全文获取类型
收费全文 | 41810篇 |
免费 | 4982篇 |
国内免费 | 2281篇 |
专业分类
电工技术 | 11272篇 |
技术理论 | 2篇 |
综合类 | 3258篇 |
化学工业 | 3121篇 |
金属工艺 | 1631篇 |
机械仪表 | 1325篇 |
建筑科学 | 5660篇 |
矿业工程 | 2122篇 |
能源动力 | 951篇 |
轻工业 | 1337篇 |
水利工程 | 2079篇 |
石油天然气 | 1894篇 |
武器工业 | 347篇 |
无线电 | 3554篇 |
一般工业技术 | 2028篇 |
冶金工业 | 1362篇 |
原子能技术 | 426篇 |
自动化技术 | 6704篇 |
出版年
2024年 | 129篇 |
2023年 | 387篇 |
2022年 | 986篇 |
2021年 | 1219篇 |
2020年 | 1177篇 |
2019年 | 889篇 |
2018年 | 865篇 |
2017年 | 1140篇 |
2016年 | 1281篇 |
2015年 | 1590篇 |
2014年 | 3199篇 |
2013年 | 2266篇 |
2012年 | 3410篇 |
2011年 | 3644篇 |
2010年 | 2827篇 |
2009年 | 2840篇 |
2008年 | 2651篇 |
2007年 | 3122篇 |
2006年 | 2828篇 |
2005年 | 2343篇 |
2004年 | 1891篇 |
2003年 | 1806篇 |
2002年 | 1447篇 |
2001年 | 1255篇 |
2000年 | 1015篇 |
1999年 | 759篇 |
1998年 | 486篇 |
1997年 | 364篇 |
1996年 | 284篇 |
1995年 | 268篇 |
1994年 | 170篇 |
1993年 | 115篇 |
1992年 | 82篇 |
1991年 | 57篇 |
1990年 | 44篇 |
1989年 | 39篇 |
1988年 | 44篇 |
1987年 | 18篇 |
1986年 | 22篇 |
1985年 | 20篇 |
1984年 | 30篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1965年 | 4篇 |
1964年 | 3篇 |
1963年 | 4篇 |
1961年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Ping-Chi Hsu Jia-Ying Jhong Li-Ping Huang Kuo-Hsin Lee Hsin-Pao Chen Yue-Leon Guo 《International journal of molecular sciences》2021,22(8)
Di(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in the manufacture of polyvinylchloride plastics and has been associated with concerns regarding male reproductive toxicity. In this study, we hypothesized that maternal exposure to DEHP induces transgenerational inheritance of adult-onset adverse reproductive outcomes through the male germline in the F1, F2, and F3 generations of male offspring. Pregnant rats were treated with 5 or 500 mg of DEHP/kg/day through gavage from gestation day 0 to birth. The offspring body weight, anogenital distance (AGD), anogenital index (AGI), sperm count, motility, and DNA fragmentation index (DFI) were measured for all generations. Methyl-CpG binding domain sequencing was performed to analyze sperm DNA methylation status in the F3. DEHP exposure at 500 mg/kg affected AGD, AGI, sperm count, mean DFI, and %DFI in the F1; AGD, sperm count, and mean DFI in the F2; and AGD, AGI, mean DFI, and %DFI in the F3. DEHP exposure at 5 mg/kg affected AGD, AGI, sperm count, and %DFI in the F1; sperm count in the F2; and AGD and AGI in F3. Compared with the control group, 15 and 45 differentially hypermethylated genes were identified in the groups administered 5 mg/kg and 500 mg/kg DEHP, respectively. Moreover, 130 and 6 differentially hypomethylated genes were observed in the groups administered 5 mg/kg and 500 mg/kg DEHP. Overall, these results demonstrated that prenatal exposure to DEHP caused transgenerational epigenetic effects, which may explain the observed phenotypic changes in the male reproductive system. 相似文献
2.
3.
冯鹏一 《信息通信技术与政策》2020,(1):12-15
以电信用户入网协议为切入点,电信用户的携号转网行为应受到《合同法》《消费者权益保护法》等私法规范的保护与限制。该行为引起的格式条款解释、合同终止、违约责任、损失赔偿等问题,不能仅靠《电信条例》等公法规范来调整。应当积极引导广大消费者用户以私法领域相关规定为依据,转变争议解决思维,拓宽纠纷处理途径,合理选择维权手段,以保护自身合法民事权益,与行业监管部门共同推动电信行业有序发展。 相似文献
4.
伏彩萍 《有色金属(冶炼部分)》2020,(6):66-69
针对现有柠檬酸铋制备工艺合成时间长、能耗高、产品纯度不高等不足,介绍了一种常温下制备柠檬酸铋的新工艺。新工艺制备时间短,制备的柠檬酸铋产品质量好,合成过程产生的废水可循环利用,废气经碱液循环吸收可生产硝酸钠副产品。 相似文献
5.
6.
This article presents a new method for pairing devices securely. The commitment-based authentication uses a fuzzy secret that the devices only know approximately. Its novel feature is time-based opening of commitments in a single round. We also introduce a new source for the fuzzy secret: synchronized drawing with two fingers of the same hand on two touch screens or surfaces. The drawings are encoded as strings and compared with an edit-distance metric. A prototype implementation of this surprisingly simple and natural pairing mechanism shows that it accurately differentiates between true positives and man-in-the-middle attackers. 相似文献
7.
In vivo Kinetic Biodistribution of Nano‐Sized Outer Membrane Vesicles Derived from Bacteria
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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
8.
文章通过对黑龙江省高效节水现状,存在问题的分析,结合黑龙江省高效节水发展的支撑能力,阐述黑龙江省节水增粮目标、任务及总体布局,为黑龙江省2012—2015年节水增粮实施提供依据。 相似文献
9.
This paper deals with the application of wavelet transforms for the detection, classification and location of faults on transmission lines. A Global Positioning System clock is used to synchronize sampling of voltage and current signals at both the ends of the transmission line. The detail coefficients of current signals of both the ends are utilized to calculate fault indices. These fault indices are compared with threshold values to detect and classify the faults. Artificial Neural Networks are employed to locate the fault, which make use of approximate decompositions of the voltages and currents of local end. The proposed algorithm is tested successfully for different locations and types of faults. 相似文献
10.
从电焊机自身电气特点及建筑工地工作环境入手,探讨电焊机安全技术的实施方法。分析电焊机安全隐患及事故的分类以及电焊机在使用过程中产生危险的原因。介绍电焊机在安装以及作业过程中的安全措施。 相似文献