全文获取类型
收费全文 | 293篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
300篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 12篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 8篇 |
2014年 | 15篇 |
2013年 | 16篇 |
2012年 | 29篇 |
2011年 | 32篇 |
2010年 | 17篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 13篇 |
2006年 | 16篇 |
2005年 | 22篇 |
2004年 | 17篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有300条查询结果,搜索用时 0 毫秒
21.
22.
Population density, fecundity andreproduction period of Artemia sp. in TuzLake, Turkey, beside environmental factors, such as oxygen,temperature, salinity, pH and electrical conductivity werestudied during 1993 and 1994.Artemia sp. occurred at two stations at the coast.Overwintering cysts hatched in early May, when the population was composed of 90% metanauplii (93%at Y4 and 99% at Y5) and few adult females. Peak abundanceoccurred in late May, at 106to 114 ind.m–3. 相似文献
23.
24.
Fatih Oltulu Duygu Ç. Kocatürk Yasemin Adalı Berrin Özdil Eda Açikgöz Çevik Gürel N. Ulku Karabay Yavasoğlu Huseyin Aktuğ 《Journal of cellular biochemistry》2019,120(10):18066-18076
Embryonic developmental stages and regulations have always been one of the most intriguing aspects of science. Since the cancer stem cell discovery, striking for cancer development and recurrence, embryonic stem cells and control mechanisms, as well as cancer cells and cancer stem cell control mechanisms become important research materials. It is necessary to reveal the similarities and differences between somatic and cancer cells which are formed of embryonic stem cells divisions and determinations. For this purpose, mouse embryonic stem cells (mESCs), mouse skin fibroblast cells (MSFs) and mouse lung squamous cancer cells (SqLCCs) were grown in vitro and the differences between these three cell lines signalling regulations of mechanistic target of rapamycin (mTOR) and autophagic pathways were demonstrated by immunofluorescence and real-time polymerase chain reaction. Expressional differences were clearly shown between embryonic, cancer and somatic cells that mESCs displayed higher expressional level of Atg10, Hdac1 and Cln3 which are related with autophagic regulation and Hsp4, Prkca, Rhoa and ribosomal S6 genes related with mTOR activity. LC3 and mTOR protein levels were lower in mESCs than MSFs. Thus, the mechanisms of embryonic stem cell regulation results in the formation of somatic tissues whereas that these cells may be the causative agents of cancer in any deterioration. 相似文献
25.
The contribution of lateral parietal regions such as the angular gyrus to human episodic memory has been the subject of much debate following widespread observations of left parietal activity in healthy volunteers during functional neuroimaging studies of memory retrieval. Patients with lateral parietal lesions are not amnesic, but recent evidence indicates that their memory abilities may not be entirely preserved. Whereas recollection appears intact when objective measures such as source accuracy are used, patients often exhibit reduced subjective confidence in their accurate recollections. When asked to recall autobiographical memories, they may produce spontaneous narratives that lack richness and specificity, but can remember specific details when prompted. Two distinct theoretical accounts have been proposed to explain these results: that the patients have a deficit in the bottom-up capturing of attention by retrieval output, or that they have an impairment in the subjective experience of recollection. The present study aimed to differentiate between these accounts using continuous theta burst stimulation (cTBS) in healthy participants to disrupt function of specific left parietal subregions, including angular gyrus. Inconsistent with predictions of the attentional theory, angular gyrus cTBS did not result in greater impairment of free recall than cued recall. Supporting predictions of the subjective recollection account, temporary disruption of angular gyrus was associated with highly accurate source recollection accuracy but a selective reduction in participants’ rated source confidence. The findings are consistent with a role for angular gyrus in the integration of memory features into a conscious representation that enables the subjective experience of remembering. 相似文献
26.
Melatonin and N-acetylcysteine have beneficial effects during hepatic ischemia and reperfusion 总被引:18,自引:0,他引:18
Sener G Tosun O Sehirli AO Kaçmaz A Arbak S Ersoy Y Ayanoğlu-Dülger G 《Life sciences》2003,72(24):2707-2718
This study was designed to study the effects of Melatonin (Mel) and N-Acetylcystein (NAC) on hepatic ischemia/reperfusion (I/R) injury in rats. For this purpose Wistar albino rats were subjected to 45 minutes of hepatic ischemia followed by 60 minutes of reperfusion period. Melatonin (10 mg/kg) or NAC (150 mg/kg) were administered alone or in combination, intraperitoneally, 15 minutes prior to ischemia and just before reperfusion. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were determined to assess liver functions. Liver tissues were taken for determination of malondialdehyde (MDA) levels, an end product of lipid peroxidation; glutathione (GSH) levels, a key antioxidant; protein carbonyl concentration (protein oxidation) (PO), a specific marker of oxidative damage of proteins; and myeloperoxidase (MPO) activity, as an indirect index of neutrophil infiltration. Plasma ALT and AST activities were higher in ischemia/reperfusion group than in control. They were decreased in the groups given Mel, NAC or the combination. Hepatic GSH levels, significantly depressed by I/R, were elevated to control levels in the combination group, whereas treatment with Mel or NAC alone provided only a limited protection. Hepatic MDA and PO levels, and MPO activity were significantly increased by I/R. The increase in these parameters were partially decreased by Mel or NAC alone, whereas treatment with the combination reduced these values back to control levels. In conclusion, considering the dosages used, Mel appeared to be significantly more potent than NAC in reversing the oxidative damage induced by I/R. Our findings show that Mel and NAC have beneficial effects against the I/R injury and due to their synergistic effects, when administered in combination, may have a more pronounced protective effects on the liver. 相似文献
27.
28.
Ozsoy O Seval-Celik Y Hacioglu G Yargicoglu P Demir R Agar A Aslan M 《Neurochemistry international》2011,59(5):664-670
This study aimed to investigate the effects of docosahexaenoic acid (DHA) on the oxidative stress that occurs in an experimental mouse model of Parkinson’s disease (PD). An experimental model of PD was created by four intraperitoneal injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (4 × 20 mg/kg, at 12 h intervals). Docosahexaenoic acid was given daily by gavage for 4 weeks (36 mg/kg/day). The motor activity of the mice was evaluated via the pole test, and the dopaminergic lesion was determined by immunohistochemical analysis for tyrosine hydroxylase (TH)-immunopositive cells. The activity of antioxidant enzymes in the brain were determined by spectrophotometric assays and the concentration of thiobarbituric acid-reactive substances (TBARS) were measured as an index of oxidative damage. The number of apoptotic dopaminergic cells significantly increased in MPTP-treated mice compared to controls. Although DHA significantly diminished the number of cell deaths in MPTP-treated mice, it did not improve the decreased motor activity observed in the experimental PD model. Docosahexaenoic acid significantly diminished the amount of cell death in the MPTP + DHA group as compared to the MPTP group. TBARS levels in the brain were significantly increased following MPTP treatment. Glutathione peroxidase (GPx) and catalase (CAT) activities of brain were unaltered in all groups. The activity of brain superoxide dismutase (SOD) was decreased in the MPTP-treated group compared to the control group, but DHA treatment did not have an effect on SOD activity in the MPTP + DHA group. Our current data show that DHA treatment exerts neuroprotective actions on an experimental mouse model of PD. There was a decrease tendency in brain lipid oxidation of MPTP mice but it did not significantly. 相似文献
29.
30.
Electroencephalography (EEG) signals collected from human brains have generally been used to diagnose diseases. Moreover, EEG signals can be used in several areas such as emotion recognition, driving fatigue detection. This work presents a new emotion recognition model by using EEG signals. The primary aim of this model is to present a highly accurate emotion recognition framework by using both a hand-crafted feature generation and a deep classifier. The presented framework uses a multilevel fused feature generation network. This network has three primary phases, which are tunable Q-factor wavelet transform (TQWT), statistical feature generation, and nonlinear textural feature generation phases. TQWT is applied to the EEG data for decomposing signals into different sub-bands and create a multilevel feature generation network. In the nonlinear feature generation, an S-box of the LED block cipher is utilized to create a pattern, which is named as Led-Pattern. Moreover, statistical feature extraction is processed using the widely used statistical moments. The proposed LED pattern and statistical feature extraction functions are applied to 18 TQWT sub-bands and an original EEG signal. Therefore, the proposed hand-crafted learning model is named LEDPatNet19. To select the most informative features, ReliefF and iterative Chi2 (RFIChi2) feature selector is deployed. The proposed model has been developed on the two EEG emotion datasets, which are GAMEEMO and DREAMER datasets. Our proposed hand-crafted learning network achieved 94.58%, 92.86%, and 94.44% classification accuracies for arousal, dominance, and valance cases of the DREAMER dataset. Furthermore, the best classification accuracy of the proposed model for the GAMEEMO dataset is equal to 99.29%. These results clearly illustrate the success of the proposed LEDPatNet19. 相似文献