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Bulk material of (Se80Te20)100 xAgx (0rxr4) system was prepared by using a conventional
melt quenching technique. Thin films of a-(Se80Te20)100 xAgx (0rxr4) were deposited by the
vacuum evaporation technique at a base pressure of 10 4 mbar onto well-cleaned glass substrates.
Temperature dependence of electrical conductivity in the temperature range of 263–333 K has been
studied. There is increase in the value of conductivity with increase in temperature as well as with
Ag content. The measurements of intensity dependence of photoconductivity show that the photoconductivity
increases with intensity as a power law where the power is found to be between 0.5 and
1.0, representing the continuous distribution of traps. Rise and decay of photocurrent with time at
room temperature at different light intensities for (Se80Te20)98Ag2 thin film samples have also been
reported. The results have been explained on the basis of the Dember voltage and interaction between
photoexcited holes and the trapped electrons on the surface. 相似文献
105.
Mineralogy and carbothermal reduction behaviour of vanadium-bearing titaniferous magnetite ore in Eastern India 下载免费PDF全文
Saikat Samanta Manik Chandra Goswami Tapan Kumar Baidya Siddhartha Mukherjee Rajib Dey 《矿物冶金与材料学报》2013,20(10):917-924
Vanadium-bearing titaniferous magnetite bands hosted by Precambrian gabbro-norite-anorthositic rocks or their metamorphic equivalents were discovered in some parts of Eastern Indian Shield, containing 48%–49% Fe (total), 10%–25% TiO2, and 0.3%–2.20% V2O5 by mass. Mineralogical and petrological study, composition, and characterization of the vanadium-bearing titaniferous magnetite ore were carried out by scanning electron microscopy-energy dispersive X-ray (SEM-EDX), wave length X-ray florescence (WDXRF), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), etc. Chemical beneficiation for valuable metals, such as Fe, Ti, and V, was performed by reduction roasting. The direct and indirect reduction were investigated by mixing the lump ore with solid activated charcoal in a closed reactor and purging the reducing gas mixture in standard reducibility index apparatus at different temperatures and time intervals. The reduction roasting parameters were optimized. Finally, the reduced samples were crushed and upgraded by magnetic separation. The results show that, the maximum mass fractions of magnetic and nonmagnetic parts achieved are 69.36% and 30.64%, respectively, which contain 10.6% TiO2 and 0.84% V2O5 in the magnetic part and 36.5% TiO2 and 0.22% V2O5 in the nonmagnetic part. 相似文献
106.
Numerical investigation of the effect of transitory strand opening on mixing in a multistrand tundish 下载免费PDF全文
Sabin Kumar Mishra Pradeep Kumar Jha Satish Chandra Sharma Satish Kumar Ajmani 《矿物冶金与材料学报》2011,18(5):535-542
In a multistrand, the outlet near the inlet produces short circuiting flow. This leads to the formation of dead zones inside the tundish, and consequently, the mean residence time decreases. In the present study, numerical investigation of mixing inside a delta shaped tundish with sloping boundaries was carried out by solving the Navier-Stokes equation and employing the standard turbulence model. To decrease the dead zone volume inside the tundish, the effect of closing the outlet near the inlet for a small amount of time and further opening it on the mixing behavior of the tundish was studied. The outlets near the inlet were closed for varying amount of time, and the transient analysis of fluid flow and the tracer dispersion study were carried out to find the mixing parameters of the tundish, namely, mean residence time and the ratio of mixed to dead volume of the tundish. An optimum closure time of the near outlet has been found, which yields best mixing inside the tundish. The numerical code was validated against the experimental observation by performing the tracer dispersion study inside a multistrand tundish and the reasonably good match between the experimental and numerical results in terms of residence time distribution (RTD) curves. The results obtained from the present study confirm the strong role of choosing the right time for opening and closing the outlets to get improved characteristics for the fluid flow and mixing behavior of the tundish. The educational version of computational fluid dynamics (CFD) software PHOENICS was used to solve the governing equations and interpret the results in different forms. 相似文献
107.
Human oestrogen receptor cDNA: sequence, expression and homology to v-erb-A 总被引:182,自引:0,他引:182
We have cloned and sequenced the complete complementary DNA of the oestrogen receptor (ER) present in the breast cancer cell line MCF-7. The expression of the ER cDNA in HeLa cells produces a protein that has the same relative molecular mass and binds oestradiol with the same affinity as the MCF-7 ER. There is extensive homology between the ER and the erb-A protein of the oncogenic avian erythroblastosis virus. 相似文献
108.
Performance evaluation for selectivity of the flocculant on hematite in selective flocculation 下载免费PDF全文
Lopamudra Panda Pradip K. Banerjee Surendra Kumar Biswal R. Venugopal N. R. Mandre 《矿物冶金与材料学报》2013,20(12):1123-1129
Increased demand for iron ore necessitates the utilization of low-grade iron ore fines, slimes, and existing tailings. Selective flocculation can be an alternative physico-chemical process for utilizing these low-grade fines, slimes, and tailings. In selective flocculation, the most critical objective is the selection of proper reagents that will make floc of desired minerals. In present study, selective flocculation was applied to ultra-fine synthetic mixtures of hematite and kaolinite, and the Fe value was upgraded up to 65.78% with the reduction of Al2O3 and SiO2 values to 2.65% and 3.66%, respectively. Here, degraded wheat starch was used as a flocculant.In this process, separation occurs on the basis of the selectivity of the flocculant. The selectivity of the flocculant can be quantified in terms of separation efficiency. Here, an attempt was also made to develop a correlation between separation efficiency and major operating parameters such as flocculent dose, pH value, and solid concentration to predict the separation performance. 相似文献
109.
Microstructure studies of air-plasma-spray-deposited CoNiCrAlY coatings before and after thermal cyclic loading for high-temperature application 下载免费PDF全文
In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying (APS) techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and atomic force microscopy (AFM) were used to investigate the phases and microstructure of the as-sprayed, APS-deposited CoNiCrAlY bond-coatings. The aim of this work was to study the suitability of the bond-coat materials for high temperature applications. Confirmation of nanoscale grains of the γ/γ′-phase was obtained by TEM, high-resolution TEM, and AFM. We concluded that these changes result from the plastic deformation of the bond-coat during the deposition, resulting in CoNiCrAlY bond-coatings with excellent thermal cyclic resistance suitable for use in high-temperature applications. Cyclic oxidative stability was observed to also depend on the underlying metallic alloy substrate. 相似文献
110.
中国公路沥青路面水损害气候影响分区方案 总被引:4,自引:0,他引:4
为了了解中国气候条件对沥青路面水损害的影响情况,对沥青路面水损害研究成果进行了回顾与分析,认为影响沥青路面水损害的主要气候因素为:降水、高温以及冻融循环过程.降水与高温过程组合以及降水与冻融循环过程组合是影响沥青路面水损害的两个主要气候过程.针对这两个主要气候过程,构建了降水气温指数和降水冰冻指数,用于评价上述气候过程对沥青路面水损害的影响.分析结果表明:利用降水气温指数和降水冰冻指数划分中国公路沥青路面水损害气候影响分区是合理可行的;根据各个气候指数的工程意义和等概率原则,确定了分区界限,拟定了包含14个区的分区方案. 相似文献