全文获取类型
收费全文 | 43651篇 |
免费 | 4554篇 |
国内免费 | 3275篇 |
专业分类
电工技术 | 2009篇 |
综合类 | 4526篇 |
化学工业 | 5215篇 |
金属工艺 | 5344篇 |
机械仪表 | 3644篇 |
建筑科学 | 6262篇 |
矿业工程 | 2775篇 |
能源动力 | 1350篇 |
轻工业 | 2433篇 |
水利工程 | 2224篇 |
石油天然气 | 2419篇 |
武器工业 | 390篇 |
无线电 | 1780篇 |
一般工业技术 | 6657篇 |
冶金工业 | 2837篇 |
原子能技术 | 472篇 |
自动化技术 | 1143篇 |
出版年
2024年 | 185篇 |
2023年 | 630篇 |
2022年 | 1955篇 |
2021年 | 1942篇 |
2020年 | 1445篇 |
2019年 | 1330篇 |
2018年 | 1254篇 |
2017年 | 1540篇 |
2016年 | 1668篇 |
2015年 | 1704篇 |
2014年 | 2487篇 |
2013年 | 2694篇 |
2012年 | 2908篇 |
2011年 | 3177篇 |
2010年 | 2411篇 |
2009年 | 2469篇 |
2008年 | 2320篇 |
2007年 | 2780篇 |
2006年 | 2431篇 |
2005年 | 2127篇 |
2004年 | 1809篇 |
2003年 | 1530篇 |
2002年 | 1362篇 |
2001年 | 1156篇 |
2000年 | 1031篇 |
1999年 | 856篇 |
1998年 | 708篇 |
1997年 | 638篇 |
1996年 | 543篇 |
1995年 | 439篇 |
1994年 | 376篇 |
1993年 | 301篇 |
1992年 | 278篇 |
1991年 | 187篇 |
1990年 | 170篇 |
1989年 | 158篇 |
1988年 | 106篇 |
1987年 | 77篇 |
1986年 | 54篇 |
1985年 | 37篇 |
1984年 | 44篇 |
1983年 | 19篇 |
1982年 | 29篇 |
1981年 | 10篇 |
1980年 | 15篇 |
1979年 | 24篇 |
1964年 | 10篇 |
1961年 | 6篇 |
1959年 | 8篇 |
1955年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Alpass Fiona; Flett Ross; Humphries Steve; Massey Claire; Morriss Stuart; Long Nigel 《Canadian Metallurgical Quarterly》2004,11(3):270
Previous studies have identified a number of different farm stressors and have reported gender and age differences in levels of stress. This study aimed to determine stress experienced by New Zealand dairy farmers, particularly in relation to adoption of new technology and its relationship to age and gender. Measures of farm stress and adoption of technology were completed by 985 dairy farmers. The highest levels of stress were reported for time pressures, machinery breakdown, weather, and government policies. Stress related to new technologies occurred rarely. Women reported more stress and higher levels of stress for understanding new technologies. There was also an increase in severity of stress with age related to new technologies. Overall, stress levels were moderate and may reflect favorable economic conditions. The findings suggest a need to tailor stress interventions to meet specific needs. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
44.
Schnurr Paula P.; Hayes Andrew F.; Lunney Carole A.; McFall Miles; Uddo Madeline 《Canadian Metallurgical Quarterly》2006,74(4):707
This study examined how change in posttraumatic stress disorder (PTSD) symptoms relates to change in quality of life. The sample consisted of 325 male Vietnam veterans with chronic PTSD who participated in a randomized trial of group psychotherapy. Latent growth modeling was used to test for synchronous effects of PTSD symptom change on psychosocial and physical health-related quality of life within the same time period and lagged effects of initial PTSD symptom change on later change in quality of life. PTSD symptoms were associated with reduced quality of life before treatment. There were synchronous effects of symptom change on change in quality of life but no significant lagged effects. Results indicate the importance of measuring quality of life in future investigations of PTSD treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
45.
Rinkenauer Gerhard; Osman Allen; Ulrich Rolf; Müller-Gethmann Hiltraut; Mattes Stefan 《Canadian Metallurgical Quarterly》2004,133(2):261
Lateralized readiness potentials (LRPs) were used to determine the stage(s) of reaction time (RT) responsible for speed-accuracy trade-offs (SATs). Speeded decisions based on several types of information were examined in 3 experiments, involving, respectively, a line discrimination task, lexical decisions, and an Erikson flanker task. Three levels of SAT were obtained in each experiment by adjusting response deadlines with an adaptive tracking algorithm. Speed stress affected the duration of RT stages both before and after the start of the LRP in all experiments. The latter effect cannot be explained by guessing strategies, by variations in response force, or as an indirect consequence of the pre-LRP effect. Contrary to most models, it suggests that SAT can occur at a late postdecisional stage. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
46.
陈训诰 《冶金标准化与质量》2004,42(1):37-40
分析材料试验机度盘偏转角度小 (准确度低 )、试样打滑、定义 (上屈服强度 -下屈服强度 -屈服强度 )模糊、不同应力速率等导致误读 ,并针对误读原因提出纠正方法。 相似文献
47.
In this work, we co‐formulated an oil‐borne copper naphthenate/permethrin wood preservative system with synthetic polymer‐based fire‐retardant additives prior to the impregnation of Pinus radiata sapwood. We evaluated what effect, if any, the preservative had upon the fire performance properties of the fire retardants and whether the fire retardants impacted on the fungicidal and termiticidal efficacy of the preservative. The fire retardants included halogenated and phosphorus‐based systems. A mass loss calorimeter, in conjunction with a thermopile, was used to measure the time to ignition and the peak heat release rate (PHRR) from which the fire performance index (FPI) was determined. The preservative properties were evaluated using termite and soil‐block decay bioassays. In summary, we found that the rate of fire growth was reduced when the fire retardants were used in combination with the wood preservative. We also found that the PHRR was a better determinant of fire performance than the FPI. The performance of the wood preservative was enhanced against fungal decay and termite attack when used in combination with the fire retardants. The fire retardants also demonstrated some wood preservative properties of their own. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
48.
49.
50.
The objective of the present work is to further explore the problem of selection of the flow stress function which will give the best agreement with experiments for a wide range of the Zener‐Hollomon parameter. Analysis of various flow stress functions was performed, with particular emphasis on the Zerilli‐Armstrong model. Inverse analysis was successfully applied to identify the flow stress model for microalloyed steels deformed in ferrite, two‐phase and austenite regions. Inverse method is applied to interpret the results of the axisymmetrical compression tests performed for HSLA steel samples on a Gleeble 3800 and Split Hopkinson Pressure Bar. Sensitivity analysis is performed based on local and global methods. The objective of the sensitivity analysis in the present study is the evaluation to what extent the selected coefficients in the rheological model influence the result of simulations. In the considered tests this result is represented by two dependent variables, the load and the shape of the sample (barrelling). It is confirmed that the Zerilli‐Armstrong equations should be applied at very high strain rates. Physical meaning is an advantage of this model. Difficulties with identification are the main disadvantage. 相似文献