全文获取类型
收费全文 | 78482篇 |
免费 | 5662篇 |
国内免费 | 1648篇 |
专业分类
电工技术 | 2660篇 |
技术理论 | 3篇 |
综合类 | 2303篇 |
化学工业 | 14904篇 |
金属工艺 | 3785篇 |
机械仪表 | 4895篇 |
建筑科学 | 3661篇 |
矿业工程 | 1038篇 |
能源动力 | 2757篇 |
轻工业 | 6005篇 |
水利工程 | 789篇 |
石油天然气 | 2036篇 |
武器工业 | 265篇 |
无线电 | 10913篇 |
一般工业技术 | 13843篇 |
冶金工业 | 5885篇 |
原子能技术 | 896篇 |
自动化技术 | 9154篇 |
出版年
2024年 | 133篇 |
2023年 | 1006篇 |
2022年 | 1163篇 |
2021年 | 2506篇 |
2020年 | 1939篇 |
2019年 | 1858篇 |
2018年 | 2242篇 |
2017年 | 2278篇 |
2016年 | 2447篇 |
2015年 | 2549篇 |
2014年 | 3418篇 |
2013年 | 4795篇 |
2012年 | 4828篇 |
2011年 | 5567篇 |
2010年 | 4441篇 |
2009年 | 4428篇 |
2008年 | 4263篇 |
2007年 | 3597篇 |
2006年 | 3449篇 |
2005年 | 3131篇 |
2004年 | 2449篇 |
2003年 | 2320篇 |
2002年 | 2228篇 |
2001年 | 1881篇 |
2000年 | 1891篇 |
1999年 | 1929篇 |
1998年 | 2562篇 |
1997年 | 1826篇 |
1996年 | 1538篇 |
1995年 | 1234篇 |
1994年 | 973篇 |
1993年 | 800篇 |
1992年 | 587篇 |
1991年 | 490篇 |
1990年 | 421篇 |
1989年 | 404篇 |
1988年 | 300篇 |
1987年 | 226篇 |
1986年 | 221篇 |
1985年 | 212篇 |
1984年 | 163篇 |
1983年 | 104篇 |
1982年 | 107篇 |
1981年 | 118篇 |
1980年 | 103篇 |
1979年 | 71篇 |
1978年 | 58篇 |
1977年 | 95篇 |
1976年 | 146篇 |
1975年 | 67篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
31.
32.
针对红岭铅锌矿分级充填骨料来源不足、地表废石堆积污染环境的情况,提出将该矿选厂产生的全尾砂和地表废石作为充填骨料的联合胶结充填方案。分别测试了全尾砂和地表废石的物理化学性质,验证了碎石和全尾砂作为联合充填骨料的可行性。通过充填配比试验,分析了不同配比全尾砂废石充填体强度特性,得出了最佳充填配比。结果表明,充填试块的强度随灰砂比减小而减小,随养护龄期增加呈增大趋势,随充填料浆质量浓度增大而增大,最佳配比为: 胶结充填灰砂比1∶8、普通充填灰砂比1∶12,全尾砂∶废石配比4∶6,质量浓度78%。根据研究结果,在红岭铅锌矿进行了全尾砂废石充填技术工业应用,证实该技术可行。 相似文献
33.
Guo-Yu Li Ya-Xin Zheng Fu-Zhou Sun Jian Huang Meng-Meng Lou Jing-Kai Gu Jin-Hui Wang 《International journal of molecular sciences》2015,16(9):22190-22204
This study aimed at investigating the possible mechanisms of hepatic protective activity of Cichorium intybus L. (chicory) in acute liver injury. Pathological observation, reactive oxygen species (ROS) detection and measurements of biochemical indexes on mouse models proved hepatic protective effect of Cichorium intybus L. Identification of active compounds in Cichorium intybus L. was executed through several methods including ultra performance liquid chromatography/time of flight mass spectrometry (UPLC-TOF-MS). Similarity ensemble approach (SEA) docking, molecular modeling, molecular docking, and molecular dynamics (MD) simulation were applied in this study to explore possible mechanisms of the hepato-protective potential of Cichorium intybus L. We then analyzed the chemical composition of Cichorium intybus L., and found their key targets. Furthermore, in vitro cytological examination and western blot were used for validating the efficacy of the selected compounds. In silico analysis and western blot together demonstrated that selected compound 10 in Cichorium intybus L. targeted Akt-1 in hepatocytes. Besides, compound 13 targeted both caspase-1 and Akt-1. These small compounds may ameliorate liver injury by acting on their targets, which are related to apoptosis or autophagy. The conclusions above may shed light on the complex molecular mechanisms of Cichorium intybus L. acting on hepatocytes and ameliorating liver injury. 相似文献
34.
Bacteria with antibiotic-resistant could seriously threaten to human health, increasing the treatment cost for infections and negatively affecting treatment outcomes. Stress adaptation is one possible mechanism for the acquisition or enhancement of antibiotic resistance in bacteria as a result of cross-protection. In this study, the effects of acid, salt, and cold stress on the antibiotic resistance of Salmonella Enteritidis, Listeria monocytogenes, and Escherichia coli O157:H7 were investigated using the disc diffusion method. For S. Enteritidis, acidic growth conditions increased resistance to ciprofloxacin and erythromycin (p < .05), and addition of 4% NaCl to growth media decreased resistance to chloramphenicol (p < .05). Irrespective of pH and the NaCl concentration of the growth medium, refrigerated E. coli O157:H7 showed increased resistance to amoxycillin, ciprofloxacin, gentamicin, streptomycin, and erythromycin (p < .05). Acid-adapted L. monocytogenes showed decreased the resistance to amoxycillin, ampicillin, chloramphenicol, ciprofloxacin, erythromycin, gentamicin, streptomycin, and tetracycline (p < .05). In conclusion, prolonged exposure of foodborne pathogens to acid, salt, and cold stress alters their antibiotic resistance. However, the effect of acid, salt, and cold stress on bacterial antibiotic resistance depend on both the bacterial species and the specific antibiotic. Therefore, multiple factors need to be considered for a foodborne antimicrobial resistant risk assessment. 相似文献
35.
Silicon - A total of six glass batches (WB100-WB50) based primarily on weathered basalt with successive addition of bypass cement dust (with the weight content 0–50%) were melted at... 相似文献
36.
37.
38.
Xiaohui Hu Li Cheng Yan Hong Zhaofeng Li Caiming Li Zhengbiao Gu 《International Journal of Food Science & Technology》2021,56(8):4149-4158
Incorporating high level of potato flour into wheat flour enhances nutritional values of bread but induces a series of problems that lead to the decline of the bread quality. To overcome the barrier, wheat gluten and carboxymethylcellulose (CMC) were added into potato–wheat composite flour to improve dough machinability and bread quality. The rheological properties, thermo-mechanical properties and microstructures of dough were investigated. The results showed that the interaction between gluten and CMC mitigated the discontinuity of gluten matrix and gluten protein aggregation caused by the addition of potato flour, which yielded a more branched and compact gluten network. The compact three-dimensional viscoelastic structure induced improvements of gas retention capacity and dough stability, making it mimic the machinability properties of wheat flour dough. Bread qualities were apparently improved with the combined use of 4% gluten and 6% CMC, of which specific volume increased by 42.86%, and simultaneously, hardness reduced by 75.93%. 相似文献
39.
In vivo Kinetic Biodistribution of Nano‐Sized Outer Membrane Vesicles Derived from Bacteria 下载免费PDF全文
Su Chul Jang Sae Rom Kim Yae Jin Yoon Kyong‐Su Park Ji Hyun Kim Jaewook Lee Oh Youn Kim Eun‐Jeong Choi Dae‐Kyum Kim Dong‐Sic Choi Yoon‐Keun Kim Jaesung Park Dolores Di Vizio Yong Song Gho 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(4):456-461
Evaluation of kinetic distribution and behaviors of nanoparticles in vivo provides crucial clues into their roles in living organisms. Extracellular vesicles are evolutionary conserved nanoparticles, known to play important biological functions in intercellular, inter‐species, and inter‐kingdom communication. In this study, the first kinetic analysis of the biodistribution of outer membrane vesicles (OMVs)—bacterial extracellular vesicles—with immune‐modulatory functions is performed. OMVs, injected intraperitoneally, spread to the whole mouse body and accumulate in the liver, lung, spleen, and kidney within 3 h of administration. As an early systemic inflammation response, increased levels of TNF‐α and IL‐6 are observed in serum and bronchoalveolar lavage fluid. In addition, the number of leukocytes and platelets in the blood is decreased. OMVs and cytokine concentrations, as well as body temperature are gradually decreased 6 h after OMV injection, in concomitance with the formation of eye exudates, and of an increase in ICAM‐1 levels in the lung. Following OMV elimination, most of the inflammatory signs are reverted, 12 h post‐injection. However, leukocytes in bronchoalveolar lavage fluid are increased as a late reaction. Taken together, these results suggest that OMVs are effective mediators of long distance communication in vivo. 相似文献
40.
Microsystem Technologies - A color-laser printing system consisting of a tandem laser scanning unit uses four laser diodes and a single polygonal mirror (PM) to expose light onto four... 相似文献