全文获取类型
收费全文 | 474篇 |
免费 | 20篇 |
专业分类
494篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 22篇 |
2020年 | 9篇 |
2019年 | 18篇 |
2018年 | 21篇 |
2017年 | 10篇 |
2016年 | 25篇 |
2015年 | 23篇 |
2014年 | 21篇 |
2013年 | 33篇 |
2012年 | 43篇 |
2011年 | 46篇 |
2010年 | 24篇 |
2009年 | 26篇 |
2008年 | 29篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 21篇 |
2004年 | 23篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
排序方式: 共有494条查询结果,搜索用时 0 毫秒
71.
72.
Caliş I Kirmizibekmez H Tasdemir D Sticher O Ireland CM 《Zeitschrift für Naturforschung. C, Journal of biosciences》2002,57(7-8):591-596
From the methanolic extract of the underground parts of Globularia orientalis, a new antioxidant sugar ester was isolated. The structure of the new compound, globularitol (1), was identified as 6-O-feruloyl-beta-D-glucopyranosyl-(1-->6)-glucitol by spectroscopic methods (1D and 2D NMR, ESI- and FAB-MS) and confirmed by chemical means. 相似文献
73.
Several recent studies have revealed a wide role for nitric oxide (NO) in bone metabolism. Low doses of NO cause bone resorption, but higher doses of NO inhibit bone resorbing activity. Cytokines are potent stimulators of NO production. NO is a very short-lived molecules. It exists for only 6-10 s only before it is converted by oxygen and water into the end-products nitrates and nitrites. Osteoporosis is a metabolic bone disease, characterized by a decreased amount of bone and increased susceptibility to fracture. NO may be involved as a mediator of bone disease such as post-menopausal osteoporosis. Calcitonin is a peptide hormone that inhibits bone resorption. The function of calcitonin in some cells is often unclear. In this study 30 post-menopausal osteoporotic women of ages ranging between 55 and 59 years without systemic diseases and free of any drug therapy were included. Twenty of them, randomly chosen, were treated with calcium (500 mg day(-1))+calcitonin (nasal spray 100 U day(-1)) and the other 10 women (control group) were treated with calcium only. This treatment was applied for 6 months and NO values were measured in each of the two groups before and after treatment. Our findings demonstrate that NO regulates osteoclastic bone resorption activity in association with calcitonin. 相似文献
74.
75.
76.
Pelin Aribal Kocatürk M. Cenk Akbostanci Canan Işikay Aylin Öcal Deniz Tuncel Güzin Özelçi Kavas Nermin Mutluer 《Biological trace element research》2001,80(2):115-124
Ischemia is associated with the pathological changes caused by the accumulation of reactive oxygen metabolites (ROM) in cerebrovascular
accident (CVA). The aim of this study was to determine red cell copper/zinc-superoxide dismutase (Cu/Zn-SOD) and catalase
activities and copper and zinc concentrations both in plasma and in red cells in CVA. Cu/Zn-SOD and catalase activities of
16 patients, with an average age of 64 yr, were measured spectrophotometrically; copper and zinc concentrations were determined
by atomic absorption spectrophotometer. The results showed that Cu/Zn-SOD activity was increased markedly in patients compared
to the young controls and reached a peak on the d 5 of the disease, whereas the catalase activity of the patients on d 3 and
d 5 were in the normal range, but higher on d 10. The enzyme activities of the elderly group were generally increased compared
to the young controls. Copper and zinc concentrations showed corresponding alterations. These findings suggested that the
effects of oxidative stress in CVA might be reflected in red cell and plasma parameters.
Presented at the III International Congress of Pathophysiology, Lahti, Finland, 28 June–3 July, 1998. 相似文献
77.
Park B Nguyen NT Dutt P Merdek KD Bashar M Sterpetti P Tosolini A Testa JR Toksoz D 《The Journal of biological chemistry》2002,277(47):45361-45370
78.
AbstractImmobilization of enzymes from different sources on various supports in designed systems increases enzymes’ stability by protecting the active site of it from undesired effect of reaction environment. Also, immobilization decreases the cost of separation and facilities the reuse of the enzymes. Therefore, the design of new immobilization enzyme preparations has been an inevitable area of modern biotechnology. Herein, Rhizomucor miehei lipase (RML) was immobilized on montmorillonite K-10 (MMT-RML) by adsorption and in polyvinyl alcohol (PVA-RML) by entrapment to obtain a more stable and active lipase preparation. The free and immobilized lipase preparations were characterized for p-nitrophenyl palmitate hydrolysis. The apparent Michaelis–Menten (Kmapp) constant was almost the same for the free RML and PVA-RML, whereas the corresponding value was 17.7-fold lower for MMT-RML. PVA-RML and MMT-RML have shown a 1.1 and 23.8 folds higher catalytic efficiency, respectively, than that of the free RML. The half-lives of PVA-RML and MMT-RML were found to be 7.4 and 3.4 times longer than the free RML at 35?°C, respectively. PVA-RML and MMT-RML maintained 65% and 87% of their initial activities after four reuses. These results showed that the catalytic performance of RML has improved significantly by immobilization. 相似文献
79.
Pomatoschistus anatoliae sp. n. is described from estuary of Göksu River on the Mediterranean coast of the Anatolia. It is distinguished from its congeners by the suborbital papilla pattern, meristic, and ecological features. DNA barcoding based on COI sequences revealed that there is a high nucleotide sequence divergence to the nearest neighbour. Kimura’s two parameter distances between P. anatoliae sp. n. and other species of Pomatoschistus and Knipowitchia have found to be at least 5.1%.
http://www.zoobank.org/urn:lsid:zoobank.org:pub:4592CF50-07B5-4C25-892F-5D009057675B 相似文献
80.
Deniz Kanca Uzay Gormus Bengu Tokat Allison P. Eronat Zehra Bugra Oğuz Ozturk Hulya Yilmaz-Aydogan 《Biochemical genetics》2017,55(2):168-182
Recently, subfraction analysis of serum low density lipoprotein (LDL) is considered to be a better predictor of the risk of coronary heart disease (CHD) compared to the other lipid parameters. The aim of this study was to examine the effects of the HDL-associated Taq1B (rs708272) SNP of cholesterol ester transfer protein (CETP) gene on serum LDL subfractions in patients with CHD. Serum lipid levels were measured enzymatically and LDL subfraction analysis was carried out by the Lipoprint System (Quantimetrix, CA, USA). The CETP rs708272 SNP was studied in 66 healthy controls and 79 patients with CHD receiving statin therapy by the PCR–RFLP technique. The CHD patients had elevated antiatherogenic LDL-1 subfraction (p = 0.042), decreased atherogenic IDL-C subfraction (p = 0.023), and total IDL (p = 0.030) levels compared to the healthy controls. The CETP rs708272 Taq1B minor B2 allele was associated with increased levels of antiatherogenic LDL-1 (B2: 0.40 ± 0.20 vs. B1B1: 0.25 ± 0.08, p = 0.004) and large-LDL (LDL 1–2) subfractions in the CHD group (B2 allele: 0.68 ± 0.41 vs. B1B1: 0.42 ± 0.20; p < 0.05), while it was associated with reduced levels of the large-LDL subfraction in healthy subjects (B2 allele: 0.29 ± 0.14 vs. B1B1: 0.54 ± 0.24; p = 0.017). However, there was no statistically significant association between the CETP rs708272 SNP and small dense LDL subfraction (LDL 3–7) and lipoprotein levels (p > 0.05). Our findings have indicated that the CETP rs708272 SNP together with statin therapy may show a favorable effect on antiatherogenic LDL-1 and large-LDL subfractions in CHD patients with an atherogenic effect on large-LDL subfraction in healthy subjects. Based on these results, it can be concluded that the effects of the CETP variation on LDL subfraction could change in cardiometabolic events such as CHD and statin therapy. 相似文献