全文获取类型
收费全文 | 3367篇 |
免费 | 235篇 |
国内免费 | 418篇 |
专业分类
化学 | 3166篇 |
晶体学 | 27篇 |
力学 | 111篇 |
综合类 | 3篇 |
数学 | 29篇 |
物理学 | 684篇 |
出版年
2023年 | 90篇 |
2022年 | 38篇 |
2021年 | 41篇 |
2020年 | 54篇 |
2019年 | 43篇 |
2018年 | 41篇 |
2017年 | 67篇 |
2016年 | 151篇 |
2015年 | 152篇 |
2014年 | 157篇 |
2013年 | 206篇 |
2012年 | 239篇 |
2011年 | 297篇 |
2010年 | 219篇 |
2009年 | 240篇 |
2008年 | 189篇 |
2007年 | 229篇 |
2006年 | 191篇 |
2005年 | 194篇 |
2004年 | 201篇 |
2003年 | 142篇 |
2002年 | 121篇 |
2001年 | 84篇 |
2000年 | 82篇 |
1999年 | 78篇 |
1998年 | 60篇 |
1997年 | 79篇 |
1996年 | 61篇 |
1995年 | 65篇 |
1994年 | 34篇 |
1993年 | 30篇 |
1992年 | 26篇 |
1991年 | 25篇 |
1990年 | 23篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有4020条查询结果,搜索用时 15 毫秒
1.
This work presents a scalable approach for preparing spherical hollow mesoporous silica with high surface area/pore volume, serving as outstanding support for supported phosphotungstic acid catalyst with much superior catalytic performance to the one on previously reported spherical mesoporous silica toward diverse transformations, ascribed to the strengthened mass transfer and the enlarged exposure degree of acidic sites to reactants those resulting from unique hollow and mesoporous morphology. 相似文献
2.
《Journal of Saudi Chemical Society》2020,24(9):663-672
Nanoscaled palladium particles supported on graphitic carbon nitride (Pd0/g-C3N4) is prepared to improve the oxygen transfer in Wacker oxidation via chemical reduction method. From the analysis of FT-IR, XRD, SEM, TEM, XPS and ICP, Pd0 particles are firmly combined with g-C3N4 layers, and sub-surface ones occupy most of the components. It is worth mentioning that graphene oxide (GO), which is completely recyclable without further pollution, can be used as a ‘solid weak acid’ taking the place of H2SO4 and CF3COOH. Under the optimization conditions, as many as 46 kinds of olefins are transferred into corresponding products with satisfactory yields, and o-methyl styrene gets the highest yield of 94%. After five times of recycling experiment, the yield of acetophenone only decreases by about 7.0% in the uniform reaction process. In virtue of former research results and molecular electrostatic potential, a possible mechanism is put forward to explain the catalytic process. 相似文献
3.
设计开发了一种无需溶剂,通过热处理固相转化制备沸石咪唑酯骨架材料(ZIFs)的简易方法.该方法无需溶剂及其它预处理,只需将金属源与有机配体固相混合后于低温(200℃)热处理即可实现多孔晶体材料的制备.所合成材料H-ZIF-67为具有方纳石拓扑结构的纳米晶体,与传统方式合成的ZIFs材料一致.粉末X射线衍射(PXRD)分析结果表明产物的晶体结构与标准ZIFs谱图一致.通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、N2吸附-脱附分析、热重分析(TGA)和傅里叶变换红外光谱(FTIR)等手段对合成的材料进行了表征,发现H-ZIF-67材料具有与ZIFs材料类似的特性.该方法经济、高效,摒弃了传统方法合成ZIFs材料周期长、处理过程复杂的弊端,为ZIFs材料的量产提供了新思路. 相似文献
4.
Dr. Clémence Sicard 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202213405
Enzyme immobilization is a widely reported method to favor the applicability of enzymes by enhancing their stability and re-usability. Among the various existing solid supports and immobilization strategies, the in situ encapsulation of enzymes within crystalline porous matrices is a powerful tool to design biohybrids with a stable and protected catalytic activity. However, to date, only a few metal–organic frameworks (MOFs) and hydrogen-bonded organic frameworks (HOFs) have been reported. Excitingly, for the first time, Y. Chen and co-workers expanded the in situ bio-encapsulation to a new class of crystalline porous materials, namely covalent organic frameworks (COFs). The enzyme@COF materials not only exhibited high enzyme loading with minimal leaching, high catalytic activity and selectivity, chemical and long-term stability and recyclability but could also be scaled up to a few grams. Undoubtedly, this work opens new striking opportunities for enzymatic immobilization and will stimulate new research on COF-based matrices. 相似文献
5.
Taito Hashimoto Dr. Ryusei Oketani Masaki Nobuoka Prof. Dr. Shu Seki Prof. Dr. Ichiro Hisaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202215836
Porous frameworks composed of non-stoichiometrically mixed multicomponent molecules attract much attention from a functional viewpoint. However, their designed preparation and precise structural characterization remain challenging. Herein, we demonstrate that cocrystallization of tetrakis(4-carboxyphenyl)hexahydropyrene and pyrene derivatives ( CP-Hp and CP-Py , respectively) yields non-stoichiometric mixed frameworks through networking via hydrogen bonding. The composition ratio of CP-Hp and CP-Py in the framework was determined by single crystalline X-ray crystallographic analysis, indicating that the mixed frameworks were formed over a wide range of composition ratios. Furthermore, microscopic Raman spectroscopy on the single crystal indicates that the components are not uniformly distributed such as ideal solid solution, but are done gradationally or inhomogeneously. 相似文献
6.
Reversible Li Plating on Graphite Anodes through Electrolyte Engineering for Fast-Charging Batteries
Xinyang Yue Jing Zhang Yongteng Dong Yuanmao Chen Zhangqin Shi Xuejiao Xu Xunlu Li Prof. Zheng Liang 《Angewandte Chemie (International ed. in English)》2023,62(19):e202302285
The difficulties to identify the rate-limiting step cause the lithium (Li) plating hard to be completely avoided on graphite anodes during fast charging. Therefore, Li plating regulation and morphology control are proposed to address this issue. Specifically, a Li plating-reversible graphite anode is achieved via a localized high-concentration electrolyte (LHCE) to successfully regulate the Li plating with high reversibility over high-rate cycling. The evolution of solid electrolyte interphase (SEI) before and after Li plating is deeply investigated to explore the interaction between the lithiation behavior and electrochemical interface polarization. Under the fact that Li plating contributes 40 % of total lithiation capacity, the stable LiF-rich SEI renders the anode a higher average Coulombic efficiency (99.9 %) throughout 240 cycles and a 99.95 % reversibility of Li plating. Consequently, a self-made 1.2-Ah LiNi0.5Mn0.3Co0.2O2 | graphite pouch cell delivers a competitive retention of 84.4 % even at 7.2 A (6 C) after 150 cycles. This work creates an ingenious bridge between the graphite anode and Li plating, for realizing the high-performance fast-charging batteries. 相似文献
7.
Shengmei Chen Yiran Ying Shengnan Wang Longtao Ma Haitao Huang Xiaoqi Wang Xu Jin Shengchi Bai Prof. Chunyi Zhi 《Angewandte Chemie (International ed. in English)》2023,62(19):e202301467
Though massive efforts have been devoted to exploring Br-based batteries, the highly soluble Br2/Br3− species causing rigorous “shuttle effect”, leads to severe self-discharge and low Coulombic efficiency. Conventionally, quaternary ammonium salts such as methyl ethyl morpholinium bromide (MEMBr) and tetrapropylammonium bromide (TPABr) are used to fix Br2 and Br3−, but they occupy the mass and volume of battery without capacity contribution. Here, we report an all-active solid interhalogen compound, IBr, as a cathode to address the above challenges, in which the oxidized Br0 is fixed by iodine (I), thoroughly eliminating cross-diffusing Br2/Br3− species during the whole charging and discharging process. The Zn||IBr battery delivers remarkably high energy density of 385.8 Wh kg−1, which is higher than those of I2, MEMBr3, and TPABr3 cathodes. Our work provides new approaches to achieve active solid interhalogen chemistry for high-energy electrochemical energy storage devices. 相似文献
8.
Gunjoo Kim Seung-Hee Ryu Hojin Jeong Yunji Choi Seungwoo Lee Joon-Hwan Choi Hyunjoo Lee 《Angewandte Chemie (International ed. in English)》2023,62(30):e202306017
Inducing strong metal-support interaction (SMSI) has been a useful way to control the structure of surface active sites. The SMSI often causes the encapsulation of metal particles with an oxide layer. Herein, an amorphous ceria shell was formed on Cu nanoparticles under a mild gas condition with high activity and durability for surface reaction. Cu−Ce solid solution promoted the transfer of surface oxygen species, which induced the ceria shell formation on Cu nanoparticles. This catalyst was used for CO2 hydrogenation, selectively producing CO with high low-temperature activity and good durability for operation at high temperature. CO2 activation and H2 spillover could occur at low temperatures, enhancing the activity. The shell prevented the sintering, assuring durability. This catalyst was applied to a bench-scale reactor without loss in performance, resulting in high CO productivity in all temperature ranges. 相似文献
9.
Dr. Zachary T. Gossage Nanako Ito Prof. Tomooki Hosaka Prof. Ryoichi Tatara Prof. Shinichi Komaba 《Angewandte Chemie (International ed. in English)》2023,62(43):e202307446
The solid-electrolyte interphase (SEI) is key to stable, high voltage lithium-ion batteries (LIBs) as a protective barrier that prevents electrolyte decomposition. The SEI is thought to play a similar role in highly concentrated water-in-salt electrolytes (WISEs) for emerging aqueous batteries, but its properties remain unknown. In this work, we utilized advanced scanning electrochemical microscopy (SECM) and operando electrochemical mass spectrometry (OEMS) techniques to gain deeper insight into the SEI that occurs within highly concentrated WISEs. As a model, we focus on a 55 mol/kg K(FSA)0.6(OTf)0.4 electrolyte and a 3,4,9,10-perylenetetracarboxylic diimide negative electrode. For the first time, our work showed distinctly passivating structures with slow apparent electron transfer rates alike to the SEI found in LIBs. In situ analyses indicated stable passivating structures when PTCDI was stepped to low potentials (≈−1.3 V vs. Ag/AgCl). However, the observed SEI was discontinuous at the surface and H2 evolution occurred as the electrode reached more extreme potentials. OEMS measurements further confirmed a shift in the evolution of detectable H2 from −0.9 V to <−1.4 V vs. Ag/AgCl when changing from dilute to concentrated electrolytes. In all, our work shows a combined approach of traditional battery measurements with in situ analyses for improving characterization of other unknown SEI structures. 相似文献
10.
Dr. Jin Su Dr. Tohru Tsuruoka Dr. Takuji Tsujita Dr. Yuu Inatomi Dr. Kazuya Terabe 《Angewandte Chemie (International ed. in English)》2023,62(9):e202217203
Solid-state batteries (SSBs) that use solid electrolytes instead of flammable liquid electrolytes have the potential to generate higher specific capacity and offer better safety. Magnesium (Mg) based SSBs with Mg metal anodes are considered to be one of the most promising energy storage candidates, because it gives high theoretical volumetric capacities of 3830 mAh cm−3. Here, we demonstrate an atomic layer deposition (ALD) process with a double nitrogen plasma process that successfully produces nitrogen-incorporated magnesium phosphorus oxynitride (MgPON) solid-state electrolyte (SSE) thin films at a low deposition temperature of 125 °C. The ALD MgPON SSEs exhibit an ionic conductivity of 0.36 and 1.2 μS cm−1 at 450 and 500 °C, respectively. The proposed ALD strategy shows the ability of conformal deposition nitrogen-doped SSEs on pattered substrates and is attractive for using nitride ion-conducing films as protective or wetting interlayers in solid-state Mg and Li batteries. 相似文献