全文获取类型
收费全文 | 731篇 |
免费 | 56篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 10篇 |
2020年 | 5篇 |
2019年 | 15篇 |
2018年 | 11篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 24篇 |
2014年 | 26篇 |
2013年 | 57篇 |
2012年 | 47篇 |
2011年 | 57篇 |
2010年 | 38篇 |
2009年 | 39篇 |
2008年 | 49篇 |
2007年 | 43篇 |
2006年 | 45篇 |
2005年 | 43篇 |
2004年 | 27篇 |
2003年 | 36篇 |
2002年 | 31篇 |
2001年 | 15篇 |
2000年 | 10篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 10篇 |
1991年 | 3篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1968年 | 2篇 |
1966年 | 2篇 |
1920年 | 1篇 |
排序方式: 共有787条查询结果,搜索用时 187 毫秒
61.
62.
Ishii M Jorge SD de Oliveira AA Palace-Berl F Sonehara IY Pasqualoto KF Tavares LC 《Bioorganic & medicinal chemistry》2011,19(21):6292-6301
A series of 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazole derivatives was synthesized and their activity screened in vitro against Staphylococcus aureus, Trypanosoma cruzi, and Candida albicans. The bioactivity was expressed as minimum inhibitory concentration (MIC) for S. aureus strains, and as fifty-percent inhibitory concentration (IC(50)) of parasite population growth for T. cruzi. A molecular modeling approach was performed to establish qualitative relationships regarding the biological data and the compounds' physicochemical properties. The 5-(4-OC(4)H(9)Ph, 5l), and 5-(4-CO(2)CH(3)Ph, 5o) derivatives were the most active compounds for S. aureus ATCC 25923 (MIC=1.95-1.25 μg/mL) and T. cruzi (IC(50)=7.91 μM), respectively. Also, a preliminary evaluation against C. albicans involving some compounds was performed and the 5-(4-CH(3)Ph, 5e) derivative was the most active compound (MIC=3.28-2.95 μg/mL). In this preliminary study, all synthesized 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazole derivatives were active against all microorganisms tested. 相似文献
63.
64.
65.
Morimoto T Kojima Y Toki T Komeda Y Yoshiyama M Kimura K Nirasawa K Kadowaki T 《Ecology and evolution》2011,1(2):201-217
The honey bee is a major insect used for pollination of many commercial crops worldwide. Although the use of honey bees for pollination can disrupt the habitat, the effects on their physiology have never been determined. Recently, honey bee colonies have often collapsed when introduced in greenhouses for pollination in Japan. Thus, suppressing colony collapses and maintaining the number of worker bees in the colonies is essential for successful long-term pollination in greenhouses and recycling of honey bee colonies. To understand the physiological states of honey bees used for long-term pollination in greenhouses, we characterized their gene expression profiles by microarray. We found that the greenhouse environment changes the gene expression profiles and induces immune-suppression and oxidative stress in honey bees. In fact, the increase of the number of Nosema microsporidia and protein carbonyl content was observed in honey bees during pollination in greenhouses. Thus, honey bee colonies are likely to collapse during pollination in greenhouses when heavily infested with pathogens. Degradation of honey bee habitat by changing the outside environment of the colony, during pollination services for example, imposes negative impacts on honey bees. Thus, worldwide use of honey bees for crop pollination in general could be one of reasons for the decline of managed honey bee colonies. 相似文献
66.
Takayanagi Y Takahashi T Orikabe L Mozue Y Kawasaki Y Nakamura K Sato Y Itokawa M Yamasue H Kasai K Kurachi M Okazaki Y Suzuki M 《PloS one》2011,6(6):e21047
Background
Although structural magnetic resonance imaging (MRI) studies have repeatedly demonstrated regional brain structural abnormalities in patients with schizophrenia, relatively few MRI-based studies have attempted to distinguish between patients with first-episode schizophrenia and healthy controls.Method
Three-dimensional MR images were acquired from 52 (29 males, 23 females) first-episode schizophrenia patients and 40 (22 males, 18 females) healthy subjects. Multiple brain measures (regional brain volume and cortical thickness) were calculated by a fully automated procedure and were used for group comparison and classification by linear discriminant function analysis.Results
Schizophrenia patients showed gray matter volume reductions and cortical thinning in various brain regions predominantly in prefrontal and temporal cortices compared with controls. The classifiers obtained from 66 subjects of the first group successfully assigned 26 subjects of the second group with accuracy above 80%.Conclusion
Our results showed that combinations of automated brain measures successfully differentiated first-episode schizophrenia patients from healthy controls. Such neuroimaging approaches may provide objective biological information adjunct to clinical diagnosis of early schizophrenia. 相似文献67.
Glycolipids in the thymus of mice after administration of dexamethasone were compared with those in control mice. In parallel with a decrease in the tissue weight due to the disappearance of immature thymocytes in the cortex, the amounts of GlcCer, Gg4Cer and GM1 decreased from 18 h after intraperitoneal administration of dexamethasone, but those of Gb4Cer and Forssman glycolipid did not change, indicating the differential distribution of ganglio- and globo-series glycolipids in the thymus, GlcCer, Gg4Cer and GM1 being on dexamethasone-sensitive cortical thymocytes, and Gb4Cer and Forssman glycolipid on dexamethasone-resistant cells including thymic stromal cells, respectively. At the same time, a characteristic increase in GM3, whose amount per thymus and concentration per mg of thymus were increased 4-fold and 13-fold compared to those in the control mice, respectively, was observed at the onset of the decrease in tissue weight and was due to the increased activity of LacCer sialyltransferase with the enhanced expression of its gene and the concomitant decrease in cytosolic sialidase activity. One can suggest that endogenous accumulation of GM3 is involved in the dexamethasone-induced apoptosis of cortical thymocytes. On radiolabeling of the thymus with CMP-[14C]-NeuAc, the incorporation of radioactivity into GM3 was preferentially observed in the thymuses of dexamethasone-administered mice, but not in those of control mice, suggesting the possible involvement of plasma membrane-associated sialytransferase in GM3 synthesis in the thymuses of dexamethasone-administered mice.
Published in 2005. 相似文献
68.
Tadano M Edamatsu H Minamisawa S Yokoyama U Ishikawa Y Suzuki N Saito H Wu D Masago-Toda M Yamawaki-Kataoka Y Setsu T Terashima T Maeda S Satoh T Kataoka T 《Molecular and cellular biology》2005,25(6):2191-2199
Phospholipase Cepsilon is a novel class of phosphoinositide-specific phospholipase C, identified as a downstream effector of Ras and Rap small GTPases. We report here the first genetic analysis of its physiological function with mice whose phospholipase Cepsilon is catalytically inactivated by gene targeting. The hearts of mice homozygous for the targeted allele develop congenital malformations of both the aortic and pulmonary valves, which cause a moderate to severe degree of regurgitation with mild stenosis and result in ventricular dilation. The malformation involves marked thickening of the valve leaflets, which seems to be caused by a defect in valve remodeling at the late stages of semilunar valvulogenesis. This phenotype has a remarkable resemblance to that of mice carrying an attenuated epidermal growth factor receptor or deficient in heparin-binding epidermal growth factor-like growth factor. Smad1/5/8, which is implicated in proliferation of the valve cells downstream of bone morphogenetic protein, shows aberrant activation at the margin of the developing semilunar valve tissues in embryos deficient in phospholipase Cepsilon. These results suggest a crucial role of phospholipase Cepsilon downstream of the epidermal growth factor receptor in controlling semilunar valvulogenesis through inhibition of bone morphogenetic protein signaling. 相似文献
69.
70.