全文获取类型
收费全文 | 465篇 |
免费 | 15篇 |
国内免费 | 8篇 |
出版年
2020年 | 3篇 |
2018年 | 4篇 |
2017年 | 8篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 10篇 |
2012年 | 17篇 |
2011年 | 11篇 |
2010年 | 16篇 |
2009年 | 16篇 |
2008年 | 20篇 |
2007年 | 12篇 |
2006年 | 17篇 |
2005年 | 10篇 |
2004年 | 14篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 5篇 |
1999年 | 11篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 12篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1992年 | 7篇 |
1988年 | 3篇 |
1986年 | 3篇 |
1983年 | 5篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1966年 | 2篇 |
1959年 | 7篇 |
1958年 | 23篇 |
1957年 | 26篇 |
1956年 | 26篇 |
1955年 | 22篇 |
1954年 | 22篇 |
1953年 | 13篇 |
1952年 | 13篇 |
1951年 | 10篇 |
1950年 | 9篇 |
1949年 | 2篇 |
1948年 | 2篇 |
1912年 | 2篇 |
排序方式: 共有488条查询结果,搜索用时 565 毫秒
91.
G. A. Danchinova N. V. Yakovchits A. V. Liapunov N. V. Kulakova H. V. Dubinina M. A. Khasnatinov 《Entomological Review》2018,98(3):369-374
The dynamics of development of the population of taiga ticks Ixodes persulcatus Schulze, 1930 from Eastern Siberia was studied under experimental conditions. Ticks were reared at 23–25°C, relative humidity of 80–90%, and a light: darkness ratio of 16: 8 h. The mean time of egg incubation was 35.2 days; the feeding of females, larvae, and nymphs took 6.4, 3.5, and 4.5 days, respectively. The existence of two subpopulations, differing in the time of development of engorged larvae into nymphs and nymphs into adults, was experimentally demonstrated. Most ticks had short periods of larval and nymphal development that lasted 25 ± 2 and 40 ± 4 days, respectively. However, some ticks exhibited prolonged development time of 75.5 ± 2 and 95 ± 9 days, respectively. The total duration of the life cycle was 121 days in the former group and 226 days in the latter group. 相似文献
92.
A. G. DE LA FILIA S. ANDREWES J. M. CLARK L. ROSS 《Medical and veterinary entomology》2018,32(2):226-234
Insect reproduction is extremely variable, but the implications of alternative genetic systems are often overlooked in studies on the evolution of insecticide resistance. Both ecotypes of Pediculus humanus (Phthiraptera: Pediculidae), the human head and body lice, are human ectoparasites, the control of which is challenged by the recent spread of resistance alleles. The present study conclusively establishes for the first time that both head and body lice reproduce through paternal genome elimination (PGE), an unusual genetic system in which males transmit only their maternally derived chromosomes. Here, we investigate inheritance patterns of parental genomes using a genotyping approach across families of both ecotypes and show that heterozygous males exclusively or preferentially pass on one allele only, whereas females transmit both in a Mendelian fashion. We do however observe occasional transmission of paternal chromosomes through males, representing the first known case of PGE in which whole‐genome meiotic drive is incomplete. Finally, we discuss the potential implications of this finding for the evolution of resistance and invite the development of new theoretical models of how this knowledge might contribute to increasing the success of pediculicide‐based management schemes. 相似文献
93.
Fruit morphology in Tragopogon L. (Compositae: Lactuceae) from the Iberian Peninsula 总被引:2,自引:0,他引:2
G. BLANCA C. DÍAZ DE LA GUARDIA 《Botanical journal of the Linnean Society. Linnean Society of London》1997,125(4):319-329
Achenes of all the Tragopogon species from the Iberian Peninsula were examined by means of scanning-electron microscopy and stereomicroscopy. The achenes of the eight species are described, illustrated and compared. The results are contrasted with the systematics of this genus. The isolated position of T. lamottei with regard to the other seven species is noted. A key is provided to enable the different species to be distinguished. 相似文献
94.
First record in America of Aedes albopictus naturally infected with dengue virus during the 1995 outbreak at Reynosa, Mexico 总被引:2,自引:0,他引:2
SERGIO IBÁÑEZ-BERNAL BALTASAR BRISEÑO JOHN PAUL MUTEBI ENID ARGOT GUADALUPE RODRÍGUEZ CARMEN MARTINEZ-CAMPOS RAFAEL PAZ PEDRO DE LA FUENTE-SAN ROMÁN† ROBERTO TAPIA-CONYER‡ ANA FLISSER 《Medical and veterinary entomology》1997,11(4):305-309
Abstract Mosquito collections were conducted during a dengue outbreak in Reynosa, Tamaulipas, Mexico, July-December 1995. A total of 6694 adult mosquitoes (four genera and nine species) were captured, of which 2986 (78.3% females and 21.7% males) were Aedes albopictus and 2339 (39.7% females and 60.3% males) were Ae.aegypti. These two species comprised 84.2% of the total collection. Specimens were grouped into pools, nearly 50% of them processed for detection of virus by cythopathic effect in C6-36 and VERO cell cultures and by haemagglutination test. Five pools gave positive haemagglutin-ation reactions and were examined by immunofluorescence using monoclonal antibodies to flavivirus and to dengue virus. One pool of ten Ae.albopictus males was positive for dengue virus: serotypes 2 and 3 were identified by serotype-specific monoclonal antibodies arid confirmed by RT-PCR. This is the first report of Ae.albopictus naturally infected with dengue virus in America. Also, it is the very first time Ae.albopictus males have been found infected with dengue virus in the wild. 相似文献
95.
96.
The nature of the defect in tyrosine metabolism in alcaptonuria 总被引:12,自引:0,他引:12
97.
98.
99.
100.