全文获取类型
收费全文 | 1326篇 |
免费 | 142篇 |
国内免费 | 101篇 |
专业分类
化学 | 645篇 |
晶体学 | 4篇 |
力学 | 82篇 |
综合类 | 22篇 |
数学 | 569篇 |
物理学 | 247篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 24篇 |
2021年 | 22篇 |
2020年 | 27篇 |
2019年 | 42篇 |
2018年 | 25篇 |
2017年 | 35篇 |
2016年 | 60篇 |
2015年 | 50篇 |
2014年 | 65篇 |
2013年 | 96篇 |
2012年 | 58篇 |
2011年 | 82篇 |
2010年 | 73篇 |
2009年 | 83篇 |
2008年 | 84篇 |
2007年 | 78篇 |
2006年 | 76篇 |
2005年 | 82篇 |
2004年 | 77篇 |
2003年 | 88篇 |
2002年 | 61篇 |
2001年 | 53篇 |
2000年 | 38篇 |
1999年 | 32篇 |
1998年 | 27篇 |
1997年 | 16篇 |
1996年 | 19篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有1569条查询结果,搜索用时 31 毫秒
961.
This paper addresses the use of different slotted pores in rotating membrane emulsification technology.Pores of square and rectangular shapes were studied to understand the effect of aspect ratio (1-3.5) and their orientation on oil droplet formation.Increasing the membrane rotation speed decreased the droplet size,and the oil droplets produced were more uniform using slotted pores as compared to circular geometry.At a given rotation speed,the droplet size was mainly determined by the pore size and the fluid velocity of oil through the pore (pore fluid velocity).The ratio of droplet diameter to the equivalent diameter of the slotted pore increased with the pore fluid velocity.At a given pore fluid velocity and rotation speed,pore orientation significantly influences the droplet formation rate: horizontally disposed pores (with their longer side perpendicular to the membrane axis) generate droplets at double the rate of vertically disposed pores.This work indicates practical benefits in the use of slotted membranes over conventional methods. 相似文献
962.
N. Mebarki K. Benhizia Z. Belghobsi D. Bouaziz 《理论物理通讯》2009,51(4):717-722
The contribution of the two particles Fock states for the production of a heavy quark in proton-pion and photon-pion collisions is studied. It is shown that the effect depends strongly on the produced heavy quark mass, and the choice of the factorization scale. 相似文献
963.
IntroductionSolitonisacomplicatedmathematicalstructurebasedonthenonlinearevolutionequation[1].Thoughsolitonstructuresandpropertiesofthe ( 1 + 1 )_dimensionalnonlinearphysicalmodelshavebeenstudiedwellandunderstoodfurther,thesolitonstructuresinhigherspatialdi… 相似文献
964.
The equivalence between the Bargmann--Wigner (B-W) equations and the
Klein--Gordon (K-G) equations for integral spin, and the Rarita--Schwinger (R-S) equations for half integral spin is established by explicit derivation, starting from the lowest spin cases. It is demonstrated that all the constraints or subsidiary conditions imposed on the K-G or R-S equations are included in the B-W equations. 相似文献
965.
基于Reddy高阶剪切变形理论的Kármám-Donnell型非线性壳体方程,给出复合材料层合剪切圆柱曲板在侧压作用下的后屈曲分析。将壳体屈曲的边界层理论推广到复合材料层合剪切圆柱曲板受侧压作用的情况。相应的奇异摄动法,用于确定圆柱曲板的屈曲荷载和后屈曲平衡路径。分析中同时考虑非线性前屈曲变形和初始几何缺陷的影响。数值算例给出完善和非完善,中等厚度正交铺设层合圆柱曲板的后屈曲荷载-挠度曲线。讨论了横向剪切变形,曲板几何参数,铺层数,铺展方式和初始几何缺陷等各种参数变化的影响。 相似文献
966.
A High-affinity Activator of G551D-CFTR Chloride Channel Identified By High Throughput Screening 总被引:1,自引:0,他引:1
ZHAOLu HECheng-yan LIUYan-li ZHOUHong-lan ZHOUJin-song SHANGDe-jing YANGHong 《高等学校化学研究》2004,20(6):738-742
A stably transfected CHO cell line coexpressing G551D-CFTR and iodide-sensitive yellow fluorescent protein mutant EYFP-H148Q-I152L was successfully established and used as assay model to identify smallmolecule activators of G551D-CFTR chloride channel from 100000 diverse combinatorial compounds by high throughput screening on a customized Beckman robotic system. A bicyclooctane compound was identified to activate G551D-CFTR chloride channel with high-affinity(Kd=1.8 μmol/L). The activity of the bicyclooctane compound is G551D-CFTR-specific, reversible and non-toxic. The G551D-CFTR activator may be useful as a tool to study the mutant G551D-CFTR chloride channel structure and transport properties and as a candidate drug to cure cystic fibrosis caused by G551D-CFTR mutation, 相似文献
967.
968.
P. Reyes C. Rodríguez J. Fernández G. Pecchi J.L.G. Fierro 《Reaction Kinetics and Catalysis Letters》2001,74(1):127-133
The oxidation of methane has been studied in a flow system as a function of the chemical composition of zeolite catalyst using nitrous oxide as oxidant. It is concluded that methanol is a primary oxidation product which may undergo further oxidation to formaldehyde and to carbon oxides. However, it may also undergo conversion over the acidic catalyst to higher hydrocarbons. Reaction with nitrous oxide resulted in the production of carbon oxides, methanol, formaldehyde, C2 - C4 , C5 - C7 nonaromatics, and aromatics. The effect of Fe2 O3 and Al2 O3 , with or without, over HZSM5 on products was studied. 相似文献
969.
Liu Chang-Jun Xue Bingzhang Eliasson Baldur He Fei Li Yang Xu Gen-Hui 《Plasma Chemistry and Plasma Processing》2001,21(3):301-310
Experimental investigation has been conducted to convert methane into higher hydrocarbons in the presence of carbon dioxide within dielectric-barrier discharge (DBD) plasmas. The objectives of cofeed of carbon dioxide are to inhibit carbon deposit and to increase methane conversion. The products from this plasma methane conversion include: (1) syngas (H2+CO), (2) gaseous hydrocarbons containing ethylene, acetylene, and propylene, (3) liquid hydrocarbons, (4) plasma-polymerized film, and (5) oxygenates. The selectivity of products is subject to the DBD plasma-reactive conditions and catalyst applied. The liquid hydrocarbons produced by this way are highly branched, which represents a better fuel production. 相似文献
970.
地里木拉提·吐尔逊 《新疆大学学报(理工版)》2001,18(4):428-431,440
提出一种如不采用相位补偿技术,则施加反馈,组成实际应用电路时往往会引起放大器自激。因此,应用电路中,采用密勒补偿技术,具有一定的应用价值。 相似文献