全文获取类型
收费全文 | 11456篇 |
免费 | 989篇 |
国内免费 | 666篇 |
专业分类
电工技术 | 182篇 |
综合类 | 606篇 |
化学工业 | 4016篇 |
金属工艺 | 775篇 |
机械仪表 | 122篇 |
建筑科学 | 523篇 |
矿业工程 | 294篇 |
能源动力 | 294篇 |
轻工业 | 3101篇 |
水利工程 | 180篇 |
石油天然气 | 1168篇 |
武器工业 | 55篇 |
无线电 | 178篇 |
一般工业技术 | 767篇 |
冶金工业 | 522篇 |
原子能技术 | 185篇 |
自动化技术 | 143篇 |
出版年
2024年 | 64篇 |
2023年 | 199篇 |
2022年 | 429篇 |
2021年 | 457篇 |
2020年 | 416篇 |
2019年 | 350篇 |
2018年 | 332篇 |
2017年 | 384篇 |
2016年 | 451篇 |
2015年 | 431篇 |
2014年 | 640篇 |
2013年 | 671篇 |
2012年 | 956篇 |
2011年 | 808篇 |
2010年 | 581篇 |
2009年 | 643篇 |
2008年 | 436篇 |
2007年 | 682篇 |
2006年 | 647篇 |
2005年 | 513篇 |
2004年 | 512篇 |
2003年 | 456篇 |
2002年 | 382篇 |
2001年 | 316篇 |
2000年 | 259篇 |
1999年 | 212篇 |
1998年 | 179篇 |
1997年 | 122篇 |
1996年 | 109篇 |
1995年 | 87篇 |
1994年 | 76篇 |
1993年 | 55篇 |
1992年 | 54篇 |
1991年 | 34篇 |
1990年 | 44篇 |
1989年 | 36篇 |
1988年 | 12篇 |
1987年 | 19篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1975年 | 2篇 |
1959年 | 3篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
A set of poly[N‐oligo(ethylene oxide)yl 4‐vinylpyridinium tosylate] (P4VOEOOTs) has been prepared by spontaneous polymerization of 4‐vinylpyridine. This method gives a grafted polyelectrolyte having a positive charge on every backbone pyridinic moiety. The P4VP15Ts, P4VP164Ts, P4VP350Ts and P4VP750Ts aqueous solution conductivities were determined in the concentration range from 6 × 10?4 to 10?2 M at 25 °C. The variation of the conductivity versus concentration of the investigated system exhibits typical polyelectrolyte behaviour. The polyelectrolyte mobility was found to be dependent on the oligo(ethylene oxide) (OEO) side‐chain length. Manning's rod‐like model fails to describe these results. A simple steric effect is proposed to explain the influence of the OEO length. Copyright © 2003 Society of Chemical Industry 相似文献
2.
通过认真学习《细节决定成败》,结合井矿盐开采的实际,分别以生产过程中的三个细节为主,讨论了在采输卤生产技术控制中的细节的重要性。 相似文献
3.
We have developed new photopolymers that have superior waterproof properties and that can easily interact with polyfunctional acrylate compounds, thus serving as hydrophobic photocrosslinking reagents. Acryloylmorpholine monomers whose homopolymers were less moisture absorbing than the usual water‐soluble polymers but were still water soluble to a good degree, were copolymerized with other acryloyl monomers. We then introduced the photosensitive (meth)acryloyl group to side chains of the resulting polymers. Among six copolymers examined, the copolymers composed of acryloyl morpholine, hydroxyethyl acrylate, ethyl, or methyl methacrylate, and methacryloyl isocyanate were found to have nicely balanced hydrophilicity and waterproof properties, in addition to good compatibility with hydrophobic photocrosslinking reagents. The composite polymers thus obtained were confirmed to be promising photopolymers usable even in a highly humid environment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 684–692, 2003 相似文献
4.
高抗挤厚壁套管的性能及应用效果评价 总被引:1,自引:1,他引:0
中原油田套管损坏的主要原因是现有套管强度不够,无法抵抗盐膏层段的巨大外挤力。开发了TP130TT型高抗挤厚壁套管,其强度能很好地抵抗盐膏层巨大外挤力。实验室试验表明,各项性能指标达到了设计要求,现场使用取得了很好的效果,解决了中原油田盐膏层段套管强度不足的难题。 相似文献
5.
6.
真空制盐蒸发结晶器的设计与实践 总被引:2,自引:0,他引:2
真空蒸发制盐外热式强制逆循环轴向出料蒸发结晶器,经多个厂家生产应用实践证明是成功的,具有生命力的。这种新型结构,作为一项新技术新设备应加强研究,总结提高,推广应用。不断完善。文章从流体力学、结晶机理角度要求,到具体工程设计参数和材质选用。论述了该罐的特点。 相似文献
7.
Vjacheslav V. Zuev 《Journal of Polymer Research》2008,15(5):351-356
Functionalized polyanilines containing biphenyl, terphenyl, carbazole, anthracene, and 4-n-hexylphenyl moieties were synthesized though the reaction of polyaniline in emeraldine base form with sodium salt of corresponding
vinylketoaromatics with quantitative yields. Polymers were characterized with Fourier transform infrared spectroscopy, proton
nuclear magnetic resonance spectroscopy, and thermogravimetry. The emission characteristics of these polymers in N-methyl-2-pyrrolidone solution were examined. The functionalized polyanilines exhibited an intense green emission. 相似文献
8.
钻一口通过主采盐层的水平井与已完成的直井对接,形成连通井(形如“U”字),一口井注水溶解盐/芒硝矿,另一口井采出卤水,这是盐化工业对钻井提出的要求。针对水平对接盐井井身轨迹设计、着陆段、水平段的轨迹控制和连通技术,介绍了水平段侧钻时的钻井液技术。 相似文献
9.
Gelation Properties of Ovalbumin as Affected by Fatty Acid Salts 总被引:2,自引:0,他引:2
NAOKO YUNO-OHTA HIROKO TORYU TAKAHIKO HIGASA HIDEO MAEDA MITSUKO OKADA HIROYUKI OHTA 《Journal of food science》1996,61(5):906-910
The physicochemical properties of heat-induced ovalbumin (OVA) gels containing fatty acid salts (FAS) were investigated. Water-holding ability and transparency markedly increased in the presence of sodium caprate or sodium laurate. At 9% of the protein concentration transparent and hard gels formed; at 7%, transparent and soft gels formed. Scanning electron microscopy showed that the transparent gels had a more homogeneous structure than turbid gels without FAS. Differential scanning calorimetry indicated that denaturation temperature of OVA was decreased and the peaks became broader after addition of FAS. 相似文献
10.
In this study a thermodynamic model for the phase behavior of aqueous salt+polymer solutions is developed. The model is based on the solution theory of Hill, which included scaling laws for the polymer molecular mass dependence and Pitzer–Debye–Hückel theory. This model was tested for systems composed of two different molecular mass of polyethylene glycols (PEG) and five different inorganic salts. All the model parameters were determined from independent measurements. The agreement between the experimental and predicted phase diagrams by this model is good. 相似文献