全文获取类型
收费全文 | 8260篇 |
免费 | 254篇 |
国内免费 | 62篇 |
专业分类
化学 | 5543篇 |
晶体学 | 78篇 |
力学 | 247篇 |
综合类 | 1篇 |
数学 | 1307篇 |
物理学 | 1400篇 |
出版年
2023年 | 42篇 |
2021年 | 75篇 |
2020年 | 155篇 |
2019年 | 112篇 |
2018年 | 84篇 |
2017年 | 94篇 |
2016年 | 186篇 |
2015年 | 151篇 |
2014年 | 194篇 |
2013年 | 395篇 |
2012年 | 456篇 |
2011年 | 556篇 |
2010年 | 281篇 |
2009年 | 223篇 |
2008年 | 493篇 |
2007年 | 456篇 |
2006年 | 443篇 |
2005年 | 447篇 |
2004年 | 424篇 |
2003年 | 282篇 |
2002年 | 268篇 |
2001年 | 75篇 |
2000年 | 63篇 |
1999年 | 48篇 |
1998年 | 58篇 |
1997年 | 82篇 |
1996年 | 124篇 |
1995年 | 77篇 |
1994年 | 63篇 |
1993年 | 88篇 |
1992年 | 62篇 |
1991年 | 73篇 |
1990年 | 71篇 |
1989年 | 58篇 |
1988年 | 69篇 |
1987年 | 61篇 |
1986年 | 51篇 |
1985年 | 113篇 |
1984年 | 128篇 |
1983年 | 89篇 |
1982年 | 112篇 |
1981年 | 108篇 |
1980年 | 88篇 |
1979年 | 82篇 |
1978年 | 108篇 |
1977年 | 93篇 |
1976年 | 80篇 |
1975年 | 67篇 |
1974年 | 67篇 |
1973年 | 58篇 |
排序方式: 共有8576条查询结果,搜索用时 31 毫秒
1.
Dr. Mara Beltrán-Gastélum Dr. Berta Esteban-Fernández de Ávila Dr. Hua Gong Dr. Pooyath Lekshmy Venugopalan Prof. Dr. Tibor Hianik Prof. Dr. Joseph Wang Veronika Subjakova 《Chemphyschem》2019,20(23):3177-3180
Herein, we report ultrasound-propelled graphene-oxide coated gold nanowire motors, functionalized with fluorescein-labeled DNA aptamers (FAM-AIB1-apt), for qualitative detection of overexpressed AIB1 oncoproteins in MCF-7 breast cancer cells. The movement of nanomotors under the ultrasound field facilitated intracellular uptake and resulted in a faster aptamer binding with the target protein and thus faster fluorescence recovery. The propulsion behavior of the aptamer functionalized nanomotors greatly enhanced the fluorescence intensity compared to static conditions. The new aptamer@nanomotor-based strategy offers considerable potential for further development of sensing methodologies towards diagnosis of breast cancer. 相似文献
2.
3.
Yifeng Xiang Xi Tang Changjun Min Guanghao Rui Yan Kuai Fengya Lu Pei Wang Hai Ming Qiwen Zhan Xiaocong Yuan Joseph R. Lakowicz Douguo Zhang 《Annalen der Physik》2020,532(4):1900497
Near-field optical trapping can be realized with focused evanescent waves that are excited at the water–glass interface due to the total internal reflection, or with focused plasmonic waves excited on the water–gold interface. Herein, the performance of these two kinds of near-field optical trapping techniques is compared using the same optical microscope configuration. Experimental results show that only a single-micron polystyrene bead can be trapped by the focused evanescent waves, whereas many beads are simultaneously attracted to the center of the excited region by focused plasmonic waves. This difference in trapping behavior is analyzed from the electric field intensity distributions of these two kinds of focused surface waves and the difference in trapping behavior is attributed to photothermal effects due to the light absorption by the gold film. 相似文献
4.
Optics and Spectroscopy - Scattering of light by disordered structures is normally detrimental to their applicability in many optoelectronic devices. However, some micro and nanostructures are... 相似文献
5.
Chase A. Salazar Joseph J. Gair Kaylin N. Flesch Ilia A. Guzei Jared C. Lewis Shannon S. Stahl 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(27):10965-10969
Mono-N-protected amino acids (MPAAs) are increasingly common ligands in Pd-catalyzed C−H functionalization reactions. Previous studies have shown how these ligands accelerate catalytic turnover by facilitating the C−H activation step. Here, it is shown that MPAA ligands exhibit a second property commonly associated with ligand-accelerated catalysis: the ability to support catalytic turnover at substoichiometric ligand-to-metal ratios. This catalytic role of the MPAA ligand is characterized in stoichiometric C−H activation and catalytic C−H functionalization reactions. Palladacycle formation with substrates bearing carboxylate and pyridine directing groups exhibit a 50–100-fold increase in rate when only 0.05 equivalents of MPAA are present relative to PdII. These and other mechanistic data indicate that facile exchange between MPAAs and anionic ligands coordinated to PdII enables a single MPAA to support C−H activation at multiple PdII centers. 相似文献
6.
Pengjin Qin Li-An Wang Prof. Joseph M. O'Connor Prof. Kim K. Baldridge Yifan Li Burak Tufekci Jiyue Chen Prof. Arnold L. Rheingold 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18114-18121
Triene 6π electrocyclization, wherein a conjugated triene undergoes a concerted stereospecific cycloisomerization to a cyclohexadiene, is a reaction of great historical and practical significance. In order to circumvent limitations imposed by the normally harsh reaction conditions, chemists have long sought to develop catalytic variants based upon the activating power of metal–alkene coordination. Herein, we demonstrate the first successful implementation of such a strategy by utilizing [(C5H5)Ru(NCMe)3]PF6 as a precatalyst for the disrotatory 6π electrocyclization of highly substituted trienes that are resistant to thermal cyclization. Mechanistic and computational studies implicate hexahapto transition-metal coordination as responsible for lowering the energetic barrier to ring closure. This work establishes a foundation for the development of new catalysts for stereoselective electrocyclizations. 相似文献
7.
XPS and resistive studies on thin films of a copper(II)‐based coordination polymer deposited on functionalized interdigital electrodes 下载免费PDF全文
Michael Günthel Jörg Hübscher Rosemarie Dittrich Edwin Weber Yvonne Joseph Florian Mertens 《Journal of Polymer Science.Polymer Physics》2015,53(5):335-344
A symmetrical 2‐thiopyrimidine based molecule with an expanded π‐electron system is synthesized and used to form a self‐assembled monolayer (SAM) on gold surfaces. Utilizing chemical vapor deposition a monolayer of (3‐mercaptopropyl)triethoxysilane is formed on silicon dioxide substrates. Both of these SAM coated substrates are characterized by X‐ray photoelectron spectroscopy and the growth of a coordination polymer built up from 5,5′‐(ethyne‐1,2‐diyl)bis(2‐hydroxyacetophenone) and copper(II) on dual SAM coated transducers is studied. After the deposition procedure on interdigital electrodes the electrical properties of the polymer are investigated performing resistive measurements. A significant change of the resistance, which depends on the surrounding atmosphere, proves the sensing behavior of the synthesized coordination polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 335–344 相似文献
8.
9.
In this paper, we investigate the evolution of joint invariants under invariant geometric flows using the theory of equivariant moving frames and the induced invariant discrete variational complex. For certain arc length preserving planar curve flows invariant under the special Euclidean group , the special linear group , and the semidirect group , we find that the induced evolution of the discrete curvature satisfies the differential‐difference mKdV, KdV, and Burgers' equations, respectively. These three equations are completely integrable, and we show that a recursion operator can be constructed by precomposing the characteristic operator of the curvature by a certain invariant difference operator. Finally, we derive the constraint for the integrability of the discrete curvature evolution to lift to the evolution of the discrete curve itself. 相似文献