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981.
Xiaoting Zhai Haojie Yu Li Wang Zheng Deng Zain‐ul Abdin Rongbai Tong Xianpeng Yang Yongsheng Chen Muhammad Saleem 《应用有机金属化学》2016,30(2):62-72
Aromatic azobenzene derivatives are outstanding organic photochromic compounds that possess unique photochemical properties. These compounds are widely used in research and development for various applications, especially in information storage, owing to their ability to isomerize between cis (Z) and trans (E) forms under the influence of light of different wavelengths. On account of these advantages, many efforts have been made to generalize the use of azobenzene derivatives. Furthermore, ferrocene‐based polymers and derivatives are promising candidates for functional materials due to their unique redox properties. By interlinking ferrocene with azobenzene, novel functional materials can be obtained that will integrate the excellent properties of both and will provide new applications in various fields including information storage, ion recognition, molecular devices, etc. This article provides an overview of the synthesis, properties and applications of novel ferrocene‐based polymers and derivatives containing azobenzene units. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
982.
Herein, we report the preparation of thermo‐responsive polymers in a green medium. The white, dry, fine powders were obtained directly from the cross‐linking polymerization of N‐isopropylacrylamide (NIPA) in supercritical carbon dioxide (scCO2) at pressures ranging from 10 to 28 MPa utilizing ethylene glycol dimethacrylate (EGDMA) as a cross‐linker. The effects of reaction pressure, cross‐linker ratio, initiator concentration, and reaction time were investigated. In the presence of this cross‐linker (26.4% w/w), much smaller poly(N‐isopropylacrylamide) (PNIPA) microgels (<0.2 µm diameter) were formed, and it was shown that the particle size and the morphology of the polymer were strongly dependent on the cross‐linker ratio in scCO2. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
983.
Vanda Pereira José S. Câmara Juan Cacho José C. Marques 《Journal of separation science》2010,33(9):1204-1215
This article proposes a simple and sensitive HPLC method with photo‐diode array detection for the analysis of organic acids, monomeric polyphenols and furanic compounds in wine samples by direct injection. The chromatographic separation of 8 organic acids, 2 furans and 22 phenolic compounds was carried out with a buffered solution (pH 2.70) and acetonitrile as mobile phases and a difunctionally bonded C18 stationary phase, Atlantis dC18 (250×4.6 mm, 5 μm) column. The elution was performed in 12 min for the organic acids and in 60 min for the phenolic compounds, including phenolic acids, stilbenes and flavonoids. Target compounds were detected at 210 nm (organic acids, flavan‐3‐ols and benzoic acids), 254 nm (ellagic acid), 280 nm (furans and cinnamic acid), 315 nm (hydroxycinnamic acids and trans‐resveratrol) and 360 nm (flavonoids). The RSD for the repeatability test (n=5) of peak area and retention times were below 3.1 and 0.3%, respectively, for phenolics and below 1.0 and 0.2% for organic acids. The RSDs expressing the reproducibility of the method were higher than for the repeatability results but all below 9.0%. Method accuracy was evaluated by the recovery results, with averaged values between 80 and 104% for polyphenols and 97–105% for organic acids. The calibration curves, obtained by triplicate injection of standard solutions, showed good linearity with regression coefficients higher than 0.9982 for polyphenols and 0.9997 for organic acids. The LOD was in the range of 0.07–0.49 mg/L for polyphenols (cinnamic and gallic acids, respectively) and 0.001–0.046 g/L for organic acids (oxalic and lactic acids, respectively). The method was successfully used to measure and assess the polyphenolic fingerprint and organic acids profile of red, white, rosé and fortified wines. 相似文献
984.
A facile route to design pH-responsive viscoelastic wormlike micelles: Smart use of hydrotropes 总被引:1,自引:0,他引:1
Yiyang Lin Xue Han Jianbin Huang Honglan Fu Cailan Yu 《Journal of colloid and interface science》2009,330(2):449-455
A simple and effective route to design pH-responsive viscoelastic wormlike micelles based on commercial compounds is reported. According to this route, pH-sensitive viscoelastic fluids can be easily obtained by introducing a pH-responsive hydrotrope into a surfactant solution. In this paper, the mixed system of cetyltrimethylammonium bromide (CTAB) and potassium phthalic acid (PPA) was studied in detail. This pH-sensitive fluid can be switched between a gellike state and a waterlike state within a narrow pH change. Rheology and DLS results revealed that the pH-sensitive flowing behavior was attributed to the microstructure transition between wormlike micelles and short cylindrical micelles. Combined with fluorescence anisotropy, NMR, and UV–vis, it was demonstrated that the pH response of viscoelastic fluid originated from the different binding abilities of hydrotrope to surfactant as pH varies. Furthermore, different kinds of hydrotropes can be utilized to prepare pH-responsive viscoelastic fluids in the desired pH areas. 相似文献
985.
986.
Beng H. Tan Chakravarthy S. Gudipati Hazrat Hussain Chaobin He Ye Liu Thomas P. Davis 《Macromolecular rapid communications》2009,30(12):1002-1008
We report the synthesis of a novel pH‐responsive amphiphilic block copolymer poly(dimethylaminoethyl methacrylate)‐block‐poly(pentafluorostyrene) (PDMAEMA‐b‐PPFS) using RAFT‐mediated living radical polymerization. Copolymer micelle formation, in aqueous solution, was investigated using fluorescence spectroscopy, static and dynamic light scattering (SLS and DLS), and transmission electron microscopy (TEM). DLS and SLS measurements revealed that the diblock copolymers form spherical micelles with large aggregation numbers, Nagg ≈ 30 where the dense PPFS core is surrounded by dangling PDMAEMA chains as the micelle corona. The hydrodynamic radii, Rh of these micelles is large, at pH 2–5 as the protonated PDMAEMA segments swell the micelle corona. Above pH 5, the PDMAEMA segments are gradually deprotonated, resulting in a lower osmotic pressure and enhanced hydrophobicity within the micelle, thus decreasing the Rh. However, the radius of gyration, Rg remains independent of pH as the dense PPFS cores predominate.
987.
988.
Phillip James Dorsey Dominic Scalise Rebecca Schulman 《Angewandte Chemie (International ed. in English)》2021,60(1):338-344
Living systems can form and recover complex chemical patterns with precisely sized features in the ranges of tens or hundreds of microns. We show how designed reaction–diffusion processes can likewise produce precise patterns, termed attractor patterns, that reform their precise shape after being perturbed. We use oligonucleotide reaction networks, photolithography, and microfluidic delivery to form precisely controlled attractor patterns and study the responses of these patterns to different localized perturbations. Linear and “hill”‐shaped patterns formed and stabilized into shapes and at time scales consistent with reaction–diffusion models. When patterns were perturbed in particular locations with UV light, they reliably reformed their steady‐state profiles. Recovery also occurred after repeated perturbations. By designing the far‐from‐equilibrium dynamics of a chemical system, this study shows how it is possible to design spatial patterns of molecules that are sustained and regenerated by continually evolving towards a specific steady state configuration. 相似文献
989.
TiO2纳米管阵列光电催化氧化处理氨氮废水 总被引:1,自引:0,他引:1
用电化学阳极氧化法制备了高度有序的钛基二氧化钛纳米管阵列薄膜。用场发射扫描电镜(FE-SEM)、X射线衍射(XRD)表征样品的形貌与晶型特征。以二氧化钛纳米管阵列为光阳极,石墨为对电极,测试了不同pH值和外加偏压条件下的光电流响应和光电催化氧化降解NH4Cl水溶液(以N计,100 mg·L-1)的效率。结果表明:所制备的TiO2纳米管阵列具有锐钛矿和金红石的混晶结构,且主要晶型为锐钛矿。光电流响应的强弱与光电催化氧化效率的高低相对应,降解氨氮废水的最佳条件为pH=11,偏压为1.0 V。 相似文献
990.
含铁蛋白介导的铁转运分子机制 总被引:2,自引:0,他引:2
铁是生命体必需的微量元素,因为它是一些重要功能酶的协同因子。这些功能酶有着广泛的功能,从呼吸作用到核酸的复制。但是,当铁含量多于细胞稳态的时候,它将产生对机体有毒的羟基。生物体已经发展了自身的调控机制,包括铁的摄取,存储和输出来控制细胞内的铁处于平衡态。二价阳离子转运蛋白,铁输出蛋白和hephaestin参与小肠吸收,转铁蛋白和转铁蛋白受体参与铁的摄取和转运,铁蛋白可以存储铁,铁调控蛋白的功能是调节铁代谢。这篇文章综述着重阐述了含铁蛋白介导的铁传递机制。 相似文献