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911.
2.5次微分溶出伏安法同时测定人脑中铜,铅,镉,锌 总被引:3,自引:0,他引:3
本文通过硝酸-硫酸混合酸消化脑样,在0.03mol/LHClO4底液中,采用悬汞电极2.5次微分阳极溶出伏安法同时测定人脑中铜、铅、镉、锌四种微量元素。在选定的实验条件下,所述元素的浓度在5~100ng/mL范围内与峰高成线性关系。用于人脑中铜、铅、镉和锌的分析,其相对标准偏差分别为6.5%、10.5%、12.7%和3.1%,其回收率为98.0%、94.0%、102.0%和104.0%。 相似文献
912.
Synthesis of linear and star‐like poly(ε‐caprolactone)‐b‐poly{γ‐2‐[2‐(2‐methoxy‐ethoxy)ethoxy]ethoxy‐ε‐caprolactone} amphiphilic block copolymers using zinc undecylenate
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Katherine E. Washington Ruvanthi N. Kularatne Jia Du Matthew J. Gillings Jack C. Webb Nicolette C. Doan Michael C. Biewer Mihaela C. Stefan 《Journal of polymer science. Part A, Polymer chemistry》2016,54(22):3601-3608
Linear and star‐like amphiphilic diblock copolymers were synthesized by the ring‐opening polymerization of ε‐caprolactone and γ‐2‐[2‐(2‐methoxyethoxy)ethoxy]ethoxy‐ε‐caprolactone monomers using zinc undecylenate as a catalyst. These polymers have potential applications as micellar drug delivery vehicles, therefore the properties of the linear and 4‐arm star‐like structures were examined in terms of their molecular weight, viscosity, thermodynamic stability, size, morphology, and drug loading capacity. Both the star‐like and linear block copolymers showed good thermodynamic stability and degradability. However, the star‐like polymers were shown to have increased stability at lower concentrations with a critical micelle concentration (CMC) of 5.62 × 10?4 g L?1, which is less than half the concentration of linear polymer needed to form micelles. The star‐like polymeric micelles showed smaller sizes when compared with their linear counterparts and a higher drug loading capacity of doxorubicin, making them better suited for drug delivery purposes. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3601–3608 相似文献
913.
Jean-Noël Rebilly 《Supramolecular chemistry》2014,26(7-8):454-479
Metallo-enzymes are natural catalysts carrying out highly selective and demanding reactions under mild conditions, using readily available metal ions (iron, copper, zinc, etc.). Understanding the factors explaining these performances is thus of fundamental and applicative interest. Classical model complexes displaying significant limitations in reactivity led to the development of supramolecular systems associating a reactive complex to a molecular cavity receptor, in order to not only mimic the first coordination sphere of the metal, but also the supramolecular enzymatic environment (access channel and binding pocket) responsible for their remarkable kinetics and selectivities. Calixarenes and resorcinarenes are particularly suited to this goal due to their wide range of sizes and flexibility. This review illustrates several specific aspects of enzymatic systems that were successfully mimicked with such supramolecular model systems. This toolbox of supramolecular effects could be used for future developments of bioinorganic supramolecular catalysts. 相似文献
914.
New 3 D Tubular Porous Structure of an Organic–Zincophosphite Framework with Interesting Gas Adsorption and Luminescence Properties
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Prof. Chih‐Min Wang Dr. Li‐Wei Lee Tsung‐Yuan Chang Bing‐Lun Fan Chih‐Ling Wang Prof. Hsiu‐Mei Lin Prof. Kuang‐Lieh Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16099-16102
A new 3D tubular zinc phosphite, Zn2(C22H22N8)0.5(HPO3)2?H2O ( 1 ), incorporating a tetradentate organic ligand was synthesized under hydro(solvo)thermal conditions and structurally characterized by single‐crystal X‐ray diffraction. Compound 1 is the first example of inorganic zincophosphite chains being interlinked through 1,2,4,5‐tetrakis(imidazol‐1‐ylmethyl)benzene to form a tubular porous framework with unusual organic–inorganic hybrid channels. The thermal and chemical stabilities, high capacity for CO2 adsorption compared to that for N2 adsorption, and interesting optical properties of LED devices fabricated using this compound were also studied. 相似文献
915.
Directly 2,12‐ and 2,8‐Linked ZnII Porphyrin Oligomers: Synthesis,Optical Properties,and Coherence Lengths
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Dr. Hua‐Wei Jiang Taeyeon Kim Dr. Takayuki Tanaka Prof. Dr. Dongho Kim Prof. Dr. Atsuhiro Osuka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):83-87
Directly 2,12‐ and 2,8‐linked ZnII porphyrin oligomers were prepared from 2,12‐ and 2,8‐diborylated ZnII porphyrin by a cross platinum‐induced coupling with a 2‐borylated ZnII porphyrin end unit followed by a triphenylphosphine (PPh3)‐mediated reductive elimination. Comparative studies on the steady‐state absorption and fluorescence spectra and the fluorescence lifetimes led to a conclusion that the exciton in the S1 state is delocalized over approximately four and two ZnII porphyrin units for 2,12‐ and 2,8‐linked ZnII porphyrin arrays, respectively. 相似文献
916.
917.
Michał Padjasek Dr. Maciej Maciejczyk Dr. Michał Nowakowski Olga Kerber Maciej Pyrka Prof. Dr. Wiktor Koźmiński Prof. Dr. Artur Krężel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(15):3297-3313
CdII is a major genotoxic agent that readily displaces ZnII in a multitude of zinc proteins, abrogates redox homeostasis, and deregulates cellular metalloproteome. To date, this displacement has been described mostly for cysteine(Cys)-rich intraprotein binding sites in certain zinc finger domains and metallothioneins. To visualize how a ZnII-to-CdII swap can affect the target protein's status and thus understand the molecular basis of CdII-induced genotoxicity an intermolecular ZnII-binding site from the crucial DNA repair protein Rad50 and its zinc hook domain were examined. By using a length-varied peptide base, ZnII-to-CdII displacement in Rad50’s hook domain is demonstrated to alter it in a bimodal fashion: 1) CdII induces around a two-orders-of-magnitude stabilization effect (log =20.8 vs. log =22.7), which defines an extremely high affinity of a peptide towards a metal ion, and 2) the displacement disrupts the overall assembly of the domain, as shown by NMR spectroscopic and anisotropy decay data. Based on the results, a new model explaining the molecular mechanism of CdII genotoxicity that underlines CdII’s impact on Rad50’s dimer stability and quaternary structure that could potentially result in abrogation of the major DNA damage response pathway is proposed. 相似文献
918.
A green approach is reported for the synthesis of cysteine-functionalized zinc oxide nanoparticles using potato extract as a nontoxic and economical reducing agent. The cysteine-functionalized nanoparticles were used as a support for enzyme immobilization. The structural morphology, crystallinity, and surface functionalization were characterized by scanning electron microscopy, X-ray diffraction, and infrared spectroscopy, respectively. Spherical nanoparticles from 150 to 200?nm were used to evaluate the immobilization efficiency for urease through covalent attachment on the glutaraldehyde-activated amino group of cysteine. In comparison to the unmodified nanoparticles, 62.9% enzyme loading with 72.45% of enzyme specific activity was recovered which was 56% higher than on bare zinc oxide nanoparticles. The point of addition of cysteine during the nanoparticle synthesis had a direct effect on the immobilization efficiency. The immobilized enzyme-specific activity was reduced to 34.32% when cysteine was added following the nanoparticle synthesis. With a facile synthesis procedure and significant immobilization efficiency, cysteine-functionalized zinc oxide nanoparticles were shown to be suitable for various clinical and industrial applications. 相似文献
919.
Manoj Kumar Yadav Akhilendra Kumar Maurya Gunjan Rajput Krishna Kumar Manar Manjula Vinayak Michael G. B. Drew 《Journal of Coordination Chemistry》2017,70(18):3171-3185
New homoleptic zinc(II) complexes, [Zn(L)2], where L = methyl-3-hydroxy-(3-pyridyl)-2-propenedithioate L1 1, and methyl-3-hydroxy-(4-pyridyl)-2-propenedithioate L2 2, have been synthesized and characterized by elemental (C, H, and N) analysis, ESI-MS, and (IR, UV–vis, NMR) spectroscopy; the structure of 1 has been deduced by X-ray crystallography. The DNA binding and cleavage activity of the complexes have been studied. The cleavage potential of pBR322 DNA by 1 and 2 has been checked. Complex 1, which contains nitrogen of the pyridine group in the 3-position enhances DNA cleavage potential in the presence of ascorbic acid; however, the complex is protective against DNA cleavage in the presence of DMSO or H2O2. Also, 1 causes cytotoxicity against the MCF-7 breast cancer cell line. The efficient cytotoxic activity and DNA cleavage ability of 1 in the presence of ascorbic acid shows its potential anticancer properties and the need for further investigations of its potential as an anticancer drug. 相似文献
920.