全文获取类型
收费全文 | 4888篇 |
免费 | 149篇 |
国内免费 | 25篇 |
专业分类
化学 | 3138篇 |
晶体学 | 47篇 |
力学 | 201篇 |
数学 | 595篇 |
物理学 | 1081篇 |
出版年
2022年 | 55篇 |
2021年 | 81篇 |
2020年 | 77篇 |
2019年 | 72篇 |
2018年 | 48篇 |
2017年 | 40篇 |
2016年 | 89篇 |
2015年 | 95篇 |
2014年 | 116篇 |
2013年 | 258篇 |
2012年 | 271篇 |
2011年 | 323篇 |
2010年 | 206篇 |
2009年 | 161篇 |
2008年 | 299篇 |
2007年 | 256篇 |
2006年 | 282篇 |
2005年 | 229篇 |
2004年 | 206篇 |
2003年 | 147篇 |
2002年 | 175篇 |
2001年 | 111篇 |
2000年 | 116篇 |
1999年 | 71篇 |
1998年 | 66篇 |
1997年 | 54篇 |
1996年 | 70篇 |
1995年 | 74篇 |
1994年 | 64篇 |
1993年 | 65篇 |
1992年 | 46篇 |
1991年 | 68篇 |
1990年 | 40篇 |
1989年 | 37篇 |
1988年 | 45篇 |
1987年 | 35篇 |
1986年 | 37篇 |
1985年 | 54篇 |
1984年 | 48篇 |
1983年 | 43篇 |
1982年 | 46篇 |
1981年 | 26篇 |
1980年 | 36篇 |
1979年 | 41篇 |
1978年 | 32篇 |
1977年 | 40篇 |
1976年 | 21篇 |
1975年 | 25篇 |
1974年 | 24篇 |
1973年 | 20篇 |
排序方式: 共有5062条查询结果,搜索用时 15 毫秒
1.
2.
Crosslinked poly(ethylene oxide) containing siloxanes fabricated through thiol‐ene photochemistry
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Victor A. Kusuma Elliot A. Roth William P. Clafshenkel Steven S. Klara Xu Zhou Surendar R. Venna Erik Albenze David R. Luebke Meagan S. Mauter Richard R. Koepsel Alan J. Russell David Hopkinson Hunaid B. Nulwala 《Journal of polymer science. Part A, Polymer chemistry》2015,53(13):1548-1557
Homogenous amphiphilic crosslinked polymer films comprising of poly(ethylene oxide) and polysiloxane were synthesized utilizing thiol‐ene “ click ” photochemistry. A systematic variation in polymer composition was Carried out to obtain high quality films with varied amount of siloxane and poly(ethylene oxide). These films showed improved gas separation performance with high gas permeabilities with good CO2/N2 selectivity. Furthermore, the resulting films were also tested for its biocompatibility, as a carrier media which allow human adult mesenchymal stem cells to retain their capacity for osteoblastic differentiation after transplantation. The obtained crosslinked films were characterized using differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis, FTIR, Raman‐IR , and small angle X‐ray scattering. The synthesis ease and commercial availability of the starting materials suggests that these new crosslinked polymer networks could find applications in wide range of applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1548–1557 相似文献
3.
Chromatographia - The reversed phase behaviour of high molecular mass polystyrenes was investigated on C18 bonded phase columns with ethyl acetate-methanol and ethyl acetateacetonitrile mobile... 相似文献
4.
5.
Band bending at the Ni/Si(100)-2×1 interface has been monitored by using Si 2p core level photoemission spectra. Two nickel-induced Si 2p components appear in the initial interaction between Ni and Si(100)-2×1, which is confined at the top surface and the first subsurface layers. At Ni coverage less than 0.0375 ML, Ni atoms prefer the adamantane interstitial sites on the first subsurface, but switch to the pedestal sites on Si dimer rows at higher Ni coverage. The change in the preferred occupation sites of Ni atoms on the Si(100)-2×1 surface strongly affects the amount of band bending shift. The shift towards higher binding energy, when Ni atoms occupy the adamantane interstitial sites, is attributed to metal-induced-gap states. While Ni atoms occupy the pedestal sites, the band bending shift is reduced which is attributed to the passivation of surface states. 相似文献
6.
Aiqing Zhang Xiangdan Li Changwoon Nah Keejun Hwang Myong‐Hoon Lee 《Journal of polymer science. Part A, Polymer chemistry》2003,41(1):22-29
A soluble aromatic polyimide was chloromethylated via a reaction with chloromethyl methyl ether in the presence of tin(IV) chloride to produce a new starting material for the modification of aromatic polyimides. The chemical structure of the resulting polymer was confirmed by 1H NMR and Fourier transform infrared spectroscopy. The maximum number of chloromethyl groups per repeat unit was 1.81. The chloromethylated polyimide was stable up to 250 °C and soluble in both chloroform and tetrahydrofuran. So that its utilization for further modification could be demonstrated, cinnamic acid was reacted with the formed polyimide, and it produced a new photosensitive polyimide with a cinnamoyl side chain. The photosensitivity of the resulting polyimide was investigated with ultraviolet spectroscopic methods. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 22–29, 2003 相似文献
7.
Seok‐Ho Hwang Kyung Soo Yoo Charles N. Moorefield Sang‐Won Lee George R. Newkome 《Journal of Polymer Science.Polymer Physics》2004,42(8):1487-1495
A series of metallodendrimers, assembled by means of bis(terpyridinyl)Ru(II) connectivity on poly(propylene imine) dendrimer scaffolds, with homogeneous or heterogeneous surfaces, were prepared. Differential scanning calorimetry and thermogravimetric analysis were used to determine their thermal behavior, glass‐transition temperatures, and the decomposition kinetics and temperatures; no synergy effects for these properties were observed for the heterogeneously surfaced constructs in contrast to the corresponding homogeneously coated materials, which exhibited different values depending on their surface functionalities. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1487–1495, 2004 相似文献
8.
We propose means for computing the Fourier expansions of periodic
functions appearing in higher moments of the sum-of-digits
function and in the solutions of some divide-and-conquer
recurrences. The expansions are shown to be absolutely
convergent. We also give a new approach to efficiently compute
numerically the coefficients involved to high precision. 相似文献
9.
Recently, the theory of sortability of partition property has been shown to be an effective tool to prove the existence of an optimal partition with that property. In this paper, we extend the theory to multi-partition where the partition is on t types of components. We apply our results to settle an optimal assignment problem whose proof was incomplete as given in the literature. 相似文献
10.
In this paper, we report that the phase transformation of Ni-B, Ni-P diffusion barriers deposited electrolessly on Cu, for the reason that the Ni-P layer is a more effective diffusion barrier than the Ni-B layer. The Ni3B crystallized was decomposed to Ni and B2O3 above 400 °C and the Ni3P crystallized was decomposed to Ni and P2O5 above 600 °C respectively in Ar atmosphere. Also, the Ni3B was decomposed to Ni and free B above 400 °C and the Ni3P was decomposed to Ni and free P above 600 °C respectively in H2 atmosphere. The decomposed Ni formed a solid solution with Cu. The Cu diffusion occurred above 400 °C for Ni-B layer and above 600 °C for Ni-P layer, respectively. Because the decomposition temperature of Ni-P layer is about 200 °C higher than that of Ni-B layer, the Ni-P layer is a more effective barrier for Cu than the Ni-B layer. 相似文献