全文获取类型
收费全文 | 4405篇 |
免费 | 217篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 61篇 |
综合类 | 1篇 |
化学工业 | 835篇 |
金属工艺 | 86篇 |
机械仪表 | 72篇 |
建筑科学 | 81篇 |
矿业工程 | 10篇 |
能源动力 | 109篇 |
轻工业 | 493篇 |
水利工程 | 33篇 |
石油天然气 | 14篇 |
无线电 | 234篇 |
一般工业技术 | 502篇 |
冶金工业 | 1704篇 |
原子能技术 | 22篇 |
自动化技术 | 369篇 |
出版年
2024年 | 7篇 |
2023年 | 36篇 |
2022年 | 87篇 |
2021年 | 144篇 |
2020年 | 105篇 |
2019年 | 107篇 |
2018年 | 129篇 |
2017年 | 132篇 |
2016年 | 141篇 |
2015年 | 88篇 |
2014年 | 100篇 |
2013年 | 236篇 |
2012年 | 175篇 |
2011年 | 199篇 |
2010年 | 159篇 |
2009年 | 161篇 |
2008年 | 150篇 |
2007年 | 118篇 |
2006年 | 94篇 |
2005年 | 61篇 |
2004年 | 63篇 |
2003年 | 75篇 |
2002年 | 53篇 |
2001年 | 45篇 |
2000年 | 41篇 |
1999年 | 75篇 |
1998年 | 447篇 |
1997年 | 309篇 |
1996年 | 218篇 |
1995年 | 139篇 |
1994年 | 103篇 |
1993年 | 112篇 |
1992年 | 25篇 |
1991年 | 44篇 |
1990年 | 39篇 |
1989年 | 44篇 |
1988年 | 33篇 |
1987年 | 28篇 |
1986年 | 21篇 |
1985年 | 24篇 |
1984年 | 12篇 |
1983年 | 20篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 23篇 |
1979年 | 5篇 |
1978年 | 14篇 |
1977年 | 51篇 |
1976年 | 96篇 |
1973年 | 4篇 |
排序方式: 共有4626条查询结果,搜索用时 312 毫秒
1.
2.
Isabel Fernandes Cecília Melo-Alvim Raquel Lopes-Brs Miguel Esperana-Martins Luís Costa 《International journal of molecular sciences》2021,22(2)
Osteosarcoma (OS) is a rare condition with very poor prognosis in a metastatic setting. Basic research has enabled a better understanding of OS pathogenesis and the discovery of new potential therapeutic targets. Phase I and II clinical trials are already ongoing, with some promising results for these patients. This article reviews OS pathogenesis and new potential therapeutic targets. 相似文献
3.
4.
Gomes A. C. S. A. Costa L. C. Brito D. C. Frana R. J. Marques Mnica R. C. 《Polymer Bulletin》2020,77(4):1969-1981
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with... 相似文献
5.
6.
7.
8.
Piedade M. Sousa L. A. de Almeida T. M. Germano J. da Costa B. A. Lemos J. M. Freitas P. P. Ferreira H. A. Cardoso F. A. 《IEEE transactions on circuits and systems. I, Regular papers》2006,53(11):2384-2395
This paper presents a hand-held microsystem based on new fully integrated magnetoresistive biochips for biomolecular recognition (DNA hybridization, antibody antigen interaction, etc.). Magnetoresistive chip surfaces are chemically treated, enabling the immobilization of probe biomolecules such as DNA or antibodies. Fluid handling is also integrated in the biochip. The proposed microsystem not only integrates the biochip, which is an array of 16times16 magnetoresistive sensors, but it also provides all the electronic circuitry for addressing and reading out each transducer. The proposed architecture and circuits were specifically designed for achieving a compact, programmable and portable microsystem. The microsystem also integrates a hand-held analyzer connected through a wireless channel. A prototype of the system was already developed and detection of magnetic nanoparticles was obtained. This indicates that the system may be used for magnetic label based bioassays 相似文献
9.
The Woodman Point Wastewater Treatment Plant (WWTP) in Western Australia has experienced two separate problems causing avoidable maintenance costs: the build-up of massive struvite (MgNH4PO4. 6H2O) scaling downstream of the anaerobic digester and the formation of hydrogen sulfide (H2S) levels in the digester gas to levels that compromised gas engine operation and caused high operating costs on the gas scrubber. As both problems hang together with a chemical imbalance in the anaerobic digester, we decided to investigate whether both problems could be (feasibly and economically) addressed by a common solution (such as dosing of iron solutions to precipitate both sulfide and phosphate), or by using separate approaches. Laboratory results showed that, the hydrogen sulfide emission in digesters could be effectively and economically controlled by the addition of iron dosing. Slightly higher than the theoretical value of 1.5 mol of FeCl3 was required to precipitate 1 mol of dissolved sulfide inside the digester. Due to the high concentration of PO4(3-) in the digested sludge liquor, significantly higher iron is required for struvite precipitation. Iron dosing did not appear an economic solution for struvite control via iron phosphate formation. By taking advantage of the natural tendency of struvite formation in the digester liquid, it is possible to reduce the risk of struvite precipitation in and around the sludge-dewatering centrifuge by increasing the pH to precipitate struvite out before passing through the centrifuge. However, as the Mg2+/PO4(3-) molar ratio in digested sludge was low, by increasing the pH alone (using NaOH) the precipitation of PO4(3-) was limited by the amount of cations (Ca2+ and Mg2+) available in the sludge. Although this would reduce struvite precipitation in the centrifuge, it could not significantly reduce PO4(3-) recycling back to the plant. For long-term operation, maximum PO4(3-) reduction should be the ultimate aim to minimise PO4(3-) accumulation in the plant. Magnesium hydroxide liquid (MHL) was found to be the most cost-effective chemical to achieve this goal. It enhanced struvite precipitation from both, digested sludge and centrate to the point where more than 95% PO4(3-) reduction in the digested sludge was achieved. 相似文献
10.
J Stagsted S Ziebe S Satoh GD Holman SW Cushman L Olsson 《Canadian Metallurgical Quarterly》1993,268(3):1770-1774
Peptides derived from the alpha 1-region of the murine H-2Dk molecule enhance glucose uptake in rat adipose cells above the maximum obtained with insulin stimulation alone (Stagsted, J., Reaven, G. M., Hansen, T., Goldstein, A., and Olsson, L. (1990) Cell 62, 297-307). We now describe that epidermal growth factor (EGF) in combination with the same peptides, Dk-(61-85) and Dk-(62-85), stimulates cellular glucose uptake 5-7 times over the basal level, i.e. to 30-50% of the maximal insulin effect. EGF alone increased glucose uptake by only approximately 50% above basal and the peptide alone by 100% above basal. Maximal effect of EGF and peptide was reached in 10-20 min with 30 microM peptide (EC50 10-15 microM) and 50 nM EGF (EC50 1-2 nM). The effect of EGF and peptide on glucose uptake was additive to that of insulin and peptide until the maximal level attained with insulin and peptide was reached. The combined effect of EGF plus peptide on glucose transport was associated with a recruitment of GLUT4 molecules to the plasma membrane. However, the phosphatidylinositol (PI) kinase which is activated by insulin was not activated by EGF plus peptide. Thus, the effect of EGF plus peptide on glucose uptake seems independent of the activity status of the insulin receptor. 125I-Labeled EGF bound specifically to rat adipose cells with an apparent affinity of approximately 2 nM and Bmax approximately 5 x 10(3). However, the major histocompatibility complex (MHC) peptides did not affect EGF-stimulated internalization of EGF receptor, in contrast to their effect on the insulin receptors. Transforming growth factor alpha had an effect similar to EGF on glucose uptake. Three other peptides derived from other parts of murine MHC class I had no effect on glucose uptake in combination with EGF. Thus, EGF in combination with certain MHC class I-derived peptides is insulinomimetic concerning glucose transport and this effect is independent of the insulin receptor activity. 相似文献