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51.
Ke Xu Evan T. Vickers Longshi Rao Dr. Sarah A. Lindley A'Lester C. Allen Prof. Binbin Luo Prof. Xueming Li Prof. Jin Zhong Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(19):5014-5021
CH3NH3PbBr3 perovskite quantum dots (PQDs) are synthesized by using four different linear alkyl phosphonic acids (PAs) in conjunction with (3-aminopropyl)triethoxysilane (APTES) as capping ligands. The resultant PQDs are characterized by means of XRD, TEM, Raman spectroscopy, FTIR spectroscopy, UV/Vis, photoluminescence (PL), time-resolved PL, and X-ray photoelectron spectroscopy (XPS). PA chain length is shown to control the PQD size (ca. 2.9–4.2 nm) and excitonic absorption band positions (λ=488–525 nm), with shorter chain lengths corresponding to smaller sizes and bluer absorptions. All samples show a high PL quantum yield (ca. 46–83 %) and high PL stability; this is indicative of a low density of band gap trap states and effective surface passivation. Stability is higher for smaller PQDs; this is attributed to better passivation due to better solubility and less steric hindrance of the shorter PA ligands. Based on the FTIR, Raman, and XPS results, it is proposed that Pb2+ and CH3NH3+ surface defects are passivated by R−PO32− or R−PO2(OH)−, whereas Br− surface defects are passivated by R−NH3+ moieties. This study establishes the combination of PA and APTES ligands as a highly effective dual passivation system for the synergistic passivation of multiple surface defects of PQDs through primarily ionic bonding. 相似文献
52.
Jia-Bin Han Ao Guo Prof. Xiang-Ying Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):2989-2994
A challenging deoxygenation of alkoxyl radicals from readily accessible alcohol derivatives was developed, affording facile synthesis of functionalized alkenes with good functional group tolerance under mild reaction conditions. Because alkoxyl radicals can easily undergo β-fragmentations or hydrogen abstractions, this new strategy for deoxygenation of alkoxyl radicals is highly valuable. Moreover, mechanistic studies revealed that the electron-neutral phosphine acts as the deoxygenation reagent. 相似文献
53.
Jiatian Chen Le Yang Ying Li Qinghua Hou Lanlan Li Peng Jin 《International journal of quantum chemistry》2019,119(16):e25961
Inorganic planar ring-shape molecules with 4n + 2 π electrons are always the focus of experimental synthesis and theoretical research due to their potential aromaticity and stability. In this work, the whole series of five-membered heterocycle monoanions X nY5-n− (X, Y = group 15 elements; n = 1-4) were thoroughly investigated by means of density functional theory calculations. They all have large formation energies and HOMO-LUMO gap energies, suggesting the potential thermodynamic and kinetic stability. Their aromaticities are comparable to that of typical aromatic hydrocarbons. Their thermal stabilities were firmly established by the ab initio molecular dynamics simulations. As most of them are predicted for the first time, their various spectra were simulated for experimental characterization. Furthermore, we demonstrate that these five-membered cyclic anions can be employed as η5-ligand to construct novel all-inorganic metallocenes, which may serve as the building blocks of low-dimensional nanomaterials. 相似文献
54.
Zhipeng Lin Hao Zhang Guofeng Liang Yanqi Jin Hongbin Zeng Jiawang Li Jian Chen Weihong Zhang Fangyan Xie Yanshuo Jin Hui Meng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):3112-3118
A composite of FeOOH nanocubes anchored on carbon ribbons has been synthesized and used as a cathode material for Li/O2 batteries. Fe2+ ion-exchanged resin serves as a precursor for both FeOOH nanocubes and carbon ribbons, which are formed simultaneously. The as-prepared FeOOH cubes are proposed to have a core–shell structure, with FeOOH as the shell and Prussian blue as the core, based on information from XPS, TEM, and EDS mapping. As a cathode material for Li/O2 batteries, FeOOH delivers a specific capacity of 14816 mA h g−1cathode with a cycling stability of 67 cycles over 400 h. The high performance is related to the low overpotential of the oxygen reduction/evolution reaction on FeOOH. The cube structure, the supporting carbon ribbons, and the -OOH moieties all contribute to the low overpotential. The discharge product Li2O2 can be efficiently decomposed in the FeOOH cathode after a charging process, leading to higher cycling stability. Its high activity and stability make FeOOH a good candidate for use in non-aqueous Li/O2 batteries. 相似文献
55.
Xiaoyu Ding Dr. Zhenghui Pan Na Liu Linge Li Xianshu Wang Guoguang Xu Jie Yang Jin Yang Nengsheng Yu Meinan Liu Prof. Wanfei Li Prof. Yuegang Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(15):3775-3780
Flexible lithium/sulfur (Li/S) batteries are promising to meet the emerging power demand for flexible electronic devices. The key challenge for a flexible Li/S battery is to design a cathode with excellent electrochemical performance and mechanical flexibility. In this work, a flexible strap-like Li/S battery based on a S@carbon nanotube/Pt@carbon nanotube hybrid film cathode was designed. It delivers a specific capacity of 1145 mAh g−1 at the first cycle and retains a specific capacity of 822 mAh g−1 after 100 cycles. Moreover, the flexible Li/S battery retains stabile specific capacity and Coulombic efficiency even under severe bending conditions. As a demonstration of practical applications, an LED array is shown stably powered by the flexible Li/S battery under flattened and bent states. We also use the strap-like flexible Li/S battery as a real strap for a watch, which at the same time provides a reliable power supply to the watch. 相似文献
56.
Bei-Bei Guo Dr. Yue-Jian Lin Prof. Guo-Xin Jin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(41):9721-9727
Four flexible ligands with different lengths, degrees of flexibility, and steric bulk were synthesized and used to prepare metal-directed assemblies. Interestingly, minor differences among the ligands led to products with dramatically different topologies: a binuclear D -shaped macrocycle, tetranuclear rectangles, and hexanuclear trefoil knots. The interconversion of the trefoil-shaped complexes was also investigated. This contribution introduces a rare ligand-controlled trefoil–rectangle shape transformation in solution. 相似文献
57.
A high‐performance liquid chromatography–tandem mass spectrometry method was developed and validated for the simultaneous quantification of morphine, morphine's major metabolites morphine‐3‐glucuronide and morphine‐6‐glucuronide, and clonidine, to support the pharmacokinetic analysis of an ongoing double‐blinded randomized clinical trial that compares the use of morphine and clonidine in infants diagnosed with neonatal abstinence syndrome. Plasma samples were processed by solid‐phase extraction and separated on an Inertsil ODS‐3 (4 μm) column using an 0.1% formic acid in water–0.1% formic acid in methanol gradient. Detection of the analytes was conducted in the positive multiple reaction monitoring mode. The range of quantitation was 1–1000 ng/mL for morphine, morphine‐3‐glucuronide and morphine‐6‐glucuronide, and 0.25–100 ng/mL for clonidine. Intra‐day and inter‐day accuracy and precision were ≤15% for all analytes across the quantitation range. Extraction recovery rates were ≥94% for morphine, ≥90% for M3G, ≥87% for M6G and ≥ 79% for clonidine. Matrix effect ranged from 85–94% for clonidine to 101–106% for M3G. The method fulfilled all predetermined acceptance criteria and required only 100 μL of starting plasma volume. Furthermore, it was successfully applied to 30 clinical trial plasma samples. 相似文献
58.
In this paper, we give interior gradient and Hessian estimates for systems of semi-linear degenerate elliptic partial differential equations on bounded domains, using both tools of backward stochastic differential equations and quasi-derivatives. 相似文献
59.
Xuejiao Hu Tiancheng Li Yidan Tang Yirong Wang Dr. Ao Wang Dr. Gengtao Fu Prof. Xiaodong Li Prof. Yawen Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(31):7561-7568
The development of high-efficiency electrocatalysts with low costs for the oxygen evolution reaction (OER) is essential, but remains challenging. Herein, a new synthetic process is proposed to prepare Ni3S4 particles embedded in N,P-codoped honeycomb porous carbon aerogels (Ni3S4/N,P-HPC) through a hydrogel approach. The preparation of Ni3S4/N,P-HPC begins with the sol–gel polymerization of tripolyphosphate, chitosan, and guanidine polymer that contains metal-binding sites, allowing for the uniform incorporation of Ni ions into the gel matrix, freeze-drying, and subsequent carbonization under an inert atmosphere. This synthesis resolves difficulties in synthesizing the pure Ni3S4 phase caused by the instability of Ni3S4 at high temperature, while affording good control of the porous structure and N,P-doping of carbon aerogels. The synergy between the structural advantages of N,P-carbon aerogels (such as easily accessible active sites, high specific surface area, and excellent electron transport) and the intrinsic electrochemical properties of Ni3S4 result in the outstanding OER performance of Ni3S4/N,P-HPC, with overpotentials as low as 0.37 V at 10 mA cm−2. The work outlined herein offers a simple and effective method for the development of carbon-based electrocatalysts for renewable energy conversion. 相似文献
60.
A series of 3-perfluoroalkylbenzoate esters are synthesised. They tend to exhibit enantiotropic SmA and SmC phases. The clearing points are decreased with increasing the alkoxy chain length and show odd-even effect. With increasing the fluorocarbon chain length, the melting and clearing points increase; however, the SmC phase is suppressed. 相似文献