全文获取类型
收费全文 | 410篇 |
免费 | 17篇 |
专业分类
427篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 35篇 |
2014年 | 30篇 |
2013年 | 32篇 |
2012年 | 37篇 |
2011年 | 35篇 |
2010年 | 24篇 |
2009年 | 15篇 |
2008年 | 20篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 14篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有427条查询结果,搜索用时 0 毫秒
1.
This study was designed to localize transforming growth factor alpha (TGF-) and epidermal growth factor receptor (EGFR) expression in the developing human gastrointestinal tract and pancreas. Immunohistochemical techniques using specific antibodies against human TGF- and EGFR were performed on digestive tissues of fetuses from 9 to 10 to 24 weeks of gestation, children and adults. In fetuses, TGF- and EGFR proteins were expressed in all epithelial tissues studied with a good correlation and from an age as early as 9 to 10 weeks of gestation, except for TGF- in the esophagus. The strongest TGF- immunostaining was noted in the stomach and the proximal colon. Unexpectedly, immunoreactive gut endocrine cells were observed with the two antibodies used. Relatively numerous in fetuses, they decreased in number with age and were rare in adults particularly along the colon. Enteroglucagon-secreting cells were shown to express TGF- while some gastrin, somatostatin and pancreatic glucagon cells were immunostained with EGFR antibodies. The presence of TGF- and of its recetor in digestive tract epithelium and pancreatic tissues early in fetal life suggests a functional role for TGF- during the developmental process of the digestive system. We demonstrate that TGF- is also produced by endocrine cells and might have an additional mode of action other than paracrine, at least during fetal life. 相似文献
2.
Souad El Hafidi Khadija Bakhy Mohammed Ouhssine Abderrahim Benzakour Hamid Khamar Joseph Casanova Mathieu Paoli Félix Tomi 《化学与生物多样性》2023,20(1):e202201022
Cladanthus scariosus (Ball) Oberpr. & Vogt is endemic to Moroccan High Atlas. It is known under the vernacular names Irezghi or Irezgui. Three essential oil samples have been isolated from aerial parts and analyzed by combination of chromatographic and spectroscopic techniques [gas chromatography (GC) in combination with retention indices (RI), gas chromatography-mass spectrometry (GC/MS) and 13C-NMR spectroscopy]. The compositions of oil samples were dominated by monoterpenes: α-pinene sabinene, and terpinen-4-ol. Chamazulene and dihydrochamazulene isomers as well as various hemiterpene esters and analogs have been identified. To evidence a chemical variability, statistical analysis performed on 13 oil sample compositions allowed partitioning into three groups, mainly differentiated by their contents of sabinene, camphor, borneol, terpinen-4-ol, and germacrene D. 相似文献
3.
Imane Nait Irahal Dounia Darif Ismail Guenaou Fouzia Hmimid Fatima azzahra Lahlou Fatima Ez-zahra Ousaid Fatima Abdou-Allah Lamiaa Aitsi Khadija Akarid Noureddine Bourhim 《化学与生物多样性》2023,20(3):e202201169
Type 1 diabetes is characterized by insulin deficiency due to the destruction of pancreatic β cells, leading to hyperglycemia, which in turn induces vascular complications. In the current study, we investigated the effect of intraperitoneal administration of clove essential oil (CEO: 20 mg/kg body weight) on certain oxidative stress and glucose metabolism enzymes, as well as the expression of proinflammatory mediators. Administration of CEO to diabetic rats showed a significant decline in blood glucose levels, total cholesterol, and xanthine oxidase, compared to the streptozotocin group. Furthermore, these treated rats elicited a notable attenuation in the levels of lipid peroxides, and thiols groups in both liver and brain tissues. The activities of antioxidant and metabolic enzymes were reverted to normality in diabetic upon CEO administration. In addition to its protective effects on red blood cell hemolysis, CEO is a potent α-amylase inhibitor with an IC50=298.0±2.75 μg/mL. Also, treatment of diabetic rats with CEO significantly reduced the iNOS expression in the spleen. Our data showed that CEO has potential beneficial effects on diabetes, which can possibly prevent the pathogenesis of diabetic micro- and macrovascular complications. 相似文献
4.
B J Stoll R I Glass H Banu M I Huq M U Khan M Ahmed 《BMJ (Clinical research ed.)》1983,286(6383):2037-2040
Findings of stool examinations in 1593 patients with diarrhoea due to a single enteric pathogen--enterotoxigenic Escherichia coli rotavirus, Shigella, Campylobacter jejuni, Vibrio cholerae 0:1, Entamoeba histolytica, or Giardia lamblia--were reviewed to determine how well they predicted the agent associated with the diarrhoea. Specimens were examined visually for blood and mucus, tested for pH, and examined under a microscope for the presence of red and white blood cells, parasites, and stool fat. Although visible blood was more common in specimens from patients infected with Shigella (51%) and Ent histolytica (39%) than in those from patients infected with other agents (6%; p less than 0.01), patients infected with Shigella were most likely to have numerous faecal leucocytes (greater than 50/high power field: 39% v 8% of all patients and 7% of patients infected with Ent histolytica, p less than 0.01 in both cases). Patients infected with enterotoxigenic E coli, rotavirus, V cholerae 0:1, or C jejuni had loose stools with fewer red or white cells. Patients infected with rotavirus and C jejuni were more likely to have acid stools with 3 to 4+ fat, but these findings were related to young age and breast feeding. Stool examination is most useful in establishing a diagnosis of dysentery and in helping to distinguish between patients infected with Shigella and Ent histolytica; it is of limited usefulness in discriminating between pathogens causing watery diarrhoea. 相似文献
5.
M J Banu K Nellaiappan S Dhandayuthapani 《Japanese journal of medical science & biology》1992,45(3):137-150
Mitochondrial malate dehydrogenase (mMDH) and malic enzyme (mME) of a filarial worm Setaria digitata were studied. mMDH exhibited the highest activities in the oxidation and reduction reactions at pH 9.5 and pH 6.2, respectively, while mME did so in the malate decarboxylation reaction at pH 6.8. mME showed no detectable activity on the pyruvate carboxylation direction. The Km values for malate (1.7 mM) and oxaloacetate (0.17 mM) and the ratio of Vmax oxidation: Vmax reduction (2.73) tend to favor the oxaloacetate reduction by mMDH. mME showed a relatively high Km value of 8.3 mM, for malate decarboxylation. A drug, diethylcarbamazine citrate (DEC-C), did not change appreciably the activity of either mMDH or mME, while filarin (a drug of herbal origin) effectively inhibited mMDH. The leaf extracts of Ocimum sanctum, Lawsonia inermis and Calotropis gigantea and leaf and flower extracts of Azadirachta indica were, however, found to inhibit both mMDH and mME. 相似文献
6.
Anlar B Gunel-Ozcan A 《The international journal of biochemistry & cell biology》2012,44(9):1385-1389
Tenascin-R (TN-R), a member of the tenascin family of extracellular matrix glycoproteins, is exclusive to the nervous system. It affects cell migration, adhesion and differentiation, although no remarkable clinical consequences have been shown in knock-out animal models. TN-R's expression pattern suggests a possible primary or secondary role in certain neurological problems including malformations, tumors and neurodegenerative disorders. This review summarizes the structure and molecular interactions of this molecule and discusses its function and possible roles in the central nervous system. 相似文献
7.
Waqar Ahmad Bushra Ijaz Khadija Shabbiri Fayyaz Ahmed Sidra Rehman 《Journal of biomedical science》2017,24(1):76
Reactive oxidative species (ROS) toxicity remains an undisputed cause and link between Alzheimer’s disease (AD) and Type-2 Diabetes Mellitus (T2DM). Patients with both AD and T2DM have damaged, oxidized DNA, RNA, protein and lipid products that can be used as possible disease progression markers. Although the oxidative stress has been anticipated as a main cause in promoting both AD and T2DM, multiple pathways could be involved in ROS production. The focus of this review is to summarize the mechanisms involved in ROS production and their possible association with AD and T2DM pathogenesis and progression. We have also highlighted the role of current treatments that can be linked with reduced oxidative stress and damage in AD and T2DM. 相似文献
8.
9.
Mycopathologia - Dermatophytes are ascomycetous fungi whose sexuality is greatly influenced by their ecology. Sexual reproduction is ubiquitous among soil-related geophiles and some... 相似文献
10.
Despina Soteriou Banu Iskender Adam Byron Jonathan D. Humphries Simon Borg-Bartolo Marie-Claire Haddock Melissa A. Baxter David Knight Martin J. Humphries Susan J. Kimber 《The Journal of biological chemistry》2013,288(26):18716-18731
Human embryonic stem cells (hESCs) are pluripotent cells that have indefinite replicative potential and the ability to differentiate into derivatives of all three germ layers. hESCs are conventionally grown on mitotically inactivated mouse embryonic fibroblasts (MEFs) or feeder cells of human origin. In addition, feeder-free culture systems can be used to support hESCs, in which the adhesive substrate plays a key role in the regulation of stem cell self-renewal or differentiation. Extracellular matrix (ECM) components define the microenvironment of the niche for many types of stem cells, but their role in the maintenance of hESCs remains poorly understood. We used a proteomic approach to characterize in detail the composition and interaction networks of ECMs that support the growth of self-renewing hESCs. Whereas many ECM components were produced by supportive and unsupportive MEF and human placental stromal fibroblast feeder cells, some proteins were only expressed in supportive ECM, suggestive of a role in the maintenance of pluripotency. We show that identified candidate molecules can support attachment and self-renewal of hESCs alone (fibrillin-1) or in combination with fibronectin (perlecan, fibulin-2), in the absence of feeder cells. Together, these data highlight the importance of specific ECM interactions in the regulation of hESC phenotype and provide a resource for future studies of hESC self-renewal. 相似文献