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71.
Grid Data Management: Open Problems and New Issues 总被引:3,自引:0,他引:3
Initially developed for the scientific community, Grid computing is now gaining much interest in important areas such as enterprise
information systems. This makes data management critical since the techniques must scale up while addressing the autonomy,
dynamicity and heterogeneity of the data sources. In this paper, we discuss the main open problems and new issues related
to Grid data management. We first recall the main principles behind data management in distributed systems and the basic techniques.
Then we make precise the requirements for Grid data management. Finally, we introduce the main techniques needed to address
these requirements. This implies revisiting distributed database techniques in major ways, in particular, using P2P techniques.
Work partially funded by ARA “Massive Data” of the French ministry of research (project Respire), the European Strep Grid4All
project, the CAPES–COFECUB Daad project and the CNPq–INRIA Gridata project. 相似文献
72.
73.
Esther Perales Francisco M. Martínez‐Verdú Valentín Viqueira Jesús Fernández‐Reche José A. Díaz Joan Uroz 《Color research and application》2009,34(4):330-336
In this work, we have studied the relationship among the colorimetric properties of different types of paper, having different finishing and grammage. Their color reproduction capability has also been analyzed by using the same printing technology (inkjet printing). On the one hand, we have plotted CIELAB data under the illuminant D50 into constant lightness and hue‐angle planes to be compared with MacAdam limits and with Pointer's real‐world surface color. On the other hand, we have calculated the volume gamut of the color solid associated to each color paper gamut. Analyzing the results, we have checked that there is not any clear relationship among the colorimetric properties of paper (for instance, CIE whiteness index, etc.) and the color gamut volume associated. However, the colorimetric parameters associated to the printed sample showed a quite good linear correlation between the minimum lightness (or the maximum blackness value) of the printed color chart and the color gamut volume. In particular, the greatest color gamut volume corresponds to the glossy papers taking into account this correlation for inkjet printing. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 330–336, 2009 相似文献
74.
Bielak Allison A. M.; Hultsch David F.; Strauss Esther; MacDonald Stuart W. S.; Hunter Michael A. 《Canadian Metallurgical Quarterly》2010,25(3):575
In this study, the authors addressed the longitudinal nature of intraindividual variability over 3 years. A sample of 304 community-dwelling older adults, initially between the ages of 64 and 92 years, completed 4 waves of annual testing on a battery of accuracy- and latency-based tests covering a wide range of cognitive complexity. Increases in response-time inconsistency on moderately and highly complex tasks were associated with increasing age, but there were significant individual differences in change across the entire sample. The time-varying covariation between cognition and inconsistency was significant across the 1-year intervals and remained stable across both time and age. On occasions when intraindividual variability was high, participants' cognitive performance was correspondingly low. The strength of the coupling relationship was greater for more fluid cognitive domains such as memory, reasoning, and processing speed than for more crystallized domains such as verbal ability. Variability based on moderately and highly complex tasks provided the strongest prediction. These results suggest that intraindividual variability is highly sensitive to even subtle changes in cognitive ability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
75.
Muthuraj Esther Leena Preethi Thiripuranthagan Sivakumar Muthiahpillai Palanichami 《Catalysis communications》2010,11(10):876-879
Fe/Al-MCM-41 (Si/Al = 25, 50, 75 and 100) were synthesized. Their catalytic activity was evaluated towards benzylation of benzene with benzyl chloride in liquid phase. The catalytic activity of Fe/Al-MCM-41(25) was higher than the other catalysts. Diphenylmethane(DPM) was obtained as the major product with 100% selectivity and with 100% conversion of benzyl chloride under optimum condition. The effect of temperature and the feed ratio, on the activity of Fe/Al-MCM-41(25) and selectivity towards DPM was studied and a possible reaction mechanism was proposed. 相似文献
76.
Dodge Kenneth A.; McClaskey Cynthia L.; Feldman Esther 《Canadian Metallurgical Quarterly》1985,53(3):344
Generated and evaluated a taxonomy of the situations and tasks most likely to lead deviant children to experience social difficulties. In Study 1, elementary school teachers and clinicians were asked to notice such situations as they occurred. The outcome was a 44-item taxonomy of problematic social situations for children. This survey was administered to teachers of 45 socially rejected children (79% male) from Grades 3–5 and 39 adaptive children of the opposite sociometric criteria who were matched by sex and age to the rejected Ss. The survey was found to have high internal consistency and high test–retest reliability. Six situation types emerged as factors in analyses: Peer Group Entry, Response to Peer Provocations, Response to Failure, Response to Success, Social Expectations, and Teacher Expectations. Teachers rated the rejected group as having more problems than the adaptive group in each situation, but particularly in Response to Peer Provocations and Teacher Expectations. In Study 2, 15 items within the 6 factors were presented in a hypothetical format to 39 clinic-referred rejected aggressive children (77% males) from Grades 3–5 and 34 adaptive children selected by opposite criteria and matched by sex and age to the rejected aggressive Ss, who were asked to role play their responses. The items, in particular the provocation items, again differentiated the 2 groups. Sex and age differences were also found. The usefulness of this taxonomy in a 3-step model of clinical assessment is proposed. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
María E. Len-Ríos Shelly Rodgers Esther Thorson Doyle Yoon 《The Journal of communication》2005,55(1):152-168
This study uses a feminist framework of masculine cultural hegemony to examine the representation of women in two newspapers—a medium-sized newspaper (Study 1) and a larger newspaper (Study 2). Surveys gauged news staff and news reader perceptions of female representation in news content to determine if perceptions matched content-analysis findings. Content-analysis results revealed a greater proportion of males than females in both content and photos for both studies. Female staffers were more likely than their male counterparts to perceive this disparity, and news readers perceived an even greater disparity than the news staff. News staffs were less likely to perceive disparities in the editorial, travel, and entertainment sections. We discuss the findings in relation to cultural hegemony and the representation of women in the news. 相似文献
78.
Sergio M. Bonesi Esther Carbonell Hermenegildo Garcia Maurizio Fagnoni Angelo Albini 《Applied catalysis. B, Environmental》2008,79(4):368-375
Solid photocatalysts in which the 2,4,6-triphenylpyrylium (TP) or 2,4,6-triphenylthiapyrylium cation (TTP) are encapsulated within zeolite Y or deposited on mesoporous silica are used as photosensitizers for the oxidation of sulfides, both aromatic and aliphatic, in solvents of various polarity. Contrary to the same cations in solution, these solid sensitizers are not significantly degraded during operation. An effective oxygenation takes place leading to sulfoxides, disulfides, sulfinic and sulfenic esters as well as sulfonic acids. This large scope method shows a limited dependence on the substrate structure and on conditions and is suitable for the abatement of sulfur-containing pollutants. 相似文献
79.
A brief proton pulse technique, based on photo-excitation of pyranine, was employed for measuring the protonation dynamics of cytochrome c in aqueous solutions. Time-resolved monitoring of the protonation state of the pyranine anion yielded detailed information from which the temporal state protonation of the surface carboxylates and histidine residues were deduced. The surface groups were found to be coupled by electrostatic interaction where the state of protonation of one affects the pK of the others. In the same sense, altering the charge distribution of a protein by a redox reaction affects the reactivity of the surface groups with protons in the bulk. The surface groups can exchange protons among themselves at a very high rate. The velocities of these reactions are functions of the connectivity between the proton binding sites. A single proton exchange reaction between the surface groups could be identified as the proton exchange between H26 and E44. The reaction is fast and affected by the redox state of the protein. It is proposed that the enhanced rate of this reaction is coupled with transient conformational changes that are not noticeable in time-averaging measurements such as X-ray diffraction or NMR. 相似文献
80.
Concentrations and determinants of organochlorine levels among pregnant women in Eastern Spain 总被引:1,自引:0,他引:1
Sabrina Llop Ferran Ballester Esther Vizcaino Maria-Jose Lopez-Espinosa Marisa Rebagliato Alfredo Marco Joan O. Grimalt 《The Science of the total environment》2010,408(23):5758-5767
Persistent organic pollutants (POPs) comprise a large variety of toxic substances with ample distribution. While exposure to these toxins occurs mainly through diet, maternal POP levels may be influenced by certain sociodemographic, environmental, or lifestyle factors. This is important given that these substances may have adverse effects on fetal development. The aim of this study is to examine the sociodemographic, environmental, lifestyle, and dietary determinants of the levels of hexachlorobenzene (HCB), b-hexachlorocyclohexane (b-HCH), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4′-DDT), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (4,4′-DDE), and polychlorinated biphenyls (PCB congeners 118, 138, 153, 180) measured in the blood of pregnant women participating in a mother-child cohort study conducted in Valencia (Spain).The study population consisted of 541 pregnant women who formed part of the INMA (Childhood and the Environment) cohort (2004-2006). POP levels were determined in blood taken during the 12th week of pregnancy with the aid of gas chromatography with electron capture detection. Sociodemographic, environmental, and dietary information was obtained from a questionnaire. Multivariate Tobit regression models were constructed in order to assess the association between POP levels and selected covariates.The results showed that all the women had detectable levels of at least one of these compounds while in 43% of the subjects, all eight compounds were detected. The compounds found in the greatest number of women were 4,4′-DDE (100%) and PCBs 153 and 180 (95%). The most important determinants of high POP levels were the mother's age, country of origin, increased body mass index, and number of weeks of breastfeeding after previous pregnancies. With regard to diet, 4,4′-DDT and 4,4′-DDE levels increased with the intake of meat, fruit, and cereal. PCB 153 levels increased with the intake of seafood. The levels of HCB, b-HCH, 4,4′-DDT, and 4,4′-DDE observed in this study were slightly higher than in other studies, whereas the PCB levels were similar. 相似文献