全文获取类型
收费全文 | 1156篇 |
免费 | 47篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
综合类 | 2篇 |
化学工业 | 245篇 |
金属工艺 | 20篇 |
机械仪表 | 20篇 |
建筑科学 | 120篇 |
矿业工程 | 1篇 |
能源动力 | 29篇 |
轻工业 | 111篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 114篇 |
一般工业技术 | 191篇 |
冶金工业 | 90篇 |
原子能技术 | 19篇 |
自动化技术 | 216篇 |
出版年
2023年 | 17篇 |
2022年 | 19篇 |
2021年 | 36篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 14篇 |
2017年 | 17篇 |
2016年 | 39篇 |
2015年 | 27篇 |
2014年 | 34篇 |
2013年 | 62篇 |
2012年 | 45篇 |
2011年 | 84篇 |
2010年 | 59篇 |
2009年 | 65篇 |
2008年 | 60篇 |
2007年 | 58篇 |
2006年 | 51篇 |
2005年 | 49篇 |
2004年 | 41篇 |
2003年 | 31篇 |
2002年 | 28篇 |
2001年 | 22篇 |
2000年 | 19篇 |
1999年 | 15篇 |
1998年 | 36篇 |
1997年 | 32篇 |
1996年 | 19篇 |
1995年 | 15篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1970年 | 4篇 |
1942年 | 3篇 |
1941年 | 7篇 |
1940年 | 10篇 |
1939年 | 10篇 |
排序方式: 共有1205条查询结果,搜索用时 31 毫秒
61.
62.
63.
Thomas Beer Tobias Meisen Rudolf Reinhard Sergey Konovalov Daniel Schilberg Sabina Jeschke Torsten Kuhlen Christian Bischof 《Production Engineering》2011,5(4):383-391
Computational simulations are used for the optimization of production processes in order to significantly reduce the need
for costly experimental optimization approaches. Yet individual simulations can rarely describe more than a single production
step. A set of simulations has to be coupled to each other to form a contiguous representation of a process chain. Eventually,
simulated results have to be analyzed by domain experts to gather insight from the preformed computations. In this paper,
we propose an IT infrastructure and software tools that aim at a rather non-intrusive way of coupling resources and domain
expert’s knowledge to enable the collaborative setup, execution and analysis of distributed simulation chains. We illustrate
the approach in the domain of materials processing. Beyond means originating from the domain of GRID computing for resource
management, a data integration component assures semantic data integrity between the simulation steps and stores simulation
data in an application independent way. Thus, we can transform this data into native formats for each simulation tool, and
finally into a format that allows for contiguous visualizations and an intuitive, comprehensive analysis of complete simulated
process chains. 相似文献
64.
Eric Biehler Frédéric Mayer Lucien Hoffmann Elmar Krause Torsten Bohn 《Journal of food science》2010,75(1):C55-C61
ABSTRACT: Carotenoids are C-40 tetraterpenoid compounds with potential health beneficial effects. Major dietary sources include a variety of fruits and vegetables. Rapid screening methods are therefore desired, but their accuracy varies depending on the carotenoid profile and the matrix of the plant food. In the present study, 3 different methods were compared, all based on a rapid extraction protocol and spectrophotometric measurements to determine the total amount carotenoids present in fruits and vegetables (n = 28), either with or without chlorophyll. Published methods (a) Lichtenthaler and (b) Hornero-Méndez and Mínguez-Mosquera were compared with a newly developed method (method c) based on the average molar absorption coefficient (135310 Lcm−1mol−1) and wavelength (450 nm in acetone), for the 5 predominant carotenoid species (beta-carotene, zeaxanthin, lycopene, lutein, beta-cryptoxanthin) in the investigated foods. All results were compared to HPLC (method d). To avoid overestimating carotenoid concentrations due to chlorophyll A and B presence, the effect of saponification was studied for all methods. Overall, saponification led to significant carotenoid losses (12.6 ± 0.9%). Methods a, b, c, and d yielded 5.1 ± 0.4 mg/100 g, 4.6 ± 0.5 mg/100 g, 4.3 ± 0.5 mg/100 g, and 4.2 ± 0.5 mg/100 g total carotenoids, respectively, with method a leading to significant higher mean concentrations compared to all other methods (P < 0.001, Bonferroni) with methods b and c being not significantly different and highly correlated compared to HPLC (> r = 0.95). Similar results were found when stratifying for chlorophyll content and fruits compared with vegetables, however, accuracy varied for individual fruits, highlighting the limitation to use the same method for all plant foods. Practical Application: This study presents a comparison of various rapid spectrophotometric measurements to determine total carotenoid content in various fruits and vegetables and could aid in the selection of the appropriate method for individual plant foods with different carotenoid profile and matrices. 相似文献
65.
Guenther K Heinke V Thiele B Kleist E Prast H Raecker T 《Environmental science & technology》2002,36(8):1676-1680
4-Nonylphenols (NPs) are common products of biodegradation of a widely used group of nonionic surfactants, the nonylphenol ethoxylates (NPEs). These compounds are known to be persistent, toxic, and estrogen active. There is a worldwide scientific and public discussion on the potential consequences of human long term dietary exposure to such endocrine disrupters. Despite numerous determinations of NPs in environmental samples no systematical reports exist relating to concentrations of NPs in food. We analyzed NPs in 60 different foodstuff commercially available in Germany. The results indicate that NPs are ubiquitous in food. The concentrations of NPs on a fresh weight basis varied between 0.1 and 19.4 microg/kg regardless of the fat content of the foodstuff. Based on data on German food consumption rates and these first analyses of NPs in food, the daily intake for an adult was calculated to be 7.5 microg/day NPs. For infants exclusively fed with breast milk or infant formulas daily intakes of 0.2 microg/day and 1.4 microg/day NPs, respectively, can be estimated. 相似文献
66.
Peter Hocke Klaus-Rainer Br?utigam Torsten Fleischer Anna Schleisiek 《e & i Elektrotechnik und Informationstechnik》2002,119(9):a18
SciencenewsTriz*-Check up
Seminar zum systematischen Erfinden 相似文献67.
Johnson Mallory O.; Elliott Timothy R.; Neilands Torsten B.; Morin Stephen F.; Chesney Margaret A. 《Canadian Metallurgical Quarterly》2006,25(3):355
HIV medication adherence remains a challenge and limits the degree to which treatment benefit can be maximized. This study tested an explanatory model of HIV medication adherence using a social problem-solving (SPS) framework. Associations of SPS with adherence are hypothesized to be direct and/or indirect via psychological health. HIV+ adults were interviewed using validated measures of SPS, psychological health, and antiretroviral therapy (ART) medication adherence. Structural equation modeling (SEM) techniques were used to test hypothesized relationships and to evaluate overall fit of the model to the data. SEM supported an indirect association (but not direct) of SPS on adherence via psychological health among the 545 HIV+ adults included in the analyses. Overall, the findings resulted in a model of adherence that offered very good fit to the data and correctly classified 97% of the cases as adherent versus nonadherent. Results support the use of SPS as a conceptual framework for understanding adherence to ART. Findings offer rationale and direction for SPS interventions to enhance adherence by improving psychological health. Such approaches, if effective, have the potential to positively impact psychological well being and adherence, thereby maximizing clinical benefit from treatment, which is linked to lower mortality from AIDS. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
68.
WR Holcomb JC Parker GB Leong J Thiele J Higdon 《Canadian Metallurgical Quarterly》1998,49(7):929-934
OBJECTIVE: Relationships among different dimensions of patient satisfaction and selected demographic, clinical, and outcome variables were explored in a sample of severely ill people receiving inpatient psychiatric services. METHOD: The sample consisted of 81 patients admitted to and discharged from an inpatient psychiatric unit at a midwestern Veterans Affairs medical center. Stepwise multiple regression was used to examine the relationship between patient satisfaction and self-reported changes in quality of life, symptomatology, and level of functioning as measured by the Treatment Outcome Profile. Other variables such as diagnosis, length of stay, employment, living situation, and prior psychiatric and substance abuse treatment were also considered. A subsample of the most satisfied and dissatisfied patients was chosen to further explore variables contributing to satisfaction with services. RESULTS: Patient satisfaction was related to initial level of functioning, certain diagnoses, and treatment gains. Clinicians were highly accurate in identifying patients who were satisfied, based on blind chart reviews. CONCLUSIONS: This study underscores the significant relationships between patient satisfaction, psychiatric diagnosis, and other outcome measures, and argues for the validity and utility of patient satisfaction measures in assessing the efficacy of inpatient care. 相似文献
69.
A method of analyzing Yagi-Uda-type antennas is presented. Since the Yagi-Uda array is a fairly well-known antenna, it is used as an example to demonstrate the application and accuracy of the method. However, the method of solution is not limited to a planar array, such as the Yagi, but can be applied to arrays of nonplanar linear elements. The approach taken in analyzing Yagi-Uda antennas is based on rigorous equations for the electric field radiated by the elements in the array. All interactions are taken into account. Calculated results are presented for the Yagi-Uda array that show excellent agreement with experimental results reported in the literature. In addition, the dependence of the far-field patterns on the phase velocity is shown. It is also demonstrated that the phase velocity is generally nonuniform along the array. 相似文献
70.
Torsten Söderström 《Automatica》1981,17(2):387-388
Bohlin has recently suggested an appealing method for model structure selection. It is shown that the method can be interpreted as a modified F-test. The minimal loss in a larger model structure is substituted by an estimate. The estimate is obtained by minimization of a quadratic approximation of the loss function. 相似文献