全文获取类型
收费全文 | 7060篇 |
免费 | 711篇 |
国内免费 | 496篇 |
专业分类
化学 | 2430篇 |
晶体学 | 78篇 |
力学 | 2458篇 |
综合类 | 66篇 |
数学 | 993篇 |
物理学 | 2242篇 |
出版年
2024年 | 11篇 |
2023年 | 83篇 |
2022年 | 177篇 |
2021年 | 182篇 |
2020年 | 266篇 |
2019年 | 199篇 |
2018年 | 186篇 |
2017年 | 223篇 |
2016年 | 300篇 |
2015年 | 226篇 |
2014年 | 297篇 |
2013年 | 684篇 |
2012年 | 265篇 |
2011年 | 362篇 |
2010年 | 286篇 |
2009年 | 381篇 |
2008年 | 374篇 |
2007年 | 424篇 |
2006年 | 374篇 |
2005年 | 300篇 |
2004年 | 318篇 |
2003年 | 274篇 |
2002年 | 252篇 |
2001年 | 225篇 |
2000年 | 192篇 |
1999年 | 196篇 |
1998年 | 180篇 |
1997年 | 140篇 |
1996年 | 145篇 |
1995年 | 125篇 |
1994年 | 95篇 |
1993年 | 82篇 |
1992年 | 68篇 |
1991年 | 63篇 |
1990年 | 61篇 |
1989年 | 41篇 |
1988年 | 44篇 |
1987年 | 18篇 |
1986年 | 29篇 |
1985年 | 26篇 |
1984年 | 21篇 |
1983年 | 10篇 |
1982年 | 23篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1971年 | 9篇 |
1957年 | 9篇 |
排序方式: 共有8267条查询结果,搜索用时 31 毫秒
81.
基于界面跟踪方法的汽蚀模型和算法的有效性验证 总被引:1,自引:1,他引:0
针对两相附着汽蚀流动机理,基于界面跟踪方法发展了新的汽蚀模型和算法。所发展的汽蚀模型和算法不仅考虑了液相/气相界面处的压力差,而且考虑了耦合Reynolds-Averaged Navier-Stokes方程求解技术得到的流场压力梯度信息来迭代计算附着汽蚀形状。采用具有试验数据的半球形头部圆柱体汽蚀绕流作为算例来验证所提出的汽蚀模型和算法的有效性。采用不同的网格数和松弛因子数值验证了发展的汽蚀模型和算法的有效性。三种汽蚀数下的数值计算结果得到的压力系数分布与试验数据完全吻合。结果表明所提出的汽蚀模型和算法能够准确模拟出汽蚀发生点和汽蚀长度。 相似文献
82.
Two-dimensional antiplane time-harmonic Green’s functions for a circular inhomogeneity with an imperfect interface are derived. Here the linear spring model with vanishing thickness is employed to characterize the imperfect interface. Explicit expressions for the displacement and the stress fields induced by time-harmonic antiplane line forces located both in the unbounded matrix and in the circular inhomogeneity are presented. When the circular frequency approaches zero, our results reduce to those for the static case. Numerical results are presented to show the influence of the frequency and the imperfection of the interface on the stress and displacement fields. 相似文献
83.
The composting of organic solid waste, the mixture of fruit and vegetable leftovers enriched with night soil, was investigated
in a closed thermally insulated reactor. It was found that 80.9 % of the original substrate biodegraded after 14 days. A mathematical
model of the column reactor was proposed where the biodegradation rate of the organic solid waste was described using simple
n-thorder kinetics. A good prediction of process performance was obtained using the proposed kinetics and experimentally obtained
reaction heat.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
84.
为了求解各向异性接合材料界面端部奇异性应力场,建立了一种新型杂交元模型.该模型的独特之处在于:基于有限元特征法得到的奇异性场数值特征解建立了一种新型界面端奇异单元.通过算例证明,新型杂交元模型能够利用较少的单元数获得较为精确的数值结果.当前模型应用范围广泛,能够用于复杂结构的界面端部场求解. 相似文献
85.
86.
87.
Recyclable antimicrobial magnetic nanoparticles, Fe3O4@P(St-co-AcQAC), were prepared through surfactantfree seeded emulsion polymerization involving a polymerizable, hydrophobic quaternary ammonium compound (QAC). These antimicrobial magnetic nanoparticles demonstrated excellent antimicrobial activities against both Grampositive and Gram-negative bacteria, and can be reused for multiple times. 相似文献
88.
P.M.?Kosaka Y.?Kawano M.C.?Salvadori D.F.S.?PetriEmail author 《Cellulose (London, England)》2005,12(4):351-359
The adsorption of cellulose acetate (CA), cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) from solutions
prepared in acetone onto silicon wafers led to ultrathin films, which were characterized by ellipsometry, atomic force microscopy
(AFM) and contact angle measurements. The polysaccharides films were characterized in the air just after their formation and
after annealing at temperatures higher than their glass transition temperature or melt temperature. The films thickness close
to 2 nm and surface roughness did not vary significantly upon annealing. AFM images revealed the presence of small clumps
dispersed on a homogeneous layer, which covered completely the Si wafers. Such topographic details were also observed after
annealing. However, upon annealing the films surfaces changed from hydrophilic to hydrophobic, evidencing molecular re-orientation
at the solid–air interface. The adhesion of bovine serum albumin (BSA) and lipase onto the cellulose esters films was quantified
in order to evaluate the possibility of applying such films as selective support for biomolecules. 相似文献
89.
90.
Pappa A. Kyriakou S. Mikedi K. Tzamtzis N. Statheropoulos M. 《Journal of Thermal Analysis and Calorimetry》2004,78(2):415-426
The design, the abilities and a characteristic application of an in-house made interface for combining thermogravimetry (TG)
with mass spectrometry (MS) are presented. The TG-MS interface consists mainly of three co-axial tubes. The position of the
intermediate tube was determined after calculation of the temperature profile at the TG furnace exit tube. The inner tube
position was determined taking into consideration its protection against condensation of heavy molecules and the time delay
for the transfer of the evolved gases. This interface allows either continuous sampling and transferring of the evolved gases
from the TG to the MS or repetitive introduction of short sampling pulses of TG evolved gases to MS. The interface is capable
of coupling various commercial instruments. In the present work two configurations of this interface are demonstrated. Finally
an example of application of this interface on forest fuel pyrolysis is presented.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献