全文获取类型
收费全文 | 4870篇 |
免费 | 98篇 |
国内免费 | 12篇 |
专业分类
化学 | 2448篇 |
晶体学 | 131篇 |
力学 | 225篇 |
数学 | 666篇 |
物理学 | 1510篇 |
出版年
2022年 | 56篇 |
2021年 | 72篇 |
2020年 | 77篇 |
2019年 | 88篇 |
2018年 | 64篇 |
2017年 | 83篇 |
2016年 | 125篇 |
2015年 | 102篇 |
2014年 | 126篇 |
2013年 | 344篇 |
2012年 | 235篇 |
2011年 | 260篇 |
2010年 | 166篇 |
2009年 | 155篇 |
2008年 | 197篇 |
2007年 | 214篇 |
2006年 | 164篇 |
2005年 | 170篇 |
2004年 | 135篇 |
2003年 | 94篇 |
2002年 | 90篇 |
2001年 | 64篇 |
2000年 | 52篇 |
1999年 | 53篇 |
1998年 | 50篇 |
1996年 | 53篇 |
1995年 | 48篇 |
1994年 | 56篇 |
1993年 | 71篇 |
1992年 | 63篇 |
1991年 | 48篇 |
1990年 | 58篇 |
1989年 | 52篇 |
1988年 | 62篇 |
1987年 | 51篇 |
1986年 | 30篇 |
1985年 | 73篇 |
1984年 | 95篇 |
1983年 | 57篇 |
1982年 | 63篇 |
1981年 | 70篇 |
1980年 | 71篇 |
1979年 | 72篇 |
1978年 | 68篇 |
1977年 | 62篇 |
1976年 | 57篇 |
1975年 | 44篇 |
1974年 | 47篇 |
1973年 | 55篇 |
1972年 | 34篇 |
排序方式: 共有4980条查询结果,搜索用时 15 毫秒
201.
202.
Journal of Thermal Analysis and Calorimetry - In the present framework, the combined effect of magnetic field (Hartmann number, Ha), angle of inclination $$(\alpha )$$ , nanoparticle volume... 相似文献
203.
Crystallography Reports - The communication deals with the eco-friendly synthesis and X-ray crystal structure of an organic carbonitrile, namely... 相似文献
204.
Nonlinear Dynamics - We investigate the control of friction-induced vibration in a precision motion stage under the effect of the LuGre friction dynamics. We consider a lumped parameter model of... 相似文献
205.
206.
Ganesh Narayanan Yavuz Caydamli Halil Tekinalp Ishita Matai Ramiz Boy Ching-Chang Chung Jialong Shen Bhupender S. Gupta Alan E. Tonelli 《Journal of polymer science. Part A, Polymer chemistry》2018,56(22):1529-1537
Three pseudorotaxanes (PpR) comprised of poly (ε-caprolactone) (PCL) and α-cyclodextrin (α-CD) with varying stoichiometric ratios were synthesized and characterized. Wide-angle X-ray diffraction (WAXD) and thermogravimetric (TGA) analyses provided conclusive evidence for complexation between the guest PCL and host α-CD. The as-synthesized and characterized PpRs were used at 10 and 20% concentrations as nucleants to promote the bulk PCL crystallization in composite films. Both WAXD and TGA provided evidence for intact PpR structures in the composite films. Isothermal differential scanning calorimetric (I-DSC) analyses, performed at various crystallization temperatures demonstrated significant differences in the crystallization patterns among the composite films. In addition, I-DSC analyses showed higher Avrami constant values (n) in the PpR-nucleated composite PCL films (n ~ 3), indicating 3-dimensional crystal growth. In the case of neat PCL films, however, lower n values indicated crystal growth in 1-dimensions or 2-dimensions. Moreover, atomic force microscopic analyses showed large crests and pits in PpR-nucleated PCL composites, with irregular morphologies leading to higher surface roughness. To the contrary, the crests and pits were much smaller in the neat PCL films, resulting in lower surface roughness values. Finally, mechanical testing revealed higher tensile strength for PpR-nucleated PCL composites films, demonstrating larger load bearing capabilities. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1529–1537 相似文献
207.
We seek to develop network algorithms for function computation in sensor networks. Specifically, we want dynamic joint aggregation, routing, and scheduling algorithms that have analytically provable performance benefits due to in-network computation as compared to simple data forwarding. To this end, we define a class of functions, the Fully-Multiplexible functions, which includes several functions such as parity, MAX, and kth-order statistics. For such functions we characterize the maximum achievable refresh rate of the network in terms of an underlying graph primitive, the min-mincut. In acyclic wireline networks we show that the maximum refresh rate is achievable by a simple algorithm that is dynamic, distributed, and only dependent on local information. In the case of wireless networks we provide a MaxWeight-like algorithm with dynamic flow-splitting, which is shown to be throughput-optimal. 相似文献
208.
209.
S. C. Tripathi K. K. Gupta M. Bindu P. M. Gandhi 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):657-661
Present investigation describes our study on photochemical generation of uranous ions and consequent degradation of solvent in the uranium loaded 30 % Tributyl phosphate-n-dodecane-nitric acid system. Samples of 30 % TBP-n-dodecane loaded with uranium were subjected to UV photolysis at 254, 300 and 350 nm respectively. Wavelength dependent formation of U(IV) has been determined spectrophotometrically by measuring absorbance at 656 nm. Additionally, photochemical yield of U(IV) has also been estimated semi quantitatively as a function of time of photolysis. The changes in the solvent composition under different photochemical conditions have been studied by examination of comparative gas chromatographic profiles of the solvent before and after photolysis. Among the wavelength of photo irradiation studied, the yield of U(IV) was found to be optimum at 300 nm with least degradation of PUREX solvent. 相似文献