全文获取类型
收费全文 | 16353篇 |
免费 | 1067篇 |
国内免费 | 122篇 |
专业分类
电工技术 | 257篇 |
综合类 | 76篇 |
化学工业 | 4142篇 |
金属工艺 | 387篇 |
机械仪表 | 546篇 |
建筑科学 | 559篇 |
矿业工程 | 24篇 |
能源动力 | 1076篇 |
轻工业 | 1542篇 |
水利工程 | 203篇 |
石油天然气 | 237篇 |
武器工业 | 4篇 |
无线电 | 1673篇 |
一般工业技术 | 3079篇 |
冶金工业 | 955篇 |
原子能技术 | 120篇 |
自动化技术 | 2662篇 |
出版年
2024年 | 68篇 |
2023年 | 283篇 |
2022年 | 633篇 |
2021年 | 974篇 |
2020年 | 811篇 |
2019年 | 870篇 |
2018年 | 989篇 |
2017年 | 894篇 |
2016年 | 891篇 |
2015年 | 523篇 |
2014年 | 832篇 |
2013年 | 1527篇 |
2012年 | 1022篇 |
2011年 | 1091篇 |
2010年 | 777篇 |
2009年 | 691篇 |
2008年 | 531篇 |
2007年 | 466篇 |
2006年 | 392篇 |
2005年 | 278篇 |
2004年 | 232篇 |
2003年 | 208篇 |
2002年 | 167篇 |
2001年 | 119篇 |
2000年 | 131篇 |
1999年 | 120篇 |
1998年 | 299篇 |
1997年 | 218篇 |
1996年 | 185篇 |
1995年 | 125篇 |
1994年 | 113篇 |
1993年 | 113篇 |
1992年 | 83篇 |
1991年 | 70篇 |
1990年 | 63篇 |
1989年 | 57篇 |
1988年 | 50篇 |
1987年 | 40篇 |
1986年 | 55篇 |
1985年 | 53篇 |
1984年 | 59篇 |
1983年 | 39篇 |
1982年 | 41篇 |
1981年 | 38篇 |
1980年 | 38篇 |
1978年 | 36篇 |
1977年 | 35篇 |
1976年 | 55篇 |
1975年 | 28篇 |
1974年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
981.
Using short‐term resource scheduling for assessing effectiveness of CCS within electricity generation subsector
下载免费PDF全文
![点击此处可从《American Institute of Chemical Engineers》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Colin Alie Ali Elkamel Eric Croiset Peter L. Douglas 《American Institute of Chemical Engineers》2015,61(12):4210-4234
A new methodology for assessing the effectiveness of carbon capture and storage (CCS) that does explicitly consider the detailed operation of the target electricity system is proposed. The electricity system simulation consists of three phases, each one using a modified version of an economic dispatch problem that seeks to maximize the producers’ and consumers’ surplus while satisfying the technical constraints of the system. The economic dispatch is formulated as a dynamic mixed‐integer nonlinear programming problem and implemented in general algebraic modelling system (GAMS). The generating unit with CCS is designed and simulated using Aspen Plus®. In the first case study, the operation of the IEEE RTS ’96 (Institute of Electrical and Electronics Engineers One‐Area Reliability Test System—1996) is simulated with greenhouse gas (GHG) regulation implemented in the form of CO2 permits that generators need to acquire for every unit of CO2 that it is emitted. In the second case study, CCS is added at one of the buses and the operation of the modified IEEE RTS ’96 is again simulated with and without GHG regulation. The results suggest that the detailed operation of the target electricity system should be considered in future assessments of CCS and a general procedure for undertaking this for any GHG mitigation option is proposed. Future work will use the novel methodology for assessing the effectiveness of generating units with flexible CO2 capture. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4210–4234, 2015 相似文献
982.
983.
Rheological Properties of Wormlike Micelles Formed in Aqueous Systems of 3‐Alkoxy‐2‐hydroxypropyl Trimethyl Ammonium Bromides in the Presence of Sodium Octanoate
下载免费PDF全文
![点击此处可从《Journal of surfactants and detergents》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ali Ping Peipei Geng Xilian Wei Jie Liu Junhong Zhang Dezhi Sun Xiaodong Guo Min Yang 《Journal of surfactants and detergents》2015,18(6):1117-1126
The rheological properties of aqueous systems composed of each of the four homologous cationic surfactants (3‐alkoxy‐2‐hydroxypropyl trimethyl ammonium bromides, CnHTAB, n = 12, 14, 16 and 18) in the presence of an anionic surfactant, sodium octanoate (SO), have been studied by using steady state and frequency sweep rheological measurements. The effects of surfactant concentration, hydrophobic chain length and temperature were investigated. In C14HTAB solution, the viscosity shows shear thinning in the concentration range of CC14HTAB >320 mmol/kg. Addition of SO promotes the micellar growth and results in the generation of wormlike micelles. Zero‐shear viscosity (η0) of the binary surfactant system exhibits a maximum point in the investigated concentration range, suggesting the interaction between C14HTAB and SO molecules is strongest at the optimal ratio of C14HTAB with SO. The decrease in viscosity was attributed to be the transition from entangled wormlike micelles to branching micelles after the maximum point, cryo‐TEM images revealed the changes in the structure of the wormlike micelles. 相似文献
984.
Investigation on the morphological and mechanical properties of (polyamide 6)/(poly[styrene‐co‐acrylonitrile])/(poly[styrene‐b‐{ethylene‐co‐butylene}‐b‐styrene]) ternary blends
下载免费PDF全文
![点击此处可从《乙烯基与添加剂工艺杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this work, ternary polymer blends based on (polyamide 6)/(poly[styrene‐co‐acrylonitrile])/(poly[styrene‐b‐{ethylene‐co‐butylene}‐b‐styrene]) (SEBS) triblock copolymer and a varying concentration of the reactive (maleic anhydride)‐grafted SEBS were prepared by using a melt‐blending process. The effects of the material parameters (composition of ternary blends and SEBS/[{maleic anhydride}‐grafted SEBS] concentration ratio) and blending sequence on the morphological and mechanical properties of ternary blends were studied. Taguchi experimental design methodology was employed to design the experiments and select the material and processing parameters for the optimized mechanical properties. Tensile properties (Young's modulus and yield stress) and impact strength were considered as the response variables. It was demonstrated that there is a meaningful relationship between the composition of blends, processing parameters, observed phase structure, and obtained mechanical properties. The mechanical tests showed that the highest impact strength was achieved as the dispersion of the rubbery phase achieved an optimum size of about 1 μm. J. VINYL ADDIT. TECHNOL., 23:329–337, 2017. © 2015 Society of Plastics Engineers 相似文献
985.
Synthesis of Sulfur‐Based Biocompatible Nonionic Surfactants and Their Nano‐Vesicle Drug Delivery
下载免费PDF全文
![点击此处可从《Journal of surfactants and detergents》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Imdad Ali Muhammad Raza Shah Muhammad Imran Shafiullah 《Journal of surfactants and detergents》2017,20(6):1367-1375
Nonionic surfactants are capable of forming nano‐range vesicles upon self‐assembling in an aqueous medium. These vesicles are highly stable, low in toxicity, and cost‐effective. Owing to their ability to solubilize both hydrophilic and hydrophobic substances, they are of great interest for drug solubilization and delivery. This study describes the synthesis and characterization of two new nonionic surfactants and their screening for biocompatibility and drug loading potentials in nano‐scale niosomal vesicles. They were characterized through mass spectroscopy, 1HNMR, and FT‐IR. Their critical micelle concentration (CMC) was investigated using UV–vis spectrophotometry. The biocompatibility study was carried out through blood hemolysis and in vitro cytotoxicity assays. The surfactants have very low CMC values, are highly hemo‐compatible, and were nontoxic when tested against a cell culture. They were able to form nano‐range niosomal vesicles with large variation in their size. Both new surfactants were able to encapsulate increased amounts of the drug, in this case clarithromycin. The chemical nature of the drug remained intact in the niosomal vesicles. The results suggest that these nonionic surfactants could be promising drug delivery vehicles. 相似文献
986.
Computer colour matching of paints is based on the determination of the Kubelka—Munk absorption (K) and scattering coefficients (S) of pigments. K and S are sensitive to particle size in the range of sizes employed in paint technology. The K—M theory does not provide any guidelines for the correction of the values of K and S with a change in particle size. On the other hand the Mie theory linear scattering coefficient can be calculated from a knowledge of size and refractive index of the pigment. A number of relations correlating the K—M scattering coefficient and the linear scattering coefficient have been proposed in the literature. Attempts are made to estimate the K—M scattering coefficient using a relation suggested by Mudgett and Richards and to make a comparison with experimental values. The Mie theory equations being complex, simplified equations applicable to pigment sizes for the calculation of Mie theory parameters are proposed. The viability of the simplified equations has been established by comparing the results with those obtained using the full Mie equations.The K—M scattering coefficient for titanium dioxide pigments has been determined from reflectance measurements. The particle size of titanium dioxide has been determined by a light scattering method. The K—M scattering coefficient calculated from the linear scattering coefficient obtained using the simplified expressions agrees with experimental results. This suggests a method for the correction of the values of K and S with changes in pigment particle size. 相似文献
987.
An emulsion of pioglitazone hydrochloride (drug) was prepared by mixing drug:polymer (gelatin) in different ratios of 1:0.5, 1:1, and 1:1.5 (wt/wt), respectively. These emulsions were used for the preparation of tablets of different composition. Tablet hardness increased with a decrease in concentration of polymer, while the percentage friability increased with an increase in polymer concentration in the tablet. The encapsulated tablet showed better sustained release than conventional tablets. The effect of concentration of polymer on dissolution rates of these tablets was studied using the Hixson-Crowell cube root law equation. The data obtained prove that the formulations are useful for a sustained release of pioglitazone hydrochloride, since the percentage released after 24 h was nearly 76%. The release of pioglitazone hydrochloride was influenced by the presence of polymer and different compositions of lactose. The tablet containing an emulsion of ratio 1:0.5 showed an excellent result of rate constant, better than conventional and other compositions. 相似文献
988.
ABSTRACT
A green and efficient dispersive liquid-liquid microextraction method based on a new deep eutectic solvent has been developed for the preconcentration and extraction of cobalt and nickel ions. The deep eutectic solvent is formed by mixing choline chloride (hydrogen bond acceptor) and 4-aminophenol (hydrogen bond donor). Then, it is used as a chelating agent as well as extraction solvent. Under the optimum experimental conditions, the linear ranges for Ni(II) and Co(II) were 0.80–50 and 0.50–50 µgL?1, respectively, by flame atomic absorption spectrometry. The obtained detection limits were 0.30 and 0.22 µg L?1 for Ni(II) and Co(II), respectively. 相似文献
989.
Amjad Ali Sartaj Ali Long Yu Hongsheng Liu Saud Khalid Azhar Hussain Mir Muhmmad Nasir Qayum Chen Ying 《应用聚合物科学杂志》2019,136(38):47978
Starch-based biodegradable films were prepared by using solution-casting method and reinforced by agricultural residues [apricot and walnut shell (APS and WNS) powder]. The powder of both shells was added in different ratios (0, 2.5, 5, 7.5, and 10%) to investigate the microstructures and performances (mechanical and thermal properties) of the starch-based film. Different techniques such as impact, tensile testing, scanning electron microscope, optical microscope (OM), X-ray diffraction (XRD), water vapor transmission rate (WVTR), and dynamic mechanical analysis were applied to study the thermomechanical and barrier properties of the composite films. Results showed that the incorporation of both shells significantly improved the WVTR and mechanical properties of starch-based films. The shells powder was significantly increased the Young's modulus and tensile strength of the starch-based films. Both OM and SEM results showed reasonably good compatibility between starch and reinforced shells. OM and XRD indicated that the APS and WNS not only retained their crystalline structure in the film but they also strengthened the peak intensity of the film. This phenomenon can be used to explain the mechanism of mechanical reinforcement. Since all the components used in the preparation of the films are food grade ingredients, it is expected that the films developed in this work will be used for food packaging applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47978. 相似文献
990.
The electric generating capacity of Turkey must be tripled by 2010 to meet Turkey’s electric power consumption, if the annual 8% growth in electric power consumption continues. Turkey has to make use of its renewable energy resources, such as wind and solar, not only to meet the increasing energy demand, but also for environmental reasons. Studies show that Iskenderun (36°35′N; 36°10′E) located on the Mediterranean coast of Turkey is amongst the possible wind energy generation regions. In the present study, the wind energy potential of the region is statistically analyzed based on 1-year measured hourly time-series wind speed data. The probability density distributions are derived from time-series data and distributional parameters are identified. Two probability density functions are fitted to the measured probability distributions on a monthly basis. The wind energy potential of the location is studied based on the Weibull and the Rayleigh models. 相似文献