全文获取类型
收费全文 | 1751篇 |
免费 | 107篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 426篇 |
金属工艺 | 36篇 |
机械仪表 | 30篇 |
建筑科学 | 65篇 |
矿业工程 | 2篇 |
能源动力 | 53篇 |
轻工业 | 147篇 |
水利工程 | 7篇 |
石油天然气 | 3篇 |
无线电 | 206篇 |
一般工业技术 | 354篇 |
冶金工业 | 93篇 |
原子能技术 | 23篇 |
自动化技术 | 402篇 |
出版年
2023年 | 22篇 |
2022年 | 38篇 |
2021年 | 37篇 |
2020年 | 50篇 |
2019年 | 51篇 |
2018年 | 55篇 |
2017年 | 65篇 |
2016年 | 66篇 |
2015年 | 53篇 |
2014年 | 63篇 |
2013年 | 125篇 |
2012年 | 109篇 |
2011年 | 151篇 |
2010年 | 99篇 |
2009年 | 98篇 |
2008年 | 111篇 |
2007年 | 87篇 |
2006年 | 87篇 |
2005年 | 72篇 |
2004年 | 58篇 |
2003年 | 48篇 |
2002年 | 39篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 25篇 |
1998年 | 24篇 |
1997年 | 35篇 |
1996年 | 22篇 |
1995年 | 16篇 |
1994年 | 18篇 |
1993年 | 18篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1859条查询结果,搜索用时 15 毫秒
81.
82.
83.
Antimicrobial Activity of Nisin and Natamycin Incorporated Sodium Caseinate Extrusion‐Blown Films: A Comparative Study with Heat‐Pressed/Solution Cast Films 下载免费PDF全文
Basak Yilin Colak Pierre Peynichou Sophie Galland Nadia Oulahal Frédéric Prochazka Pascal Degraeve 《Journal of food science》2016,81(5):E1141-E1150
Antimicrobial edible films based on sodium caseinate, glycerol, and 2 food preservatives (nisin or natamycin) were prepared by classical thermomechanical processes. Food preservatives were compounded (at 65 °C for 2.5 min) with sodium caseinate in a twin‐screw extruder. Anti‐Listeria activity assays revealed a partial inactivation of nisin following compounding. Thermoplastic pellets containing food preservatives were then used to manufacture films either by blown‐film extrusion process or by heat‐press. After 24 h of incubation on agar plates, the diameters of K. rhizophila growth inhibition zones around nisin‐incorporated films prepared by solution casting (control), extrusion blowing or heat pressing at 80 °C for 7 min of nisin‐containing pellets were 15.5 ± 0.9, 9.8 ± 0.2, and 8.6 ± 1.0 mm, respectively. Since heat‐pressing for 7 min at 80 °C of nisin‐incorporated pellets did not further inactivate nisin, this indicates that nisin inactivation during extrusion‐blowing was limited. Moreover, the lower diameter of the K. rhizophila growth inhibition zone around films prepared with nisin‐containing pellets compared to that observed around films directly prepared by solution casting confirms that nisin inactivation mainly occurred during the compounding step. Natamycin‐containing thermoplastic films inhibited Aspergillus niger growth; however, by contrast with nisin‐containing films, heat‐pressed films had higher inhibition zone diameters than blown films, therefore suggesting a partial inactivation of natamycin during extrusion‐blowing. 相似文献
84.
Four different commercial resin formulations namely cross-linked polyvinyl acetate (XPVAc), melamine urea formaldehyde (MUF), urea formaldehyde (UF) and melamine formaldehyde (MF) were used to produce laminated veneer lumber (LVL) from yellow poplar veneers in the laboratory. Physical and mechanical properties were evaluated using ASTM (D 1037, D 906, D 5456) standards and compared. Internal bond, tensile shear and block shear strengths of specimens subjected to accelerated (boiled water) and cyclic (repeated cold water) conditions were also determined. Strength properties of yellow poplar LVL were improved compared with the solid wood. The properties of XPVAc bonded LVL were superior or comparable to the thermosetting adhesives. This study clearly indicated that cross-linked PVAc can be used to manufacture LVL with acceptable properties. 相似文献
85.
The sciatic nerve of rats fed sunflower oil (6 mg 18∶3n−3/100 g of diet) presented dramatic alterations in the long chain
polyunsaturated fatty acids in comparison with those fed soy oil (130 mg 18∶3n−3/100 g of diet). In both 15-day-old and 60-day-old
animals fed sunflower oil, 22∶6n−3 (cervonic acid) was fourfold less, 22∶5n−6 was 10-fold greater; adrenic acid (22∶4n−6)
was slightly greater and arachidonic acid (20∶4n−6) was close to that in rats fed soy oil. The percentage distribution of
total polyunsaturated fatty acids as well as the individual saturated and monounsaturated fatty acids were the same in both
groups.
When the sunflower oil-fed animals were switched to a soy oil-containing diet for either 15 or 60 days, the percentage distribution
of 22∶6n−3 increased slowly to reach the control value 2.5 months later. Conversely 22∶5n−6 decreased slowly. The decay of
22∶5n−6 was more rapid than the increase of 22∶6n−3. 相似文献
86.
Amyloid beta peptide (Abeta) fibril formation is widely believed to be the causative event of Alzheimer's disease pathogenesis. Therapeutic approaches are therefore in development that target various sites in the production and aggregation of Abeta. Herein we present a high-throughput screening tool to generate novel hit compounds that block Abeta fibril formation. This tool is an application for our fibril model (Abeta(16-37)Y(20)K(22)K(24))(4), which is a covalent assembly of four Abeta fragments. With this tool, screening studies are complete within one hour, as opposed to days with native Abeta(1-40). A Z' factor of 0.84+/-0.03 was determined for fibril formation and inhibition, followed by the reporter molecule thioflavin T. Herein we also describe the analysis of a broad range of reported inhibitors and non-inhibitors of Abeta fibril formation to test the validity of the system. 相似文献
87.
Surrogate endpoints in oncology research and practice have garnered increasing attention over the past two decades. This activity has largely been driven by the promise surrogate endpoints appear to hold: the potential to get new therapies to seriously ill patients more rapidly. However, uncertainties abound. Even agreeing upon a definition of a "valid" surrogate endpoint has not been a straightforward exercise; this article begins by highlighting differences in how this term has been previously captured and applied, as well as laying out the basic criteria essential for its application in advanced colorectal cancer. Ideally, these elements include (but are not limited to) ease of measurement, rapid indication of treatment effect, and, most importantly, reliable and consistent prediction of the true impact of a treatment on the ultimate outcome of interest: overall survival. The strengths and weaknesses of current potential surrogate endpoints in advanced colorectal cancer, including performance status, carcinoembryonic antigen plasma level, overall response rate, time to progression, and disease-free survival, are each considered in turn. Finally, limitations of surrogate endpoints in the clinical setting, including challenges in extrapolation to new therapies, and the incomplete provision of information about potential adverse effects, are discussed. Work remains to be done between physicians and statisticians to bridge the gap between that which is statistically demonstrable and that which will be clinically useful.The term ;surrogate endpoint' was virtually unknown by most oncologists 15 years ago. A search in PubMed [http://www.ncbi.nlm.nih.gov] based on the words ;surrogate and cancer' shows that more than 2000 papers were published in medical journals in the last 20 years, with a dramatic increase of interest in the last five years. Interestingly, the same trend is observed when the words ;surrogate and heart' are entered into PubMed, suggesting that the issue of surrogate endpoints goes beyond the field of oncology, although the frequency of discussion varies (Figure 1; note different y-axis scales for oncology and cardiology).The goal of the present paper is to discuss the main issues surrounding surrogate endpoints from a clinician's point of view, using as an example surrogate endpoints of overall survival (OS) in advanced colorectal cancer (ACC). 相似文献
88.
89.
Pascal Steiner Enrico Gnecco Tobin Filleter Nitya Nand Gosvami Sabine Maier Ernst Meyer Roland Bennewitz 《Tribology Letters》2010,39(3):321-327
We review recent friction measurements on ordered superstructures performed by atomic force microscopy. In particular, we
consider ultrathin KBr films on NaCl(001) and Cu(001) surfaces, single and bilayer graphene on SiC(0001), and the herringbone
reconstruction of Au(111). Atomically resolved friction images of these systems show periodic features spanning across several
unit cells. Although the physical mechanisms responsible for the formation of these superstructures are quite different, the
experimental results can be interpreted within the same phenomenological framework. A comparison between experiments and modeling
shows that, in the cases of KBr films on NaCl(001) and of graphene films, the tip-surface interaction is well described by
a potential with the periodicity of the substrate which is modulated or, respectively, superimposed with a potential with
the symmetry of the superstructure. 相似文献
90.
Pascal Suer Jan-Erik Lindqvist Paul Frogner-Kockum 《The Science of the total environment》2009,407(18):5110-5118
Reuse of industrial aggregates is still hindered by concern for their long-term properties. This paper proposes a laboratory method for accelerated ageing of steel slag, to predict environmental and technical properties, starting from fresh slag. Ageing processes in a 10-year old asphalt road with steel slag of electric arc furnace (EAF) type in the subbase were identified by scanning electron microscopy (SEM) and leaching tests. Samples from the road centre and the pavement edge were compared with each other and with samples of fresh slag. It was found that slag from the pavement edge showed traces of carbonation and leaching processes, whereas the road centre material was nearly identical to fresh slag, in spite of an accessible particle structure. Batches of moisturized road centre material exposed to oxygen, nitrogen or carbon dioxide (CO2) were used for accelerated ageing. Time (7-14 days), temperature (20-40 °C) and initial slag moisture content (8-20%) were varied to achieve the carbonation (decrease in pH) and leaching that was observed in the pavement edge material. After ageing, water was added to assess leaching of metals and macroelements. 12% moisture, CO2 and seven days at 40 °C gave the lowest pH value. This also reproduced the observed ageing effect for Ca, Cu, Ba, Fe, Mn, Pb, Ca (decreased leaching) and for V, Si, and Al (increased leaching). However, ageing effects on SO4, DOC and Cr were not reproduced. 相似文献