全文获取类型
收费全文 | 246篇 |
免费 | 26篇 |
专业分类
272篇 |
出版年
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 12篇 |
2019年 | 10篇 |
2018年 | 16篇 |
2017年 | 6篇 |
2016年 | 14篇 |
2015年 | 15篇 |
2014年 | 17篇 |
2013年 | 19篇 |
2012年 | 8篇 |
2011年 | 3篇 |
2010年 | 5篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 11篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有272条查询结果,搜索用时 15 毫秒
261.
Jamal Rahmani Alberto Montesanto Edward Giovannucci Hamid Zand Meisam Barati John J. Kopchick Mario G. Mirisola Vincenzo Lagani Hiba Bawadi Raffaele Vardavas Alessandro Laviano Kaare Christensen Giuseppe Passarino Valter D. Longo 《Aging cell》2022,21(2)
The association between IGF‐1 levels and mortality in humans is complex with low levels being associated with both low and high mortality. The present meta‐analysis investigates this complex relationship between IGF‐1 and all‐cause mortality in prospective cohort studies. A systematic literature search was conducted in PubMed/MEDLINE, Scopus, and Cochrane Library up to September 2019. Published studies were eligible for the meta‐analysis if they had a prospective cohort design, a hazard ratio (HR) and 95% confidence interval (CI) for two or more categories of IGF‐1 and were conducted among adults. A random‐effects model with a restricted maximum likelihood heterogeneity variance estimator was used to find combined HRs for all‐cause mortality. Nineteen studies involving 30,876 participants were included. Meta‐analysis of the 19 eligible studies showed that with respect to the low IGF‐1 category, higher IGF‐1 was not associated with increased risk of all‐cause mortality (HR = 0.84, 95% CI = 0.68–1.05). Dose–response analysis revealed a U‐shaped relation between IGF‐1 and mortality HR. Pooled results comparing low vs. middle IGF‐1 showed a significant increase of all‐cause mortality (HR = 1.33, 95% CI = 1.14–1.57), as well as comparing high vs. middle IGF‐1 categories (HR = 1.23, 95% CI = 1.06–1.44). Finally, we provide data on the association between IGF‐1 levels and the intake of proteins, carbohydrates, certain vitamins/minerals, and specific foods. Both high and low levels of IGF‐1 increase mortality risk, with a specific 120–160 ng/ml range being associated with the lowest mortality. These findings can explain the apparent controversy related to the association between IGF‐1 levels and mortality. 相似文献
262.
Gorzi Ali Rahmani Ahmad Mohammadi Zahra Neto Walter Krause 《Molecular biology reports》2021,48(6):5003-5011
Molecular Biology Reports - There is a lack of evidence on the effects of high-intensity interval training (HIIT) microcycle duration on the antioxidant capacity and hippocampal inflammatory... 相似文献
263.
264.
Platform carbonate sediments of Oligocene–Miocene age (Asmari Formation) in the Zagros Basin (SW Iran) have been investigated in order to determine their paleoecology and depositional environment. The Zagros Basin is the result of the opening and closure of the Neo-Tethys Ocean along the northeastern border of the Arabian Plate. The thick sedimentary sequences of the Zagros Basin contain rocks ranging in age from Cambrian to recent. The geological evidence suggests that the region was part of a passive continental margin, which subsequently underwent rifting in the Permo-Trias and collision in the Late Tertiary. The Asmari carbonate system was dominated by foraminifera and corallinacean assemblage. Based on the distribution of the larger foraminifera, four assemblage zones have been recognised. Facies analysis allowed the recognition of nine microfacies types that are grouped into three depositional environments that correspond to the inner, middle and outer shelf. The biota assemblage of the Asmari Formation suggests that carbonate sedimentation took place in tropical waters and oligotrophic to slightly mesotrophic conditions. Our detailed analysis of microfacies and paleoecology shows that the Asmari Formation deposited on a carbonate open shelf dominated by heterozoan and, subordinately, photozoan skeletal assemblage. 相似文献
265.
In recent years, extensive studies have been conducted on the diagnosis of Alzheimer''s disease (AD) using the non-invasive speech signal recognition method. In this study, Farsi speech signals were analyzed using the auditory model system (AMS) in order to recognize AD. For this purpose, after the pre-processing of the speech signals and utilizing AMS, 4D outputs as function of time, frequency, rate, and scale range were obtained. The AMS outcomes were averaged in term of time to analyze the rate-frequency-scale for both groups, Alzheimer''s and healthy control subjects. Thereafter, the maximum of spectral and temporal modulation and frequency were extracted to classify by the support vector machine (SVM). The SVM achieves higher promising recognition accuracy with compare to prevalent approaches in the field of speech processing. The acceptable results demonstrate the applicability of the proposed algorithm in non-invasive and low-cost recognizing Alzheimer''s only using the few extracted features of the speech signal. 相似文献
266.
Shahin Amiri Setare Adibzadeh Samaneh Ghanbari Behnaz Rahmani Mohammad H. Kheirandish Aref Farokhi-Fard Mansoureh S. Dastjerdeh Fatemeh Davami 《Biotechnology and bioengineering》2023,120(4):865-902
For industrial production of recombinant protein biopharmaceuticals, Chinese hamster ovary (CHO) cells represent the most widely adopted host cell system, owing to their capacity to produce high-quality biologics with human-like posttranslational modifications. As opposed to random integration, targeted genome editing in genomic safe harbor sites has offered CHO cell line engineering a new perspective, ensuring production consistency in long-term culture and high biotherapeutic expression levels. Corresponding the remarkable advancements in knowledge of CRISPR-Cas systems, the use of CRISPR-Cas technology along with the donor design strategies has been pushed into increasing novel scenarios in cell line engineering, allowing scientists to modify mammalian genomes such as CHO cell line quickly, readily, and efficiently. Depending on the strategies and production requirements, the gene of interest can also be incorporated at single or multiple loci. This review will give a gist of all the most fundamental recent advancements in CHO cell line development, such as different cell line engineering approaches along with donor design strategies for targeted integration of the desired construct into genomic hot spots, which could ultimately lead to the fast-track product development process with consistent, improved product yield and quality. 相似文献
267.
Forests are vital for biodiversity, carbon storage and ecosystem services, but can be potentially threatened by fires. Given the significance of forests and fire in a changing climate, research into the long-term effects of fire on forests plays an important role in understanding the global carbon cycle by the forests functioning as a large terrestrial carbon sink or source. In this study, we used aerial photography from 1975 and 2013 to count the change in the number of trees in 560 dry sclerophyll plots (40 × 40m) in the Blue Mountains of Australia. We analysed the relationship between the number of fires and severe fires in that period on the change in numbers of trees. We found that the average response was an increase of 1 tree per plot over 38 years. The number of fires had a small positive effect on tree numbers; plots with 2 or 3 severe fires had 1 and 2 extra trees, respectively, than those without fire. One exception was a severe fire in 2001 that did not show this positive effect, probably because it corresponded with extensive drought. Our findings suggest that number of forest canopy trees is resilient to the number of fires and number of severe fires. 相似文献
268.
Houshang Nemati Reza Khodarahmi Ameneh Rahmani Ali Ebrahimi Mojtaba Amani Kamran Eftekhari 《Cell biochemistry and function》2013,31(1):36-40
Psoriasis is a chronic inflammatory skin disease characterized by excessive cellular replication. Apolipoproteins are genetically determined molecule whose role has been implied in cardiovascular pathology. Vascular adhesion protein?1 (VAP?1) is an adhesion molecule with an enzymatic activity that partakes in the migration process of lymphocytes into sites of inflammation. Our purpose was to evaluate the plasma lipid profiles, apolipoproteins (A1, B) and Lp (a) and VAP?1 in order to compare the lipid profile in psoriatic patients with non‐affected persons and correlation between VAP?1 and Lp (a). We determined serum concentrations of lipids, lipoproteins , apolipoproteins and VAP?1 in 90 patients with psoriasis and 90 age matched controls. Serum Lp (a), apo A1 and apo B were measured by immunoprecipitation assays, and the lipids and lipoproteins were measured by enzymatic methods.The VAP?1 were masured by ELISA method. The mean levels of total cholesterol, LDL, apo B and VAP?1 in patients with psoriasis were found to be significantly higher than those of healthy subjects (P<0.05. In psoriatic patients, elevation of VAP‐1 correlated with elevation of Lp (a) (p = 0.025). This study shows that high serum lipid level and VAP?1, is significantly more common in psoriasis. This fact may be responsible for higher prevalence of cardiovascular accident in psoriatic patients. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
269.
This study examined the ability of duckweed (Lemna minor) to remove soluble lead from water. The duckweed was obtained from the Devils Lake wastewater treatment plant in North Dakota. The viable aquatic plants were exposed to a single dose of lead (from Pb(NO3)2) at a concentration of 5.0 mg/l for a time period of 21 days. Lead concentrations were measured in the water daily and in the biomass at the conclusion of the experiment. All measurements were done in triplicate and performed in accordance with standard methods. These data were used to calculate the removal efficiency with respect to time, and to provide the necessary empirical constants to model the removal behavior. Viable biomass removed 85–90% of the lead, viable duckweed previously exposed to lead removed 70–80% of the lead, non-viable biomass (control group) removed 60–75% of the lead, and there was no removal in the ‘no-biomass' control group. Based on these results we conclude that the viable biomass is effective in removing lead present at sub-lethal levels. 相似文献
270.