全文获取类型
收费全文 | 842篇 |
免费 | 51篇 |
国内免费 | 1篇 |
专业分类
化学 | 468篇 |
晶体学 | 8篇 |
力学 | 10篇 |
数学 | 45篇 |
物理学 | 219篇 |
无线电 | 144篇 |
出版年
2023年 | 11篇 |
2022年 | 14篇 |
2021年 | 18篇 |
2020年 | 31篇 |
2019年 | 22篇 |
2018年 | 23篇 |
2017年 | 6篇 |
2016年 | 36篇 |
2015年 | 21篇 |
2014年 | 31篇 |
2013年 | 49篇 |
2012年 | 47篇 |
2011年 | 51篇 |
2010年 | 26篇 |
2009年 | 26篇 |
2008年 | 35篇 |
2007年 | 39篇 |
2006年 | 33篇 |
2005年 | 34篇 |
2004年 | 23篇 |
2003年 | 35篇 |
2002年 | 21篇 |
2001年 | 11篇 |
2000年 | 15篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 14篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1970年 | 4篇 |
排序方式: 共有894条查询结果,搜索用时 15 毫秒
71.
Anita Topkar S. Praveenkumar Bharti Aggarwal S. K. Kataria M. D. Ghodgaonkar 《Pramana》2007,69(6):1085-1088
A specific research and development program has been carried out by BARC in India to develop the technology for large area
silicon strip detectors for application in nuclear and high energy physics experiments. These strip detectors will be used
as pre-shower detector in the CMS experiment at LHC, CERN for π
0/λ rejection. The fabrication technology to produce silicon strip detectors with very good uniformity over a large area of ∼40
cm2, low leakage currents of the order of 10 nA/cm2 per strip and high breakdown voltage of >500 V has been developed by BARC. The production of detectors is already under way
to deliver 1000 detector modules for the CMS and 90% production is completed. In this paper, research and development work
carried out to develop the detector fabrication technology is briefly described. The performance of the silicon strip detectors
produced in India is presented. The present status of the detector technology is discussed.
相似文献
72.
Ravi Aggarwal Durairaj Baskaran 《Journal of polymer science. Part A, Polymer chemistry》2011,49(23):5049-5056
Hydrated sodium montmorillonite (Na‐clay) has been used as a catalyst support for the heterogeneous atom transfer radical polymerization of benzyl methacrylate in the presence of various concentrations of water, reducing agent, and CuBr2 in anisole at ambient temperature. The polymerization was promoted via reduction of CuII to CuI through the addition of sodium ascorbate (NaAsc) as a reducing agent in aqueous solution. The polymerizaton proceeded in a controlled manner and produced poly(benzyl methacylate) with moderately narrow molecular weight distribution (MWD) when performed under optimum conditions of hydration (10 wt % ≤ H2O/Na‐clay ≤ 21 wt %) and reducing agent (0.15 ≤ [NaAsc]/[I] ≤ 0.23). The polymerization was uncontrolled if hydration and NaAsc exceed above their optimum range of concentrations. Apparent rate of the polymerization (kapp) increased in the presence of decane–anisole (1/3, v/v) mixture solvent. Selective adsorption of decane at the interfaces of the hydrated clay was attributed for the rate enhancement due to increased polymer and hydrophobic interface interaction. The polymerization progressed in a controlled manner as confirmed by the first‐order time‐conversion plot, linear increase in molecular weights, and moderately narrow MWDs over conversion. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
73.
74.
75.
76.
Heavy metal fluoride (HMF) glass optical fibres were spliced by fusing the two ends of fibres using a DC arc. An average optical loss of 0.08 dB per splice and strengths of up to 600 MPa were achieved for fusion splices using an inert gas purge during splicing. Estimates are made to determine the feasibility of achieving a splice loss of 0.005 dB for single-mode (HMF) fibres.<> 相似文献
77.
We have performed numerical analysis of the one-dimensional dynamics of the cylindrical/spherical dust ion acoustic shock waves in unmagnetized dusty plasma consisting of positive ions, immobile dust particles, and nonextensive distributed cold and hot electrons. A multiple-scale expansion method is used to derive Burgers Equation (BE) and modified Burgers equation (MBE) by including higher order nonlinearity. The basic characteristics of the shock waves have been analysed numerically and graphically for different physical parameters relevant to Saturn' E ring through 2D figures. The parametric dependence of dust ion acoustic shock waves on some plasma parameters nonextensive index, density, and temperature of cold and hot electrons, concentration of dust particles, thermal effects and kinematic viscosity of ions is explored. Furthermore, it is found that the nonplanar geometry effects have an important impact on the establishment of shock waves. The amplitude of the wave decreases faster as one departs away from the axis of the cylinder or centre of the sphere. Such decaying behaviour continues as time progresses. It is also found that an increasing dust concentration decreases the amplitude of the dust ion acoustic shock waves. 相似文献
78.
A quantitative and fast method of dissolution of refractory thoria (ThO2) was developed for the determination of thorium (Th) in a given sample. The dissolution of sintered ThO2 powder, microspheres and pellets using 88% phosphoric acid was investigated. The conditions of quantitative dissolution of ThO2 microspheres were optimized by conventional heating in autoclave and also by microwave heating. 100 mg of sintered ThO2 microspheres were dissolved in 8 g of phosphoric acid in an autoclave, and heating at 170 °C for 3 h, in comparison to 5 g of phosphoric acid by microwave heating (375 W) at 220 °C for 1 h. Dissolution studies on the powder form of sintered ThO2 were also performed. 1 g of sintered ThO2 powder could be dissolved in 6.5 g of phosphoric acid in autoclave heating at 170 °C for 1 h. Strong complexing of (PO4)3− with Th4+ may be the influencing factor for quantitative dissolution of ThO2. 相似文献
79.
V. V. Vinogradov A. V. Agafonov A. V. Vinogradov K. T. Pillai Rajesh V. Pai S. K. Mukerjee S. K. Aggarwal 《Journal of Sol-Gel Science and Technology》2011,60(1):6-10
Mesoporous γ-Al2O3 materials with high surface area and a narrow pore size distribution were synthesized by facile sol–gel procedure with application
of the polymer–colloid complex as a template. 相似文献