全文获取类型
收费全文 | 2049篇 |
免费 | 107篇 |
国内免费 | 28篇 |
专业分类
电工技术 | 29篇 |
综合类 | 14篇 |
化学工业 | 447篇 |
金属工艺 | 37篇 |
机械仪表 | 76篇 |
建筑科学 | 87篇 |
矿业工程 | 4篇 |
能源动力 | 129篇 |
轻工业 | 193篇 |
水利工程 | 50篇 |
石油天然气 | 32篇 |
武器工业 | 2篇 |
无线电 | 224篇 |
一般工业技术 | 449篇 |
冶金工业 | 103篇 |
原子能技术 | 11篇 |
自动化技术 | 297篇 |
出版年
2024年 | 5篇 |
2023年 | 46篇 |
2022年 | 86篇 |
2021年 | 138篇 |
2020年 | 97篇 |
2019年 | 124篇 |
2018年 | 139篇 |
2017年 | 106篇 |
2016年 | 126篇 |
2015年 | 72篇 |
2014年 | 100篇 |
2013年 | 175篇 |
2012年 | 116篇 |
2011年 | 158篇 |
2010年 | 97篇 |
2009年 | 92篇 |
2008年 | 91篇 |
2007年 | 68篇 |
2006年 | 50篇 |
2005年 | 33篇 |
2004年 | 24篇 |
2003年 | 23篇 |
2002年 | 16篇 |
2001年 | 19篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 18篇 |
1997年 | 15篇 |
1996年 | 13篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有2184条查询结果,搜索用时 15 毫秒
91.
Synthesis of Architectural-Cubic Porous Silicon by Electroless Stain Etching in V2O5 and HF Solution
Silicon - Porous silicon (PSi) samples were prepared via electroless stain etching of silicon substrates in HF using V2O5 as an oxidant and ethanol as a surfactant for different etching times. The... 相似文献
92.
A Modified Method for the Determination of N‐Nitrosodiethanolamine in Coconut Diethanolamide Using HPLC with Dual‐Wavelength UV–Vis Detector 下载免费PDF全文
Ramin Mostafalu Abbas Banaei Mohammad Hadi Riazi Fatemeh Ghorbani 《Journal of surfactants and detergents》2016,19(2):431-435
A simple and novel method based on high‐performance liquid chromatography with dual‐wavelength ultraviolet detection at 234 and 254 nm has been developed for the determination of underivatized N‐nitrosodiethanolamine in coconut diethanolamide. The correlation coefficient obtained shows that the method is correct. 相似文献
93.
Correct Prediction of the Vibration Behavior of a High Power Ultrasonic Transducer by FEM Simulation
Amir Abdullah Abbas Pak 《The International Journal of Advanced Manufacturing Technology》2008,39(1-2):21-28
This paper presents a study on three types of finite element analyses of high power ultrasonic transducer by using the finite element commercial software called ANSYS. The transducer geometry was treated as a 2D axi- symmetric model, 3D quart and full 3D model. For all of the simulations the modeled transducer was used in modal analysis and harmonic solutions to understand its mechanical behavior and its natural frequency. A comparison was made between each type of modeling and experimental results. This comparison allows the parameters of FEM models to be iteratively adjusted and optimized and also leads to selection of the best modeling type. The achieved FEM results exhibited a remarkably high predictive potential of ANSYS in modeling and simulation and allowed control on the design and on the vibration behavior of the high power ultrasonic transducer. 相似文献
94.
Reservoir operation rules are intended to help an operator so that water releases and storage capacities are in the best interests
of the system objectives. In multi-reservoir systems, a large number of feasible operation policies may exist. System engineering
and optimization techniques can assist in identifying the most desirable of those feasible operation policies. This paper
presents and tests a set of operation rules for a multi-reservoir system, employing a multi-swarm version of particle swarm
optimization (MSPSO) in connection with the well-known HEC-ResPRM simulation model in a parameterization–simulation–optimization
(parameterization SO) approach. To improve the performance of the standard particle swarm optimization algorithm, this paper
incorporates a new strategic mechanism called multi-swarm into the algorithm. Parameters of the rule are estimated by employing a parameterization–simulation–optimization approach,
in which a full-scale simulation model evaluates the objective function value for each trial set of parameter values proposed
with an efficient version of the particle swarm optimization algorithm. The usefulness of the MSPSO in developing reservoir
operation policies is examined by using the existing three-reservoir system of Mica, Libby, and Grand Coulee as part of the
Columbia River Basin development. Results of the rule-based reservoir operation are compared with those of HEC-ResPRM. It
is shown that the real-time operation of the three reservoir system with the proposed approach may significantly outperform
the common implicit stochastic optimization approach. 相似文献
95.
In this paper, the effect of mass diffusion in a thermoelastic nanoscale beam in context Lord and Shulman theory is studied. The analytical solution in the Laplace domain is obtained for lateral deflection, temperature, displacement, concentration, stress and chemical potential. The both ends of the nanoscale beam are simply supported. The basic equations have been written in the form of a vector-matrix differential equation in the Laplace transform domain, which is then solved by an eigenvalue approach. The results obtained are presented graphically for the effect of time and mass diffusion to display the phenomena physical meaning. 相似文献
96.
Fazal Abbas Qaisar Maqbool Mudassar Nazar Nyla Jabeen Syed Zaheer Hussain Sadaf Anwaar Nasir Mehmood Muhammad Saleem Sheikh Talib Hussain Sidra Iftikhar 《IET nanobiotechnology / IET》2017,11(8):935
To grapple with multidrug resistant bacterial infections, implementations of antibacterial nanomedicines have gained prime attention of the researchers across the globe. Nowadays, zinc oxide (ZnO) at nano‐scale has emerged as a promising antibacterial therapeutic agent. Keeping this in view, ZnO nanostructures (ZnO‐NS) have been synthesised through reduction by P. aphylla aqueous extract without the utilisation of any acid or base. Structural examinations via scanning electron microscopy (SEM) and X‐ray diffraction have revealed pure phase morphology with highly homogenised average particle size of 18 nm. SEM findings were further supplemented by transmission electron microscopy examinations. The characteristic Zn–O peak has been observed around 363 nm using ultra‐violet–visible spectroscopy. Fourier‐transform infrared spectroscopy examination has also confirmed the formation of ZnO‐NS through detection of Zn–O bond vibration frequencies. To check the superior antibacterial activity of ZnO‐NS, the authors'' team has performed disc diffusion assay and colony forming unit testing against multidrug resistant E. coli, S. marcescens and E. cloacae. Furthermore, protein kinase inhibition assay and cytotoxicity examinations have revealed that green fabricated ZnO‐NS are non‐hazardous, economical, environmental friendly and possess tremendous potential to treat lethal infections caused by multidrug resistant pathogens.Inspec keywords: nanomedicine, zinc compounds, II‐VI semiconductors, wide band gap semiconductors, nanoparticles, scanning electron microscopy, X‐ray diffraction, antibacterial activity, transmission electron microscopy, particle size, Fourier transform infrared spectra, ultraviolet spectra, visible spectra, enzymes, biochemistry, molecular biophysics, microorganisms, drugs, toxicology, bonds (chemical), semiconductor growth, nanofabrication, vibrational modesOther keywords: green synthesised zinc oxide nanostructures, Periploca aphylla extract, antibacterial potential, multidrug resistant pathogens, multidrug resistant bacterial infections, antibacterial nanomedicines, P. aphylla aqueous extract, structural examinations, scanning electron microscopy, X‐ray diffraction, pure phase morphology, homogenised average particle size, SEM, transmission electron microscopy, Fourier‐transform infrared spectroscopy, bond vibration frequency, antibacterial activity, disc diffusion assay, colony forming unit testing, S. marcescens, E. cloacae, E. coli, ultraviolet‐visible spectroscopy, protein kinase inhibition assay, cytotoxicity, lethal infections, ZnO 相似文献
97.
Farnaz Khaleseh Abbas Hemmati Azandaryani Fatemeh Fathian Kolahkaj Mozafar Khazaei Katayoun Derakhshandeh 《IET nanobiotechnology / IET》2021,15(3):257
Epirubicin (EPI) is one of the potent breast cancer (BC) chemotherapeutic agents, but its adverse effects limit its efficacy. Herein, EPI was selected to be loaded in liposomal carrier, which has been targeted by a monoclonal antibody, Herceptin. The preparation process of liposomes was a modified ethanol injection method followed by Herceptin conjugation. The in vitro cell toxicity and cellular uptake of optimum formulation against HER2+ and HER2− cancer cell lines were evaluated. The results showed that the drug loading (DL%) and encapsulation efficiency (EE%) of liposome preparation method yielded 30.62% ± 0.49% and 62.39% ± 8.75%, respectively. The average size of naked liposomes (EPI‐Lipo) and immunoliposomes (EPI‐Lipo‐mAb) was 234 ± 9.86 and 257.26 ± 6.25 nm, with a relatively monodisperse distribution, which was confirmed by SEM micrographs. The release kinetic followed Higuchi model for both naked and immunoliposomes. In vitro cytotoxicity study on three different BC cell lines including BT‐20, MDA‐MB‐453 and MCF‐7 demonstrated higher toxicity of EPI in the Herceptin conjugated form (EPI‐Lipo‐mAb) in comparison with the free EPI and EPI‐Lipo in HER2 overexpressing cell line. In addition, the cellular uptake study showed a higher uptake of immunoliposomes by MCF‐7 cells in comparison with naked liposomes. In conclusion, these data show that the targeted delivery of EPI to breast cancer cells can be achieved by EPI‐Lipo‐mAb in vitro, and this strategy could be used for breast cancer therapy with further studies. 相似文献
98.
Diabetic retinopathy (DR) diagnosis through digital fundus images requires clinical experts to recognize the presence and importance of many intricate features. This task is very difficult for ophthalmologists and time-consuming. Therefore, many computer-aided diagnosis (CAD) systems were developed to automate this screening process of DR. In this paper, a CAD-DR system is proposed based on preprocessing and a pre-train transfer learning-based convolutional neural network (PCNN) to recognize the five stages of DR through retinal fundus images. To develop this CAD-DR system, a preprocessing step is performed in a perceptual-oriented color space to enhance the DR-related lesions and then a standard pre-train PCNN model is improved to get high classification results. The architecture of the PCNN model is based on three main phases. Firstly, the training process of the proposed PCNN is accomplished by using the expected gradient length (EGL) to decrease the image labeling efforts during the training of the CNN model. Secondly, the most informative patches and images were automatically selected using a few pieces of training labeled samples. Thirdly, the PCNN method generated useful masks for prognostication and identified regions of interest. Fourthly, the DR-related lesions involved in the classification task such as micro-aneurysms, hemorrhages, and exudates were detected and then used for recognition of DR. The PCNN model is pre-trained using a high-end graphical processor unit (GPU) on the publicly available Kaggle benchmark. The obtained results demonstrate that the CAD-DR system outperforms compared to other state-of-the-art in terms of sensitivity (SE), specificity (SP), and accuracy (ACC). On the test set of 30,000 images, the CAD-DR system achieved an average SE of 93.20%, SP of 96.10%, and ACC of 98%. This result indicates that the proposed CAD-DR system is appropriate for the screening of the severity-level of DR. 相似文献
99.
Nadia Tabassum Allah Ditta Tahir Alyas Sagheer Abbas Hani Alquhayz Natash Ali Mian Muhammad Adnan Khan 《计算机、材料和连续体(英文)》2021,67(3):3129-3141
Cloud computing is becoming popular technology due to its functional properties and variety of customer-oriented services over the Internet. The design of reliable and high-quality cloud applications requires a strong Quality of Service QoS parameter metric. In a hyperconverged cloud ecosystem environment, building high-reliability cloud applications is a challenging job. The selection of cloud services is based on the QoS parameters that play essential roles in optimizing and improving cloud rankings. The emergence of cloud computing is significantly reshaping the digital ecosystem, and the numerous services offered by cloud service providers are playing a vital role in this transformation. Hyperconverged software-based unified utilities combine storage virtualization, compute virtualization, and network virtualization. The availability of the latter has also raised the demand for QoS. Due to the diversity of services, the respective quality parameters are also in abundance and need a carefully designed mechanism to compare and identify the critical, common, and impactful parameters. It is also necessary to reconsider the market needs in terms of service requirements and the QoS provided by various CSPs. This research provides a machine learning-based mechanism to monitor the QoS in a hyperconverged environment with three core service parameters: service quality, downtime of servers, and outage of cloud services. 相似文献
100.
Sayilkan F Asiltürk M Kiraz N Burunkaya E Arpaç E Sayilkan H 《Journal of hazardous materials》2009,162(2-3):1309-1316
Pure anatase, nanosized and Sn(4+) ion doped titanium dioxide (TiO(2)) particulates (TiO(2)-Sn(4+)) were synthesized by hydrothermal process. TiO(2)-Sn(4+) was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn(4+) doping to TiO(2) against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO(2)-Sn(4+) in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO(2)-Sn(4+) is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO(2)-Sn(4+) from 10 to 50% in the coating solution increased antibacterial effect. 相似文献