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951.
Tetrakis-4-(2,4-di-amylphenoxy) phthalocyaninato-polysiloxane (R1PcPS) Langmuir-Blodgett (LB) films were prepared onto planar interdigital microelectrode arrays and their pas sensitive, properties were investigated. The results of response and recovery process were Shown when the (R1PcPS) LB films were exposed to NH3, NO2 and I2 gas in air. THh gas sensitive sensor consisting of (R1PcPS) LB film can be used to detect NH3 gas down to 0.0005% in air. 相似文献
952.
使用浸渍法结合不同预处理方法制备了一系列的Ru/SBA-15催化剂,并将其应用于丙三醇氢解反应中.使用N2吸附-脱附、X射线衍射、CO化学吸附以及透射电子显微镜等方法对所制备Ru/SBA-15进行了表征.结果表明,催化剂前驱体经过空气焙烧后再经H2还原的Ru/SBA-15催化剂上Ru的分散度较低,而直接使用H2处理较高.同时,随着H2还原温度提高,Ru分散度逐渐降低.保持反应活性接近时,随着Ru分散度的降低,TOF增加.表明Ru/SBA-15催化剂上丙三醇氢解是结构敏感反应. 相似文献
953.
Dynamic covalent polypeptides showing tunable secondary structures and thermoresponsiveness 下载免费PDF全文
Jiatao Yan Kun Liu Xiuqiang Zhang Wen Li Afang Zhang 《Journal of polymer science. Part A, Polymer chemistry》2015,53(1):33-41
Lysine‐based polypeptides can be afforded with steerable secondary structures and tunable thermoresponsiveness through dynamic covalent OEGylation. These polypeptides were formed through dynamic imine linkage via reactions of amino moieties from poly(l ‐lysine)s with aldehydes from oligoethylene glycol (OEG)‐based dendrons. In addition to solution concentrations and pH values, macromolecular effect was found to play an important role on the imine formation. OEGylated polypeptides showed characteristic thermoresponsive properties, and their phase transition temperatures were governed predominately by terminal groups and the coverage of OEG dendrons. Notably, thermally induced aggregation would enhance the imine formation even at elevated temperature. In contrast to the covalent polypeptide representatives, the dynamic covalent polypeptides conveyed different thermoresponsiveness due to imine linkages, and their phase transition temperatures could be tuned simply by varying ratios of OEG dendrons with different hydrophilicity. Furthermore, helical conformation of these polypeptides was enhanced with attachment of OEG dendrons, and could be reversibly switched through thermally induced aggregation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 33–41 相似文献
954.
Marrying mussel inspired chemistry with SET‐LRP: A novel strategy for surface functionalization of carbon nanotubes 下载免费PDF全文
Jianwen Tian Dazhuang Xu Meiying Liu Fengjie Deng Qing Wan Zhen Li Ke Wang Xiaohui He Xiaoyong Zhang Yen Wei 《Journal of polymer science. Part A, Polymer chemistry》2015,53(16):1872-1879
Surface functionalization of carbon nanotubes (CNTs) with a thermo responsive polymer was achieved via combination of mussel inspired chemistry and surface initiated single electron transfer living radical polymerization (SET‐LRP). In this procedure, CNTs were first coated with polydopamine (PDA) through self polymerization under a rather mild condition. And then PDA functionalized CNTs bearing with amino and hydroxyl groups were further reacted with bromo isobutyryl bromide. Finally, a thermo responsive polymer poly(N‐isopropylacrylamide) (PNIPAM) was introduced on the CNTs via SET‐LRP. The successful surface modification of CNT‐PDA‐PNIPAM was evidenced by a series of characterization techniques. The resulting CNT‐PDA‐PNIPAM showed significant enhancement of dispersibility in both aqueous and organic solvents. More importantly, these CNT‐polymer nanocomposites showed obvious thermo responsive behavior due to the surface coating CNTs with PNIPAM. As compared with previous methods, this method is not required oxidation of CNTs to introduce funcitonal groups for immobilization of the polymerization initiators. More importantly, this method could also be utilized for fabricating many other polymer nanocomposites because of the strong and universal adhesive of PDA to various materials. It is therefore, the novel strategy via marrying mussel inspired chemistry with SET‐LRP should be a simple, general and effective method for surface functionalization. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1872–1879 相似文献
955.
Reduction‐cleavable hyperbranched polymers with limited intramolecular cyclization via click chemistry 下载免费PDF全文
Heng Chen Jiqiong Jia Xiao Duan Zhen Yang Jie Kong 《Journal of polymer science. Part A, Polymer chemistry》2015,53(20):2374-2380
In this contribution, we present new reduction‐cleavable hyperbranched disulfide bonds‐containing poly(ester triazole)s with limited intramolecular cyclization, which can be synthesized by the Cu(I)‐catalyzed azide–alkyne cycloaddition (CuAAC) of A2 monomer of dipropargyl 3,3′‐dithiobispropionate and B3 monomer of tris(hydroxymethyl)ethane tri(4‐azidobutanoate). The hyperbranched poly(ester triazole)s possess numerous terminal groups and weight‐average molecular weight up to 20,400 g mol?1 with a polydispersity index in the range 1.57–2.17. The CuAAC introduces rigid triazole units into the backbones of hyperbranched poly(ester triazole)s and reduces intramolecular cyclization, which is proved by topological analysis and 1H NMR spectroscopy. The disulfide bonds on backbones endow the reduction‐cleavable feature to the hyperbranched poly(ester triazole)s at the presence of dithiothreitol. It gives a novel and convenient methodology for the synthesis of reduction‐responsive functional polymer with controlled topologies, and the reduction‐cleavable hyperbranched poly(ester triazole)s with limited intramolecular cyclization are expected to possess potential in the application of stimuli‐responsive anticancer drug nanocarriers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2374–2380 相似文献
956.
Synthesis,Characterization, and thermoresponsive properties of Helical Polypeptides Derivatized from Poly(γ−4‐(3‐chloropropoxycarbonyl)benzyl‐L‐glutamate) 下载免费PDF全文
Yong Deng Xi Wang Qiulin Yuan Mengxiang Zhu Ying Ling Haoyu Tang 《Journal of polymer science. Part A, Polymer chemistry》2015,53(21):2469-2480
A series of side‐chain‐functionalized α‐helical polypeptides, i.e., poly(γ‐4‐(3‐chloropropoxycarbonyl)benzyl‐L‐glutamate) (6) have been prepared from n‐butylamine initiated ring‐opening polymerization (ROP) of γ‐4‐(3‐chloropropoxycarbonyl)benzyl‐L‐glutamic acid‐based N‐carboxyanhydride. Polypeptides bearing oligo‐ethylene‐glycol (OEG) groups or 1‐butylimidazolium salts were prepared from 6 via copper‐mediated [2+3] alkyne‐azide 1,3‐dipolar cycloaddition or nuleophilic substitution, respectively. CD and FTIR analysis revealed that the polymers adopt α‐helical conformations both in solution and the solid state. Polymers bearing OEG (m = 3) side‐chains showed reversible LCST‐type phase transition behaviors in water while polymers bearing 1‐butylimidazolium and I? counter‐anions exhibited reversible UCST‐type transitions in water. Variable‐temperature UV‐vis analysis revealed that the phase transition temperatures (Tpts) were dependent on the main‐chain length and polymeric concentration. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2469–2480 相似文献
957.
Simona Todaro Clelia Dispenza Maria Antonietta Sabatino Maria Grazia Ortore Rosa Passantino Pier Luigi San Biagio Donatella Bulone 《Journal of Polymer Science.Polymer Physics》2015,53(24):1727-1735
Xyloglucan is a natural polysaccharide having a cellulose‐like backbone and hydroxyl groups‐rich side‐chains. In its native form the polymer is water‐soluble and forms gel only in presence of selected co‐solutes. When a given fraction of galactosyl residues are removed by enzymatic reaction, the polymer acquires the ability to form a gel in aqueous solution at physiological temperatures, a property of great interest for biomedical/pharmaceutical applications. This work presents data on the effect of a temperature increase on degalactosylated xyloglucan dispersed in water at concentration low enough not to run into macroscopic gelation. Results obtained over a wide interval of length scales show that, on increasing temperature, individual polymer chains and pre‐existing clusters self‐assemble into larger structures. The process implies a structural rearrangement over a few nanometers scale and an increase of dynamics homogeneity. The relation of these findings to coil‐globule transition and phase separation is discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1727–1735 相似文献
958.
为减少荧光指示剂被水萃取流失,提高荧光膜的使用寿命,将5-氨基-邻菲咯啉与二(4,7-二苯基-邻菲咯啉)二氯化钌(Ⅱ)络合,合成带氨基的荧光指示剂[Ru(dpp)2(phen-NH2)]Cl2,并经氨基键合到有机玻璃表面。以核磁、质谱、红外验证合成荧光指示剂的结构,研究键合条件对染色有机玻璃荧光发射的影响,监测荧光强度随水浸泡时间的变化。合成荧光指示剂的荧光发射峰值波长为570 nm,键合到有机玻璃后发射光谱红移20 nm,荧光强度受溶解氧影响,响应时间约为10 s,氧猝灭比达4。染色有机玻璃的荧光稳定性好,在50 ℃水中浸泡7个月,荧光强度下降小于1%。 相似文献
959.
In this paper the strong electrochemiluminescence (ECL) nanoparticles have been prepared based on the anionic polyelectrolyte sodium polyacrylate (PAA)-ECL enhancement for Ru(bpy)32+, which were loaded by the carrier of SiO2 nanoparticle. There were two kinds of Ru(bpy)32+ for the as-prepared nanoparticles, the doped one and the exchanged one. The former was loaded inside the ECL nanoparticles by doping, in a form of ion-pair macromolecules PAA–Ru(bpy)32+. The corresponding ECL was enhanced about 2 times owing to the doping increase of Ru(bpy)32+. The latter was loaded on the PAA-doped Nafion membrane by ion exchange. The corresponding ECL was enhanced about 3 times owing to the ion-exchanging increase of Ru(bpy)32+. At the same time, ECL intensity of the doped-inside Ru(bpy)32+ was further enhanced 13 times because polyelectrolyte PAA in the doped membrane could obviously enhance electron transfer between the doped Ru(bpy)32+ and the working electrode. Furthermore, based on hydrophobic regions of the doped membrane antibody labeling could be easily realized by the as-prepared nanoparticles and then a high sensitive ECL immunoassay for HBsAg was developed. The linear range was between 1.0 and 100 pg mL−1 (R2 = 0.9912). The detection limit could be as low as 0.11 pg mL−1 (signal-to-noise ratio = 3). 相似文献
960.
Near‐infrared light (NIR) possesses great advantages for light‐responsive controllable drug release, such as deep tissue penetration and low damage to healthy tissues. Herein, a NIR‐responsive drug delivery system is developed based on a NIR dye, indocyanine green (ICG), and anticancer drug, doxorubicin (DOX)‐loaded thermoresponsive block copolymer micelles, in which the drug release can be controlled via NIR irradiation. First, block copolymers, poly(oligo(ethylene glycol) methacrylate)‐block‐poly(furfuryl methacrylate) (POEGMA‐b‐PFMA), are synthesized by sequential reversible addition‐fragmentation chain‐transfer (RAFT) polymerization, followed by modification with N‐octyl maleimide through Diels–Alder (DA) reaction to produce POEGMA‐b‐POMFMA. The self‐assembly of POEGMA‐b‐POMFMA by nanoprecipitation in aqueous solution affords the polymeric micelles which are used to simultaneously encapsulate ICG and DOX. Upon irradiation by NIR light (805 nm), the loaded DOX is released rapidly from the micelles due to partial retro DA reaction and local temperature increase‐induced faster drug diffusion by the photothermal effect. Cytotoxicity evaluation and intracellular distribution observation demonstrate significant synergistic effects of NIR‐triggered drug release, photothermal, and chemotherapy toward cancer cells under NIR irradiation.