全文获取类型
收费全文 | 384篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 272篇 |
晶体学 | 2篇 |
力学 | 5篇 |
数学 | 21篇 |
物理学 | 87篇 |
出版年
2023年 | 3篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 17篇 |
2012年 | 14篇 |
2011年 | 18篇 |
2010年 | 14篇 |
2009年 | 6篇 |
2008年 | 17篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 16篇 |
2004年 | 13篇 |
2003年 | 12篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1986年 | 4篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1975年 | 8篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1969年 | 4篇 |
1966年 | 2篇 |
1965年 | 3篇 |
1963年 | 2篇 |
1961年 | 1篇 |
排序方式: 共有387条查询结果,搜索用时 18 毫秒
101.
Transport processes in plasticized PVC membranes containing the H+ chromoionophore ETH 5294 and additional tetraphenylborate-type mobile sites were analyzed by employing the potential-step method. Using chronoamperometry, impedance spectroscopy, and UV/VIS absorbance measurements, it is shown that the ionophore behaves as a carrier for protons, when the membranes are immersed between two aqueous solutions. It was possible to document the changes in the concentration profiles of both free ionophores and ionic species in some of the membranes. There is no evidence of proton hopping between the ionophores. 相似文献
102.
Buck BA Mascioni A Cramer CJ Veglia G 《Journal of the American Chemical Society》2004,126(44):14400-14410
Organotin compounds specifically target vicinal dithiols, thereby inhibiting the function of essential enzymes. Here, we present the NMR binding studies of trimethyltin (TMT) and dimethyltin (DMT) chlorides with a linear peptide (ILGCWCYLR) derived from the membrane protein stannin (SNN). We show that this peptide is able to dealkylate TMT and bind DMT, adopting a stable type-I beta-turn conformation. Both the NMR data and the calculated structures indicate that the two cysteines coordinate the tin atom in a distorted tetrahedral geometry. The molecular geometries and tin coordination state were confirmed using density functional theory (DFT). In addition, NMR spectral parameters back calculated from the DFT minimized structure compared well with experimental data. These results in conjunction with studies on peptide variants (i.e., C4S, C6S, and Y7F) demonstrate unequivocally the key role of biological dithiols in both the dealkylation and binding of organotin compounds. This peptide serves as a model system for alkyltin-protein interactions and gives new insights into the biological fate of alkyltin compounds. 相似文献
103.
104.
105.
The Zakai form of nonlinear prediction theory is used to estimate yearto-year state changes in crown-of-thorns starfish populations of the Great Barrier Reef. Taking the previously defined coral-state diffusion as observation process and the starfish-state diffusion as signal process, a least squares polynomial regression curve recently derived for simultaneously collected starfish/coral state data is used to set up the prediction preliminaries, Numerical results are not inconsistant with starfish outbreak values of the last 5 years and yield an expected high value for 1987. However, because of large error in the data it is doubtful that a more refined mesh for the Mihlstein approximations used to evaluate the Îto stochastic integrals involved in Zakai theory would improve the accuracy of predictions. 相似文献
106.
Synthesis and Characterization of Far‐Red/NIR‐Fluorescent BODIPY Dyes,Solid‐State Fluorescence,and Application as Fluorescent Tags Attached to Carbon Nano‐onions 下载免费PDF全文
Dr. Juergen Bartelmess Dr. Michele Baldrighi Dr. Valentina Nardone Dr. Emilio Parisini David Buck Prof. Dr. Luis Echegoyen Prof. Dr. Silvia Giordani 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9727-9732
A series of π‐extended distyryl‐substituted boron dipyrromethene (BODIPY) derivatives with intense far‐red/near‐infrared (NIR) fluorescence was synthesized and characterized, with a view to enhance the dye’s performance for fluorescence labeling. An enhanced brightness was achieved by the introduction of two methyl substituents in the meso positions on the phenyl group of the BODIPY molecule; these substituents resulted in increased structural rigidity. Solid‐state fluorescence was observed for one of the distyryl‐substituted BODIPY derivatives. The introduction of a terminal bromo substituent allows for the subsequent immobilization of the BODIPY fluorophore on the surface of carbon nano‐onions (CNOs), which leads to potential imaging agents for biological and biomedical applications. The far‐red/NIR‐fluorescent CNO nanoparticles were characterized by absorption, fluorescence, and Raman spectroscopies, as well as by thermogravimetric analysis, dynamic light scattering, high‐resolution transmission electron microscopy, and confocal microscopy. 相似文献
107.
Autumn M. Mineo Maren E. Buck Reika Katsumata 《Journal of polymer science. Part A, Polymer chemistry》2021,59(22):2719-2729
Polymer coatings are frequently used to modify surface properties of inorganic substrates. However, the disparity in physical properties between polymer film and substrate often leads to residual stress development, which can be deleterious to the overall performance of coated materials. This work reports the molecular design of polymer films that dissipate stress upon irradiation with ultraviolet (UV) light. These polymers are synthesized by post-polymerization modification of the reactive polymer, poly(2-vinyl-4,4-dimethyl azlactone), to introduce dynamic crosslinks capable of light-initiated addition transfer fragmentation chemistry. Using a custom-built optical cantilever, contrasting film stress responses are observed between films containing dynamic bonds and analogous control films after UV light irradiation, which indicate successful stress relaxation. Further experiments demonstrate the complete relaxation of residual stress in dynamic films after an extended exposure, thereby generating a “stress-free” film. Films fabricated using this approach can be easily tailored to incorporate additional moieties to introduce desired surface properties for future application in a wide array of coatings. 相似文献
108.
109.
A series of 3-substituted-3-chloro-2-propeniminium salts have been reacted with sodium borohydride and/or sodium cyanoborohydride to produce 1-substituted-1-chloro-3-N, N-dimethylamino-1-propenes in good yield. 相似文献
110.
Dewei Tang Jason R. Buck Matthew R. Hight H. Charles Manning 《Tetrahedron letters》2010,51(35):4595-4016
We herein report a dramatically improved total synthesis of the high-affinity translocator protein (TSPO) ligand DPA-714, featuring microwave-assisted organic synthesis (MAOS). Compared with previously described approaches, our novel MAOS method dramatically reduces overall reaction time without adversely effecting reaction yields. We envision that the described MAOS protocol may be suitably applied to high-throughput, diversity-oriented synthesis of novel compounds based on the pyrazolo-pyrimidinyl scaffold. Such an approach could accelerate the development of focused libraries of novel TSPO ligands with potential for future development as molecular imaging and therapeutic agents. 相似文献