全文获取类型
收费全文 | 750篇 |
免费 | 44篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 218篇 |
金属工艺 | 16篇 |
机械仪表 | 17篇 |
建筑科学 | 13篇 |
能源动力 | 25篇 |
轻工业 | 91篇 |
水利工程 | 5篇 |
石油天然气 | 7篇 |
无线电 | 90篇 |
一般工业技术 | 125篇 |
冶金工业 | 59篇 |
原子能技术 | 9篇 |
自动化技术 | 108篇 |
出版年
2024年 | 4篇 |
2023年 | 15篇 |
2022年 | 42篇 |
2021年 | 44篇 |
2020年 | 42篇 |
2019年 | 39篇 |
2018年 | 34篇 |
2017年 | 32篇 |
2016年 | 29篇 |
2015年 | 35篇 |
2014年 | 41篇 |
2013年 | 54篇 |
2012年 | 53篇 |
2011年 | 42篇 |
2010年 | 26篇 |
2009年 | 22篇 |
2008年 | 26篇 |
2007年 | 25篇 |
2006年 | 15篇 |
2005年 | 15篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有797条查询结果,搜索用时 15 毫秒
71.
In present communication, we propose a modified resource allocation strategy, namely, hybrid connection algorithm, for achieving efficient restoration in WDM optical networks. The main theme of the algorithm is that, while attempting connection establishment, a wavelength is reserved in advance for providing resources for backup lightpaths. The analysis and the comparison of the proposed strategy with other existing strategies has been undertaken using metrics such as, restoration efficiency, number of wavelength links used by primary and backup lightpaths, and the percent link utilization. The proposed strategy provides 100% restoration efficiency and much better performance than the existing techniques. 相似文献
72.
Crop Reference Evapotranspiration: A Discussion of the Concept,Analysis of the Process and Validation 总被引:2,自引:0,他引:2
The study at first recalls the concept of “potential evapotranspiration” (PET), originally considered equal to the evaporation
climatic demand; then, it reminds the steps of its progressive evolution toward the concept of “reference crop evapotranspiration”
(ET0) determined on irrigated grass. A physical analysis conducted on the evaporation process is subsequently reported to help
clarifying the links between ET0 and evaporation climatic demand. This analysis clearly demonstrates that the equivalence of ET0 to evaporation climatic demand is not correct, although still common assumption in recent scientific literature, particularly
in hydrology. The study also identifies two processes acting in opposite directions in the dynamics of ET0: (1) the climatic variables determining the evaporation demand, and (2) the canopy resistance which slows down the response
of irrigated grass to such demand. The analysis of the respective impact of these two processes on ET0 dynamics shows that the available energy is the dominant process. This variable takes into account the 60–70% of the variation
of ET0, both at hourly and daily scales, while canopy resistance only explains 10–20% of ET0 variation of irrigated grass. The study regards different climatic situations. Possible effects on practical applications
were also discussed in the conclusions, together with comments on the correct canopy resistance modelling. 相似文献
73.
Nikhil Verma Harpreet Singh Divya Khanna Prashant Singh Rana Sanjay Kumar Bhadada 《IET systems biology》2019,13(5):243
In humans, oxidative stress is involved in the development of diabetes, cancer, hypertension, Alzheimers’ disease, and heart failure. One of the mechanisms in the cellular defence against oxidative stress is the activation of the Nrf2‐antioxidant response element (ARE) signalling pathway. Computation of activity, efficacy, and potency score of ARE signalling pathway and to propose a multi‐level prediction scheme for the same is the main aim of the study as it contributes in a big amount to the improvement of oxidative stress in humans. Applying the process of knowledge discovery from data, required knowledge is gathered and then machine learning techniques are applied to propose a multi‐level scheme. The validation of the proposed scheme is done using the K‐fold cross‐validation method and an accuracy of 90% is achieved for prediction of activity score for ARE molecules which determine their power to refine oxidative stress.Inspec keywords: cancer, cellular biophysics, biochemistry, drugs, molecular biophysics, proteins, learning (artificial intelligence), medical computingOther keywords: oxidative stress, Nrf2‐antioxidant response element signalling pathway, ARE signalling pathway, diabetes, cancer, hypertension, Alzheimers’ disease, heart failure, machine learning techniques, K‐fold cross‐validation method, ARE molecules 相似文献
74.
75.
Prabhat Sarkar Soumitra Rana Debashis Jana Subham Mandal Chhanda Mukhopadhyay 《Advanced Synthesis \u0026amp; Catalysis》2024,366(7):1661-1668
A tert-butyl nitrite (TBN) promoted visible-light-induced one-pot C−N cross coupling reaction of 3-alkylidene-2-oxindoles with benzene-1,2-diamine was explored. Simultaneously, the indoline motif of 3-alkylidene-2-oxindoles as well as 3-ylidene oxindoles are regioselectively nitrated at the C-6 position by in-situ formed NO2 radical. (E)-3-(2-(aryl)-2-oxoethylidene)oxindole and (E)-3-ylidene oxindole produce distinct nitrated diastereomeric coupling products, a phenomenon influenced by the steric bulk of the functional group. The experimental findings suggest the potential involvement of a radical pathway in this reaction. 相似文献
76.
Tahreem Tanweer Nosheen Fatima Rana Iqra Saleem Iqra Shafique Sultan M. Alshahrani Hanadi A. Almukhlifi Amenah S. Alotaibi Sohad Abdulkaleg Alshareef Farid Menaa 《International journal of molecular sciences》2022,23(24)
Antibacterial restorative materials against caries-causing bacteria are highly preferred among high-risk patients, such as the elderly, and patients with metabolic diseases such as diabetes. This study aimed to enhance the antibacterial potential of resin composite with Magnesium-doped Zinc oxide (Mg-doped ZnO) nanoparticles (NPs) and to look for their effectiveness in the alloxan-induced diabetic model. Hexagonal Mg-doped ZnO NPs (22.3 nm diameter) were synthesized by co-precipitation method and characterized through ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. The Mg-doped ZnO NPs (1, 2.5 and 5% w/w) were then evaluated for antibacterial activity using a closed system in vitro biofilm model. Significant enhancement in the antibacterial properties was observed in composites with 1% Mg-doped ZnO compared to composites with bare ZnO reinforced NPs (Streptococcus mutans, p = 0.0005; Enterococcus faecalis, p = 0.0074, Saliva microcosm, p < 0.0001; Diabetic Saliva microcosm, p < 0.0001). At 1–2.5% Mg-doped ZnO NPs concentration, compressive strength and biocompatibility of composites were not affected. The pH buffering effect was also achieved at these concentrations, hence not allowing optimal conditions for the anaerobic bacteria to grow. Furthermore, composites with Mg-doped ZnO prevented secondary caries formation in the secondary caries model of alloxan-induced diabetes. Therefore, Mg-doped ZnO NPs are highly recommended as an antibacterial agent for resin composites to avoid biofilm and subsequent secondary caries formation in high-risk patients. 相似文献
77.
78.
79.
M Kunitani S Wolfe S Rana C Apicella V Levi G Dollinger 《Canadian Metallurgical Quarterly》1997,16(4):573-586
This paper describes the development and validation of a new off-line approach to quantitate both covalent and noncovalent, in-solution aggregates present in protein formulations and compares the new assay to established HPLC methods. This off-line analysis is well suited for use in QC release testing, formulation development and stability indicating applications. An inexpensive, continuous source HPLC fluorometer has been adapted with the addition of second order filters for use as a sensitive right-angle scatterometer which can determine the molecular weight of protein aggregates in solution. When used as an HPLC detector, right-angle light scattering is a sensitive method which can determine the molecular weight of peaks separable by HPLC, thus discriminating between monomers of different conformations and aggregates. The weight-averaged molecular weight of aggregate peaks can be calculated with system calibration, yielding the average number of monomers per aggregate. If the protein concentration is high enough for an adequate signal, the off-line technique of right-angle light scattering of protein formulations has advantages of convenience and speed over the HPLC approach. Samples are placed in standard fluorometer cuvettes and toluene is used as a calibrator. Data are presented which show the off-line (static) method to be extremely rapid, rugged and precise. The accuracy of this approach is demonstrated through cross-validation to traditional GPC analysis of protein aggregate distributions. This non-invasive light scattering approach is particularly useful when non-covalent protein aggregation is reversible and readily altered by chromatographic separations typically used for characterizing aggregates. 相似文献
80.
A novel approach to synthesize a new generation of composite nanoparticles consisting of a photocatalytic shell of anatase-titania
and a magnetic core of nickel ferrite has been adopted combining reverse micelle and chemical hydrolysis techniques. Titania
is an effective anti-microbial agent that can be directly sprayed on infected areas of the human body or environment. Unfortunately,
titania is an electrical insulator and is difficult to extract from the sprayed surface after treatment. The titania photocatalytic
shell provides good antimicrobial capability that renders the bacteria inactive and removes the organic pollutants, while
the nickel ferrite magnetic core enables controlled delivery of composite nanoparticles through the application of a small
magnetic field, encouraging their application as removable anti-microbial photocatalyst nanoparticles.
For more information, contact R.D.K. Misra, University of Louisiana at Lafayette, Center for Structural and Functional Materials,
P.O. Box 44130, Lafayette, LA 70504-4130; (337) 482-6430; e-mail dmisra@louisiana.edu. 相似文献