全文获取类型
收费全文 | 1737篇 |
免费 | 241篇 |
国内免费 | 33篇 |
专业分类
化学 | 878篇 |
晶体学 | 5篇 |
力学 | 58篇 |
综合类 | 3篇 |
数学 | 29篇 |
物理学 | 1038篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 21篇 |
2021年 | 18篇 |
2020年 | 57篇 |
2019年 | 33篇 |
2018年 | 34篇 |
2017年 | 19篇 |
2016年 | 65篇 |
2015年 | 50篇 |
2014年 | 66篇 |
2013年 | 117篇 |
2012年 | 59篇 |
2011年 | 62篇 |
2010年 | 82篇 |
2009年 | 146篇 |
2008年 | 156篇 |
2007年 | 175篇 |
2006年 | 129篇 |
2005年 | 70篇 |
2004年 | 76篇 |
2003年 | 90篇 |
2002年 | 83篇 |
2001年 | 63篇 |
2000年 | 54篇 |
1999年 | 55篇 |
1998年 | 45篇 |
1997年 | 38篇 |
1996年 | 33篇 |
1995年 | 23篇 |
1994年 | 19篇 |
1993年 | 8篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有2011条查询结果,搜索用时 484 毫秒
991.
992.
Spatial and Directional Control over Self‐Assembly Using Catalytic Micropatterned Surfaces 下载免费PDF全文
Dr. Alexandre G. L. Olive Nor Hakimin Abdullah Dr. Iwona Ziemecka Dr. Eduardo Mendes Dr. Rienk Eelkema Prof. Dr. Jan H. van Esch 《Angewandte Chemie (International ed. in English)》2014,53(16):4132-4136
Catalyst‐assisted self‐assembly is widespread in nature to achieve spatial control over structure formation. Reported herein is the formation of hydrogel micropatterns on catalytic surfaces. Gelator precursors react on catalytic sites to form building blocks which can self‐assemble into nanofibers. The resulting structures preferentially grow where the catalyst is present. Not only is a first level of organization, allowing the construction of hydrogel micropatterns, achieved but a second level of organization is observed among fibers. Indeed, fibers grow with their main axis perpendicular to the substrate. This feature is directly linked to a unique mechanism of fiber formation for a synthetic system. Building blocks are added to fibers in a confined space at the solid–liquid interface. 相似文献
993.
Dr. Xiantao Shen Dr. Johan Svensson Bonde Tripta Kamra Prof. Leif Bülow Dr. Jack C. Leo Dr. Dirk Linke Dr. Lei Ye 《Angewandte Chemie (International ed. in English)》2014,53(40):10687-10690
The tendency of bacteria to assemble at oil–water interfaces can be utilized to create microbial recognition sites on the surface of polymer beads. In this work, two different groups of bacteria were first treated with acryloyl‐functionalized chitosan and then used to stabilize an oil‐in‐water emulsion composed of cross‐linking monomers that were dispersed in aqueous buffer. Polymerization of the oil phase followed by removal of the bacterial template resulted in well‐defined polymer beads bearing bacterial imprints. Chemical passivation of chitosan and cell displacement assays indicate that the bacterial recognition on the polymer beads was dependent on the nature of the pre‐polymer and the target bacteria. The functional materials for microbial recognition show great potential for constructing cell–cell communication networks, biosensors, and new platforms for testing antibiotic drugs. 相似文献
994.
Following the Azide‐Alkyne Cycloaddition at the Silica/Solvent Interface with Sum Frequency Generation 下载免费PDF全文
Zhiguo Li Dr. Champika N. Weeraman Prof. Julianne M. Gibbs‐Davis 《Chemphyschem》2014,15(11):2247-2251
The CuI‐catalyzed 1,3‐dipolar azide‐alkyne cycloaddition (CuAAC) has arisen as one of the most useful chemical transformations for introducing complexity onto surfaces and materials owing to its functional‐group tolerance and high yield. However, methods for monitoring such reactions in situ at the widely used silica/solvent interface are hampered by challenges associated with probing such buried interfaces. Using the surface‐specific technique broadband sum frequency generation (SFG), we monitored the reaction of a benzyl azide monolayer in real time at the silica/methanol interface. A strong peak at 2096 cm?1 assigned to the azides was observed for the first time by SFG. Using a cyano‐substituted alkyne, the decrease of the azide peak and the increase of the cyano peak (2234 cm?1) were probed simultaneously. From the kinetic analysis, the reaction order with respect to copper was determined to be 2.1, suggesting that CuAAC on the surface follows a similar mechanism as in solution. 相似文献
995.
Disappearance and global existence of interfaces for a doubly degenerate parabolic equation with variable coefficient 下载免费PDF全文
Nan Li Liangchen Wang Chunlai Mu Pan Zheng 《Mathematical Methods in the Applied Sciences》2015,38(8):1465-1471
This paper deals with the Cauchy problem for a doubly degenerate parabolic equation with variable coefficient For the case λ + 1 ≥ N, one proves that depending on the behavior of the variable coefficient at infinity, the Cauchy problem either possesses the property of finite speed of propagation of perturbation or the support blows up in finite time. This completes a result by Tedeev (A.F.Tedeev, The interface blow‐up phenomenon and local estimates for doubly degenerate parabolic equations, Appl. Anal. 86 (2007) 755–782.), which asserts the same result under the condition λ + 1 < N. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
996.
Using the effective-field theory based on the Glauber-type stochastic dynamics (DEFT), we investigate dynamic phase transitions and dynamic phase diagrams of the Blume–Emery–Griffiths model under an oscillating magnetic field. We presented the dynamic phase diagrams in (T/J, h0/J), (D/J, T/J) and (K/J, T/J) planes, where T, h0, D, K and z are the temperature, magnetic field amplitude, crystal–field interaction, biquadratic interaction and the coordination number. The dynamic phase diagrams exhibit several ordered phases, coexistence phase regions and special critical points, as well as re-entrant behavior depending on interaction parameters. We also compare and discuss the results with the results of the same system within the mean-field theory based on the Glauber-type stochastic dynamics and find that some of the dynamic first-order phase lines and special dynamic critical points disappeared in the DEFT calculation. 相似文献
997.
998.
Dominika Lesnicki Zhen Zhang Mischa Bonn Marialore Sulpizi Ellen H. G. Backus 《Angewandte Chemie (International ed. in English)》2020,59(31):13116-13121
We investigate the dynamics of water in contact with solid calcium fluoride, where at low pH, localized charges can develop upon fluorite dissolution. We use 2D surface‐specific vibrational spectroscopy to quantify the heterogeneity of the interfacial water (D2O) molecules and provide information about the sub‐picosecond vibrational‐energy‐relaxation dynamics at the buried solid/liquid interface. We find that strongly H‐bonded OD groups, with a vibrational frequency below 2500 cm?1, display very rapid spectral diffusion and vibrational relaxation; for weakly H‐bonded OD groups, above 2500 cm?1, the dynamics slows down substantially. Atomistic simulations based on electronic‐structure theory reveal the molecular origin of energy transport through the local H‐bond network. We conclude that strongly oriented H‐bonded water molecules in the adsorbed layer, whose orientation is pinned by the localized charge defects, can exchange vibrational energy very rapidly due to the strong collective dipole, compensating for a partially missing solvation shell. 相似文献
999.
Mohammed Ahmed Ken‐ichi Inoue Satoshi Nihonyanagi Tahei Tahara 《Angewandte Chemie (International ed. in English)》2020,59(24):9498-9505
Water around hydrophobic groups mediates hydrophobic interactions that play key roles in many chemical and biological processes. Thus, the molecular‐level elucidation of the properties of water in the vicinity of hydrophobic groups is important. We report on the structure and dynamics of water at two oppositely charged hydrophobic ion/water interfaces, that is, the tetraphenylborate‐ion (TPB?)/water and tetraphenylarsonium‐ion (TPA+)/water interfaces, which are clarified by two‐dimensional heterodyne‐detected vibrational sum‐frequency generation (2D HD‐VSFG) spectroscopy. The obtained 2D HD‐VSFG spectra of the anionic TPB? interface reveal the existence of distinct π‐hydrogen bonded OH groups in addition to the usual hydrogen‐bonded OH groups, which are hidden in the steady‐state spectrum. In contrast, 2D HD‐VSFG spectra of the cationic TPA+ interface only show the presence of usual hydrogen‐bonded OH groups. The present study demonstrates that the sign of the interfacial charge governs the structure and dynamics of water molecules that face the hydrophobic region. 相似文献
1000.
Guobin Wen Bohua Ren Moon G. Park Jie Yang Haozhen Dou Zhen Zhang Ya‐Ping Deng Zhengyu Bai Lin Yang Jeff Gostick Gianluigi A. Botton Yongfeng Hu Zhongwei Chen 《Angewandte Chemie (International ed. in English)》2020,59(31):12860-12867
Simultaneously improving energy efficiency (EE) and material stability in electrochemical CO2 conversion remains an unsolved challenge. Among a series of ternary Sn‐Ti‐O electrocatalysts, 3D ordered mesoporous (3DOM) Sn0.3Ti0.7O2 achieves a trade‐off between active‐site exposure and structural stability, demonstrating up to 71.5 % half‐cell EE over 200 hours, and a 94.5 % Faradaic efficiency for CO at an overpotential as low as 430 mV. DFT and X‐ray absorption fine structure analyses reveal an electron density reconfiguration in the Sn‐Ti‐O system. A downshift of the orbital band center of Sn and a charge depletion of Ti collectively facilitate the dissociative adsorption of the desired intermediate COOH* for CO formation. It is also beneficial in maintaining a local alkaline environment to suppress H2 and formate formation, and in stabilizing oxygen atoms to prolong durability. These findings provide a new strategy in materials design for efficient CO2 conversion and beyond. 相似文献