全文获取类型
收费全文 | 529篇 |
免费 | 28篇 |
出版年
2022年 | 5篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 21篇 |
2015年 | 29篇 |
2014年 | 40篇 |
2013年 | 38篇 |
2012年 | 50篇 |
2011年 | 51篇 |
2010年 | 26篇 |
2009年 | 27篇 |
2008年 | 35篇 |
2007年 | 29篇 |
2006年 | 20篇 |
2005年 | 26篇 |
2004年 | 48篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有557条查询结果,搜索用时 191 毫秒
551.
Recently, the leak of domestic core technology of major business in Korea and the subsequent damage, has been increasing every year. Financial losses due to this leak are estimated to be about 220 trillion, which is equivalent to the gross budget of Korea Besides. Currently, the paradigm of industrial security has been changed from simple installation of security equipment to efficient management and control market. Leakage of internal material is able to be prevented, blocked and tracking afterward innovatively through enterprise risk management and security control by fusion of physical security system (entrance control system, vision security system etc.) and IT integrated security control system. It can be possible to setup systematical converging security control process in short term by achieving an effect to running expert organization without additional investment for current physical security and IT security personnel, and it is needed to firmly setup the acquisition and integrated control of IT security and physical security, connected tracking control when security issue is happened, definition for terms of information leakage and security violation and real-time observation, rapid determination and reaction/corrective action for trial of security violation and information leakage, phased and systematic security policy by individual technology. The majority of the leaks are caused by former and current staff members, cooperated businesses, scientists and investment companies. This shows that the sources of the leaks are internal personnel. In this manner, we can infer that the management and plan of personnel security has not implemented sound practices to prevent technology leak by people. Therefore, this thesis suggests classifying methods of technology leak through clustering, one of the data mining methods about the information of internal personnel to prevent core technology leak from businesses. 相似文献
552.
DNA methyltransferase 1 (EC 2.1.1.37), encoded by DNMT1 gene, is one of key enzymes in maintaining DNA methylation patterns of the human genome. It plays a crucial role in embryonic development, imprinting and genome stability, cell differentiation. The dysfunction of this group of enzymes can lead to a variety of human genetic disorders. Until now, mutations in DNMT1 have been found to be associated with two distinct phenotypes. Mutations in exon 20 of this gene leads to hereditary sensory and autonomic neuropathy type IE, and mutations in exon 21 cause autosomal dominant cerebellar ataxia, deafness and narcolepsy. Here we report a novel DNMT1 mutation in a sporadic case of a Chinese patient with cerebellar ataxia, multiple motor and sensory neuropathy, hearing loss and psychiatric manifestations. Furthermore, we elucidated its pathogenic effect through molecular genetics studies and revealed that this defective DNMT1 function is responsible for the phenotypes in this individual. Our findings expand the spectrum of DNMT1-related disorders and provide a good example of precision medicine through the combination of exome sequencing and clinical testing. 相似文献
553.
554.
555.
In this work, we first present a method to experimentally capture the free flight of a beetle (Allomyrina dichotoma), which is not an active flyer. The beetle is suspended in the air by a hanger to induce the free flight. This flight is filmed using two high-speed cameras. The high speed images are then examined to obtain flapping angle, flapping frequency, and wing rotation of the hind wing. The acquired data of beetle free flight are used to design a motor-driven flapper that can approximately mimic the beetle in terms of size, flapping frequency and wing kinematics. The flapper can create a large flapping angle over 140° with a large passive wing rotation angle. Even though the flapping frequency of the flapper is not high enough compared to that of a real beetle due to the limited motor torque, the flapper could produce positive average vertical force. This work will provide important experience for future development of a beetle-mimicking Flapping-Wing Micro Air Vehicle (FWMAV). 相似文献
556.
Lucio Cocco Silvia Rubbini Lucia Manzoli Anna Maria Billi Irene Faenza Daniela Peruzzi Alessandro Matteucci Marco Artico R.Stewart Gilmour Sue Goo Rhee 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》1999,1438(2):295-299
Previous reports from our laboratories and others have hinted that the nucleus is a site for an autonomous signalling system acting through the activation of the inositol lipid cycle. Among phospholipases (PLC) it has been shown previously that PLCβ1 is specifically localised in the nucleus as well as at the plasma membrane. Using NIH 3T3 cells, it has been possible to obtain, with two purification strategies, in the presence or in the absence of Nonidet P-40, both intact nuclei still maintaining the outer membrane and nuclei completely stripped of their envelope. In these nuclei, we show that not only PLCβ1 is present, but also PLCβ2, PLCβ3 and PLCβ4. The more abounding isoform is PLCβ1 followed by PLCβ3, PLCβ2 and PLCβ4, respectively. All the isoforms are enriched in nuclear preparations free from nuclear envelope and cytoplasmatic debris, indicating that the actual localisation of the PLCβ isozymes is in the inner nuclear compartment. 相似文献
557.