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101.
Facile Synthesis of Dibenzopentalene Dianions and Their Application as New π‐Extended Ligands 下载免费PDF全文
Takuya Kuwabara Dr. Kazuya Ishimura Prof. Dr. Takahiro Sasamori Prof. Dr. Norihiro Tokitoh Prof. Dr. Masaichi Saito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7571-7575
Reduction of phenyl(silyl)ethynes with potassium followed by quenching with iodine gave dibenzopentalenes in moderate yields. The intermediates of the reactions, dipotassium dibenzopentalenides, were isolated. The first dibenzopentalene–transition‐metal complex was successfully synthesized. The ruthenium atoms are located above the six‐membered rings. However, X‐ray diffraction analysis and theoretical calculations revealed that the aromatic nature of the five‐membered rings was retained. The cyclic voltammetry of the Ru complex revealed two oxidation waves with relatively large separation. 相似文献
102.
Isothermal Titration Calorimetry Study of a Bistable Supramolecular System: Reversible Complexation of Cryptand[2.2.2] with Potassium Ions 下载免费PDF全文
Maria G. del Rosso Dr. Artur Ciesielski Dr. Silvia Colella Prof. Jack M. Harrowfield Prof. Paolo Samorì 《Chemphyschem》2014,15(13):2743-2748
Isothermal titration calorimetry (ITC) is used to investigate the thermodynamics of the complexation of potassium ions by 1,10‐diaza‐4,7,13,16,21,24‐hexaoxabicyclo[8.8.8]hexacosane (cryptand[2.2.2]) in aqueous solution. By changing the pH of the solution it was possible to trigger the reversible complexation/decomplexation of the cryptand in consecutive in situ experiments and to assess for the first time the use of ITC to monitor the thermodynamics of a bistable system. 相似文献
103.
Dr. Fei Xu Yixuan Zhai En Zhang Qianhui Liu Guangshen Jiang Xiaosa Xu Yuqian Qiu Prof. Xiaoming Liu Prof. Hongqiang Wang Prof. Stefan Kaskel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19628-19635
The development of ultrastable carbon materials for potassium storage poses key limitations caused by the huge volume variation and sluggish kinetics. Nitrogen-enriched porous carbons have recently emerged as promising candidates for this application; however, rational control over nitrogen doping is needed to further suppress the long-term capacity fading. Here we propose a strategy based on pyrolysis–etching of a pyridine-coordinated polymer for deliberate manipulation of edge-nitrogen doping and specific spatial distribution in amorphous high-surface-area carbons; the obtained material shows an edge-nitrogen content of up to 9.34 at %, richer N distribution inside the material, and high surface area of 616 m2 g−1 under a cost-effective low-temperature carbonization. The optimized carbon delivers unprecedented K-storage stability over 6000 cycles with negligible capacity decay (252 mA h g−1 after 4 months at 1 A g−1), rarely reported for potassium storage. 相似文献
104.
采用失重法、电化学法、X射线光电子能谱(XPS)和扫描电子显微镜(SEM)研究了0.5 mol/L NaCl溶液中,山梨酸钾(PS)与Zn2+对Q235钢的缓蚀协同效应。 失重实验结果表明,在0.5 mol/L NaCl溶液中,PS对Q235钢具有一定的缓蚀效果,缓蚀效率随PS质量浓度的增加而增大,当添加PS的质量浓度为25.0 g/L时,最大缓蚀效率仅为38.37%,而PS与Zn2+复配后存在显著的缓蚀协同作用,缓蚀效率高达91.03%。 动电势极化结果表明,PS与Zn2+混合物可同时抑制Q235钢的阴、阳极反应,属于阳极型缓蚀剂。 阻抗谱表明,该混合物可在电极表面形成致密的保护膜。 XPS分析证明保护膜是由PS、铁的氧化物/氢氧化物和Zn(OH)2沉淀组成。 相似文献
105.
高锰酸钾作为常用的氧化剂,其氧化性强弱与体系酸碱性相关。通过手持技术,利用氧化还原电势(ORP)传感器和pH传感器去探究体系酸碱性对高锰酸钾氧化性的影响。实验发现:pH在酸性条件下,高锰酸钾溶液的氧化性明显增强,随着体系pH的减小,氧化性继续增强;在碱性条件下,其氧化性明显减弱,随着体系pH的增大,其氧化性继续减弱。实际实验中需要根据各种综合因素选用适宜酸碱性的高锰酸钾溶液做氧化剂。 相似文献
106.
Ross F. Koby Alicia M. Doerr Nicholas R. Rightmire Nathan D. Schley Brian K. Long Timothy P. Hanusa 《Angewandte Chemie (International ed. in English)》2020,59(24):9542-9548
Milling two equivalents of K[1,3‐(SiMe3)2C3H3] (=K[A′]) with MgX2 (X=Cl, Br) produces the allyl complex [K2MgA′4] ( 1 ). Crystals grown from toluene are of the solvated species [((η6‐tol)K)2MgA′4] ([ 1 ?2(tol)]), a trimetallic monomer with both bridging and terminal (η1) allyl ligands. When recrystallized from hexanes, the unsolvated 1 forms a 2D coordination polymer, in which the Mg is surrounded by three allyl ligands. The C?C bond lengths differ by only 0.028 Å, indicating virtually complete electron delocalization. This is an unprecedented coordination mode for an allyl ligand bound to Mg. DFT calculations indicate that in isolation, an η3‐allyl configuration on Mg is energetically preferred over the η1‐ (σ‐bonded) arrangement, but the Mg must be in a low coordination environment for it to be experimentally realized. Methyl methacrylate is effectively polymerized by 1 , with activities that are comparable to K[A′] and greater than the homometallic magnesium complex [{MgA′2}2]. 相似文献
107.
Xinsheng Liu Lei Zhao Bin Miao Zhiqi Gu Jin Wang Huoxiang Peng Jiande Li Wei Sun Jiadong Li 《Electroanalysis》2020,32(2):422-428
Biosensors based on field‐effect transistor (FET) structures have attracted considerable attention because they offer rapid, inexpensive parallel sensing and ultrasensitive label‐free detection. However, long‐term repeatable detection cannot be performed, and Ag/AgCl reference electrode design is complicated, which has hindered FET biosensors from becoming truly wearable health‐monitoring platforms. In this paper, we propose a novel wearable detection platform based on AlGaN/GaN high‐electron‐mobility transistors (HEMTs). In this platform, a sweatband was used to continuously collect sweat, and a pH detecting unit and a potassium ion detecting unit were formed by modifying different sensitive films to realize the long‐term stable and repeatable detection of pH and potassium ions. Experimental data show that the wearable detection platform based on AlGaN/GaN HEMTs has good sensitivity (pH 3–7 sensitivity is 45.72 μA/pH; pH 7.4–9 sensitivity is 51.073 μA/pH; and K+ sensitivity is 4.94 μA/lgαK+), stability (28 days) and repeatability (the relative standard deviation (RSD) of pH 3–7 sensitivity is 2.6 %, the RSD of pH 7.4–9 sensitivity is 2.1 %, and the RSD of K+ sensitivity is 7.3 %). Our newly proposed wearable platform has excellent potential for predictive analytics and personalized medical treatment. 相似文献
108.
Johannes H. Harenberg Niels Weidmann Paul Knochel 《Angewandte Chemie (International ed. in English)》2020,59(30):12321-12325
We report the preparation of lithium‐salt‐free KDA (potassium diisopropylamide; 0.6 m in hexane) complexed with TMEDA (N,N,N′,N′‐tetramethylethylenediamine) and its use for the flow‐metalation of (hetero)arenes between ?78 °C and 25 °C with reaction times between 0.2 s and 24 s and a combined flow rate of 10 mL min?1 using a commercial flow setup. The resulting potassium organometallics react instantaneously with various electrophiles, such as ketones, aldehydes, alkyl and allylic halides, disulfides, Weinreb amides, and Me3SiCl, affording functionalized (hetero)arenes in high yields. This flow procedure is successfully extended to the lateral metalation of methyl‐substituted arenes and heteroaromatics, resulting in the formation of various benzylic potassium organometallics. A metalation scale‐up was possible without further optimization. 相似文献
109.
Zhantao Peng Bin Di Wentao Li Dan Liu Xiaojie Wen Hao Zhu Huanjun Song Yajie Zhang Cen Yin Xiong Zhou Kai Wu 《Angewandte Chemie (International ed. in English)》2020,59(34):14321-14325
Potassium (K) cations are spontaneously formed upon thermal deposition of low‐coverage K onto an ultrathin CuO monolayer grown on Cu(110) and they were explored by low‐temperature scanning tunneling microscopy (STM) and X‐ray photoemission spectroscopy. The formed K cations are highly immobile and thermally stable. The local work function around an individual K cation decreases by 1.5±0.3 eV, and a charging zone underneath it is established within about 1.0 nm. The cationic and neutral states of the K atom are switchable upon application of an STM bias voltage pulse, which is simultaneously accompanied by an adsorption site relocation. 相似文献
110.
A. M. Santos Ph. Vindevoghel C. Graillat A. Guyot J. Guillot 《Journal of polymer science. Part A, Polymer chemistry》1996,34(7):1271-1281
Two methods of analysis, potentiometry and capillary electrophoresis, were used to study the decomposition of potassium persulfate (KPS) in aqueous solutions. The experiments were carried out in a glass reactor equipped with continuous control of temperature and pH during the reaction. The effect of the pH on the decomposition of KPS was investigated. The rate of KPS decomposition in the presence of a variety of additives (surfactants, inhibitor, monomer-like molecules, and monomers), which are used in emulsion polymerization recipes, was also studied over the temperature range of interest. The rate of disappearance of the persulfate ion was greatly increased in the presence of hydroquinone, but changed very little in the presence of surfactants. © 1996 John Wiley & Sons, Inc. 相似文献