全文获取类型
收费全文 | 502篇 |
免费 | 12篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 1篇 |
综合类 | 5篇 |
化学工业 | 129篇 |
金属工艺 | 6篇 |
机械仪表 | 5篇 |
建筑科学 | 120篇 |
矿业工程 | 4篇 |
能源动力 | 11篇 |
轻工业 | 107篇 |
水利工程 | 9篇 |
石油天然气 | 9篇 |
武器工业 | 2篇 |
无线电 | 4篇 |
一般工业技术 | 50篇 |
冶金工业 | 33篇 |
原子能技术 | 15篇 |
自动化技术 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 2篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 15篇 |
2013年 | 26篇 |
2012年 | 22篇 |
2011年 | 66篇 |
2010年 | 39篇 |
2009年 | 42篇 |
2008年 | 33篇 |
2007年 | 29篇 |
2006年 | 35篇 |
2005年 | 31篇 |
2004年 | 20篇 |
2003年 | 25篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有517条查询结果,搜索用时 15 毫秒
1.
2.
This paper investigates the effect of chelating agents on the bioavailability of Fe and Cu during anaerobic digestion. The results on metal speciation and methane production in anaerobic serum bottles showed that biomass was able to grow in the presence of citrate 1?mM and nitrilotriacetic acid (NTA) 1?mM, suggesting that the binding sites at the cell surface competed efficiently for the metals with the chelating agents added. The presence of free ethylenediaminetetraacetic acid 1?mM inhibited methanogenesis, and this seemed to be related to a loss in metal uptake capacity. Although the addition of soluble microbial products (SMP) did not change metal distribution in anaerobic systems, it caused an increase in the rate of methane production, and it is believed that direct uptake of Cu-SMP complexes was responsible for this increase. The best protection against Cu toxicity occurred when stoichiometric amounts of NTA, which should complex and solubilize most of the Cu, was added, and it is likely that NTA prevented lethal concentrations of Cu from being adsorbed onto the cell and hence internalized. 相似文献
3.
Andreja ?gajnar Gotvajn Jana Zagorc-Kon?an Tatjana Ti?ler 《Canadian Metallurgical Quarterly》2007,133(1):89-94
The preoxidation of a highly polluted waste pharmaceutical fermentation broth using wet air oxidation (WAO) has been studied as a possible method for the effective removal of organics. The applied (pre)treatment method should enhance the biotreatability of the pharmaceutical fermentation broth in terms of reduced initial toxicity and higher biodegradability. Preliminary experiments in the pilot biological treatment plant were successful only at low organic loads, whereas the system collapses at higher ones. The characterization of the fermentation broth was started by common physicochemical analysis, whereas several bioassays were used to determine its impact on biological treatment plants and the environment. Toxicity prior to and after WAO was determined using the acute Vibrio fischeri test, measurement of inhibition of O2 consumption, and the Daphnia magna acute test. Ready biodegradability of the treated and untreated broth has also been assessed. WAO experiments were accomplished in the 2?L batch reactor at different temperatures (240/280°C) and operating pressures. WAO experiments confirmed reduction of the toxicity toward microorganisms, whereas oxidized wastewater was more toxic to daphnids. Biodegradability of the oxidized broth has also been enhanced. Further work has been focused on designing appropriate combination of WAO and biological processes. 相似文献
4.
Sang-Mok Lee Woo-Jin Chang Ah-Rom Choi Yoon-Mo Koo 《Korean Journal of Chemical Engineering》2005,22(5):687-690
Ionic liquids are compounds that composed only of ions and are liquid at room temperature. Thus, it is normally named room
temperature ionic liquid (RTIL). In this study, the application of RTILs to the extractive fermentation of biomaterials was
investigated as a substitute of organic solvents. The relative toxicity of the RTILs on the growth ofE. coli was tested. The inhibition of cell growth in the presence of various ionic liquids was measured using solid and liquid culture,
and EC50 of each RTILs was calculated. The number of viable and total cells was measured by the number of colonies and optical density,
respectively. Effective concentrations of toxicity (EC50) in these tested systems were similar with conventional solvents, such as acetone, acetonitrile, and ethanol. The viability
ofE. coli was affected by the polarity and ionic properties of ionic liquids. The resistance of the microorganisms against ionic liquids
was different with the cations and anions composing ionic liquids. No general influence of the anionic compound of the ionic
liquids was found on toxicity comparing with distinctive influence of cationic moiety. 相似文献
5.
目的:对肿节风注射液进行异常毒性、溶血与凝聚试验、过敏反应安全性实验评价。方法:根据《中国药典》2010年版一部附录"中药注射剂安全性检查法应用指导原则"的要求及相关项目的技术规范进行试验。结果:按每只小鼠尾静脉注射0.5ml肿节风注射液,结果实验小鼠均无异常反应;溶血与凝聚试验供试品管中的溶液在3小时内不发生溶血和凝聚;按豚鼠腹腔注射0.5ml/只和静脉注射1.0ml/只作为本品的致敏剂量和激发剂量,结果试验豚鼠均未出现过敏反应。结论:本肿节风注射液进行的异常毒性、溶血与凝聚试验和致敏反应的安全性评价符合规定。 相似文献
6.
应用硫酸铵分段沉淀和 Ultrogei AcA_(34)凝胶过滤对破伤风毒进行了提纯,并对形成的离子通道在中毒作用中的功能进行了讨论。提纯的毒素与抗粗制毒素血清形成一条沉淀线,于聚丙烯酰胺凝胶电泳中形成单一的蛋白带,分子量为15万,等电点为5.95,毒力为1~3×10~4MLD/μg 蛋白。给小鼠注射低剂量毒素引起迟发性强直性痉挛;注射高剂量毒素引起快速的类肉毒毒素的松弛性麻痹,直至死亡。应用 Patch clamp 技术,破伤风毒素于人工磷脂膜上形成离子通道。只有当膜两侧存有 pH 梯度时毒素才形成离子通道,因此是 pH 依赖的。通道的电导系数为9 PS。 相似文献
7.
本文的目的是建立直接耐晒宝石蓝的急性毒性微量快速分析方法。通过用基于电阻法细胞计数原理的手持式细胞计数器测定由密度约为1.0×104细胞/ml的酿酒酵母悬液20μl和系列浓度待测染料溶液130μl与2.2倍YPD液体培养基110μl所组成的体系在30℃、150 r/min恒温摇床上震荡培养6 h后的细胞数目,求算出该染料的EC50。结果显示直接耐晒宝石蓝对酿酒酵母的EC50为4995 mg/l,与文献报道的小鼠经口LC50=5 g/kg一致。表明本法可作为传统急性毒性测定的替代方法。 相似文献
8.
The aim of this study was to evaluate the susceptibility of the egg stage of the rice moth Corcyra cephalonica to modified atmospheres (MAs) enriched with CO2 or N2 at 25, 30 and 35 °C combined with various exposure times. The tested modified atmospheres containing CO2 were 20% CO2, 16% O2 and 64% N2; 40% CO2, 12% O2 and 48% N2; 60% CO2, 8% O2 and 32% N2 and 80% CO2, 4% O2 and 16% N2. The tested modified atmospheres containing N2 were 97% N2 and 3% O2 and 98% N2 and 2% O2. The results showed that the hatchability responding to modified atmospheres enriched with either CO2 or N2 decreased significantly with an increase in exposure time, gas content (%) and temperature. All tested combinations provided complete (100%) egg control in less than 4 days. Based on 100% mortality, shorter exposures were obtained with 80% CO2 than with N2 at most tested temperatures. The modified atmospheres enriched with 98% N2 were more effective than 97% N2 against C. cephalonica eggs, especially at 35 °C. It is recommended to use high levels of CO2 in air (80%) and N2 (98%) in controlling 0–24-h-eggs of C. cephalonica within 24–36 h for CO2 and 18–72 h for N2. 相似文献
9.
Flavonoids are a class of phytochemical molecules abundant in many plants, fruits, vegetables, and leaves.
Flavonoids possess a series of significant biological activities, including anticancer, antioxidant, antiviral, and antiinflammatory properties. They become an important source of dietary supplements and natural health products.
Though many studies confirmed the safety of flavonoids, the potential toxicity of flavonoids is still a remarkable field
of research to be explored. The enthusiasm for flavonoids expressed by the public has sometimes overlooked their
toxicity and also consumed the flavonoids exceeding the body requirements. The current review focused on the
potential toxicity of flavonoids to make the public consume flavonoids with caution. This review summarizes the
current toxicity which has been reported in vivo and in vitro experiments. The toxicity involves carcinogenicity and
mutation, liver and kidney toxicity, and the influence on the thyroid and reproductive function and intestinal flora
disorders. The mechanism of toxicity is fully complicated, and current evidence indicates that natural flavonoid
glycosides act on different targets with different doses in vivo and in vitro experiments. Though most kinds of
flavonoids are considered safe, flavonoids proposed as food supplements need to be assessed their tolerable upper
intake level as there have been reports of toxic flavonoids. 相似文献
10.
《Food Control》2014
This paper studies the ozone treatment effect on degradation of aflatoxin B1 (AFB1) in corn with different moisture content (MC). The toxicity of the degradation products (DPs) of the ozone-treated AFB1-Contaminated Corn (ACC) was also evaluated using the human hepatocellular carcinoma cell line (HepG2) as model cells. The degradation rate of AFB1 in corn increases with ozone concentration and treatment time. The results showed that ACC with 13.47% MC was easier to be degraded by ozone than with 20.37% MC. Treated with 90 mg L−1 ozone for 20 min and 40 min, AFB1 in corn with 13.47% MC decreased from 83 μg kg−1 to 18.12 μg kg−1 and 9.9 μg kg−1, respectively, well meeting the China National Standard of AFB1 in corn (20 μg kg−1). In order to evaluate the safety of ozone used on ACC, the impacts of AFB1 as well as untreated and ozone-treated ACC with the same level of AFB1 content on HepG2's survival rate, morphology, and apoptosis were studied. The results showed that ACC had high cell toxicity while the toxicity of ozone-treated ACC had no significant difference with that of the AFB1-free culture solution. It is concluded that ozonation can quickly and effectively degrade AFB1 in corn and diminish ACC's toxicity, and therefore, ozonation is expected to be an effective, fast, and safe method for AFB1 degradation in ACC. 相似文献