全文获取类型
收费全文 | 166篇 |
免费 | 1篇 |
专业分类
化学 | 91篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 41篇 |
物理学 | 32篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 10篇 |
2012年 | 15篇 |
2011年 | 8篇 |
2010年 | 2篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有167条查询结果,搜索用时 46 毫秒
131.
Philip J. Cox Yanhui Meng Satyajit D. Sarker Qinying Deng Guo Xu 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):e516-e517
The relative stereochemistry of ternifoline‐C (7,20‐epoxy‐ent‐kaur‐16‐ene‐1,6,7,15‐tetrol 1‐acetate), C22H32O6, previously reported by Wu [FudanXuebaoZir. Kex. (1988), 27 , 61–65], has been redetermined at 150 K. The molecular geometry and crystal packing agree well with the previous study. 相似文献
132.
Prodip Sarker John R. Ebdon Stephen Rimmer 《Macromolecular rapid communications》2006,27(23):2007-2013
Summary: Radical copolymerization of 1,1‐bis(ethoxycarbonyl)‐2‐vinylcyclopropane (ECVCP) with allyl carbonates that contain isopropyl groups yields highly branched polyvinylcyclopropanes. The polymerizations were carried out in the presence of 2,2‐azoisobutyronitrile at 150 °C in chlorobenzene. Structural analysis of the polymers suggested that radical ring‐opening polymerization proceeded through 1,5‐ring‐opening followed by transfer to the allylic carbonate comonomers. Intra‐molecular cyclization, which yields polycyclobutane units, was also observed during the polymerization.
133.
Habibur Rahman Hazrat Ali Rafi Ud Din Iftikhar Ahmad Mahidur R. Sarker Sawal Hamid Md Ali 《Molecules (Basel, Switzerland)》2021,26(21)
Surface plasmon (SP)—induced spectral hole burning (SHB) at the silver-dielectric interface is investigated theoretically. We notice a typical lamb dip at a selective frequency, which abruptly reduces the absorption spectrum of the surface plasmons polaritons (SPP). Introducing the spontaneous generated coherence (SGC) in the atomic medium, the slope of dispersion becomes normal. Additionally, slow SPP propagation is also noticed at the interface. The spectral hole burning dip is enhanced with the SGC effect and can be modified and controlled with the frequency and intensity of the driving fields. The SPP propagation length at the hole-burning region is greatly enhanced under the effect of SGC. A propagation length of the order of 600 µm is achieved for the modes, which is a remarkable result. The enhancement of plasmon hole burning under SGC will find significant applications in sensing technology, optical communication, optical tweezers and nano-photonics. 相似文献
134.
Md. Nazmul Hossain Umakanta Sarker Md. Sharif Raihan Asma A. Al-Huqail Manzer H. Siddiqui Shinya Oba 《Molecules (Basel, Switzerland)》2022,27(6)
This is the first attempt to evaluate the impact of four salinity levels on the color parameters, pigments, polyphenols, flavonoids, and antioxidant capacities of four promising A. lividus genotypes. The color parameters, such as the yellowness/blueness (b*) and the chroma (C*); the antioxidant components, such as the polyphenols and flavonoids; and the antioxidant capacities of the leaves were remarkably increased by 39, 1, 5, 10 and 43%, respectively, at 50 mM of NaCl, and by 55, 5, 60, 34, 58 and 82%, respectively, at 100 mM NaCl concentrations. The green tower and SA6 genotypes were identified as tolerant varieties. The total phenolic content (TPC) and the total flavonoid content (TFC) played vital roles in scavenging reactive oxygen species (ROS), and they would be beneficial for the human diet and would serve as good antioxidants for the prevention of aging, and they are also essential to human health. A correlation study revealed the strong antioxidant capacities of the pigments and antioxidant components that were studied. It was revealed that A. lividus could tolerate a certain level of salinity stress without compromising the antioxidant quality of the final product. Taken together, our results suggest that A. lividus could be a promising alternative crop for farmers, especially in saline-prone areas in the tropical and subtropical regions. 相似文献
135.
Ananda M. Sarker Alexander Y. Polykarpov Anita M. De Raaff Thomas L. Marino D. C. Neckers 《Journal of polymer science. Part A, Polymer chemistry》1996,34(13):2817-2824
Several new tetraorganylborate salts have been synthesized and tested as coinitiators with 2,4-diiodo-6-butoxy-3-fluorone (DIBF) for the photopolymerization of acrylic monomer mixtures. The rate of photopolymerization has been found to be a function of chemical structure of the borates. Stability, solubility, and reactivity of these borates as coinitiators for photopolymerization have been investigated. Diphenyldialkylborates have been found to be the best among the tested coinitiators. © 1996 John Wiley & Sons, Inc. 相似文献
136.
137.
Jacob D. Teeter Dr. Paulo S. Costa Christoph Dobner Mamun Sarker Prof. Dr. Alexander Sinitskii Prof. Dr. Axel Enders 《Chemphyschem》2021,22(17):1769-1773
The on-surface coupling of the prototypical precursor molecule for graphene nanoribbon synthesis, 6,11-dibromo-1,2,3,4-tetraphenyltriphenylene (C42Br2H26, TPTP), and its non-brominated analog hexaphenylbenzene (C42H30, HPB), was investigated on coinage metal substrates as a function of thermal treatment. For HPB, which forms non-covalent 2D monolayers at room temperature, a thermally induced transition of the monolayer's structure could be achieved by moderate annealing, which is likely driven by π-bond formation. It is found that the dibrominated carbon positions of TPTP do not guide the coupling if the growth occurs on a substrate at temperatures that are sufficient to initiate C−H bond activation. Instead, similar one-dimensional molecular structures are obtained for both types of precursors, HPB and TPTP. 相似文献
138.
I. V. Amirkhanov A. Yu. Didyk N. R. Sarker I. Sarhadov V. K. Semina A. Hofman Z. A. Sharipov 《Physics of Particles and Nuclei Letters》2006,3(5):320-326
A thermal spike model in a three-dimensional case is used for the calculation of temperatures in a structure consisting of two layers of different materials. The systems of equations for electron gas and lattice temperatures are solved numerically in the axial-symmetric coordinate system at constant values of specific capacities and thermal conductivities for the Ni(2 μm)/W two-layer system. One can conclude on the basis of the obtained results that the phase transitions can take place when there is irradiation of the Ni(2 μm)/W two-layer structure with 209Bi ions with an energy of 710 MeV: melting, in both layers; and evaporation, only in the Ni layer (first layer). The maximum radii and depths where the melting (Ni and W layers) and evaporation (Ni layer) processes occur are calculated. 相似文献
139.
A detailed theoretical analysis is presented to evaluate the combined influence of self-phase modulation (SPM) and group velocity dispersion (GVD) of optical fiber on the bit error rate (BER) performance of a heterodyne optical CPFSK system. The power penalty suffered by the system due to the combined influence of GVD and SPM is evaluated from the BER performance results. It is found that the penalty due to SPM at a BER of 10−9 is significant when the input power exceeds 7 dBm. Further, the CPFSK system with modulation index of 0.5 is less sensitive to the effects of GVD and SPM compared to the system with a modulation index of 1. The theoretical results are in conformity with the experimental results reported earlier. 相似文献
140.
The broadening of analyte streams, as they migrate through a free-flow electrophoresis (FFE) channel, often limits the resolving power of FFE separations. Under laminar flow conditions, such zonal spreading occurs due to analyte diffusion perpendicular to the direction of streamflow and variations in the lateral distance electrokinetically migrated by the analyte molecules. Although some of the factors that give rise to these contributions are inherent to the FFE method, others originate from non-idealities in the system, such as Joule heating, pressure-driven crossflows, and a difference between the electrical conductivities of the sample stream and background electrolyte. The injection process can further increase the stream width in FFE separations but normally influencing all analyte zones to an equal extent. Recently, several experimental and theoretical works have been reported that thoroughly investigate the various contributions to stream variance in an FFE device for better understanding, and potentially minimizing their magnitudes. In this review article, we carefully examine the findings from these studies and discuss areas in which more work is needed to advance our comprehension of the zone broadening contributions in FFE assays. 相似文献