全文获取类型
收费全文 | 1620篇 |
免费 | 399篇 |
国内免费 | 317篇 |
专业分类
化学 | 1962篇 |
晶体学 | 9篇 |
力学 | 22篇 |
综合类 | 4篇 |
数学 | 27篇 |
物理学 | 312篇 |
出版年
2024年 | 27篇 |
2023年 | 38篇 |
2022年 | 105篇 |
2021年 | 171篇 |
2020年 | 338篇 |
2019年 | 140篇 |
2018年 | 121篇 |
2017年 | 77篇 |
2016年 | 174篇 |
2015年 | 134篇 |
2014年 | 132篇 |
2013年 | 112篇 |
2012年 | 71篇 |
2011年 | 60篇 |
2010年 | 33篇 |
2009年 | 60篇 |
2008年 | 115篇 |
2007年 | 73篇 |
2006年 | 85篇 |
2005年 | 62篇 |
2004年 | 49篇 |
2003年 | 46篇 |
2002年 | 21篇 |
2001年 | 16篇 |
2000年 | 16篇 |
1999年 | 7篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1994年 | 6篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有2336条查询结果,搜索用时 78 毫秒
141.
Yuanjuan Bai Dr. Huijuan Zhang Li Liu Haitao Xu Prof. Dr. Yu Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):1021-1029
The superior properties of nanomaterials with a special structure can provide prospects for highly efficient water splitting and lithium storage. Herein, we fabricated a series of peapodlike C@Ni2?xCoxP (x≤1) nanocomposites by an anion‐exchange pathway. The experimental results indicated that the HER activity of C@Ni2?xCoxP catalyst is strongly related to the Co/Ni ratio, and the C@NiCoP got the highest HER activity with low onset potential of ~45 mV, small Tafel slope of ~43 mV dec?1, large exchange current density of 0.21 mA cm?2, and high long‐term durability (60 h) in 0.5 m H2SO4 solutions. Equally importantly, as an anode electrode for lithium batteries, this peapodlike C@NiCoP nanocomposite gives excellent charge–discharge properties (e.g., specific capacity of 670 mAh g?1 at 0.2 A g?1 after 350 cycles, and a reversible capacity of 405 mAh g?1 at a high current rate of 10 A g?1). The outstanding performance of C@NiCoP in HER and LIBs could be attributed to the synergistic effect of the rational design of peapodlike nanostructures and the introduction of Co element. 相似文献
142.
Hairong Xue Dr. Jianqing Zhao Jing Tang Hao Gong Prof. Ping He Prof. Haoshen Zhou Prof. Yusuke Yamauchi Prof. Jianping He 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4915-4923
Tin oxide nanoparticles (SnO2 NPs) have been encapsulated in situ in a three‐dimensional ordered space structure. Within this composite, ordered mesoporous carbon (OMC) acts as a carbon framework showing a desirable ordered mesoporous structure with an average pore size (≈6 nm) and a high surface area (470.3 m2 g?1), and the SnO2 NPs (≈10 nm) are highly loaded (up to 80 wt %) and homogeneously distributed within the OMC matrix. As an anode material for lithium‐ion batteries, a SnO2@OMC composite material can deliver an initial charge capacity of 943 mAh g?1 and retain 68.9 % of the initial capacity after 50 cycles at a current density of 50 mA g?1, even exhibit a capacity of 503 mA h g?1 after 100 cycles at 160 mA g?1. In situ encapsulation of the SnO2 NPs within an OMC framework contributes to a higher capacity and a better cycling stability and rate capability in comparison with bare OMC and OMC ex situ loaded with SnO2 particles (SnO2/OMC). The significantly improved electrochemical performance of the SnO2@OMC composite can be attributed to the multifunctional OMC matrix, which can facilitate electrolyte infiltration, accelerate charge transfer, and lithium‐ion diffusion, and act as a favorable buffer to release reaction strains for lithiation/delithiation of the SnO2 NPs. 相似文献
143.
Dr. Dafang He Lixian Li Fengjuan Bai Chenyang Zha Prof. Liming Shen Prof. Harold H. Kung Prof. Ningzhong Bao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(13):4454-4459
A unique hierarchically nanostructured composite of iron oxide/carbon (Fe3O4/C) nanospheres‐doped three‐dimensional (3D) graphene aerogel has been fabricated by a one‐pot hydrothermal strategy. In this novel nanostructured composite aerogel, uniform Fe3O4 nanocrystals (5–10 nm) are individually embedded in carbon nanospheres (ca. 50 nm) forming a pomegranate‐like structure. The carbon matrix suppresses the aggregation of Fe3O4 nanocrystals, avoids direct exposure of the encapsulated Fe3O4 to the electrolyte, and buffers the volume expansion. Meanwhile, the interconnected 3D graphene aerogel further serves to reinforce the structure of the Fe3O4/C nanospheres and enhances the electrical conductivity of the overall electrode. Therefore, the carbon matrix and the interconnected graphene network entrap the Fe3O4 nanocrystals such that their electrochemical function is retained even after fracture. This novel hierarchical aerogel structure delivers a long‐term stability of 634 mA h g?1 over 1000 cycles at a high current density of 6 A g?1 (7 C), and an excellent rate capability of 413 mA h g?1 at 10 A g?1 (11 C), thus exhibiting great potential as an anode composite structure for durable high‐rate lithium‐ion batteries. 相似文献
144.
Muhammad Hilmy Alfaruqi Dr. Jihyeon Gim Sungjin Kim Jinju Song Pham Tung Duong Jeonggeun Jo Dr. Joseph Paul Baboo Dr. Zhiliang Xiu Dr. Vinod Mathew Prof. Jaekook Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):2039-2045
A nanostructured Mn3O4/C electrode was prepared by a one‐step polyol‐assisted pyro‐synthesis without any post‐heat treatments. The as‐prepared Mn3O4/C revealed nanostructured morphology comprised of secondary aggregates formed from carbon‐coated primary particles of average diameters ranging between 20 and 40 nm, as evidenced from the electron microscopy studies. The N2 adsorption studies reveal a hierarchical porous feature in the nanostructured electrode. The nanostructured morphology appears to be related to the present rapid combustion strategy. The nanostructured porous Mn3O4/C electrode demonstrated impressive electrode properties with reversible capacities of 666 mAh g?1 at a current density of 33 mA g?1, good capacity retentions (1141 mAh g?1 with 100 % Coulombic efficiencies at the 100th cycle), and rate capabilities (307 and 202 mAh g?1 at 528 and 1056 mA g?1, respectively) when tested as an anode for lithium‐ion battery applications. 相似文献
145.
Dr. Lars Borchardt Dr. Martin Oschatz Prof. Dr. Stefan Kaskel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(22):7324-7351
Lithium–sulfur batteries are among the most promising electrochemical energy storage devices of the near future. Especially the low price and abundant availability of sulfur as the cathode material and the high theoretical capacity in comparison to state‐of‐the art lithium‐ion technologies are attractive features. Despite significant research achievements that have been made over the last years, fundamental (electro‐) chemical questions still remain unanswered. This review addresses ten crucial questions associated with lithium–sulfur batteries and critically evaluates current research with respect to them. The sulfur–carbon composite cathode is a particular focus, but its complex interplay with other hardware components in the cell, such as the electrolyte and the anode, necessitates a critical discussion of other cell components. Modern in situ characterisation methods are ideally suited to illuminate the role of each component. This article does not pretend to summarise all recently published data, but instead is a critical overview over lithium–sulfur batteries based on recent research findings. 相似文献
146.
Marco Carboni Dr. Andrea Giacomo Marrani Dr. Riccardo Spezia Dr. Sergio Brutti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17188-17203
The reaction thermodynamics of the 1,2‐dimethoxyethane (DME), a model solvent molecule commonly used in electrolytes for Li?O2 rechargeable batteries, has been studied by first‐principles methods to predict its degradation processes in highly oxidizing environments. In particular, the reactivity of DME towards the superoxide anion O2? in oxygen‐poor or oxygen‐rich environments is studied by density functional calculations. Solvation effects are considered by employing a self‐consistent reaction field in a continuum solvation model. The degradation of DME occurs through competitive thermodynamically driven reaction paths that end with the formation of partially oxidized final products such as formaldehyde and methoxyethene in oxygen‐poor environments and methyl oxalate, methyl formate, 1‐formate methyl acetate, methoxy ethanoic methanoic anhydride, and ethylene glycol diformate in oxygen‐rich environments. This chemical reactivity indirectly behaves as an electroactive parasitic process and therefore wastes part of the charge exchanged in Li?O2 cells upon discharge. This study is the first complete rationale to be reported about the degradation chemistry of DME due to direct interaction with O2?/O2 molecules. These findings pave the way for a rational development of new solvent molecules for Li?O2 electrolytes. 相似文献
147.
Enhanced Electrochemical Kinetics on Conductive Polar Mediators for Lithium–Sulfur Batteries 下载免费PDF全文
Hong‐Jie Peng Ge Zhang Xiang Chen Ze‐Wen Zhang Wen‐Tao Xu Prof. Jia‐Qi Huang Prof. Qiang Zhang 《Angewandte Chemie (International ed. in English)》2016,55(42):12990-12995
Lithium–sulfur (Li–S) batteries have been recognized as promising substitutes for current energy‐storage technologies owing to their exceptional advantage in energy density. The main challenge in developing highly efficient and long‐life Li–S batteries is simultaneously suppressing the shuttle effect and improving the redox kinetics. Polar host materials have desirable chemisorptive properties to localize the mobile polysulfide intermediates; however, the role of their electrical conductivity in the redox kinetics of subsequent electrochemical reactions is not fully understood. Conductive polar titanium carbides (TiC) are shown to increase the intrinsic activity towards liquid–liquid polysulfide interconversion and liquid–solid precipitation of lithium sulfides more than non‐polar carbon and semiconducting titanium dioxides. The enhanced electrochemical kinetics on a polar conductor guided the design of novel hybrid host materials of TiC nanoparticles grown within a porous graphene framework (TiC@G). With a high sulfur loading of 3.5 mg cm?2, the TiC@G/sulfur composite cathode exhibited a substantially enhanced electrochemical performance. 相似文献
148.
Zhixin Xu Prof. Jiulin Wang Prof. Jun Yang Xiaowei Miao Prof. Renjie Chen Ji Qian Rongrong Miao 《Angewandte Chemie (International ed. in English)》2016,55(35):10372-10375
The lithium–sulfur battery is regarded as one of the most promising candidates for lithium–metal batteries with high energy density. However, dendrite Li formation and low cycle efficiency of the Li anode as well as unstable sulfur based cathode still hinder its practical application. Herein a novel electrolyte (1 m LiODFB/EC‐DMC‐FEC) is designed not only to address the above problems of Li anode but also to match sulfur cathode perfectly, leading to extraordinary electrochemical performances. Using this electrolyte, lithium|lithium cells can cycle stably for above 2000 hours and the average Coulumbic efficiency reaches 98.8 %. Moreover, the Li–S battery delivers a reversible capacity of about 1400 mAh g?1sulfur with retention of 89 % for 1100 cycles at 1 C, and a capacity above 1100 mAh g?1sulfur at 10 C. The more advantages of this cell system are its outstanding cycle stability at 60 °C and no self‐discharge phenomena. 相似文献
149.
Integrated Photoelectrochemical Solar Energy Conversion and Organic Redox Flow Battery Devices 下载免费PDF全文
Wenjie Li Hui‐Chun Fu Dr. Linsen Li Dr. Miguel Cabán‐Acevedo Prof. Jr‐Hau He Prof. Song Jin 《Angewandte Chemie (International ed. in English)》2016,55(42):13104-13108
Building on regenerative photoelectrochemical solar cells and emerging electrochemical redox flow batteries (RFBs), more efficient, scalable, compact, and cost‐effective hybrid energy conversion and storage devices could be realized. An integrated photoelectrochemical solar energy conversion and electrochemical storage device is developed by integrating regenerative silicon solar cells and 9,10‐anthraquinone‐2,7‐disulfonic acid (AQDS)/1,2‐benzoquinone‐3,5‐disulfonic acid (BQDS) RFBs. The device can be directly charged by solar light without external bias, and discharged like normal RFBs with an energy storage density of 1.15 Wh L?1 and a solar‐to‐output electricity efficiency (SOEE) of 1.7 % over many cycles. The concept exploits a previously undeveloped design connecting two major energy technologies and promises a general approach for storing solar energy electrochemically with high theoretical storage capacity and efficiency. 相似文献
150.
Insight into the Interfacial Process and Mechanism in Lithium–Sulfur Batteries: An In Situ AFM Study 下载免费PDF全文
Shuang‐Yan Lang Yang Shi Prof. Dr. Yu‐Guo Guo Prof. Dr. Dong Wang Prof. Dr. Rui Wen Prof. Dr. Li‐Jun Wan 《Angewandte Chemie (International ed. in English)》2016,55(51):15835-15839
Lithium–sulfur (Li–S) batteries are highly appealing for large‐scale energy storage. However, performance deterioration issues remain, which are highly related to interfacial properties. Herein, we present a direct visualization of the interfacial structure and dynamics of the Li–S discharge/charge processes at the nanoscale. In situ atomic force microscopy and ex situ spectroscopic methods directly distinguish the morphology and growth processes of insoluble products Li2S2 and Li2S. The monitored interfacial dynamics show that Li2S2 nanoparticle nuclei begin to grow at 2 V followed by a fast deposition of lamellar Li2S at 1.83 V on discharge. Upon charging, only Li2S depletes from the interface, leaving some Li2S2 undissolved, which accumulates during cycling. The galvanostatic precipitation of Li2S2 and/or Li2S is correlated to current rates and affects the specific capacity. These findings reveal a straightforward structure–reactivity correlation and performance fading mechanism in Li–S batteries. 相似文献