全文获取类型
收费全文 | 1008篇 |
免费 | 78篇 |
国内免费 | 30篇 |
专业分类
化学 | 320篇 |
晶体学 | 2篇 |
力学 | 80篇 |
综合类 | 75篇 |
数学 | 205篇 |
物理学 | 434篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 38篇 |
2021年 | 32篇 |
2020年 | 26篇 |
2019年 | 27篇 |
2018年 | 28篇 |
2017年 | 66篇 |
2016年 | 62篇 |
2015年 | 57篇 |
2014年 | 61篇 |
2013年 | 82篇 |
2012年 | 46篇 |
2011年 | 48篇 |
2010年 | 42篇 |
2009年 | 43篇 |
2008年 | 39篇 |
2007年 | 54篇 |
2006年 | 31篇 |
2005年 | 39篇 |
2004年 | 48篇 |
2003年 | 35篇 |
2002年 | 27篇 |
2001年 | 23篇 |
2000年 | 19篇 |
1999年 | 23篇 |
1998年 | 15篇 |
1997年 | 16篇 |
1996年 | 16篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有1116条查询结果,搜索用时 421 毫秒
71.
B. N. Chetverushkin E. V. Shilnikov 《Computational Mathematics and Mathematical Physics》2008,48(2):295-305
A parallel software package designed for the numerical simulation of three-dimensional viscous gas flows is presented. The numerical algorithm is based on kinetically consistent difference schemes used on locally refined grids. The software package has been tested in various super-and subsonic flow problems. It provides an opportunity for the direct simulation of turbulent flows. The efficiency of parallelization is analyzed depending on the problem size and the number of processors. 相似文献
72.
73.
This paper describes recent experience in tackling large nonlinear integer programming problems using the MINOS large-scale optimization software. A technique is presented for extending the constrained search approach used in MINOS to exploring integer-feasible solutions once a continuous optimal solution is obtained. Computational experience with this approach is described for two classes of problems: quadratic assignment problems and pipeline network design problems. 相似文献
74.
Oliver G. Maupin Andrew D. Baczewski Peter J. Love Andrew J. Landahl 《Entropy (Basel, Switzerland)》2021,23(6)
We present example quantum chemistry programs written with JaqalPaq, a python meta-programming language used to code in Jaqal (Just Another Quantum Assembly Language). These JaqalPaq algorithms are intended to be run on the Quantum Scientific Computing Open User Testbed (QSCOUT) platform at Sandia National Laboratories. Our exemplars use the variational quantum eigensolver (VQE) quantum algorithm to compute the ground state energies of the , , and molecules. Since the exemplars focus on how to program in JaqalPaq, the calculations of the second-quantized Hamiltonians are performed with the PySCF python package, and the mappings of the fermions to qubits are obtained from the OpenFermion python package. Using the emulator functionality of JaqalPaq, we emulate how these exemplars would be executed on an error-free QSCOUT platform and compare the emulated computation of the bond-dissociation curves for these molecules with their exact forms within the relevant basis. 相似文献
75.
Tsuneomi Kawasaki 《Journal of fluorine chemistry》2010,131(4):525-1118
Amplification of enantiomeric enrichment is a key feature for the chemical evolution of biological homochirality from the origin of chirality. The aggregations of the enantiomers by diastereomeric interactions enable the modification of their enantiomeric excess during some chemical processes. Fluorine-containing chiral compounds possess large amplification effect via distillation, sublimation and achiral chromatography by self-disproportionation. Asymmetric amplifications in enantioselective catalysis occur by the differential formation and reactivity between homochiral and heterochiral aggregate in solution.We described the amplification of ee in asymmetric autocatalysis of 5-pyrimidyl alkanol in the reaction between diisopropylzinc and pyrimidine-5-carbaldehdye. During the reactions extremely low ee (ca. 0.00005% ee) can be amplified to achieve more than 99.5% ee. Since the proposed origins of chirality such as CPL, quartz, chiral organic crystals of achiral compounds and statistical fluctuation of ee can initiate the asymmetric autocatalysis with amplification of ee, the proposed origin of chirality can be linked with enantiopure organic compound in conjunction with amplification of ee by asymmetric autocatalysis. In addition, we described that the carbon isotopically chiral compound triggers the asymmetric autocatalysis of 5-pyrimiodyl alkanol to afford the enantioenriched product with the absolute configuration correlated with that of carbon isotope chirality, that is, isotope chirality including hydrogen isotopes can control the enantioselectivity of asymmetric addition of alkyl metal reagent to aldehyde. 相似文献
76.
Santos HM Glez-Peña D Reboiro-Jato M Fdez-Riverola F Diniz MS Lodeiro C Capelo-Martínez JL 《Electrophoresis》2010,31(20):3407-3419
In the present work we report on a novel and fast protocol for accurate bottom-up protein quantification that overcomes the drawbacks of in-gel digestion and MALDI analysis, while maintaining their benefits. It relies on the following steps: (i) gel electrophoresis separation of proteins, (ii) fast in-gel protein digestion with trypsin, (iii) (18)O-labeling through the decoupled method, (iv) quantification through selected peptides previously chosen using the (18)O inverse labeling approach and that, finally, (v) it takes advantage of software specifically developed to select the peptides that will drive the quantification of the protein in an automated mode. We have accurately quantified the following six proteins: glycogen phosphorylase, BSA, ovalbumin, carbonic anhydrase, trypsin inhibitor, and α-lactalbumin. As a case study we have quantified the protein vitellogenin in plasma of Cyprinus carpio exposed to high levels of estrogens. The proposed new protocol was validated against the traditional ELISA method; both were found to provide comparable results (non-parametric Mann-Whitney U-test). 相似文献
77.
介绍了验证PN结伏安关系特性实验的实验原理,并利用绘图软件Origin7.5对实验数据进行处理.结果表明,PN结的扩散电流和两端的正向电压之间满足指数关系.通过与理论公式的比较,准确地测出了玻尔兹曼常数. 相似文献
78.
79.
80.