全文获取类型
收费全文 | 5101篇 |
免费 | 170篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 52篇 |
综合类 | 1篇 |
化学工业 | 951篇 |
金属工艺 | 85篇 |
机械仪表 | 89篇 |
建筑科学 | 303篇 |
矿业工程 | 18篇 |
能源动力 | 133篇 |
轻工业 | 460篇 |
水利工程 | 43篇 |
石油天然气 | 38篇 |
武器工业 | 1篇 |
无线电 | 278篇 |
一般工业技术 | 861篇 |
冶金工业 | 1006篇 |
原子能技术 | 21篇 |
自动化技术 | 942篇 |
出版年
2023年 | 32篇 |
2022年 | 40篇 |
2021年 | 84篇 |
2020年 | 74篇 |
2019年 | 63篇 |
2018年 | 91篇 |
2017年 | 76篇 |
2016年 | 127篇 |
2015年 | 90篇 |
2014年 | 161篇 |
2013年 | 352篇 |
2012年 | 242篇 |
2011年 | 320篇 |
2010年 | 223篇 |
2009年 | 190篇 |
2008年 | 254篇 |
2007年 | 233篇 |
2006年 | 192篇 |
2005年 | 193篇 |
2004年 | 138篇 |
2003年 | 130篇 |
2002年 | 132篇 |
2001年 | 82篇 |
2000年 | 72篇 |
1999年 | 81篇 |
1998年 | 105篇 |
1997年 | 113篇 |
1996年 | 76篇 |
1995年 | 74篇 |
1994年 | 60篇 |
1993年 | 72篇 |
1992年 | 78篇 |
1991年 | 45篇 |
1990年 | 49篇 |
1989年 | 56篇 |
1988年 | 50篇 |
1987年 | 49篇 |
1986年 | 56篇 |
1985年 | 71篇 |
1984年 | 58篇 |
1983年 | 73篇 |
1982年 | 48篇 |
1981年 | 36篇 |
1980年 | 45篇 |
1979年 | 61篇 |
1978年 | 46篇 |
1977年 | 45篇 |
1976年 | 37篇 |
1975年 | 38篇 |
1973年 | 26篇 |
排序方式: 共有5282条查询结果,搜索用时 15 毫秒
11.
Effective on-line algorithms for reliable due date quotation and large-scale scheduling 总被引:1,自引:0,他引:1
We consider the sequencing of a series of jobs that arrive at a single processor over time. At each job’s arrival time, a
due date must be quoted for the job, and the job must complete processing before its quoted due date. The objective is to
minimize the sum (or average) of quoted due dates, or equivalently, the average quoted lead time. In this paper, we propose
on-line heuristics for this problem and characterize the conditions under which these heuristics are asymptotically optimal.
Computational testing further demonstrates the relative effectiveness of these heuristics under various conditions.
Both authors made equal contributions to this paper and are listed in alphabetical order. 相似文献
12.
A dichoptic masking procedure was used to test whether the mask-dependent cuing effects found in luminance detection by P. L. Smith (2000a) were due to integration masking or interruption masking. Attentional cuing enhanced detection sensitivity (d') when stimuli were backwardly masked with either dichoptic or monoptic masks, whereas no cuing effect was found with unmasked stimuli, implying the mask dependencies were due to interruption of stimulus processing in visual cortex by the mask. The effect is predicted by a gated diffusion process model in which masks interrupt stimulus processing and attention controls the flow of information to a sequential-sampling decision mechanism. The model correctly predicts different patterns of performance for detection and discrimination and cuing effects in simple reaction time. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
13.
Intramyocardial Inflammation after COVID-19 Vaccination: An Endomyocardial Biopsy-Proven Case Series
Christian Baumeier Ganna Aleshcheva Dominik Harms Ulrich Gross Christian Hamm Birgit Assmus Ralf Westenfeld Malte Kelm Spyros Rammos Philip Wenzel Thomas Münzel Albrecht Elssser Mudather Gailani Christian Perings Alae Bourakkadi Markus Flesch Tibor Kempf Johann Bauersachs Felicitas Escher Heinz-Peter Schultheiss 《International journal of molecular sciences》2022,23(13)
Myocarditis in response to COVID-19 vaccination has been reported since early 2021. In particular, young male individuals have been identified to exhibit an increased risk of myocardial inflammation following the administration of mRNA-based vaccines. Even though the first epidemiological analyses and numerous case reports investigated potential relationships, endomyocardial biopsy (EMB)-proven cases are limited. Here, we present a comprehensive histopathological analysis of EMBs from 15 patients with reduced ejection fraction (LVEF = 30 (14–39)%) and the clinical suspicion of myocarditis following vaccination with Comirnaty® (Pfizer-BioNTech) (n = 11), Vaxzevria® (AstraZenica) (n = 2) and Janssen® (Johnson & Johnson) (n = 2). Immunohistochemical EMB analyses reveal myocardial inflammation in 14 of 15 patients, with the histopathological diagnosis of active myocarditis according the Dallas criteria (n = 2), severe giant cell myocarditis (n = 2) and inflammatory cardiomyopathy (n = 10). Importantly, infectious causes have been excluded in all patients. The SARS-CoV-2 spike protein has been detected sparsely on cardiomyocytes of nine patients, and differential analysis of inflammatory markers such as CD4+ and CD8+ T cells suggests that the inflammatory response triggered by the vaccine may be of autoimmunological origin. Although a definitive causal relationship between COVID-19 vaccination and the occurrence of myocardial inflammation cannot be demonstrated in this study, data suggest a temporal connection. The expression of SARS-CoV-2 spike protein within the heart and the dominance of CD4+ lymphocytic infiltrates indicate an autoimmunological response to the vaccination. 相似文献
14.
Crivelli S Byrd R Eskow E Schnabe R Yu R Philip TM Head-Gordon T 《Computers & chemistry》2000,24(3-4):489-497
We present a global optimization strategy that incorporates predicted restraints in both a local optimization context and as directives for global optimization approaches, to predict protein tertiary structure for alpha-helical proteins. Specifically, neural networks are used to predict the secondary structure of a protein, restraints are defined as manifestations of the network with a predicted secondary structure and the secondary structure is formed using local minimizations on a protein energy surface, in the presence of the restraints. Those residues predicted to be coil, by the network, define a conformational sub-space that is subject to optimization using a global approach known as stochastic perturbation that has been found to be effective for Lennard-Jones clusters and homo-polypeptides. Our energy surface is an all-atom 'gas phase' molecular mechanics force field, that is combined with a new solvation energy function that penalizes hydrophobic group exposure. This energy function gives the crystal structure of four different alpha-helical proteins as the lowest energy structure relative to other conformations, with correct secondary structure but incorrect tertiary structure. We demonstrate this global optimization strategy by determining the tertiary structure of the A-chain of the alpha-helical protein, uteroglobin and of a four-helix bundle, DNA binding protein. 相似文献
15.
Philip C. Trackman Yaser Peymanfar Sayon Roy 《International journal of molecular sciences》2022,23(9)
Lysyl oxidases are multifunctional proteins derived from five lysyl oxidase paralogues (LOX) and lysyl oxidase-like 1 through lysyl oxidase-like 4 (LOXL1–LOXL4). All participate in the biosynthesis of and maturation of connective tissues by catalyzing the oxidative deamination of lysine residues in collagens and elastin, which ultimately results in the development of cross-links required to function. In addition, the five LOX genes have been linked to fibrosis and cancer when overexpressed, while tumor suppression by the propeptide derived from pro-LOX has been documented. Similarly, in diabetic retinopathy, LOX overexpression, activity, and elevated LOX propeptide have been documented. The proteolytic processing of pro-forms of the respective proteins is beginning to draw attention as the resultant peptides appear to exhibit their own biological activities. In this review we focus on the LOX paralogue, and what is known regarding its extracellular biosynthetic processing and the still incomplete knowledge regarding the activities and mechanisms of the released lysyl oxidase propeptide (LOX-PP). In addition, a summary of the roles of both LOX and LOX-PP in diabetic retinopathy, and brief mentions of the roles for LOX and closely related LOXL1 in glaucoma, and keratoconus, respectively, are included. 相似文献
16.
17.
Luna Karlos; Higham Philip A.; Martín-Luengo Beatriz 《Canadian Metallurgical Quarterly》2011,17(2):148
We report two experiments that investigated the regulation of memory accuracy with a new regulatory mechanism: the plurality option. This mechanism is closely related to the grain-size option but involves control over the number of alternatives contained in an answer rather than the quantitative boundaries of a single answer. Participants were presented with a slideshow depicting a robbery (Experiment 1) or a murder (Experiment 2), and their memory was tested with five-alternative multiple-choice questions. For each question, participants were asked to generate two answers: a single answer consisting of one alternative and a plural answer consisting of the single answer and two other alternatives. Each answer was rated for confidence (Experiment 1) or for the likelihood of being correct (Experiment 2), and one of the answers was selected for reporting. Results showed that participants used the plurality option to regulate accuracy, selecting single answers when their accuracy and confidence were high, but opting for plural answers when they were low. Although accuracy was higher for selected plural than for selected single answers, the opposite pattern was evident for confidence or likelihood ratings. This dissociation between confidence and accuracy for selected answers was the result of marked overconfidence in single answers coupled with underconfidence in plural answers. We hypothesize that these results can be attributed to overly dichotomous metacognitive beliefs about personal knowledge states that cause subjective confidence to be extreme. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
18.
19.
20.