全文获取类型
收费全文 | 1073篇 |
免费 | 37篇 |
国内免费 | 4篇 |
专业分类
化学 | 556篇 |
晶体学 | 11篇 |
力学 | 37篇 |
数学 | 71篇 |
物理学 | 439篇 |
出版年
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 12篇 |
2020年 | 25篇 |
2019年 | 32篇 |
2018年 | 33篇 |
2017年 | 18篇 |
2016年 | 34篇 |
2015年 | 26篇 |
2014年 | 38篇 |
2013年 | 113篇 |
2012年 | 75篇 |
2011年 | 77篇 |
2010年 | 48篇 |
2009年 | 49篇 |
2008年 | 54篇 |
2007年 | 58篇 |
2006年 | 38篇 |
2005年 | 39篇 |
2004年 | 18篇 |
2003年 | 17篇 |
2002年 | 26篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 18篇 |
1995年 | 18篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1938年 | 2篇 |
排序方式: 共有1114条查询结果,搜索用时 156 毫秒
51.
52.
53.
Gakhyun Kim Dr. Ranjan Dutta Dr. Won-Young Cha Dr. Seong-Jin Hong Dr. Juwon Oh Dr. Dikhi Firmansyah Hongil Jo Prof. Dr. Kang Min Ok Prof. Dr. Chang-Hee Lee Prof. Dr. Dongho Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(69):16434-16440
π–π Stacking is omnipresent not only in nature but in a wide variety of practical fields applied to our lives. Because of its importance in a performance of natural and artificial systems, such as light harvesting system and working layer in device, many researchers have put intensive effort into identifying its underlying nature. However, for the case of π–π stacked systems composed of antiaromatic units, the understanding of the fundamental mechanisms is still unclear. Herein, we synthesized a new type of planar β,β’-phenylene-bridged hexaphyrin (1.0.1.0.1.0), referred as naphthorosarin which possesses the 24π-electron conjugated pathway. Especially, the corresponding antiaromatic porphyrinoid shows the unique property to form dimeric species adopting the face-to-face geometry which is unprecedented in cases of known annulated naphthorosarins. In order to elucidate the intriguing properties derived from the stacked dimer, the current study focuses on the experimental support to rationalize the observed π–π interactions between the two subunits. 相似文献
54.
Dr. Chandan Kumar Karan Sourav Mallick Prof. Dr. C. Retna Raj Prof. Dr. Manish Bhattacharjee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(65):14775-14779
A zinc containing metal–organic gel (Zn-MOG) with embedded free ions, which exhibits self-healing properties, has been synthesized for application in supercapacitors. The activated carbon-based flexible supercapacitor device with the MOG electrolyte has a broad potential window of 2.1 V, with high retention of specific capacitance compared to the traditional polyvinyl alcohol (PVA)-based gel. The Zn-MOG does not require an additional electrolyte. The sodium and sulphate ions embedded in the MOG are sufficient enough for the charge storage. 相似文献
55.
This communication reports the successful adsorption of a water-soluble cationic fluorescent dye Acridine Orange (AO) onto Langmuir–Blodgett (LB) films of a cationic amphiphile octadecylamine (ODA) in the presence of nano-clay platelets hectorite. Acridine orange (AO) has been widely used as a stainer for the characterization of biopolymers. But AO has a tendency to form non-florescent H-dimer even in the aqueous solution. Anionic nano-clay platelets hectorite played an important role in controlling the H-dimer formation of AO in the hybrid film. Effects of various parameters in the adsorption process were investigated in detail. 相似文献
56.
Ranjan Maitra 《Journal of computational and graphical statistics》2013,22(1):132-142
Abstract Functional imaging of biologic parameters like in vivo tissue metabolism is made possible by Positron Emission Tomography (PET). Many techniques have been suggested for extracting such images from dynamic time-course sequences of reconstructed PET scans. Quantitating the precision of these estimates is important for drawing inferences on the biologic parameters. Analytic variance formulas are not immediate owing to the nonlinear methods used in extraction. The usual resampling approach is infeasible because each image reconstruction in PET is a computationally demanding solution to a high-dimensional linear inverse problem. We suggest an alternative simulation approach that approximates the distribution of reconstructed PET scans and performs a parametric bootstrap in the imaging domain. Results on a simplified model chosen to match the characteristics of PET reconstruction are very encouraging. Mixture analysis is used to estimate functional images; however, the suggested approach is general enough to extend to other techniques or imaging methods. 相似文献
57.
58.
Synthesis and in vitro antimicrobial screening of new pyrano[4,3-b]pyrane derivatives of 1H-pyrazole
A new series of pyrano[4,3-b]pyrane 4a-l bearing 1H-pyrazole has been synthesized by one pot base catalyzed cyclocondensation reaction of 1H-pyrazole-4-carbaldehyde la-1,malononitrile 2 and 4-hydroxy-6-methylpyrone 3.All the synthesized compounds were screened against six bacterial pathogens,namely B.subtilis,C.tetani,S.pneumoniae,S.typhi,V.cholerae, E.coli and antifungal activity against,two fungal pathogens,A.fumigatus and C.albicans using broth microdilution MIC method. Some of the compounds are found to be equipotent or more potent than that of commercial drugs,against most of employed strains. 相似文献
59.
60.