全文获取类型
收费全文 | 6827篇 |
免费 | 354篇 |
国内免费 | 360篇 |
专业分类
化学 | 5223篇 |
晶体学 | 5篇 |
力学 | 1289篇 |
综合类 | 5篇 |
数学 | 88篇 |
物理学 | 931篇 |
出版年
2023年 | 75篇 |
2022年 | 74篇 |
2021年 | 56篇 |
2020年 | 80篇 |
2019年 | 65篇 |
2018年 | 55篇 |
2017年 | 134篇 |
2016年 | 249篇 |
2015年 | 287篇 |
2014年 | 162篇 |
2013年 | 222篇 |
2012年 | 338篇 |
2011年 | 448篇 |
2010年 | 363篇 |
2009年 | 458篇 |
2008年 | 348篇 |
2007年 | 379篇 |
2006年 | 326篇 |
2005年 | 295篇 |
2004年 | 270篇 |
2003年 | 226篇 |
2002年 | 127篇 |
2001年 | 107篇 |
2000年 | 133篇 |
1999年 | 80篇 |
1998年 | 101篇 |
1997年 | 116篇 |
1996年 | 115篇 |
1995年 | 111篇 |
1994年 | 111篇 |
1993年 | 118篇 |
1992年 | 71篇 |
1991年 | 89篇 |
1990年 | 64篇 |
1989年 | 76篇 |
1988年 | 117篇 |
1987年 | 94篇 |
1986年 | 97篇 |
1985年 | 124篇 |
1984年 | 116篇 |
1983年 | 73篇 |
1982年 | 114篇 |
1981年 | 112篇 |
1980年 | 101篇 |
1979年 | 114篇 |
1978年 | 69篇 |
1977年 | 13篇 |
1976年 | 27篇 |
1973年 | 18篇 |
1972年 | 16篇 |
排序方式: 共有7541条查询结果,搜索用时 234 毫秒
21.
22.
Ivan Zuliani Andrea Fattori Rossella Svigelj Nicolò Dossi Cristian Grazioli Gino Bontempelli Rosanna Toniolo 《Electroanalysis》2023,35(2):e202200150
A convenient assembly recently proposed for screen printed gold electrodes (SPEs) suitable for measurements in gaseous samples is here tested for the analysis of the ethanol content in alcoholic drinks. This assembly involves the use of a circular crown of filter paper, soaked in the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hydrogen sulfate, which is simply placed upon a disposable screen printed cell, so as to contact the outer edge of the gold disc working electrode, as well as peripheral counter and reference electrodes. The electrical contact between the paper crown soaked in RTIL and the SPE electrode is assured by a gasket and all components are installed in a polylactic acid holder. This assembly provides a portable and disposable electrochemical platform, assembled by the easy immobilization onto a porous and inexpensive supporting material such as paper of a RTIL characterized by profitable electrical conductivity and negligible vapor pressure. The electroanalytical performance of this device was assayed for the flow injection analysis of the ethanol concentration in some real samples of wine and beer and the results obtained are compared with the alcoholic degree reported in the relevant bottle-labels, thus highlighting a substantially satisfactory agreement. Repeatable sharp peaks (RSD=6–8 %) were detected for ethanol over a wide linear range (1–20 % v/v in water) and a detection and quantitation limit of 0.55 % v/v and 1.60 % v/v were inferred for a signal-to-noise ratio of 3 and 10, respectively. 相似文献
23.
Di Liu Jiyan Pei Prof. Xu Zhang Xiao-Wen Gu Prof. Hui-Min Wen Prof. Banglin Chen Prof. Guodong Qian Prof. Bin Li 《Angewandte Chemie (International ed. in English)》2023,62(12):e202218590
Developing porous materials for C3H6/C3H8 separation faces the challenge of merging excellent separation performance with high stability and easy scalability of synthesis. Herein, we report a robust Hofmann clathrate material (ZJU-75a), featuring high-density strong binding sites to achieve all the above requirements. ZJU-75a adsorbs large amount of C3H6 with a record high storage density of 0.818 g mL−1, and concurrently shows high C3H6/C3H8 selectivity (54.2) at 296 K and 1 bar. Single-crystal structure analysis unveil that the high-density binding sites in ZJU-75a not only provide much stronger interactions with C3H6 but also enable the dense packing of C3H6. Breakthrough experiments on gas mixtures afford both high separation factor of 14.7 and large C3H6 uptake (2.79 mmol g−1). This material is highly stable and can be easily produced at kilogram-scale using a green synthesis method, making it as a benchmark material to address major challenges for industrial C3H6/C3H8 separation. 相似文献
24.
Lu Wang Wenjuan Xue Hejin Zhu Xiangyu Guo Hongliang Huang Prof. Chongli Zhong 《Angewandte Chemie (International ed. in English)》2023,62(11):e202218596
The separation of isomeric C4 paraffins is an important task in the petrochemical industry, while current adsorbents undergo a trade-off relationship between selectivity and adsorption capacity. In this work, the pore aperture of a cage-like Zn-bzc (bzc=pyrazole-4-carboxylic acid) is tuned by the stepwise installation methyl groups on its narrow aperture to achieve both molecular-sieving separation and high n-C4H10 uptake. Notably, the resulting Zn-bzc-2CH3 (bzc-2CH3=3,5-dimethylpyrazole-4-carboxylic acid) can sensitively capture n-C4H10 and exclude iso-C4H10, affording molecular-sieving for n-C4H10/iso-C4H10 separation and high n-C4H10 adsorption capacity (54.3 cm3 g−1). Breakthrough tests prove n-C4H10/iso-C4H10 can be efficiently separated and high-purity iso-C4H10 (99.99 %) can be collected. Importantly, the hydrophobic microenvironment created by the introduced methyl groups greatly improves the stability of Zn-bzc and significantly eliminates the negative effect of water vapor on gas separation under humid conditions, indicating Zn-bzc-2CH3 is a new benchmark adsorbent for n-C4H10/iso-C4H10 separation. 相似文献
25.
Cong Yu Zhengdong Guo Lifeng Yang Jiyu Cui Sen Chen Yawen Bo Xian Suo Qihan Gong Shang Zhang Prof. Xili Cui Shengbao He Prof. Huabin Xing 《Angewandte Chemie (International ed. in English)》2023,62(16):e202218027
Adsorptive separation is an energy-efficient alternative, but its advancement has been hindered by the challenge of industrially potential adsorbents development. Herein, a novel ultra-microporous metal-organic framework ZU-901 is designed that satisfies the basic criteria raised by ethylene/ethane (C2H4/C2H6) pressure swing adsorption (PSA). ZU-901 exhibits an “S” shaped C2H4 curve with high sorbent selection parameter (65) and could be mildly regenerated. Through green aqueous-phase synthesis, ZU-901 is easily scalable with 99 % yield, and it is stable in water, acid, basic solutions and cycling breakthrough experiments. Polymer-grade C2H4 (99.51 %) could be obtained via a simulating two-bed PSA process, and the corresponding energy consumption is only 1/10 of that of simulating cryogenic distillation. Our work has demonstrated the great potential of pore engineering in designing porous materials with desired adsorption and desorption behavior to implement an efficient PSA process. 相似文献
26.
Ali Azmy Shunran Li Giasemi K. Angeli Claire Welton Parth Raval Min Li Nourdine Zibouche Lukasz Wojtas G. N. Manjunatha Reddy Peijun Guo Pantelis N. Trikalitis Ioannis Spanopoulos 《Angewandte Chemie (International ed. in English)》2023,62(12):e202218429
In this work we report a strategy for generating porosity in hybrid metal halide materials using molecular cages that serve as both structure-directing agents and counter-cations. Reaction of the [2.2.2] cryptand (DHS) linker with PbII in acidic media gave rise to the first porous and water-stable 2D metal halide semiconductor (DHS)2Pb5Br14. The corresponding material is stable in water for a year, while gas and vapor-sorption studies revealed that it can selectively and reversibly adsorb H2O and D2O at room temperature (RT). Solid-state NMR measurements and DFT calculations verified the incorporation of H2O and D2O in the organic linker cavities and shed light on their molecular configuration. In addition to porosity, the material exhibits broad light emission centered at 617 nm with a full width at half-maximum (FWHM) of 284 nm (0.96 eV). The recorded water stability is unparalleled for hybrid metal halide and perovskite materials, while the generation of porosity opens new pathways towards unexplored applications (e.g. solid-state batteries) for this class of hybrid semiconductors. 相似文献
27.
Jianbo Yu Aidaer Muhetaer Xiaowen Gao Zhenzhen Zhang Yuying Yang Prof. Qi Li Prof. Langxing Chen Prof. Haichao Liu Prof. Dongsheng Xu 《Angewandte Chemie (International ed. in English)》2023,62(28):e202303135
Photo-assisted reverse water gas shift (RWGS) reaction is regarded green and promising in controlling the reaction gas ratio in Fischer Tropsch synthesis. But it is inclined to produce more byproducts in high H2 concentration condition. Herein, LaInO3 loaded with Ni-nanoparticles (Ni NPs) was designed to obtain an efficient photothermal RWGS reaction rate, where LaInO3 was enriched with oxygen vacancies to roundly adsorbing CO2 and the strong interaction with Ni NPs endowed the catalysts with powerful H2 activity. The optimized catalyst performed a large CO yield rate (1314 mmol gNi−1 h−1) and ≈100 % selectivity. In situ characterizations demonstrated a COOH* pathway of the reaction and photoinduced charge transfer process for reducing the RWGS reaction active energy. Our work provides valuable insights on the construction of catalysts concerning products selectivity and photoelectronic activating mechanism on CO2 hydrogenation. 相似文献
28.
Dr. Yuanxing Zhang Prof. Qingquan Tang Dr. Zi Li Prof. Ke Zhang 《Angewandte Chemie (International ed. in English)》2023,62(24):e202302527
It is a formidable challenge in polycondensation to simultaneously construct multiple covalent bonds to prepare double-stranded polymers of intrinsic microporosity (PIMs) with fused multicyclic linkages. To the best of our knowledge, this is the first study to develop a self-accelerating Diels–Alder reaction for successfully preparing double-stranded PIMs with fused multicyclic backbone structures. A self-accelerating Diels–Alder reaction was developed based on the [4+2] cycloaddition of sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DIBOD) and ortho-quinone compounds. In this reaction, the cycloaddition of ortho-quinone with the first alkyne of DIBOD activates the second alkyne, which reacts with ortho-quinone at a rate constant 192 times larger than that of the original alkyne. Using this self-accelerating reaction to polymerize DIBOD and spirocyclic/cyclic difunctional ortho-quinone monomers, a novel stoichiometric imbalance-promoted step-growth polymerization method was developed to prepare PIMs. The resultant PIMs possess intrinsic ultramicropores with pore sizes between 0.45 to 0.7 nm, high specific surface areas above 646 m2 g−1, and good H2 separation performance. 相似文献
29.
Shubo Geng Hang Xu Chun-Shuai Cao Prof. Tony Pham Prof. Bin Zhao Prof. Zhenjie Zhang 《Angewandte Chemie (International ed. in English)》2023,62(32):e202305390
Adsorption-based removal of carbon dioxide (CO2) from gas mixtures has demonstrated great potential for solving energy security and environmental sustainability challenges. However, due to similar physicochemical properties between CO2 and other gases as well as the co-adsorption behavior, the selectivity of CO2 is severely limited in currently reported CO2-selective sorbents. To address the challenge, we create a bioinspired design strategy and report a robust, microporous metal–organic framework (MOF) with unprecedented [Mn86] nanocages. Attributed to the existence of unique enzyme-like confined pockets, strong coordination interactions and dipole-dipole interactions are generated for CO2 molecules, resulting in only CO2 molecules fitting in the pocket while other gas molecules are prohibited. Thus, this MOF can selectively remove CO2 from various gas mixtures and show record-high selectivities of CO2/CH4 and CO2/N2 mixtures. Highly efficient CO2/C2H2, CO2/CH4, and CO2/N2 separations are achieved, as verified by experimental breakthrough tests. This work paves a new avenue for the fabrication of adsorbents with high CO2 selectivity and provides important guidance for designing highly effective adsorbents for gas separation. 相似文献
30.
Dr. Wei-Hua Deng Prof. Qiao-Hong Li Jie Chen Chuan-Zhe Wang Dr. Zhi-Hua Fu Dr. Xiao-Liang Ye Prof. Guan-E Wang Prof. Gang Xu 《Angewandte Chemie (International ed. in English)》2023,62(31):e202305977
The electronic conductivity (EC) of metal–organic frameworks (MOFs) is sensitive to strongly oxidizing guest molecules. Water is a relatively mild species, however, the effect of H2O on the EC of MOFs is rarely reported. We explored the effect of H2O on the EC in the MOFs (NH2)2-MIL-125 and its derivatives with experimental and theoretical investigations. Unexpectedly, a large EC increase of 107 on H2SO4@(NH2)2-MIL-125 by H2O was observed. Brønsted acid–base pairs formed with the −NH2 groups, and H2SO4 played an important role in promoting the charge transfer from H2O to the MOF. Based on H2SO4@(NH2)2-MIL-125, a high-performance chemiresistive humidity sensor was developed with the highest sensitivity, broadest detection range, and lowest limit of detection amongst all reported sensing materials to date. This work not only demonstrated that H2O can remarkably influence the EC of MOFs, but it also revealed that post-modification of the structure of MOFs could enhance the influence of the guest molecule on their EC to design high-performance sensing materials. 相似文献