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   764篇
  免费   32篇
电工技术   9篇
综合类   1篇
化学工业   330篇
金属工艺   18篇
机械仪表   16篇
建筑科学   7篇
矿业工程   1篇
能源动力   11篇
轻工业   55篇
水利工程   3篇
石油天然气   2篇
无线电   41篇
一般工业技术   110篇
冶金工业   54篇
自动化技术   138篇
  2024年   2篇
  2023年   8篇
  2022年   67篇
  2021年   105篇
  2020年   31篇
  2019年   18篇
  2018年   28篇
  2017年   24篇
  2016年   35篇
  2015年   23篇
  2014年   40篇
  2013年   73篇
  2012年   35篇
  2011年   46篇
  2010年   31篇
  2009年   28篇
  2008年   23篇
  2007年   24篇
  2006年   20篇
  2005年   18篇
  2004年   15篇
  2003年   6篇
  2002年   8篇
  2001年   5篇
  1999年   6篇
  1998年   3篇
  1997年   3篇
  1996年   4篇
  1995年   4篇
  1994年   2篇
  1993年   8篇
  1992年   2篇
  1991年   5篇
  1990年   7篇
  1989年   5篇
  1988年   4篇
  1987年   1篇
  1986年   2篇
  1985年   5篇
  1984年   1篇
  1983年   5篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1978年   1篇
  1975年   3篇
  1972年   1篇
  1967年   3篇
  1964年   1篇
排序方式: 共有796条查询结果,搜索用时 15 毫秒
101.
102.
Obesity is characterized by altered gut homeostasis, including dysbiosis and increased gut permeability closely linked to the development of metabolic disorders. Milk oligosaccharides are complex sugars that selectively enhance the growth of specific beneficial bacteria in the gastrointestinal tract and could be used as prebiotics. The aim of the study was to demonstrate the effects of bovine milk oligosaccharides (BMO) and Bifidobacterium longum ssp. infantis (B. infantis) on restoring diet-induced obesity intestinal microbiota and barrier function defects in mice. Male C57/BL6 mice were fed a Western diet (WD, 40% fat/kcal) or normal chow (C, 14% fat/kcal) for 7 wk. During the final 2 wk of the study, the diet of a subgroup of WD-fed mice was supplemented with BMO (7% wt/wt). Weekly gavage of B. infantis was performed in all mice starting at wk 3, yet B. infantis could not be detected in any luminal contents when mice were killed. Supplementation of the WD with BMO normalized the cecal and colonic microbiota with increased abundance of Lactobacillus compared with both WD and C mice and restoration of Allobaculum and Ruminococcus levels to that of C mice. The BMO supplementation reduced WD-induced increase in paracellular and transcellular flux in the large intestine as well as mRNA levels of the inflammatory marker tumor necrosis factor α. In conclusion, BMO are promising prebiotics to modulate gut microbiota and intestinal barrier function for enhanced health.  相似文献   
103.
Our goal is to obtain a new food supplement — a chemopreventive preparation derived from selenium (Se)-enriched Lentinula edodes mycelium. In the present study the bioavailability of selenium from Se-enriched mycelium preparations was tested in vitro and in vivo. Three different preparations of selenated mycelium were compared: dried mycelium, lyophilized mycelium, and lyophilized-autolyzed mycelium. In vitro, estimated Se bioavailabilities were 60%, 82%, and 98%, respectively. In vivo bioavailability was determined in rats. As reference, sodium selenite and Se yeast formulations were used at an Se-equivalent dose. The pharmacokinetic data for tested mycelial preparations suggest a rapid but incomplete Se absorption, and rapid elimination, without risk of accumulation. The speciation of selenium in Se-enriched mycelial cultures was carried out by specific oxido-reduction reactions. For tested mycelium the main part of Se was in the 0 and IV oxidation states in inorganic form or combined in a lipid or carbohydrate structure, about 47% was in the –II state in Se-amino acids or in other undefined water- or alcohol soluble organic compounds. Differences in pharmacokinetic data for Se yeast and L. edodes mycelial formulations probably arise from differences in Se speciation. Our data suggest that formulations of selenized Lentinula edodes mycelium could be used in chemoprevention as food supplements.  相似文献   
104.
Searching for effects of candidate gene polymorphisms on fatness traits is an important goal for pig industry. In this study we evaluated polymorphism of four porcine genes involved in energy metabolism (RETN, UCP1, UCP3 and ADRB3). Moreover, their association with fat deposition traits was analyzed in two breeds (Polish Landrace, Polish Large White) and a Polish synthetic line (L990). Altogether, five SNPs were identified, including two novel ones in the 5′-flanking region of the RETN gene and a novel missense substitution in the UCP3. Distribution of these polymorphisms in the studied five breeds and the synthetic line was not uniform. Two of the analyzed SNPs: g.−178G > A in the RETN and g.946C > T in the UCP3 gene revealed a significant association with abdominal fat weight or backfat thickness. Such associations were not observed for the UCP1 or ADRB3 gene polymorphisms. Our study showed that polymorphisms of the UCP3 and RETN genes are potentially associated with porcine fatness traits.  相似文献   
105.
Thirteen edible oils: sunflower, avocado, hemp, high-linolenic flax, low-linolenic flax, safflower, walnut, roasted sesame, rice, corn, rapeseed, pumpkin seed, and hazel were studied in this work. Their fatty acid composition, iodine, acidic, peroxide, and saponification values were determined. Infrared and Raman spectra of the oils were recorded in the range 400–3200 cm?1. The integral intensities of the bands at about 1655 and 2852 cm?1 corresponding to ν(C=C) and ν(CH2) vibrations were evaluated and used to construct a relationship between the spectroscopic data and the iodine value. The following linear dependencies were obtained: Iν(C=C)/Iν(CH2) = 7.449 × 10?4 × iodine value – 0.0339 and Iν(C=C)/Iν(CH2) = 9.299 × 10?4 × iodine value – 0.023 for the infrared and Raman spectra with a correlation coefficient 0.988 and 0.976, respectively. These calibration lines can be used to determine the iodine value for oils with unknown unsaturation level, and may be applied for margarines and other fatty materials.  相似文献   
106.
Properties of capacitors working with the same carbon electrodes (activated carbon cloth) and three types of electrolytes: aqueous, organic and ionic liquids were compared. Capacitors filled with ionic liquids worked at a potential difference of 3.5 V, their solutions in AN and PC were charged up to the potential difference of 3 V, classical organic systems to 2.5 V and aqueous to 1 V. Cyclic voltammetry, galvanostatic charging/discharging and impedance spectroscopy were used to characterize these capacitors. The highest specific energy was recorded for the device working with ionic liquids, while the highest power is characteristic for the device filled with aqueous H2SO4 electrolyte. Aqueous electrolytes led to energy density an order of magnitude lower in comparison to that characteristic of ionic liquids.  相似文献   
107.
Fifteen wild yeast strains were isolated in two factories of a lager brewing company in Poland. Their identification with API 32C system showed mainly the presence of Candida sake species (7/15). To differentiate the isolates, randomly amplified polymorphic DNA (RAPD) with (GTG)(5), (GAC)(5), (GACA)(4) microsatellite primers and M13 core sequence (5'-GAG GGT GGC GGT TCT-3') were chosen. The results of patterns similarity are presented as dendrograms for each RAPD analysis and for overall patterns. On the overall patterns, all isolates identified as C. sake, except Strain No. 1, were regrouped in one cluster. Collection strain C. sake CBS 617 was similar in 46% to the cluster with six isolates (Strain Nos. 3, 6, 8, 11, 13, 14). The second reference strain C. sake CBS 159 and the Strain No. 1 were regrouped with other Candida species (collection strains) showing, respectively, only 20% and 42% of similarity to other C. sake strains. The similarity based on the overall dendrogram between isolate Nos. 3, 6, 8, 11, 13, 14 and C. sake CBS 617 was 49%. Between those strains and other Candida, the similarity was only 37%.  相似文献   
108.
The goal of the presented studies was to investigate speciation and bioavailability of iodine from chicken eggs versus iodized kitchen salt with an in vitro method. Determination of iodine total content in chicken eggs and iodized kitchen salt was carried out by inductively coupled plasma mass spectrometry (ICP MS). The majority of iodine was accumulated in the yolk—the concentration was even 37 times higher than in white. Chicken eggs were treated with buffer (Tris HCl pH = 7.5) and enzymatic extraction media and analyzed by size exclusion chromatography hyphenated with inductively coupled plasma mass spectrometry (SEC ICP MS). The enzymatic extraction being an in vitro bioavailability assessment method was based on two-stage digestion model simulating gastric (pepsin digestion) and intestinal (pancreatin digestion) juices. Speciation analyses along with bioavailability studies presented iodide as the major form in chicken eggs. The bioavailability was established as 33% from white and 10% from yolk and decreased with longer time of boiling. It allows to suggest that the majority of iodine remains in forms bound to non-digestible coagulated and water-insoluble proteins.  相似文献   
109.
This paper studies the correctness of distributed systems made up of replicated processes that communicate by message passing. Processes are described within the divergence model of CSP. The notion of correctness introduced is based on a relation that formally expresses the conformance of an implementation process with the target process it is intended to implement. A weak and a strong version of the relation are introduced, aimed at treating acyclic and cyclic process networks respectively. Both allow the study of (total) correctness and may cope with non-deterministic targets and implementations.We then show how a target process may be implemented (in the formal sense introduced) by replicating it in a set of copies, a majority of which is non-faulty.  相似文献   
110.
In the present article a measurement method of particle size distributions (PSD) in industrial installations which use a dispersed phase of low concentration (like spray dryers or spray scrubbers) is introduced. A new type of inline-measurement system has been developed and designed to work in spray drying conditions. A standard digital camera is used to record shadows of flowing particles inside the spray drying chamber. Collected images were analyzed by a newly developed software which recognizes particles only in the focus area and eliminates several types of artifacts. The constructed prototype of the PSD inline-analyzer was installed and used to monitor large laboratory scale spray dryer. All data collected by the designed system during the spray drying experiments were compared with data measured with an offline reference system to show accuracy of the new measurement technique.  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