全文获取类型
收费全文 | 1283篇 |
免费 | 112篇 |
国内免费 | 84篇 |
专业分类
电工技术 | 15篇 |
综合类 | 47篇 |
化学工业 | 774篇 |
金属工艺 | 86篇 |
机械仪表 | 32篇 |
建筑科学 | 17篇 |
矿业工程 | 27篇 |
能源动力 | 16篇 |
轻工业 | 152篇 |
水利工程 | 2篇 |
石油天然气 | 43篇 |
武器工业 | 13篇 |
无线电 | 22篇 |
一般工业技术 | 83篇 |
冶金工业 | 72篇 |
原子能技术 | 69篇 |
自动化技术 | 9篇 |
出版年
2024年 | 1篇 |
2023年 | 19篇 |
2022年 | 70篇 |
2021年 | 94篇 |
2020年 | 37篇 |
2019年 | 48篇 |
2018年 | 36篇 |
2017年 | 40篇 |
2016年 | 42篇 |
2015年 | 42篇 |
2014年 | 86篇 |
2013年 | 127篇 |
2012年 | 78篇 |
2011年 | 75篇 |
2010年 | 47篇 |
2009年 | 51篇 |
2008年 | 48篇 |
2007年 | 71篇 |
2006年 | 63篇 |
2005年 | 58篇 |
2004年 | 55篇 |
2003年 | 49篇 |
2002年 | 44篇 |
2001年 | 38篇 |
2000年 | 22篇 |
1999年 | 21篇 |
1998年 | 18篇 |
1997年 | 22篇 |
1996年 | 16篇 |
1995年 | 18篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 1篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有1479条查询结果,搜索用时 15 毫秒
31.
AbstractNitric oxide (NO) plays a critical role in the regulation of a wide variety of physiological processes. It is a potent inhibitor of platelet adhesion and aggregation, inhibits bacterial adhesion and proliferation, is implicated in mediating the inflammatory response toward implanted devices, plays a role in tumor growth and proliferation, and is a neurotransmitter. Herein, we describe the synthesis and NO-release properties of a modified polydimethylsiloxane that contains S-nitroso-N-acetyl-D-penicillamine covalently attached to the cross-linking agent (SNAP–DMS). Light from a C503B-BAN-CY0C0461 light-emitting diode (470 nm) was used as an external trigger to allow precise control over level and duration of NO release ranging from a surface flux of zero to approximately 3.5×10?10 mol cm-2 min-1. SNAP–PDMS films stored in the dark released NO after 297 days, indicating the long-term stability of SNAP–PDMS. 相似文献
32.
Mikhail G. Akimov Alina M. Gamisonia Polina V. Dudina Natalia M. Gretskaya Anastasia A. Gaydaryova Andrey S. Kuznetsov Galina N. Zinchenko Vladimir V. Bezuglov 《International journal of molecular sciences》2021,22(2)
GPR55 is a GPCR of the non-CB1/CB2 cannabinoid receptor family, which is activated by lysophosphatidylinositol (LPI) and stimulates the proliferation of cancer cells. Anandamide, a bioactive lipid endocannabinoid, acts as a biased agonist of GPR55 and induces cancer cell death, but is unstable and psychoactive. We hypothesized that other endocannabinoids and structurally similar compounds, which are more hydrolytically stable, could also induce cancer cell death via GPR55 activation. We chemically synthesized and tested a set of fatty acid amides and esters for cell death induction via GPR55 activation. The most active compounds appeared to be N-acyl dopamines, especially N-docosahexaenoyl dopamine (DHA-DA). Using a panel of cancer cell lines and a set of receptor and intracellular signal transduction machinery inhibitors together with cell viability, Ca2+, NO, ROS (reactive oxygen species) and gene expression measurement, we showed for the first time that for these compounds, the mechanism of cell death induction differed from that published for anandamide and included neuronal nitric oxide synthase (nNOS) overstimulation with concomitant oxidative stress induction. The combination of DHA-DA with LPI, which normally stimulates cancer proliferation and is increased in cancer setting, had an increased cytotoxicity for the cancer cells indicating a therapeutic potential. 相似文献
33.
34.
Ssu-Han Chen Shih-Jiuan Chiu Teh-Min Hu 《International journal of molecular sciences》2012,13(11):13985-14001
Nitric oxide (NO) is an important molecule that exerts multiple functions in biological systems. Because of the short-lived nature of NO, S-nitrosothiols (RSNOs) are believed to act as stable NO carriers. Recently, sulfhydryl (SH) containing macromolecules have been shown to be promising NO carriers. In the present study, we aimed to synthesize and characterize a potential NO carrier based on bovine Cu,Zn-superoxide dismutase (bSOD). To prepare S-nitrosated bSOD, the protein was incubated with S-nitrosoglutathione (GSNO) under varied experimental conditions. The results show that significant S-nitrosation of bSOD occurred only at high temperature (50 °C) for prolonged incubation time (>2 h). S-nitrosation efficiency increased with reaction time and reached a plateau at ~4 h. The maximum amount of NO loaded was determined to be about 0.6 mol SNO/mol protein (~30% loading efficiency). The enzymatic activity of bSOD, however, decreased with reaction time. Our data further indicate that NO functionality can only be measured in the presence of extremely high concentrations of Hg2+ or when the protein was denatured by guanidine. Moreover, mildly acidic pH was shown to favor S-nitrosation of bSOD. A model based on unfolding and refolding of bSOD during preparation was proposed to possibly explain our observation. 相似文献
35.
Xiao Liu Yubo Fan X. Yun Xu Xiaoyan Deng 《Journal of the Royal Society Interface》2012,9(75):2468-2478
To test the hypothesis that disturbed flow can impede the transport of nitric oxide (NO) in the artery and hence induce atherogenesis, we used a lumen–wall model of an idealized arterial stenosis with NO produced at the blood vessel–wall interface to study the transport of NO in the stenosis. Blood flows in the lumen and through the arterial wall were simulated by Navier–Stokes equations and Darcy''s Law, respectively. Meanwhile, the transport of NO in the lumen and the transport of NO within the arterial wall were modelled by advection–diffusion reaction equations. Coupling of fluid dynamics at the endothelium was achieved by the Kedem–Katchalsky equations. The results showed that both the hydraulic conductivity of the endothelium and the non-Newtonian viscous behaviour of blood had little effect on the distribution of NO. However, the blood flow rate, stenosis severity, red blood cells (RBCs), RBC-free layer and NO production rate at the blood vessel–wall interface could significantly affect the transport of NO. The theoretical study revealed that the transport of NO was significantly hindered in the disturbed flow region distal to the stenosis. The reduced NO concentration in the disturbed flow region might play an important role in the localized genesis and development of atherosclerosis. 相似文献
36.
Rui Yang Huaying Du Ying Sun Fengying Zhang Wei Zhang Chunpeng Wan Jinyin Chen Liqin Zhu 《International Journal of Food Science & Technology》2021,56(10):5259-5267
The present study evaluated the effects of 15 μL L-1 nitric oxide (NO) on the fruit defence response of ‘Newhall’ navel orange. The decay rate of NO-treated navel orange fruits was significantly lower than that of control fruits during storage at 20 °C storage (P < 0.05). Treatment with NO suppressed the increase in disease incidence and lesion area in orange fruits inoculated with Penicillium italicum (P. italicum); significantly increased the activities of phenolic metabolism-associated enzymes and pathogenesis-related (PR) proteins, including polyphenoloxidase (PPO), phenylalanine ammonia-lyase (PAL), β-1,3-glucanase (GLU) and chitinase (CHT); and enhanced the activities of key enzymes, including 4-coumarate: CoA ligase (4CL), cinnamate-4-hydroxylase (C4H) and chalcone isomerase (CHI) in the phenylpropanoid pathway. The contents of total phenolics, flavonoids and lignin were also higher in NO-treated fruits than in control fruits. The findings suggest that exogenous NO could induce disease resistance against P. italicum in navel orange fruits. 相似文献
37.
Yüksel Korkmaz Behrus Puladi Kerstin Galler Peer W. Kmmerer Agnes Schrder Lina Glz Tim Sparwasser Wilhelm Bloch Andreas Friebe James Deschner 《International journal of molecular sciences》2021,22(2)
Nitric oxide (NO) binds to soluble guanylyl cyclase (sGC), activates it in a reduced oxidized heme iron state, and generates cyclic Guanosine Monophosphate (cGMP), which results in vasodilatation and inhibition of osteoclast activity. In inflammation, sGC is oxidized and becomes insensitive to NO. NO- and heme-independent activation of sGC requires protein expression of the α1- and β1-subunits. Inflammation of the periodontium induces the resorption of cementum by cementoclasts and the resorption of the alveolar bone by osteoclasts, which can lead to tooth loss. As the presence of sGC in cementoclasts is unknown, we investigated the α1- and β1-subunits of sGC in cementoclasts of healthy and inflamed human periodontium using double immunostaining for CD68 and cathepsin K and compared the findings with those of osteoclasts from the same sections. In comparison to cementoclasts in the healthy periodontium, cementoclasts under inflammatory conditions showed a decreased staining intensity for both α1- and β1-subunits of sGC, indicating reduced protein expression of these subunits. Therefore, pharmacological activation of sGC in inflamed periodontal tissues in an NO- and heme-independent manner could be considered as a new treatment strategy to inhibit cementum resorption. 相似文献
38.
分析了硝酸镁法生产浓硝酸过程中稀硝酸镁含硝量高的危害性。通过采取加强对加热器的维护、优化硝酸镁沉降方法和改变硝酸镁投料方式等一系列优化改进措施,提升了浓硝酸装置连续运行能力,降低了装置综合能耗。 相似文献
39.
40.