全文获取类型
收费全文 | 182620篇 |
免费 | 14556篇 |
国内免费 | 21711篇 |
专业分类
化学 | 108293篇 |
晶体学 | 1709篇 |
力学 | 11886篇 |
综合类 | 2546篇 |
数学 | 43612篇 |
物理学 | 50841篇 |
出版年
2024年 | 242篇 |
2023年 | 1505篇 |
2022年 | 3714篇 |
2021年 | 3791篇 |
2020年 | 4483篇 |
2019年 | 4505篇 |
2018年 | 3963篇 |
2017年 | 5209篇 |
2016年 | 5773篇 |
2015年 | 4938篇 |
2014年 | 7108篇 |
2013年 | 13135篇 |
2012年 | 10263篇 |
2011年 | 9714篇 |
2010年 | 8315篇 |
2009年 | 11248篇 |
2008年 | 11819篇 |
2007年 | 12181篇 |
2006年 | 11170篇 |
2005年 | 9480篇 |
2004年 | 8688篇 |
2003年 | 7880篇 |
2002年 | 8554篇 |
2001年 | 5974篇 |
2000年 | 5695篇 |
1999年 | 5256篇 |
1998年 | 4697篇 |
1997年 | 3811篇 |
1996年 | 3275篇 |
1995年 | 3014篇 |
1994年 | 2681篇 |
1993年 | 2259篇 |
1992年 | 2100篇 |
1991年 | 1591篇 |
1990年 | 1318篇 |
1989年 | 1212篇 |
1988年 | 1009篇 |
1987年 | 773篇 |
1986年 | 693篇 |
1985年 | 729篇 |
1984年 | 714篇 |
1983年 | 379篇 |
1982年 | 608篇 |
1981年 | 617篇 |
1980年 | 523篇 |
1979年 | 525篇 |
1978年 | 408篇 |
1977年 | 346篇 |
1976年 | 278篇 |
1973年 | 190篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
电路过渡过程所列方程是微分方程,本文中采用的是方框图模型分析法,即将微分方程的复杂示解分解成最基本的加(减)、乘(除)、积分(微分)、增益等运算,采用VB设计用户界面产进行计算,并给出了一算例。 相似文献
102.
D. J. Plazek C. A. Bero S. Neumeister G. Floudas G. Fytas K. L. Ngai 《Colloid and polymer science》1994,272(11):1430-1438
By making creep and recoverable creep measurements of a nearly monodisperse low molecular weight poly(methyl phenyl siloxane) sample, we have found on decreasing temperature towardsT
g that there is continuously a change in the viscoelastic spectrum concomitant with a decrease of the steadystate recoverable compliance. This behavior is exactly the same as previously observed in low molecular weight poly(styrene), proving that this spectacular anomaly in the viscoelasticity of low molecular weight polymers is general and deserves an explanation. Photon correlation spectroscopic measurements performed on the same sample have extended the observation of the viscoelastic response to shorter times and the result corroborates the trend of variation established by the creep data.Dedicated to Prof.Dr. E. W. Fischer on his 65th Birthday. Prof.Dr. Fischer is known for his valuable contribution to fosterine, international collaboration of research in polymer science. This work is an example of his contribution because it would not be possible without him bringing us together. One of us (KLN) would like to take this opportunity to thank Prof. Dr. Fischer for his unwaiving support of the 1st (Crete) and the 2nd (Alicante) International Discussion Meeting on Relaxations in Complex Systems 相似文献
104.
We prove that to most of the known hypercyclic operators A on separable Banach spaces there exist compact (compact convex, compact connected) subsets K of E such that each compact (compact convex, compact connected) subset of E can be approximated with respect to Hausdorff's distance by for suitable .
Received July 8, 1997, in final form October 17, 1997 相似文献
105.
It is proved that for any integerk≥ 54 000, there isN
k
>0 depending onk only such that every even integer ≥N
k
is a sum of two odd prime numbers andk powers of 2.
Project partially supported by RGC Research Grant (No.HKU 7122/97P) and Post-Doctoral Fellowship of the University of Hong
Kong. 相似文献
106.
107.
Boundedness of commutators on homogeneous Herz spaces 总被引:9,自引:0,他引:9
The boundedness on homogeneous Herz spaces is established for a large class of linear commutators generated by BMO(R
n
) functions and linear operators of rough kernels which include the Calderón-Zygmund operators and the Ricci-Stein oRfiUatory
singular integrals with rough kernels.
Project supponed in pan by the National h’atural Science Foundation of China (Grant No. 19131080) and the NEDF of China. 相似文献
108.
M. Georgelin A. Pocheau 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(2):169-174
The polycrystalline perovskitelike manganese oxides La1-xAxMnO (A = Na, and K, ) have been fabricated by sol-gel technique. For all the compositions explored in this work, the average manganese oxidation
state is practically constant, at for A = Na, and for A = K, respectively. A close relationship is confirmed to hold between the Curie temperature (Tc) and the bond distance of Mn-O. Results of magnetic measurements show that these materials can be utilized as suitable candidates
for magnetic refrigerants with wide applied temperature span, for their significant entropy change and the easily tuned Curie
temperature.
Received: 12 September 1997 / Revised: 18 December 1997 / Accepted: 21 January 1998 相似文献
109.
110.
在氢化丁苯共聚物13C-NMR谱脂肪碳部分谱带归属的基础上,根据各谱带的主要来源,推导出六个二单元浓度的计算公式。计算出二单元、一单元的相对含量,各结构单元的数均序列长度、嵌段含量和其它结构参数。加氢前后的1H-和13C-NMR谱的组成计算结果基本一致。初步探讨了作为粘度指数改进剂的氢化丁苯共聚物微观结构与性能的关系,为合成提供了依据。 相似文献