全文获取类型
收费全文 | 1131篇 |
免费 | 131篇 |
国内免费 | 105篇 |
专业分类
化学 | 758篇 |
晶体学 | 8篇 |
力学 | 63篇 |
综合类 | 7篇 |
数学 | 180篇 |
物理学 | 351篇 |
出版年
2024年 | 4篇 |
2023年 | 23篇 |
2022年 | 40篇 |
2021年 | 30篇 |
2020年 | 30篇 |
2019年 | 38篇 |
2018年 | 26篇 |
2017年 | 22篇 |
2016年 | 50篇 |
2015年 | 43篇 |
2014年 | 46篇 |
2013年 | 70篇 |
2012年 | 86篇 |
2011年 | 100篇 |
2010年 | 64篇 |
2009年 | 79篇 |
2008年 | 74篇 |
2007年 | 65篇 |
2006年 | 74篇 |
2005年 | 44篇 |
2004年 | 46篇 |
2003年 | 41篇 |
2002年 | 23篇 |
2001年 | 18篇 |
2000年 | 31篇 |
1999年 | 36篇 |
1998年 | 19篇 |
1997年 | 24篇 |
1996年 | 15篇 |
1995年 | 9篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有1367条查询结果,搜索用时 0 毫秒
991.
Jiaxiao Yuan Xiaomin Zhang Dawei Zhou Feixiang Ge Jingxian Zhong Sihan Zhao Zhenwei Ou Guixiang Zhan Xu Zhang Congzhou Li Jin Tang Qi Bai Junran Zhang Chao Zhu Ti Wang Longfei Ruan Chongqin Zhu Xuefen Song Wei Huang Lin Wang 《Angewandte Chemie (International ed. in English)》2023,62(19):e202218546
The liquid-air interface offers a platform for the in-plane growth of free-standing materials. However, it is rarely used for inorganic perovskites and ultrathin non-layered perovskites. Herein the liquid-air interfacial synthesis of inorganic perovskite nanosheets (Cs3Bi2I9, Cs3Sb2I9) is achieved simply by drop-casting the precursor solution with only the addition of iodine. The products are inaccessible without iodine addition. The thickness and lateral size of these nanosheets can be adjusted through the iodine concentration. The high volatility of the iodine spontaneously drives precursors that normally stay in the liquid to the liquid-air interface. The iodine also repairs in situ iodine vacancies during perovskite growth, giving enhanced optical and optoelectronic properties. The liquid-air interfacial growth of ultrathin perovskites provides multi-degree-of-freedom for constructing perovskite-based heterostructures and devices at atomic scale. 相似文献
992.
Dr. Shangbo Ning Dr. Honghui Ou Dr. Yaguang Li Dr. Cuncai Lv Prof. Shufang Wang Prof. Dingsheng Wang Prof. Jinhua Ye 《Angewandte Chemie (International ed. in English)》2023,62(23):e202302253
Solar-driven CO2 hydrogenation into multi-carbon products is a highly desirable, but challenging reaction. The bottleneck of this reaction lies in the C−C coupling of C1 intermediates. Herein, we construct the C−C coupling centre for C1 intermediates via the in situ formation of Co0−Coδ+ interface double sites on MgAl2O4 (Co−CoOx/MAO). Our experimental and theoretical prediction results confirmed the effective adsorption and activation of CO2 by the Co0 site to produce C1 intermediates, while the introduction of the electron-deficient state of Coδ+ can effectively reduce the energy barrier of the key CHCH* intermediates. Consequently, Co−CoOx/MAO exhibited a high C2–4 hydrocarbons production rate of 1303 μmol g−1 h−1; the total organic carbon selectivity of C2–4 hydrocarbons is 62.5 % under light irradiation with a high ratio (≈11) of olefin to paraffin. This study provides a new approach toward the design of photocatalysts used for CO2 conversion into C2+ products. 相似文献
993.
Dr. Yufei Zhao Ziyan Shen Dr. Juanjuan Huo Dr. Xianjun Cao Dr. Pengfei Ou Junpeng Qu Prof. Xinming Nie Dr. Jinqiang Zhang Prof. Minghong Wu Prof. Guoxiu Wang Prof. Hao Liu 《Angewandte Chemie (International ed. in English)》2023,62(36):e202308349
Electrocatalysts for highly efficient oxygen reduction reaction (ORR) are crucial for energy conversion and storage devices. Single-atom catalysts with maximized metal utilization and altered electronic structure are the most promising alternatives to replace current benchmark precious metals. However, the atomic level understanding of the functional role for each species at the anchoring sites is still unclear and poorly elucidated. Herein, we report Fe single atom catalysts with the sulfur and oxygen functional groups near the atomically dispersed metal centers (Fe1/NSOC) for highly efficient ORR. The Fe1/NSOC delivers a half-wave potential of 0.92 V vs. RHE, which is much better than those of commercial Pt/C (0.88 V), Fe single atoms on N-doped carbon (Fe1/NC, 0.89 V) and most reported nonprecious metal catalysts. The spectroscopic measurements reveal that the presence of sulfur group induces the formation of epoxy groups near the FeN4S2 centers, which not only modulate the electronic structure of Fe single atoms but also participate the catalytic process to improve the kinetics. The density functional theory calculations demonstrate the existence of sulfur and epoxy group engineer the charges of Fe reactive center and facilitate the reductive release of OH* (rate-limiting step), thus boosting the overall oxygen reduction efficiency. 相似文献
994.
Dr. Mingruo Ding Pengcheng Ou Xuening Li Yinghua Yu Mengmeng Niu Yongjian Yang Yewei Huang Prof. Dr. Zhi-Xiang Wang Prof. Dr. Xueliang Huang 《Angewandte Chemie (International ed. in English)》2023,62(18):e202300703
“Through space” palladium/hydrogen shift is an efficient strategy to achieve selective functionalization of a specific remote C−H bond. Compared with relatively extensive exploited 1,4-palladium migration process, the relevant 1,5-Pd/H shift was far less investigated. We herein report a novel 1,5-Pd/H shift pattern between a vinyl and an acyl group. Through the pattern, rapid access to 5-membered-dihydrobenzofuran and indoline derivatives has been achieved. Further studies have unveiled an unprecedented trifunctionalization (vinylation, alkynylation and amination) of a phenyl ring through 1,5-palladium migration relayed decarbonylative Catellani type reaction. A series of mechanistic investigations and DFT calculations have provided insights into the reaction pathway. Notably, it was unveiled that the 1,5-palladium migration in our case prefers a stepwise mechanism involving a PdIV intermediate. 相似文献
995.
Yu Luo Beiping Zhang Chenchen Liu Prof. Dehua Xia Dr. Xinwen Ou Yanpeng Cai Prof. Yang Zhou Prof. Jin Jiang Prof. Bin Han 《Angewandte Chemie (International ed. in English)》2023,62(26):e202305355
Photocatalytic oxygen reduction reaction (ORR) offers a promising hydrogen peroxide (H2O2) synthetic strategy, especially the one-step two-electron (2e−) ORR route holds great potential in achieving highly efficient and selectivity. However, efficient one-step 2e− ORR is rarely harvested and the underlying mechanism for regulating the ORR pathways remains greatly obscure. Here, by loading sulfone units into covalent organic frameworks (FS-COFs), we present an efficient photocatalyst for H2O2 generation via one-step 2e− ORR from pure water and air. Under visible light irradiation, FS-COFs exert a superb H2O2 yield of 3904.2 μmol h−1 g−1, outperforming most reported metal-free catalysts under similar conditions. Experimental and theoretical investigation reveals that the sulfone units accelerate the separation of photoinduced electron-hole (e−-h+) pairs, enhance the protonation of COFs, and promote O2 adsorption in the Yeager-type, which jointly alters the reaction process from two-step 2e− ORR to the one-step one, thereby achieving efficient H2O2 generation with high selectivity. 相似文献
996.
We proved the existence of convex solution to a class of fully nonlinear elliptic equations with second boundary condition on uniformly convex domains in \(\mathbb {R}^{n}\), and then applied it to solve a boundary value problem for minimal Lagrangian graphs in the pseudo-Euclidean space \(\mathbb {R}^{2n}_n\). 相似文献
997.
Functional nucleic acids (FNAs)-based biosensors have shown great potential in heavy metal ions detection due to their low-cost and easy to operate merits. However, in most FNAs based fluorescence probes, the ingenious designs of double-labeled (fluorophore and quencher group) DNA sequence, not only bring the annoyance of organic synthesis, but also restrict its use as a robust biosensor in practical duties. In this paper, we design a simple AIEgens functional nucleic acids (AFNAs) probe which consists of only fluorogen but no quencher group. With the help of duplex-specific nuclease (DSN) enzyme based target recycling, high fluorescence signal and superior sensitivity towards Hg2+ are achieved. This robust assay allows for sensitive and selective detection of Hg2+ in real water samples and mapping of intracellular Hg2+, without double-labeling of oligonucleotide with a dye-quencher pair, nor the multiple assay steps. 相似文献
998.
通过合理分子设计,合成了分别含有柱芳烃主体基元和氰基客体基元且具有不同尺寸的吡啶给体D1和D2,同时选择120?双铂金属盐A作为受体,从三组分出发,通过"一锅法"配位键导向自组装,自分类得到分别含有3个柱[5]芳烃单元的金属有机大环H和含有3个氰基中性客体的金属有机大环G.随着体系浓度增大,通过柱芳烃共价大环与中性氰基客体之间主客相互作用,逐级自组装形成以2种分立金属有机大环为交联点的新型超分子聚合物.所得到的超分子聚合物通过变浓度核磁氢谱(1H-NMR)、动态光散射(DLS)、二维核磁扩散序谱(DOSY)、扫描电镜(SEM)等进行了表征.有趣的是,进一步增加浓度(9.9 wt%),超分子聚合物转化成超分子聚合物凝胶,并且在温度、中性有机小分子及卤素离子等多重刺激下实现凝胶-溶液的可逆转化. 相似文献
999.
Haiyang Zhang Junjie Ou Yinmao Wei Hongwei Wang Zhongshan Liu Lianfang Chen Hanfa Zou 《Analytica chimica acta》2015
Low column efficiency for small molecules in reversed-phase chromatography is a major problem commonly encountered in polymer-based monoliths. Herein, a novel highly crosslinked porous polymeric monolith was in situ prepared by using a multi-acrylate monomer, dipentaerythritol penta-/hexa-acrylate (DPEPA), as crosslinker, which copolymerized with lauryl methacrylate (LMA) as functional monomer in a UV-transparent fused-silica capillary via photo-initiated free-radical polymerization within 5 min. The mechanical stability and permeability of the resulting poly(LMA-co-DPEPA) monolith were characterized in detail. One series of highly crosslinked poly(LMA-co-DPEPA) columns were prepared with relatively higher content of crosslinker (63.3%) in the precursor. Although they exhibited lower permeability, high column efficiency for alkylbenzenes was acquired in cLC, and the minimum plate height (column B) was in the range of 6.04–9.00 μm, corresponding to 111,000–165,000 N m−1. Meanwhile, another series of poly(LMA-co-DPEPA) columns prepared with relatively lower content of crosslinker (52.7%) in the precursor exhibited higher permeability, but the minimum plate height (column E) was relatively low in the range of 10.75–20.04 μm for alkylbenzenes, corresponding to 50,000–93,000 N m−1. Compared with common poly(LMA-co-EDMA) columns previously reported, the highly crosslinked poly(LMA-co-DPEPA) columns using a multi-acrylate monomer as crosslinker possessed remarkably high column efficiency for small molecules in cLC. By plotting of plate height (H) of alkylbenzenes versus the linear velocity (u) of mobile phase, the results revealed a retention-independent efficient performance of small molecules in the isocratic elution, indicating that the use of multi-functional crosslinker possibly prevents the generation of gel-like micropores in the poly(LMA-co-DPEPA) monolith, reducing the mass transfer resistance (C-term). 相似文献
1000.
Yan Shao Dan‐Wei Ou‐Yang Liang Cheng Wen Gao Xiao‐Xiang Weng De‐Yun Kong 《Helvetica chimica acta》2015,98(5):683-690
Three new pentacyclic triterpenoids, named centellasaponins G, H, and F ( 1 – 3 , resp.), together with four known compounds, 4 – 7 , were isolated from the whole plants of Centella asiatica. Their structures were elucidated on the basis of chemical and spectral analysis, including 1D‐ and 2D‐NMR and HR‐MS experiments, and by comparison with literature data. 相似文献