全文获取类型
收费全文 | 30764篇 |
免费 | 4134篇 |
国内免费 | 3115篇 |
专业分类
化学 | 14885篇 |
晶体学 | 538篇 |
力学 | 1443篇 |
综合类 | 441篇 |
数学 | 9951篇 |
物理学 | 10755篇 |
出版年
2024年 | 38篇 |
2023年 | 249篇 |
2022年 | 403篇 |
2021年 | 574篇 |
2020年 | 766篇 |
2019年 | 819篇 |
2018年 | 799篇 |
2017年 | 970篇 |
2016年 | 1197篇 |
2015年 | 1080篇 |
2014年 | 1347篇 |
2013年 | 2858篇 |
2012年 | 1622篇 |
2011年 | 1834篇 |
2010年 | 1598篇 |
2009年 | 1862篇 |
2008年 | 1971篇 |
2007年 | 2031篇 |
2006年 | 1814篇 |
2005年 | 1645篇 |
2004年 | 1483篇 |
2003年 | 1429篇 |
2002年 | 1432篇 |
2001年 | 1041篇 |
2000年 | 1112篇 |
1999年 | 945篇 |
1998年 | 844篇 |
1997年 | 674篇 |
1996年 | 559篇 |
1995年 | 489篇 |
1994年 | 403篇 |
1993年 | 318篇 |
1992年 | 278篇 |
1991年 | 216篇 |
1990年 | 185篇 |
1989年 | 132篇 |
1988年 | 149篇 |
1987年 | 118篇 |
1986年 | 110篇 |
1985年 | 115篇 |
1984年 | 110篇 |
1983年 | 48篇 |
1982年 | 81篇 |
1981年 | 44篇 |
1980年 | 50篇 |
1979年 | 56篇 |
1978年 | 24篇 |
1977年 | 18篇 |
1976年 | 13篇 |
1973年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 80 毫秒
71.
Ana Luísa Daniel‐da‐Silva João Carlos Moura Bordado José Miguel Martín‐Martínez 《Journal of Polymer Science.Polymer Physics》2007,45(22):3034-3045
The degree of phase separation in several moisture‐cured poly(urethane urea)s (PUUs) was studied by FTIR spectroscopy, wide angle X‐ray diffraction (WAXD), and temperature‐modulated differential scanning calorimetry (TMDSC). This latter technique was shown to be particularly useful in analysing the degree of phase separation in PUU polymers. Both phase mixing and phase segregation coexisted in the PUUs and the degree of phase separation increased as the urea hard segment (HS) content in the PUU increased. The maximum solubility of urea HSs into the polyol soft segments (SSs) was achieved for 50 wt % urea HS content in diol‐based PUUs, whereas for triol‐based PUUs the highest solubility between HS and SS was reached for lower urea HS amount. Finally, the higher the urea HS content the higher the extent of phase separation in the PUU. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3034–3045, 2007 相似文献
72.
Rhythmic growth of ring‐banded spherulites in blends of liquid crystalline methoxy‐poly(aryl ether ketone) (M‐PAEK) and poly(aryl ether ether ketone) (PEEK) has been investigated by means of differential scanning calorimetry (DSC), polarized light microscopy (PLM), and scanning electron microscopy (SEM) techniques. The measurements reveal that the formation of the rhythmically grown ring‐banded spherulites in the M‐PAEK/PEEK blends is strongly dependent on the blend composition. In the M‐PAEK‐rich blends, upon cooling, an unusual ring‐banded spherulite is formed, which is ascribed to structural discontinuity caused by a rhythmic radial growth. For the 50:50 M‐PAEK/PEEK blend, ring‐banded spherulites and individual PEEK spherulites coexist in the system. In the blends with PEEK as the predominant component, M‐PAEK is rejected into the boundary of PEEK spherulites. The cooling rate and crystallization temperature have great effect on the phase behavior, especially the ring‐banded spherulite formation in the blends. In addition, the effects of M‐PAEK phase transition rate and phase separation rate on banded spherulite formation is discussed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3011–3024, 2007 相似文献
73.
74.
A locally convex space is said to be a Gateaux differentiability space (GDS)provided every continuous convex function defined on a nonempty convex open subset D of the space is densely Gateaux differentiable in D.This paper shows that the product of a GDS and a family of separable Frechet spaces is a GDS,and that the product of a GDS and an arbitrary locally convex space endowed with the weak topology is a GDS. 相似文献
75.
给出了Banach空间的一个增算子不动点定理,将这一定理应用到Banach空间的积分-微分方程,给出了一类积分-微分方程的连续可微最大解和连续可微最小解的存在性定理. 相似文献
76.
本文提出从高分辨电子显微像中,利用光学、全息和部分相干等方法,提取传递函数,制作相位和振幅滤波器,实现解卷,提高高分辨电子显微像的分辨率. 相似文献
77.
M. Faucher D. Garcia E. Antic-Fidancev M. Lemaitre-Blaise 《Journal of Physics and Chemistry of Solids》1989,50(12)
Some structural and spectroscopic features of rare earth orthoaluminates are examined.The trigonal→ orthorhombic transition is studied in a series of NdxSm1−xAlO3 compounds. The evolution of the crystal structure is followed by X-ray analysis and optical absorption. The free ion and crystal field parameters of Nd3+ (4f3 configuration) are determined in LuAlO3:Nd3+.The anomaly of the calculated splitting of the
levels is slight, but well characterized in NdAlO3. The spin correlated crystal field and orbitally correlated crystal field models are tested as well as an empirical correction which was proposed earlier. 相似文献
78.
79.
关于Banach空间中凸泛函的广义次梯度不等式 总被引:2,自引:0,他引:2
本文在前人^[1,2]的基础之上,以凸泛函的次梯度不等式为工具,将Jensen不等式推广到Banach空间中的凸泛函,导出了Banach空间中的Bochner积分型的广义Jensen不等式,给出其在Banach空间概率论中某些应用,从而推广了文献[3—6]的工作. 相似文献
80.
We examine several interesting relationships and expressions involving Fourier-Feynman transform, convolution product and
first variation for functionals in the Fresnel class F(B) of an abstract Wiener space B. We also prove a translation theorem and Parseval's identity for the analytic Feynman integral.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献