全文获取类型
收费全文 | 12371篇 |
免费 | 760篇 |
国内免费 | 41篇 |
学科分类
工业技术 | 13172篇 |
出版年
2024年 | 3篇 |
2023年 | 155篇 |
2022年 | 77篇 |
2021年 | 395篇 |
2020年 | 282篇 |
2019年 | 326篇 |
2018年 | 367篇 |
2017年 | 420篇 |
2016年 | 457篇 |
2015年 | 378篇 |
2014年 | 554篇 |
2013年 | 825篇 |
2012年 | 833篇 |
2011年 | 1016篇 |
2010年 | 734篇 |
2009年 | 781篇 |
2008年 | 722篇 |
2007年 | 569篇 |
2006年 | 494篇 |
2005年 | 447篇 |
2004年 | 414篇 |
2003年 | 368篇 |
2002年 | 374篇 |
2001年 | 274篇 |
2000年 | 227篇 |
1999年 | 212篇 |
1998年 | 337篇 |
1997年 | 226篇 |
1996年 | 168篇 |
1995年 | 123篇 |
1994年 | 110篇 |
1993年 | 93篇 |
1992年 | 64篇 |
1991年 | 57篇 |
1990年 | 50篇 |
1989年 | 56篇 |
1988年 | 30篇 |
1987年 | 39篇 |
1986年 | 18篇 |
1985年 | 30篇 |
1984年 | 16篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
31.
Chi-Ho Lee Arjun Sapkota Bhakta Prasad Gaire Ji Woong Choi 《International journal of molecular sciences》2020,21(22)
Lysophosphatidic acid receptor 1 (LPA1) contributes to brain injury following transient focal cerebral ischemia. However, the mechanism remains unclear. Here, we investigated whether nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation might be an underlying mechanism involved in the pathogenesis of brain injury associated with LPA1 following ischemic challenge with transient middle cerebral artery occlusion (tMCAO). Suppressing LPA1 activity by its antagonist attenuated NLRP3 upregulation in the penumbra and ischemic core regions, particularly in ionized calcium-binding adapter molecule 1 (Iba1)-expressing cells like macrophages of mouse after tMCAO challenge. It also suppressed NLRP3 inflammasome activation, such as caspase-1 activation, interleukin 1β (IL-1β) maturation, and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) speck formation, in a post-ischemic brain. The role of LPA1 in NLRP3 inflammasome activation was confirmed in vitro using lipopolysaccharide-primed bone marrow-derived macrophages, followed by LPA exposure. Suppressing LPA1 activity by either pharmacological antagonism or genetic knockdown attenuated NLRP3 upregulation, caspase-1 activation, IL-1β maturation, and IL-1β secretion in these cells. Furthermore, nuclear factor-κB (NF-κB), extracellular signal-regulated kinase 1/2 (ERK1/2), and p38 were found to be LPA1-dependent effector pathways in these cells. Collectively, results of the current study first demonstrate that LPA1 could contribute to ischemic brain injury by activating NLRP3 inflammasome with underlying effector mechanisms. 相似文献
32.
33.
Seung-Hwan Lee Jin-Myung Choi Jae-Hong Lim Jozeph Park Jin-Seong Park 《Ceramics International》2018,44(2):1978-1983
The thermoelectric properties of aluminum-doped tin oxide (ATO) thin films synthesized by thermal atomic layer deposition (ALD) were studied with respect to the aluminum concentration. The overall aluminum content in each layer was modulated by adjusting the relative number of tin oxide (SnO2) and aluminum oxide (Al2O3) growth cycles, where a sequential process involving n cycles of SnO2 growth followed by 1 cycle of Al2O3 deposition was performed (building up a super-cycle). The electrical conductivity (620 S/cm), free carrier concentration (1.23x1021 cm-3), and power factor (0.49 mW/K2m) increase until their maximum values are reached when the Al content is approximately 1.50 at% of the cations, and decrease as more Al is added in. On the other hand, the Seebeck coefficient decreases monotonically as the Al content increases up to about 2.88 at%, and begins to increase with further Al doping. Here the thermoelectric efficiency is therefore determined primarily by the free carrier concentration, while the Seebeck coefficient appears to be influenced by the overall crystal structure. 相似文献
34.
Ju-Hwan Han Jin-Myung Choi Seong-Hyeon Lee Woojin Jeon Jin-Seong Park 《Ceramics International》2018,44(17):20890-20895
Silicon nitride (Si3N4) films have received great attention not only as dielectric materials for the gate dielectric of transistors and the insulator of capacitors, but also as a buffer layer and etch-stop layer for the semiconductor industry. As the applications of Si3N4 film increase, the necessity of investigating a novel deposition process applicable at low temperature has emerged. In this regard, the plasma-enhanced atomic layer deposition (PEALD) technique is attractive as a promising process; however, the Si3N4 film deposition process at growth temperatures less than 150?°C using PEALD has not been investigated. In this work, the growth behavior and chemistry of SiNx (x?<?1.33) film deposited by the PEALD process at various growth temperatures were developed. Insufficient thermal energy from low growth temperature induces an unstable chemical state of deposited film due to the remaining unreacted ligand of adsorbed precursors. This state results in a further chemical reaction to SiO2 formation by air exposure. Other chemical effects depending on chemical composition and electrical property were also examined in detail. 相似文献
35.
36.
37.
38.
39.
Identifying and Verifying Vulnerabilities through PLC Network Protocol and Memory Structure Analysis
Joo-Chan Lee Hyun-Pyo Choi Jang-Hoon Kim Jun-Won Kim Da-Un Jung Ji-Ho Shin Jung-Taek Seo 《计算机、材料和连续体(英文)》2020,65(1):53-67
Cyberattacks on the Industrial Control System (ICS) have recently been
increasing, made more intelligent by advancing technologies. As such, cybersecurity for
such systems is attracting attention. As a core element of control devices, the
Programmable Logic Controller (PLC) in an ICS carries out on-site control over the ICS. A
cyberattack on the PLC will cause damages on the overall ICS, with Stuxnet and Duqu as
the most representative cases. Thus, cybersecurity for PLCs is considered essential, and
many researchers carry out a variety of analyses on the vulnerabilities of PLCs as part of
preemptive efforts against attacks. In this study, a vulnerability analysis was conducted on
the XGB PLC. Security vulnerabilities were identified by analyzing the network protocols
and memory structure of PLCs and were utilized to launch replay attack, memory
modulation attack, and FTP/Web service account theft for the verification of the results.
Based on the results, the attacks were proven to be able to cause the PLC to malfunction
and disable it, and the identified vulnerabilities were defined. 相似文献
40.
Wontae Lee Soyeong Yun Hao Li Jaeyoung Kim Hayeon Lee Kyeongkeun Kwon Jin Yong Lee Young‐Min Choi Won‐Sub Yoon 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(5)
The anionic redox chemistries of layered cathode materials have been in focus recently due to an intriguing phenomenon that cannot be described by the number of electrons of transition metal ions. However, even though several studies have investigated the anionic redox chemistry of layered materials in terms of the charge compensation, the relationship between the origin of the structural behavior and anionic redox chemistry in layered materials remains poorly understood. In addition, a simultaneous redox process of transition metal ions could occur through the d bands interaction. Here, it is demonstrated that the anionic redox chemistry is associated with the anisotropic structural behavior of the layered cathode materials albeit without providing additional capacities exceeding the theoretical values. These findings will provide a foundation of a new chapter in the understanding of the properties of materials. 相似文献