全文获取类型
收费全文 | 1301篇 |
免费 | 82篇 |
专业分类
电工技术 | 7篇 |
综合类 | 4篇 |
化学工业 | 447篇 |
金属工艺 | 16篇 |
机械仪表 | 23篇 |
建筑科学 | 53篇 |
能源动力 | 17篇 |
轻工业 | 162篇 |
水利工程 | 11篇 |
石油天然气 | 1篇 |
无线电 | 61篇 |
一般工业技术 | 232篇 |
冶金工业 | 211篇 |
自动化技术 | 138篇 |
出版年
2024年 | 1篇 |
2023年 | 23篇 |
2022年 | 71篇 |
2021年 | 93篇 |
2020年 | 45篇 |
2019年 | 45篇 |
2018年 | 35篇 |
2017年 | 42篇 |
2016年 | 36篇 |
2015年 | 51篇 |
2014年 | 38篇 |
2013年 | 72篇 |
2012年 | 81篇 |
2011年 | 102篇 |
2010年 | 76篇 |
2009年 | 68篇 |
2008年 | 96篇 |
2007年 | 69篇 |
2006年 | 55篇 |
2005年 | 34篇 |
2004年 | 40篇 |
2003年 | 35篇 |
2002年 | 28篇 |
2001年 | 23篇 |
2000年 | 17篇 |
1999年 | 12篇 |
1998年 | 19篇 |
1997年 | 15篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1383条查询结果,搜索用时 15 毫秒
81.
The quantitative effects of beam current-density and sample mass-thickness on the loss of chlorine which occurs from lyophilized solutes of micro-droplets of mineral salt solutions irradiated in an electron probe analyser were studied. Results are reported for chlorine loss from lyophilized deposits with mass-thickness varying between 5 and 50 mg mm?2 for NaCl salts and 5 and 80 mg mm?2 for KCl salts. Electron accelerating voltage was kept constant at 15 kV. The range of beam current-density (I/S, current/sample surface area) was from 0.1 to 1.5 A mm?2. Samples were irradiated for 1200 s. The results show that under some conditions there is a period of stable chlorine signal before chlorine loss occurs. This is observed between 0.1 and 1 A mm?2, for a period which can last several hundred seconds depending on beam current-density and sample mass-thickness. For each value of I/S, however, no stable chlorine signal can be observed for samples whose mass-thickness exceeds a value negatively correlated with I/S. The curves of decrease of characteristic chlorine X-ray signal (expressed as per cent of count rate in the initial counting interval) versus irradiation time can be fitted by the sum of two exponentials with half lives T1 and T2. In NaCl, T1 and T2 values are highly correlated with I/S but not with mass-thickness. In KCl, T1 is correlated only with mass-thickness and T2 only with I/S. Mixing plasma with mineral solutions prevents chlorine loss. 相似文献
82.
Bradizza Clara M.; Maisto Stephen A.; Vincent Paula C.; Stasiewicz Paul R.; Connors Gerard J.; Mercer Nicole D. 《Canadian Metallurgical Quarterly》2009,77(6):1147
Few investigators studying alcohol abuse among individuals with a severe mental illness (SMI) have examined predictors of posttreatment alcohol outcomes. In the present study, a multivariate approach based on a theoretical model was used to study the relationship between psychosocial factors and post-treatment-initiation alcohol use. Predictors of alcohol use outcomes were examined in 278 individuals diagnosed with a current schizophrenia-spectrum or bipolar disorder and an alcohol use disorder (AUD). At 6-months follow-up, 144 of 228 available participants (63%) had good clinical outcomes. The results of structural equation modeling indicated that type of pretreatment residential setting was directly related to treatment, with participants who lived in supervised settings (41%) reporting significantly more days of treatment (β = .34, p 相似文献
83.
Lochman John E.; Boxmeyer Caroline; Powell Nicole; Qu Lixin; Wells Karen; Windle Michael 《Canadian Metallurgical Quarterly》2009,77(3):397
This study examined an important but rarely investigated aspect of the dissemination process: the intensity of training provided to practitioners. Counselors in 57 schools were randomly assigned to 1 of 3 conditions: Coping Power–training plus feedback (CP-TF), Coping Power–basic training (CP-BT), or a comparison condition. CP-TF counselors produced reductions in children’s externalizing behavior problems and improvements in children’s social and academic skills in comparison to results for target children in both the comparison and the CP-BT conditions. Training intensity was critical for successful dissemination, although the implementation mechanism underlying this effect remains unclear, as condition effects were not significant for completion of session objectives but were significant for the quality of counselors’ engagement with children. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
84.
Four studies present the validation of a self-report scale capturing academic entitlement, which is defined as the tendency to possess an expectation of academic success without a sense of personal responsibility for achieving that success. The Academic Entitlement scale possesses a 2-factor structure (Study 1); 10 items measure students’ Externalized Responsibility for their academic success, and 5 items measure students’ self-serving Entitled Expectations about professors and course policies. In Study 2, the Externalized Responsibility subscale correlated positively with related measures of entitlement, grandiosity, and narcissism, and it was negatively related to self-esteem, personal control, need for cognition, agreeableness, and conscientiousness. In Study 3, participants rated various responses to academic situations selected by university instructors as highly inappropriate or highly appropriate. The Academic Entitlement scale predicted students’ ratings of the appropriateness of these student behaviors as well as the likelihood that they themselves would engage in these behaviors. In a laboratory setting, individuals with high Academic Entitlement scores evaluated the researcher more negatively than those with low Academic Entitlement scores (Study 4). Practical applications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
86.
Nicole Schmidt 《Datenschutz und Datensicherheit - DuD》2009,33(2):107-109
Der BGH hat am 16.07.2008 (DuD 2008, 751) die Einwilligungsl?sung für die Zusendung von Werbung per Post, SMS oder E-Mail von Unternehmen an Kunden im Zusammenhang mit der Kundenkarte Payback bewertet. Als Konsequenz ist nun der Gesetzgeber gefordert, einen einheitlichen Einwilligungsstandard festzulegen. 相似文献
87.
Haris Doukas Alexandra G. Papadopoulou Christos Nychtis John Psarras Nicole van Beeck 《Renewable & Sustainable Energy Reviews》2009,13(3):682-688
The European Union (EU) from the beginning of 2007 has focused its emphasis on the development of a new policy that puts energy back at the heart of EU action. Indeed, it has very often been stated that the difficulty and complexity of achieving green energy targets in the EU will require strengthened measures to promote implementation of new energy technologies (NET), as well as measures to support the related energy Research and Technology Development (R&TD). Often forgotten is the fact, that most of all, a European-wide co-ordinated forum is needed to continuously develop and sophisticate the monitoring and methodology results, bringing together specialised statisticians, energy researchers and experts on energy socio-economics. Today a nebulous picture prevails on the existence of categorized data with regards to energy Research and Technology Development (R&TD) expenditure. In this context, aim of this paper is the presentation of energy R&TD data collection strategies, as well as the related findings for the Greek energy market. 相似文献
88.
Nicole Robinson 《建设机械技术与管理》2009,(12):I0043-I0044
一种新型超重吨位轮式起重机的伸缩臂如此大。以至于要分成两部分来运输才行.且其中的一段需要特种运输车来运输。 相似文献
89.
Effects of dietary trielaidin upon the alkenyl chain profile of plasmalogens were studied using heart mitochondria of rats
fed a semi-purified diet containing 10% of fat supplement in which elaidic acid accounted for 69% of total fatty acids. Alkyl
substituted dioxane (ASD) derivatives of the alkenyl groups of plasmalogens were prepared and analyzed by silver nitrate TLC
and by GLC on different phases (BDS and OV-275). After two months of feeding the experimental diet, 40% of the ASD contained
atrans-octadecenyl chain, suggesting that dietary elaidic acid was reduced in vivo to the corresponding alcohol and incorporated
into plasmalogens. There was a simultaneous decrease in the percentage of ASD containing saturated chains, but the percentage
of ASD substituted withcis-octadecenyl chains was not significantly affected. These observations suggested that elaidic acid may compete with saturated
fatty acids, but not withcis-octadecenoic acids during the plasmalogen biosynthesis. Feeding trielaidin did not seem to have any significant influence
on the relative proportions of plasmalogens, which accounted for 11–12%, on a phosphorus basis, of total heart mitochondria
phospholipids. 相似文献
90.
Pure cardiolipins (1,3-diphosphatidylglycerol) were prepared from mitochondria of heart, liver and kidney from 21-day-old
male Wistar rats and submitted toNaja naja venom phospholipase A2 (EC 3.1.1.4) action. Incubation conditions were controlled carefully, and a complete hydrolysis of cardiolipin to lysocardiolipin
{di [1 (1″) acylsn-glycero-3-phosphoryl] 1′, 3′-sn-glycerol} and fatty acids from positions 2 (2″) was obtained in less than two hr practically without side reactions. Cardiolipins
from the three organs contained low levels of saturated fatty acids; stearic acid accounted for 0.4–0.7% and palmitic acid
for 1.4–3.5% of total fatty acids. These percentages apparently depended on the organ. In all three cases, linoleic acid was
the major component, but its percentage varied from 62–78% of total fatty acids. Acyl chains linked to positions 1 (1″) of
all three cardiolipin preparations exhibited a similar pattern; they were composed of linoleic acid for 85–89%. This fatty
acid also was the main component esterified at position 2 (2″), but its percentage was much more variable: from 39.8% in heart
to 51.2% in kidney and 67.8% in liver mitochondria. The remaining acids comprised octadecenoic and polyunsaturated fatty acids
with more than 18 carbon atoms in different proportions. As opposed to other phospholipids,cis-vaccenic acid, and not oleic acid, was the main octadecenoic acid present in cardiolipins.
Octadecenoic acids were nine- to 10-fold more concentrated at positions 2 (2″) than at positions 1 (1″). The percentage ofcis-vaccenic acid was four- to five-fold higher than that of oleic acid at positions 2 (2″), whereas oleic acid dominated at
positions 1 (1″). From results presented in this study and selected literature data, it may be concluded that fatty acids
are asymmetrically distributed in cardiolipins of different origins, with linoleic acid showing a definite preference for
position 1 (1″). 相似文献