全文获取类型
收费全文 | 434篇 |
免费 | 21篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 98篇 |
金属工艺 | 7篇 |
机械仪表 | 9篇 |
建筑科学 | 19篇 |
能源动力 | 12篇 |
轻工业 | 66篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 34篇 |
一般工业技术 | 91篇 |
冶金工业 | 26篇 |
原子能技术 | 3篇 |
自动化技术 | 70篇 |
出版年
2023年 | 10篇 |
2022年 | 31篇 |
2021年 | 44篇 |
2020年 | 16篇 |
2019年 | 20篇 |
2018年 | 38篇 |
2017年 | 26篇 |
2016年 | 23篇 |
2015年 | 19篇 |
2014年 | 24篇 |
2013年 | 34篇 |
2012年 | 23篇 |
2011年 | 14篇 |
2010年 | 18篇 |
2009年 | 20篇 |
2008年 | 18篇 |
2007年 | 8篇 |
2006年 | 3篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有456条查询结果,搜索用时 31 毫秒
71.
Data were collected from 42 buffalo with toxic puerperal metritis in 2 large herds, with a history of dystocia, prolapse, and retained placenta. All buffalo were subjected to detailed clinical examination including external inspection, vaginoscopy, and transrectal palpation of the cervix, uterus, and ovaries. Swabs for bacteriology and biopsies for histopathology were collected from the uterine lumen from each cow. Character, odor, and estimation of polymorphonuclear cells of the vaginal mucus were scored. Blood samples were collected from cows for creatine kinase and aspartate amino-transferase measurement. The most predisposing factor causing toxic puerperal metritis was retained placenta (52.4%), and the most prevalent bacteria in uterine lumen were Escherichia coli, Arcanobacterium pyogenes, Staphylococcus aureus, and Fusobacterium necrophorum (18.5, 16.7, 13.0, and 9.3%, respectively). High levels of polymorphonuclear cells were observed in buffalo infected with A. pyogenes and gram-negative anaerobic bacteria (62.1 and 76.4%). A high prevalence of gram-negative anaerobes was isolated from uteri harboring A. pyogenes (13.0%). Buffalo with toxic puerperal metritis had significantly higher creatine kinase and aspartate aminotransferase activities than controls (499.2 ± 23.9 and 208.3 ± 11.3 vs. 242.7 ± 12.9 and 166.8 ± 11.5 U/L, respectively). In a conclusion, gram-negative anaerobes and other facultative pathogens including A. pyogenes were important pathogens that cause severe uterine inflammation. 相似文献
72.
Alaa Fahmy Karam S. El-Nasser Ibraheem O. Ali Tarek M. Salama Korinna Altmann 《Journal of Adhesion Science and Technology》2013,27(24):2641-2656
The electrospray ionization (ESI) method was used for deposition of thin films of poly(acrylic acid) (PAA) on Cu/ZSM-5 (5 wt.% Cu) and Ag–Cu/ZSM-5 (1 wt.% Ag and 4 wt.% Cu) composites. For comparative purposes, the ZSM-5 zeolite was synthesized under hydrothermal conditions and loaded with PAA under the same treating conditions as the composites. This method allowed the formation of uniform polymer films of controlled thickness on conductive substrates. The structural characteristics were characterized by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, atomic force microscopy and X-ray diffraction (XRD). The deposited PAA layer over ZSM-5 acts as a common dispersing and stabilizing agent through coordination-driven guest-templated polymer via interaction of Ag+ and Cu2+ with carboxylic acid groups, thus increasing and controlling the adhesion and the release of metallic species. A short exposure to light and temperature has reduced the metal ions to Cu0 and Ag0 metallic nanoparticles. The results of XRD analysis let suggest that the interaction of Cu and Ag with carboxylic groups of PAA inhibits the formation of large metallic silver particles. These samples were being studied for their potential as antibacterial agents toward the bacterial strains such as Staphylococcus pneumonia, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa as Gram positive and Gram negative bacteria, respectively. Aspergillus fumigatus and Candida albicans as Fungi were also evaluated. The Cu/ZSM-5 and Ag–Cu/ZSM-5 nanocomposites coated with a 10 nm thick PAA layer exhibit significant antibacterial activity. 相似文献
73.
The objectives of the study were to investigate the microwelding conditions related to diffusion mechanism and elemental migration metallurgical and microscopy investigation, and to establish the fundamental corrosion mechanism on the properties of small welding and brazing areas that consist different materials. This study focuses on the weldability of Ti /Ni using microspot brazing technology by selection of brazing condition current, 2, 2.5, 3, 3.5 and 4 kA, voltage 2 V, load 60 N and welding time 25–50 ms, this welding condition effective on brazing temperature optimization this condition. Ti and Ni were selected as base metals. Four types of metal fillers were used as filler foils, sandwiched between Ti/Ni. First type of metal fillers was, 65Ni–35Cu foil, melting point 846 °C; the second was, 71Ag–28Cu–1Mg foil, melting point 775 °C; the third was, 80Ag–18Cu–2Ti foil, melting point 782 °C; and fourthly was, 73Ni–18Cr–9Si foil, melting point 917 °C. The electrode tip face chosen was circuitous in form. All brazed joint were made by microspot brazing method. Brazing was done under normal atmospheric condition. 相似文献
74.
Two-dimensional (2-D) formulae for estimating discharge capacity of straight compound channels are reviewed and applied to
overbank flows in straight fixed and mobile bed compound channels. The predictive capabilities of these formulae were evaluated
using experimental data obtained from the small-scale University of Birmingham channel. Full details of these data and key
references may be found at the following www.flowdata.bham.ac.uk (university website). 2-D formulae generally account for
bed shear, lateral shear, and secondary flow effects via 3 coefficients f, λ and Γ In this paper, the secondary flow term (Γ) used within the 2-D methods analysed here is ignored in all applications. Two different 2-D formulae almost give practically
the same results for the same data when the secondary flow term is ignored. For overall test cases, the value of dimensionless
eddy viscosity λ used in 2-D formulae was kept at 0·13 as recommended for open channels. 2-D formulae gave good predictions for most of the
data sets studied in comparison with the traditional 1-D methods, namely the Single Channel Method (SCM) and the Divided Channel
Method (DCM). The accuracy of predictions of 2-D formulae was increased by calibrating of λ value where the calibration was needed. For overall data, the average errors for each method were Lateral Division Methods
(LDMs), with λ value of 0·13, 2·8%, DCM 14·3% and SCM −26·8%. The average error was 0·5% for LDMs with the calibrated values of λ 相似文献
75.
Enhancing Inflow Forecasting Model at Aswan High Dam Utilizing Radial Basis Neural Network and Upstream Monitoring Stations Measurements 总被引:4,自引:4,他引:0
Ahmed El-Shafie Alaa E. Abdin Aboelmagd Noureldin Mohd R. Taha 《Water Resources Management》2009,23(11):2289-2315
The Nile River is considered the main life artery for so many African countries especially Egypt. Therefore, it is of the
essence to preserve its water and utilize it very efficiently. Developing inflow-forecasting model is considered the technical
way to effectively achieve such preservation. The hydrological system of the Nile River under consideration has several dams
and barrages that are equipped with control gates. The improvement of these hydraulic structures’ criteria for operation can
be assessed if reliable forecasts of inflows to the reservoir are available. Recently, the authors developed a forecasting
model for the natural inflow at Aswan High Dam (AHD) based on Artificial Intelligence (AI). This model was developed based
on the historical inflow data of the AHD and successfully provided accurate inflow forecasts with error less than 10%. However,
having several forecasting models based on different types of data increase the level of confidences of the water resources
planners and AHD operators. In this study, two forecasting model approach based on Radial Basis Function Neural Network (RBFNN)
method for the natural inflow at AHD utilizing the stream flow data of the monitoring stations upstream the AHD is developed.
Natural inflow data collected over the last 30 years at four monitoring stations upstream AHD were used to develop the model
and examine its performance. Inclusive data analysis through examining cross-correlation sequences, water traveling time,
and physical characteristics of the stream flow data have been developed to help reach the most suitable RBFNN model architecture.
The Forecasting Error (FE) value of the error and the distribution of the error are the two statistical performance indices
used to evaluate the model accuracy. In addition, comprehensive comparison analysis is carried out to evaluate the performance
of the proposed model over those recently developed for forecasting the inflow at AHD. The results of the current study showed
that the proposed model improved the forecasting accuracy by 50% for the low inflow season, while keep the forecasting accuracy
in the same range for the high inflow season. 相似文献
76.
When choosing sites for monitoring of soil moisture for hydrological purposes, a suitable process that considers the factors influencing soil moisture level should be followed. In this study, two multi-criteria decision-making (MCDM) methods, the multi-influencing factor (MIF) method and the analytical hierarchy process (AHP) method, were used to identify the optimal soil moisture monitoring (SMM) sites in the Dry Creek Catchment in South Australia. The most representative areas for nine SMM sites were obtained using the MIF method, considering the factors of rainfall, soil type, land use, catchment slope, elevation, and upslope accumulated area (UAA). The AHP method was used to select the optimal sites using the site-specific criteria. 30.3% of the catchment area in the Australian Water Resources Assessment Landscape (AWRA-L) Grid_DC2 can be considered acceptable as representative area with the MIF method. Four potential sites were evaluated for each AWRA-L grid using the relative weights of the site-specific criteria with the AHP method. The Grid_DC2 required two sites that had the highest overall weight chosen with the AHP analysis. The procedure was repeated for the remaining four AWRA-L grids within the study area to select the required SMM sites. 相似文献
77.
Mirja Kaizer Ahmmed Fatema Ahmmed Hong Tian Alan Carne Alaa El‐Din Bekhit 《Comprehensive Reviews in Food Science and Food Safety》2020,19(1):64-123
For several decades, there has been considerable interest in marine‐derived long chain n‐3 fatty acids (n‐3 LCPUFAs) due to their outstanding health benefits. n‐3 LCPUFAs can be found in nature either in triglycerides (TAGs) or in phospholipid (PL) form. From brain health point of view, PL n‐3 is more bioavailable and potent compared to n‐3 in TAG form, as only PL n‐3 is able to cross the blood–brain barrier and can be involved in brain biochemical reactions. However, PL n‐3 has been ignored in the fish oil industry and frequently removed as an impurity during degumming processes. As a result, PL products derived from marine sources are very limited compared to TAG products. Commercially, PLs are being used in pharmaceutical industries as drug carriers, in food manufacturing as emulsifiers and in cosmetic industries as skin care agents, but most of the PLs used in these applications are produced from vegetable sources that contain less (without EPA, DPA, and DHA) or sometimes no n‐3 LCPUFAs. This review provides a comprehensive account of the properties, structures, and major sources of marine PLs, and provides focussed discussion of their relationship to brain health. Epidemiological, laboratory, and clinical studies on n‐3 LCPUFAs enriched PLs using different model systems in relation to brain and mental health that have been published over the past few years are discussed in detail. 相似文献
78.
Yueying Yao Wenmeng He Xifan Cai Alaa El-Din Ahmed Bekhit Baojun Xu 《International Journal of Food Science & Technology》2022,57(8):4868-4878
This study investigated the physicochemical and sensory properties of six types of plant-based milk alternatives prepared from soybean, peanut, adlay, adzuki bean, oat and buckwheat at a 1:9 grain-to-water ratio. The results revealed that all plant-based milk types had stable hydrocolloid systems, except for the buckwheat milk alternative that had undergone a gelatinisation process that affected its rheological and sensory properties. The pH values and total solid content of the prepared plant-based milk samples ranged between 6.60 to 6.83 and 2.13 to 8.17 g/100 mL, respectively. The sensory results showed that the overall liking score of adlay, adzuki bean and peanut milk alternative was 5.32, 5.30 and 6.10, respectively, suggesting a potential for commercial production. In conclusion, this investigation provides new insights on several new plant sources for plant-based milk alternatives. Further studies are required to investigate the digestibility and the nutritional effects expected from plant-based milk alternatives such as protein bioavailability, and the effects on human health compared to other animal milks. 相似文献
79.
80.