全文获取类型
收费全文 | 7073篇 |
免费 | 1396篇 |
国内免费 | 1145篇 |
专业分类
化学 | 5432篇 |
晶体学 | 108篇 |
力学 | 380篇 |
综合类 | 94篇 |
数学 | 901篇 |
物理学 | 2699篇 |
出版年
2024年 | 15篇 |
2023年 | 143篇 |
2022年 | 188篇 |
2021年 | 261篇 |
2020年 | 319篇 |
2019年 | 314篇 |
2018年 | 290篇 |
2017年 | 275篇 |
2016年 | 342篇 |
2015年 | 410篇 |
2014年 | 441篇 |
2013年 | 505篇 |
2012年 | 659篇 |
2011年 | 741篇 |
2010年 | 536篇 |
2009年 | 429篇 |
2008年 | 531篇 |
2007年 | 465篇 |
2006年 | 395篇 |
2005年 | 343篇 |
2004年 | 281篇 |
2003年 | 280篇 |
2002年 | 346篇 |
2001年 | 251篇 |
2000年 | 143篇 |
1999年 | 134篇 |
1998年 | 86篇 |
1997年 | 64篇 |
1996年 | 72篇 |
1995年 | 71篇 |
1994年 | 53篇 |
1993年 | 36篇 |
1992年 | 38篇 |
1991年 | 33篇 |
1990年 | 39篇 |
1989年 | 22篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有9614条查询结果,搜索用时 15 毫秒
61.
We developed a novel method to assemble TiO2 nanorods conjugated with CdS quantum dots by L-cysteine molecular linker for type II semiconducting hybrid structure. The XRD patterns indicate that the CdS quantum dots perform the cubic phase structure, and TEM images show that CdS quantum dots are well dispersed on the surfaces of anatase TiO2 nanorods with little agglomeration. The UV-vis absorption spectra reveal the bandgap alignment in type II configuration between CdS QDs and TiO2 nanorods. 相似文献
62.
Jun‐Yi Chen Zi‐Long Xiang Feng Yu Bert F. Sels Yu Fu Ting Sun Mario Smet Wim Dehaen 《Journal of polymer science. Part A, Polymer chemistry》2014,52(18):2596-2603
A series of hyperbranched polyacenaphthenequinones has been prepared by superelectrophilic aromatic substitution of (substituted) acenaphthenequinone and 1,3,5‐tris‐(4‐phenoxybenzoyl)benzene via a facile A2 + B3 approach. Because of the strongly increased reactivity of the second A functionality, gelation was efficiently avoided during the polymerization. The structure of the resulting polymer was characterized by NMR spectroscopy and gel permeation chromatography. Further modification of the hyperbranched polyacenaphthenequinone was explored both on the acenaphthenequinone and aromatic moieties. Moreover, the polymer modified through sulfonation was investigated as a water‐soluble acid catalyst for the degradation of biomass resources. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2596‐2603 相似文献
63.
This study investigated the possibility of substituting petroleum-based polymers with biopolymers for films and paper coatings. Arabinoxylan (AX) was extracted from distillers’ grains, a low-value corn ethanol byproduct, and modified through crosslinking with glutaraldehyde (GA) which was made into films and paper coatings. The effects of degree of substitution (DS) on film and coating properties of GA cross-linked AX, referred to as GAX, were investigated. The GAX films had markedly higher tensile strength, approximately 3 times higher than the unmodified AX films at low DS, with higher DS causing a negative effect on the film tensile strength. Compared to unmodified AX coating, paper coated with GAX also had significantly higher tensile index, presumably due to high adhesion between the coating and paper interface. When used as a coating binder with calcium carbonate pigments, GAX showed comparable performance to polyvinyl alcohol, a common industrial binder, demonstrating the potential to be substituted for the petroleum-based paper coating binder. 相似文献
64.
65.
Xiang Li Prof. Dr. Hong Yan Prof. Dr. Qiang Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):1888-1898
Phosphorescent transition‐metal complexes (PTMCs) have attracted great interest because of their excellent properties which may lead to promising applications in optoelectronics. In recent years, carboranes have been demonstrated to be a novel and effective tool to tune phosphorescence of PTMCs. This Concept article deals with the advances of carborane‐functionalized PTMCs for potential optical applications. The discussions are focused on the design strategies and synthetic procedures leading to carborane‐functionalized PTMCs, the influence of carboranes on the optical properties of PTMCs, and the promising optical applications of this interesting class of phosphorescent materials. 相似文献
66.
One‐Pot Tandem Diastereoselective and Enantioselective Synthesis of Functionalized Oxindole‐Fused Spiropyrazolidine Frameworks 下载免费PDF全文
Liang‐Yong Mei Dr. Xiang‐Ying Tang Prof. Dr. Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13136-13142
A highly efficient palladium(0)‐catalyzed asymmetric [3+2] cycloaddition using 3‐diazooxindoles serving as dipolarophiles affords functionalized pyrazolidine derivatives in an atom‐economical way. In addition, by trapping the pyrazolidine derivatives with maleimides, the corresponding spiropyrazolidine oxindoles containing multiple stereogenic centers have been obtained in high yields along with moderate to good levels of diastereoselectivity and enantioselectivity under mild conditions. Thus, a novel three‐component one‐pot tandem reaction has been developed. 相似文献
67.
68.
Size controlled synthesis of ornithine‐based polypeptides by ring‐opening polymerization of α‐(amino acid)‐N‐carboxyanhydrides 下载免费PDF全文
69.
Light‐Driven Reversible Alignment Switching of Liquid Crystals Enabled by Azo Thiol Grafted Gold Nanoparticles 下载免费PDF全文
Dr. Chenming Xue Jie Xiang Hossein Nemati Dr. Hari Krishna Bisoyi Karla Gutierrez‐Cuevas Dr. Ling Wang Dr. Min Gao Shuang Zhou Prof. Deng‐ke Yang Prof. Oleg D. Lavrentovich Dr. Augustine Urbas Prof. Quan Li 《Chemphyschem》2015,16(9):1852-1856
Stimuli‐directed alignment control of liquid crystals (LCs) with desired molecular orientation is currently in the limelight for the development of smart functional materials and devices. Here, photoresponsive azo thiol (AzoSH) was grafted onto gold nanoparticles (GNPs). The resulting hybrid GNPs were able to homogeneously mix with a commercially available nematic LC host, as evidenced by Cryo‐TEM. Interestingly, the LC nanocomposites were found to undergo reversible alignment transition upon light irradiation as a consequence of the trans–cis photoisomerization of the azo groups on the GNP surface. LC molecules in either planar or bare glass cells were able to change their alignment to vertical upon UV irradiation, while the vertically aligned LC molecules returned to the planar or random orientation under visible irradiation. Neither the azo thiol molecules nor the unfunctionalized GNPs alone promoted the alignment of the LC molecules in the system upon light irradiation. The photoinduced vertical alignment without applied electric or magnetic field was very stable over time and with respect to temperature. Furthermore, an optically switchable device based on the photostimulated reversible alignment control of LCs was demonstrated. 相似文献
70.
Prof. Dr. Suning Wang Deng‐Tao Yang Jiasheng Lu Hiroyuki Shimogawa Prof. Dr. Shaolong Gong Xiang Wang Soren K. Mellerup Prof. Dr. Atsushi Wakamiya Dr. Yi‐Lu Chang Prof. Dr. Chuluo Yang Prof. Dr. Zheng‐Hong Lu 《Angewandte Chemie (International ed. in English)》2015,54(50):15074-15078
New BN‐heterocyclic compounds have been found to undergo double arene photoelimination, forming rare yellow fluorescent BN‐pyrenes that contain two B? N units. Most significant is the discovery that the double arene elimination can also be driven by excitons generated electrically within electroluminescent (EL) devices, enabling the in situ solid‐state conversion of BN‐heterocycles to BN‐pyrenes and the use of BN‐pyrenes as emitters for EL devices. The in situ exciton‐driven elimination (EDE) phenomenon has also been observed for other BN‐heterocycles. 相似文献