant condition inside the anode chamber where as in the rest of the two batches WW is recirculated in the chamber. A maximum power density 427 mW m−2, is achieved under stagnant condition which is further enhanced to 597 mW m−2 under recirculation mode. Recirculation of WW reduces the internal resistance arising from the mass transfer by 50%. Maximum COD removal and Coulombic efficiency obtained is 43% and 23%. Biofouling on the surface of the membrane facing anode chamber is observed. 相似文献
75.
Souvik Biswas Ayan Roynaskar Chetan Kumar Hirwani Subrata Kumar Panda 《国际能源研究杂志》2018,42(12):3977-3986
The current article discussed the detail design and development of an experimental test rig to derive usable energy by utilizing the waste heat energy through a heat exchanger made of Bi2Te3 material. The accuracy including the efficiency of the fabricated device is demonstrated further by verifying the associated parameter through a simulation model (commercial finite element package, ANSYS 15.0). To imitate the waste hot air from the industry is achieved via a heat gun and fed to the test rig for the generation of thermoelectric power. The simulation model accuracy has been demonstrated by juxtaposing the associated experimental data and computational readings. Subsequently, the feasibility and optimum range of design parameters are established by comparing the experimental and the simulation data (triggered temperature difference, voltage output, and heat flux) generated at the interface of the thermoelectric power generators. In addition, the coefficient of determination (R2) value has been evaluated statistically and verified with the current experimental results for the demonstration of the relevancy. The statistical study shows the existence of the correlation between the current experimental and the simulation model. Also, the experimental result indicates the possible implementation of the newly developed system for the recovery from the waste heat either the automobile exhaust or any other kind of dissipated heat from the industries. 相似文献
76.
77.
Subinoy Mondal Smaranya Haque Debajyoti Kundu Deblina Dutta Apurba Ratan Ghosh 《Lakes & Reservoirs: Research and Management》2018,23(3):261-270
This study focused on isolation and identification of possible phosphate‐solubilizing bacteria (PSB ) from the sewage‐fed East Kolkata Wetland (EKWL ), a prospective water resource for pisciculture. In addition, different limnological parameters have been correlated with orthophosphate and seasonal variations. PSB have been isolated in Pikovskaya medium and identified morphologically and biochemically and finally analysed by 16S rDNA gene sequence. Limnological studies involving temperature (potentiometric), pH (potentiometric), dissolved oxygen (iodometric), ammonia‐nitrogen (spectrophotometric) and orthophosphate (spectrophotometric) concentrations were conducted. The results of this study established the presence of Bacillus megaterium , a potential PSB in EKWL . The activity of B. megaterium is also supported by the seasonal orthophosphate variations. The changes in concentration of other limnological parameters were also prominent. The water quality parameters of temperature (r = 0.886), dissolved oxygen (r = 0.729) and ammonia‐nitrogen (r = 0.396) concentrations exhibited a positive correlation with orthophosphate and a negative correlation with pH (r = ?0.699). The B. megaterium obtained in this study, exhibited a significant alteration in regard to orthophosphate content and relationships with other factors. Further experiment on the soluble phosphorus solubilization potential of B. megaterium revealed the biological availability of phosphorus was increased by threefold after 120 hr of incubation, with the decreasing pH value, although the phytase activity was 0.419 U/ml. PSB have a vital function in plant nutrition in supplying phosphate, essential nutrients and its uptake results in appropriate functioning and metabolism of different aquatic plants and organisms. PSB are competent biofertilizer to amplify aquaculture production for sustainable development. 相似文献
78.
Software and Systems Modeling - Models can be used to ease and manage the development, evolution, and runtime adaptation of a software system. When models are adapted, the resulting models must be... 相似文献
79.
Smarajit Ghosh 《国际能源研究杂志》2020,44(3):2355-2367
Sustainable power sources, that is, the energy produced as of hydro control, biomass, wind, geothermal, sunlight, and sea resources deliberated as innovative choice intended to create clean energy and crisp water. The majority of the nations have challenged issues proceeding freshwater and power creation, which tends to the utilization of sustainable power source-controlled desalination frameworks. In this work expanding the clean water accessibility that satisfies the load need, Hybrid Renewable Energy Systems (HRES) on the basis of Reverse Osmosis Desalination (ROD) is structured and then displayed. HRES is getting to be well known for power applications because of advances in sustainable power sources. Here, an innovative calculation based on Social Spider Optimization (SSO) is aimed at explaining the required optimization tasks. The technique referenced is turned out to be powerful, utilizing sustainable power source framework. The proposed system is contrasted with a genuine contextual analysis in the eastern part of Iran, Canary Islands and outcomes demonstrate that it has been successfully utilized thinking about both power quality and cost. Also, the outcomes acquired by the suggested technique are very encouraging to outline the capability and strength of the introduced methodology. 相似文献
80.