全文获取类型
收费全文 | 310篇 |
免费 | 20篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 12篇 |
2015年 | 18篇 |
2014年 | 16篇 |
2013年 | 15篇 |
2012年 | 26篇 |
2011年 | 13篇 |
2010年 | 17篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 16篇 |
2006年 | 9篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1995年 | 2篇 |
1993年 | 5篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 4篇 |
1974年 | 9篇 |
1973年 | 4篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1966年 | 1篇 |
1931年 | 2篇 |
1930年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有330条查询结果,搜索用时 0 毫秒
321.
Nikolas P. Johnston Marcin Piwczyński Paulina Trzeciak Kinga Walczak Krzysztof Szpila 《Systematic Entomology》2023,48(2):296-315
The Polleniidae (Diptera) are a family of flies best known for species of the genus Pollenia, which overwinter inside human dwellings. Previously divided across the Calliphoridae, Tachinidae and Rhinophoridae, the polleniid genera have only recently been united. Several studies have utilized molecular data to analyse polleniid phylogenetic relationships, although all have suffered from low taxon sampling or insufficient phylogenetic signal in molecular markers. To alleviate these problems, we utilized two automated organellar genome extraction software, GetOrganelle and MitoFinder, to assemble mitogenomes from genome skimming data from 22 representatives of the polleniid genera: Dexopollenia, Melanodexia, Morinia, Pollenia and Xanthotryxus. From these analyses, we provide 14 new mitogenomes for the Polleniidae and perform phylogenetic analyses of 13 protein-coding mitochondrial genes using both maximum likelihood and Bayesian inference. Subfamilial phylogenetic relationships within the Polleniidae are interrogated and Pollenia is found to form a monophyletic clade sister to Melanodexia, Morinia and Dexopollenia, providing no evidence for the synonymisation of any of these genera. Our topology conflicts with previous morphology-based cladistic interpretations, with the amentaria, griseotomentosa, semicinerea and viatica species-groups resolving as non-monophyletic. We provide support for our topology through analysis of adult morphology and male and female terminalia, while identifying new diagnostic characters for some of the clades of the Pollenia. To test the validity of the current diagnostic morphology in the Polleniidae, newly assembled cytochrome C oxidase subunit 1 (COI) data are combined with a polleniid COI barcode reference library and analysed using the species delimitation software ASAP. COI barcodes support the current morphologically defined species within the Pollenia. 相似文献
322.
Nikolas Berovic David J. Parker Michael D. Smith 《European biophysics journal : EBJ》2009,38(4):427-435
The bioluminescence produced by luciferase, a firefly enzyme, requires three substrates: luciferin, ATP and oxygen. We find
that ionizing radiation, in the form of a proton beam from a cyclotron, will eliminate dissolved oxygen prior to any damage
to other substrates or to the protein. The dose constant for removal of oxygen is 70 ± 20 Gy, a much smaller dose than required
to cause damage to protein. Removal of oxygen, which is initially in excess, leads to a sigmoidal response of bioluminescence
to radiation dose, consistent with a Michaelis–Menten relationship to substrate concentration. When excess oxygen is exhausted,
the response becomes exponential. Following the irradiation, bioluminescence recovers due to a slow leak of oxygen into the
solution. This may also explain previous observations on the response of bioluminescent bacteria to radiation. We have studied
the dependence of the reaction rate on enzyme and substrate concentration and propose a model for the reaction pathway consistent
with this data. The light output from unirradiated samples decreases significantly with time due to product inhibition. We
observe that this inhibition rate changes dramatically immediately after a sample is exposed to the beam. This sudden change
of the inhibition rate is unexplained but shows that enzyme regulatory function responds to ionizing radiation at a dose level
less than 0.6 Gy. 相似文献
323.
324.
Roger D. Pechous Vijay Sivaraman Paul A. Price Nikolas M. Stasulli William E. Goldman 《PLoS pathogens》2013,9(10)
Inhalation of Yersinia pestis causes primary pneumonic plague, a highly lethal syndrome with mortality rates approaching 100%. Pneumonic plague progression is biphasic, with an initial pre-inflammatory phase facilitating bacterial growth in the absence of host inflammation, followed by a pro-inflammatory phase marked by extensive neutrophil influx, an inflammatory cytokine storm, and severe tissue destruction. Using a FRET-based probe to quantitate injection of effector proteins by the Y. pestis type III secretion system, we show that these bacteria target alveolar macrophages early during infection of mice, followed by a switch in host cell preference to neutrophils. We also demonstrate that neutrophil influx is unable to limit bacterial growth in the lung and is ultimately responsible for the severe inflammation during the lethal pro-inflammatory phase. 相似文献
325.
Sound localization was investigated in a large pond open to a bay and similar to the normal environment of the animals. Observations were made of fish movements towards one of two underwater loud-speakers emitting squirrelfish alarm calls normally produced in response to predators. When the sound source was within 2·0 m of the test cage housing the fish, the subjects faced and moved toward the speaker. The animals responded some of the time when the source was within 3·0 m but generally did not orient to the sound source when the speaker was beyond 3·0 m. Response loss was correlated with the fish being in the acoustic far-field. Possible cues which release and direct localization remain unknown, but include particle velocity information alone, or some change in particle velocity: pressure relationships. 相似文献
326.
327.
328.
329.
Tissue expression of the vesicle protein pantophysin 总被引:3,自引:0,他引:3
Reinhard Windoffer Monika Borchert-Stuhlträger Nikolas K. Haass Sabine Thomas Michaela Hergt Clemens J. Bulitta R. E. Leube 《Cell and tissue research》1999,296(3):499-510
The cell-type restricted expression of cytoplasmic microvesicle membrane protein isoforms may be a consequence of the functional adaptation of these vesicles to the execution of specialized processes in cells of different specialization. To characterize the expression of the vesicle protein pantophysin, an isoform of the synaptic vesicle proteins synaptophysin and synaptoporin, we have prepared and characterized antibodies useful for the immunological detection of pantophysin in vitro and in situ. Using these reagents, we show by immunoblot analyses that pantophysin expression is not homogeneous but differs significantly between various bovine tissues. Furthermore, these differences are not exactly paralleled by the expression of other vesicle proteins of the SCAMP (secretory carrier-associated membrane protein) and VAMP (vesicle-associated membrane protein) types that have previously been localized to pantophysin vesicles in cultured cells. By immunofluorescence microscopy, pantophysin expression is seen predominantly in non-neuroendocrine cells with pronounced membrane traffic. Pantophysin staining codistributes with SCAMP and VAMP immunoreactivities in most instances but differs in some. Remarkably, pantophysin staining in liver is restricted to cells surrounding sinusoids and is not detectable in hepatocytes, similar to that of the SCAMP and VAMP isoforms as detected by our reagents in tissue sections. 相似文献
330.
Amplification of kinetoplast DNA as a tool in the detection and diagnosis of Leishmania 总被引:10,自引:0,他引:10
This paper demonstrates how the polymerase chain reaction can be used to increase the sensitivity of detection of Leishmania parasites by DNA hybridization methods through the amplification of the minicircle target sequence. The oligonucleotide primers used are able to direct the amplification of all Leishmania strains tested. In addition, the PCR products from L. mexicana and L. braziliensis strains can be distinguished by hybridization with kDNA probes. The method is sensitive enough to detect the kDNA from a single organism and this sensitivity allows the use of nonradioactive hybridization methods. This method can be used to detect Leishmania from human biopsy material. 相似文献