全文获取类型
收费全文 | 566996篇 |
免费 | 6286篇 |
国内免费 | 1004篇 |
专业分类
电工技术 | 10512篇 |
综合类 | 466篇 |
化学工业 | 90113篇 |
金属工艺 | 23342篇 |
机械仪表 | 18511篇 |
建筑科学 | 12532篇 |
矿业工程 | 4312篇 |
能源动力 | 14438篇 |
轻工业 | 45761篇 |
水利工程 | 6941篇 |
石油天然气 | 14961篇 |
武器工业 | 39篇 |
无线电 | 60314篇 |
一般工业技术 | 116305篇 |
冶金工业 | 95562篇 |
原子能技术 | 14692篇 |
自动化技术 | 45485篇 |
出版年
2021年 | 5494篇 |
2019年 | 5275篇 |
2018年 | 9215篇 |
2017年 | 9415篇 |
2016年 | 9845篇 |
2015年 | 6032篇 |
2014年 | 10259篇 |
2013年 | 26120篇 |
2012年 | 15788篇 |
2011年 | 21125篇 |
2010年 | 16988篇 |
2009年 | 18836篇 |
2008年 | 19083篇 |
2007年 | 18780篇 |
2006年 | 16300篇 |
2005年 | 14752篇 |
2004年 | 14017篇 |
2003年 | 13700篇 |
2002年 | 13263篇 |
2001年 | 12854篇 |
2000年 | 12330篇 |
1999年 | 12011篇 |
1998年 | 27653篇 |
1997年 | 20039篇 |
1996年 | 15628篇 |
1995年 | 12009篇 |
1994年 | 10860篇 |
1993年 | 10613篇 |
1992年 | 8332篇 |
1991年 | 8103篇 |
1990年 | 7991篇 |
1989年 | 7763篇 |
1988年 | 7478篇 |
1987年 | 6747篇 |
1986年 | 6533篇 |
1985年 | 7390篇 |
1984年 | 6700篇 |
1983年 | 6437篇 |
1982年 | 5776篇 |
1981年 | 5896篇 |
1980年 | 5630篇 |
1979年 | 5733篇 |
1978年 | 5663篇 |
1977年 | 6178篇 |
1976年 | 7685篇 |
1975年 | 5108篇 |
1974年 | 4903篇 |
1973年 | 4980篇 |
1972年 | 4279篇 |
1971年 | 4038篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
Joo H. Kang Eujin Um Alexander Diaz Harry Driscoll Melissa J. Rodas Karel Domansky Alexander L. Watters Michael Super Howard A. Stone Donald E. Ingber 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(42):5657-5666
Magnetic nanoparticles have been employed to capture pathogens for many biological applications; however, optimal particle sizes have been determined empirically in specific capturing protocols. Here, a theoretical model that simulates capture of bacteria is described and used to calculate bacterial collision frequencies and magnetophoretic properties for a range of particle sizes. The model predicts that particles with a diameter of 460 nm should produce optimal separation of bacteria in buffer flowing at 1 L h−1. Validating the predictive power of the model, Staphylococcus aureus is separated from buffer and blood flowing through magnetic capture devices using six different sizes of magnetic particles. Experimental magnetic separation in buffer conditions confirms that particles with a diameter closest to the predicted optimal particle size provide the most effective capture. Modeling the capturing process in plasma and blood by introducing empirical constants (ce), which integrate the interfering effects of biological components on the binding kinetics of magnetic beads to bacteria, smaller beads with 50 nm diameters are predicted that exhibit maximum magnetic separation of bacteria from blood and experimentally validated this trend. The predictive power of the model suggests its utility for the future design of magnetic separation for diagnostic and therapeutic applications. 相似文献
86.
87.
High‐intensity sweeteners in espresso coffee: ideal and equivalent sweetness and time–intensity analysis 下载免费PDF全文
Bruna M. Azevedo Flávio L. Schmidt Helena M. A. Bolini 《International Journal of Food Science & Technology》2015,50(6):1374-1381
The efficient substitution of sucrose by a sweetener in beverages requires the application of some sensory techniques. First, one must determine the concentrations of the sweeteners under study, equivalent in sweetness to the ideal sucrose concentration. In addition, it is fundamental to determine which is most similar to sucrose. The objectives of this study were to determine the ideal sweetness for espresso coffee and the equivalent concentrations in sweetness of different sweeteners, as well as characterise the time–intensity profile of each sweetener in relation to sweetness. The sweeteners evaluated were sucralose, aspartame, neotame, a cyclamate/saccharin mixture (2:1) and stevia. The sucrose concentration considered ideal by consumers was 12.5% (w/v), and the equivalent concentrations of the sweeteners were 0.0159% for sucralose, 0.0549% for aspartame, 0.0016% for neotame, 0.0359% for the cyclamate/saccharin mixture and 0.0998% for stevia. The time–intensity analysis indicated that possibly the sweeteners neotame, aspartame and sucralose would be the best substitutes for sucrose. 相似文献
88.
89.
90.
Precil Diego M. M. Neves Fernanda M. Freitas Christiane A. Kojima Beatriz L. Carmello Rodrigo Bazan Pasqual Barretti Luis C. Martin 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(1):143-145
Antibiotics are potentially a cause of neurotoxicity in dialysis patients, the most common are the beta‐lactams as ceftazidime and cefepime, and few cases have been reported after piperacillin/tazobactam use. This report presents a case of a hypertensive and diabetic 67‐year‐old woman in regular hemodialysis, which previously had a stroke. She was hospitalized presenting pneumonia, which was initially treated with cefepime. Two days after treatment, she presented dysarthria, left hemiparesis, ataxia, and IX and X cranial nerves paresis. Computed tomography showed no acute lesions and cefepime neurotoxicity was hypothesized, and the antibiotic was replaced by piperacillin/tazobactam. The neurologic signs disappeared; however, 4 days after with piperacillin/tazobactam treatment, the neurological manifestations returned. A new computed tomography showed no new lesions, and the second antibiotic regimen withdrawn. After two hemodialysis sessions, the patient completely recovered from neurological manifestations. The patient presented sequentially neurotoxicity caused by two beta‐lactams antibiotics. This report meant to alert clinicians that these antibiotics have dangerous neurological effects in chronic kidney disease patients. 相似文献