全文获取类型
收费全文 | 5033篇 |
免费 | 563篇 |
国内免费 | 1篇 |
出版年
2022年 | 41篇 |
2021年 | 74篇 |
2020年 | 48篇 |
2019年 | 48篇 |
2018年 | 61篇 |
2017年 | 68篇 |
2016年 | 112篇 |
2015年 | 172篇 |
2014年 | 177篇 |
2013年 | 269篇 |
2012年 | 280篇 |
2011年 | 320篇 |
2010年 | 205篇 |
2009年 | 175篇 |
2008年 | 241篇 |
2007年 | 231篇 |
2006年 | 212篇 |
2005年 | 196篇 |
2004年 | 195篇 |
2003年 | 184篇 |
2002年 | 201篇 |
2001年 | 116篇 |
2000年 | 104篇 |
1999年 | 114篇 |
1998年 | 59篇 |
1997年 | 49篇 |
1996年 | 68篇 |
1995年 | 54篇 |
1994年 | 57篇 |
1993年 | 61篇 |
1992年 | 66篇 |
1991年 | 53篇 |
1990年 | 70篇 |
1989年 | 87篇 |
1988年 | 56篇 |
1987年 | 41篇 |
1986年 | 46篇 |
1985年 | 49篇 |
1984年 | 50篇 |
1983年 | 40篇 |
1982年 | 50篇 |
1981年 | 41篇 |
1980年 | 37篇 |
1979年 | 49篇 |
1978年 | 33篇 |
1977年 | 35篇 |
1976年 | 49篇 |
1975年 | 33篇 |
1974年 | 52篇 |
1973年 | 42篇 |
排序方式: 共有5597条查询结果,搜索用时 15 毫秒
991.
992.
A. J. Grant R. J. O'Connell 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2000,186(6):535-542
We recorded the electrophysiological responses of individual olfactory receptor neurons in sensilla trichodea on the antennae of adult arctiid moths, Utetheisa ornatrix, to stimulation with volatiles associated with both sexes. All trichoid sensilla contain at least two receptor neurons, each
with distinct action potential amplitudes and waveforms, that respond dichotomously to male and female odors. Although, neither
female neuron responds to extracts of coremata or the male-produced pheromone hydroxydanaidal, they do respond in a gender-specific
manner to the volatiles emanating from whole pupae, hemolymph, thoracic froth, and adult animals of several ages. Thoracic
froth, which contains pyrrolizidine alkaloids, is thought to play a role in defense. Froth from moths reared on diets, with
or without added pyrrolizidine alkaloids, were equally effective in eliciting gender-specific patterns of response. Male trichoid
receptor neurons respond to these same materials with similar patterns of activation. These receptor neurons provide information
about substances, which we have termed “gender odors,” that are persistently emitted by nearby animals. These substances do
not appear to be the same as those already known to be involved in defense or the sexual dialog between individuals.
Accepted: 16 March 2000 相似文献
993.
994.
995.
996.
Association between the gene encoding 5-lipoxygenase-activating protein and stroke replicated in a Scottish population 总被引:6,自引:0,他引:6
下载免费PDF全文
![点击此处可从《American journal of human genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Helgadottir A Gretarsdottir S St Clair D Manolescu A Cheung J Thorleifsson G Pasdar A Grant SF Whalley LJ Hakonarson H Thorsteinsdottir U Kong A Gulcher J Stefansson K MacLeod MJ 《American journal of human genetics》2005,76(3):505-509
Cardiovascular diseases, including myocardial infarction (MI) and stroke, most often occur on the background of atherosclerosis, a condition attributed to the interactions between multiple genetic and environmental risk factors. We recently reported a linkage and association study of MI and stroke that yielded a genetic variant, HapA, in the gene encoding 5-lipoxygenase-activating protein (ALOX5AP), that associates with both diseases in Iceland. We also described another ALOX5AP variant, HapB, that associates with MI in England. To further assess the contribution of the ALOX5AP variants to cardiovascular diseases in a population outside Iceland, we genotyped seven single-nucleotide polymorphisms that define both HapA and HapB from 450 patients with ischemic stroke and 710 controls from Aberdeenshire, Scotland. The Icelandic at-risk haplotype, HapA, had significantly greater frequency in Scottish patients than in controls. The carrier frequency in patients and controls was 33.4% and 26.4%, respectively, which resulted in a relative risk of 1.36, under the assumption of a multiplicative model (P=.007). We did not detect association between HapB and ischemic stroke in the Scottish cohort. However, we observed that HapB was overrepresented in male patients. This replication of haplotype association with stroke in a population outside Iceland further supports a role for ALOX5AP in cardiovascular diseases. 相似文献
997.
Grant CM Luikenhuis S Beckhouse A Soderbergh M Dawes IW 《Biochimica et biophysica acta》2000,1490(1-2):33-42
Glutaredoxins are small heat-stable proteins that are active as glutathione-dependent oxidoreductases and are encoded by two genes, designated GRX1 and GRX2, in the yeast Saccharomyces cerevisiae. We report here that the expression of both genes is induced in response to various stress conditions including oxidative, osmotic, and heat stress and in response to stationary phase growth and growth on non-fermentable carbon sources. Furthermore, both genes are activated by the high-osmolarity glycerol pathway and negatively regulated by the Ras-protein kinase A pathway via stress-responsive STRE elements. GRX1 contains a single STRE element and is induced to significantly higher levels compared to GRX2 following heat and osmotic shock. GRX2 contains two STRE elements, and is rapidly induced in response to reactive oxygen species and upon entry into stationary phase growth. Thus, these data support the idea that the two glutaredoxin isoforms in yeast play distinct roles during normal cellular growth and in response to stress conditions. 相似文献
998.
Peter R. Grant B. Rosemary Grant 《Evolution; international journal of organic evolution》1995,49(2):241-251
Microevolution of quantitative traits in the wild can be predicted from a knowledge of selection and genetic parameters. Testing the predictions requires measurement of the offspring of the selected group, a requirement that is difficult to meet. We present the results of a study of Darwin's finches on the Galápagos island of Daphne Major where this requirement is met. The study demonstrates microevolutionary consequences of natural selection. 相似文献
999.
Local and global pyrogeographic evidence that indigenous fire management creates pyrodiversity
下载免费PDF全文
![点击此处可从《Ecology and evolution》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Clay Trauernicht Barry W. Brook Brett P. Murphy Grant J. Williamson David M. J. S. Bowman 《Ecology and evolution》2015,5(9):1908-1918
Despite the challenges wildland fire poses to contemporary resource management, many fire‐prone ecosystems have adapted over centuries to millennia to intentional landscape burning by people to maintain resources. We combine fieldwork, modeling, and a literature survey to examine the extent and mechanism by which anthropogenic burning alters the spatial grain of habitat mosaics in fire‐prone ecosystems. We survey the distribution of Callitris intratropica, a conifer requiring long fire‐free intervals for establishment, as an indicator of long‐unburned habitat availability under Aboriginal burning in the savannas of Arnhem Land. We then use cellular automata to simulate the effects of burning identical proportions of the landscape under different fire sizes on the emergent patterns of habitat heterogeneity. Finally, we examine the global extent of intentional burning and diversity of objectives using the scientific literature. The current distribution of Callitris across multiple field sites suggested long‐unburnt patches are common and occur at fine scales (<0.5 ha), while modeling revealed smaller, patchy disturbances maximize patch age diversity, creating a favorable habitat matrix for Callitris. The literature search provided evidence for intentional landscape burning across multiple ecosystems on six continents, with the number of identified objectives ranging from two to thirteen per study. The fieldwork and modeling results imply that the occurrence of long‐unburnt habitat in fire‐prone ecosystems may be an emergent property of patch scaling under fire regimes dominated by smaller fires. These findings provide a model for understanding how anthropogenic burning alters spatial and temporal aspects of habitat heterogeneity, which, as the literature survey strongly suggests, warrant consideration across a diversity of geographies and cultures. Our results clarify how traditional fire management shapes fire‐prone ecosystems, which despite diverse objectives, has allowed human societies to cope with fire as a recurrent disturbance. 相似文献
1000.