全文获取类型
收费全文 | 780篇 |
免费 | 87篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 4篇 |
综合类 | 2篇 |
化学工业 | 329篇 |
金属工艺 | 17篇 |
机械仪表 | 13篇 |
建筑科学 | 12篇 |
矿业工程 | 1篇 |
能源动力 | 38篇 |
轻工业 | 103篇 |
水利工程 | 14篇 |
石油天然气 | 6篇 |
无线电 | 62篇 |
一般工业技术 | 155篇 |
冶金工业 | 10篇 |
原子能技术 | 10篇 |
自动化技术 | 93篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 49篇 |
2021年 | 72篇 |
2020年 | 62篇 |
2019年 | 68篇 |
2018年 | 91篇 |
2017年 | 70篇 |
2016年 | 71篇 |
2015年 | 37篇 |
2014年 | 56篇 |
2013年 | 78篇 |
2012年 | 51篇 |
2011年 | 48篇 |
2010年 | 36篇 |
2009年 | 15篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有869条查询结果,搜索用时 448 毫秒
851.
Magnetohydrodynamic (MHD) equilibrium is vulnerable to numerous destabilizing mechanisms. Instabilities introduce distortions
to the plasma magnetic surfaces and its boundaries, their driving force being the radial gradient of plasma toroidal current
density. For certain modal numbers, internal kink modes may develop, and their study is feasible according to the energy principle,
in which the change in total potential energy due to the disturbance is evaluated. In this article, we present a totally new
analysis of MHD equilibrium and stability, and apply it to Damavand tokamak which has a large aspect ratio. For this purpose,
we combine perturbation and Green’s function methods to solve for the equilibrium configuration. At this stage, plasma profiles
are found explicitly in terms of Bessel functions, and we present a simple expression for estimation of total toroidal plasma
current. Then the rest of plasma profiles, including poloidal magnetic flux, safety factor, and toroidal current density,
are obtained and plotted. In the next step, we turn to the stability calculations and show that Damavand plasma is resistant
to most of the disturbances. 相似文献
852.
Tianhe Huang Guan Wang Mohammad-Ali Shahbazi Yuancheng Bai Jingrui Zhang Guobing Feng Elham Asadian Fatemeh Ghorbani-Bidkorpeh Zhiyuang Yang Yuanai Li Qingqing Huo Yingxin Liu Dongfei Liu 《Advanced functional materials》2023,33(2):2210627
A versatile surface decoration strategy to efficiently encapsulate water-soluble peptides is developed. By assembling peptide molecules into nanoparticles, diverse physiochemical properties of these compacted molecules are equalized to the surface properties of nanoparticles. Primarily driven by the generic electrostatic attractions, the surface of as-prepared peptide nanoparticles is decorated with charged amino acids-grafted poly(lactic-co-glycolic acid). This adsorbed polymer layer versatilely blocks the phase transfer of peptide nanoparticles by increasing their affinity to the dispersed phase solvent molecules. Attributed to the ultrahigh encapsulation efficiencies (> 96%), the peptide mass fraction inside the obtained microcomposites is higher than 48%. The plasma calcium level has been efficiently reduced for ≈3 weeks with only one single injection of salmon calcitonin-encapsulated microcomposite in osteoporotic rats. Similarly, one single injection of exenatide-encapsulated microcomposites efficiently controls the glycemic level in type 2 diabetic rats for up to 3 weeks. Overall, the developed versatile surface decoration strategy efficiently encapsulates peptides and improves their pharmacokinetic features, regardless of the molecular structure of peptide cargos. 相似文献
853.
Spent desulphurization catalysts are considered a major secondary source of valuable metals. The contents of nickel and vanadium present in these catalysts, accompanied by environmental rules, have attracted scientists to explore diverse options for their effective processing. The electrometallurgy recovery of Ni and V from the spent desulphurization Ni-Mo-V/Al2O3 catalyst is described in this study. Using flat plate graphite electrodes, the electrochemical deposition of Ni and V from spent catalyst in an acid solution (HNO3/H2SO4) was investigated. By the central composite design of the response surface methodology, the effect of the operating factors was examined and optimized. At the ideal conditions of reaction temperatures of 84.0 and 42.0°C, electrolysis times of 5.6 and 4.4 h, liquid/solid ratios of 22.7 and 15.4 ml/g, and current densities of 229.0 and 255.6 A/m2, respectively, the recovery efficiencies of Ni and V were 81.96% and 93.07%. The statistical analysis revealed that the expected data (R2 = 0.9984 and R2 = 0.9883) were in good agreement with the observed data (R2 = 0.9984), with an average variation from experimental data of 0.78% and 0.65% for the optimum conditions of Ni and V recovery, respectively. It shows that the Ni and V nanoparticles deposited have a spherical form with purities of 84.39% and 90.76%, respectively. Because of its great efficiency and purity, the current study can provide a dependable procedure for extracting Ni and V from solid waste. 相似文献
854.
Fasihi Shirehjini Oktay Babapour Mofrad Farshid Shahmohammadi Mohammadreza Karami Fatemeh 《Magma (New York, N.Y.)》2023,36(1):43-53
Magnetic Resonance Materials in Physics, Biology and Medicine - Despite the critical role of Magnetic Resonance Imaging (MRI) in the diagnosis of brain tumours, there are still many pitfalls in the... 相似文献
855.
Mohammad Ahmadi Dr. Yaghoub Ahmadyousefi Zahra Salimi Dr. Rasoul Mirzaei Dr. Rezvan Najafi Dr. Bagher Amirheidari Dr. Fatemeh Rahbarizadeh Javad Kheshti Armin Safari Dr. Meysam Soleimani 《ChemMedChem》2023,18(3):e202200506
Active targeting using biological ligands has emerged as a novel strategy for the targeted delivery of diagnostic agents to tumor cells. Conjugating functional targeting moieties with diagnostic probes can increase their accumulation in tumor cells and tissues, enhancing signal detection and, thus, the sensitivity of diagnosis. Due to their small size, ease of chemical synthesis and site-specific modification, high tissue penetration, low immunogenicity, rapid blood clearance, low cost, and biosafety, peptides offer several advantages over antibodies and proteins in diagnostic applications. Epidermal growth factor receptor (EGFR) is one of the most promising cancer biomarkers for actively targeting diagnostic and therapeutic agents to tumor cells due to its active involvement and overexpression in various cancers. Several peptides for EGFR-targeting have been identified in the last decades, which have been obtained by multiple means including derivation from natural proteins, phage display screening, positional scanning synthetic combinatorial library, and in silico screening. Many studies have used these peptides as a targeting moiety for diagnosing different cancers in vitro, in vivo, and in clinical trials. This review summarizes the progress of EGFR-targeting peptide-based assays in the molecular diagnosis of cancer. 相似文献
856.
Mehdi Tarkhani Seyyed Abbas Mousavi Mahdieh Asadollahi Dariush Bastani Fatemeh Pourasad 《Polymer Engineering and Science》2023,63(3):986-1000
This study aims to investigate polysulfone (PSF) mixed matrix membranes (MMMs) properties containing zirconium-based and titanium-based metal–organic frameworks (MOFs). for hemodialysis application. The nanoparticles were synthesized, and the membranes were produced by the phase inversion method. Membrane characterization conducted by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), field emission Scanning electron microscope (FE-SEM), energy-dispersive x-ray analysis (EDX), transmission electron microscopy (TEM), x-ray diffraction (XRD), and atomic force microscopy (AFM) confirmed the presence of MOF nanoparticles. Also, the evaluation of the specific surface area of nanoparticles was done by BET. The water contact angle reduced from 64.4° to 51.2°, indicating the hydrophilicity improvement, enhancing the pure water flux from 46.8 L/m2h for the pristine membrane to 76.7 L/m2h for the pristine membrane M4. The total fouling resistance decreased from 30% to 21%, and the bovine serum albumin (BSA) adsorption of modified membranes was lower than that of the pristine membrane. Urea and creatinine were cleared significantly for modified ones, up to 82.6% and 72.1%, respectively, and all membranes showed BSA retention of more than 93%. A comparison between MMMs that contained UIO-66-NH2 and MIL-125-NH2 showed that the former had a better effect on the performance. M4 had better results, indicating high water flux, the lowest fouling resistance, high porosity, lower BSA adsorption, proper clearance for urea and creatinine, and 94.2% BSA retention. 相似文献
857.
Cellulose nanocrystals (CNCs) are biodegradable nanoparticles with a high aspect ratio and abundant surface hydroxyl groups resulting in negatively charged hydrophilic surfaces that make them an ideal candidate to be incorporated in thin-film nanocomposite (TFN) membranes. In this study, we modified the CNCs via acetylation (ACNCs) to reduce their hydrophilicity and via reaction with L-cysteine (CysCNCs) to impart them with functionality that promoted their interaction with the trimesoyl chloride organic monomer used in the preparation of the poly(amide) layer of the TFN membranes. These modifications allowed us to question in which monomer solution the nanoparticles should be dispersed. Addition of the unmodified CNCs in either the aqueous or organic monomer solution showed little difference in membrane performance. However, the addition of either the ACNCs or the CysCNCs to the organic monomer solution led to a significant increase in membrane performance in reverse osmosis (RO) and nanofiltration (NF) systems compared to their addition to the aqueous monomer solution. In addition, the CysCNCs exhibited performance very near the upper-bound line for RO and NF. 相似文献
858.
Javan-Bari Hamid Rafiee Reza Bahadori Fatemeh 《Clean Technologies and Environmental Policy》2023,25(8):2777-2788
Clean Technologies and Environmental Policy - Steelwork is one of the main CO2 emitters due to three main off-gases of blast furnace gas, coke oven gas, and basic oxygen furnace... 相似文献
859.
Silicon - The core/shell CaO@SiO2-SO3H nanoparticles were prepared by stabilizing of sulfonic acid on the surface of silica-coated CaO nanoparticles. The structure of CaO@SiO2-SO3H was... 相似文献
860.
Food Science and Biotechnology - Mulberry is prone to microbial contamination due to mechanical damage during the harvesting. This study aimed to determine, and optimize fruit microbial loads, and... 相似文献