全文获取类型
收费全文 | 349篇 |
免费 | 35篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 17篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 16篇 |
2012年 | 23篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 13篇 |
2008年 | 16篇 |
2007年 | 11篇 |
2006年 | 17篇 |
2005年 | 11篇 |
2004年 | 17篇 |
2003年 | 13篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 4篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1969年 | 6篇 |
1958年 | 2篇 |
排序方式: 共有384条查询结果,搜索用时 390 毫秒
81.
Phage Typing Reactions on Brucella Species 总被引:1,自引:0,他引:1
The nature of the phage typing reactions on Brucella species was determined by rates of adsorption and infection, one-step growth experiments, and susceptibility to lysis from without. The highest rates of adsorption and infection were obtained on smooth B. abortus cultures, and large clear plaques were produced. One or a few phage particles per B. neotomae cell killed about one-half of the cells, but some went through an infective cycle and released mature phage that resulted in production of small clear plaques. With B. suis, more phage particles per cell were required to kill, replication did not occur, and plaques were not observed. Still greater numbers of phage particles were required to cause some inhibition of growth of B. melitensis lawns. Rough Brucella cultures and species, such as B. ovis and B. canis, were not affected by the highest concentrations of phage. B. abortus cultures of intermediate colonial morphology adsorbed phage, but only a few infected cells (after a delayed latent period) released mature phage. An infected culture or colony appeared normal until spontaneous phage mutants appeared which could penetrate the cell wall more effectively than the parent phage. The mutant phage multiplied more rapidly, and the colony changed to a sticky white form. 相似文献
82.
83.
P. Kurnath N. D. Merz M. D. Dearing 《Proceedings. Biological sciences / The Royal Society》2016,283(1822)
Growing evidence suggests that plant secondary compounds (PSCs) ingested by mammals become more toxic at elevated ambient temperatures, a phenomenon known as temperature-dependent toxicity. We investigated temperature-dependent toxicity in the desert woodrat (Neotoma lepida), a herbivorous rodent that naturally encounters PSCs in creosote bush (Larrea tridentata), which is a major component of its diet. First, we determined the maximum dose of creosote resin ingested by woodrats at warm (28–29°C) or cool (21–22°C) temperatures. Second, we controlled the daily dose of creosote resin ingested at warm, cool and room (25°C) temperatures, and measured persistence in feeding trials. At the warm temperature, woodrats ingested significantly less creosote resin; their maximum dose was two-thirds that of animals at the cool temperature. Moreover, woodrats at warm and room temperatures could not persist on the same dose of creosote resin as woodrats at the cool temperature. Our findings demonstrate that warmer temperatures reduce PSC intake and tolerance in herbivorous rodents, highlighting the potentially adverse consequences of temperature-dependent toxicity. These results will advance the field of herbivore ecology and may hone predictions of mammalian responses to climate change. 相似文献
84.
85.
86.
Ellen Merz 《Primates; journal of primatology》1978,19(4):749-754
Infants ofMacaca sylvanus are often involved in male-male interactions. Very similar interactions occur also with dead infants. The present paper describes
male-male interactions with dead infants and emphasizes similarities and differences between these and those involving live
infants. Causation is also briefly discussed. 相似文献
87.
Human choriogonadotropin (hCG) analogues, containing the native beta-subunit and alpha-subunits enzymatically shortened by 2-3 amino acid residues, were used for studying the influence of hCG on the content of microsomal progesterone-binding cytochrome P-450 in rat testis. When 2-3 residues have been removed from the alpha-subunit, the ability of the hormone analogue to stimulate adenylate cyclase of isolated rat Leydig cells was diminished by 55%. When the hCG analogue containing a des-(88-92)-alpha chain was applied, the residual activity of the adenylate cyclase was negligible. 18 h after administration to rats in vivo, the hormone species containing des-(Lys-91-Ser-92)-alpha or des-(90-92)-alpha, respectively, were found to have induced a decrease in microsomal cytochrome P-450 content with an effectiveness corresponding to their ability of stimulating the adenylate cyclase in vitro. However, when assayed 48 h after application, the desensitization of the microsomal cytochrome P-450 system had persisted in case of the hCG species containing a des-(90-92)-alpha chain but not in case of hCG consisting of des-(Lys-91-Ser-92)-alpha and a native beta-subunit. From these results, it is concluded that short-term effects of hCG on the microsomal content of progesterone-binding cytochrome P-450 are mediated by the stimulation of adenylate cyclase. In contrast, the long-lasting action of hCG on this system seems not to be exclusively mediated by the increase in intracellular cAMP. 相似文献
88.
Andrade Elisa Helena Paz Figueiredo Leandra Barcelos Vilela Ana Paula Pessoa Rosa Jlio Csar Cmara Zibaoui Hassan Melo Kroon Erna Geessien 《EcoHealth》2022,19(1):75-84
EcoHealth - Dengue virus (DENV) 1–4 is the etiological agent of dengue, the most important viral infection transmitted by Aedes spp mosquitoes to humans. Our goal was to identify the... 相似文献
89.
90.
Maria Leandra Terencio Carlos Henrique Schneider Maria Claudia Gross Marcelo Ricardo Vicari Eliana Feldberg 《Hydrobiologia》2012,686(1):147-156
Cytogenetic studies involving the family Prochilodontidae have shown that these fish can be characterized by a constant diploid
number and a conserved karyotypic macrostructure. This study focused on comparative physical chromosomal mapping using 18S
and 5S rDNA to compare the species Semaprochilodus insignis and S. taeniurus. Our results indicated the conservation of large number of conventional chromosomal markers. The molecular cytogenetic analyses
of the location of the 18S rDNA indicated the maintenance of a chromosome pair bearing these sites in both species analyzed,
and it appears to be a conserved character among the majority of the species of this family. The stability of the number of
5S ribosomal DNA sites and their chromosomal localization as has been reported for the Prochilodontidae was not, however,
confirmed for S. insignis and S. taeniurus, as these species showed multiple specific rDNA 5S sites. As such, and in spite of the fact that a number of studies indicate
that the family Prochilodontidae has a conserved karyotypic structure, the utilization of molecular tools that use chromosomal
segments as markers revealed that this presumed stability cannot be extended to the genome level for the species S. insignis and S. taeniurus. 相似文献