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排序方式: 共有192条查询结果,搜索用时 12 毫秒
41.
Jie Jiang Chongyi Ling Tao Xu Wenhui Wang Xianghong Niu Amina Zafar Zhenzhong Yan Xiaomu Wang Yumeng You Litao Sun Junpeng Lu Jinlan Wang Zhenhua Ni 《Advanced materials (Deerfield Beach, Fla.)》2018,30(40)
Defect‐induced trap states are essential in determining the performance of semiconductor photodetectors. The de‐trap time of carriers from a deep trap can be prolonged by several orders of magnitude as compared to shallow traps, resulting in additional decay/response time of the device. Here, it is demonstrated that the trap states in 2D ReS2 can be efficiently modulated by defect engineering through molecule decoration. The deep traps that greatly prolong the response time can be mostly filled by protoporphyrin molecules. At the same time, carrier recombination and shallow traps in‐turn play dominant roles in determining the decay time of the device, which can be several orders of magnitude faster than the as‐prepared device. Moreover, the specific detectivity of the device is enhanced (as high as ≈1.89 × 1013 Jones) due to the significant reduction of the dark current through charge transfer between ReS2 and molecules. Defect engineering of trap states therefore provides a solution to achieve photodetectors with both high responsivity and fast response. 相似文献
42.
Ugarov MV Egan T Khabashesku DV Schultz JA Peng H Khabashesku VN Furutani H Prather KS Wang HW Jackson SN Woods AS 《Analytical chemistry》2004,76(22):6734-6742
When used in small molar ratios of matrix to analyte, derivatized fullerenes and single wall nanotubes are shown to be efficient matrices for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The mixing of an acidic functionalized fullerene with a solution of bioanalyte, depositing a dried droplet, and irradiating with a pulsed nitrogen laser yields protonated or cationized molecular ions. Derivatized fullerenes could offer several advantages over conventional MALDI matrices: a high analyte ionization efficiency, a small molar ratios (less than 1) of matrix/analyte, and a broader optical absorption spectrum, which should obviate specific wavelength lasers for MALDI acquisitions. The major disadvantage to the use of fullerenes is the isobaric interference between matrix and analyte ions; however, it is overcome by using MALDI-ion mobility time-of-flight (IM-oTOF) mass spectrometry to preseparate carbon cluster ions from bioanalyte ions prior to TOF mass analysis. However, an alternative to the dried droplet preparation of fullerene MALDI samples is the aerosolization of matrix-analyte solutions (or slurries) followed by impacting the aerosol onto a stainless surface. We also demonstrate that the fullerene matrices can be used to acquire spectra from rat brain tissue. 相似文献
43.
Amina Zafar Haiyan Nan Zainab Zafar Zhangting Wu Jie Jiang Yumeng You Zhenhua Ni 《Nano Research》2017,10(5):1608-1617
Optical emission efficiency of two-dimensional layered transition metal dichalcogenides (TMDs) is one of the most important parameters affecting their optoelectronic performance.The optimization of the growth parameters by chemical vapor deposition (CVD) to achieve optoelectronic-grade quality TMDs is,therefore,highly desirable.Here,we present a systematic photoluminescence (PL) spectroscopic approach to assess the intrinsic optical and crystalline quality of CVD grown MoS2 (CVD MoS2).We propose the use of the intensity ratio between the PL measured in air and vacuum as an effective way to monitor the intrinsic optical quality of CVD MoS2.Low-temperature PL measurements are also used to evaluate the structural defects in MoS2,via defect-associated bound exciton emission,which well correlates with the field-effect carrier mobility of MoS2 grown at different temperatures.This work therefore provides a sensitive,noninvasive method to characterize the optical properties of TMDs,allowing the tuning of the growth parameters for the development of optoelectronic devices. 相似文献
44.
Yosra Braham Houcine Barhoumi Abderrazak Maaref Amina Bakhrouf Nicole Jaffrezic-Renault 《Materials science & engineering. C, Materials for biological applications》2013,33(8):4504-4511
The development of enzymatic sensors for biological purposes such as biomedicine, pharmacy, food industry, and environmental toxicity requires the purification step of the enzyme. To prevent the loss of the enzyme activity, a new strategy is held in order to immobilize the bacteria. It will constitute the biological sensing element leading to a high operational stability and multiple adaptations to various conditions such as temperature, pH and ionic strength changes. In this work we describe the development of a urea biosensor by immobilizing Proteus mirabilis bacteria onto an insulator–semiconductor electrode on functionalized Fe3O4 nanoparticles (NPs), using cationic, Poly (allylamine hydrochloride) then anionic, Poly (sodium 4-styrenesulfonate) polyelectrolytes, BSA (serum bovin albumin), and glutaraldehyde as a cross-linking agent. The response of P. mirabilis to urea addition is evaluated in homogeneous and heterogeneous phases. Before the immobilization step, the activity of urease produced from the P. mirabilis bacteria was attempted using the ion ammonium selective electrodes (ISEs). Adhesion of the bacteria cells on IS electrodes have been studied using contact angle measurements.After immobilization of the bacteria, on the (Si/SiO2/Si3N4) and (Si/SiO2) substrates, the relationship between the evolution of the flat band potential ?VFB and the urea concentration is found to be linear for values ranging from 10? 2 M to 10? 5 M. 相似文献
45.
Lamghari Amina Dimitrakopoulos Roussos Senécal Renaud 《Optimization and Engineering》2022,23(2):1139-1164
Optimization and Engineering - Mineral value chains, also known as mining complexes, involve mining, processing, stockpiling, waste management and transportation activities. Their optimization is... 相似文献
46.
47.
Amina A Attia Badie S Girgis Soheir A Khedr 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(6):611-619
Two activated carbons were obtained from pistachio shells by impregnation with H3PO4 under standard conditions of acid concentration (50 wt%) and heat treatment at 773 K for 2 h. The soaking time was 24 and 72 h for the two samples before thermal pyrolysis. Analysis of the N2/77 K adsorption isotherms proved that both were highly adsorbing carbons with considerable microporosity, and that the prolonged contact with activant enhanced total porosity (surface area and pore volume) and increased the amount of mesoporosity. Adsorption isotherms of probe molecules, viz methylene blue (MB), rhodamine B (RB), phenol (P) and p‐nitrophenol (PNP), were determined at room temperature, from aqueous solutions. Both the Langmuir and Freundlich model adsorption equations show satisfactory fit to experimental data. Both carbons exhibit similar adsorption parameters irrespective of their porosity characteristics. The sequence of uptake per unit weight was: PNP > MB > RB > P. Low affinity towards phenol may be associated with its competition with water molecules which are more favourably attracted to the acid surface which has a high oxygen functionality. Preferred adsorption in the order PNP > MB > RB is proposed to be a function of carbon porosity, related to the increased molecular dimensions of the solutes. Adsorption from a binary mixture of equal concentrations of MB and RB showed reduced uptake for both sorbates in comparison to the single component experiments. RB removal surpasses that of MB in the binary test and may be attributed to lower water solubility and higher molecular dimensions. Copyright © 2003 Society of Chemical Industry 相似文献
48.
Poole Debra A.; Lindsay D. Stephen; Memon Amina; Bull Ray 《Canadian Metallurgical Quarterly》1995,63(3):426
Psychotherapists were surveyed regarding clients' memories of childhood sexual abuse (CSA). The 3 samples were highly similar on the vast majority of measures. Respondents listed a wide variety of behavioral symptoms as potential indicators of CSA, and 71% indicated that they had used various techniques (e.g., hypnosis, interpretation of dreams) to help clients recover suspected memories of CSA . Across samples, 25% of the respondents reported a constellation of beliefs and practices suggestive of a focus on memory recovery, and these psychologists reported relatively high rates of memory recovery in their clients. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
49.
Adel Tellili Nouceyba Abdelkrim Amina Challouf Mohamed-Naceur Abdelkrim 《国际自动化与计算杂志》2018,15(6):736-746
This paper studies the fault tolerant control, adaptive approach, for linear time-invariant two-time-scale and three-time-scale singularly perturbed systems in presence of actuator faults and external disturbances. First, the full order system will be controlled using ε-dependent control law. The corresponding Lyapunov equation is ill-conditioned due to the presence of slow and fast phenomena. Secondly, a time-scale decomposition of the Lyapunov equation is carried out using singular perturbation method to avoid the numerical stiffness. A composite control law based on local controllers of the slow and fast subsystems is also used to make the control law ε-independent. The designed fault tolerant control guarantees the robust stability of the global closed-loop singularly perturbed system despite loss of effectiveness of actuators. The stability is proved based on the Lyapunov stability theory in the case where the singular perturbation parameter is sufficiently small. A numerical example is provided to illustrate the proposed method. 相似文献
50.
Amina Souag Raúl Mazo Camille Salinesi Isabelle Comyn-Wattiau 《Requirements Engineering》2016,21(2):251-283
Security is a concern that must be taken into consideration starting from the early stages of system development. Over the last two decades, researchers and engineers have developed a considerable number of methods for security requirements engineering. Some of them rely on the (re)use of security knowledge. Despite some existing surveys about security requirements engineering, there is not yet any reference for researchers and practitioners that presents in a systematic way the existing proposals, techniques, and tools related to security knowledge reuse in security requirements engineering. The aim of this paper is to fill this gap by looking into drawing a picture of the literature on knowledge and reuse in security requirements engineering. The questions we address are related to methods, techniques, modeling frameworks, and tools for and by reuse in security requirements engineering. We address these questions through a systematic mapping study. The mapping study was a literature review conducted with the goal of identifying, analyzing, and categorizing state-of-the-art research on our topic. This mapping study analyzes more than thirty approaches, covering 20 years of research in security requirements engineering. The contributions can be summarized as follows: (1) A framework was defined for analyzing and comparing the different proposals as well as categorizing future contributions related to knowledge reuse and security requirements engineering; (2) the different forms of knowledge representation and reuse were identified; and (3) previous surveys were updated. We conclude that most methods should introduce more reusable knowledge to manage security requirements. 相似文献