全文获取类型
收费全文 | 82篇 |
免费 | 3篇 |
国内免费 | 7篇 |
专业分类
92篇 |
出版年
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2016年 | 1篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1974年 | 2篇 |
排序方式: 共有92条查询结果,搜索用时 15 毫秒
41.
Hena Khanam Ashraf Mashrai Asif Sherwani Mohammad Owais Nazish Siddiqui 《Steroids》2013,78(12-13):1263-1272
The synthesis and anti-tumor activity screening of new steroidal derivatives (4–18) containing pharmacologically attractive pyrazoline moieties are performed. During in vitro anticancer evaluation, the newly synthesized compounds displayed moderate to good cytotoxicity on cervical and leukemia cancer cell lines. In addition these compounds were found to be nontoxic to normal cell (PBMCs) (IC50 > 50 μM). The structure–activity relationship is also discussed. The most effective anticancer compound 9 was found to be active with IC50 value of 10.6 μM. It demonstrated significant antiproliferative influence on Jurkat cell lines. The morphological changes and growth characteristics of HeLa cells treated with compound 4 were analyzed by means of SEM. 相似文献
42.
José M. GUERRA-GARC 《动物学报》2007,53(1):179-183
铁锈笠螺是地中海最濒危的海洋无脊椎动物,对其生物学知之甚少,缺少对其活动节律和采食行为的了解。使用环氧树脂Eporai1127(原位标记了20个不同外壳长度的个体,并在每个外壳上标有不同的数字,作者在白昼或黑夜的高潮和低潮期收集了有关数据。可能由于云斑厚纹蟹(Pachygrapsus marmoratus)的捕食影响,铁锈笠螺白天的活动和运动多于夜间,但铁锈笠螺采食行为似乎仅限于高潮期。此外,汹涌的海面条件诱导了铁锈笠螺的活动和运动。 相似文献
43.
Jennifer FA Swisher Devin A Haddad Anna G McGrath Gunther H Boekhoudt Gerald M Feldman 《MABS-AUSTIN》2014,6(6):1377-1384
Antibodies evoke cellular responses through the binding of their Fc region to Fc receptors, most of which contain immunoreceptor tyrosine-based activation motif domains and are thus considered “activating.” However, there is a growing appreciation of these receptors for their ability to deliver an inhibitory signal as well. We previously described one such phenomenon whereby interferon (IFN)γ signaling is inhibited by immune complex signaling through FcγRI. To understand the implications of this in the context of therapeutic antibodies, we assessed individual IgG subclasses to determine their ability to deliver this anti-inflammatory signal in monocyte-derived macrophages. Like IgG1, we found that IgG4 is fully capable of inhibiting IFNγ-mediated events. In addition, F(ab’)2 fragments that interfere with FcγRI signaling reversed this effect. For mAbs developed with either an IgG1 or an IgG4 constant region for indications where inflammation is undesirable, further examination of a potential Fc-dependent contribution to their mechanism of action is warranted. 相似文献
44.
Lazos-Monterrosa FA C Orantes-García O Farrera-Sarmiento AG Verdugo-Valdez MS Sánchez-Cortés LE Ruíz-Meza 《Phyton》2015,84(1):138-143
The tempisque (Sideroxylon capiri) is a tree native to Mexico used by the rural population for housing construction, poles and hedges, as fuel (wood) and also for fodder and ornamental purposes, among others. It is considered an endangered species. In order to contribute to its preservation and sustainable management, it was considered important to determine the proportion of viable seeds, the loss of viability due to storage period and the germination process by applying pregerminative treatments. We found that freshly collected seeds showed 100% viability, which decreased to 0% after 5 months of storage. According to the cumulative germination significant differences between treatments (p≤0.01) were found. It was observed that seeds can accelerate their time of germination with the previous exposure of 24 h in water at room temperature. The soaking treatment in water for 24 h at room temperature obtained final germination of 55%, while with the control 39% was reached. Soaking in hydrogen peroxide and scarification were the treatments with lower germination percentage (33 and 23%, respectively). To get a higher percentage of germinated seeds in a short time, it is necessary to give a soaking treatment in water for 24 h before sowing. 相似文献
45.
46.
Prenatal maternal psychological distress increases risk for adverse infant outcomes. However, the biological mechanisms underlying this association remain unclear. Prenatal stress can impact fetal epigenetic regulation that could underlie changes in infant stress responses. It has been suggested that maternal glucocorticoids may mediate this epigenetic effect. We examined this hypothesis by determining the impact of maternal cortisol and depressive symptoms during pregnancy on infant NR3C1 and BDNF DNA methylation. Fifty-seven pregnant women were recruited during the second or third trimester. Participants self-reported depressive symptoms and salivary cortisol samples were collected diurnally and in response to a stressor. Buccal swabs for DNA extraction and DNA methylation analysis were collected from each infant at 2 months of age, and mothers were assessed for postnatal depressive symptoms. Prenatal depressive symptoms significantly predicted increased NR3C1 1F DNA methylation in male infants (β = 2.147, P = 0.044). Prenatal depressive symptoms also significantly predicted decreased BDNF IV DNA methylation in both male and female infants (β = −3.244, P = 0.013). No measure of maternal cortisol during pregnancy predicted infant NR3C1 1F or BDNF promoter IV DNA methylation. Our findings highlight the susceptibility of males to changes in NR3C1 DNA methylation and present novel evidence for altered BDNF IV DNA methylation in response to maternal depression during pregnancy. The lack of association between maternal cortisol and infant DNA methylation suggests that effects of maternal depression may not be mediated directly by glucocorticoids. Future studies should consider other potential mediating mechanisms in the link between maternal mood and infant outcomes. 相似文献
47.
梨头霉11α—羟基化制备16β—甲基—11α,17α21—三烃基孕甾—1, … 总被引:1,自引:2,他引:1
选育到一株对16β-甲基-17α,21-二羟基孕甾-1,4=-二烯-3,20-二酮(Ⅱa)11α-羟基化活性强的梨头霉A28菌株,并发现底物21-乙酰化(Ⅱb)可明显提高11α-羟工 能力。在适宜的转化条件下,11b投料浓度0.5%,产物16β-基11α,17α,21-三羟基孕甾-1,4-二烯-3,20-二酮(Ⅲ)收率为73%,结构经波谱分析确认。 相似文献
48.
Yasser AbdElsattar Elghobashy Mohamed FA. Assar Asmaa A. Mahmoud Abdel Monem A Eltorgoman Saher Elmasry 《Biochemistry and Biophysics Reports》2020
Backgroundβ-thalassemia is an inherited hemoglobinopathy resulting in quantitative changes in the β-globin chain. Understanding the molecular basis of that disorder requires studying the expression of genes controlling the pathways that affect the erythropoietic homeostasis especially the MAPK pathway. The MAPKs are a family of serine/threonine kinases that play an essential role in connecting cell-surface receptors to DNA in the nucleus of the cell.Aimto study the effect of expression of GNAI2, DUSP5 and ARRB1 genes on MAPK signaling pathway in pediatric patients with beta thalassemia.MethodsForty children with beta thalassemia major (TM), forty children with beta thalassemia intermedia (TI) and forty age and gender matched healthy controls were enrolled in this study. Detection of GNAI2, DUSP5 and ARRB1 mRNA expression was done by real time polymerase chain reaction (RT-PCR).Resultsrevealed increased expression of ARRB1 (Arrestin Beta 1) gene, and decreased expression of both GNAI2 (Guanine nucleotide-binding protein G (i) subunit alpha-2) and DUSP5 (Dual specificity protein phosphatase 5) genes in both patient groups than control groups respectively.ConclusionsChange in the rate of expression of ARRB1, GNAI2 and DUSP5 may have a role in the pathogenesis of abnormal hematopoiesis in cases of β thalassemia through affecting the MAPK pathway. 相似文献
49.
50.
敦煌西湖湿地鸟类栖息地重要性模糊综合评判 总被引:3,自引:1,他引:3
根据2007~2008年在甘肃敦煌西湖国家级自然保护区进行的湿地鸟类调查种类和数量数据,运用模糊综合评判法对保护区内的8块湿地进行了湿地鸟类栖息地重要性评价. 评判中隶属度的确定采用最佳因子值法,并分春、秋两种最佳因子值进行评判.结果表明:(1)春季各湿地均比秋季的重要性程度高,春季是管理的重点;(2)春秋两季南湖湿地重要性(0.938和0.966)都要远大于其它的湿地.春季盐池湾、羊水海子、南大湖的结果较相近,重要性程度次之,可持有相同程度的管理水平.党河水库、墩子湾、马圈湾、南园湖的重要性程度较低,只需一般水平的管理;(3)秋季各湿地水平除了南湖外普遍较低,羊水海子和盐池湾的重要性(0.340和0.269)相对较高些,但也只需一般水平的管理. 相似文献