全文获取类型
收费全文 | 357篇 |
免费 | 29篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 150篇 |
金属工艺 | 5篇 |
机械仪表 | 11篇 |
建筑科学 | 20篇 |
矿业工程 | 1篇 |
能源动力 | 4篇 |
轻工业 | 73篇 |
水利工程 | 4篇 |
无线电 | 10篇 |
一般工业技术 | 57篇 |
冶金工业 | 23篇 |
原子能技术 | 2篇 |
自动化技术 | 23篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 22篇 |
2021年 | 36篇 |
2020年 | 19篇 |
2019年 | 10篇 |
2018年 | 12篇 |
2017年 | 23篇 |
2016年 | 16篇 |
2015年 | 16篇 |
2014年 | 20篇 |
2013年 | 23篇 |
2012年 | 19篇 |
2011年 | 27篇 |
2010年 | 19篇 |
2009年 | 15篇 |
2008年 | 17篇 |
2007年 | 17篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有386条查询结果,搜索用时 15 毫秒
51.
Michaela Titz Karl-Heinz Kettl Khurram Shahzad Martin Koller Hans Schnitzer Michael Narodoslawsky 《Clean Technologies and Environmental Policy》2012,14(3):495-503
Conventional polymers are made of crude oil components through chemical polymerization. The aim of the project ANIMPOL is to produce biopolymers by converting lipids into polyhydroxyalkanoates (PHA) in a novel process scheme to reduce dependence on crude oil and decrease greenhouse gas emissions. PHA constitutes a group of biobased and biodegradable polyesters that may substitute fossil-based polymers in a wide range of applications. Waste streams from slaughtering cattle are used as substrate material. Lipids from rendering are used in this process scheme for biodiesel production. Slaughtering waste streams may also be hydrolyzed to achieve higher lipid yield. Biodiesel then is separated into a high- and low-quality fraction. High-quality biodiesel meets requirements for sale as fuel and low quality is used for PHA production as carbon source. Selected offal material is used for acid hydrolysis and serves as a source of organic nitrogen as well as carbon source for PHA-free biomass with high production rate in fermentation process. Nitrogen is a limiting factor to control PHA production during the fermentation process. It is available for bacterial growth from hydrolyzed waste streams as well as added separately as NH4OH solution. Selected microbial strains are used to produce PHA from this substrate. The focus of the paper is about an overview of the whole process with the main focus on hydrolysis, to look for the possibility of using offal hydrolysis as an organic nitrogen substitute. The process design is optimized by minimizing waste streams and energy losses through cleaner production. Ecological evaluation of the process design will be done through footprint calculation according to Sustainable Process Index methodology. 相似文献
52.
The Formation of Calcified Nanospherites during Micropetrosis Represents a Unique Mineralization Mechanism in Aged Human Bone 下载免费PDF全文
Petar Milovanovic Elizabeth A. Zimmermann Annika vom Scheidt Björn Hoffmann George Sarau Timur Yorgan Michaela Schweizer Michael Amling Silke Christiansen Björn Busse 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(3)
Osteocytes—the central regulators of bone remodeling—are enclosed in a network of microcavities (lacunae) and nanocanals (canaliculi) pervading the mineralized bone. In a hitherto obscure process related to aging and disease, local plugs in the lacuno‐canalicular network disrupt cellular communication and impede bone homeostasis. By utilizing a suite of high‐resolution imaging and physics‐based techniques, it is shown here that the local plugs develop by accumulation and fusion of calcified nanospherites in lacunae and canaliculi (micropetrosis). Two distinctive nanospherites phenotypes are found to originate from different osteocytic elements. A substantial deviation in the spherites' composition in comparison to mineralized bone further suggests a mineralization process unlike regular bone mineralization. Clearly, mineralization of osteocyte lacunae qualifies as a strong marker for degrading bone material quality in skeletal aging. The understanding of micropetrosis may guide future therapeutics toward preserving osteocyte viability to maintain mechanical competence and fracture resistance of bone in elderly individuals. 相似文献
53.
This paper explores the role of distant knowledge links and policy actions for the development of biotechnology clusters. It seeks to challenge the prevailing view that the birth and early development of high technology industries are always spontaneous phenomena which are mainly based on local knowledge. Departing from the theoretical concept of regional innovation systems (RIS), a distinction between “RIS with strong potentials for high technology industries” and “RIS with weak potentials for high technology industries” will be drawn. It will be argued that in the latter case the development of biotechnology clusters is more dependent on distant knowledge sources and proactive policy efforts to create a favourable environment for high technology activities. Furthermore, it will be shown that a far-reaching transformation of the regional innovation system is crucial for catching-up processes of regions which are latecomers in high technology sectors such as biotechnology. 相似文献
54.
Phytoestrogens are a group of polyphenolic plant metabolites that can induce biological responses. Their bioactivity is based on their similarity to 17beta-estradiol and their ability to bind to the beta-estrogen receptor. Although epidemiological data are inconclusive, phytoestrogens are considered to be beneficial for a variety of conditions, for example, hormone-related cancers like breast and prostate cancer. To investigate the biological effects of these compounds and to assess the exposure of larger cohorts or the general public, reliable data on the phytoestrogen content of food is necessary. Previously, food analysis for phytoestrogens was performed using either HPLC-UV or GC/MS. Here, we describe the development of the first generic method for the analysis of phytoestrogens in food, using automated solid-phase extraction and liquid chromatography-tandem mass spectrometry. The presented method shows a good reproducibility and can be easily adapted to other phytoestrogens if required. 相似文献
55.
Kleinspehn-Ammerlahn Anna; Riediger Michaela; Schmiedek Florian; von Oertzen Timo; Li Shu-Chen; Lindenberger Ulman 《Canadian Metallurgical Quarterly》2011,47(3):632
Many social interactions require the synchronization—be it automatically or intentionally—of one's own behavior with that of others. Using a dyadic drumming paradigm, the authors delineate lifespan differences in interpersonal action synchronization (IAS). Younger children, older children, younger adults, and older adults in same- and mixed-age dyads were instructed to drum in synchrony with their interaction partner at a constant, self-chosen tempo. Adult-only dyads showed the highest and children-only the lowest levels of IAS accuracy. It is important to note that children improved reliably in IAS accuracy when paired with older partners. The observed age-related differences in IAS accuracy remained reliable after statistically controlling for individual differences in the ability to synchronize to a metronome and for between-dyad differences in tempo. The authors conclude that IAS improves from middle childhood to adulthood and that adult interaction partners may facilitate its development. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
56.
57.
Rösch P Harz M Peschke KD Ronneberger O Burkhardt H Schüle A Schmauz G Lankers M Hofer S Thiele H Motzkus HW Popp J 《Analytical chemistry》2006,78(7):2163-2170
Fast analysis of bioaerosols in clean room environments is necessary in order to prevent contamination of pharmaceutical products, minimize machine downtimes, or both. The detection and identification of microbes will be carried out in several steps: After impaction of the aerosol on a surface, the particles are presorted with glancing light illumination and fluorescence imaging in order to distinguish between abiotic and biotic particles. Since only the biotic particles are of interest, the analysis time can be minimized due to reduction of the data set. The biotic particles are then analyzed further with Raman spectroscopy and identified with a support vector machine. 相似文献
58.
The advantages of mathematical simulations of the process of cured hide desalination are presented. Full three‐dimensional model is presented and then its one‐dimensional and a two‐dimensional special cases are considered and compared. In the case of one‐dimensional approximation, the solution can be obtained in an analytic form, while for the two‐dimensional case only numerical solution is available. A possible occurrence of a concentration shock is modelled, and a method of its prevention is proposed to reduce losses in the hide substance. The predictions of the mathematical model are then compared with experimental data and found to be in good agreement. 相似文献
59.
Tobias?MettlerEmail authorView authors OrcID profile Michaela?Sprenger Robert?Winter 《欧洲信息系统杂志》2017,26(5):451-468
Changing demands in society and the limited capabilities of health systems have paved the way for robots to move out of industrial contexts and enter more human-centered environments such as health care. We explore the shared beliefs and concerns of health workers on the introduction of autonomously operating service robots in hospitals or professional care facilities. By means of Q-methodology, a mixed research approach specifically designed for studying subjective thought patterns, we identify five potential end-user niches, each of which perceives different affordances and outcomes from using service robots in their working environment. Our findings allow for better understanding resistance and susceptibility of different users in a hospital and encourage managerial awareness of varying demands, needs, and surrounding conditions that a service robot must contend with. We also discuss general insights into presenting the Q-methodology results and how an affordance-based view could inform the adoption, appropriation, and adaptation of emerging technologies. 相似文献
60.
Matthew R Hartings Noah Benjamin Floriene Briere Maria Briscione Omar Choudary Tamra L Fisher Laura Flynn Elizabeth Ghias Michaela Harper Nader Khamis Catherine Koenigsknecht Klare Lazor Steven Moss Elaine Robbins Susan Schultz Samiye Yaman Luke M Haverhals Paul C Trulove Hugh C De Long Abigail E Miller Douglas M Fox 《Science and Technology of Advanced Materials》2013,14(6)
AbstractA technique was developed for preparing a novel material that consists of gold nanoparticles trapped within a fiber of unfolded proteins. These fibers are made in an aqueous solution that contains HAuCl4 and the protein, bovine serum albumin (BSA). By changing the ratio of gold to BSA in solution, two different types of outcomes are observed. At lower gold to BSA ratios (30–120), a purple solution results after heating the mixture at 80 °C for 4 h. At higher gold to BSA ratios (130–170), a clear solution containing purple fibers results after heating the mixture at 80 °C for 4 h. UV–Vis spectroscopy and light scattering techniques show growth in nanocolloid size as gold to BSA ratio rises above 100. Data indicate that, for the higher gold to BSA ratios, the gold is sequestered within the solid material. The material mass, visible by eye, appears to be an aggregation of smaller individual fibers. Scanning electron microscopy and transmission electron microscopy indicate that these fibers are primarily one-dimensional aggregates, which can display some branching, and can be as narrow as 400 nm in size. The likely mechanism for the synthesis of the novel material is discussed. 相似文献