全文获取类型
收费全文 | 24995篇 |
免费 | 1383篇 |
国内免费 | 36篇 |
专业分类
电工技术 | 164篇 |
综合类 | 27篇 |
化学工业 | 5570篇 |
金属工艺 | 501篇 |
机械仪表 | 459篇 |
建筑科学 | 898篇 |
矿业工程 | 46篇 |
能源动力 | 918篇 |
轻工业 | 4645篇 |
水利工程 | 231篇 |
石油天然气 | 136篇 |
武器工业 | 2篇 |
无线电 | 1205篇 |
一般工业技术 | 3712篇 |
冶金工业 | 4059篇 |
原子能技术 | 188篇 |
自动化技术 | 3653篇 |
出版年
2023年 | 191篇 |
2022年 | 192篇 |
2021年 | 739篇 |
2020年 | 511篇 |
2019年 | 621篇 |
2018年 | 738篇 |
2017年 | 770篇 |
2016年 | 834篇 |
2015年 | 720篇 |
2014年 | 968篇 |
2013年 | 1712篇 |
2012年 | 1429篇 |
2011年 | 1836篇 |
2010年 | 1352篇 |
2009年 | 1361篇 |
2008年 | 1238篇 |
2007年 | 1040篇 |
2006年 | 915篇 |
2005年 | 774篇 |
2004年 | 701篇 |
2003年 | 624篇 |
2002年 | 552篇 |
2001年 | 354篇 |
2000年 | 319篇 |
1999年 | 351篇 |
1998年 | 1373篇 |
1997年 | 887篇 |
1996年 | 636篇 |
1995年 | 374篇 |
1994年 | 330篇 |
1993年 | 323篇 |
1992年 | 126篇 |
1991年 | 118篇 |
1990年 | 88篇 |
1989年 | 113篇 |
1988年 | 89篇 |
1987年 | 85篇 |
1986年 | 66篇 |
1985年 | 106篇 |
1984年 | 70篇 |
1983年 | 53篇 |
1982年 | 55篇 |
1981年 | 59篇 |
1980年 | 63篇 |
1979年 | 36篇 |
1978年 | 30篇 |
1977年 | 95篇 |
1976年 | 188篇 |
1975年 | 33篇 |
1973年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Patricia Garrido-Pascual Ana Alonso-Varona Begoa Castro María Burn Teodoro Palomares 《International journal of molecular sciences》2020,21(24)
Oxidative stress associated with neuroinflammation is a key process involved in the pathophysiology of neurodegenerative diseases, and therefore, has been proposed as a crucial target for new therapies. Recently, the therapeutic potential of human adipose-derived stem cells (hASCs) has been investigated as a novel strategy for neuroprotection. These cells can be preconditioned by exposing them to mild stress in order to improve their response to oxidative stress. In this study, we evaluate the therapeutic potential of hASCs preconditioned with low doses of H2O2 (called HC016 cells) to overcome the deleterious effect of oxidative stress in an in vitro model of oligodendrocyte-like cells (HOGd), through two strategies: i, the culture of oxidized HOGd with HC016 cell-conditioned medium (CM), and ii, the indirect co-culture of oxidized HOGd with HC016 cells, which had or had not been exposed to oxidative stress. The results demonstrated that both strategies had reparative effects, oxidized HC016 cell co-culture being the one associated with the greatest recovery of the damaged HOGd, increasing their viability, reducing their intracellular reactive oxygen species levels and promoting their antioxidant capacity. Taken together, these findings support the view that HC016 cells, given their reparative capacity, might be considered an important breakthrough in cell-based therapies. 相似文献
72.
Georgia-Ioanna Kartalou Ana Rita Salgueiro-Pereira Thomas Endres Angelina Lesnikova Plinio Casarotto Paula Pousinha Kevin Delanoe Elke Edelmann Eero Castrn Kurt Gottmann Hlne Marie Volkmar Lessmann 《International journal of molecular sciences》2020,21(23)
Therapeutic approaches providing effective medication for Alzheimer’s disease (AD) patients after disease onset are urgently needed. Previous studies in AD mouse models suggested that physical exercise or changed lifestyle can delay AD-related synaptic and memory dysfunctions when treatment started in juvenile animals long before onset of disease symptoms, while a pharmacological treatment that can reverse synaptic and memory deficits in AD mice was thus far not identified. Repurposing food and drug administration (FDA)-approved drugs for treatment of AD is a promising way to reduce the time to bring such medication into clinical practice. The sphingosine-1 phosphate analog fingolimod (FTY720) was approved recently for treatment of multiple sclerosis patients. Here, we addressed whether fingolimod rescues AD-related synaptic deficits and memory dysfunction in an amyloid precursor protein/presenilin-1 (APP/PS1) AD mouse model when medication starts after onset of symptoms (at five months). Male mice received intraperitoneal injections of fingolimod for one to two months starting at five to six months. This treatment rescued spine density as well as long-term potentiation in hippocampal cornu ammonis-1 (CA1) pyramidal neurons, that were both impaired in untreated APP/PS1 animals at six to seven months of age. Immunohistochemical analysis with markers of microgliosis (ionized calcium-binding adapter molecule 1; Iba1) and astrogliosis (glial fibrillary acid protein; GFAP) revealed that our fingolimod treatment regime strongly down regulated neuroinflammation in the hippocampus and neocortex of this AD model. These effects were accompanied by a moderate reduction of Aβ accumulation in hippocampus and neocortex. Our results suggest that fingolimod, when applied after onset of disease symptoms in an APP/PS1 mouse model, rescues synaptic pathology that is believed to underlie memory deficits in AD mice, and that this beneficial effect is mediated via anti-neuroinflammatory actions of the drug on microglia and astrocytes. 相似文献
73.
74.
Dr. Ilhem Khelifi Shannon Pecnard Dr. Guillaume Bernadat Dr. Jérome Bignon Dr. Hélène Levaique Dr. Joëlle Dubois Dr. Olivier Provot Dr. Mouad Alami 《ChemMedChem》2020,15(16):1571-1578
In this article, we report the synthesis and biological properties of a series of novel oxazepines related to isoCA-4 having significant antitumor properties. Among them, three oxazepin-9-ol derivatives display a nanomolar or a sub-nanomolar cytotoxicity level against five human cancer cell lines (HCT116, U87, A549, MCF7, and K562). It was demonstrated that the lead compound in this series inhibits tubulin assembly with an IC50 value of 1 μM and totally arrests the cellular cycle in the G2/M phase at the low concentration of 5 nM in HCT116 and K562 cells. Molecular modeling studies perfectly corroborates these promising results. 相似文献
75.
76.
77.
Javier Andrés Bocchio Mariano Martín Escobar Javier Carlos Quagliano Amado 《Polymer Engineering and Science》2020,60(3):630-635
Ablation resistance and mechanical properties of polyurethane-based composites containing different amounts (up to 5 wt%) of organoclay were correlated with the morphological characterization. The crosslinking density of the polyurethane increased with the amount of organoclay. At low concentration (up to 1 wt%), the organoclay was well exfoliated, while at higher concentration, both exfoliated and intercalated platelets were found. A linear correlation was observed between the tensile test and the concentration of organoclay. Erosion velocity decreased 40% with the incorporation of 5% of organoclay. POLYM. ENG. SCI., 60:630–635, 2020. © 2020 Society of Plastics Engineers 相似文献
78.
Imane Mayouf Melia Guessoum Mónica Fuensanta José Miguel Martín Martìnez 《Polymer Engineering and Science》2020,60(5):944-955
The potential of ε-caprolactam (CAP) and trimellitic anhydride (TMA) compounds as novel chain extenders for poly(lactic acid) (PLA) has been assessed; the amounts of 0.01, 0.025, and 0.05 wt% each additive have been added. The chain extension was evidenced by the increase in PLA/CAP and PLA/TMA viscosities in mixing torque measurements and by infrared spectroscopy. PLA reaction with CAP and TMA has also been confirmed from contact angle and surface free energy studies, which have shown that the increase in TMA amount decreased the hydrophilicity of PLA due to the decreased concentration of terminal surface hydroxyl groups. However, the addition of CAP accentuated the PLA hydrophilicity as indicated by the increase in the polar component of the surface energy. On the other hand, the glass transition temperature of PLA/TMA and PLA/CAP decreased as a result of a local plasticizing effect, which favored the chain mobility and the crystallization of PLA due to the concomitant nucleating effect of the chain extenders moieties too. Furthermore, the higher molecular weight of PLA/CAP and PLA/TMA was responsible for their increased thermal stability and higher impact strength with respect to PLA. POLYM. ENG. SCI., 60:944–955, 2020. © 2020 Society of Plastics Engineers 相似文献
79.
80.
Russian Journal of Nondestructive Testing - The present study investigates the influence of degradation effects due to natural aging of wood beams from the Cathedral of Morelia, Mexico by using... 相似文献