全文获取类型
收费全文 | 3821篇 |
免费 | 312篇 |
国内免费 | 121篇 |
专业分类
化学 | 4114篇 |
晶体学 | 6篇 |
力学 | 10篇 |
综合类 | 2篇 |
数学 | 4篇 |
物理学 | 118篇 |
出版年
2023年 | 11篇 |
2022年 | 14篇 |
2021年 | 34篇 |
2020年 | 68篇 |
2019年 | 44篇 |
2018年 | 63篇 |
2017年 | 135篇 |
2016年 | 176篇 |
2015年 | 164篇 |
2014年 | 151篇 |
2013年 | 353篇 |
2012年 | 165篇 |
2011年 | 228篇 |
2010年 | 244篇 |
2009年 | 248篇 |
2008年 | 249篇 |
2007年 | 277篇 |
2006年 | 252篇 |
2005年 | 237篇 |
2004年 | 235篇 |
2003年 | 174篇 |
2002年 | 144篇 |
2001年 | 79篇 |
2000年 | 75篇 |
1999年 | 60篇 |
1998年 | 55篇 |
1997年 | 47篇 |
1996年 | 43篇 |
1995年 | 44篇 |
1994年 | 45篇 |
1993年 | 46篇 |
1992年 | 44篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有4254条查询结果,搜索用时 31 毫秒
941.
I. I. Tverdokhlebova I. A. Ronova V. M. Men'shov N. V. Pertsova 《Russian Chemical Bulletin》1998,47(12):2348-2351
Molecular-weight parameters of new silane homo- and copolymers were analyzed. For all polymers, theM
w values are close ((6.0–8.6)·104), the curves of molecular weight distribution are unimodal, andM
w/M
n=2−2.5. Cyclic fragments or those containing the −C=C− groups make the major contribution to the polysilane chain rigidity.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2430–2433, December, 1998. 相似文献
942.
Steve Granick Sanat K. Kumar Eric J. Amis Markus Antonietti Anna C. Balazs Arup K. Chakraborty Gary S. Grest Craig Hawker Paul Janmey Edward J. Kramer Ralph Nuzzo Thomas P. Russell Cyrus R. Safinya 《Journal of Polymer Science.Polymer Physics》2003,41(22):2755-2793
A comprehensive review of ongoing and recommended research directions concerning the structure, dynamics, and interfacial activity of synthetic and naturally occurring macromolecules at the solid–liquid interface is presented. Many new developments stem from the ability to target new size regimes of 1–100 nm. These rapid developments are reviewed critically with respect to chemical synthesis, processing, structural characterization, dynamic processes, and theoretical and computational analysis. The common problems shared by flat and particulate surfaces are emphasized. A broad spectrum of material properties are discussed, from the control of interfacial friction between surfaces in moving contact, to the mechanical strength and durability of the interfaces in hybrid materials, to optical and electronic properties. Future research opportunities are identified that involve (1) the emergence of nanoscale material properties, (2) polymer‐assisted nanostructures, and (3) the crossroads between interfacial science and biological and bioinspired applications. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2755–2793, 2003 相似文献
943.
A. G. Mirochnik N. V. Petrochenkova V. E. Karasev I. A. Borisov A. P. Kulikov T. Nakajima 《Russian Chemical Bulletin》1994,43(5):904-905
The luminescence and photochemical properties of EuIII complexes with copolymers of acrylic acid and butyl methacrylate have been studied by luminescence, IR spectroscopy, and EXAFS.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 958–959, May, 1994. 相似文献
944.
苯乙烯-p-乙烯基苯甲酸两亲性嵌段共聚物在乙醇中自组装行为的电镜观察 总被引:2,自引:6,他引:2
两亲性嵌段共聚物在只对其中一链段为良溶剂的选择性溶剂中 ,能够自组装形成胶束 .胶束的形态和尺寸大小依赖于两链段的性质 ,共聚物的组成、浓度、溶剂的性质等[1] .这一性质使得嵌段共聚物在分子识别、药物和其他物质的输送、基因疗法、水系涂料、污染物的除去、纳米复合材料的制备、催化剂以及传感器等方面展示着潜在的应用前景 .因此 ,两亲性嵌段共聚物的合成及其在选择性溶剂中的自组装行为的研究近年来颇受关注[2 ] .依据两链段的比例不同 ,嵌段共聚物可形成星状胶束和“板寸头”(Crew cut)型胶束[3 ] .当可溶段远比不溶段长时… 相似文献
945.
Guojun Liu Department of Chemistry University of Calgary University Dr. NW Calgary Alberta Canada TN IN 《高分子科学》2000,(3):255-262
Nanostructure fabrication from block copolymers in my group normally involves polymer design, synthesis, self-assembly, selective domain crosslinking, and sometimes selective domain removal. Preparation of thin films withnanochannels was used to illustrate the strategy we took. In this particular case, a linear triblock copolymer polyisoprenc-block-poly(2-cinnamoylethyl methacrylate)-block-poly(t-butyl acrylate), PI-b-PCEMA-b-PtBA, was used. Films, 25 to50 μm thick, were prepared from casting on glass slides a toluene solution of PI-b-PCEMA-b-PtBA and PtBA homopolymer,hPtBA, where hPtBA is shorter than the PtBA block. At the hPtBA mass faction of 20% relative to the triblock or the totalPtBA (hPtBA and PtBA block) volume fraction of 0.44, hPtBA and PtBA formed a seemingly continuous phase in the matrixof PCEMA and Pl. Such a block segregation pattern was locked in by photocrosslinking the PCEMA domain. Nanochannelswere formed by extracting out hPtBA with solvent. Alternatively. larger channels were obtained from extracting out hPtBAand hydrolyzing the t-butyl groups of the PtBA block. Such membranes were not liquid permeable but had gas permeabilityconstants ~6 orders of magnitude higher than that of low-density polyethylene films. 相似文献
946.
947.
研究了几种新型含有机硅二元和三元多嵌段共聚物的氧、氮选择透过性能。其中双酚A聚羟基醚-聚二甲基硅氧烷二元多嵌段共聚物-(PHE-PDMS)_n的透氧系数Po_2=510Barrer、氧氮分离系数a o_2/N_2=2.2,聚苯醚-聚二甲基硅氧烷-聚对羟基苯乙烯三元多嵌段共聚物-(PPO-PDMS-pHS)_n的Po_2=156 Barrer、do_2/N_2=2.4,两者都具有良好的力学性能。此外,含有机硅三元多嵌段共聚物与聚三甲硅基丙炔(PTMSP)起薄复合后,改善了PTMSP超薄膜的透气稳定性。其JO_2≈1.0×10~(-3)cm~2/cm~2·s·cmHg,do_2/N_2≥2.0。 相似文献
948.
A chloromethylated styrene-divinylbenzene copolymer support system functionalized with 4-benzaldehyde and 2-benzaldehyde was prepared.The degree of functionalization with aldehyde groups is well suited for the subsequent use of the products as Wittig reagents.The polymer bound aldehyde was reacted with Wittig reagents to give olefin groups grafted on styrene-divinylbenzene copolymers.The reactions were carried out in phase transfer catalysis conditions.A simple procedure for the calculation of the degree of functionalization and the statistical modeling of the structural repetitive unit of the copolymer are reported. 相似文献
949.
950.