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排序方式: 共有463条查询结果,搜索用时 31 毫秒
451.
Dr. Yetsedaw A. Tsegaw Dr. Hongmin Li Prof. em. Dr. Dr. h. c. Lester Andrews Prof. Dr. Han-Gook Cho Patrick Voßnacker Dr. Helmut Beckers Prof. Dr. Sebastian Riedel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(5):e202103142
An investigation of pulsed-laser-ablated Zn, Cd and Hg metal atom reactions with HCN under excess argon during co-deposition with laser-ablated Hg atoms from a dental amalgam target also provided Hg emissions capable of photoionization of the CN photo-dissociation product. A new band at 1933.4 cm−1 in the region of the CN and CN+ gas-phase fundamental absorptions that appeared upon annealing the matrix to 20 K after sample deposition, and disappeared upon UV photolysis is assigned to (Ar)nCN+, our key finding. It is not possible to determine the n coefficient exactly, but structure calculations suggest that one, two, three or four argon atoms can solvate the CN+ cation in an argon matrix with C−N absorptions calculated (B3LYP) to be between 2317.2 and 2319.8 cm−1. Similar bands were observed in solid krypton at 1920.5, in solid xenon at 1935.4 and in solid neon at 1947.8 cm−1. H13CN reagent gave an 1892.3 absorption with shift instead, and a 12/13 isotopic frequency ratio–nearly the same as found for 13CN+ itself in the gas phase and in the argon matrix. The CN+ molecular ion serves as a useful infrared probe to examine Ng clusters. The following ion reactions are believed to occur here: the first step upon sample deposition is assisted by a focused pulsed YAG laser, and the second step occurs on sample annealing: (Ar)2++CN→Ar+CN+→(Ar)nCN+. 相似文献
452.
A concise, straightforward and efficient method has been developed for the synthesis of α-aminonitriles by an one-pot three-component condensation of aldehydes or ketones, amines and trimethylsilyl cyanide catalyzed by MgI2 etherate under solvent-free conditions. This protocol has some advantages such as mild reaction condition, simple work-up, short reaction time and high product yields. 相似文献
453.
Kevin Blsing Jrg Harloff Axel Schulz Alrik Stoffers Philip Stoer Alexander Villinger 《Angewandte Chemie (International ed. in English)》2020,59(26):10508-10513
Although pure hydrogen cyanide can spontaneously polymerize or even explode, when initiated by small amounts of bases (e.g. CN?), the reaction of liquid HCN with [WCC]CN (WCC=weakly coordinating cation=Ph4P, Ph3PNPPh3=PNP) was investigated. Depending on the cation, it was possible to extract salts containing the formal dihydrogen tricyanide [CN(HCN)2]? and trihydrogen tetracyanide ions [CN(HCN)3]? from liquid HCN when a fast crystallization was carried out at low temperatures. X‐ray structure elucidation revealed hydrogen‐bridged linear [CN(HCN)2]? and Y‐shaped [CN(HCN)3]? molecular ions in the crystal. Both anions can be considered members of highly labile cyanide‐HCN solvates of the type [CN(HCN)n]? (n=1, 2, 3 …) as well as formal polypseudohalide ions. 相似文献
454.
Ujjal Haldar Rini Sharma Eun-Jae Kim Hyung-Il Lee 《Journal of polymer science. Part A, Polymer chemistry》2020,58(1):124-131
A water-soluble polymeric probe was designed and synthesized that can be used for the colorimetric selective detection of cyanide ions in pure aqueous media. In particular, P1, a water-soluble random terpolymer (P1) of N,N′-dimethylacrylamide, 2-((E)-4-((E)-(4-((2-(acryloyloxy)ethyl)(methyl)amino)phenyl)diazenyl)styryl)-1,3,3-trimethyl-3H-indol-1-ium (M1), and N-(4-benzoylphenyl)acrylamide was synthesized via traditional free-radical polymerization. Upon the addition of CN− ions to a P1 solution, a macroscopically detectable color change of the solution from brick red to light yellow took place, which was associated with a low limit of analyte detection (1.23 μM). Notably, P1 exhibited excellent selectivity toward CN− over other anions and biothiols, which may be present in the medium. Such highly selective colorimetric response to CN− by P1 originated from the nucleophilic attack of CN− anions onto the electron-deficient polarized CN bonds of P1's indolium moieties, resulting in the perturbation of the intramolecular charge transfer process occurring within the probe via destruction of the polymer's extended π-conjugation. P1 was also immobilized on a quartz slide by spin coating and then exposed to ultraviolet light. The resulting polymeric film displayed a rapid response to CN− consisting in a distinct color change, extending the scope of the usefulness of P1 as a cyanide-ion probe beyond the solution phase. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 124–131 相似文献
455.
Alexandre Genoux Jorge A. Gonzlez Estíbaliz Merino Cristina Nevado 《Angewandte Chemie (International ed. in English)》2020,59(41):17881-17886
A new family of phosphine‐ligated dicyanoarylgold(III) complexes has been prepared and their reactivity towards reductive elimination has been studied in detail. Both, a highly positive entropy of activation and a primary 12/13C KIE suggest a late concerted transition state while Hammett analysis and DFT calculations indicate that the process is asynchronous. As a result, a distinct mechanism involving an asynchronous concerted reductive elimination for the overall C(sp2)?C(sp)N bond forming reaction is characterized herein, for the first time, complementing previous studies reported for C(sp3)?C(sp3), C(sp2)?C(sp2), and C(sp3)?C(sp2) bond formation processes taking place on gold(III) species. 相似文献
456.
Dr. Graham N. Newton Dr. Kiyotaka Mitsumoto Rong‐Jia Wei Fumichika Iijima Dr. Takuya Shiga Prof. Dr. Hiroyuki Nishikawa Prof. Dr. Hiroki Oshio 《Angewandte Chemie (International ed. in English)》2014,53(11):2941-2944
A bulky bidentate ligand was used to stabilize a macrocyclic [FeIII8CoII6] cluster. Tuning the basicity of the ligand by derivatization with one or two methoxy groups led to the isolation of a homologous [FeIII8CoII6] species and a [FeIII6FeII2CoIII2CoII2] complex, respectively. Lowering the reaction temperatures allowed isolation of [FeIII6FeII2CoIII2CoII2] clusters with all three ligands. Temperature‐dependent absorption data and corresponding experiments with iron/nickel systems indicated that the iron/cobalt self‐assembly process was directed by the occurrence of solution‐state electron‐transfer‐coupled spin transition (ETCST) and its influence on reaction intermediate lability. 相似文献
457.
Valter Castelvetro Mustapha RaihaneSabrina Bianchi Salima AtlasIlaria Bonaduce 《Polymer Degradation and Stability》2011,96(2):204-211
The thermal decomposition under non-oxidative conditions of a copolymer of vinylidene cyanide (VCN) and 2,2,2-trifluoroethyl methacrylate (MATRIF) was investigated by thermogravimetry (TG) and Pyrolysis-GC-MS. The type and composition of the pyrolytic products and the shape of the TG curve indicate that both the main thermal degradation process, with onset at 368 °C, and a minor weight loss at around 222 °C are mainly associated with random main-chain scission. The kinetic parameters were determined by means of dynamic and, in the case of the main degradation stage, also isothermal methods. The results obtained from the dynamic methods (Friedman, Flynn-Wall-Ozawa, and Kissinger, respectively) are in good agreement with those obtained from isothermal TG data. The activation energy was in the 177-213 kJ/mol range for the first stage, and 224-295 kJ/mol for the second stage, the highest respective values being determined from the kinetic analysis according to the Kissinger method. 相似文献
458.
Guang‐Yue Li Guang‐Jiu Zhao Ke‐Li Han Guo‐Zhong He 《Journal of computational chemistry》2011,32(4):668-674
Proton transfer (PT) and excited‐state PT process are proposed to account for the fluorescent sensing mechanism of a cyanide chemosensor, 8‐formyl‐7‐hydroxycoumarin. The time‐dependent density functional theory method has been applied to investigate the ground and the first singlet excited electronic states of this chemosensor as well as its nucleophilic addition product with cyanide, with a view to monitoring their geometries and spectrophotometrical properties. The present theoretical study indicates that phenol proton of the chemosensor transfers to the formyl group along the intramolecular hydrogen bond in the first singlet excited state. Correspondingly, the nucleophilic addition product undergoes a PT process in the ground state, and shows a similar structure in the first singlet excited state. This could explain the observed strong fluorescence upon the addition of the cyanide anion in the relevant fluorescent sensing mechanism. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011 相似文献
459.
CaO高温脱除氰化氢试验研究 总被引:1,自引:0,他引:1
本文在石英反应器内试验了高温脱除HCN反应机理,研究了CaO对氰化氢的脱除作用,探讨了温度、体积空速和氰化氢浓度对脱除氰化氢的影响.试验结果表明:当T<45℃,CaO促使HCN中的N元素转化到CaCN_2,当T>800℃,CaO促使HCN中的N元素全部转化为N_2;CaO在800℃时,只要体积空速小于12000 h~(-1),CaO对HCN均有接近100%的脱除效果;在体积空速10000 h~(-1)、温度800℃工况下,CaO对初始浓度范围127×10~(-6)-512×10~(-6)的HCN均有接近100%的脱除效果. 相似文献
460.
Ying-Lian Qin Hong Sun Yan Jing Xiu-Ping Jiang Gao-Feng Wang Jian-Fang Qin 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(11):1517-1523
The cyanide ligand can act as a strong σ‐donor and an effective π‐electron acceptor that exhibits versatile bridging abilities, such as terminal, μ2‐C:N, μ3‐C:C:N and μ4‐C:C:N:N modes. These ligands play a key role in the formation of various copper(I) cyanide systems, including one‐dimensional (1D) chains, two‐dimensional (2D) layers and three‐dimensional (3D) frameworks. According to the literature, numerous coordination polymers based on terminal, μ2‐C:N and μ3‐C,C,N bridging modes have been documented so far. However, systems based on the μ4‐C:C:N:N bridging mode are relatively rare. In this work, a novel cyanide‐bridged 3D CuI coordination framework, namely poly[(μ2‐2,2′‐biimidazole‐κ2N3:N3′)(μ4‐cyanido‐κ4C:C:N:N)(μ2‐cyanido‐κ2C:N)dicopper(I)], [Cu2(CN)2(C6H6N4)]n, (I), was synthesized hydrothermally by reaction of environmentally friendly K3[Fe(CN)6], CuCl2·2H2O and 2,2′‐biimidazole (H2biim). It should be noted that cyanide ligands may act as reducing agents to reduce CuII to CuI under hydrothermal conditions. Compound (I) contains diverse types of bridging ligands, such as μ4‐C:C:N:N‐cyanide, μ2‐C:N‐cyanide and μ2‐biimidazole. Interestingly, the [Cu2] dimers are bridged by rare μ4‐C:C:N:N‐mode cyanide ligands giving rise to the first example of a 1D dimeric {[Cu2(μ4‐C:C:N:N)]n+}n infinite chain. Furthermore, adjacent dimer‐based chains are linked by μ2‐C:N bridging cyanide ligands, generating a neutral 2D wave‐like (4,4) layer structure. Finally, the 2D layers are joined together via bidentate bridging H2biim to create a 3D cuprous cyanide network. This arrangement leads to a systematic variation in dimensionality from 1D chain→2D sheet→3D framework by different types of bridging ligands. Compound (I) was further characterized by thermal analysis, solid‐state UV–Vis diffuse‐reflectance and photoluminescence studies. The solid‐state UV–Vis diffuse‐reflectance spectra show that compound (I) is a wide‐gap semiconductor with band gaps of 3.18 eV. The photoluminescence study shows a strong blue–green photoluminescence at room temperature, which may be associated with metal‐to‐ligand charge transfer. 相似文献