全文获取类型
收费全文 | 1503篇 |
免费 | 29篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 8篇 |
综合类 | 3篇 |
化学工业 | 198篇 |
金属工艺 | 9篇 |
机械仪表 | 10篇 |
建筑科学 | 86篇 |
矿业工程 | 1篇 |
能源动力 | 23篇 |
轻工业 | 150篇 |
水利工程 | 9篇 |
石油天然气 | 25篇 |
无线电 | 39篇 |
一般工业技术 | 135篇 |
冶金工业 | 701篇 |
原子能技术 | 4篇 |
自动化技术 | 132篇 |
出版年
2023年 | 13篇 |
2022年 | 25篇 |
2021年 | 41篇 |
2020年 | 17篇 |
2019年 | 23篇 |
2018年 | 21篇 |
2017年 | 18篇 |
2016年 | 22篇 |
2015年 | 25篇 |
2014年 | 32篇 |
2013年 | 74篇 |
2012年 | 50篇 |
2011年 | 60篇 |
2010年 | 47篇 |
2009年 | 71篇 |
2008年 | 77篇 |
2007年 | 69篇 |
2006年 | 54篇 |
2005年 | 57篇 |
2004年 | 48篇 |
2003年 | 59篇 |
2002年 | 40篇 |
2001年 | 39篇 |
2000年 | 37篇 |
1999年 | 40篇 |
1998年 | 37篇 |
1997年 | 30篇 |
1996年 | 47篇 |
1995年 | 33篇 |
1994年 | 36篇 |
1993年 | 38篇 |
1992年 | 25篇 |
1991年 | 9篇 |
1990年 | 29篇 |
1989年 | 27篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 19篇 |
1985年 | 16篇 |
1984年 | 16篇 |
1983年 | 16篇 |
1982年 | 12篇 |
1981年 | 14篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有1533条查询结果,搜索用时 15 毫秒
81.
82.
Fare TL Coffey EM Dai H He YD Kessler DA Kilian KA Koch JE LeProust E Marton MJ Meyer MR Stoughton RB Tokiwa GY Wang Y 《Analytical chemistry》2003,75(17):4672-4675
A data anomaly was observed that affected the uniformity and reproducibility of fluorescent signal across DNA microarrays. Results from experimental sets designed to identify potential causes (from microarray production to array scanning) indicated that the anomaly was linked to a batch process; further work allowed us to localize the effect to the posthybridization array stringency washes. Ozone levels were monitored and highly correlated with the batch effect. Controlled exposures of microarrays to ozone confirmed this factor as the root cause, and we present data that show susceptibility of a class of cyanine dyes (e.g., Cy5, Alexa 647) to ozone levels as low as 5-10 ppb for periods as short as 10-30 s. Other cyanine dyes (e.g., Cy3, Alexa 555) were not significantly affected until higher ozone levels (> 100 ppb). To address this environmental effect, laboratory ozone levels should be kept below 2 ppb (e.g., with filters in HVAC) to achieve high quality microarray data. 相似文献
83.
Taylor Steven; Zvolensky Michael J.; Cox Brian J.; Deacon Brett; Heimberg Richard G.; Ledley Deborah Roth; Abramowitz Jonathan S.; Holaway Robert M.; Sandin Bonifacio; Stewart Sherry H.; Coles Meredith; Eng Winnie; Daly Erin S.; Arrindell Willem A.; Bouvard Martine; Cardenas Samuel Jurado 《Canadian Metallurgical Quarterly》2007,19(2):176
Accumulating evidence suggests that anxiety sensitivity (fear of arousal-related sensations) plays an important role in many clinical conditions, particularly anxiety disorders. Research has increasingly focused on how the basic dimensions of anxiety sensitivity are related to various forms of psychopathology. Such work has been hampered because the original measure--the Anxiety Sensitivity Index (ASI)--was not designed to be multidimensional. Subsequently developed multidimensional measures have unstable factor structures or measure only a subset of the most widely replicated factors. Therefore, the authors developed, via factor analysis of responses from U.S. and Canadian nonclinical participants (n = 2,361), an 18-item measure, the ASI-3, which assesses the 3 factors best replicated in previous research: Physical, Cognitive, and Social Concerns. Factorial validity of the ASI-3 was supported by confirmatory factor analyses of 6 replication samples, including nonclinical samples from the United States and Canada, France, Mexico, the Netherlands, and Spain (n = 4,494) and a clinical sample from the United States and Canada (n = 390). The ASI-3 displayed generally good performance on other indices of reliability and validity, along with evidence of improved psychometric properties over the original ASI. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
84.
Genetic algorithms are a technique for search and optimization based on the Darwinian principle of natural selection. They are iterative search procedures that maintain a population of candidate solutions. The best or most fit solutions in that population are then used as the basis for the next generation of solutions. The next generation is formed using the genetic operators reproduction, crossover, and mutation. Genetic algorithms have been successfully applied to engineering search and optimization problems. This paper presents a discussion of the basic theory of genetic algorithms and presents a genetic algorithm solution of a lumber cutting optimization problem. Dimensional lumber is assigned a grade that represents its physical properties. A grade is assigned to every board segment of a specific length. The board is then cut in various locations in order to maximize its value, A genetic algorithm was used to determine the cutting patterns that would maximize the board value. 相似文献
85.
Extends a study by L. Gannon et al (see record 1992-23274-001) by examining the sex of Ss in American Psychological Association (APA) journals publishing original human studies research and by sampling all APA division journals publishing such research. Two issues of each APA and APA division journal published in 1990 were examined, yielding a sample of 504 articles from 26 journals. 79 cases (9.86%) clearly indicated using Ss of only 1 sex, 440 cases (54.93%) used both male and female Ss and reported sex fully, and 44 cases (5.49%) indicated using Ss of each sex without reporting exact numbers. The evidence suggests that there remains a significant tendency to consider male Ss as "normative," and results obtained from them generally applicable, whereas female Ss are somehow "different," and results obtained from them are specific to female Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
86.
Monday Eze Charles Okunbor Deborah Aleburu Olubukola Adekola Ibrahim Ramon Nneka Richard-Nnabu Oghenetega Avwokuruaye Abisola Olayiwola Rume Yoro Esomu Solomon 《计算机系统科学与工程》2022,41(2):595-609
This work demonstrates in practical terms the evolutionary concepts and computational applications of Parametric Curves. Specific cases were drawn from higher order parametric Bezier curves of degrees 2 and above. Bezier curves find real life applications in diverse areas of Engineering and Computer Science, such as computer graphics, robotics, animations, virtual reality, among others. Some of the evolutionary issues explored in this work are in the areas of parametric equations derivations, proof of related theorems, first and second order calculus related computations, among others. A Practical case is demonstrated using a graphical design, physical hand sketching, and programmatic implementation of two opposite-faced handless cups, all evolved using quadratic Bezier curves. The actual drawing was realized using web graphics canvas programming based on HTML 5 and JavaScript. This work will no doubt find relevance in computational researches in the areas of graphics, web programming, automated theorem proofs, robotic motions, among others. 相似文献
87.
Metformin Reduces Lipogenesis Markers in Obese Mice Fed a Low-Carbohydrate and High-Fat Diet 下载免费PDF全文
Karla Nayara de Oliveira Santana Deborah Farias Lelis Keila Lopes Mendes Jamille Fernandes Lula Alanna Fernandes Paraíso João Marcus Oliveira Andrade John David Feltenberger Junio Cota Diego Vicente da Costa Alfredo Mauricio Batista de Paula André Luiz Sena Guimarães Sérgio Henrique Sousa Santos 《Lipids》2016,51(12):1375-1384
Lipogenesis is the process by which fatty acids are synthesized. In metabolic syndrome, an insulin resistant state along with high plasma levels of free fatty acids (FFA) and hyperglycemia may contribute to the lipogenic process. The aim of the present study was to investigate the effects of oral administration of metformin on the expression of lipogenic genes and glycemic profile in mice fed with low‐carbohydrate high‐fat diet by evaluating their metabolic profile. SWISS male mice were divided into 4 groups (N = 7) that were fed with standard (ST), standard plus metformin (ST + MET), low‐carbohydrate high‐fat diet (LCHFD) and low‐carbohydrate high‐fat diet plus metformin (LCHFD + MET) (100 mg kg?1 diet) diets respectively. Food intake, body weight and blood parameters, such as glucose tolerance, insulin sensitivity, glucose, HDL‐c, total cholesterol, triglycerides, ASL and ALT levels were assessed. Histological analyses were performed on hematoxylin and eosin‐stained epididymal adipose tissue histological specimens. The expression levels of peroxisome proliferator‐activated receptor (PPARγ), sterol regulatory element‐binding protein 1 (SREBP1), fatty acid synthase (FAS) and acetyl‐CoA carboxylase (ACC), were assessed by RT‐PCR. This study showed that metformin decreased adipocyte area, body weight and food consumption in obese animals when compared to the standard group. Furthermore, the expression of lipogenic markers in adipose tissue were diminished in obese animals treated with metformin. This data showed that oral administration of metformin improved glucose and lipid metabolic parameters in white adipose tissue by reducing the expression of lipogenesis markers, suggesting an important clinical application of MET in treating obesity‐related diseases in metabolic syndrome. 相似文献
88.
89.
Susanna K. P. Lau Kim-Chung Lee George C. S. Lo Vanessa S. Y. Ding Wang-Ngai Chow Tony Y. H. Ke Shirly O. T. Curreem Kelvin K. W. To Deborah T. Y. Ho Siddharth Sridhar Sally C. Y. Wong Jasper F. W. Chan Ivan F. N. Hung Kong-Hung Sze Ching-Wan Lam Kwok-Yung Yuen Patrick C. Y. Woo 《International journal of molecular sciences》2016,17(3)
To identify potential biomarkers for improving diagnosis of melioidosis, we compared plasma metabolome profiles of melioidosis patients compared to patients with other bacteremia and controls without active infection, using ultra-high-performance liquid chromatography-electrospray ionization-quadruple time-of-flight mass spectrometry. Principal component analysis (PCA) showed that the metabolomic profiles of melioidosis patients are distinguishable from bacteremia patients and controls. Using multivariate and univariate analysis, 12 significant metabolites from four lipid classes, acylcarnitine (n = 6), lysophosphatidylethanolamine (LysoPE) (n = 3), sphingomyelins (SM) (n = 2) and phosphatidylcholine (PC) (n = 1), with significantly higher levels in melioidosis patients than bacteremia patients and controls, were identified. Ten of the 12 metabolites showed area-under-receiver operating characteristic curve (AUC) >0.80 when compared both between melioidosis and bacteremia patients, and between melioidosis patients and controls. SM(d18:2/16:0) possessed the largest AUC when compared, both between melioidosis and bacteremia patients (AUC 0.998, sensitivity 100% and specificity 91.7%), and between melioidosis patients and controls (AUC 1.000, sensitivity 96.7% and specificity 100%). Our results indicate that metabolome profiling might serve as a promising approach for diagnosis of melioidosis using patient plasma, with SM(d18:2/16:0) representing a potential biomarker. Since the 12 metabolites were related to various pathways for energy and lipid metabolism, further studies may reveal their possible role in the pathogenesis and host response in melioidosis. 相似文献
90.
Suzanne Liebowitz Taylor Deborah A. Dahl Mark Lipshutz Carl Weir Lewis M. Norton Roslyn Weidner Nilson Marcia C. Linebarger 《Artificial Intelligence Review》1994,8(2-3):255-276
Document understanding, the interpretation of a document from its image form, is a technology area which benefits greatly from the integration of natural language processing with image processing. We have developed a prototype of an Intelligent Document Understanding System (IDUS) which employs several technologies: image processing, optical character recognition, document structure analysis and text understanding in a cooperative fashion. This paper discusses those areas of research during development of IDUS where we have found the most benefit from the integration of natural language processing and image processing: document structure analysis, optical character recognition (OCR) correction, and text analysis. We also discuss two applications which are supported by IDUS: text retrieval and automatic generation of hypertext links 相似文献