全文获取类型
收费全文 | 4711篇 |
免费 | 215篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 67篇 |
综合类 | 2篇 |
化学工业 | 1306篇 |
金属工艺 | 157篇 |
机械仪表 | 92篇 |
建筑科学 | 120篇 |
矿业工程 | 11篇 |
能源动力 | 162篇 |
轻工业 | 583篇 |
水利工程 | 11篇 |
石油天然气 | 10篇 |
无线电 | 149篇 |
一般工业技术 | 719篇 |
冶金工业 | 1079篇 |
原子能技术 | 23篇 |
自动化技术 | 439篇 |
出版年
2023年 | 32篇 |
2022年 | 154篇 |
2021年 | 218篇 |
2020年 | 105篇 |
2019年 | 93篇 |
2018年 | 156篇 |
2017年 | 162篇 |
2016年 | 175篇 |
2015年 | 133篇 |
2014年 | 167篇 |
2013年 | 279篇 |
2012年 | 189篇 |
2011年 | 254篇 |
2010年 | 157篇 |
2009年 | 153篇 |
2008年 | 150篇 |
2007年 | 145篇 |
2006年 | 99篇 |
2005年 | 81篇 |
2004年 | 80篇 |
2003年 | 66篇 |
2002年 | 63篇 |
2001年 | 36篇 |
2000年 | 32篇 |
1999年 | 34篇 |
1998年 | 191篇 |
1997年 | 213篇 |
1996年 | 147篇 |
1995年 | 112篇 |
1994年 | 57篇 |
1993年 | 72篇 |
1992年 | 20篇 |
1991年 | 15篇 |
1990年 | 21篇 |
1989年 | 19篇 |
1988年 | 23篇 |
1987年 | 30篇 |
1986年 | 20篇 |
1985年 | 32篇 |
1984年 | 37篇 |
1983年 | 29篇 |
1982年 | 50篇 |
1981年 | 54篇 |
1980年 | 61篇 |
1979年 | 32篇 |
1978年 | 39篇 |
1977年 | 122篇 |
1976年 | 238篇 |
1975年 | 17篇 |
1973年 | 13篇 |
排序方式: 共有4930条查询结果,搜索用时 15 毫秒
71.
Artur Bekaa Wodzimierz Potek Dorota Siwicka-Gieroba Joanna Soek-Pastuszka Romuald Bohatyrewicz Jowita Biernawska Katarzyna Kotfis Magdalena Bielacz Andrzej Jaroszyski Wojciech Dabrowski 《International journal of molecular sciences》2022,23(13)
Brain injury, especially traumatic brain injury (TBI), may induce severe dysfunction of extracerebral organs. Cardiac dysfunction associated with TBI is common and well known as the brain–heart crosstalk, which broadly refers to different cardiac disorders such as cardiac arrhythmias, ischemia, hemodynamic insufficiency, and sudden cardiac death, which corresponds to acute disorders of brain function. TBI-related cardiac dysfunction can both worsen the brain damage and increase the risk of death. TBI-related cardiac disorders have been mainly treated symptomatically. However, the analysis of pathomechanisms of TBI-related cardiac dysfunction has highlighted an important role of melatonin in the prevention and treatment of such disorders. Melatonin is a neurohormone released by the pineal gland. It plays a crucial role in the coordination of the circadian rhythm. Additionally, melatonin possesses strong anti-inflammatory, antioxidative, and antiapoptotic properties and can modulate sympathetic and parasympathetic activities. Melatonin has a protective effect not only on the brain, by attenuating its injury, but on extracranial organs, including the heart. The aim of this study was to analyze the molecular activity of melatonin in terms of TBI-related cardiac disorders. Our article describes the benefits resulting from using melatonin as an adjuvant in protection and treatment of brain injury-induced cardiac dysfunction. 相似文献
72.
Verification of identity based on the analysis of dynamic signatures is an important problem of biometrics. The effectiveness of the verification significantly increases when the dynamic characteristics of signature (e.g. velocity of the pen) are considered. These characteristics are individual for each user and difficult to imitate. The effectiveness of the verification can be further improved by using partitioning. In this paper we propose a new method which uses partitioning. In our method partitions represent areas of high and low speed of signature and high and low pen?s pressure. All selected partitions are used by our algorithm, but more important in the classification process are these partitions, in which the signatures of the user acquired during training phase are more stable. Moreover, final classification is interpretable. In this paper we present the simulation results of the proposed method for the two databases: SVC2004 and BioSecure Database. 相似文献
73.
Veronika Bilanovi
ov Nikola Rýdza Lilla Koczka Martin Hess Elena Feraru Jií Friml Tomasz Nodzyski 《International journal of molecular sciences》2022,23(11)
Much of plant development depends on cell-to-cell redistribution of the plant hormone auxin, which is facilitated by the plasma membrane (PM) localized PIN FORMED (PIN) proteins. Auxin export activity, developmental roles, subcellular trafficking, and polarity of PINs have been well studied, but their structure remains elusive besides a rough outline that they contain two groups of 5 alpha-helices connected by a large hydrophilic loop (HL). Here, we focus on the PIN1 HL as we could produce it in sufficient quantities for biochemical investigations to provide insights into its secondary structure. Circular dichroism (CD) studies revealed its nature as an intrinsically disordered protein (IDP), manifested by the increase of structure content upon thermal melting. Consistent with IDPs serving as interaction platforms, PIN1 loops homodimerize. PIN1 HL cytoplasmic overexpression in Arabidopsis disrupts early endocytic trafficking of PIN1 and PIN2 and causes defects in the cotyledon vasculature formation. In summary, we demonstrate that PIN1 HL has an intrinsically disordered nature, which must be considered to gain further structural insights. Some secondary structures may form transiently during pairing with known and yet-to-be-discovered interactors. 相似文献
74.
Karolina Maciejewska Kamila Czarnecka Pawe Krcisz Dorota Niedziaek Grzegorz Wieczorek Robert Skibiski Pawe Szymaski 《International journal of molecular sciences》2022,23(11)
A series of new cyclopentaquinoline derivatives with 9-acridinecarboxylic acid and a different alkyl chain length were synthesized, and their ability to inhibit cholinesterases was evaluated. All designed compounds, except derivative 3f, exhibited a selectivity for butyrylcholinesterase (BuChE) with IC50 values ranging from 103 to 539 nM. The 3b derivative revealed the highest inhibitory activity towards BuChE (IC50 = 103.73 nM) and a suitable activity against AChE (IC50 = 272.33 nM). The 3f derivative was the most active compound to AChE (IC50 = 113.34 nM) with satisfactory activity towards BuChE (IC50 = 203.52 nM). The potential hepatotoxic effect was evaluated for both 3b and 3f compounds. The 3b and 3f potential antioxidant activity was measured using the ORAC-FL method. The 3b and 3f derivatives revealed a significantly higher antioxidant potency, respectively 35 and 25 higher than tacrine. Theoretical, physicochemical, and pharmacokinetic properties were calculated using ACD Labs Percepta software. Molecular modeling and kinetic study were used to reveal the mechanism of cholinesterase inhibition in the most potent compounds: 3b and 3f. 相似文献
75.
Sebastian Szewczyk Alice Goyal Mateusz Abram Gotard Burdziski Joanna Kargul Krzysztof Gibasiewicz 《International journal of molecular sciences》2022,23(9)
A film of ~40 layers of partially oriented photosystem I (PSI) complexes isolated from the red alga Cyanidioschyzon merolae formed on the conducting glass through electrodeposition was investigated by time-resolved absorption spectroscopy and chronoamperometry. The experiments were performed at a range of electric potentials applied to the film and at different compositions of electrolyte solution being in contact with the film. The amount of immobilized proteins supporting light-induced charge separation (active PSI) ranged from ~10%, in the absence of any reducing agents (redox compounds or low potential), to ~20% when ascorbate and 2,6-dichlorophenolindophenol were added, and to ~35% when the high negative potential was additionally applied. The origin of the large fraction of permanently inactive PSI (65–90%) was unclear. Both reducing agents increased the subpopulation of active PSI complexes, with the neutral P700 primary electron donor, by reducing significant fractions of the photo-oxidized P700 species. The efficiencies of light-induced charge separation in the PSI film (10–35%) did not translate into an equally effective generation of photocurrent, whose internal quantum efficiency reached the maximal value of 0.47% at the lowest potentials. This mismatch indicates that the vast majority of the charge-separated states in multilayered PSI complexes underwent charge recombination. 相似文献
76.
We present an overview of some recent developments in the area of mathematical modeling of maintenance decisions for multi-unit systems. The emphasis is on three main groups of multicomponent maintenance optimization models: the block replacement models, group maintenance models, and opportunistic maintenance models. Moreover, an example of a two-unit system maintenance process is provided in order to compare various maintenance policies. 相似文献
77.
Robust ordinal regression in preference learning and ranking 总被引:1,自引:0,他引:1
Salvatore Corrente Salvatore Greco Miłosz Kadziński Roman Słowiński 《Machine Learning》2013,93(2-3):381-422
Multiple Criteria Decision Aiding (MCDA) offers a diversity of approaches designed for providing the decision maker (DM) with a recommendation concerning a set of alternatives (items, actions) evaluated from multiple points of view, called criteria. This paper aims at drawing attention of the Machine Learning (ML) community upon recent advances in a representative MCDA methodology, called Robust Ordinal Regression (ROR). ROR learns by examples in order to rank a set of alternatives, thus considering a similar problem as Preference Learning (ML-PL) does. However, ROR implements the interactive preference construction paradigm, which should be perceived as a mutual learning of the model and the DM. The paper clarifies the specific interpretation of the concept of preference learning adopted in ROR and MCDA, comparing it to the usual concept of preference learning considered within ML. This comparison concerns a structure of the considered problem, types of admitted preference information, a character of the employed preference models, ways of exploiting them, and techniques to arrive at a final ranking. 相似文献
78.
Mikołaj Bojańczyk 《Theory of Computing Systems》2013,53(2):194-222
We develop an algebraic theory for languages of data words. We prove that, under certain conditions, a language of data words is definable in first-order logic if and only if its syntactic monoid is aperiodic. 相似文献
79.
The influence of thermal treatment, pickling and fermentation on the content of glucobrassicin and its selected breakdown products in broccoli and cauliflower was investigated. The highest content of glucobrassicin and the lowest content of its breakdown products were found in vegetables which underwent thermal treatment such as boiling and steam cooking. The lowest content of glucobrassicin and the highest content of its breakdown products were present in raw, pickled and fermented vegetables in which the myrosinase remained active. Ascrobigen was the major glucobrassicin breakdown product and its content was negatively correlated with glucobrassicin content in broccoli and cauliflower. After heating of vegetables in 60 °C for 20 min (causing thermal deactivation of epithiospecific protein) no presence of indole-3-acetonitrile was found. 相似文献
80.
This paper presents methods for improving the quality of IR images that significantly facilitate the detection of physical and structural non-uniformities in layered objects. The methods are based on wavelets transformations. Both, discrete and continuous wavelet transforms were used. The space-scale representation of thermal image are used for the detection thermal non-uniformities in the objects examined. Examples of recorded and improved images are presented in this paper. 相似文献