全文获取类型
收费全文 | 21044篇 |
免费 | 1690篇 |
国内免费 | 883篇 |
专业分类
电工技术 | 1085篇 |
综合类 | 1383篇 |
化学工业 | 3647篇 |
金属工艺 | 1437篇 |
机械仪表 | 1200篇 |
建筑科学 | 1560篇 |
矿业工程 | 775篇 |
能源动力 | 492篇 |
轻工业 | 1356篇 |
水利工程 | 367篇 |
石油天然气 | 1532篇 |
武器工业 | 201篇 |
无线电 | 2179篇 |
一般工业技术 | 2764篇 |
冶金工业 | 1156篇 |
原子能技术 | 204篇 |
自动化技术 | 2279篇 |
出版年
2024年 | 109篇 |
2023年 | 362篇 |
2022年 | 656篇 |
2021年 | 897篇 |
2020年 | 706篇 |
2019年 | 591篇 |
2018年 | 614篇 |
2017年 | 718篇 |
2016年 | 605篇 |
2015年 | 868篇 |
2014年 | 1077篇 |
2013年 | 1191篇 |
2012年 | 1281篇 |
2011年 | 1480篇 |
2010年 | 1252篇 |
2009年 | 1215篇 |
2008年 | 1103篇 |
2007年 | 1196篇 |
2006年 | 1156篇 |
2005年 | 986篇 |
2004年 | 619篇 |
2003年 | 552篇 |
2002年 | 554篇 |
2001年 | 474篇 |
2000年 | 479篇 |
1999年 | 545篇 |
1998年 | 415篇 |
1997年 | 379篇 |
1996年 | 324篇 |
1995年 | 296篇 |
1994年 | 251篇 |
1993年 | 172篇 |
1992年 | 132篇 |
1991年 | 85篇 |
1990年 | 63篇 |
1989年 | 50篇 |
1988年 | 56篇 |
1987年 | 32篇 |
1986年 | 22篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
Application of artificial neural network to predict the change of inosine monophosphate for lightly salted silver carp (hypophthalmichthys molitrix) during thermal treatment and storage
下载免费PDF全文
![点击此处可从《Journal of Food Processing and Preservation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
994.
Passenger thermal comfort and behavior: a field investigation in commercial aircraft cabins
下载免费PDF全文
![点击此处可从《Indoor air》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Passengers' behavioral adjustments warrant greater attention in thermal comfort research in aircraft cabins. Thus, a field investigation on 10 commercial aircrafts was conducted. Environment measurements were made and a questionnaire survey was performed. In the questionnaire, passengers were asked to evaluate their thermal comfort and record their adjustments regarding the usage of blankets and ventilation nozzles. The results indicate that behavioral adjustments in the cabin and the use of blankets or nozzle adjustments were employed by 2/3 of the passengers. However, the thermal comfort evaluations by these passengers were not as good as the evaluations by passengers who did not perform any adjustments. Possible causes such as differences in metabolic rate, clothing insulation and radiation asymmetry are discussed. The individual difference seems to be the most probable contributor, suggesting possibly that passengers who made adjustments had a narrower acceptance threshold or a higher expectancy regarding the cabin environment. Local thermal comfort was closely related to the adjustments and significantly influenced overall thermal comfort. Frequent flying was associated with lower ratings for the cabin environment. 相似文献
995.
介绍蜂窝式管状精密过滤装置的结构、过滤原理及滤芯缠绕装置的结构和工作原理,为减少外购辅料、节省资金开辟了一条途径。 相似文献
996.
Yewei Xu Xiangwang Cui Fanghua Zhu Xuan Luo Qiang Yin Lin Zhang 《Polymer International》2014,63(3):537-545
Six new bis(benzimidazolyl) monomers containing ether, sulfonyl and ketone groups were synthesized efficiently. A series of poly(N‐arylenebenzimidazole)s were prepared using an aromatic nucleophilic displacement reaction that removed the N–H sites from the novel bis(benzimidazolyl) derivatives with activated aromatic difluorides in sulfolane. The reaction was carried out at 210 °C in the presence of anhydrous potassium carbonate. All resulting polymers showed essentially amorphous patterns. This was consistent with the calculated results. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>240 °C), good thermostability and high decomposition temperatures (>400 °C). These novel polymers also showed easy solubility. © 2013 Society of Chemical Industry 相似文献
997.
Yu-liang Shi Yu Chen Zhong-min Zhou Li-zhen Cui 《Journal of Signal Processing Systems》2017,89(1):27-39
Nowadays big data security plays a major issue in cloud computing. Chunk-confusion-based privacy protection mechanism (CCPPM) protects the privacy of the tenants in plaintext. But both multi-tenant applications’ data and tenants’ privacy requirements are dynamically changing, which will have a great effect on the underlying storage model of cloud data. Moreover, the tenants’ business processing will change the data distribution and destroy the distribution balance of privacy data, which makes the data stored in the cloud face the risk of leakage of privacy. Therefore, the paper proposed a privacy protection evaluation mechanism for dynamic data based on CCPPM. The paper firstly introduces three kinds of the privacy leakages due to unbalanced data under the CCPPM, and analyzes two methods used for attacking. Aiming at the privacy leakages and the attack methods, we proposed a dynamic data processing algorithm to record the tenants’ operation sequence and set up the corresponding evaluation formula. Next, we evaluated the effect of privacy protection from two aspects of simple attack and background-knowledge-based attack, and used the data distribution similarity privacy preserving dynamic evaluation algorithm presented in this paper to obtain the measurement results of privacy leakages. Finally, according to the evaluation results, the defense strategies are given to prevent data privacy leakages. The experimental evaluation proves that rationality of dynamic the evaluation mechanism proposed in this paper has better feasibility and practicality for big data privacy protection. 相似文献
998.
This article reviews the recently developed tough, self-recovery, and self-healing polyampholyte hydrogels. Polyampholyte hydrogels are synthesized using one-step radical copolymerization of cationic and anionic monomers with equal charges at high monomer concentration. The random copolymerization process makes the ionic monomers randomly distributing along the backbones, resulting in the formation of ionic bonds with a wide strength distribution via inter and intra chain complexation in the polymer network, weak bond and strong bonds. The strong bonds serve as permanent cross-linking, integrating the hydrogels to impart the elastic behavior, while the weak bonds can break upon the loading, dissipating energy to give the toughness, and re-form again after unloading to enable the self-recovery behavior. Accordingly, polyampholyte hydrogels have condensed polymers in water (ca 40?50 wt %). They are strongly viscoelastic and have a high toughness (fracture energy of 4000 J/m2), a wide range of tuning modulus (0.01 to 8 MPa), 100% self-recovery, and a high self-healing efficiency after cutting. 相似文献
999.
Cui Hu Zhan Wu Hao Tang Li-Juan Tang Ru-Qin Yu Jian-Hui Jiang 《International journal of molecular sciences》2014,15(4):5221-5232
Methods for the detection of specific interactions between diverse proteins and various small-molecule ligands are of significant importance in understanding the mechanisms of many critical physiological processes of organisms. The techniques also represent a major avenue to drug screening, molecular diagnostics, and public safety monitoring. Terminal protection assay of small molecule-linked DNA is a demonstrated novel methodology which has exhibited great potential for the development of simple, sensitive, specific and high-throughput methods for the detection of small molecule–protein interactions. Herein, we review the basic principle of terminal protection assay, the development of associated methods, and the signal amplification strategies adopted for performance improving in small molecule–protein interaction assay. 相似文献
1000.
Huiyang Liu Qin Wang Guangxia Shen Chunlei Zhang Chao Li Weihang Ji Chun Wang Daxiang Cui 《Nanoscale research letters》2014,9(1):397
Carbon dots exhibit great potential in applications such as molecular imaging and in vivo molecular tracking. However, how to enhance fluorescence intensity of carbon dots has become a great challenge. Herein, we report for the first time a new strategy to synthesize fluorescent carbon dots (C-dots) with high quantum yields by using ribonuclease A (RNase A) as a biomolecular templating agent under microwave irradiation. The synthesized RNase A-conjugated carbon dots (RNase A@C-dots) exhibited quantum yields of 24.20%. The fluorescent color of the RNase A@C-dots can easily be adjusted by varying the microwave reaction time and microwave power. Moreover, the emission wavelength and intensity of RNase A@C-dots displayed a marked excitation wavelength-dependent character. As the excitation wavelength alters from 300 to 500 nm, the photoluminescence (PL) peak exhibits gradually redshifts from 450 to 550 nm, and the intensity reaches its maximum at an excitation wavelength of 380 nm. Its Stokes shift is about 80 nm. Notably, the PL intensity is gradually decreasing as the pH increases, almost linearly dependent, and it reaches the maximum at a pH = 2 condition; the emission peaks also show clearly a redshift, which may be caused by the high activity and perfective dispersion of RNase A in a lower pH solution. In high pH solution, RNase A tends to form RNase A warped carbon dot nanoclusters. Cell imaging confirmed that the RNase A@C-dots could enter into the cytoplasm through cell endocytosis. 3D confocal imaging and transmission electron microscopy observation confirmed partial RNase A@C-dots located inside the nucleus. MTT and real-time cell electronic sensing (RT-CES) analysis showed that the RNase A@C-dots could effectively inhibit the growth of MGC-803 cells. Intra-tumor injection test of RNase A@C-dots showed that RNase A@C-dots could be used for imaging in vivo gastric cancer cells. In conclusion, the as-prepared RNase A@C-dots are suitable for simultaneous therapy and in vivo fluorescence imaging of nude mice loaded with gastric cancer or other tumors. 相似文献