全文获取类型
收费全文 | 3015篇 |
免费 | 193篇 |
国内免费 | 48篇 |
专业分类
化学 | 2106篇 |
晶体学 | 37篇 |
力学 | 125篇 |
综合类 | 2篇 |
数学 | 385篇 |
物理学 | 601篇 |
出版年
2024年 | 33篇 |
2023年 | 63篇 |
2022年 | 134篇 |
2021年 | 299篇 |
2020年 | 183篇 |
2019年 | 178篇 |
2018年 | 155篇 |
2017年 | 131篇 |
2016年 | 197篇 |
2015年 | 135篇 |
2014年 | 148篇 |
2013年 | 240篇 |
2012年 | 212篇 |
2011年 | 244篇 |
2010年 | 136篇 |
2009年 | 125篇 |
2008年 | 128篇 |
2007年 | 107篇 |
2006年 | 78篇 |
2005年 | 63篇 |
2004年 | 41篇 |
2003年 | 37篇 |
2002年 | 36篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有3256条查询结果,搜索用时 31 毫秒
921.
对HL-2A 偏滤器靶板和固定孔栏位置的石墨瓦进行了离线激光诱导击穿光谱(LIBS)测量,比较分析了沉积行为,初步得到了不同位置沉积层粒子种类(Fe、Si、H、D 等元素)及其深度的变化。与飞行时间二次离子质谱仪(TOF-SIMS)所得结果进行了对比,发现离子深度变化形貌趋同。根据沉积层有效信号激光数,得到激光烧蚀速率约为270nm/脉冲。 相似文献
922.
Muhammad Haji Hanif Muddasir Tahiri Iftikhar Ahmad Versiani Muhammad Ali Shah Faheem Khaliq Obaid Ali Syed Tahir Ahmed Safeer 《Research on Chemical Intermediates》2018,44(10):6387-6400
Research on Chemical Intermediates - Among the reactive oxygen species, the superoxide anion radical (O 2 ·? ) has a fundamental role in several biological functions. Consequently, its... 相似文献
923.
Two‐dimensional steady, laminar, and incompressible flow of a micropolar fluid in a channel with no‐slip at one wall and constant uniform injection through the other wall is considered for different values of the Reynolds number R. The main flow stream is superimposed by constant injection velocity at the porous wall. The micropolar model introduced by Eringen is used to describe the working fluid. An extension of Berman's similarity transformations is used to reduce governing equations to a set of nonlinear coupled ordinary differential equations (ODEs) in dimensionless form. An algorithm based on finite difference method is employed to solve these ODEs and Richardson's extrapolation is used to obtain higher order accuracy. It has been found that the magnitude of shear stress increases strictly at the impermeable wall whereas it decreases steadily at the permeable wall, by increasing the injection velocity. The maximum value of streamwise velocity and that of the microrotation both increase with increasing the magnitude of R. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
924.
925.
MUHAMMAD Naeem Ahmed IFZAN Arshad WANG Bo SHAHID Hameed BILAL Ahmad Khan KHAWAJA Ansar Yasin MUHAMMAD Moazzam Naseer 《结构化学》2014,(12)
One-pot three component reaction was used to synthesize 1,4,5-trisubstituted 1,2,3-triazole(A) from the corresponding acid chloride, benzyl azide and 1-copper(I) phenylethyne. The molecular structure was determined by single-crystal X-ray analysis. The compound crystallizes in the orthorhombic space group Pbca, a = 14.9815(14), b = 9.6496(10), c = 25.528(2) A, Z = 8. Furthermore, crystal packing demonstrated a molecular wall-like structure based on supramolecular chains of A, stabilized by CH···O, CH···Br, N···C and CH···π interactions. Molecular geometry in the ground state has been determined by density functional theory(DFT) by B3LYP/6-311G* basis set and compared with the experimental data. The computed vibrational frequencies are compared with the experimental FT-IR data and frontier molecular orbital analyses were performed at the same level of theory. Theoretical parameters are in good agreement with the corresponding X-ray diffraction values. 相似文献
926.
927.
Muhammad Anwar Shameem Dr. Andreas Orthaber 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):10718-10735
This Minireview describes recent advances of organophosphorus compounds as opto‐electronic materials in the field of organic electronics. The progress of (hetero‐) phospholes, unsaturated phosphanes, and trivalent and pentavalent phosphanes since 2010 is covered. The described applications of organophosphorus materials range from single molecule sensors, field effect transistors, organic light emitting diodes, to polymeric materials for organic photovoltaic applications. 相似文献
928.
Mehmood Ahmer Khan Sajid Iqbal Muhammad Saleem Butt Adnan Saeed 《Journal of Thermal Analysis and Calorimetry》2022,147(12):6983-6992
Journal of Thermal Analysis and Calorimetry - The problem of entropy generation in mixed convection flow of incompressible viscous fluid along an isothermal vertical wavy cone is investigated... 相似文献
929.
Malik Adnan Nafees Ayesha Ali Akram Butt Muhammad Naeem 《The European Physical Journal C - Particles and Fields》2022,82(2):1-12
The European Physical Journal C - Much theoretical effort and automatization are required to confront new physics models with experimental data for many types of particle reactions at future... 相似文献
930.