全文获取类型
收费全文 | 11397篇 |
免费 | 1173篇 |
国内免费 | 791篇 |
专业分类
电工技术 | 170篇 |
综合类 | 1025篇 |
化学工业 | 742篇 |
金属工艺 | 162篇 |
机械仪表 | 445篇 |
建筑科学 | 362篇 |
矿业工程 | 97篇 |
能源动力 | 48篇 |
轻工业 | 2532篇 |
水利工程 | 18篇 |
石油天然气 | 64篇 |
武器工业 | 109篇 |
无线电 | 1161篇 |
一般工业技术 | 4145篇 |
冶金工业 | 185篇 |
原子能技术 | 12篇 |
自动化技术 | 2084篇 |
出版年
2024年 | 128篇 |
2023年 | 304篇 |
2022年 | 417篇 |
2021年 | 543篇 |
2020年 | 520篇 |
2019年 | 466篇 |
2018年 | 443篇 |
2017年 | 514篇 |
2016年 | 449篇 |
2015年 | 424篇 |
2014年 | 716篇 |
2013年 | 805篇 |
2012年 | 942篇 |
2011年 | 880篇 |
2010年 | 635篇 |
2009年 | 741篇 |
2008年 | 511篇 |
2007年 | 740篇 |
2006年 | 666篇 |
2005年 | 501篇 |
2004年 | 461篇 |
2003年 | 312篇 |
2002年 | 247篇 |
2001年 | 167篇 |
2000年 | 122篇 |
1999年 | 118篇 |
1998年 | 78篇 |
1997年 | 62篇 |
1996年 | 59篇 |
1995年 | 48篇 |
1994年 | 54篇 |
1993年 | 55篇 |
1992年 | 65篇 |
1991年 | 47篇 |
1990年 | 39篇 |
1989年 | 39篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1962年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Aluminium foil is an important material in laminates and has wide application in food packaging. Its barrier function against the migration of moisture, oxygen and other gases, and volatile aroma, as well as against the impact of light is generally higher than any plastic laminate material. Therefore, aluminium foil is used in the laminates when insufficient barrier properties are the limiting factor for shelf-life stability of food. The barrier properties of aluminium-coated plastic laminates, which can offer an alternative to aluminium foil laminates, are somewhat less efficient. The use of aluminium foil in rigid, semirigid, and flexible package for in-pack thermal processing allows the selection of package geometries that ensure rapid heating and minimum heat damage during processing. On the tightness of packages, the mechanical stability and quality of sealing is of particular importance. The chemical stability of aluminium foil in contact with food depends on the composition of the food items. With present toxicological knowledge, the use of aluminium in packaging material is considered to be safe, and inner-coating of the foil is recommended in specific cases. 相似文献
993.
建立了固相萃取(SPE)净化,超高效液相色谱串联三重四极杆质谱法(UPLC-MS/MS)同时检测食品接触纸包装材料中8种异噻唑啉酮类和氯酚类杀菌防腐剂(MI、CMI、BIT、2,4-DCP、2,4,6-TCP、2,3,4,6-TCP、PCP和OPP)的分析方法。样品经甲醇超声提取,HLB固相萃取小柱净化,以甲醇-水为流动相在Phenomenex kinetex C18色谱柱(100 mm×3.0 mm,2.6μm)上梯度洗脱分离,在电喷雾正、负离子分段扫描和多反应监测(MRM)模式下检测,以保留时间和特征离子对定性,外标法定量。结果表明,8种待测物在2.0~400μg/L范围内线性关系良好;方法定量限(S/N=10)在10μg/kg~30μg/kg之间;添加水平为10~300μg/kg时,平均回收率在80.3%~107%之间;相对标准偏差(RSD,n=6)为3.5%~9.3%。 相似文献
994.
V. Venugopal F. Shahidi Dr. Tung‐Ching Lee 《Critical reviews in food science and nutrition》1995,35(5):431-453
Fish is a rich source of easily digestible protein that also provides polyunsaturated fatty acids, vitamins, and minerals for human nutrition. Nonetheless, a large proportion of total landed fish remains unused due to inherent problems related to unattractive color, flavor, texture, small size, and high fat content. Most of these underutilized fish belong to the abundantly available pelagic species, which are landed as bycatch, and some are unconventional species such as krill. Although some species are used industrially for fish meal manufacture, a need for their conservation and utilization for human consumption has been recognized in order to prevent post‐harvest fishery losses. Recovery of flesh by mechanical deboning and development of value‐added products are probably the most promising approaches. This article discusses various possibilities for product development using mince from low‐cost fishery resources. These include surimi and surimi‐based products, sausages, fermented products, protein concentrates and hydrolysates, extruded products, and biotechnological possibilities. The dual advantages of this approach, namely, finding ways for better utilization of low‐value fish species and providing protein‐rich convenience foods, have been pointed out. However, the key to the success of this approach depends largely on the market strategies utilized. 相似文献
995.
对桶装方便面静电封合技术进行建模分析研究。根据桶装方便面防潮包装机工作过程分析静电封合技术的工作原理,提出静电封合技术的电荷积聚数学模型和静电力数学模型,并研究影响静电封合效果的主要影响因素。研究薄膜纵缝静电封合失效的原因,确定薄膜静电力衰减规律,建立塑料薄膜静电力衰减规律的数学模型。 相似文献
996.
ABSTRACT: Quality changes during 3 wk of refrigerated storage (1.3 °C) were studied on pre -rigor filleted farmed Atlantic cod packed in modified atmosphere (MAP, 60% CO2 and 40% O2 ) or vacuum. The packages of MAP contained either a CO2 emitter and low gas volume to product volume (g/p ratio) of 1.3, or a 3.9 g/p ratio and no emitter. The CO2 level remained stable or increased in the packages with CO2 emitter, whereas the CO2 level in the packages with no CO2 emitter decreased to 40% after 4 d of refrigerated storage. High levels of oxygen in the gas mixture prevented formation of trimethyl amine (TMA) during storage of the MA-packed fish, whereas the TMA content increased significantly after 10-d storage in vacuum. MA-packed samples had the highest values of 1-penten-3-ol. Sensory scores of sour, sulfur, and pungent odors were significantly higher for vacuum-packed cod compared to the 2 MA-packaging methods measured 14 d after slaughtering. No differences in sensory scores were observed between the 2 methods of MAP, and shelf life of these samples seemed to be 14 to 21 d. Cod samples packaged in vacuum packages had higher pH values compared to ordinary MAP and packages containing a CO2 emitter. Bacterial growth was inhibited by MAP and resulted at the end of the storage period in dominance of Carnobacterium and some Photobacterium . In MA packages with high O2 levels the Photobacterium was inhibited. It is concluded that CO2 emitters are well suited for reduction of transport volume for MA-packaged farmed cod. 相似文献
997.
Combined Application of Antibrowning,Heat Treatment and Modified‐Atmosphere Packaging to Extend the Shelf Life of Fresh‐Cut Lotus Root
下载免费PDF全文
![点击此处可从《Journal of food science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jihye Son Jeong‐Eun Hyun Jo‐Won Lee Sun‐Young Lee BoKyung Moon 《Journal of food science》2015,80(6):C1178-C1187
This work aimed to determine the effects of different concentrations of antibrowning treatments (that is, distilled water [DW], 1% ascorbic acid [AA], 0.5% chamomile [CM], and 1% AA + 0.5% CM) and heat‐treatment (55 °C for 45 s) combined with packaging under 4 different modified‐atmosphere gas compositions (that is, air, vacuum, 100% CO2, 50% CO2/50% N2) on the quality and microbiological characteristics of fresh‐cut lotus root. The quality characteristics (that is, color, weight loss, texture, pH, polyphenoloxidase activity, and total phenolic content) of the AA + CM‐dipped sample in 100% CO2 packaging were maintained significantly better than those of the other samples (P < 0.05). The microbiological counts observed in the DW‐dipped sample during storage were higher than those of the AA, CM, and AA + CM samples, and heat‐treatment retarded the microbiological deterioration of fresh‐cut lotus root. Therefore, the results revealed that dipping in an antibrowning treatment (AA + CM), and 100% CO2 MAP with heat treatment effectively extend the shelf life of fresh‐cut lotus root to 21 d at 5 °C. 相似文献
998.
开发了一种基于电镀铜锡合金薄膜的绝压气压传感器圆片级气密封装技术以降低常规的基于阳极键合气密封装技术的成本及难度。通过实验确定了铜锡合金薄膜的电镀参数,实现了结构参数为:Cr/Cu/Sn(30nm/4μm/4μm)的铜锡合金薄膜;通过共晶键合实验确定圆片级气密封装的参数,进行了基于铜锡材料的气密封装温度实验。通过比较各种不同温度下气密封装的结果,确定了完成圆片级气密封装的条件为:静态压力0.02 MPa,加热温度280°,保持20min。最后,对气密封装效果进行X-射线衍射谱(XRD)、X射线分析、剪切力以及氦气泄露分析等实验研究。XRD分析显示:在键合界面出现了Cu3Sn相,证明形成了很好的键合;X射线分析表明封装面无明显孔洞;剪切力分析给出平均键合强度为9.32 MPa,氦气泄露分析则显示泄露很小。得到的结果表明:基于电镀铜锡合金薄膜可以很好地实现绝压气压传感器的圆片级气密封装。 相似文献
999.
Techniques to measure sorption and migration between small molecules and packaging. A critical review
下载免费PDF全文
![点击此处可从《Journal of the science of food and agriculture》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ashish A Kadam Thomas Karbowiak Andrée Voilley Frédéric Debeaufort 《Journal of the science of food and agriculture》2015,95(7):1395-1407
The mass transfer parameters diffusion and sorption in food and packaging or between them are the key parameters for assessing a food product's shelf‐life in reference to consumer safety. This has become of paramount importance owing to the legislations set by the regulated markets. The technical capabilities that can be exploited for analyzing product–package interactions have been growing rapidly. Different techniques categorized according to the state of the diffusant (gas or liquid) in contact with the packaging material are emphasized in this review. Depending on the diffusant and on the analytical question under review, the different ways to study sorption and/or migration are presented and compared. Some examples have been suggested to reach the best possible choice, consisting of a single technique or a combination of different approaches. © 2014 Society of Chemical Industry 相似文献
1000.
为了进一步提高真空包装机的生产效率,打破现有机型的框框,全新地设计了XZD─500/2S旋转式真空包装机,填补了我国包装机的空白。本文从总体设计到机械传动、气路及工作台、箱体尺寸的确定都作了详细的说明与介绍。 相似文献