全文获取类型
收费全文 | 913篇 |
免费 | 28篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 160篇 |
金属工艺 | 35篇 |
机械仪表 | 15篇 |
建筑科学 | 20篇 |
矿业工程 | 2篇 |
能源动力 | 54篇 |
轻工业 | 41篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 120篇 |
一般工业技术 | 232篇 |
冶金工业 | 90篇 |
原子能技术 | 35篇 |
自动化技术 | 131篇 |
出版年
2023年 | 8篇 |
2022年 | 24篇 |
2021年 | 41篇 |
2020年 | 40篇 |
2019年 | 35篇 |
2018年 | 48篇 |
2017年 | 36篇 |
2016年 | 24篇 |
2015年 | 22篇 |
2014年 | 30篇 |
2013年 | 51篇 |
2012年 | 38篇 |
2011年 | 43篇 |
2010年 | 28篇 |
2009年 | 36篇 |
2008年 | 31篇 |
2007年 | 33篇 |
2006年 | 20篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 11篇 |
2002年 | 16篇 |
2001年 | 16篇 |
2000年 | 14篇 |
1999年 | 12篇 |
1998年 | 23篇 |
1997年 | 15篇 |
1996年 | 21篇 |
1995年 | 17篇 |
1994年 | 15篇 |
1993年 | 22篇 |
1992年 | 11篇 |
1991年 | 17篇 |
1990年 | 16篇 |
1989年 | 14篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有946条查询结果,搜索用时 31 毫秒
11.
Heavy metals in maternal and cord blood 总被引:8,自引:0,他引:8
Raghunath R Tripathi RM Sastry VN Krishnamoorthy TM 《The Science of the total environment》2000,250(1-3):135-141
Heavy metal concentrations have been determined in maternal and cord blood samples collected from mothers in the age group 20-25 years with full-term neonates (37-40 weeks). The concentrations of Pb, Cd, Cu and Zn were found to be low in cord blood as compared to mother's blood and the ratio between cord blood and maternal blood for the respective elements was found to be approximately 0.80, 0.86, 0.47 and 0.40. On the other hand, the concentrations of Fe and Mg in the mother's blood were found to be lower than those in the cord blood. Prenatal exposure to lead in Mumbai, though low (5.1 microg/dl), is approximately 2-3 times higher than that observed in Canada or Italy. A strong correlation (r = 0.79) between the maternal and cord blood lead levels has been observed during the present study. 相似文献
12.
Tripathi RM Raghunath R Kumar AV Sastry VN Sadasivan S 《The Science of the total environment》2001,267(1-3):101-108
Average concentration of Pb in atmospheric air particulates in different suburbs of Mumbai was studied for almost a decade and its spatial and temporal profiles are discussed in relation to emission sources. In general the concentration of Pb in all the residential suburban atmosphere is well below the Central Pollution Control Board (CPCB, 1994) prescribed limit of 1.5 microg m(-3) barring a few exceptions for some residential/industrial sites, such as those of Thane and Kurla scrap yards. The correlation between blood lead of children and air lead reveals that the blood Pb level in children could increase by 3.6 microg dl(-1) for an incremental rise of 1.0 microg Pb m(-3) of air. The temporal profile of air Pb values indicates a decreasing trend in residential suburbs (Khar: 1984, 0.39 microg m(-3); 1996, 0.17 microg m(-3)) as well as in suburban residential areas with low traffic (Goregaon: 1984, 0.53 microg m(-3); 1996, 0.30 microg m(-3)). 相似文献
13.
In this paper, we propose a double aperture double-gate AlGaN/GaN vertical high-electron-mobility transistor (HEMT) to improve the device characteristics, such as the current and the ON resistance (\(\hbox {\textit{R}}_{\mathrm{ON}}\)). The proposed vertical HEMT results are compared to the conventional single aperture single-gate vertical HEMT of equal dimensions, and increased drain current and lower \(\hbox {\textit{R}}_{\mathrm{ON}}\) are shown. A comprehensive simulation study has also been carried out for the proposed device, to analyse the impact of thickness and doping concentration of aperture, drift region, and current blocking layer. In addition, the effect of different materials in current blocking layer on device characteristics is also studied. The obtained results and their effect on device characteristics have been thoroughly analysed and explained accordingly. 相似文献
14.
Thin films of CdSe and silver(Ag)-doped CdSe have been prepared on glass substrates by thermal evaporation in argon gas atmosphere. X-ray diffraction pattern indicates the presence of hexagonal structure with preferred orientation along (100) plane. Elemental composition of the thin films has been analyzed using energy dispersive X-ray analysis. Scanning electron microscopy has been used to investigate the morphology of the thin films. Transmission electron microscope reveals spherical nature of nanoparticles. A decrease in the band gap due to the formation of band tails in the band gap with increase in Ag doping in CdSe lattice has been observed. Photoluminescence spectra indicate redshift in band edge emission peak with increase in Ag doping in CdSe. Electrical conductivity measurements are also studied, and two types of conduction mechanisms taking part in the transport phenomena are observed. Hall measurements indicate n-type behavior of undoped and Ag-doped CdSe thin films. 相似文献
15.
Effect of Alumina Reactivity on the Densification and Properties of Al2O3–Cr2O3 Refractories 下载免费PDF全文
Mithun Nath Vakiti Pradeep Reddy Somnath Sinhamahapatra Kausik Dana Arup Ghosh Himansu Sekhar Tripathi 《International Journal of Applied Ceramic Technology》2015,12(3):608-613
Alumina‐chrome (Al2O3–Cr2O3) refractories with Al2O3:Cr2O3 molar ratio 1:1 were synthesized in the temperature range of 1400–1700°C by conventional solid–oxide reaction route. The effect of different aluminas (viz., hydrated and calcined) on the densification, microstructure, and properties of Al2O3–Cr2O3 refractories was investigated without changing the Cr2O3 source. The starting materials were analyzed to determine the chemical composition, mineralogy, density, surface area, and particle size. Sintered materials were characterized in terms of densification, phase assemblage, and mechanical strength at room temperature and at higher temperatures. Microstructural evolution at different sintering temperature was correlated with sintering characteristics. It can be concluded that the Al2O3–Cr2O3 refractories prepared with hydrated alumina as Al2O3 source show better densification and hot mechanical strength than corresponding calcined variety. 相似文献
16.
17.
Pavan Gangwar Rajiv Singh Ravi Pratap Tripathi Ashutosh Kumar Singh 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2019,41(15):1828-1837
Solar irradiance being considered as one of the most important alternative sources of energy can be harnessed in the form of electrical power using photovoltaic panels erected under the sun. Optimum conversion of power from solar panels can be obtained by using Maximum Power Point Tracking (MPPT), which involves continuously adjusting the angle of panels according to the change in the angle of falling irradiance. These trackers, however, use some amount of power for operation of MPPT equipment. Various techniques for arranging the solar panels in three dimensions have been suggested for optimizing the output power from them. The inspiration behind arranging the panels are often drawn from the natural trees where the branches and the leaves follow a particular pattern called phyllotaxy which is directly analogous to the Fibonacci number and Golden ratio. In this research work, the power output from two solar tree models based on 3/8 and 2/5 phyllotaxy pattern and solar conventional panel compared under similar irradiance conditions. There are so many phyllotaxy patterns like 1/3, 2/5, 3/8, etc. When the solar panels aligned in different phyllotaxies, then the orientation direction of solar panels are distinct. Each solar panel connected in solar trees is in a different direction, so that they received the maximum amount of sunlight throughout the day as compared to conventional panels which is oriented unidirectional. 相似文献
18.
Semiconductors - The quest for downscaling of devices has led to novel configurations with better performance parameters of which Junction Less (JL) MOSFET is an important configuration regarding... 相似文献
19.
The Indian test blanket module(TBM) program in ITER is one of the major steps in the Indian fusion reactor program for carrying out the RD activities in the critical areas like design of tritium breeding blankets relevant to future Indian fusion devices(ITER relevant and DEMO).The Indian Lead–Lithium Cooled Ceramic Breeder(LLCB) blanket concept is one of the Indian DEMO relevant TBM,to be tested in ITER as a part of the TBM program.Helium-Cooled Ceramic Breeder(HCCB) is an alternative blanket concept that consists of lithium titanate(Li_2TiO_3) as ceramic breeder(CB) material in the form of packed pebble beds and beryllium as the neutron multiplier.Specifically,attentions are given to the optimization of first wall coolant channel design and size of breeder unit module considering coolant pressure and thermal loads for the proposed Indian HCCB blanket based on ITER relevant TBM and loading conditions.These analyses will help proceeding further in designing blankets for loads relevant to the future fusion device. 相似文献
20.
Dr. Richa Sharma Tulika Srivastava Alka Raj Pandey Dr. Tripti Mishra Dr. Bhagyashri Gupta Dr. Sabbu Sathish Reddy Dr. Suriya P. Singh Dr. Tadigoppula Narender Aradhya Tripathi Dr. Balasubramanian Chandramouli Dr. Koneni V. Sashidhara Dr. Smriti Priya Dr. Niti Kumar 《ChemMedChem》2021,16(13):2146-2156
Defective protein folding and accumulation of misfolded proteins is associated with neurodegenerative, cardiovascular, secretory, and metabolic disorders. Efforts are being made to identify small-molecule modulators or structural-correctors for conformationally destabilized proteins implicated in various protein aggregation diseases. Using a metastable-reporter-based primary screen, we evaluated pharmacological chaperone activity of a diverse class of natural products. We found that a flavonoid glycoside ( C-10 , chrysoeriol-7-O-β-D-glucopyranoside) stabilizes metastable proteins, prevents its aggregation, and remodels the oligomers into protease-sensitive species. Data was corroborated with additional secondary screen with disease-specific pathogenic protein. In vitro and cell-based experiments showed that C-10 inhibits α-synuclein aggregation which is implicated in synucleinopathies-related neurodegeneration. C-10 interferes in its structural transition into β-sheeted fibrils and mitigates α-synuclein aggregation-associated cytotoxic effects. Computational modeling suggests that C-10 binds to unique sites in α-synuclein which may interfere in its aggregation amplification. These findings open an avenue for comprehensive SAR development for flavonoid glycosides as pharmacological chaperones for metastable and aggregation-prone proteins implicated in protein conformational diseases. 相似文献