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951.
Br?nsted acid catalysts have been used in a number of organic transformations. To overcome limi‐tations, such as toxicity, volatility, high price and hazardous nature of the conventional methods, the c... 相似文献
952.
Bhagat Kavita Singh Jatinder V. Pagare Piyusha P. Kumar Nitish Sharma Anchal Kaur Gurinder Kinarivala Nihar Gandu Srinivasa Singh Harbinder Sharma Sahil Bedi Preet Mohinder S. 《Molecular diversity》2021,25(1):551-601
Molecular Diversity - GABA (γ-amino butyric acid) is an important inhibitory neurotransmitter in the central nervous system. Attenuation of GABAergic neurotransmission plays an important role... 相似文献
953.
Dr. Mandeep Kaur Dr. Noor U Din Reshi Kamaless Patra Arindom Bhattacherya Dr. Sooraj Kunnikuruvan Prof. Jitendra K. Bera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(41):10737-10748
A Cp*Ir(III) complex ( 1 ) of a newly designed ligand L1 featuring a proton-responsive pyridyl(benzamide) appended on N - heterocyclic carbene (NHC) has been synthesized. The molecular structure of 1 reveals a dearomatized form of the ligand. The protonation of 1 with HBF4 in tetrahydrofuran gives the corresponding aromatized complex [Cp*Ir(L1H)Cl]BF4 ( 2 ). Both compounds are characterized spectroscopically and by X-ray crystallography. The protonation of 1 with acid is examined by 1H NMR and UV-vis spectra. The proton-responsive character of 1 is exploited for catalyzing α-alkylation of ketones and β-alkylation of secondary alcohols using primary alcohols as alkylating agents through hydrogen-borrowing methodology. Compound 1 is an effective catalyst for these reactions and exhibits a superior activity in comparison to a structurally similar iridium complex [Cp*Ir(L2)Cl]PF6 ( 3 ) lacking a proton-responsive pendant amide moiety. The catalytic alkylation is characterized by a wide substrate scope, low catalyst and base loadings, and a short reaction time. The catalytic efficacy of 1 is also demonstrated for the syntheses of quinoline and lactone derivatives via acceptorless dehydrogenation, and selective alkylation of two steroids, pregnenolone and testosterone. Detailed mechanistic investigations and DFT calculations substantiate the role of the proton-responsive ligand in the hydrogen-borrowing process. 相似文献
954.
Bindu Rani Aadil Fayaz Wani Utkir Bahodirovich Sharopov Lokanath Patra Jaspal Singh Atif Mossad Ali A. F. Abd El-Rehim Shakeel Ahmad Khandy Shobhna Dhiman Kulwinder Kaur 《Molecules (Basel, Switzerland)》2022,27(19)
We hereby discuss the thermoelectric properties of PdXSn(X = Zr, Hf) half Heuslers in relation to lattice thermal conductivity probed under effective mass (hole/electrons) calculations and deformation potential theory. In addition, we report the structural, electronic, mechanical, and lattice dynamics of these materials as well. Both alloys are indirect band gap semiconductors with a gap of 0.91 eV and 0.82 eV for PdZrSn and PdHfSn, respectively. Both half Heusler materials are mechanically and dynamically stable. The effective mass of electrons/holes is (0.13/1.23) for Zr-type and (0.12/1.12) for Hf-kind alloys, which is inversely proportional to the relaxation time and directly decides the electrical/thermal conductivity of these materials. At 300K, the magnitude of lattice thermal conductivity observed for PdZrSn is 15.16 W/mK and 9.53 W/mK for PdHfSn. The highest observed ZT value for PdZrSn and PdHfSn is 0.32 and 0.4, respectively. 相似文献
955.
Jagjit Singh Dhaliwal Said Moshawih Khang Wen Goh Mei Jun Loy Md. Sanower Hossain Andi Hermansyah Vijay Kotra Nurolaini Kifli Hui Poh Goh Sachinjeet Kaur Sodhi Dhaliwal Hayati Yassin Long Chiau Ming 《Molecules (Basel, Switzerland)》2022,27(20)
Chalcones have been well examined in the extant literature and demonstrated antibacterial, antifungal, anti-inflammatory, and anticancer properties. A detailed evaluation of the purported health benefits of chalcone and its derivatives, including molecular mechanisms of pharmacological activities, can be further explored. Therefore, this review aimed to describe the main characteristics of chalcone and its derivatives, including their method synthesis and pharmacotherapeutics applications with molecular mechanisms. The presence of the reactive α,β-unsaturated system in the chalcone’s rings showed different potential pharmacological properties, including inhibitory activity on enzymes, anticancer, anti-inflammatory, antibacterial, antifungal, antimalarial, antiprotozoal, and anti-filarial activity. Changing the structure by adding substituent groups to the aromatic ring can increase potency, reduce toxicity, and broaden pharmacological action. This report also summarized the potential health benefits of chalcone derivatives, particularly antimicrobial activity. We found that several chalcone compounds can inhibit diverse targets of antibiotic-resistance development pathways; therefore, they overcome resistance, and bacteria become susceptible to antibacterial compounds. A few chalcone compounds were more active than conventional antibiotics, like vancomycin and tetracycline. On another note, a series of pyran-fused chalcones and trichalcones can block the NF-B signaling complement system implicated in inflammation, and several compounds demonstrated more potent lipoxygenase inhibition than NSAIDs, such as indomethacin. This report integrated discussion from the domains of medicinal chemistry, organic synthesis, and diverse pharmacological applications, particularly for the development of new anti-infective agents that could be a useful reference for pharmaceutical scientists. 相似文献
956.
A generalized matrix version of reverse Cauchy-Schwarz/Hölder inequality is proved. This includes the recent results proved by Bourin, Fujii, Lee, Niezgoda and Seo. 相似文献
957.
A. S. Brar Sukhdeep Kaur 《Journal of polymer science. Part A, Polymer chemistry》2005,43(5):1100-1118
Copolymers of methyl methacrylate (MMA) and n‐butyl acrylate (n‐BA) were synthesized under atom transfer radical polymerization (ATRP) conditions. The molar infeed ratio was varied to obtain copolymers with different compositions. Methyl 2‐bromo propionate was used as the initiator with CuBr/Cu(0)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalyst at 60 °C. Molecular weight distribution was determined by gel permeation chromatography (GPC). Copolymer compositions (FM) were calculated from 1H NMR spectra. Reactivity ratios calculated with the Mao–Huglin terminal model at a high conversion were found to be rM = 2.17 and rB = 0.47. The polymerization mechanism was studied with the α‐methyl region of MMA. The backbone methylene and carbonyl carbons of both MMA and n‐BA units were found to be compositionally as well as configurationally sensitive. Complete spectral assignments were performed with the help of heteronuclear single quantum coherence (HSQC) spectroscopy along with total correlated spectroscopy (TOCSY). Further, the assignments of the carbonyl region were made with the help of heteronuclear multiple quantum coherence (HMBC) spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1100–1118, 2005 相似文献
958.
Tarlok S Lobana Amarjeet Singh Mandeep Kaur Alfonso Castineiras 《Journal of Chemical Sciences》2001,113(2):89-94
Reaction of mercury(II) diiodide with triphenyl selenophosphorane-Se (1:1 mole ratio) in acetone followed by recrystallisation
of the product from chloroform formed crystals of stoichiometry HgI2(Ph3PSe)(1). Compound1 exists as a centrosymmetric homobimetallic dimer, Hg(Μ-I)I(Ph3PSe)2, as monoclinic crystals of space group P21/n. The dimer comprises two Μ2-iodo atoms that form unequal Hg-I bonds 2.8230(10), 3.1135(9) ? and two equal terminal Hg-I bonds 2.6524(10) ?. The Se atom
of Ph3PSe forms terminal Hg-Se bond 2.5914(11)? and thus the geometry about each Hg centre is distorted tetrahedral and the range
of tetrahedral bond angles is 92.97(2) to 130.85(3)‡, the largest being that of Se(1)-Hg(1)-I(1) and the shortest, I(2)-Hg(1)-I(2)‡.
Hg-Hg and I-I separations of 4.0930(11)? and 4.3097(15)? are more than the sums of their respective van der Waal radii 3.00
? and 4.24 ?. 相似文献
959.
Kiran Singh Rajneesh Mohan Nupinder Kaur N.K. Gaur Manglesh Dixit Vilas Shelke R.K. Singh 《Physica C: Superconductivity and its Applications》2006,450(1-2):124-128
The effects of Cu doping in MgB2 superconductor has been studied at different processing temperatures. The polycrystalline samples of Mg1−xCuxB2 with x = 0.05 were synthesized through the in-situ solid sate reaction method in argon atmosphere at different temperature range between 800–900 °C. The samples were characterized through X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and low temperature R–T measurement techniques for the phase verification, microstructure and superconducting transition temperature, respectively. The XRD patterns of Mg1−xCuxB2 (x = 0.05) do not exhibit any impurity traces of MgB4 or MgB6 and they show the sharp transition in the samples prepared at 850 °C. The onset transition temperature of the prepared samples is around 39 K, which is almost the same as that for the pure MgB2. This indicates that Cu doping in MgB2 does not affect the transition temperature. The SEM micrograph of Mg0.95Cu0.05B2 has shown that the sample is dense with grain size smaller than 1 μm. 相似文献
960.
Rakesh Kumar Mahajan Ravneet Kaur Inderpreet Kaur Vandana Sharma Manoj Kumar 《Analytical sciences》2004,20(5):811-814
A PVC membrane incorporating p-tert-butyl calix[4]crown with imine units as an ionophore was prepared and used in an ion-selective electrode for the determination of mercury(II) ions. An electrode based on this ionophore showed a good potentiometric response for mercury(II) ions over a wide concentration range of 5.0 x 10(-5) - 1.0 x 10(-1) M with a near-Nernstian slope of 27.3 mV per decade. The detection limit of the electrode was 2.24 x 10(-5) M and the electrode worked well in the pH range of 1.3 - 4.0. The electrode showed a short response time of less than 20 s. The electrode also showed better selectivity for mercury(II) ions over many of the alkali (Na+, -1.69; K+, -1.54), alkaline-earth (Ca2+, -3.30; Ba2+, -3.32), and heavy metal ions (Co2+, -3.67; Ni2+, -3.43; Pb2+, -3.31; Fe3+, -1.82). Ag+ ion was found to be the strongest interfering ion. Also, sharp end points were obtained when the sensor was used as an indicator electrode for the potentiometric titration of mercury(II) ions with iodide and dichromate ions. 相似文献