全文获取类型
收费全文 | 2390篇 |
免费 | 104篇 |
国内免费 | 106篇 |
出版年
2024年 | 10篇 |
2023年 | 145篇 |
2022年 | 357篇 |
2021年 | 545篇 |
2020年 | 227篇 |
2019年 | 77篇 |
2018年 | 50篇 |
2017年 | 30篇 |
2016年 | 33篇 |
2015年 | 26篇 |
2014年 | 68篇 |
2013年 | 103篇 |
2012年 | 46篇 |
2011年 | 68篇 |
2010年 | 44篇 |
2009年 | 65篇 |
2008年 | 59篇 |
2007年 | 85篇 |
2006年 | 52篇 |
2005年 | 57篇 |
2004年 | 48篇 |
2003年 | 59篇 |
2002年 | 36篇 |
2001年 | 28篇 |
2000年 | 14篇 |
1999年 | 29篇 |
1998年 | 24篇 |
1997年 | 18篇 |
1996年 | 6篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1975年 | 5篇 |
排序方式: 共有2600条查询结果,搜索用时 437 毫秒
91.
Farhan Haq Salmaan Sharif Adnan Khurshid Aamer Ikram Imran Shabbir Muhammad Salman Abdul Ahad Muhammad Suleman Rana Aroosha Raja Nazish Badar Hanaa Tashkandi Turki Al Amri Esam I. Azhar Mohammed S. Almuhayawi Steve Harakeh Muhammad Faraz Arshad Malik 《Saudi Journal of Biological Sciences》2021,28(1):942
92.
This paper estimates how previous major pandemic events affected economic and gender inequalities in the short- to medium run. We consider the impact of six major pandemic episodes – H3N2 Flu (1968), SARS (2003), H1N1 Swine Flu (2009), MERS (2012), Ebola (2014), and Zika (2016) – on cross-country inequalities in samples of 46–167 countries observed over 1950–2019. Results show that the past pandemics have moderately increased income inequality in the affected countries in the period of four to five years after the pandemic’s start. On the other hand, we do not find any robust negative impacts on wealth inequality. The results concerning gender inequality are less consistent, but we find some evidence of declining gender equality among the hardest hit countries. Moreover, the gender gap in unemployment grew within the four years after the onset of the pandemic. 相似文献
93.
In early 2020 the world was struck by the epidemic of novel SARS-CoV-2 virus. Like many others, German government has introduced severe contact restrictions to limit the spread of infection. This paper analyses effects of weather on the spread of the disease under the described circumstances. We demonstrate that regions reported lower growth rates of the number of the infection cases after days with higher temperatures, no rain and low humidity. We argue that this effect is channelled through human behaviour. The evidence suggests that “good” weather attracts individuals to outdoor (safer) environments, thus, deterring people from indoor (less safe) environments. Understanding this relationship is important for improving the measures aiming at combating the spread of the virus. 相似文献
94.
PurposeTo assess the impact of lung segmentation accuracy in an automatic pipeline for quantitative analysis of CT images.MethodsFour different platforms for automatic lung segmentation based on convolutional neural network (CNN), region-growing technique and atlas-based algorithm were considered. The platforms were tested using CT images of 55 COVID-19 patients with severe lung impairment. Four radiologists assessed the segmentations using a 5-point qualitative score (QS). For each CT series, a manually revised reference segmentation (RS) was obtained. Histogram-based quantitative metrics (QM) were calculated from CT histogram using lung segmentationsfrom all platforms and RS. Dice index (DI) and differences of QMs (ΔQMs) were calculated between RS and other segmentations.ResultsHighest QS and lower ΔQMs values were associated to the CNN algorithm. However, only 45% CNN segmentations were judged to need no or only minimal corrections, and in only 17 cases (31%), automatic segmentations provided RS without manual corrections. Median values of the DI for the four algorithms ranged from 0.993 to 0.904. Significant differences for all QMs calculated between automatic segmentations and RS were found both when data were pooled together and stratified according to QS, indicating a relationship between qualitative and quantitative measurements. The most unstable QM was the histogram 90th percentile, with median ΔQMs values ranging from 10HU and 158HU between different algorithms.ConclusionsNone of tested algorithms provided fully reliable segmentation. Segmentation accuracy impacts differently on different quantitative metrics, and each of them should be individually evaluated according to the purpose of subsequent analyses. 相似文献
95.
Nighat Perveen Sabir Bin Muzaffar Mohammad Ali Al-Deeb 《Saudi Journal of Biological Sciences》2021,28(2):1417-1425
The novel coronavirus disease (COVID-19) that emerged in December 2019 had caused substantial morbidity and mortality at the global level within few months. It affected economies, stopped travel, and isolated individuals and populations around the world. Wildlife, especially bats, serve as reservoirs of coronaviruses from which the variant Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) emerged that causes COVID-19. In this review, we describe the current knowledge on COVID-19 and the significance of wildlife hosts in its emergence. Mammalian and avian coronaviruses have diverse host ranges with distinct lineages of coronaviruses. Recombination and reassortments occur more frequently in mixed-animal markets where diverse viral genotypes intermingle. Human coronaviruses have evolved through gene gains and losses primarily in interfaces where wildlife and humans come in frequent contact. There is a gap in our understanding of bats as reservoirs of coronaviruses and there is a misconception that bats periodically transmit coronaviruses to humans. Future research should investigate bat viral diversity and loads at interfaces between humans and bats. Furthermore, there is an urgent need to evaluate viral strains circulating in mixed animal markets, where the coronaviruses circulated before becoming adapted to humans. We propose and discuss a management intervention plan for COVID-19 and raise questions on the suitability of current containment plans. We anticipate that more virulent coronaviruses could emerge unless proper measures are taken to limit interactions between diverse wildlife and humans in wild animal markets. 相似文献
96.
Abdulaziz Almudhi 《Saudi Journal of Biological Sciences》2021,28(5):3110-3116
The Covid-19 pandemic is an ongoing crisis and is colloquially known as the corona virus pandemic. As no specific treatment protocol are available for this viral infection, social distancing is considered as one of the remedies to prevent the infection. This study aimed to investigate the anxiety issues in persons who stutter (PWS). A total of 110 (55 PWS and 55 Neuro-typical Adults) were enrolled for the study. A questionnaire comprising of two parts on social anxiety and consequences of social distancing was administered on the participants. The results showed that PWS felt more socially anxious. PWS opined that they were comfortable during the corona virus lockdown period, as the situation demanded them to speak minimally to strangers. Neuro-typical adults, on the other hand, reported that they did not observe any change with respect to the social communication skills during lockdown. 相似文献
97.
The outbreak of the coronavirus disease 2019 (COVID-19) continues to constitute an international public health emergency. Seasonality is a long-recognized attribute of many viral infections of humans. Nevertheless, the relationship between environmental factors and the spread of infection, particularly for person-to-person communicable diseases, remains poorly understood. This study explores the relationship between environmental factors and the incidence of COVID-19 in 188 countries with reported COVID-19 cases as of April 13, 2020. Here we show that COVID-19 growth rates peaked in temperate zones in the Northern Hemisphere during the outbreak period, while they were lower in tropical zones. The relationships between COVID-19 and environmental factors were resistant to the potentially confounding effects of air pollution, sea level, and population. To prove the effect of those factors, study, and analysis of the prevalence of COVID-19 in Italy, Spain, and China was undertaken. A fuzzy logic system was designed to predict the effects of that variables on the rate of viral spread of COVID-19. 相似文献
98.
99.
100.
《Autophagy》2013,9(2):278-280
Mitochondria autophagy (mitophagy) is the process of selective degradation of mitochondria that has an important role in mitochondrial quality control. To gain insight into the molecular mechanism of mitophagy, we screened a yeast knockout library for strains that are defective in mitophagy. We found 32 strains that showed a complete or partial block of mitophagy. One of the genes identified, YLR356W, is required for mitophagy, but not for macroautophagy or other types of selective autophagy. The deletion of YLR356W partially inhibits mitophagy during starvation, whereas there is almost complete inhibition at post-log phase. Accordingly, we hypothesize that Ylr356w is required to detect or present aged or dysfunctional mitochondria when cells reach the post-log phase. 相似文献