全文获取类型
收费全文 | 1990篇 |
免费 | 76篇 |
国内免费 | 11篇 |
专业分类
化学 | 1417篇 |
晶体学 | 23篇 |
力学 | 65篇 |
数学 | 163篇 |
物理学 | 409篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 57篇 |
2021年 | 65篇 |
2020年 | 59篇 |
2019年 | 51篇 |
2018年 | 38篇 |
2017年 | 41篇 |
2016年 | 62篇 |
2015年 | 55篇 |
2014年 | 75篇 |
2013年 | 139篇 |
2012年 | 152篇 |
2011年 | 153篇 |
2010年 | 91篇 |
2009年 | 86篇 |
2008年 | 155篇 |
2007年 | 119篇 |
2006年 | 121篇 |
2005年 | 91篇 |
2004年 | 101篇 |
2003年 | 53篇 |
2002年 | 76篇 |
2001年 | 32篇 |
2000年 | 42篇 |
1999年 | 18篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 20篇 |
1995年 | 10篇 |
1994年 | 17篇 |
1993年 | 15篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1969年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有2077条查询结果,搜索用时 15 毫秒
61.
Many different types of urine proteome studies have been done, but urine glycoprotein studies are insufficient. Therefore, we studied the glycoproteins from rat urine, which could be used to identify biomarkers in an animal model. First, urinary proteins were prepared by using the dialysis and lyophilizing methods from rat urine. Glycoproteins enriched with lectin affinity purification, concanavalin A, jacalin and wheat germ agglutinin from the urinary proteins were separated by means of reverse-phase fast protein LC (FPLC) or 1-D PAGE. Each FPLC fraction and 1-D PAGE gel band were trypsin-digested and analyzed by means of nanoLC-MS/MS. LC-MS/MS analyses were carried out by using linear ion trap MS. A total of 318 rat urinary glycoproteins were identified from the FPLC fractions and gel bands; approximately 90% of identified proteins were confirmed as glycoproteins in Swiss-Prot. Many glycoproteins, known as biomarkers, including C-reactive protein, uromodulin, amyloid beta A4 protein, alpha-1-inhibitor 3, vitamin D-binding protein, kallikrein 3 and fetuin-A were identified in this study. By studying urinary glycoproteins collected from rat, these results may help to assist in identifying urinary biomarkers regarding various types of disease models. 相似文献
62.
Park JH Chung DS Park JW Ahn T Kong H Jung YK Lee J Yi MH Park CE Kwon SK Shim HK 《Organic letters》2007,9(13):2573-2576
New soluble anthracene derivatives containing thiophene and phenylenevinylene derivatives were synthesized via well-known synthetic routes. TIPS derivatives were added at the 9,10-positions of anthracene for the solubility and crystallinity. Both of the molecules were found to be promising for high charge mobility and stable organic semiconductors. The soluble anthracene core (TIPSAnt) is a potential precursor for the synthesis of novel semiconducting materials. 相似文献
63.
64.
Kim EK Kwon KB Han MJ Song MY Lee JH Lv N Ka SO Yeom SR Kwon YD Ryu DG Kim KS Park JW Park R Park BH 《Experimental & molecular medicine》2007,39(2):149-159
We demonstrated previously that Coptidis rhizoma extract (CRE) prevented S-nitroso-N-acetylpenicillamine-induced apoptotic cell death via the inhibition of mitochondrial membrane potential disruption and cytochrome c release in RINm5F (RIN) rat insulinoma cells. In this study, the preventive effects of CRE against cytokine-induced beta-cell death was assessed. Cytokines generated by immune cells infiltrating pancreatic islets are crucial mediators of beta-cell destruction in insulin-dependent diabetes mellitus. The treatment of RIN cells with IL-1beta and IFN-gamma resulted in a reduction of cell viability. CRE completely protected IL-1beta and IFN-gamma-mediated cell death in a concentration-dependent manner. Incubation with CRE induced a significant suppression of IL-1beta and IFN-gamma-induced nitric oxide (NO) production, a finding which correlated well with reduced levels of the iNOS mRNA and protein. The molecular mechanism by which CRE inhibited iNOS gene expression appeared to involve the inhibition of NF-kappaB activation. The IL-1beta and IFN-gamma-stimulated RIN cells showed increases in NF-kappaB binding activity and p65 subunit levels in nucleus, and IkappaB alpha degradation in cytosol compared to unstimulated cells. Furthermore, the protective effects of CRE were verified via the observation of reduced NO generation and iNOS expression, and normal insulin-secretion responses to glucose in IL-1beta and IFN-gamma-treated islets. 相似文献
65.
Choi JH Park JG Jeon HJ Kim MS Lee MR Lee MN Sonn S Kim JH Lee MH Choi MS Park YB Kwon OS Jeong TS Lee WS Shim HB Shin DH Oh GT 《Experimental & molecular medicine》2011,43(8):471-478
A variety of benzylidenethiazole analogs have been demonstrated to inhibit 5-lipoxygenase (5-LOX). Here we report the anti-atherogenic potential of 5-(4-hydroxy- 2,3,5-trimethylbenzylidene) thiazolidin-2,4-dione (HMB-TZD), a benzylidenethiazole analog, and its potential mechanism of action in LDL receptor-deficient (Ldlr-/-) mice. HMB-TZD Treatment reduced leukotriene B4 (LTB4) production significantly in RAW264.7 macrophages and SVEC4-10 endothelial cells. Macrophages or endothelial cells pre-incubated with HMB-TZD for 2 h and then stimulated with lipopolysaccharide or tumor necrosis factor-alpha (TNF-α) displayed reduced cytokine production. Also, HMB-TZD reduced cell migration and adhesion in accordance with decreased proinflammatory molecule production in vitro and ex vivo. HMB-TZD treatment of 8-week-old male Ldlr-/- mice resulted in significantly reduced atherosclerotic lesions without a change to plasma lipid profiles. Moreover, aortic expression of pro-atherogenic molecules involved in the recruitment of monocytes to the aortic wall, including TNF-α , MCP-1, and VCAM-1, was downregulated. HMB-TZD also reduced macrophage infiltration into atherosclerotic lesions. In conclusion, HMB-TZD ameliorates atherosclerotic lesion formation possibly by reducing the expression of proinflammatory molecules and monocyte/macrophage recruitment to the lesion. These results suggest that HMB-TZD, and benzylidenethiazole analogs in general, may have therapeutic potential as treatments for atherosclerosis. 相似文献
66.
A highly sensitive nanomechanical cantilever sensor assay based on an electrical measurement has been developed for detecting activated cyclic adenosine monophosphate (cyclic AMP)-dependent protein kinase (PKA). Employing a peptide derived from the heat-stable protein kinase inhibitor (PKI), a magnetic bead system was first selected as a vehicle to immobilize the PKI-(5-24) peptide for capturing PKA catalytic subunit and the activity assay was applied for indirectly assessing the binding. Synergistic interactions of adenosine triphosphate (ATP) and the peptide inhibitor with the kinase were then investigated by a solution phase capillary electrophoretic assay, and by surface plasmon resonance technology which involved immobilization of the peptide inhibitor. After systemically evaluated by a homogeneous direct binding assay, the ATP-dependent recognition of the catalytic subunit of PKA by PKI-(5-24) was successfully transferred on to the nanomechanical cantilevers at protein concentrations of 6.6 pM-66 nM, exhibiting much higher sensitivity and wider dynamic range than the conventional activity assay. Thus, direct assessment of activated kinases using the cantilever sensor system functionalized with specific peptide inhibitors holds great promise in analytical applications and clinical medicine. 相似文献
67.
Tamanna Sultana Jae Mok Jung Seong-Soo Hong Won-Ki Lee Yeong-Soon Gal Hyun Gyu Kim Kwon Taek Lim 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(1-2):207-212
Inclusion properties of the drug omeprazole (OMP) with peracetylated-beta-cyclodextrin (PAc-β-CD) prepared by green method, following supercritical carbon-dioxide (scCO2), were characterized through thermal (TGA and DSC), crystalline (XRD), NMR spectroscopic and dissolution studies. Comparison amongst PAc-β-CD, OMP, physical binary mixture (equimolar ratio of OMP: PAc-β-CD) and the solid inclusion complex (OMP/PAc-β-CD) revealed scCO2 as a successful technique for inclusion complex formation as well, identified characteristics performances of PAc-β-CD/OMP interactions. For instance, absence of characteristic DSC or XRD peaks of either chemical in the complex was quite noticeable with the shift of proton peaks in 1H NMR spectra. The formed inclusion complex also showed an important dissolution performance of OMP for controlled release applications partly due to the hydrophobic nature of PAc-β-CD. 相似文献
68.
An efficient and eco-friendly procedure for the synthesis of 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carboxamide has been developed through a one-pot three-component condensation of 4-hydroxycoumarin with aldehydes and cyanoacetamide, in the presence of catalytic amount of polystyrene-supported p-toluenesulfonic acid (PS-PTSA) as a highly active and reusable heterogeneous acid catalyst in EtOH at 80?°C conditions. This new procedure offers several advantages such as shorter reaction times, excellent yields, a wide range of functional group tolerance, easy experimental work-up procedure, operationally simple under metal-free reaction conditions and C-C/C-O bond formation. The catalyst can be recovered and reused for at least four runs without any significant impact on the product yields. 相似文献
69.
70.