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排序方式: 共有1697条查询结果,搜索用时 15 毫秒
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William W. Bowerman Amy S. Roe Michael J. Gilbertson David A. Best James G. Sikarskie Rachel S. Mitchell Cheryl L. Summer 《Lakes & Reservoirs: Research and Management》2002,7(3):183-187
The bald eagle (Haliaeetus leucocephalus) is one of the most studied birds of North America, and a great amount of natural life‐history information, including the response of various stressors on the eagles' ability to reproduce, are well known. In Michigan, the eagle has been chosen to track the trends of bioaccumulative compounds of concern across watersheds in the state. The state has been divided into major watersheds, and 20% of these are surveyed each year. A control area in northern Minnesota, Voyageurs National Park, is also sampled annually. We report here on the methods used, the preliminary results of the 1999 field season, and how differences in mercury concentrations varied over a 10‐year period. Mercury in feathers of nestling eagles declined over time only in Lakes Michigan and Huron, but have not decreased among other subpopulations in Michigan. Concentrations of polychlorinated biphenyls (PCBs) and 4,4′‐DDE in blood plasma from nestling eagles have declined over time for most subpopulations; however, they remain greater for breeding areas associated with the Great Lakes' food web. Sea eagles of the genus Haliaeetus are a good sentinel species to track trends in bioaccumulative compounds in aquatic systems. 相似文献
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Text search is a type of strategic reading that involves locating specific goal-relevant information. Previous research has indicated that college and high school students often exhibit inefficient or unsuccessful text-search performance. Consequently, the effects of 2 manipulations on text-search performance were investigated: (1) the presence of indexed terms in a text-search task and (2) the use of a planning prompt before beginning a task. 34 college students engaged in 6 text-search tasks. Half of these tasks contained terms that could be used in an index; half required that a search term be generated. Half of the subjects were randomly assigned to a prompt condition in which they were prompted to plan their search before beginning each task. The results indicated that a planning prompt raised the success level of search performance, as did the presence of terms that were searchable in the textbook's index. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Abstract: Environmental justice advocates have recently focused attention on cumulative exposure in minority neighborhoods due to multiple sources of pollution. This article uses U.S. EPA's National Air Toxics Assessment (NATA) for 1996 to examine environmental inequality in California, a state that has been a recent innovator in environmental justice policy. We first estimate potential lifetime cancer risks from mobile and stationary sources. We then consider the distribution of these risks using both simple comparisons and a multivariate model in which we control for income, land use, and other explanatory factors, as well as spatial correlation. We find large racial disparities in California's “riskscape” as well as inequalities by other factors and suggest several implications for environmental and land use policy. 相似文献
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Thai Binh Wan Rachel Seneviratne Aruna Rakotoarivelo Thierry 《Mobile Networks and Applications》2003,8(1):27-36
The high expectations and demand for users to access the Internet from anywhere at anytime has made user mobility an important part of the design and development of the next generation mobile communications and computing. Traditionally user mobility has been divided into two areas: Terminal Mobility and Personal Mobility. In recent years terminal mobility has focused on the movement of the terminal and developed extensions to IP protocols such as Mobile IP. In contrast, personal mobility has only received limited attention, and is somewhat lagging behind. This research has either focussed on personal mobility in communications or personalisation of operating environments. As a result, to date no framework for providing true personal mobility has emerged. In this paper, we introduce a new personal mobility framework called IPMoA (Integrated Personal Mobility Architecture), which integrates both aspects of personal mobility to provide a complete personal mobility solution, and illustrate the viability of this approach through a proof-of-concept implementation. 相似文献
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EJ Shpall SM Stemmer L Hami WA Franklin L Shaw HS Bonner SI Bearman WP Peters RC Bast W McCulloch 《Canadian Metallurgical Quarterly》1994,83(11):3132-3137
4-Hydroperoxycyclophosphamide (4-HC), a commonly used marrow-purging agent, is active against many tumors, but is also toxic to normal marrow progenitors. Amifostine (WR-2721) is a sulfhydryl compound with chemoprotectant activity. Preclinical studies using suspensions of bone marrow and breast cancer cells demonstrated that ex vivo treatment with amifostine followed by 4-HC resulted in protection of marrow progenitors, with no compromise in the antitumor effect of 4-HC. This fact stimulated the development of a clinical trial. Bone marrow was harvested from 15 poor-prognosis breast cancer patients and randomly assigned to ex vivo treatment with amifostine followed by 4-HC (amifostine + 4-HC), or treatment with 4-HC alone. High-dose chemotherapy was then administered followed by infusion of the purged autologous bone marrow support (ABMS). Leukocyte engraftment, defined as a white blood cell count > or = 1 x 10(9)/L, was achieved in an average of 26 days for patients whose marrow was purged with amifostine + 4-HC versus 36 days for patients whose marrow was purged with 4-HC alone (P = .032). The average number of platelet transfusions (12 v 29; P = .017) and days of antibiotic therapy (28 v 40; P = .012) were significantly less for patients whose marrow was exposed to amifostine + 4-HC, compared with 4-HC alone. Unpurged backup marrow fractions were infused into three patients whose marrow was purged with 4-HC alone, because of inadequate marrow recovery. None of the patients who received amifostine + 4-HC-purged marrow required a backup marrow fraction. Complete remissions were achieved in 83% of patients with measurable disease, with no difference between the two cohorts. Forty-three percent of patients remained alive and progression-free at a mean of 13 months posttransplant. There was no significant difference in the rate or pattern of relapse for patients whose marrow was purged with amifostine + 4-HC compared with those whose marrow was purged with 4-HC alone. Ex vivo treatment of marrow with amifostine significantly shortens the time to marrow recovery, thereby reducing the risk of myelosuppressive complications in breast cancer patients receiving high-dose chemotherapy and 4-HC-purged ABMS. Since supportive care requirements are also significantly decreased, amifostine may reduce the cost of such therapy. 相似文献
8.
Robin Daniel J.; Berthier Neil E.; Clifton Rachel K. 《Canadian Metallurgical Quarterly》1996,32(5):824
Infants were presented with a moving object under 2 lighting conditions to investigate the role of vision in early reaching. The motion of the target object also allowed for an analysis of the infants' ability to use a predictive style of reaching. Infants were tested twice, at 5 and 7.5 months of age, with a moving object in the light and the same object painted with luminescent paint in the dark. Infants successfully contacted the glowing object on about half of their attempts at both ages, although 7.5 month-olds reached more often. Infants also took into account the motion of the target object by aiming their reaches ahead of the object and by reaching with their contralateral hand. These results suggest that proprioceptive feedback and sight of the target allow for successful reaching with limited visual information, even in relatively complex reaching tasks. The infants' success also demonstrates their ability to adapt their movements and reaching strategy to the speed and trajectory of the target object in order to reach predictively. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Howard R. Moskowitz Michele Reisner Barbara Itty Rachel Katz Bert Krieger 《Food quality and preference》2006,17(7-8):536-551
Innovation is often left to insight and serendipity. A lot of what researchers call innovation is actually a process by which one can make the individual consumer or practitioner more ‘creative’. Although it is important to work with the creative individual in hopes of coming up with the better ‘idea’ and new product/service opportunity, an equally valid albeit novel and counterintuitive approach systematizes creativity in a ‘research-driven machine’. This paper presents an approach to the systematization, based upon the point of view that creativity and innovation comprise the recombination of components into new blends. Given this point of view, to then spur innovation requires a systematic database that the user can access, with tools to help manipulate that database. The paper shows how such a database can be constructed and then used to create a novel product. The approach provides a general framework for the sensory professional to become more involved in the early stages of product development, where the focus is on the conceptual aspects of food features rather than on their physical manifestations in actual products. 相似文献
10.
Computational Methods for Cardiac Electromechanics 总被引:3,自引:0,他引:3
Kerckhoffs R.C.P. Healy S.N. Usyk T.P. McCulloch A.D. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2006,94(4):769-783
Computational modeling provides a potentially powerful way to integrate structural properties measured in vitro to physiological functions measured in vivo. Focusing on the various scales (cell-tissue-organ-system), we give an overview of the importance and applications of numerical models of ventricular anatomy, electrophysiology, mechanics, and circulatory models. The integration of these models in one multiscale model of cardiac electromechanics is discussed in the light of applications to hypothesis generation, diagnosis, surgery(planning, training, and outcome of interventions), and therapies. Special attention is paid to practical use in terms of computational demand. Because of growing computer power and the development of efficient algorithms, we expect that real-time simulations with multiscale models of cardiac electromechanics become feasible in 2008 (despite the increasing complexity of models due to data accumulation on molecular and cellular mechanisms). 相似文献