首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   302篇
  免费   5篇
  国内免费   4篇
电工技术   4篇
综合类   3篇
化学工业   14篇
金属工艺   5篇
机械仪表   17篇
建筑科学   13篇
能源动力   8篇
轻工业   131篇
水利工程   1篇
石油天然气   3篇
无线电   10篇
一般工业技术   46篇
冶金工业   4篇
原子能技术   15篇
自动化技术   37篇
  2023年   4篇
  2022年   10篇
  2021年   17篇
  2020年   7篇
  2019年   1篇
  2018年   5篇
  2017年   7篇
  2016年   12篇
  2015年   2篇
  2013年   75篇
  2012年   18篇
  2011年   25篇
  2010年   18篇
  2009年   10篇
  2008年   13篇
  2007年   9篇
  2006年   5篇
  2005年   10篇
  2004年   4篇
  2002年   2篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
  1991年   3篇
  1990年   1篇
  1989年   6篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1983年   6篇
  1981年   3篇
  1980年   4篇
  1979年   2篇
  1978年   3篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1968年   1篇
排序方式: 共有311条查询结果,搜索用时 31 毫秒
301.
The purpose of this research was to determine and compare the physicochemical properties of probiotic frozen yoghurts made from camel and cow milks. The results showed that the viscosity of frozen yoghurt made from camel milk was significantly higher (P < 0.05) than that from cow milk. Less fat was destabilised in frozen yoghurt made from camel milk. The frozen yoghurt made from camel milk required more time for melting than that from cow milk. Flavour scores of the frozen yoghurt made from camel milk constituents were significantly lower (P < 0.05) than those made from cow milk.  相似文献   
302.
Paired wild‐type cultures consisting of a Lactobacillus paracasei subsp. paracasei (three strains) or Pediococcus pentosaceus (one strain) and a Pediococcus inopinatus (five strains) were used as adjunct cultures in the production of Iranian white brined cheese. After 8 weeks of ripening, adjunct‐treated cheeses produced by L. paracasei subsp. paracasei and P. inopinatus received significantly higher scores for flavour/taste, aroma, texture and overall preference than those produced by P. pentosaceus and P. inopinatus as well as the control cheese (P < 0.05). In conclusion, a greater improvement of sensory quality of cheeses was strongly associated with the presence of L. paracasei subsp. paracasei rather than pediococci.  相似文献   
303.
The objective of this paper was to investigate seasonal variations in bulk somatic cell totals and milk composition, evaluate the influence of somatic cell count (SCC) on milk fat and protein content and determine the effects of SCC on dairy farm profitability. A total of 1440 samples were analysed. Data were obtained by randomly collecting five samples of bulk tank milk from each of 24 dairy farms every month from April 2008 to March 2009. Milk was analysed for titratable protein, fat content and SCC (direct microscopic cell count). The highest total bulk SCCs were observed during autumn and winter. Conversely, higher levels of milk fat and protein were generated during spring and summer. A significant negative correlation was noted between SCC and milk composition, daily milk yield and milk returns. By logarithmic function, a significant negative relationship was observed between SCC and milk composition or milk returns. In conclusion, this study demonstrates that the SCC is a useful tool for judging dairy farm profit and milk quality.  相似文献   
304.
The supercritical carbon dioxide (SC-CO2) process involves pressurizing CO2 in a chamber which generates liquid phase of carbon dioxide. Pressurized liquid CO2 has a strong extraction capability of organic and inorganic compounds. The recent studies have also demonstrated that antimicrobial effect of SC-CO2 due extraction some cellular components of microorganisms. The efficacy of a supercritical carbon dioxide treatment on alfalfa seeds contaminated with Escherichia coli K12 was tested at 2000, 3000, and 4000 psi at 50C. Samples were treated for 15, 30, and 60 min at each pressure. After pummeling the seed samples in 0.1% peptone water, the initial and final Escherichia coli and total aerobic bacteria on the seeds were determined by plating on 3M Petri Films. After 48 h of incubation at 37 C, the colonies were enumerated. Treated seeds were evaluated in terms of germination characteristics. For aerobic plate count, the effect of pressure in the range of 2000–4000 psi was not statistically significant (p > 0.05) even though 85.6% inactivation was achieved at 4000 psi for 60 min. For E. coli, the reductions for 2000, 3000, and 4000 psi treatments for 15 min were 26.6, 68.1, and 81.3%, respectively. As the time was increased from 15 to 60 min at 4000 psi, the percent E. coli reduction increased from 81.3% to 92.8%. The percent germination for all treatments was over 90%. There was no significant difference (p > 0.05) in the germination rate of treated and untreated seeds. Supercritical carbon dioxide treatments demonstrated a reduction of E. coli K12 and total aerobic counts without affecting the germination characteristics of alfalfa seeds (p < 0.05). This study was a step in the direction of improving safety of alfalfa seeds used to produce fresh sprouts, which have been the cause of several outbreaks.  相似文献   
305.
This paper introduces a novel solar-assisted heat pump system with phase change energy storage and describes the methodology used to analyze the performance of the proposed system. A mathematical model was established for the key parts of the system including solar evaporator, condenser, phase change energy storage tank, and compressor. In parallel to the modelling work, an experimental set-up of the proposed solar energy storage heat pump system was developed. The experimental data showed that the designed system is capable of meeting cold day heating demands in rural areas of Yanbian city located in Jilin province of China. In day-time operation, the solar heat pump system stores excess energy in the energy storage tank for heating purposes. A desired indoor temperature was achieved; the average coefficient of performance of solar heat pump was identified as 4.5, and the system showed a stable performance throughout the day. In night-time operation, the energy stored in the storage tank was released through a liquid-solid change of phase in the employed phase-change material. In this way, the provision of continuous heat for ten hours was ensured within the building, and the desired indoor air conditions were achieved.  相似文献   
306.
为研究电弧重熔对390A合金显微组织、力学性能和摩擦学性能的影响,对采用常规感应熔炼法制备的390A合金锭进行电弧重熔.采用光学显微镜和扫描电镜观察合金的显微组织,采用布氏硬度法和拉伸试验测试合金的力学性能,采用球对盘式摩擦磨损试验机对摩擦学性能进行研究.结果表明,感应熔炼和电弧重熔的390A合金中均含有α(Al)、A...  相似文献   
307.
用铁尾矿陶粒替代普通混凝土天然粗骨料,根据《轻骨料混凝土技术规程》(JGJ/T 12—2019)设计配合比,制备LC30~LC40的铁尾矿陶粒混凝土.测定和计算其力学性能、耐久性、经济性,并与普通混凝土作对比.结果表明,铁尾矿陶粒混凝土能够满足《轻骨料混凝土技术规程》(JGJ/T 12—2019)中LC30配制强度,其...  相似文献   
308.
The association of gut microflora and human health is being increasingly recognized, and the impact of gut microflora on the host is well characterized, including the body’s energy metabolism and immune system maintenance. Several human diseases, including metabolic, autoimmune, obesity, hypothyroidism, and intestinal disorders, are closely associated with gut dysbiosis. Inorganic nanoparticles (NPs) are extensively utilized in numerous fields due to their distinctive, attractive physicochemical properties. Estimation of the potential impacts of NPs, with a high number of microorganisms inside the human body (microbiota) and its genomes (microbiome), represents one of the most important aspects of nano-toxicology. This review article aims to provide information on the association of gut microflora alterations to diseases and describe the impacts of various inorganic NPs, including silver, zinc, selenium, titania, silicon, and copper, on gut microflora. Research on the effect of inorganic NPs on gut microflora of animal models and the poultry industry is reviewed. The response of pathogenic Enterobacter species to inorganic NPs has been expounded in detail. This review also highlights the need to focus on the ancillary effects of various inorganic NPs on gut microflora to expedite the suitable advancement of these particles for future use. Finally, the key opportunistic areas for the application of nanotechnology are underlined to manipulate the microbiome of gut dysbiosis, provide an overview, and address potential challenges and our perspective on this evolving field.  相似文献   
309.
Salinity is one of the major abiotic factors that limit the growth and productivity of plants. Foliar application of plant growth regulators (PGRs) may help plants ameliorate the negative impacts of salinity. Thus, a field experiment was conducted at the Botanical Garden University of Balochistan, Quetta, to explore the potential role of PGRs, i.e., moringa leaf extract (MLE; 10%), proline (PRO; 1 µM), salicylic acid (SA; 250 µM), and thiourea (TU; 10 mM) in ameliorating the impacts of salinity (120 mM) on Plantago ovata, an important medicinal plant. Salinity hampered plant photosynthetic pigments and metabolites but elevated oxidative parameters. However, foliar application of PGRs enhanced photosynthetic pigments, including Chl b (21.11%), carotenoids (57.87%) except Chl a, activated the defense mechanisms by restoring and enhancing the metabolites, i.e., soluble sugars (49.68%), soluble phenolics (33.34%), and proline (31.47%), significantly under salinity stress. Furthermore, foliar supplementation of PGRs under salt stress led to a decrease of about 43.02% and 43.27% in hydrogen peroxide and malondialdehyde content, respectively. Thus, PGRs can be recommended for improved photosynthetic efficiency and metabolite content that can help to get better yield under salt stress, with the best and most effective treatments being those of PRO and MLE to predominately ameliorate the harsh impacts of salinity.  相似文献   
310.
The objective of the current study is to propose an expert system framework based on a supervised machine learning technique (MLT) to predict the seismic performance of low- to mid-rise frame structures considering soil-structure interaction (SSI). The methodology of the framework is based on examining different MLTs to obtain the highest possible accuracy for prediction. Within the MLT, a sensitivity analysis was conducted on the main SSI parameters to select the most effective input parameters. Multiple limit state criteria were used for the seismic evaluation within the process. A new global seismic assessment ratio was introduced that considers both serviceability and strength aspects by utilizing three different engineering demand parameters (EDPs). The proposed framework is novel because it enables the designer to seismically assess the structure, while simultaneously considering different EDPs and multiple limit states. Moreover, the framework provides recommendations for building component design based on the newly introduced global seismic assessment ratio, which considers different levels of seismic hazards. The proposed framework was validated through comparison using non-linear time history (NLTH) analysis. The results show that the proposed framework provides more accurate results than conventional methods. Finally, the generalization potential of the proposed framework was tested by investigating two different types of structural irregularities, namely, stiffness and mass irregularities. The results from the framework were in good agreement with the NLTH analysis results for the selected case studies, and peak ground acceleration (PGA) was found to be the most influential input parameter in the assessment process for the case study models investigated. The proposed framework shows high generalization potential for low- to mid-rise structures.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号