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91.
Demographic changes have shaped the nation's past and will continue to shape its future. During the first half of the 1990s, the U.S. population grew, on average, by 2.7 million people each year, reaching 262.8 million in 1995. Population growth is projected to continue for the next 50 years, although at a slower rate. The forecast is for more than 390 million Americans by the year 2050. As the U.S. population grows, it will increasingly become more diverse along many socioeconomic dimensions. This increasing diversity will represent an historic shift in America's racial and ethnic composition with long-range implications for how we view racial issues, how we define racial categories and how the political landscape will be refashioned. By the middle of the 21st century the "minority" population will almost equal the size of the non-Hispanic white population. The minority population grew 14 percent during the first half of the 1990s compared with a 3 percent growth in the non-Hispanic white population. But even within the minority population, growth rates varied. Between 1990 and 1995, the Asian population grew 23 percent, the Hispanic population 20 percent and the African American population increased their numbers by 8 percent. Hispanics are projected to outnumber African Americans within the next 15 years. In part, these demographic changes are shifting because of U.S. immigration policies. Until the early 1960s, immigrants to the United States were primarily of white, European stock. Nowadays, Europeans account for about 20 percent of the immigrants. Three-quarters of legal immigrants in the mid-1990s now come from Latin America, the Caribbean and Asia. The increasing racial and ethnic diversity in the United States will create both challenges and opportunities for U.S. schools and businesses in the future. The magnitude of these numbers and their geographic location will be important factors to consider as we prepare for the 21st century. 相似文献
92.
93.
Cuphea seeds contain large amounts of medium chain (C8 to C14) fatty acids, mainly as triacylglycerols. The biosynthesis of these lipids was studied in vivo by incubating developingCuphea lutea seeds with labeled acetate. Incorporation of label into triacylglycerols and into medium chain fatty acids occurred principally
during the period of endogenous lipid deposition, but some label was encountered in these products even during seed dehydration.
At this later stage palmitate and oleate were the dominant labeled fatty acids. During the period of rapid endogenous lipid
deposition acyl lipids other than triacylglycerols were minor labeled components. The labeling patterns were consistent with
the Kennedy pathway for triacylglycerol biosynthesis. The fatty acid composition of the acyl-CoA pool was similar to the total
lipid fatty acid composition, but the acyl-ACP pool contained relatively more short chain acyl groups. Squalene was labeled
from acetate throughout the period of seed development, but labeled sterols were not detected. Using [2-14C]mevalonic acid lactone as substrate, squalene was the principal labeled product. Small amounts of label were found in free
sterols. However, in terms of mass, free sterol dominated over squalene. The possibility of two independent sites of isoprenoid
biosynthesis in the developing embryo is discussed. 相似文献
94.
Abstract IT governance is critical to most organisations and has an influence on the value generated by IT investments. Unfortunately, IT governance is more aspiration than reality in many organisations. This research seeks to address the dearth of empirical evidence about IT governance in practice, presenting the findings of an IT governance case study in an Australian organisation. Recommendations are provided to assist organisations to maximise potential of IT governance and insights are provided for researchers. 相似文献
95.
Observation of magnetic domains with in-plane magnetisations is demonstrated by scanning near-field optical microscopy (SNOM) in reflection mode. The longitudinal and transverse magneto-optical Kerr effects are employed as the contrast mechanisms; these are observed as either a change in the polarisation of the reflected light or reflectance, depending on magnetisation direction. SNOM images of Co and Ni thin films show magneto-optical contrast depending on polarisation of the incident and detected light. For the smooth cobalt thin films, the orientation for magnetic domains is estimated, based on the correlation between the contrasts in SNOM images obtained in different polarisation configurations and the directions of the magnetic vectors of the incident and reflected light. For the nickel films with pronounced topographic structures, the resulting near-field polarisation dependencies are more complicated, suggesting that the magneto-optical contrast in SNOM images are affected by the topographic cross-talk due to the depolarisation effects on surface topographic features. 相似文献
96.
A controlled soil microcosm study was used to evaluate the performance of selected oil biotransformation indices using samples of Nigerian crude, a blended ballast oil and No. 6 fuel oil. Biotic losses were demonstrated through loss of solvent extractable matter (SEM) and changes in class fraction distribution in weathered soil extracts relative to sterilised controls. GC-EI MS peak identification and quantification was achieved for selected (sigma) n-alkanes, the isoprenoid alkanes norpristane (iC18), pristane (iC19) and phytane (iC20), combined mono-substituted (1-, 2-, 3- and 9-) methylphenanthrenes (sigma methylphenanthrenes), combined dimethylphenanthrenes (sigma dimethylphenanthrenes) and the hopane isomers 17 alpha(H)21 beta(H)-hopane and 17 alpha(H)21 beta(H)-30-norhopane. The [sigma n-alkanes:17 alpha(H)21 beta(H)-hopane] index was most sensitive to oil biotransformation and most accurately reflected depletion of oil from contaminated soils in this study. This index was found to be the most reliable for the No. 6 fuel oil saturates, dropping from 81.9 to 18.1 over the course of the 256-day microcosm study. In terms of sensitivity, and taking into account the results of an ANOVA analysis, the biotransformation indices most sensitive to oil biotransformation were (in order of decreasing sensitivity): [sigma C14-28:17 alpha(H)21 beta(H)-hopane] > [sigma C14-28:sigma dimethylphenanthrenes] > [C18:phytane]. 相似文献
97.
Ecological and aesthetic criticisms of commercial coniferous plantings in the early 20th century, together with growing environmental awareness of issues such as multiple‐use, sustainability and biodiversity, have prompted new policies and approaches to forest management. This paper examines the management and development of Fernworthy Plantation, Devon to illustrate the extent to which the management strategies have changed through time in response to experience, public pressure and policy review. The results of an ecological survey of the vegetation of adjacent moorland and plantation habitats are discussed to establish ecological change in relation to the forest management cycle at the site. 相似文献
98.
Leon Pollard 《Journal of the American Planning Association. American Planning Association》2013,79(2):86-93
Urban activities surveys are workable bases for continuing planner-citizen dialogues. Seeking both to inform and to involve citizens, these exchanges also provide the planner with an avenue of collaboration with his client community. Findings from the surveys may be maintained in an activities base, which includes both quantitative and qualitative data on activities. Policy and planning decisions benefit from activities base data on the concerns and potentials of subcommunities. A pilot study of household activities demonstrates the usefulness and feasibility of the collaborative approach. This approach seems particularly appropriate in light of the wider definition of the planning realm now being recognized. 相似文献
99.
Evidence and belief in regulatory decisions – Incorporating expected utility into decision modelling
J. Li G.J. Davies G. Kendall E. Soane R. Bai S.A. Rocks S.J.T. Pollard 《Expert systems with applications》2012,39(10):8604-8610
Recent changes in the assessment and management of risks has had the effect that greater importance has been placed on relationships between individuals and within groups to inform decision making. In this paper, we provide the theoretical underpinning for an expected utility approach to decision-making. The approach, which is presented using established evidence support logic (TESLA?), integrating the expected utilities in the forming of group decisions. The rationale and basis are described and illustrated through a hypothetical decision context of options for the disposal of animal carcasses that accumulate during disease outbreaks. The approach forms the basis for exploring the richness of risk-based decisions, and representing individual beliefs about the sufficiency of evidence they may advance in support of hypotheses. 相似文献
100.
In this article, it has been shown that under certain circumstances, i.e., in a receiver, it is possible to allow microwave filters to have significant passband insertion loss. Systems analysis of various receiver configurations shows that acceptable noise figures and intercept points may be obtained in receivers containing lossy filters, i.e., ones with low-Q resonators. Thus, the engineering problem is how to develop design techniques for filters that have low-Q resonators, but with acceptable response in terms of selectivity and pass-band flatness. A review of several techniques for bandpass and bandstop filters is presented. 相似文献