全文获取类型
收费全文 | 577篇 |
免费 | 20篇 |
国内免费 | 38篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 12篇 |
2014年 | 16篇 |
2013年 | 17篇 |
2012年 | 24篇 |
2011年 | 35篇 |
2010年 | 55篇 |
2009年 | 39篇 |
2008年 | 26篇 |
2007年 | 40篇 |
2006年 | 35篇 |
2005年 | 40篇 |
2004年 | 31篇 |
2003年 | 32篇 |
2002年 | 30篇 |
2001年 | 15篇 |
2000年 | 4篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1975年 | 3篇 |
1971年 | 4篇 |
1958年 | 6篇 |
1955年 | 1篇 |
1954年 | 2篇 |
1951年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有635条查询结果,搜索用时 31 毫秒
1.
JEONG-WEON KIM MIKE F. SLAVIK 《Journal of Rapid Methods and Automation in Microbiology》1996,4(3):183-190
Blue Lake, an insoluble dye, was evaluated as an indicator of potential bacterial penetration into eggs. Various groups of eggs (fresh-laid; commercial; water-washed) were dipped in 0.25% (w/v) Blue Lake in 0.1% Triton X-100 solution for 2 min and incubated at room temperature up to 1 ± 24 h. Penetration was detected by counting the blue dots on shell membranes after breaking the eggs. Commercial eggs allowed the easiest penetration. All commercial eggs showed blue dots even at 2 min incubation and the average count reached 111/egg at 1 h. Water-washed eggs allowed much less penetration than commercial eggs and the counts of blue dots on those eggs were 10/egg at 2 min and 22 at 1 h. Fresh-laid eggs did not allow any penetration up to 24 h. Above results corresponded very well with the penetration study with Salmonella enteritidis and also with the morphological study of eggshell surfaces using electron microscopy where fresh-laid eggs had intact cuticle layers, but commercial eggs did not. Thus, Blue Lake dye might be used as a rapid indicator of bacterial penetration through eggshells. 相似文献
2.
3.
In searching for differentially expressed genes in human uterine leiomyomas (ULs), suppression sub-tractive hybridization was used to construct an UL up-regulated library, which turned out to represent 88genes. After two rounds of screening by reverse Northern analysis, twenty genes were proved to be up-regulated, including seventeen known genes and three genes with unknown function. All these genes werefirstly associated with UL. Three genes with notable difference were selected for Northern confirmationOur results proved the authenticity of the twenty genes. One gene named Phospholipase A2 (PLA2) showedup-regulation in 4/6 of the patients and investigation of tissue distribution indicated that it had obviousexpression in prostate, testis, liver, heart and skeletal muscle. 相似文献
4.
The family Embolemidae Westwood, 1833 is recorded for the first time in Korea, based on a species Embolemus ruddii Westwood. A diagnosis of this species complemented by digital images are provided. 相似文献
5.
Robin F. MORALES Ki Moon SEONG Cha Soon KIM Young-Woo JIN Kyung-Jin MIN 《Entomological Research》2010,40(4):225-228
It is well known that music can have calming effects on humans, other mammals and birds. Reducing environmental stress or enhancing the resistance to certain stressors has been shown to extend lifespan in several organisms. Evidence also suggests that mild temporary stress may also enhance stress resistance and ultimately slow the aging process. This study explored the possibility that music may influence the lifespan of the fruit fly Drosophila melanogaster, possibly by affecting responses to stress. Flies received either background sounds (control), or background sounds supplemented with music (experimental). The experimental group had classical music playing constantly at an average of 20 dB above background sound. The median lifespan of females receiving music was 42 days compared to the median of 45 days without music, but the difference was not significant. For males median lifespans were 42 days with music exposure, and 47 days without music and the difference was significant. These results suggest that exposure to classical music decreased the lifespan of male Drosophila. Both experimental and control populations showed age-dependent increases in mortality, indicating that music affects the normal aging process rather than showing overt toxicity. These results suggest that certain auditory stimuli may be stressful and can be used as insect management. 相似文献
6.
7.
8.
9.
10.
Integrated species delimitation and conservation implications of an endangered weevil Pachyrhynchus sonani (Coleoptera: Curculionidae) in Green and Orchid Islands of Taiwan 下载免费PDF全文
YEN‐TING CHEN HUI‐YUN TSENG MING‐LUEN JENG YONG‐CHAO SU WEN‐SAN HUANG CHUNG‐PING LIN 《Systematic Entomology》2017,42(4):796-813
Oceanic islands are productive habitats for generating new species and high endemism, which is primarily due to their geographical isolation, smaller population sizes and local adaptation. However, the short divergence times and subtle morphological or ecological divergence of insular organisms may obscure species identity, so the cryptic endemism on islands may be underestimated. The endangered weevil Pachyrhynchus sonani Kôno (Coleoptera: Curculionidae: Entiminae: Pachyrhynchini) is endemic to Green Island and Orchid Island of the Taiwan‐Luzon Archipelago and displays widespread variation in coloration and host range, thus raising questions regarding its species boundaries and degree of cryptic diversity. We tested the species boundaries of P. sonani using an integrated approach that combined morphological (body size and shape, genital shape, coloration and cuticular scale), genetic (four genes and restriction site‐associated DNA sequencing, RAD‐seq) and ecological (host range and distribution) diversity. The results indicated that all the morphological datasets for male P. sonani, except for the colour spectrum, reveal overlapping but statistically significant differences between islands. In contrast, the morphology of the female P. sonani showed minimum divergence between island populations. The populations of P. sonani on the two islands were significantly different in their host ranges, and the genetic clustering and phylogenies of P. sonani established two valid evolutionary species. Integrated species delimitation combining morphological, molecular and ecological characters supported two distinct species of P. sonani from Green Island and Orchid Island. The Green Island population was described as P. jitanasaius sp.n. Chen & Lin, and it is recommended that its threatened conservation status be recognized. Our findings suggest that the inter‐island speciation of endemic organisms inhabiting both islands may be more common than previously thought, and they highlight the possibility that the cryptic diversity of small oceanic islands may still be largely underestimated. 相似文献