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1.
Novel processes have recently been developed that provide for the enhancement of ozonation through combination with electrochemical treatments. These are processes that can be included among those defined as advanced oxidation processes as they proceed via electrogeneration of highly oxidizing radical species.These processes are generally carried out by sparging ozone in both divided and undivided electrochemical cells in order to promote its decomposition through different mechanisms, depending on the electrode materials adopted, and in some cases still debated.This mini review presents the most recent advances in the field of electrochemically assisted ozonation.In particular, the first section is focused on the process known as electroperoxone (EP) where the ozone decomposition is enhanced by the adoption of carbon-based cathodes, due to the electrogeneration of hydrogen peroxide, while the second section is focused on the process that implies ozonation in a cell adopting metal-based cathodes. 相似文献
2.
碳基材料催化剂因具有良好的催化性能,同时可避免金属催化剂的重金属沥出造成的二次污染问题,常被应用于高级氧化领域。其中,以废弃生物质为原材料热解产生的生物炭,不仅具有催化潜力,还具有低成本和绿色环保等优势,被广泛用于活化过氧化氢、过一硫酸氢盐和过二硫酸盐等过氧化物降解水中有机污染物。本文介绍了生物炭的前体种类和制备方法、阐述了二者对生物炭活化能力的影响,总结了生物炭活化过氧化物的机理,分析了水质对降解污染物的影响,综述了生物炭的改性、循环使用及再生,指出了这一技术存在的问题并对后续研究进行了展望。 相似文献
3.
Exploring the discrete complexes with multi-step coloration is still a challenge in the field of electron transfer photochromic materials. Herein, we synthesized a series of dinuclear Ln-diphosphonate compounds[Ln=Dy(1); Gd(2); Tb(3); Y(4)] with a remarkably and reversibly photoactive coloration phenomenon. These compounds showed two-step coloration behavior, which were the first discrete architectures in the reported electron transfer photochromic complexes. This two-step coloration phenomenon was originated from the large distortion of H3-TPT acceptors, which in turn reduced the π-conjugation of electron acceptors and slowed the decay process of electron transfer. The photogenerated stable doublet radicals originated from electron transfer from diphosphonate donor to polypyridine acceptor in these complexes were detected by UV-Vis and electron spin resonance(ESR) spectra. Furthermore, the photogenerated radicals were estimated by direct current magnetic susceptibilities and variable temperature ESR spectra, suggesting the doublet radicals in the dinuclear structure for all the compounds. This work revealed a series of discrete phosphonate-based systems with a multi-step coloration process, providing a new pathway for designing multicolor photochromic materials with potential photoswitching or other applications. 相似文献
4.
为得到新型高效多相催化剂,有效去除废水中的染料,以Cu(Ac)_2与CuFe_2O_4@PDA为原料制备了催化剂CuFe_2O_4@PDA-Cu.通过IR、XRD、XPS、UV-Vis、DRS技术对催化剂的性能进行了表征,考察了温度、H_2O_2用量、催化剂用量、pH值、盐等对催化活性的影响.利用HPLC测定降解产物,采用自由基捕获和抑制实验进行机理验证,发现催化剂是核壳结构.温度升高、pH值升高、H_2O_2和催化剂用量的增加均有利于提高催化活性;氯化物、硫酸盐、硝酸盐和磷酸盐不影响催化效果,溴化物和亚硝酸盐降低了催化效果.得到的最优降解条件为:T=30℃,催化剂用量10mg·L~(-1),pH=9,过氧化氢用量10mmol·L~(-1),染料浓度30mg·L~(-1).最优条件下催化剂可循环使用4次以上;甲基橙、茜素红和罗丹明B的去除率为100%;染料R0213、O0118和B0115的去除率大于60%.降解产物有草酸、马来酸和CO_2.甲基橙、茜素红和罗丹明B降解后COD_(Mn)=2~4mg·L~(-1).水杨酸捕获·OH生成2.5-二羟基苯甲酸,叔丁醇抑制染料降解.结果表明,催化剂可活化H_2O_2产生·OH,·OH攻击染料分子开环降解直至矿化.该研究为开发高效多相催化剂,有效去除废水中的染料提供了科学依据. 相似文献
5.
N-杂环卡宾配体的优异催化性能引起了人们的广泛关注, 已成功应用于多种烯烃聚合反应。本文结合N-杂环卡宾的相关研究报道,首先简要介绍N-杂环卡宾,随后重点介绍N-杂环卡宾在开环易位聚合、烯烃配位聚合和原子转移自由基聚合等聚合反应的应用。在此基础上,指出了今后N-杂环卡宾配体在聚合反应研究的发展方向。 相似文献
6.
Eriko Sato Noboru Tamari Hideo Horibe 《Journal of polymer science. Part A, Polymer chemistry》2019,57(24):2474-2480
Graft copolymers show microphase separated structure as seen in block copolymers and have lower intrinsic viscosity than block copolymers because of a branching structure. Therefore, considering molding processability, especially for polymers containing rigid segments, graft copolymers are useful architectures. In this work, graft copolymers containing rigid poly(diisopropyl fumarate) (PDiPF) branches were synthesized by full free‐radical polymerization process. First, synthesis of PDiPF macromonomers by addition‐fragmentation chain transfer (AFCT) was investigated. 2,2‐Dimethyl‐4‐methylene‐pentanedioic acid dimethyl ester was found to be an efficient AFCT agent for diisopropyl fumarate (DiPF) polymerization because of the suppression of undesired primary radical termination, which significantly took place when common AFCT agent, methyl 2‐(bromomethyl)acrylate, was used. Copolymerization of PDiPF macromonomer with ethyl acrylate accomplished the generation of the graft copolymer having flexible poly(ethyl acrylate) backbone and rigid PDiPF branches. The graft copolymer showed a microphase separated structure, high transparency, and characteristic thermal properties to PDiPF and poly(ethyl acrylate). © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2474–2480 相似文献
7.
Ikhlas Gadwal Prakash P. Wadgaonkar Amol B. Ichake Shivshankar R. Mane 《Journal of polymer science. Part A, Polymer chemistry》2019,57(2):146-156
A new approach was developed for synthesis of certain A3B3‐type of double hydrophilic or amphiphilic miktoarm star polymers using a combination of “grafting onto” and “grafting from” methods. To achieve the synthesis of desired miktoarm star polymers, acetyl protected poly(ethylene glycol) (PEG) thiols (Mn = 550 and 2000 g mol?1) were utilized to generate A3‐type of homoarm star polymers through an in situ protective group removal and a subsequent thiol–epoxy “click” reaction with a tris‐epoxide core viz. 1,1,1‐tris(4‐hydroxyphenyl)ethane triglycidyl ether. The secondary hydroxyl groups generated adjacent to the core upon the thiol–epoxy reaction were esterified with α‐bromoisobutyryl bromide to install atom transfer radical polymerization (ATRP) initiating sites. ATRP of N‐isopropylacrylamide (NIPAM) using the three‐arm star PEG polymer fitted with ATRP initiating sites adjacent to the core afforded A3B3‐type of double hydrophilic (PEG)3[poly(N‐isopropylacrylamide)] (PNIPAM)3 miktoarm star polymers. Furthermore, the generated hydroxyl groups were directly used as initiator for ring‐opening polymerization of ε‐caprolactone to prepare A3B3‐type of amphiphilic (PEG)3[poly(ε‐caprolactone)]3 miktoarm star polymers. The double hydrophilic (PEG)3(PNIPAM)3 miktoarm star polymers showed lower critical solution temperature around 34 °C. The preliminary transmission electron microscopy analysis indicated formation of self‐assembly of (PEG)3(PNIPAM)3 miktoarm star polymer in aqueous solution. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 146–156 相似文献
8.
Wen Zhang Nailiang Zhu Meigeng Hu Shichun Yu Zhonghao Sun Haifeng Wu 《Natural product research》2019,33(4):500-505
Phytochemical investigation of the stem of Aralia chinensis yielded six new oleanane-type triterpene saponins named as congmujingnosides B-G (1–6). The new ones were elucidated on the basis of the chemical and spectroscopic analysis. Protective effects of compounds 1?6 were tested against H2O2-induced H9c2 cardiomyocyte injury, and the data showed that compounds 1 and 5 had significant cell-protective effects. No significant DPPH radical scavenging activity was observed for compounds 1?6. 相似文献
9.
AbstractThe reactions of methyl radicals with MII-(ntp)(H2O)2 complexes were studied. The formation of an unstable intermediate (ntp)(H2O)MIII-CH3 is observed. This reaction is an equilibrium process, i.e. the MIII-C bond decomposes via homolysis. The (ntp)(H2O)MIII-CH3 complexes isomerize to a more stable form. The results compared to those obtained in analogous reactions of the MII-(nta)(H2O)2 complexes were shown to be similar with one exception – for the nta complexes no isomerization process is observed. 相似文献
10.
Cyclic compounds constitute a great important class of substances in the science of medicine and biology, which renders the research on facile and efficient construction of such complex scaffolds from simple starting materials to be hot and appealing. Recently, the radical cascade reaction involving multiple bond formation/cleavage has emerged as an ideal and powerful route to give high‐value cyclic products, along with diminished cost and waste. As a simple and benign methodology, photoredox catalysis offers a readily available access to the generation of radical species. Alkenes have been recognized as one of the most valuable building blocks for the reason they allow installation of different functional groups simultaneously through addition to the C=C bonds. This account summarizes the recent advances in photoinduced radical cascade cyclization to the synthesis of cyclic compounds with C=C bonds working as the initial radical acceptors, and emphasis is put on the related reaction mechanisms. 相似文献