全文获取类型
收费全文 | 14464篇 |
免费 | 1284篇 |
国内免费 | 1228篇 |
专业分类
化学 | 8533篇 |
晶体学 | 233篇 |
力学 | 1342篇 |
综合类 | 52篇 |
数学 | 337篇 |
物理学 | 6479篇 |
出版年
2024年 | 21篇 |
2023年 | 208篇 |
2022年 | 319篇 |
2021年 | 301篇 |
2020年 | 457篇 |
2019年 | 374篇 |
2018年 | 357篇 |
2017年 | 404篇 |
2016年 | 569篇 |
2015年 | 597篇 |
2014年 | 696篇 |
2013年 | 943篇 |
2012年 | 654篇 |
2011年 | 993篇 |
2010年 | 840篇 |
2009年 | 1046篇 |
2008年 | 919篇 |
2007年 | 1137篇 |
2006年 | 925篇 |
2005年 | 711篇 |
2004年 | 732篇 |
2003年 | 606篇 |
2002年 | 462篇 |
2001年 | 385篇 |
2000年 | 347篇 |
1999年 | 309篇 |
1998年 | 272篇 |
1997年 | 225篇 |
1996年 | 189篇 |
1995年 | 152篇 |
1994年 | 140篇 |
1993年 | 96篇 |
1992年 | 79篇 |
1991年 | 93篇 |
1990年 | 48篇 |
1989年 | 36篇 |
1988年 | 46篇 |
1987年 | 32篇 |
1986年 | 38篇 |
1985年 | 23篇 |
1984年 | 24篇 |
1983年 | 13篇 |
1982年 | 24篇 |
1981年 | 23篇 |
1980年 | 22篇 |
1979年 | 21篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Mohammed Ahmed Shehab Nikita Sharma Andrea Valsesia Gbor Karacs Ferenc Kristly Tams Kos Anett Katalin Lesk Lilla Nnai Klara Hernadi Zoltn Nmeth 《Molecules (Basel, Switzerland)》2022,27(9)
Nowadays, the use of hybrid structures and multi-component materials is gaining ground in the fields of environmental protection, water treatment and removal of organic pollutants. This study describes promising, cheap and photoactive self-supported hybrid membranes as a possible solution for wastewater treatment applications. In the course of this research work, the photocatalytic performance of titania nanowire (TiO2 NW)-based hybrid membranes in the adsorption and degradation of methylene blue (MB) under UV irradiation was investigated. Characterization techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffractometry (XRD) were used to study the morphology and surface of the as-prepared hybrid membranes. We tested the photocatalytic efficiency of the as-prepared membranes in decomposing methylene blue (MB) under UV light irradiation. The hybrid membranes achieved the removal of MB with a degradation efficiency of 90% in 60 min. The high efficiency can be attributed to the presence of binary components in the membrane that enhanced both the adsorption capability and the photocatalytic ability of the membranes. The results obtained suggest that multicomponent hybrid membranes could be promising candidates for future photocatalysis-based water treatment technologies that also take into account the principles of circular economy. 相似文献
53.
A. Seyfaee M. Lashkarbolooki D. Mowla 《Journal of Dispersion Science and Technology》2013,34(3):312-319
In this article, the effect of temperature, pressure, and flow rate on deposition rate has been investigated by using chemical analysis method for calculating the deposit thickness and comparing to heat transfer and pressure drop methods. To do so, an experimental high pressure flow loop setup was designed and constructed to conduct various experiments. Caliper readings at the end of each test showed the chemical analysis method in comparison to the heat transfer and pressure drop methods is superior for deposit thickness calculation. 相似文献
54.
S. B. Fisher 《辐射效应与固体损伤》2013,168(3-4):173-177
The various factors influencing the nucleation of radiation damage in the HVEM are reviewed. A method for obtaining quantitative information from observations is given. The effect of reirradiation at room temperature on the damage formed at elevated temperatures is shown. This effect may give experimental information concerning the strain fields surrounding large dislocation loops. 相似文献
55.
J. C. Lee H. N. Najm S. Lefantzi J. Ray M. Frenklach M. Valorani 《Combustion Theory and Modelling》2013,17(1):73-102
We demonstrate the feasibility of a new strategy for the construction of an adaptive chemistry model that is based on an explicit integrator stabilized by an approximation of the Computational Singular Perturbation (CSP)-slow-manifold projector. We examine the effectiveness and accuracy of this technique first using a model problem with variable stiffness. We assess the effect of using an approximation of the CSP-slow-manifold by either reusing the CSP vectors calculated in previous steps or from a pre-built tabulation. We find that while accuracy is preserved, the associated CPU cost was reduced substantially by this method. We used two ignition simulations – hydrogen–air and heptane–air mixtures – to demonstrate the feasibility of using the new method to handle realistic kinetic mechanisms. We test the effect of utilizing an approximation of the CSP-slow-manifold and find that its use preserves the order of the explicit integrator, produces no degradation in accuracy, and results in a scheme that is competitive with traditional implicit integration. Further analysis on the performance data demonstrates that the tabulation of the CSP-slow-manifold provides an increasing level of efficiency as the size of the mechanism increases. From the software engineering perspective, all the machinery developed is Common Component Architecture compliant, giving the software a distinct advantage in the ease of maintainability and flexibility in its utilization. Extension of this algorithm is underway to implement an automated tabulation of the CSP-slow-manifold for a detailed chemical kinetic system either off-line, or on-line with a reactive flow simulation code. 相似文献
56.
Xi Jiang Qi Liao Jianjun Zhou Zhaohui Wang Chiming Chan Lin Li 《Journal of Polymer Science.Polymer Physics》2013,51(11):907-914
We have developed a morphologic method to investigate the relaxation processing of the stretched polymer chains in melts, in which an atomic force microscope probe was used to shear the surface of an isotactic polypropylene melt to obtain the isolated shish‐kebab structure. We present the results of the time dependence of length of the isolated shish‐kebab structure and the stress dependence of the kebab density along the direction of shish in this paper. Our results demonstrate that the shear‐oriented polymer melts show the relaxation dynamics of worm‐like chain where the length deficit of the isolated shish‐kebab structure is scaled with the relaxation time as a power of 1/3. The melting behavior of shish‐kebab structure was also investigated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 907–914 相似文献
57.
58.
59.
60.
M. A. Bueno 《Foundations of Physics Letters》1994,7(4):393-400
In this work it is derived Phipps's Lagrangian function and Phipps's Hamiltonian function. This allows the utilization of Phipps's interaction in the Lagrangian and Hamiltonian frameworks.Dedicated to Thomas E. Phipps, Jr. on the occasion of his 70th birthday (1995). 相似文献