全文获取类型
收费全文 | 78篇 |
免费 | 0篇 |
专业分类
系统科学 | 1篇 |
现状及发展 | 36篇 |
研究方法 | 1篇 |
综合类 | 37篇 |
自然研究 | 3篇 |
出版年
2015年 | 1篇 |
2013年 | 1篇 |
2011年 | 5篇 |
2008年 | 3篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2003年 | 1篇 |
2002年 | 1篇 |
1996年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 4篇 |
1967年 | 7篇 |
1966年 | 3篇 |
1965年 | 6篇 |
1964年 | 2篇 |
1958年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有78条查询结果,搜索用时 15 毫秒
21.
Stress changes from the 2008 Wenchuan earthquake and increased hazard in the Sichuan basin 总被引:39,自引:0,他引:39
On 12 May 2008, the devastating magnitude 7.9 (Wenchuan) earthquake struck the eastern edge of the Tibetan plateau, collapsing buildings and killing thousands in major cities aligned along the western Sichuan basin in China. After such a large-magnitude earthquake, rearrangement of stresses in the crust commonly leads to subsequent damaging earthquakes. The mainshock of the 12 May earthquake ruptured with as much as 9 m of slip along the boundary between the Longmen Shan and Sichuan basin, and demonstrated the complex strike-slip and thrust motion that characterizes the region. The Sichuan basin and surroundings are also crossed by other active strike-slip and thrust faults. Here we present calculations of the coseismic stress changes that resulted from the 12 May event using models of those faults, and show that many indicate significant stress increases. Rapid mapping of such stress changes can help to locate fault sections with relatively higher odds of producing large aftershocks. 相似文献
22.
Fundamental misunderstandings about classification can lead scientists down unproductive or dangerous paths, argue Jeffrey Parsons and Yair Wand. 相似文献
23.
The charaeteristics of kokanee ( Oncorhynchus nerka ) spawning stocks in the Green River and Sheep Creek (tributaries to Flaming Gorge Reservoir) are described as observed in fall 1985 and spring 1986; the time of spawning; length, age, and sex structure of the stocks; fecundity and egg retention; density of eggs in redds; and the timing of downstream drift of emerging fry. The time of spawning, length-frequency distributions of spawning fish, and egg density in redds differed between the two stocks, but other differences were not observed. 相似文献
24.
At the frog neuromuscular junction tetraphenylboron produced a decrease in miniature endplate potential amplitude, accompanied by a decrease in the number but not the size of synaptic vesicles. 相似文献
25.
26.
One species of copepod ( Ergasilus elongatus ), one trematode ( Diclybothrium hamulatum ), two nematodes ( Camallanus oxycephalus and Contracaecum sp.), and two cestodes ( Marsipometra hastata and M. parva ) were recovered from 17 paddlefish ( Polyodon spathula ) collected from the Yellowstone River, Montana, on 11 and 18 May 1973. The male paddlefish averaged 69.4 nematodes and 157.6 cestodes per infected fish while the females averaged 12.0 nematodes and 415.7 cestodes. The higher intensity of cestode infection in female paddlefish was attributed to their larger size and consequent greater intake of food resulting in more exposure to the cestode intermediate hosts ( Cyclops bicuspidatus ). 相似文献
27.
Saal LH Gruvberger-Saal SK Persson C Lövgren K Jumppanen M Staaf J Jönsson G Pires MM Maurer M Holm K Koujak S Subramaniyam S Vallon-Christersson J Olsson H Su T Memeo L Ludwig T Ethier SP Krogh M Szabolcs M Murty VV Isola J Hibshoosh H Parsons R Borg A 《Nature genetics》2008,40(1):102-107
Basal-like breast cancer (BBC) is a subtype of breast cancer with poor prognosis. Inherited mutations of BRCA1, a cancer susceptibility gene involved in double-strand DNA break (DSB) repair, lead to breast cancers that are nearly always of the BBC subtype; however, the precise molecular lesions and oncogenic consequences of BRCA1 dysfunction are poorly understood. Here we show that heterozygous inactivation of the tumor suppressor gene Pten leads to the formation of basal-like mammary tumors in mice, and that loss of PTEN expression is significantly associated with the BBC subtype in human sporadic and BRCA1-associated hereditary breast cancers. In addition, we identify frequent gross PTEN mutations, involving intragenic chromosome breaks, inversions, deletions and micro copy number aberrations, specifically in BRCA1-deficient tumors. These data provide an example of a specific and recurrent oncogenic consequence of BRCA1-dependent dysfunction in DNA repair and provide insight into the pathogenesis of BBC with therapeutic implications. These findings also argue that obtaining an accurate census of genes mutated in cancer will require a systematic examination for gross gene rearrangements, particularly in tumors with deficient DSB repair. 相似文献
28.
Responses ofDrosophila to environmental ethanol from ecologically optimal and extreme habitats 总被引:1,自引:0,他引:1
P. A. Parsons 《Cellular and molecular life sciences : CMLS》1980,36(9):1070-1071
Summary Adult tolerances and larval behaviour in the presence of ethanol is more variable in populations derived from optimal habitats than those from extreme habitats. Since the habitat types are defined ecologically in terms of climatic and biotic factors, this result has biological significance for defining the properties of populations from extreme habitats.I thank Garry Spence for technical assistance, and the Australian Research Grants Committee for partial financial support. 相似文献
29.
P. A. Parsons 《Cellular and molecular life sciences : CMLS》1964,20(10):569-570
Résumé Chez quelques lignées pures et hybrides deDrosophila melanogaster l'accouplement sexuel s'effectue avec des vitesses variables. On peut conclure que la constitution génotypique exerce une action très importante sur la vitesse de l'accouplement. 相似文献
30.