全文获取类型
收费全文 | 712篇 |
免费 | 20篇 |
国内免费 | 2篇 |
专业分类
化学 | 469篇 |
晶体学 | 5篇 |
力学 | 11篇 |
数学 | 31篇 |
物理学 | 218篇 |
出版年
2024年 | 5篇 |
2023年 | 7篇 |
2022年 | 21篇 |
2021年 | 17篇 |
2020年 | 21篇 |
2019年 | 21篇 |
2018年 | 16篇 |
2017年 | 23篇 |
2016年 | 27篇 |
2015年 | 12篇 |
2014年 | 18篇 |
2013年 | 57篇 |
2012年 | 25篇 |
2011年 | 32篇 |
2010年 | 26篇 |
2009年 | 26篇 |
2008年 | 26篇 |
2007年 | 28篇 |
2006年 | 35篇 |
2005年 | 25篇 |
2004年 | 20篇 |
2003年 | 12篇 |
2002年 | 21篇 |
2001年 | 17篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1991年 | 5篇 |
1989年 | 10篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1973年 | 9篇 |
1963年 | 3篇 |
排序方式: 共有734条查询结果,搜索用时 62 毫秒
121.
Kamath Srinivas S. Narayana B. D’Souza Renita Shiny Nayak S. Rashmi Mohan M. P. Dileep B. N. Baburajan A. Ravi P. M. Karunakara N. 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(2):389-397
Tritium concentration was monitored in different water sources collected around Kaiga Nuclear Power plant, India. The concentration was in the ranges?<?1.9–27.4 Bq L?1 (GM?=?4.0 Bq L?1) for groundwater,?<?1.9–42.1 Bq L?1 (GM?=?3.5 Bq L?1) for surface water and in 12.4–42.0 Bq L?1 (GM?=?24.07 Bq L?1) for reservoir water. The concentration values observed in this study are similar to those reported for other PHWR stations of the world. The radiation dose to the public due to ingestion of Tritium through groundwater was computed to be 0.08 μSvy?1.
相似文献122.
Rikarani R. Choudhury Smita Mohanty Sanjay Kumar Nayak 《International Journal of Polymer Analysis and Characterization》2019,24(4):334-345
This paper first time reports the preparation of random anionic copolymers from vinyl acetate (VAc) bearing electro-donating substituent and sodium 4-vinylbenzenesulfonate (SSA) having electro-withdrawing substituent. Copolymers (PVA-co-SSA) of different composition have been successfully prepared by a simple free radical solution polymerization technique. Resulting final copolymer contained neutral hydrophilic as well as ionizable ion exchange sites. Evaluation of spectral data obtained from Fourier transform Infrared spectroscopy, Raman spectroscopy, and 1H Nuclear magnetic resonance helped in identifying and confirming the chemical structure of copolymers. Characterization of copolymers by gel permeation chromatography revealed high molecular weight with moderate polydispersity index. Analysis of thermal stability and glass transition temperature of copolymers by thermogravimetric analysis and differential scanning calorimetry were found in between corresponding homopolymers. Physicochemical properties of PVA-co-SSA can be beneficial for prospective advanced application in the niche area of smart membrane technology for energy and environment. 相似文献
123.
We develop the density-matrix renormalization group (DMRG) technique for numerically studying incompressible fractional quantum Hall (FQH) states on the sphere. We calculate accurate estimates for ground-state energies and excitation gaps at FQH filling fractions nu=1/3 and nu=5/2 for systems that are considerably larger than the largest ever studied by exact diagonalization. We establish, by carefully comparing with existing numerical results on smaller systems, that DMRG is a highly effective numerical tool for studying incompressible FQH states. 相似文献
124.
We consider quantum Hall states at even-denominator filling fractions, especially nu=5/2, in the limit of small Zeeman energy. Assuming that a paired quantum Hall state forms, we study spin ordering and its interplay with pairing. We give numerical evidence that at nu=5/2 an incompressible ground state will exhibit spontaneous ferromagnetism. The Ginzburg-Landau (GL) theory for the spin degrees of freedom of paired Hall states is a perturbed CP2 model. We compute the coefficients in the GL theory by a BCS Stoner mean-field theory for coexisting order parameters, and show that even if repulsion is smaller than that required for a Stoner instability, ferromagnetic fluctuations can induce a partially or fully polarized superconducting state. 相似文献
125.
A class of topological excitations-the odd-winding number vortices-in a spinless 2D chiral p-wave (px+ipy) superconductor traps Majorana fermion states in the vortex cores. For a dilute gas of such vortices, the lowest energy fermionic eigenstates are intrinsically nonlocal. We predict two testable signatures of this unusual quantum nonlocality in quasiparticle tunneling experiments. We discuss why the associated teleportationlike phenomenon does not imply the violation of causality. 相似文献
126.
Nayak Debasis Dora J. K. Ghosh Sudipto Adyam Venimadhav 《Journal of Solid State Electrochemistry》2022,26(5):1231-1239
Journal of Solid State Electrochemistry - Sodium-ion batteries have emerged as an exciting alternative to commercially dominant lithium-ion batteries for electric vehicles and other applications.... 相似文献
127.
Mithilesh Kumar Nayak Jessica Stubbe Dr. Nicolás I. Neuman Dr. Ramakirushnan Suriya Narayanan Sandipan Maji Prof. Dr. Carola Schulzke Prof. Vadapalli Chandrasekhar Prof. Dr. Biprajit Sarkar Dr. Anukul Jana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4425-4431
This work presents a stepwise reversible two-electron transfer induced hydrogen shift leading to the conversion of a bis-pyrrolinium cation to an E-diaminoalkene and vice versa. Remarkably, the forward and the reverse reaction, which are both reversible, follow two completely different reaction pathways. Establishing such unprecedented property in this type of processes was possible by developing a novel synthetic route towards the starting dication. All intermediates involved in both the forward and the backward reactions were comprehensively characterized by a combination of spectroscopic, crystallographic, electrochemical, spectroelectrochemical, and theoretical methods. The presented synthetic route opens up new possibilities for the generation of multi-pyrrolinium cation scaffold-based organic redox systems, which constitute decidedly sought-after molecules in contemporary chemistry. 相似文献
128.
Natural convection in an internally heated porous bed of height and diameter of 450 mm and 500 mm, respectively, and superposed with the fluid layer has been experimentally investigated. The onset of natural convection in the bed is indicated by change in the rate of temperature rise within the bed. An empirical model based on local Nusselt number and local Rayleigh number has been developed. A comparison of the present model with the models in literature is made to draw out the differences between the local heat transfer of large multidimensional beds and the average heat transfer of small beds. 相似文献
129.
130.
Priyabrata Pattanaik Sabita Nayak Deepak Ranjan Mishra Pravati Panda Bishnu Prasad Raiguru Nilima Priyadarsini Mishra Seetaram Mohapatra N. Arjunreddy Mallampudi Chandra Shekhar Purohit 《Tetrahedron letters》2018,59(27):2688-2694
A competent and highly discriminating one-pot synthesis of highly diversified novel functionalized indenoquinoxalone grafted spiropyrrolidine linked chromene-3-carbonitrile conjugates accumulating three pharmocophoric cores, heterocyclic indenoquinoxalone, pyrrolidines and chromene-3-carbonitrile in a single molecular framework by means of 1,3-dipolar cycloaddition reaction between indenoquinoxalone, proline/benzyl amine and chromene-3-carbonitrile in ethanol under classical and microwave conditions is described. The three component 1,3-dipolar cycloaddition reaction proceeds via in situ generation of azomethine ylides by the decarboxylative condensation of indenoquinoxalone with proline/benzyl amine and their selectivity towards the endo cyclic double bonds of dipolarophile (chromene-3-carbonitrile) leading to the formation of highly functionalised regio- and diastereoselective molecular hybrids. This methodology exemplifies the green chemistry protocol such as mild reaction conditions, high yields, one-pot procedure and operational simplicity. 相似文献