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排序方式: 共有183条查询结果,搜索用时 15 毫秒
1.
Sharma Pooja Dinkar Shail Kumar Gupta D. V. 《Neural computing & applications》2021,33(19):13123-13143
Neural Computing and Applications - This work presents an efficient hybridized approach for the classification of electrocardiogram (ECG) samples into crucial arrhythmia classes to detect heartbeat... 相似文献
2.
Cost-effective valorization of carbon dioxide into bulk and specialty chemicals using catalysis will be attractive in the foreseeable future. 1,3-Oxazolidin-2-one derivatives are one of the important classes of heterocyclic compounds which have wide applications in pharmaceutical industries due to their biological activities such as antibacterial, antimicrobial, antiseptic. Various synthetic routes are employed to prepare these compounds which include phosgenation, oxidative carbonylation, etc., which make use of polluting chemicals and homogeneous catalysts. The heterogeneous catalytic processes to synthesize these derivatives are quite limited. Thus, developing a green route which is environmental friendly is highly desirable. The current work deals with development of a heterogeneous reusable catalyst and its application to synthesize 1,3-oxazolidin-2-one derivatives using carbon dioxide as a C1 source. The fact that no use of promoter or organic co-catalyst is made in the current process makes the synthesis route more favorable. Pure La–MgO and K–La–MgO with different K loading (1, 3, 5, and 7 wt%) synthesized by combustion route were screened for carbonylation of diethanol amine. 5% K–La–MgO was found to be the best catalyst. The catalyst was well characterized in virgin form and after use by various analytical techniques like TEM, SEM, XRD, CO2 and NH3-TPD, BET surface area analysis. With 5% K–La/MgO, 72% conversion of diethanol amine was achieved with 100% selectivity of the desired product at optimum conditions, i.e., 150 °C, 5 wt% K–La/MgO catalyst loading of 0.02 g/cm3 and 2.0 MPa CO2 pressure. Reaction mechanism was proposed and kinetic model developed. The apparent activation energy was calculated as 18.76 kcal/mol. The catalyst was robust and recyclable. The process is clean and green. 相似文献
3.
Pooja Sarker Sapan Kumar Sen M.N.H. Mia M.F. Pervez A.A. Mortuza Sazzad Hossain M.F. Mortuza M.H. Ali Salahuddin Nur Humayun Kabir M.A.M. Chowdhury 《Ceramics International》2021,47(3):3626-3633
This study reports the influences of gamma irradiation (GI) in the range of 20–100 kGy on CuO thin films via thermal spray pyrolysis technique on the glass substrates. The results demonstrate significant influences of GI on the crystallographic, microstructural and optical characteristics of CuO thin films. The obtained XRD results showed that the crystallinity of the films deteriorates by gradually decreasing crystallite size (from 59.13 to 46 nm) as applied gamma doses increases. However, the basic monoclinic crystal structure remains same. The dislocation density and lattice strain increased with the rise of GI absorbed dose due to the creation of defects. The values of number of crystallites per unit surface area increased as dose increased indicating the abundance of crystallization of nano CuO thin films. A UV–Vis–NIR spectrophotometer was utilized to determine the optical properties and obtained results indicated that the optical energy band gap (OBG) energies reduced from 2.00 to 1.72 eV as the doses increased from 0 to 100 kGy. No distinctions of the monoclinic phase of virgin CuO thin film have been perceived under applied absorbed doses, notwithstanding the slight deterioration of the crystallinity and narrowing the OBG. 相似文献
4.
Aswin V. Pramod Kumar Pooja Singh Anurag Gupta S. Rayaprol Anjana Dogra 《Journal of Materials Science》2015,50(1):366-373
We report investigations on polycrystalline LaCo1?x Al x O3 (x = 0–0.9) bulk samples. The solid state synthesized samples showed a coexistence of rhombohedral and monoclinic phases in the intermediate concentrations (0.2 ≤ x ≤ 0.5) and pure rhombohedral phase otherwise. The observed effect of Al doping on dc transport has been analysed on the basis of small polaron hopping mechanism. The magnetisation results presented give evidence of weak ferromagnetism and anomalous temperature dependence of coercivity which we associate to the canting of the localised high-spin Co(III) and anti-symmetric exchange interactions at low temperatures. 相似文献
5.
A pioneer study has been conducted to synthesize novel hydrogel starting from a non-cellulosic raw material, gum dammar-a triterpenoidal system, and then converting this hydrogel into an organic–inorganic composite zirconium-based ion exchanger. Gum dammar was cross-linked with polyacrylamide zirconium (IV) iodo-oxalate [Gd-cl-poly(AAm)-Zr (IV) iodo-oxalate] by incorporating inorganic precipitates into the polymeric mixture. The polymeric mixture was synthesized using gum dammar (Gd), acrylamide (AAm), N, N′-methylene-bis-acrylamide (MBA) and potassium persulphate (KPS). The reaction conditions for synthesis of hydrogel and ion exchanger such as time (120 min), temperature (70 °C), solvent (4 mL), concentration of monomer (12.97 × 10?3 mol/L), initiator (1.48 × 10?4 mol/L), cross-linker (4.22 × 10?4 mol/L) and ratio of zirconium oxychloride (0.1 M), potassium iodate (0.1 M) and oxalic acid (0.1 M) in ratio 2:3:2 were optimized to obtain maximum ion exchange capacity (2.02 meq/g). The morphology and structure of hydrogel and ion exchanger were studied using FTIR, SEM, XRD and TGA/DTA/DTG. The SEM study was followed by energy dispersive spectroscopy for elemental analysis. The ion exchanger was quite stable in various acids and bases at low concentration but it completely dissolved in acids and bases at high concentrations. Distribution studies showed that the synthesized ion exchanger had high selectivity for Pb2+ ions. Thus, the polymeric-inorganic hybrid material showed integration of both inorganic and organic characteristics within the composite material. 相似文献
6.
Making Nonwoven Fibrous Poly(ε‐caprolactone) Constructs for Antimicrobial and Tissue Engineering Applications by Pressurized Melt Gyration 下载免费PDF全文
Zewen Xu Sunthar Mahalingam Pooja Basnett Bahijja Raimi‐Abraham Ipsita Roy Duncan Craig Mohan Edirisinghe 《大分子材料与工程》2016,301(8):922-934
A pressurized melt gyration process has been used for the first time to generate poly(ε‐caprolactone) (PCL) fibers. Gyration speed, working pressure, and melt temperature are varied and these parameters influence the fiber diameter and the temperature enabled changing the surface morphology of the fibers. Two types of nonwoven PCL fiber constructs are prepared. First, Ag‐doped PCL is studied for antibacterial activity using Gram‐negative Escherichia coli and Pseudomonas aeruginosa microorganisms. The melt temperature used to make these constructs significantly influences antibacterial activity. Neat PCL nonwoven scaffolds are also prepared and their potential for application in muscular tissue engineering is studied with myoblast cells. Results show significant cell attachment, growth, and proliferation of cells on the scaffolds.
7.
Dwivedi Pooja Siddiquee Arshad Noor Maheshwari Sachin 《Russian Journal of Non-Ferrous Metals》2021,62(2):212-225
Russian Journal of Non-Ferrous Metals - Aluminum alloys have always been the material of choice for the aircraft industry owing to their versatile attributes, such as excellent strength to weight... 相似文献
8.
Pavithra Shyamsunder Shree Pooja Sridharan Vikas Madan Pushkar Dakle Cao Zeya Deepika Kanojia Wee-Joo Chng S. Tiong Ong H. Phillip Koeffler 《International journal of molecular sciences》2022,23(3)
Multiple myeloma (MM) is a hematological disease marked by abnormal growth of B cells in bone marrow. Inherent chromosomal instability and DNA damage are major hallmarks of MM, which implicates an aberrant DNA repair mechanism. Studies have implicated a role for CDK12 in the control of expression of DNA damage response genes. In this study, we examined the effect of a small molecule inhibitor of CDK12–THZ531 on MM cells. Treatment of MM cells with THZ531 led to heightened cell death accompanied by an extensive effect on gene expression changes. In particular, we observed downregulation of genes involved in DNA repair pathways. With this insight, we extended our study to identify synthetic lethal mechanisms that could be exploited for the treatment of MM cells. Combination of THZ531 with either DNA-PK inhibitor (KU-0060648) or PARP inhibitor (Olaparib) led to synergistic cell death. In addition, combination treatment of THZ531 with Olaparib significantly reduced tumor burden in animal models. Our findings suggest that using a CDK12 inhibitor in combination with other DNA repair inhibitors may establish an effective therapeutic regimen to benefit myeloma patients. 相似文献
9.
Pooja Kaur Dr. Alice Johnson Joshua Northcote-Smith Dr. Chunxin Lu Dr. Kogularamanan Suntharalingam 《Chembiochem : a European journal of chemical biology》2020,21(24):3618-3624
Immunogenic cell death (ICD) offers a method of stimulating the immune system to attack and remove cancer cells. We report a copper(II) complex containing a Schiff base ligand and a polypyridyl ligand, 4 , capable of inducing ICD in breast cancer stem cells (CSCs). Complex 4 kills both bulk breast cancer cells and breast CSCs at sub-micromolar concentrations. Notably, 4 exhibits greater potency (one order of magnitude) towards breast CSCs than salinomycin (an established breast CSC-potent agent) and cisplatin (a clinically approved anticancer drug). Epithelial spheroid studies show that 4 is able to selectively inhibit breast CSC-enriched HMLER-shEcad spheroid formation and viability over non-tumorigenic breast MCF10 A spheroids. Mechanistic studies show that 4 operates as a Type II ICD inducer. Specifically, 4 readily enters the endoplasmic reticulum (ER) of breast CSCs, elevates intracellular reactive oxygen species (ROS) levels, induces ER stress, evokes damage-associated molecular patterns (DAMPs), and promotes breast CSC phagocytosis by macrophages. As far as we are aware, 4 is the first metal complex to induce ICD in breast CSCs and promote their engulfment by immune cells. 相似文献
10.
Abdullah Ameen Saad Hassan Wasi Khan Shahid Husain Pooja Dhiman Mahavir Singh 《International Journal of Applied Ceramic Technology》2020,17(5):2430-2438
In this work, the physical properties of nanocrystalline samples of La0.7Sr0.3Mn1−xFexO3 (0.0 ≤ x ≤ 0.20) perovskite manganites synthesized by the reverse micelle (RM) technique were explored in detail. The phase purity, crystal structure, and crystallite size of the samples were determined using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. All the samples had rhombohedral crystal structure and crystallite size increased with increase in Fe content in La0.7Sr0.3MnO3. The scanning electron micrographs (SEMs) exhibited smooth surface morphology and nonuniform shape of the particles. The optical properties studied using UV-visible absorption spectroscopy revealed a decrease in the absorbance and optical band gap with an increase in Fe content in La0.7Sr0.3MnO3 compound. The temperature-dependent resistivity measurements revealed semiconducting nature of x = 0 and 0.1 samples up to the studied temperature range, while a metal-to-insulator transition was observed at higher Fe doping. Magnetic studies revealed weak ferromagnetism in all the samples and a reduction in the maximum magnetization with an increase in Fe content. A close correlation between electrical transport and magnetic properties was observed with the doping of Fe ion in La0.7Sr0.3MnO3 at Mn site. These results advocate strong interactions associated with the double exchange mechanism among Fe3+ and Mn3+ ions. 相似文献