全文获取类型
收费全文 | 1729篇 |
免费 | 4篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 36篇 |
机械仪表 | 3篇 |
建筑科学 | 5篇 |
能源动力 | 9篇 |
轻工业 | 17篇 |
无线电 | 8篇 |
一般工业技术 | 23篇 |
冶金工业 | 1603篇 |
自动化技术 | 28篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 3篇 |
2011年 | 9篇 |
2010年 | 8篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 10篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 39篇 |
1998年 | 490篇 |
1997年 | 290篇 |
1996年 | 186篇 |
1995年 | 107篇 |
1994年 | 77篇 |
1993年 | 119篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 13篇 |
1989年 | 21篇 |
1988年 | 24篇 |
1987年 | 21篇 |
1986年 | 28篇 |
1985年 | 21篇 |
1983年 | 2篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 42篇 |
1976年 | 85篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1733条查询结果,搜索用时 15 毫秒
31.
Understanding the mechanisms responsible for photodamage to the skin is most important for dermatology. 3-D cultures have been used as tools to mimic the in vivo situation for several years. We irradiated such a system containing human dermal fibroblasts cultured in collagen gels, a well-known model considered to be a dermal equivalent, which reproduces the interaction between cells and the surrounding extracellular matrix. The effects of solar irradiation (315-800 nm) on the steady-state levels of the mRNAs of extracellular matrix components (type I and III collagens) and their degrading enzymes (interstitial collagenase, MMP-1 and stromelysin 1, MMP-3) were measured. Exposure to low levels of solar radiation (0-10 J cm-2 in the UVA, i.e. suberythemal UVA doses) caused a transient decrease in type I procollagen mRNA, an increase in MMP-mRNA, and no change in type III procollagen mRNA steady-state levels. These results describe the early changes in the connective tissue of the skin following exposure to low-level solar stimulation, and may help explain the long-term changes in photodamaged skin. 相似文献
32.
33.
34.
A G protein gamma subunit-like domain shared between RGS11 and other RGS proteins specifies binding to Gbeta5 subunits 总被引:1,自引:0,他引:1
BE Snow AM Krumins GM Brothers SF Lee MA Wall S Chung J Mangion S Arya AG Gilman DP Siderovski 《Canadian Metallurgical Quarterly》1998,95(22):13307-13312
Regulators of G protein signaling (RGS) proteins act as GTPase-activating proteins (GAPs) toward the alpha subunits of heterotrimeric, signal-transducing G proteins. RGS11 contains a G protein gamma subunit-like (GGL) domain between its Dishevelled/Egl-10/Pleckstrin and RGS domains. GGL domains are also found in RGS6, RGS7, RGS9, and the Caenorhabditis elegans protein EGL-10. Coexpression of RGS11 with different Gbeta subunits reveals specific interaction between RGS11 and Gbeta5. The expression of mRNA for RGS11 and Gbeta5 in human tissues overlaps. The Gbeta5/RGS11 heterodimer acts as a GAP on Galphao, apparently selectively. RGS proteins that contain GGL domains appear to act as GAPs for Galpha proteins and form complexes with specific Gbeta subunits, adding to the combinatorial complexity of G protein-mediated signaling pathways. 相似文献
35.
AE Barker-Griffith BW Streeten JL Abraham DP Schaefer SW Norton 《Canadian Metallurgical Quarterly》1998,105(3):535-538
PURPOSE: This study aimed to identify a dangerous new weapon capable of causing damage to the ocular and periocular regions. METHODS: The authors report two patients who had penetrating ocular injury in the past year because of homemade recreational potato guns. RESULTS: In one 14-year-old boy, projectiles from the firing of a potato gun resulted in orbital and cranial injuries that were life threatening with widespread fractures, marked disruption of facial structures, a cerebrospinal fluid fistula requiring bifrontal surgical repair, and loss of one eye. In a separate accident with a different potato gun, a 14-year-old boy who was wearing glasses at the time of injury had a sight-threatening perforating corneal laceration. CONCLUSION: Practitioners must be aware of the existence of these new, homemade unregulated devices. Information about the use and construction of these guns is widespread on the Internet, but no injuries resulting from these guns currently are documented in the medical literature. 相似文献
36.
Stellari F. Peilin Song Tsang J.C. McManus M.K. Ketchen M.B. 《Electron Devices, IEEE Transactions on》2004,51(9):1455-1462
In recent years, innovative applications based on the detection of emission sources such as the light emission from off-state leakage current (LEOSLC) of CMOS transistors have been developed for testing and diagnosing modern ultralarge-scale integration circuits. In this paper, we show that LEOSLC can be used to effectively debug circuits, localize defects with a quick turn around time, read the logic state of gates, and extract the internal voltage drop of power distribution grids among others. 相似文献
37.
38.
39.
40.
Poor service provision within the global software services industryis contributing to a profound rethink in many firms that offerinformation and technology services. Recent press reports suggestthat all but a few software providers are willing to committhe organisation and its resources to high volume high riskservice provision. 相似文献