全文获取类型
收费全文 | 3744篇 |
免费 | 186篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 3933篇 |
出版年
2024年 | 10篇 |
2023年 | 53篇 |
2022年 | 122篇 |
2021年 | 173篇 |
2020年 | 89篇 |
2019年 | 87篇 |
2018年 | 125篇 |
2017年 | 120篇 |
2016年 | 127篇 |
2015年 | 108篇 |
2014年 | 167篇 |
2013年 | 260篇 |
2012年 | 227篇 |
2011年 | 288篇 |
2010年 | 207篇 |
2009年 | 169篇 |
2008年 | 174篇 |
2007年 | 185篇 |
2006年 | 120篇 |
2005年 | 106篇 |
2004年 | 105篇 |
2003年 | 94篇 |
2002年 | 81篇 |
2001年 | 45篇 |
2000年 | 44篇 |
1999年 | 37篇 |
1998年 | 79篇 |
1997年 | 72篇 |
1996年 | 42篇 |
1995年 | 40篇 |
1994年 | 30篇 |
1993年 | 26篇 |
1992年 | 25篇 |
1991年 | 17篇 |
1990年 | 31篇 |
1989年 | 19篇 |
1988年 | 14篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 18篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1977年 | 9篇 |
1976年 | 25篇 |
1975年 | 8篇 |
1974年 | 10篇 |
排序方式: 共有3933条查询结果,搜索用时 0 毫秒
71.
L. Czarnecki 《Electrical Engineering (Archiv fur Elektrotechnik)》2003,85(1):21-28
The comparison of the instantaneous reactive power (IRP) p-q theory with the theory of the current's physical components (CPC) presented in this paper provides the relationship between powers in both theories applied to three-phase, three-wire circuits with sinusoidal voltages and currents. It shows that results of the instantaneous reactive power p-q theory are inconsistent with power phenomena in such circuits. Namely, the IRP q may occur in circuits with linear, purely resistive loads thus, with zero reactive power, Q, and the instantaneous active power p may occur in circuits with purely reactive loads, thus, with zero active power, P. Consequently, the IRP p-q theory fails to identify the power properties of three-phase circuits with unbalanced loads. Moreover, in spite of sinusoidal supply and the lack of distortion, the IRP p-q theory suggests that the active and reactive currents contain a third-order harmonic. Also the IRP p-q theory is not capable of providing information on power properties of the load instantaneously. 相似文献
72.
This paper presents results of investigation of the stress sensitivity of the fluxgate sensor with amorphous alloy (CoFe)89(MnMoSiB)11 (Vitrovac 6150F) ring core. Stress was applied in two directions: perpendicularly to the flux density in the ring core or in the direction of diameter of the ring. The influence of mechanical stress from the external forces on magnetic properties of this ring core was measured. Then results of this testing were used in computer simulation of the influence of the stress on the output signal of the fluxgate sensor. 相似文献
73.
The objective of this research is to develop a framework named Wise-ShopFloor and the enabling technologies for collaborative
manufacturing in a decentralized environment. Particularly, this paper presents our latest development on Web-based and sensor-driven
remote machining. Once a product design is given, its process plan and NC codes are generated by using a distributed process
planning (DPP) system. The NC codes are then used for remote machining via a standard Web browser and a Java GUI interface
running inside the browser. In this paper, the focus is given to the concept, architecture and a prototype implementation
of the enabling technology. A case study of a test part machining on a 5-axis milling machine is also completed for testing
and validation. It is expected that the developed technology can be applied to design verification via remote machining as
well as real part production in a distributed manufacturing environment. 相似文献
74.
75.
Franjo Banovic Sandrin Schulze Mobarak Abu Mraheil Torsten Hain Trinad Chakraborty Vronique Orian-Rousseau Selina Moroniak Christel Weiss Hiroshi Ishikawa Horst Schroten Rüdiger Adam Christian Schwerk 《International journal of molecular sciences》2022,23(21)
The human central nervous system (CNS) is separated from the blood by distinct cellular barriers, including the blood–brain barrier (BBB) and the blood–cerebrospinal fluid (CFS) barrier (BCSFB). Whereas at the center of the BBB are the endothelial cells of the brain capillaries, the BCSFB is formed by the epithelium of the choroid plexus. Invasion of cells of either the BBB or the BCSFB is a potential first step during CNS entry by the Gram-positive bacterium Listeria monocytogenes (Lm). Lm possesses several virulence factors mediating host cell entry, such as the internalin protein family—including internalin (InlA), which binds E-cadherin (Ecad) on the surface of target cells, and internalin B (InlB)—interacting with the host cell receptor tyrosine kinase Met. A further family member is internalin (InlF), which targets the intermediate filament protein vimentin. Whereas InlF has been shown to play a role during brain invasion at the BBB, its function during infection at the BCSFB is not known. We use human brain microvascular endothelial cells (HBMEC) and human choroid plexus epithelial papilloma (HIBCPP) cells to investigate the roles of InlF and vimentin during CNS invasion by Lm. Whereas HBMEC present intracellular and surface vimentin (besides Met), HIBCPP cells do not express vimentin (except Met and Ecad). Treatment with the surface vimentin modulator withaferin A (WitA) inhibited invasion of Lm into HBMEC, but not HIBCPP cells. Invasion of Lm into HBMEC and HIBCPP cells is, however, independent of InlF, since a deletion mutant of Lm lacking InlF did not display reduced invasion rates. 相似文献
76.
77.
Grzegorz Krasowski Pawe Migda Marta Woroszyo Karol Fijakowski Grzegorz Chodaczek Joanna Czajkowska Bartomiej Dudek Joanna Nowicka Monika Oleksy-Wawrzyniak Bartomiej Kwiek Justyna Paleczny Malwina Broyna Adam Junka 《International journal of molecular sciences》2022,23(21)
Staphylococcal biofilms are major causative factors of non-healing wound infections. Their treatment algorithms recommend the use of locally applied antiseptic agents to counteract the spread of infection. The efficacy of antiseptics against biofilm is assessed in vitro by a set of standard quantitative and semi-quantitative methods. The development of software for image processing additionally allowed for the obtainment of quantitative data from microscopic images of biofilm dyed with propidium iodine and SYTO-9 reagents, differentiating dead cells from live ones. In this work, the method of assessment of the impact of antiseptic agents on staphylococcal biofilm in vitro, based on biofilms’ processed images, was proposed and scrutinized with regard to clinically relevant antiseptics, polyhexanide, povidone–iodine and hypochlorite. The standard quantitative culturing method was applied to validate the obtained data from processed images. The results indicated significantly higher activity of polyhexanide and povidone–iodine than hypochlorite against staphylococcal biofilm. Taking into account the fact that in vitro results of the efficacy of antiseptic agents against staphylococcal biofilm are frequently applied to back up their use in hospitals and ambulatory units, our work should be considered an important tool; providing reliable, quantitative data in this regard. 相似文献
78.
Mariana Toledo Gonalves Moreira Patricia Ribeiro Pereira Adriano Aquino Carlos Adam Conte-Junior Vania Margaret Flosi Paschoalin 《International journal of molecular sciences》2022,23(22)
Aldehydes, particularly acetaldehyde, are carcinogenic molecules and their concentrations in foodstuffs should be controlled to avoid upper aerodigestive tract (UADT) and liver cancers. Highly reactive, acetaldehyde forms DNA and protein adducts, impairing physiological functions and leading to the development of pathological conditions. The consumption of aged beer, outside of the ethanol metabolism, exposes habitual drinkers to this carcinogen, whose concentrations can be over-increased due to post-brewing chemical and biochemical reactions. Storage-related changes are a challenge faced by the brewing industry, impacting volatile compound formation and triggering flavor instability. Aldehydes are among the volatile compounds formed during beer aging, recognized as off-flavor compounds. To track and understand aldehyde formation through multiple pathways during beer storage, consequent changes in flavor but particularly quality losses and harmful compound formation, this systematic review reunited data on volatile compound profiles through gas chromatography analyses from 2011 to 2021. Conditions to avoid flavor instability and successful methods for reducing beer staling, and consequent acetaldehyde accumulation, were raised by exploring the dynamic conversion between free and bound-state aldehydes. Future research should focus on implementing sensory analyses to investigate whether adding aldehyde-binding agents, e.g., cysteine and bisulfite, would contribute to consumer acceptance, restore beer flavor, and minimize acetaldehyde-related health damage. 相似文献
79.
80.
Beata Podgrska Marta Wielogrska-Partyka Joanna Godzie Julia Siemiska Micha Ciborowski Magorzata Szelachowska Adam Krtowski Katarzyna Siewko 《International journal of molecular sciences》2022,23(18)
The pathogenesis of the disorders of calcium metabolism is not fully understood. This review discusses the studies in which metabolomics was applied in this area. Indeed, metabolomics could play an essential role in discovering biomarkers and elucidating pathological mechanisms. Despite the limited bibliography, the present review highlights the potential of metabolomics in identifying the biomarkers of some of the most common endocrine disorders, such as primary hyperparathyroidism (PHPT), secondary hyperparathyroidism (SHPT), calcium deficiency, osteoporosis and vitamin D supplementation. Metabolites related to above-mentioned diseorders were grouped into specific classes and mapped into metabolic pathways. Furthermore, disturbed metabolic pathways can open up new directions for the in-depth exploration of the basic mechanisms of these diseases at the molecular level. 相似文献