全文获取类型
收费全文 | 3245篇 |
免费 | 89篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 34篇 |
综合类 | 2篇 |
化学工业 | 508篇 |
金属工艺 | 59篇 |
机械仪表 | 68篇 |
建筑科学 | 107篇 |
矿业工程 | 11篇 |
能源动力 | 81篇 |
轻工业 | 424篇 |
水利工程 | 25篇 |
石油天然气 | 8篇 |
无线电 | 238篇 |
一般工业技术 | 496篇 |
冶金工业 | 840篇 |
原子能技术 | 37篇 |
自动化技术 | 398篇 |
出版年
2022年 | 37篇 |
2021年 | 52篇 |
2020年 | 31篇 |
2019年 | 41篇 |
2018年 | 31篇 |
2017年 | 50篇 |
2016年 | 66篇 |
2015年 | 60篇 |
2014年 | 72篇 |
2013年 | 98篇 |
2012年 | 86篇 |
2011年 | 131篇 |
2010年 | 114篇 |
2009年 | 98篇 |
2008年 | 126篇 |
2007年 | 117篇 |
2006年 | 84篇 |
2005年 | 80篇 |
2004年 | 71篇 |
2003年 | 76篇 |
2002年 | 74篇 |
2001年 | 58篇 |
2000年 | 56篇 |
1999年 | 77篇 |
1998年 | 204篇 |
1997年 | 142篇 |
1996年 | 116篇 |
1995年 | 94篇 |
1994年 | 75篇 |
1993年 | 80篇 |
1992年 | 41篇 |
1991年 | 27篇 |
1990年 | 30篇 |
1989年 | 28篇 |
1988年 | 24篇 |
1987年 | 24篇 |
1986年 | 33篇 |
1985年 | 46篇 |
1984年 | 30篇 |
1983年 | 23篇 |
1981年 | 21篇 |
1980年 | 24篇 |
1978年 | 26篇 |
1977年 | 41篇 |
1976年 | 49篇 |
1975年 | 27篇 |
1972年 | 28篇 |
1971年 | 20篇 |
1970年 | 27篇 |
1969年 | 18篇 |
排序方式: 共有3336条查询结果,搜索用时 11 毫秒
1.
Effects of breed and age at slaughter on degradation of muscle lipids during processing of dry‐cured hams
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Linda Storrustløkken Hanne Marie Devle Lars Erik Gangsei Carl Fredrik Naess‐Andresen Bjørg Egelandsdal Ole Alvseike Dag Ekeberg 《International Journal of Food Science & Technology》2015,50(8):1933-1943
Hams from Landrace, Duroc and Hampshire pigs slaughtered at ages 6, 7.5 and 9 months were processed to generate Norwegian Parma‐style hams. Lipid contents and the compositions of fatty acid classes (ΣSFA, ΣMUFA, ΣPUFA) within neutral lipids, phospholipids and free fatty acids were determined. Small differences in lipid degradation and composition of the classes were revealed. However, significant sensory differences related to lipids were observed. Breed was more important than age. Dry‐cured Hampshire hams gave a more intense mature odour that may be associated with higher overall lipid degradation. Unexpectedly, these hams also demonstrated high juiciness and tenderness, which could be related to the melting characteristics of the fat. Dry‐cured Duroc hams showed a higher susceptibility towards rancidity, presumably associated with preferential oxidation of n‐6 fatty acids relative to C18:1 n‐9. Dry‐cured Landrace hams showed the lowest juiciness and tenderness, likely due to their lower fat content (marbling). 相似文献
2.
Ole Wiborg Martin O'Connell Richard Thiele Martin Wichert Gunther Kolb 《化学工程与技术》2015,38(8):1308-1314
Many critical issues need to be addressed when microstructured reactors are manufactured in large unit volumes. The most crucial of these are cost, ease of production, and reliability. The lack of breakthrough manufacturing technology to provide high‐efficiency, low‐cost, high‐precision plates is a hindrance to the early market implementation of systems requiring metallic microstructured plates. This contribution focuses on the development and optimization of a combined embossing and bending tool for the quick and continuous manufacture of easily machined plates. 相似文献
3.
4.
OL Lopez RP Brenner JT Becker RF Ulrich F Boller ST DeKosky 《Canadian Metallurgical Quarterly》1997,48(6):1521-1525
We examined whether either psychotic features (e.g., delusions and hallucinations) or EEG abnormalities are associated with more rapid progression of Alzheimer's disease (AD). AD patients with psychosis have exhibited more EEG abnormalities than those without psychosis, and both abnormal EEG and psychosis have been noted to be predictors of functional and cognitive decline in AD. Ninety-five probable AD patients participating in a longitudinal study of dementia had an EEG and a semistructured psychiatric interview at baseline. Using EEG spectral analysis, we classified records as normal/abnormal based on the parasagittal mean frequency. Patients with abnormal EEGs were more functionally (e.g., Blessed Rating Scale for activities of daily living) and cognitively (e.g., Mini-Mental State) impaired than patients with normal EEG. AD patients with psychosis were only more functionally impaired than patients without psychosis. A two-factor analysis showed no interaction between abnormal EEG and psychosis. In addition, using a Cox proportional hazard model adjusted for age and education, the presence of an abnormal EEG or psychotic symptom at study entry was associated with higher risk of reaching severe cognitive and functional impairment during follow-up. Neither abnormal EEG nor the presence of psychosis predicted death. These results indicate that both abnormal EEG and psychosis are independent predictors of disease progression but not of physical survival. 相似文献
5.
T. Braun K.-F. Becker M. Koch V. Bader R. Aschenbrenner H. Reichl 《Microelectronics Reliability》2005,45(9-11):1672
Automotive under-the-hood electronics often have to withstand temperatures up to 175 °C in combination with harsh environment conditions. This paper gives an overview about the reliability potential of epoxy based encapsulants for automotive applications. Therefore the resistance of epoxy molding compound against typical automotive fluids at temperature of use is analyzed. Six epoxy molding compounds available on the market, showing high temperature automotive potential have been carefully selected to undergo a media resistance testing. For this purpose a dedicated mold tool has been designed and manufactured to prepare these encapsulants for material testing. Thermo-mechanical, mechanical and thermal properties had been determined in initial state directly after molding and after storage in aggressive fluids typical for automotive applications as e.g. gas oil, automatic transmission fluid (ATF), brake fluid or accumulator acid at the respective temperature of use. 相似文献
6.
This paper sets out to share BT's leadership and experience by determining the identity management opportunities and issues,
then document the lessons learnt in previous deployments and recommend strategies for all types and sizes of organisation.
Today's ICT environment has created a mixed approach to access management across sectors. Browser-based any time, anywhere,
anyone access, coupled with the business need to access more systems and services across a changing infrastructure of distributed
platforms and networked services, has changed the administrative landscape. Enterprises are being forced to add administrative
support staff or invest in technology-driven process change. At the same time, users are undergoing significant change, creating
new expectations in service quality. Moreover, regulatory bodies are demanding confirmation that processes granting access
are controlled and documented. In this world of increasing demands, complexity and expectation, the service management tools,
techniques and options available to improve user access management are as varied and numerous as the issues faced by management
in their deployment.
Identity management is widely heralded as an opportunity to improve the end user experience, reduce costs, improve security
and deliver regulatory compliance — but is often misunderstood. Projects regularly fail to achieve the expected benefits.
These failures are the result of expectations being inappropriately set, deployment of solutions turning out to be more complex
or taking longer than expected, and/or products selected before required functionality has been determined.
For the larger more mature organisations, or those organisations that are the amalgamation of mergers and acquisitions, the
dilemma is where to start and what approach to take. 相似文献
7.
Comparison of two methods of surfactant administration and the effect on dosing-associated hypoxemia
M Nelson JJ Nicks MA Becker LA Vrlenich V Bhatt-Mehta RE Schumacher 《Canadian Metallurgical Quarterly》1997,17(6):450-454
OBJECTIVE: The purpose of our study was to test the hypothesis that surfactant dosing through a proximal sideport adapter on an endotracheal tube leads to more dosing-associated hypoxemia compared with a method of dosing that uses a double-lumen endotracheal tube. STUDY DESIGN: Using adequate sample size to compare significant changes in O2 saturation (power > 0.8, alpha < 0.05) we enrolled 36 infants with respiratory distress syndrome in this randomized trial. A 10% change in O2 saturation was considered clinically significant. Nineteen infants received 38 doses of surfactant through the sideport adapter. Seventeen infants received 31 doses of surfactant through the nonventilation lumen of a double-lumen endotracheal tube. Two main outcome measures were assessed: time-averaged O2 saturation values 30 minutes after dosing and the largest absolute fall in O2 saturation for each patient. RESULTS AND CONCLUSIONS: Time-averaged O2 saturation measures were higher in the proximal sideport group (p = 0.02), but the magnitude of difference was probably not clinically significant. No significant difference was detected between groups when we compared largest absolute drop in O2 saturation. Secondary analyses found no effect of birth weight or dose number (second vs third dose) on either outcome measure. 相似文献
8.
9.
MineSet aids knowledge discovery and supports decision making based on relational data. It uses visualization and data mining to arrive at interesting results. Providing diverse visualization tools lets users choose the most appropriate method for a given problem. The client-server architecture performs most of the computationally intensive tasks on a server, while the processed results return to the client for visualization. The paper discusses MineSet database visualization and data mining visualization 相似文献
10.
CM Wheeler CA Parmenter WC Hunt TM Becker CE Greer A Hildesheim MM Manos 《Canadian Metallurgical Quarterly》1993,20(5):286-289
OBJECTIVES: To confirm the risk factors for genital human papillomavirus (HPV) infection. GOAL OF THIS STUDY: To investigate risk factors for HPV detection apart from the correlated risk factors for cervical neoplasia. STUDY DESIGN: Cervical human papillomavirus (HPV) DNA was assessed in 357 cytologically normal women attending the University of New Mexico student health center. Cervical swab samples were obtained for HPV DNA detection and typing using a PCR-based DNA amplification system. Possible determinants of cervical HPV were examined including age, ethnicity, history of sexually transmitted disease, oral contraceptive use, smoking, age at first intercourse, lifetime number of sex partners, marital status, and history of pregnancy. RESULTS: A 44.3% overall prevalence of cervical HPV was observed. On univariate analysis, factors associated with increasing HPV prevalence included higher lifetime number of sex partners and single marital status. After adjustment for potential confounding variables, we found that HPV prevalence increased with higher lifetime number of sexual partners. CONCLUSION: These findings, along with those from the companion reports in this issue of the journal, support the sexual route of transmission of the virus. 相似文献