全文获取类型
收费全文 | 8856篇 |
免费 | 563篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 70篇 |
综合类 | 11篇 |
化学工业 | 3587篇 |
金属工艺 | 91篇 |
机械仪表 | 114篇 |
建筑科学 | 367篇 |
矿业工程 | 42篇 |
能源动力 | 198篇 |
轻工业 | 1870篇 |
水利工程 | 61篇 |
石油天然气 | 54篇 |
无线电 | 347篇 |
一般工业技术 | 1260篇 |
冶金工业 | 514篇 |
原子能技术 | 24篇 |
自动化技术 | 820篇 |
出版年
2024年 | 21篇 |
2023年 | 132篇 |
2022年 | 781篇 |
2021年 | 902篇 |
2020年 | 293篇 |
2019年 | 265篇 |
2018年 | 324篇 |
2017年 | 281篇 |
2016年 | 349篇 |
2015年 | 296篇 |
2014年 | 366篇 |
2013年 | 623篇 |
2012年 | 523篇 |
2011年 | 622篇 |
2010年 | 403篇 |
2009年 | 419篇 |
2008年 | 408篇 |
2007年 | 370篇 |
2006年 | 305篇 |
2005年 | 233篇 |
2004年 | 208篇 |
2003年 | 182篇 |
2002年 | 156篇 |
2001年 | 84篇 |
2000年 | 66篇 |
1999年 | 81篇 |
1998年 | 66篇 |
1997年 | 70篇 |
1996年 | 72篇 |
1995年 | 57篇 |
1994年 | 61篇 |
1993年 | 53篇 |
1992年 | 41篇 |
1991年 | 21篇 |
1990年 | 29篇 |
1989年 | 20篇 |
1988年 | 28篇 |
1987年 | 17篇 |
1986年 | 14篇 |
1985年 | 24篇 |
1984年 | 21篇 |
1983年 | 26篇 |
1982年 | 12篇 |
1981年 | 15篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1974年 | 6篇 |
1966年 | 6篇 |
排序方式: 共有9430条查询结果,搜索用时 0 毫秒
951.
Anna M. Balinova Rositsa I. Mladenova Deyana D. Shtereva 《Food Additives & Contaminants》2007,24(8):896-901
The effects of storage intervals and of milling procedures on dissipation of deltamethrin residues in post-harvest treated wheat grain were studied with the aim to obtain scientific data on compliance of the processed products with the safety requirements concerning baby foods. The insecticide formulation was applied on stored wheat at a recommended rate of active ingredient of 0.5 mg kg-1 and at a higher rate of 4 mg kg-1, performing the highest protective effect. The dissipation of residues and their distribution in different fractions of the milled grain were studied after various storage intervals, from 7 to 270 days after treatment. Eight fractions—bran, semolina, three types of groats, and three types of flour—were collected after milling of grain and analysed for determination of pesticide residues. The residues were determined by gas chromatography characterized by the limit of determination of 0.005 mg kg-1, low enough for enforcement of the maximum residue level of 0.01 mg kg-1 established by the European Commission Directive for any pesticide in cereal-based foods. Deltamethrin applied post-harvest on wheat as grain protectant was distinguished by low rate of degradation on the grain under practical storage conditions. One hundred and eighty days after treatment at an application rate of 0.5 mg kg-1, the residues were between 0.03 and 0.2 mg kg-1 in the various types of flour. Two hundred and seventy days after treatment at a rate of 4 mg kg-1, the residues in the flour were in the range of 0.4-1.5 mg kg-1. 相似文献
952.
Chambless Dianne L.; Fauerbach James A.; Floyd Frank J.; Wilson Kimberly A.; Remen Anna L.; Renneberg Babette 《Canadian Metallurgical Quarterly》2002,111(3):502
Married couples with a female agoraphobic spouse (n = 22) were compared with demographically similar community control couples (n = 21) on self-report and observational measures of marital interaction. Consistent with hypotheses, husbands of agoraphobic women were more critical of their wives than were control husbands, and clinical couples were less likely to engage in positive problem solution than control couples. Contrary to hypothesis, clinical husbands were not less supportive than control husbands. Where general measures of marital distress were concerned, clinical couples, relative to control couples, evinced more distress by self-report, by their higher rate of negative nonverbal behavior, and by their longer sequences of negative exchanges. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
953.
An architecture based on emulated LAN is proposed which can efficiently provide the required bandwidth of mobiles as they migrate between cells. The proposed solution (1) ensures the required bandwidth of a mobile when its path changes because of handoff, (2) efficiently reserves bandwidth resulting in higher bandwidth/network utilization, (3) has the flexibility of reserving bandwidth depending upon the mobility (rate of handoff). Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
954.
Anna Gliszczyńska-Świgło Alina Kałużewicz Katarzyna Lemańska Mikołaj Knaflewski Bożena Tyrakowska 《Food chemistry》2007,100(1):241-245
The effect of solar radiation on the quercetin and kaempferol contents in the inflorescence of three broccoli cultivars (‘Lord’, ‘Marathon’ and ‘Fiesta’) was investigated from 1999 to 2001. Great differences in the contents of both flavonols, dependent on growing time and cultivar, were found. Quercetin and kaempferol contents varied from 14.3 to 81.0 mg kg−1 f.w. and from 35.9 to 213 mg kg−1 f.w., respectively. Inflorescences of the cultivar ‘Lord’ were characterised by the highest mean content of quercetin and those of cultivar ‘Fiesta’ of kaempferol. The contents of both flavonols were highly positively correlated with total solar radiation in the period from planting to the harvest of broccoli inflorescences. 相似文献
955.
Race, class, and the attributional process. 总被引:1,自引:0,他引:1
Two experiments examined the process and content of attributional thinking in Black and White children who differed in socioeconomic status (SES). In Exp I, 171 7th graders subdivided into middle-SES Black, middle-SES White, low-SES Black, and low-SES White groups imagined that they succeeded or failed at an examination, with the cause of the outcome specified. Their perceptions of the dimensional properties of causes (locus, stability, and controllability), expectancy for success, teacher evaluation, and affective reactions were reported. Similar judgments were made in Exp II, with 148 of the Ss from Exp I, in response to actual rather than hypothetical success and failure, and Ss' causal attributions for their performance were reported. Analyses revealed that Blacks did not display a less adaptive attributional pattern than did Whites following actual performance, and no differences existed in Ss' understanding of the meaning (dimensional placement) of causes. A linkage between the locus of causes and affect also was documented in all race?×?SES groups. In contrast, race and class differences occurred in Ss' perceptions of predicted stability–expectancy and controllability–evaluation causal linkages. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
956.
957.
Chantal Seignez Anna Atti Nevenka Adler Paul Péringer 《Canadian Metallurgical Quarterly》2002,128(4):360-366
In this paper the effect of operating parameters on biotrickling filter performance degrading chlorobenzene and o-dichlorobenzene mixture were studied. The large laboratory scale biofilter, total volume 40 L, filled with inert packing material was used. The biomass adaptation and cultivation were performed in a batch fermentor and were used to inoculate the biotrickling filter. After a starting period, the influence of the substrate load increase, liquid recirculation flow rate, and empty bed retention time on elimination capacity and removal efficiency were found. The most important recirculation liquid parameters were analyzed every day, that is: concentration of metabolites, dissolved organic carbon, nitrate, chloride, and biomass. A good correlation was found between intermediate concentration and the removal efficiency of the biotrickling filter. The measurements of the absorbance, very easy and rapid, can be used as a control parameter of the biofiltration efficiency. 相似文献
958.
Christos G. Papadimitriou Anna Vafopoulou-Mastrojiannaki Sofia Vieira Silva Ana-Maria Gomes Francisco Xavier Malcata Efstathios Alichanidis 《Food chemistry》2007,105(2):647-656
Two sets of traditional Greek sheep milk yoghurt were produced: the first one (YC) using normal yoghurt culture (Lactobacillus delbrueckii subsp. bulgaricus ?10.13 and Streptococcus thermophilus ?10.7) and the second (PR) with the same normal culture mixed with Lactobacillus paracasei subsp. paracasei DC412. YC and PR had similar physicochemical properties and proteolysis patterns throughout storage. Both products showed similar peptide profiles by RP-HPLC but quantitative differences were observed in respect to storage time. Single-strain cultures of the microorganisms used showed similar peptide profiles for both lactobacilli, yet L. delbrueckii subsp. bulgaricus was the most proteolytic of all three microorganisms. The peptide content and the ACE-inhibitory activity of the water-soluble extracts of yoghurts, YC and PR, increased throughout storage. Major peptides were identified from yoghurt PR and from the separate cultures of L. delbrueckii subsp. bulgaricus and L. paracasei subsp. paracasei. Most of these peptides were derived from β-casein. A peptide, β-CN f114-121, with well-established ACE-inhibitory and opiate-like activity was identified in yoghurt PR. Further identified peptides were regarded as potential ACE-inhibitors according to their sequence. 相似文献
959.
Wine ageing in wood barrels is a traditional practice in quality wine-making areas. It is generally believed that the organoleptic characteristics of wines aged in barrels are deeply influenced by wood geographical origin, as well as by age of barrels (new or used). 相似文献
960.