全文获取类型
收费全文 | 207篇 |
免费 | 25篇 |
国内免费 | 28篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 9篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 24篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 11篇 |
2008年 | 14篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有260条查询结果,搜索用时 15 毫秒
251.
Steven J. Portugal Craig R. White Peter B. Frappell Jonathan A. Green Patrick J. Butler 《Ecology and evolution》2019,9(14):7974-7984
The position of the Moon in relation to the Earth and the Sun gives rise to several predictable cycles, and natural changes in nighttime light intensity are known to cause alterations to physiological processes and behaviors in many animals. The limited research undertaken to date on the physiological responses of animals to the lunar illumination has exclusively focused on the synodic lunar cycle (full moon to full moon, or moon phase) but the moon's orbit—its distance from the Earth—may also be relevant. Every month, the moon moves from apogee, its most distant point from Earth—and then to perigee, its closest point to Earth. Here, we studied wild barnacle geese (Branta leucopsis) to investigate the influence of multiple interacting lunar cycles on the physiology of diurnally active animals. Our study, which uses biologging technology to continually monitor body temperature and heart rate for an entire annual cycle, asks whether there is evidence for a physiological response to natural cycles in lunar brightness in wild birds, particularly “supermoon” phenomena, where perigee coincides with a full moon. There was a three‐way interaction between lunar phase, lunar distance, and cloud cover as predictors of nighttime mean body temperature, such that body temperature was highest on clear nights when the full moon coincided with perigee moon. Our study is the first to report the physiological responses of wild birds to “supermoon” events; the wild geese responded to the combination of two independent lunar cycles, by significantly increasing their body temperature at night. That wild birds respond to natural fluctuations in nighttime ambient light levels support the documented responses of many species to anthropogenic sources of artificial light, that birds seem unable to override. As most biological systems are arguably organized foremost by light, this suggests that any interactions between lunar cycles and local weather conditions could have significant impacts on the energy budgets of birds. 相似文献
252.
Jiaxiong Luo Haishu Tan Ruofei Wu Sicong Zhu Hanbao Chen Junrui Zhen Jiancong Li Caizhong Guan Yanxiong Wu 《Journal of biophotonics》2023,16(3):e202200240
Fourier ptychographic microscopy (FPM) is a promising super-resolution computational imaging technology. It stitches a series of low-resolution (LR) images in the Fourier domain by an iterative method. Thus, it obtains a large field of view and high-resolution quantitative phase images. Owing to its capability to perform high-spatial bandwidth product imaging, FPM is widely used in the reconstruction of conventional static samples. However, the influence of the FPM imaging mechanism limits its application in high-speed dynamic imaging. To solve this problem, an adaptive-illumination FPM scheme using regional energy estimation is proposed. Starting with several captured real LR images, the energy distribution of all LR images is estimated, and select the measurement images with large information to perform FPM reconstruction. Simulation and experimental results show that the method produces efficient imaging performance and reduces the required volume of data to more than 65% while ensuring the quality of FPM reconstruction. 相似文献
253.
Vibor Laketa 《Journal of molecular biology》2018,430(17):2612-2625
A comprehensive understanding of host–pathogen interactions requires quantitative assessment of molecular events across a wide range of spatiotemporal scales and organizational complexities. Due to recent technical developments, this is currently only achievable with microscopy. This article is providing a general perspective on the importance of microscopy in infectious disease research, with a focus on new imaging modalities that promise to have a major impact in biomedical research in the years to come. Every major technological breakthrough in light microscopy depends on, and is supported by, advancements in computing and information technologies. Bioimage acquisition and analysis based on machine learning will pave the way toward more robust, automated and objective implementation of new imaging modalities and in biomedical research in general. The combination of novel imaging technologies with machine learning and near-physiological model systems promises to accelerate discoveries and breakthroughs in our understanding of infectious diseases, from basic research all the way to clinical applications. 相似文献
254.
Cerium oxide nanoparticles have been shown to sensitize cancer cells to radiation damage. Their unique redox properties confer excellent therapeutic potential by augmenting radiation dose with reactive oxygen species mediating bystander effects. Owing to its metallic properties, cerium oxide nanoparticles can be visualized inside cells using reflected light and optical sectioning. This can be advantageous in settings requiring none or minimal sample preparation and modification. We investigated the use of reflectance imaging for the detection of unmodified nanoceria in MDA MB231 breast cancer cells along with differential interference contrast imaging and fluorescent nuclear labeling. We also performed studies to evaluate the uptake capability, cellular toxicity and redox properties of nanocaria in these cells. Our results demonstrate that reflectance structured illumination imaging can effectively localize cerium oxide nanoparticles in breast cancer cells, and when combining with differential interference contrast and fluorescent cell label imaging, effective compartmental localization of the nanoparticles can be achieved. The total number of cells taking up the nanoparticles and the amount of nanoparticle uptake increased significantly in proportion to the dose, with no adverse effects on cell survival. Moreover, significant reduction in reactive oxygen species was also observed in proportion to increasing nanoceria concentrations attesting to its ability to modulate oxidative stress. In conclusion, this work serves as a pre-clinical scientific evaluation of the effective use of reflectance structured illumination imaging of cerium oxide nanoparticles in breast cancer cells and the safe use of these nanoparticles in MDA MB231 cells for further therapeutic applications. 相似文献
255.
Zengxin Huang Panchun Gu Dengfeng Kuang Ping Mi Xizeng Feng 《Journal of biophotonics》2021,14(5):e202000466
Light sheet fluorescence microscopy has become a research hotspot in biomedicine because of low phototoxicity, high speed, and high resolution. However, the conventional methods to acquire three-dimensional spatial information are mainly based on scanning, which inevitably increases photodamage and is not real-time. Here, we propose a method to generate controllable multi-planar illumination with a dielectric isosceles triangular array and a design of multi-planar light sheet fluorescence microscopy system. We carry out experiments of three-dimensional illumination beam measurement, volumetric imaging of fluorescent microspheres, and dynamic in vivo imaging of zebrafish heart to evaluate the performance of this system. In addition, we apply this system to study the effects of bisphenol fluorene on the heart shape and heart-beating rate of zebrafish. Our experiment results indicate that the multi-planar light sheet microscopy system provides a novel and feasible method for three-dimensional selected plane imaging and low-phototoxicity in vivo imaging. 相似文献
256.
Jori O. Ruuskanen Jussi O. T. Sipilä Päivi Rautava Ville Kytö 《Chronobiology international》2018,35(8):1168-1174
Stroke occurrence shows strong correlations with sleep disorders and even subtle sleep disturbances have been shown to affect ischemic stroke (IS) occurrence. Chronobiology also exerts effects, like the morning surge in IS occurrence. Lunar cycles have also been shown to affect sleep and other physiological processes, but studies on moon phases and its possible association with occurrence of stroke are rare and nonconclusive. Therefore, we studied the effects of moon phases on stroke hospitalizations and in-hospital mortality nationwide in Finland in 2004–2014. All patients aged ≥18 years with IS or intracerebral hemorrhage (ICH) as primary discharge diagnosis were included. Daily number of admissions was treated as a response variable while moon phase, year and astronomical season were independent variables in Poisson regression modeling. We found no association between moon phases and stroke occurrence. The overall occurrence rates did not vary between different moon phases for IS or ICH (p = 0.61 or higher). There were no differences between moon phases in daily admission rates among men, women, young and old patients for any of the stroke subtypes. There was no difference in in-hospital mortality with regard to moon phase for IS or ICH overall (p = 0.19 or higher), nor in subgroup analyses. There were no significant interactions between moon phase and astronomical season for stroke occurrence or in-hospital mortality. To conclude, in this over a decade-long nationwide study including a total of 46 million person years of follow-up, we found no association between moon phases and occurrence or in-hospital mortality rates of IS or intracerebral hemorrhage. 相似文献
257.
Observational studies describe rough-toothed dolphins (Steno bredanensis) actively foraging during the day on epipelagic species. Using data from depth-transmitting satellite tags deployed on nine individuals off Kauaʻi, we investigated diving behavior and the effects of lunar phase and solar light levels on vertical movements. Overall, tagged rough-toothed dolphins primarily used near-surface waters, spending between 83.6% and 93.7% of their time in the top 30 m of the water column. When diving, grand mean, median, and maximum dive depths were 76.9 m, 67.5 m, and 399.5 m, although individuals were in water with depths from approximately 700–1,450 m. Dive rates varied by time of day, being lowest during the day and at dawn and highest at dusk and night. Dives were deepest (M = 133.7 m, SD = 52.6 m, median = 106.5 m) and longest (M = 4.0 min, SD = 0.4 min, median = 4.0 min) at dusk, suggesting dolphins were taking advantage of prey rising to the surface in response to reduced light levels. Lunar phase indirectly affected diving, with deeper and longer dives occurring with increasing illumination. The variations in dive behavior across solar and lunar cycles indicate diving patterns shift based on the distribution of prey. 相似文献
258.
Sumathy Babitha Julio C. Carvahlo Carlos R. Soccol Ashok Pandey 《World journal of microbiology & biotechnology》2008,24(11):2671-2675
The capacity to sense and respond to light is widespread in animals, plants, fungi and bacteria. The effect of light quality
on growth and pigment yield of Monascus purpureus was investigated. Incubation in total darkness increased red pigment production from 14. 5 OD/g dry substrate to 22 OD/g
dry substrate. In contrast, growth of the fungus in direct illumination resulted in total suppression of pigment production.
It was found that both red and blue light influenced pigment yield as well as culture morphology. The authors propose the
existence of a light-perception system in Monascus purpureus. 相似文献
259.
Lunar synchronization of spawning in cichlid fishes of the tribe Lamprologini in Lake Tanganyika 总被引:1,自引:0,他引:1
K. Nakai Y. Yanagisawa †† T. Sato Y. Niimura ‡ M. M. Gashagaza § 《Journal of fish biology》1990,37(4):589-598
Lunar synchronization of spawning was investigated for eight substrate brooding cichlid fishes belonging to the tribe Lamprologini. Their spawning activities all peaked during the second quarter of the lunar cycle. Comparison between their breeding styles and the degrees of spawning synchronization suggested that the nocturnal guarding-efficiency of eggs, especially exposed ones, is improved by the maximal amount of moonlight during full moon and, in species whose young leave the breeding sites about 2 weeks after spawning, the survival of dispersing young is enhanced by the darkness of moonless nights. 相似文献
260.
Abstract Permanent oestrus was induced in 24, 61 and 100% of 2‐months old Wistar rats under conditions of continuous light exposure (LL) for 1, 2 and 6 months, respectively. After cessation of 2 months LL, rhythmic fluctuations of oestrus activity were observed. The weight of newborns produced by females under LL during pregnancy was increased by 7% as compared to controls (P < 0.05). LL before mating did not affect embryonic development. 20‐day old pups produced by females which were kept in LL for 1, 2 months and more were significantly heavier than controls by 5, 18 and 30%, respectively. The stimulatory effect of LL for 1 and 2 months on pre‐ and postnatal development was maintained in the subsequent reproduction cycle, when these females were transferred to normal conditions of LD 14:10. 相似文献