全文获取类型
收费全文 | 2759篇 |
免费 | 122篇 |
出版年
2021年 | 20篇 |
2020年 | 17篇 |
2019年 | 23篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 35篇 |
2015年 | 73篇 |
2014年 | 78篇 |
2013年 | 164篇 |
2012年 | 120篇 |
2011年 | 110篇 |
2010年 | 77篇 |
2009年 | 80篇 |
2008年 | 91篇 |
2007年 | 104篇 |
2006年 | 100篇 |
2005年 | 100篇 |
2004年 | 65篇 |
2003年 | 69篇 |
2002年 | 68篇 |
2001年 | 32篇 |
2000年 | 21篇 |
1999年 | 24篇 |
1998年 | 31篇 |
1997年 | 32篇 |
1996年 | 27篇 |
1995年 | 26篇 |
1993年 | 21篇 |
1992年 | 18篇 |
1991年 | 16篇 |
1988年 | 23篇 |
1987年 | 29篇 |
1986年 | 25篇 |
1985年 | 28篇 |
1984年 | 27篇 |
1982年 | 29篇 |
1981年 | 27篇 |
1980年 | 17篇 |
1978年 | 17篇 |
1977年 | 15篇 |
1972年 | 16篇 |
1970年 | 19篇 |
1968年 | 18篇 |
1966年 | 18篇 |
1965年 | 16篇 |
1963年 | 16篇 |
1961年 | 20篇 |
1958年 | 19篇 |
1885年 | 14篇 |
1880年 | 14篇 |
排序方式: 共有2881条查询结果,搜索用时 31 毫秒
41.
K. Zengler Johann Heider Ramon Rosselló-Mora Friedrich Widdel 《Archives of microbiology》1999,172(4):204-212
The capacity of anoxygenic phototrophic bacteria to utilize aromatic hydrocarbons was investigated in enrichment cultures
with toluene. When mineral medium with toluene (provided in an inert carrier phase) was inoculated with activated sludge and
incubated under infrared illumination (> 750 nm), a red-to-brownish culture developed. Agar dilution series indicated the
dominance of two types of phototrophic bacteria. One type formed red colonies, had rod-shaped cells with budding division,
and grew on benzoate but not on toluene. The other type formed yellow-to-brown colonies, had oval cells, and utilized toluene
and benzoate. One strain of the latter type, ToP1, was studied in detail. Sequence analysis of the 16S rRNA gene and DNA-DNA
hybridization indicated an affiliation of strain ToP1 with the species Blastochloris sulfoviridis, a member of the α-subclass of Proteobacteria. However, the type strain (DSM 729) of Blc. sulfoviridis grew neither on toluene nor on benzoate. Light-dependent consumption of toluene in the presence of carbon dioxide and formation
of cell mass by strain ToP1 were demonstrated in quantitative growth experiments. Strain ToP1 is the first phototrophic bacterium
shown to utilize an aromatic hydrocarbon. In the supernatant of toluene-grown cultures and in cell-free extracts incubated
with toluene and fumarate, the formation of benzylsuccinate was detected. These findings indicate that the phototrophic bacterium
activates toluene anaerobically by the same mechanism that has been reported for denitrifying and sulfate-reducing bacteria.
The natural abundance of phototrophic bacteria with the capacity for toluene utilization was examined in freshwater habitats.
Counting series revealed that up to around 1% (1.8 × 105 cells per gram dry mass of sample) of the photoheterotrophic population cultivable with acetate grew on toluene.
Received: 29 March 1999 / Accepted: 1 July 1999 相似文献
42.
43.
Michel Adamina Reto Schumacher Paul Zajac Walter P. Weber Rachel Rosenthal Célia Groeper 《Journal of liposome research》2013,23(3):195-204
Malignant tumors represent a major source of disability and account for more than one of five deaths in Western countries. Among the different cancers, melanoma harbors two distinctive features. First, its has long been recognized as an immunogenic tumor, and second, an unprecedented rise in incidence is currently observed, in face of few therapeutic options. Thus, melanoma represent an ideal target for a cancer immunotherapy program. To date, a number of immunodominant epitopes from tumor associated antigens (TAA) are used as cancer vaccines in clinical trials, in spite of an acknowledged rapid degradation in vivo and low immunogenicity. However, most of the immunotherapy trials reported so far do not achieve consistent clinical results. Hence, there is an urgent need for the development of a carrier system and strong adjuvants suitable for a TAA-based cancer immunotherapy. Liposomes and their further development as virosomes with added adjuvancy may address both these issues. We report here our experience in the tailoring of dedicated advanced liposomal vectors that were developed in the context of an upcoming immunotherapy clinical trial for melanoma. 相似文献
44.
E. Bezzel S. Schuster K. Immelmann H. Remmert W. Scherzinger G. Niethammer P. Berthold und G. Diesselhorst 《Journal of Ornithology》1973,114(3):361-367
Ohne Zusammenfassung 相似文献
45.
Ohne Zusammenfassung 相似文献
46.
Johann v. Csató 《Plant Systematics and Evolution》1886,36(7):246-247
Ohne Zusammenfassung 相似文献
47.
Rolf Erhard und Michael Wink 《Journal of Ornithology》1987,128(4):477-484
Zusammenfassung Die Brutverbreitung der Vögel im Großraum Bonn wurde 1975 und 1985 in jeweils 221 Minutengitterfeldern von je 2,2 km2 Größe kartiert. Statistisch signifikante Zunahmen besetzter Gitterfelder wurden für 9 Arten, Abnahmen für 22 Arten registriert, die z. T. auch andernorts festgestellt wurden. Unter Verwendung von Kartierungsdaten 1974–1978 konnte bei 14 Arten eine signifikante Änderung (Zunahmen: Sperber, Habicht, Singdrossel; Abnahmen: Steinschmätzer, Rebhuhn, Schafstelze, Grauammer, Mehlschwalbe, Feldsperling, Fasan, Dorngrasmücke, Hänfling, Feldlerche und Zaunkönig) nachgewiesen werden. Die Untersuchung zeigt, daß die Rasterkartierung gut geeignet ist, Aussagen über großflächige und langfristige Populationsveränderungen zu machen.
Fluctuation of breeding populations in the area of Bonn: Analysis of grid mapping in 1975 and 1985
Summary The distribution of breeding birds in the area of Bonn was mapped in 1975 and 1985 in 221 grids of 2.2 km2 size each. These data were analyzed to see whether fluctuations in the breeding populations occurred during the 11 years. It was based on the assumption that strong population changes should be reflected in the number of grids occupied by a species. Statistically significant increases were recorded for 9 species, decreases for 22 species. Taking other grid-map data from 1974 til 1978 (Wink 1980) into account, a continuous and significant trend could be established for 14 species (increase:Accipiter nisus, A. gentilis, Turdus philomelos; decrease:Oenanthe oenanthe, Perdix perdix, Motacilla flava, Emberiza calandra, Delichon urbica, Passer montanus, Phasianus colchicus, Sylvia communis, Acanthis cannabina, Alauda arvensis, Troglodytes troglodytes). This study shows that grid-mapping may provide valuable data on population trends of breeding birds.相似文献
48.
H. Stein und V. v. Weizsäcker 《Reviews of Physiology, Biochemistry and Pharmacology》1928,27(1):657-708
Ohne Zusammenfassung 相似文献
49.
V. Haecker und Steinmann 《Molecular & general genetics : MGG》1908,1(1):461-468
Ohne Zusammenfassung 相似文献
50.
E. Bezzel und W. Baumgart 《Journal of Ornithology》1991,132(1):105-113
Ohne Zusammenfassung 相似文献