全文获取类型
收费全文 | 18106篇 |
免费 | 2073篇 |
国内免费 | 2699篇 |
专业分类
化学 | 14767篇 |
晶体学 | 182篇 |
力学 | 844篇 |
综合类 | 277篇 |
数学 | 2180篇 |
物理学 | 4628篇 |
出版年
2024年 | 53篇 |
2023年 | 190篇 |
2022年 | 525篇 |
2021年 | 650篇 |
2020年 | 650篇 |
2019年 | 593篇 |
2018年 | 515篇 |
2017年 | 811篇 |
2016年 | 919篇 |
2015年 | 760篇 |
2014年 | 1010篇 |
2013年 | 1634篇 |
2012年 | 1313篇 |
2011年 | 1111篇 |
2010年 | 966篇 |
2009年 | 1043篇 |
2008年 | 1036篇 |
2007年 | 1078篇 |
2006年 | 967篇 |
2005年 | 861篇 |
2004年 | 797篇 |
2003年 | 666篇 |
2002年 | 595篇 |
2001年 | 517篇 |
2000年 | 524篇 |
1999年 | 475篇 |
1998年 | 429篇 |
1997年 | 372篇 |
1996年 | 348篇 |
1995年 | 275篇 |
1994年 | 282篇 |
1993年 | 252篇 |
1992年 | 154篇 |
1991年 | 95篇 |
1990年 | 85篇 |
1989年 | 53篇 |
1988年 | 51篇 |
1987年 | 27篇 |
1986年 | 39篇 |
1985年 | 40篇 |
1984年 | 33篇 |
1983年 | 13篇 |
1982年 | 30篇 |
1981年 | 18篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1977年 | 5篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1959年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Shi‐Zhou Fu Bao‐Lin Yin De‐zhi Sun 《Journal of Dispersion Science and Technology》2013,34(7):1112-1116
The foam performances of 3‐dodecoxy‐2‐hydroxypropyl trimethylammonium chloride (C12TAC) have been determined in the existence of different relative amount of polymer. The experimental results show that the foaming ability of the mixture systems of the C12TAC/PEG and C12TAC/PVP is stronger than that of the surfactant solutions in the absence of polymer, and with the increase of relative amount of polymer both foaming efficiency and foam stability of the surfactant solutions are evidently enhanced. For the aqueous solution of the surfactant, effect of temperature on foaming properties has also been examined. The results show that both the foaming ability and stability of the foams of the surfactant solutions are highest (or strongest) at 30°C. 相似文献
962.
The organic/inorganic hybrid nanomaterials containing silica nanoparticles are synthesized by sol-gel crosslinking process. The tetraethoxysilane (TEOS) and γ-aminopropyltriethoxylsilane as coupling agents are used as a precursor. The 2,4,6-tri [(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) as crosslinking agent is used to form covalent bonds among the inorganic nanoparticles. The chemical and morphological structures of the organic/inorganic hybrid are characterized with FTIR spectra, 29Si-NMR, x-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and atomic force microscope (AFM). The results show that the organic/inorganic hybrid forms covalent bond between the inorganic nanoparticle and Tri-EBAC. The network organic/inorganic hybrid can form good film with even nanometer particles. The network organic/inorganic hybrids nanomaterial not only exhibits the thermal properties of inorganic compounds, but also exhibits the thermal properties of organic polymer. 相似文献
963.
T.L.-G. Carlson K. Larsson Y. Miezis 《Journal of Dispersion Science and Technology》2013,34(2):197-208
In connection with studies of technical functionality of lipids in cereals, the aqueous systems of lipids from rye and tri-ticale flour are described and compared to different wheat culti-vars. Rye lipids give a lamellar liquid-crystalline phase with very small ordered regions, and this phase is continuously changed into an L2-phase with increasing water content. Triticale lipids exhibit phase equilibria in between lipids of wheat and of rye. Evidence is given for a significant role of the lamellar liquid--crystalline phase with regard to technical functionality when the cereal flour is worked in water to give a dough. 相似文献
964.
Maryam Zohri Alireza Nomani Tarane Gazori Ismaeil Haririan Seyed Saeed Mirdamadi Seyed Kazem Sadjadi 《Journal of Dispersion Science and Technology》2013,34(4):576-582
The aim of this study was to evaluate the effect of the polymeric ratios on the characteristics of chitosan/alginate (ch/alg) self-assembled nanoparticles and their potential as protein delivery vehicle. The nanoparticles were prepared using proper mixing of polymers in presence or absence of bovine serum albumin (BSA) as a protein model. Three formulations of nanoparticles comprising ch/alg ratios of 2:1, 1:1, and 1:2 were prepared. Size, shape and zeta potential of the formulations were studied by scanning electron microscopy (SEM) and nanosizer instruments. FTIR, and differential scanning calorimetery (DSC) studies were performed to investigate polymer-polymer or polymer-protein interactions. Release profiles and entrapment efficiencies of the nanoparticles were determined by calorimetric technique using appropriate techniques. Entrapment efficiency was 70% for ch/alg ratio of 1:1, 65% for 1:2, and 60% for 2:1. The z-average size of the nanoparticles were 403, 205, and 318 nm for ch/alg ratios of 2:1, 1:1, and 1:2, respectively. Average zeta potentials were ?47, +15, ?25 mV for 2:1, 1:1, and 1:2 as well. Considering the favorable features required for protein delivery systems, ch/alg (1:1) due to its smallest size, highest loading, and most homogenous shape was regarded as the best ratio. 相似文献
965.
Yongbing Pei Yuling Jiang Hong Huang Huanqin Chen 《Journal of Dispersion Science and Technology》2013,34(9):1279-1284
The acrylate redispersible polymer powder (RPP) was produced from acrylate latex via spray drying, which was synthesized by latex polymerization with the configuration of soft core and hard shell. The powder's redispersibility and stability of its reconstituted latex were achieved through incorporating monomer methacrylic acid (MAA), which has functional carboxyl group and can provide an ionization effect in alkaline range. The influence of pH value and MAA amount on the redispersibility and stability were studied. The stabilization mechanism for reconstituted latex was also investigated. The acrylate RPP has good redispersibility at MAA of 4–5% and pH values between 9.0 and 10.0. The reconstituted latex is stable at these conditions due to high zeta potential and strong electrostatic repulsion force. 相似文献
966.
Adsorption of Ethoxylated Nonyl Phenol (ENP) surfactant from its aqueous solution onto a commercial tire cutting from different sites. Outer Peristalitic (O.P.), Outer Smouth (O.S.), and Internal Tire (I.T.) is studied after different immersion times, 24, 48, 72, and 144 hrs at 30° C. The adsorption isotherms are determined by a surface tension method. A two stepped L-type isotherm is characteristic below the CMC of ENP; above this concentration the isotherm deviates from the L-type and the slope of the isotherm increases sharply. A Langmuir fit has been found below the CMC of ENP. From the maximum amounts adsorbed at pseudo-plateau (Tmax of the tested samples it was found that the efficiency of adsorption onto the rubber surface decreases in the order, O.P. > O.S. > I.T. 相似文献
967.
Qianping Ran Ponisseril Somasundaran Changwen Miao Jiaping Liu Shishan Wu Jian Shen 《Journal of Dispersion Science and Technology》2013,34(6):790-798
Comb polymers are commonly used as dispersants to stabilize highly concentrated cement suspensions. The effectiveness of such polymeric additives to stabilize these suspensions is determined to a large extent by the amount adsorbed. In this study we investigated the adsorption characteristics of various comb dispersant containing different graft densities on surfaces of cement particle. The effect of inorganic salts on their adsorption was also examined in order to elucidate their adsorption mechanism. The results show that the adsorption of comb polymer dispersants on cement surface conforms approximately to Langmuir's adsorption isotherm and the characteristic plateau A s and adsorption free energy ΔGads are largely dependent on the anionic group content of the comb polymers. The A s and ΔGads increase with increasing anionic group content. This information suggests that the adsorption of comb polymers on cement surfaces is dominated by electrostatic interaction between COO-groups on the comb polymers and the positive surface of the cement. This conclusion is supported by effects of inorganics such as calcium and sulfate ions, and diffuse reflectance FTIR spectroscopy. The implication of results for tuning polymers for the required performance in cement manufacture should be noted. 相似文献
968.
Huixian Wei Jianguo Ma Zhengwu Wang 《Journal of Dispersion Science and Technology》2013,34(3):319-326
Formulation optimization of emulsifiers for preparing multiple emulsions was performed in respect of stability by using artificial neural network (ANN) technique. Stability of multiple emulsions was expressed by the percentage of reserved emulsion volume of freshly prepared sample after centrifugation. Individual properties of multiple emulsions such as droplet size, δ, viscosity of the primary and the multiple emulsions were also considered. A back‐propagation (BP) network was well trained with experimental data pairs and then used as an interpolating function to estimate the stability of emulsions of different formulations. It is found that using mixtures of Span 80 and Tween 80 with different mass ratio as both lipophilic and hydrophilic emulsifiers, multiple W/O/W emulsions can be prepared and the stability is sensitive to the mixed HLB numbers and concentration of the emulsifiers. By feeding ANN with 39 pairs of experimental data, the ANN is well trained and can predict the influences of several formulation variables to the immediate emulsions stability. The validation examination indicated that the immediate stability of the emulsions predicted by the ANN is in good agreement with measured values. ANN therefore could be a powerful tool for rapid screening emulsifier formulation. However, the long‐term stability of the emulsions is not good, possibly due to the variation of the HLB number of the mixed monolayers by diffusion of emulsifier molecules, but can be greatly improved by using a polymer surfactant Arlacel P135 to replace the lipophilic emulsifier. 相似文献
969.
Current-voltage electrical behavior of in situ microfibrillar carbon black (CB)/poly(ethylene terephthalate) (PET)/polyethylene (PE) (m-CB/PET/PE) composites with various CB concentrations at ambient temperatures was studied under a direct-current electric field. The current-voltage (I-V) curves exhibited nonlinearity beyond a critical value of voltage. The dynamic random resistor network (DRRN) model was adopted to semi-qualitatively explain the nonlinear conduction behavior of m-CB/PET/PE composites. Macroscopic nonlinearity originated from the interfacial interactions between CB/PET micro fibrils and additional conduction channels. Combined with the special conductive networks, an illustration was proposed to interpret the nonlinear I-V characteristics by a field emission or tunneling mechanism between CB particles in the CB/PET microfibers intersections. 相似文献
970.
Synthesis and ion transport properties of hot-pressed solid polymer electrolytes (SPEs), (1-x) PEO: x KI, where x is the content of KI in wt%, are reported. A hot-press technique has been used for the formation of the polymeric membranes in place of the usual solution cast method. The composition (80PEO:20KI) was identified as the highest conducting polymer electrolyte on the basis of compositional dependent conductivity studies of PEO:KI films. A conductivity enhancement of more than two orders of magnitude from that of the pure PEO was achieved. Materials characterization and ion transport mechanism were explained by using various experimental techniques. 相似文献