全文获取类型
收费全文 | 27484篇 |
免费 | 2160篇 |
国内免费 | 863篇 |
专业分类
电工技术 | 1335篇 |
技术理论 | 1篇 |
综合类 | 1380篇 |
化学工业 | 4896篇 |
金属工艺 | 1349篇 |
机械仪表 | 1367篇 |
建筑科学 | 1997篇 |
矿业工程 | 589篇 |
能源动力 | 923篇 |
轻工业 | 2063篇 |
水利工程 | 352篇 |
石油天然气 | 1357篇 |
武器工业 | 118篇 |
无线电 | 3227篇 |
一般工业技术 | 3533篇 |
冶金工业 | 2059篇 |
原子能技术 | 317篇 |
自动化技术 | 3644篇 |
出版年
2024年 | 90篇 |
2023年 | 423篇 |
2022年 | 722篇 |
2021年 | 1063篇 |
2020年 | 746篇 |
2019年 | 719篇 |
2018年 | 733篇 |
2017年 | 851篇 |
2016年 | 806篇 |
2015年 | 964篇 |
2014年 | 1304篇 |
2013年 | 1767篇 |
2012年 | 1657篇 |
2011年 | 1863篇 |
2010年 | 1515篇 |
2009年 | 1549篇 |
2008年 | 1471篇 |
2007年 | 1373篇 |
2006年 | 1468篇 |
2005年 | 1256篇 |
2004年 | 918篇 |
2003年 | 845篇 |
2002年 | 841篇 |
2001年 | 587篇 |
2000年 | 570篇 |
1999年 | 645篇 |
1998年 | 616篇 |
1997年 | 500篇 |
1996年 | 494篇 |
1995年 | 375篇 |
1994年 | 333篇 |
1993年 | 232篇 |
1992年 | 200篇 |
1991年 | 130篇 |
1990年 | 126篇 |
1989年 | 105篇 |
1988年 | 112篇 |
1987年 | 76篇 |
1986年 | 73篇 |
1985年 | 47篇 |
1984年 | 60篇 |
1983年 | 41篇 |
1982年 | 40篇 |
1981年 | 27篇 |
1980年 | 23篇 |
1979年 | 26篇 |
1978年 | 15篇 |
1977年 | 20篇 |
1976年 | 20篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Ann Barrett Anuradha Prakash Deborah Sakelakos Irwin Taub Samuel Cohen Yuki Ohashi 《Food Hydrocolloids》1998,12(4):401-408
The effects of composition and thermal treatment on the water sorption and diffusional properties of idealized protein gels arranged in bilayer configurations were determined; these water binding/migration properties were related to the mechanical characteristics of the gels. Samples were prepared from whey protein concentrate (WPC), they consisted of water:WPC ratios of 1.5 to 5.67, and were thermally set for 20–60 min. Moisture migration rates from samples interfaced with filters were determined, as were moisture sorption capacities of samples immersed in water. The physical properties of the gels were assessed by uniaxial compression and microscopy. Results showed that gel strength and consequent extent of protein interaction—as affected by thermal treatment—controlled the ability of the gel structure to absorb water. Sorption was exponentially correlated with gel modulus and linearly correlated with a function of protein content, heating time, and immersion time. Rates of diffusion from interfaced gels were dependent solely on water content. It was concluded that the degree of protein interaction, whether influenced by concentration or thermal treatment, affected network extensibility and thus the capacity of the gels to act as receptors of moisture. Results have implications for the functionality of shelf-stable sandwiches and other multicomponent foods. 相似文献
92.
93.
变结构变参数设计方法及其在机械CAD中的应用 总被引:4,自引:0,他引:4
提出了一种新颖的机械结构设计思想-变结构变参数设计方法,并结合实例,阐述了变结构变参数设计的概念、原则、实施措施和意义。由此对I-deas软件包进行了二次开发,编制了发动机曲轴专用CAD软件程序,并用某型号发动机曲轴进行了验证。 相似文献
94.
Although the dams produce remarkable social and economic benefits, the threat made by unsafe dams to the life and property of people who live in the lower river area is un-negligible. Based on the monitoring data which reflect the safety condition of dams, the risk degree concept is proposed and the analysis system and model for evaluating risk degree (rate) are established in this paper by combining the reliability theory and field monitoring data. The analysis method for risk degree is presented based on Bayesian approach. A five-grade risk degree system for dam operation risk and corresponding risk degree is put forward according to the safety condition of dams. The operation risks of four cascade dams on some river are analyzed by the model and approach presented here and the result is adopted by the owner. 相似文献
95.
Marsch Lisa A.; Stephens Mary Ann Chutuape; Mudric Timothy; Strain Eric C.; Bigelow George E.; Johnson Rolley E. 《Canadian Metallurgical Quarterly》2005,13(4):293
This study examined (1) predictors of treatment outcome for opioid-dependent participants in a single-site controlled trial comparing methadone, buprenorphine, and LAAM treatments and (2) the extent to which various subpopulations of patients may have more successful outcomes with each medication. The relationships between patient demographics, drug use history, and psychological status and outcome measures of treatment retention, opiate use, and cocaine use were assessed. We believe this study to be the first to demonstrate that predictors of treatment success appear to be largely similar in LAAM, buprenorphine, and methadone treatment for opioid dependence. We did not find any factors that would strongly guide selection of one medication over others. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
97.
Jae-Hee Han Su Hong Lee A.S. Berdinsky Yong Weon Kim Ji-Beom Yoo Chong-Yun Park Jin Ju Choi Taewon Jung In Taek Han Jong Min Kim 《Diamond and Related Materials》2005,14(11-12):1891
In this report, the FE characteristics of carbon nanotubes (CNTs) treated using both thermal annealing and mechanical coatings on the as-grown CNTs systematically studied. It was found that in the high temperature annealed samples, CNTs were attacked at its root during annealing due to a small amount of oxygen, and were pulled out of the substrate in places after FE measurements because of the contact resistance. However, for the mechanically coated samples both with spin on glass (SOG) and polymethyl methacrylate (PMMA), CNTs were found to be nearly intact after FE measurements and showed reliable FE characteristics over repeatable voltage scan. The reliability of CNTs during FE could be owing to the strong adhesion of CNTs to the substrate both by SOG and PMMA coatings. 相似文献
98.
Jingjie Guo Jun Jia Hengzhi Fu Guizhong Liu Yanqing Su Hongsheng Ding 《Metallurgical and Materials Transactions A》2002,33(10):3249-3253
In this article, two key pressures, the critical pressure P
crit and the impeding pressure P
impe of elemental evaporation, are defined and studied based on the calculation relationship between the evaporation loss rate
N
m and the chamber pressure P during melting of titanium-aluminum alloys. When the chamber pressure is below P
crit or above P
impe, N
m tends to the maximum or the minimum value and remains almost unchanged. However, if P
crit<P<P
impe, with the increase of the chamber pressure, N
m declines sharply. A method has been put forward to calculate P
crit and P
impe of Al evaporation in a Ti-XAl (at pct) (X=25 to 50) melt. The calculation result shows that P
crit or P
impe is a second-order function of the molar percentage of Al and the melt temperature. 相似文献
99.
新增探明储量的经济可采储量计算方法 总被引:5,自引:0,他引:5
提出了新增探明储量有无经济可采储量的判别方法。在此基础上,通过对立已开发油田技术可采储量经济转化率与油藏空气渗透率的相关关系式和图版,根据储层的空气渗透率,计算新增探明储量的经济转化率和经济可采储量。该方法参数易取,计算简便,对于快速、准确计算新增探明储量的经济可采储量具有重要意义。 相似文献
100.