全文获取类型
收费全文 | 733620篇 |
免费 | 92015篇 |
国内免费 | 120098篇 |
专业分类
化学 | 498689篇 |
晶体学 | 7984篇 |
力学 | 38160篇 |
综合类 | 13584篇 |
数学 | 80239篇 |
物理学 | 307077篇 |
出版年
2024年 | 3899篇 |
2023年 | 12210篇 |
2022年 | 12954篇 |
2021年 | 10654篇 |
2020年 | 10287篇 |
2019年 | 16015篇 |
2018年 | 17687篇 |
2017年 | 13802篇 |
2016年 | 15311篇 |
2015年 | 15957篇 |
2014年 | 26372篇 |
2013年 | 23369篇 |
2012年 | 55793篇 |
2011年 | 70215篇 |
2010年 | 31256篇 |
2009年 | 27169篇 |
2008年 | 60537篇 |
2007年 | 60537篇 |
2006年 | 62001篇 |
2005年 | 58089篇 |
2004年 | 50042篇 |
2003年 | 40114篇 |
2002年 | 35855篇 |
2001年 | 27825篇 |
2000年 | 29663篇 |
1999年 | 14968篇 |
1998年 | 8873篇 |
1997年 | 6889篇 |
1996年 | 12146篇 |
1995年 | 10289篇 |
1994年 | 11449篇 |
1993年 | 12413篇 |
1992年 | 11775篇 |
1991年 | 7464篇 |
1990年 | 7335篇 |
1989年 | 6558篇 |
1988年 | 7131篇 |
1987年 | 6641篇 |
1986年 | 6408篇 |
1985年 | 5960篇 |
1984年 | 3732篇 |
1983年 | 3214篇 |
1982年 | 2564篇 |
1981年 | 2025篇 |
1980年 | 1410篇 |
1979年 | 921篇 |
1978年 | 570篇 |
1966年 | 372篇 |
1965年 | 449篇 |
1948年 | 903篇 |
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
961.
HUA Jianjun LIU Yanhong & ZHANG Zhihe . Institute of Physics Chinese Academy of Sciences Beijing China . College of Biomedical Engineering Capital University of Medical Sciences Beijing China Correspondence should be addressed to Hua Jianjun 《中国科学G辑(英文版)》2004,(1)
Adustyplasmacanbedefinedasacomplicatedplasmacontainingsmallsolidmattercalleddustgrainsordustparticles,whichareusuallychargednegatively,duetoelectronshighermobilitythanion,bycollectingelectronsandionsfromthebackgroundplasma.Theuniverseisfilledwithdustyplasmassuchasplanetaryrings,comettails,andnebulae.Also,inindustrialplasmaprocessing,particulatessuspendedinplasmaarethemajorcontaminationinsemiconductormanufacture.Studiesondustyplasmahavebeenextendedtofar-flungtopicssuchaswaves,instabilities,stro… 相似文献
962.
YBa2Cu3O7-x (YBCO) bulk is one of the most important high temperature superconducting materials for magnetic levitation applications, because it has a high magnetic irreversibility field Hirr at liquid nitrogen temperature, and can grow into large grains. The levitation force of YBCO bulk is proportional to the critical current density (Jc) and grain radius (r)[1], so higher Jc and r are appreciated for YBCO bulks to achieve higher levitation force. Now single-domain YBCO bulks up to s… 相似文献
963.
Polarization spectra of rubidium atoms were investigated with different uncrossed angles between the polarizer and the analyzer. The variation of the spectra was derived theoretically as a function of arbitrary angle, and measured experimentally for different angles. The spectral profile of D2 line of rubidium was further used to stabilize the frequency of a diode laser. It was demonstrated that the laser linewidth was reduced to 2 MHz. 相似文献
964.
The Δ-scaling method has been applied to ultra-relativistic p p,C C and Pb Pb collision data simulated using a high-energy Monte Carlo package,LUCIAE 3.0.The Δ-scaling is found to be valid for some physical variables,such as charged particle multiplicity,strange particle multiplicity and number of binary nucleon-nucleon-nucleon collisions from these simulated nucleus-nucleus collisions over an extended energy ranging from E1ab=20 to 200A GeV.In addition we derive the information entropy from the multiplicity distribution as a function of beam energy for these collisions. 相似文献
965.
A novel compensation method for temperature-dependent gain tilt of L-band erbium-doped fiber amplifier (L-EDFA) is proposed, in which the attenuation between stages is the only parameter to be adjusted. A simple linear relationship between the attenuation and the erbium fiber coil temperature was derived theoretically. When the erbium fiber coil temperature cycles from 26 to 70℃, the gain tilt variation less than 0.3 dB is achieved experimentally by adjusting only the pre-inserted variable optical attenuator (VOA). 相似文献
966.
A G 4.0 dendrimer-like poly (amido amine) (PAMAM) based on silica nanoparticles was fabricated via a divergent approach.It was built from γ-aminopropyi silica nanoparfides (APSN) core via repetitive addition of acrylate (MA) and hexylenediamine (HDA). FT-IR and EA were used to monitor the progress of dendrimer during each step. The amino group content of the resulting product increased from 0.49 to 3.72 mmol/g after the 4th generation. In addition, the percentage of grafting increased with increasing generation and reached to 65.9% after 4th generation. It was found that the resulting silica nanoparticles could be dispersed in methanol with a mean hydrodynamic particle diameter of 152.7 nm although the silica nanoparticles had agglomerated during the storage period. 相似文献
967.
968.
969.
970.
今年是湖北省高考单独命题的第一年 ,也是使用新教材的第一次高考。总体上说 ,数学试卷体现了“平稳过渡”的原则 ,试卷结构合理 ,注重基础 ,强调应用 ,突出能力。具体有以下一些特色 :1 .循纲务本 ,注重基础 ,不出偏题、怪题。有的题是对课本习题的改编 ,如第 1 6题出自高三教材。有的题改编于以往的高考题 ,如第 1 2题。2 .题型平淡无奇 ,但考查突出能力。如立体几何 (第 1 8题 )和解析几何表现最为明显 ,都是非常常见的题 ,给我们透出要减少重复教学 ,反对题海战术 ,培养学习兴趣 ,理解数学本质 ,提高基本能力与素质的信息。3 .突出新增… 相似文献