全文获取类型
收费全文 | 18398篇 |
免费 | 1966篇 |
国内免费 | 1027篇 |
专业分类
电工技术 | 1243篇 |
技术理论 | 3篇 |
综合类 | 1383篇 |
化学工业 | 2846篇 |
金属工艺 | 1065篇 |
机械仪表 | 1219篇 |
建筑科学 | 1662篇 |
矿业工程 | 501篇 |
能源动力 | 492篇 |
轻工业 | 1276篇 |
水利工程 | 318篇 |
石油天然气 | 925篇 |
武器工业 | 172篇 |
无线电 | 2192篇 |
一般工业技术 | 2141篇 |
冶金工业 | 968篇 |
原子能技术 | 196篇 |
自动化技术 | 2789篇 |
出版年
2024年 | 150篇 |
2023年 | 363篇 |
2022年 | 688篇 |
2021年 | 946篇 |
2020年 | 697篇 |
2019年 | 534篇 |
2018年 | 548篇 |
2017年 | 583篇 |
2016年 | 567篇 |
2015年 | 806篇 |
2014年 | 943篇 |
2013年 | 1025篇 |
2012年 | 1113篇 |
2011年 | 1139篇 |
2010年 | 1060篇 |
2009年 | 962篇 |
2008年 | 1036篇 |
2007年 | 958篇 |
2006年 | 933篇 |
2005年 | 864篇 |
2004年 | 704篇 |
2003年 | 528篇 |
2002年 | 536篇 |
2001年 | 467篇 |
2000年 | 455篇 |
1999年 | 449篇 |
1998年 | 367篇 |
1997年 | 350篇 |
1996年 | 304篇 |
1995年 | 250篇 |
1994年 | 211篇 |
1993年 | 193篇 |
1992年 | 130篇 |
1991年 | 92篇 |
1990年 | 87篇 |
1989年 | 80篇 |
1988年 | 51篇 |
1987年 | 36篇 |
1986年 | 35篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 18篇 |
1981年 | 9篇 |
1980年 | 24篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 13篇 |
1973年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A novel conjugated cationic polyfluorene containing aminated tetraphenylethene (ATPE) unit is developed as a sensitive and selective fluorescence probe for heparin detection based on the combination of aggregation-induced emissive property of the ATPE units and the FRET process from the blue-emissive polyfluorene segments to the yellow-emissive ATPE units. The addition of anionic heparin will lead to the formation of heparin/polymer complexes, and turn on the aggregation-induced yellow emission of the ATPE units. A good linear relationship is found between the yellow emission intensity of the ATPE units and the heparin concentrations with a limit of detection of 30 nM in aqueous buffer. 相似文献
992.
Taotao Zou Jing-Jing Zhang Bei Cao Ka-Chung Tong Chun-Nam Lok Chi-Ming Che 《Israel journal of chemistry》2016,56(9-10):825-833
Metal-based anticancer agents with non-DNA targets are anticipated for overcoming cisplatin resistance problems. Gold complexes are generally known to undergo ligand exchange or redox reactions with thiols, and hence, are potentially useful agents that could target thiol-containing enzymes, but not DNA. Recent studies have shown that deubiquitinases (DUBs), key enzymes regulating proteasome-related protein homeostasis, are potential anticancer targets of both gold(I) and gold(III) complexes. In this review, the current status of gold complexes as DUB inhibitors is discussed. In particular, auranofin and cyclometalated gold(III) complexes containing dithiocarbamate ligands (e.g., [(AuIII(C N)(DEDT)]+, HC N=2-phenylpyridine, DEDT=diethyldithiocarbamate) are highlighted as examples of DUB inhibitors. The mechanisms of their anticancer action, together with in vitro and/or in vivo antitumor potencies, are also explored. 相似文献
993.
L. K. Ji T. Xu J. M. Zhang H. T. Wang M. X. Tong R. H. Zhu G. S. Zhou 《Journal of Materials Engineering and Performance》2017,26(7):3104-3111
Tensile properties of the high-deformability dual-phase ferrite-bainite X70 pipeline steel have been investigated at room temperature under the strain rates of 2.5 × 10?5, 1.25 × 10?4, 2.5 × 10?3, and 1.25 × 10?2 s?1. The microstructures at different amount of plastic deformation were examined by using scanning and transmission electron microscopy. Generally, the ductility of typical body-centered cubic steels is reduced when its stain rate increases. However, we observed a different ductility dependence on strain rates in the dual-phase X70 pipeline steel. The uniform elongation (UEL%) and elongation to fracture (EL%) at the strain rate of 2.5 × 10?3 s?1 increase about 54 and 74%, respectively, compared to those at 2.5 × 10?5 s?1. The UEL% and EL% reach to their maximum at the strain rate of 2.5 × 10?3 s?1. This phenomenon was explained by the observed grain structures and dislocation configurations. Whether or not the ductility can be enhanced with increasing strain rates depends on the competition between the homogenization of plastic deformation among the microconstituents (ultra-fine ferrite grains, relatively coarse ferrite grains as well as bainite) and the progress of cracks formed as a consequence of localized inconsistent plastic deformation. 相似文献
994.
Yin Lairong Han Jianyou Mao Cong Huang Juan Yang Tong 《Journal of Mechanical Science and Technology》2012,26(10):3159-3167
An analytical method for synthesizing and selecting desired four-bar straight-line mechanisms based on solution regions is presented. Given two fixed pivots, the point position and direction of the target straight-line, an infinite number of mechanism solutions can be produced by employing this method, both in the general case and all three special cases. Unifying the straight-line direction and the displacement from the given point to the instant center into the same form with different angles as parameters, infinite mechanism solutions can be expressed with different solution region charts. The mechanism property graphs have been computed to enable the designers to find out the involved mechanism information more intuitively and avoid aimlessness in selecting optimal mechanisms. 相似文献
995.
Changes in the structure,digestibility and immunoreactivities of glycinin induced by the cross‐linking of microbial transglutaminase following heat denaturation
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Anshu Yang Jiaheng Xia Yuqing Gong Han Deng Zhihua Wu Xin Li Ping Tong Hongbing Chen 《International Journal of Food Science & Technology》2017,52(10):2265-2273
This study aimed to evaluate the effects of microbial transglutaminase (MTG)‐mediated modification on the structure, digestibility and immunoreactivities of glycinin. Glycinin was separated from soya bean and cross‐linked with MTG, and the sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) showed that the molecular weight of cross‐linked glycinin was higher than that of native glycinin. Individual MTG cross‐linking could maintain stable secondary structures and spatial structure. Sequential heat denaturation and MTG cross‐linking could promote the unfolding of protein structures and reduce their hydrophobicity. The digestibility of glycinin was decreased, and its immunoreactivities were increased because of MTG‐induced structural alteration, including primary and spatial structures. 相似文献
996.
Fang Wang Yu-Jie Zhang Yue Zhou Ya Li Tong Zhou Jie Zheng Jiao-Jiao Zhang Sha Li Dong-Ping Xu Hua-Bin Li 《International journal of molecular sciences》2016,17(3)
Nonalcoholic beverages are usually consumed accompanying alcoholic drinks, and their effects on alcohol metabolism are unclear in vivo. In this study, the effects of 20 nonalcoholic beverages on alcohol metabolism and liver injury caused by alcohol were evaluated in mice. Kunming mice were orally fed with alcohol (52%, v/v) and beverages. The concentrations of ethanol and acetaldehyde in blood as well as the activities of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) in liver were assessed to indicate alcohol metabolism. The levels of aspartate aminotransferase (AST) and alanine transaminase (ALT) in serum as well as the levels of malonaldehyde (MDA) and superoxide dismutase (SOD) in liver were measured to reflect the alcohol-induced liver injury. The results showed that the treatment of soda water, green tea and honey chrysanthemum tea could accelerate ethanol metabolism and prevent liver injuries caused by alcohol when companied with excessive alcohol drinking. They might be potential dietary supplements for the alleviation of harmful effects from excessive alcohol consumption. On the contrary, some beverages such as fresh orange juice and red bull are not advised to drink when companied with alcohol consumption due to their adverse effects on ethanol induced liver injury. 相似文献
997.
研究一类含参数的非线性四阶多点边值问题,当参数属于一定范围时,利用常数变易法求得与边值问题等价的函数,并对它进行上下界估计,同时利用锥不动点定理,证明该四阶边值问题正解的存在性. 相似文献
998.
A broadband circularly polarized patch antenna with suspended structure is proposed. The suspended patch has a bow‐tie structure and a gap‐coupled feed. By connecting a resistor load to another gap‐coupled feed port at the opposite position, a wide impedance and axial ratio (AR) bandwidths are obtained. The proposed design has a very simple antenna structure with an impedance bandwidth of 44.5% and a 3‐dB AR bandwidth of 33.8%, respectively. The results show that the bandwidth of the patch antenna is successfully broadened using the suspended configuration, gap‐coupled feed, and resistor loading. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:587–593, 2014. 相似文献
999.
在沿海地区软土地基工程建设中,大面积地坪的不均匀沉降一直是一个令人头痛的问题.以上海浦东国际机场西货运区3#货运站工程为例,介绍了真空预压法首次在单体面积超过9万m2的仓库项目工程中的使用,对真空预压的各个技术要点进行了阐述,在工程实践中取得了良好的成效,为相关工程积累了宝贵经验. 相似文献
1000.
Q. J. Tian P. Gong B. Xu X. Wang H. Guo Q. Tong 《International journal of remote sensing》2013,34(23):5123-5128
Relationships among average spectral reflectance measured in the visible and near infrared (VNIR) region (0.4-2.5 w m), dielectric constant measured in the microwave region (0.5-18 GHz) and chemical content of 34 sedimentary rock samples were measured. The natural logarithm of the average spectral reflectance and that of the imaginary part of the dielectric constant were negatively correlated ( 𝜌 =-0.60). The average spectral reflectance correlated negatively with Fe2O3 ( 𝜌 =-0.61), Al2O3 ( 𝜌 =-0.63), K2O ( 𝜌 =-0.60), TiO2 ( 𝜌 =-0.64), and P2O5 ( 𝜌 =-0.60). The average imaginary part of the dielectric constant correlated positively with Fe2O3 ( 𝜌 =0.76), K2O ( 𝜌 =0.62), and TiO2 ( 𝜌 =0.70). The average real part of the dielectric constant is highly correlated with the weight loss of the rocks due to burning (burnt loss) ( 𝜌 =0.92), SiO2 ( 𝜌 =-0.96), and CaO ( 𝜌 =0.91). 相似文献