首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   580篇
  免费   21篇
  国内免费   26篇
  2023年   5篇
  2022年   13篇
  2021年   14篇
  2020年   12篇
  2019年   36篇
  2018年   24篇
  2017年   23篇
  2016年   7篇
  2015年   11篇
  2014年   52篇
  2013年   46篇
  2012年   31篇
  2011年   34篇
  2010年   17篇
  2009年   19篇
  2008年   26篇
  2007年   23篇
  2006年   21篇
  2005年   17篇
  2004年   15篇
  2003年   18篇
  2002年   10篇
  2001年   12篇
  2000年   5篇
  1999年   7篇
  1998年   9篇
  1997年   9篇
  1996年   9篇
  1995年   11篇
  1994年   11篇
  1993年   8篇
  1992年   11篇
  1991年   10篇
  1990年   3篇
  1989年   2篇
  1988年   5篇
  1987年   2篇
  1985年   2篇
  1984年   4篇
  1983年   5篇
  1982年   6篇
  1981年   3篇
  1980年   6篇
  1979年   3篇
  1977年   1篇
  1976年   1篇
  1974年   4篇
  1973年   3篇
  1971年   1篇
排序方式: 共有627条查询结果,搜索用时 0 毫秒
621.
High-speed fluorescence-activated cell sorting is relevant for a plethora of applications, such as PCR-based techniques, microarrays, cloning, and propagation of selected cell populations. We suggest a simple cell-sorting technique to eliminate early and late apoptotic and necrotic cells, with good signal-to-noise ratio and a high-purity yield. The mitochondrial potential dye, TMRE (tetramethylrhodamine ethyl ester perchlorate), was used to separate viable and non-apoptotic cells from the cell sorting samples. TMRE staining is reversible and does not affect cell proliferation and viability. Sorted TMRE+ cells contained a negligible percentage of apoptotic and damaged cells and had a higher proliferative potential as compared with their counterpart cells, sorted on the basis of staining with DNA viability dye. This novel sorting technique using TMRE does not interfere with subsequent functional assays and is a method of choice for the enrichment of functionally active, unbiased cell populations.  相似文献   
622.
The carboxylesterase Notum is a key negative regulator of the Wnt signaling pathway by mediating the depalmitoleoylation of Wnt proteins. Our objective was to discover potent small molecule inhibitors of Notum suitable for exploring the regulation of Wnt signaling in the central nervous system. Scaffold-hopping from thienopyrimidine acids 1 and 2, supported by X-ray structure determination, identified 3-methylimidazolin-4-one amides 2024 as potent inhibitors of Notum with activity across three orthogonal assay formats (biochemical, extra-cellular, occupancy). A preferred example 24 demonstrated good stability in mouse microsomes and plasma, and cell permeability in the MDCK-MDR1 assay albeit with modest P-gp mediated efflux. Pharmacokinetic studies with 24 were performed in vivo in mouse with single oral administration of 24 showing good plasma exposure and reasonable CNS penetration. We propose that 24 is a new chemical tool suitable for cellular studies to explore the fundamental biology of Notum.  相似文献   
623.
IntroductionAblating the slow pathway (SP) is the superior treatment for atrioventricular nodal reentrant tachycardia (AVNRT) with a low complication rate. However, the ablation of the SP could result in either complete elimination or modification of the SP. We aimed to investigate whether the duration of AH jump pre-ablation associated with the outcome of elimination of SP.MethodsWe included 56 patients with typical AVNRT (slow-fast), 20 males and 36 females, aged 44.2 ± 15.1 years. Slow pathway ablation was performed using classical approach. Univariate and multivariate analysis was performed for potential predictors of SP elimination.ResultsTypical AVNRT was inducible in all patients. Post-ablation, non-inducibility of AVNRT was obtained in all 56 (100%) patients, with SP elimination in 33 (61%) patients and SP modification in 23 (39%) patients. Patients with SP elimination had significantly longer AH jump than patients with SP modification. Cox regression analysis showed that AH jump duration was the independent predictor of SP elimination, in which every 20 ms increase in AH jump duration was associated with 1.30 higher rate of SP elimination. Furthermore, ROC curve analysis indicated that the AH jump duration of ≥100 ms had 6.14 times higher probability for complete elimination of the SP with a sensitivity of 79%, specificity of 70%, PPV of 79% and NPV of 70%.ConclusionsAH jump duration pre-ablation is associated with complete elimination of slow pathway during AVNRT ablation.  相似文献   
624.
Nonalcoholic fatty liver disease (NAFLD) is a clinicopathological syndrome characterized by excessive deposition of fatty acids in the liver. Further deterioration leads to nonalcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma, creating a heavy burden on human health and the social economy. Currently, there are no effective and specific drugs for the treatment of NAFLD. Therefore, it is important to further investigate the pathogenesis of NAFLD and explore effective therapeutic targets for the prevention and treatment of the disease. Six-transmembrane epithelial antigen of prostate 3 (STEAP3), a STEAP family protein, is a metalloreductase. Studies have shown that it can participate in the regulation of liver ischemia-reperfusion injury, hepatocellular carcinoma, myocardial hypertrophy, and other diseases. In this study, we found that the expression of STEAP3 is upregulated in NAFLD. Deletion of STEAP3 inhibits the development of NAFLD in vivo and in vitro, whereas its overexpression promotes palmitic acid/oleic acid stimulation-induced lipid deposition in hepatocytes. Mechanistically, it interacts with transforming growth factor beta-activated kinase 1 (TAK1) to regulate the progression of NAFLD by promoting TAK1 phosphorylation and activating the TAK1-c-Jun N-terminal kinase/p38 signaling pathway. Taken together, our results provide further insight into the involvement of STEAP3 in liver pathology.  相似文献   
625.
ObjectiveHere, the aim is to improve the bioavailability of Naringenin (NRG) in brain and to establish the highest remedial benefit from a novel anti-ischemic medicine i.e. NRG.MethodsA novel Naringenin-loaded-nanoemulsion (NE)-(in situ)-gel (i.e. thermoresponsive), was formulated with the help of Poloxamer-407 (20.0% w/v). Chitosan (CS, 0.50% w/v) was used to introduce the mucoadhesive property of NE-(in situ)-gel and finally called as NRG-NE-gel + 0.50%CS. A novel UHPLC-ESI-Q-TOF-MS/MS-method was optimized and used for NRG-NE-gel + 0.50%CS to quantify the Pharmacokinetic-(PK)-parameters in plasma as well as brain and to evaluate the cerebral ischemic parameters after MCAO i.e. locomotor activity, grip strength, antioxidant activity, and quantity the infarction volume in neurons with the safety/toxicity of NRG-NE-gel + 0.50%CS after i.n. administration in the rats.ResultsThe mucoadhesive potency and gelling temperature of NRG-NE-gel + 0.50%CS were observed 6245.38 dynes/cm2 and 28.3 ± 1.0 °C, respectively. Poloxamer-407 based free micelles size was observed 98.31 ± 1.17 nm with PDI (0.386 ± 0.021). The pH and viscosity of NRG-NE-gel + 0.50%CS were found to be 6.0 ± 0.20 and 2447 ± 24cp (at 35.0 ± 1.0 °C temperature), respectively. An elution time and m/z NRG were observed 1.78 min and 270.97/150.96 with 1.22 min and m/z of 301.01/150.98 for Quercetin (IS) respectively. Inter and intra %precision and %accuracy was validated 1.01–3.37% and 95.10–99.30% with a linear dynamic range (1.00 to 2000.00 ng/ml). AUC0-24 of plasma & brain were observed 995.60 ± 24.59 and 5600.99 ± 144.92 (ng min/ml g) in the rats after the intranasal (i.n.) administration of NRG-NE-gel + 0.50%CS. No toxicological response were not found in terms of mortalities, any-change morphologically i.e. in the microstructure of brain as well as nasal mucosa tissues, and also not found any visual signs in terms of inflammatory or necrosis.ConclusionIntranasally administered NRG-NE-gel + 0.50%CS enhanced the bioavailability of Naringenin in the brain. In the cerebral ischemic rats, significantly improved the neurobehavioral activity (locomotor & grip strength) followed by antioxidant activity as well as infarction volume. Finally, the toxicity studies carried out and established the safe nature of optimized-NRG-NE-gel + 0.50%CS.  相似文献   
626.
Summary An interspecific hybrid between Hordeum chilense and H. bulbosum was produced. The hybrid resembles the male parent, but some characters from H. chilense are also present. Transgressive inheritance for other characters has also been observed. Neither chromosome instability nor homoeologous pairing was found.  相似文献   
627.
The neural network underlying rhythmic wing movements in the molluscClione limacina is well-studied. Two different groups of motoneurons innervate two distinct groups of wing muscles. The locomotor rhythm generated in the left and right pedal ganglia is synchronized by interneurons. When the axons of the locomotor motoneurons are crushed, numerous fine neurites sprout towards the denervated muscles and reach them in 8–15 days. At this stage motoneurons project to and synapse on not only correct but equally incorrect muscle targets. After 2 weeks of regeneration the number of incorrect neurites and synaptic connections begins to decrease and following 1.5–2 months all incorrect connections are eliminated, incorrect axons are withdrawn and the behavioral deficit is compensated. In this study the regeneration of interneurons and the growth profiles of inter- and motoneurons were also studiedin vitro. Two individually isolated pedal ganglia were co-cultured in three different configurations: a) the wing nerve stump from one ganglion was fixed against the commissural stump from another ganglion; b) the wing nerve stumps were fixed against each other; c) the commissural stumps were fixed against each other. Under the above experimental conditions we found that the interneurons were able to cross only the contact between two commissural stumps, and in this case found their original targets, restored correct connections and synchronized the rhythm in two pedal ganglia. In contrast, motoneurons were able to cross all types of contacts.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号