全文获取类型
收费全文 | 391篇 |
免费 | 26篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 12篇 |
2018年 | 16篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 23篇 |
2014年 | 21篇 |
2013年 | 23篇 |
2012年 | 31篇 |
2011年 | 45篇 |
2010年 | 23篇 |
2009年 | 16篇 |
2008年 | 22篇 |
2007年 | 18篇 |
2006年 | 21篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 14篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1966年 | 2篇 |
1964年 | 1篇 |
1962年 | 3篇 |
1960年 | 3篇 |
1958年 | 1篇 |
1951年 | 1篇 |
1948年 | 1篇 |
排序方式: 共有417条查询结果,搜索用时 15 毫秒
51.
Group A streptococcus is a Gram-positive bacteria that causes a range of infectious diseases. Targeting the bacteria, a new self-adjuvanting vaccine candidate, incorporating a carbohydrate carrier and an amino acid-based adjuvant, was synthesised utilising carbohydrate chemistry and solid-phase peptide synthesis procedures. Characterisation of the candidate was achieved using reverse-phase HPLC and electrospray ionisation mass spectrometry. The successful synthesis and characterisation of the vaccine candidate may contribute to the discovery of a therapeutically and clinically viable vaccine against group A streptococcus. 相似文献
52.
The recurrent drying out of small streams in past decades has shown an urgent need to pay attention to the impact of global
climate change. The objectives of this study were to describe the effect of drying out on the composition of the mayfly taxocene
and evaluate the relevance of individual species traits for survival of mayflies to drying out. The mayfly taxocenes of two
model localities, one at an intermittent and one at a permanent brook, were investigated in 2002, 2003 and 2005. Compared
with the permanent stream, the taxocene of the intermittent stream was short of nine species, foremost rheobionts and high
oxygen demand species. To explain further differences between both stream types in survival and recolonisation ability, 15
species traits were evaluated. These included so-called “ecological traits” (e.g., habitat and substrate range, density, distribution,
current velocity adaptation) and “biological traits” connected with life cycle and larval/adult adaptations. Species showing
the highest number of advantageous traits (with only exception of Electrogena sp. cf. ujhelyii — species of taxonomically unclear status) were able to successfully survive under the unfavourable conditions of the intermittent
brook. Biological traits considered more important in many respects seem to be good predictors for assessing sensitivity to
extreme temperature changes, hydrological regime fluctuations and the survival/recolonisation ability of species in exposed
habitats. 相似文献
53.
54.
Evaluation and indirect estimation of nitrate losses from the agricultural microbasin Rybárik 总被引:1,自引:0,他引:1
The long-term trends of mean monthly nitrate concentrations in stream and drainage runoff were evaluated in the experimental
microbasin Rybárik (0.119 km2) at the Institute of Hydrology, Slovak Academy of Sciences, during the period 1987–2005. The results of analyses indicate
a decreasing trend of nitrate concentration after the year 1989, but with relatively high losses in some years and relatively
low losses in other years. This decreasing trend is mainly caused by a decrease in the use of nitrogen fertilizers. The nitrate
concentration in surface runoff strongly correlates with runoff and fertilization. Based on measured data, an empirical relation
was found describing the dependence of annual nitrate transport in the stream on annual runoff depth and on the annual amount
of applied nitrogen fertilizers.
Presented at the International Conference on Bioclimatology and Natural Hazards, Poľana nad Detvou, Slovakia, 17–20 September
2007. 相似文献
55.
Aryl sulfamates were originally developed as inhibitors of steroid sulfatase, and have recently been shown to be powerful inactivators of a bacterial sulfatase, PaAtsA from Pseudomonas aeruginosa. We demonstrate that a simple aryl sulfamate, 3-nitrophenyl sulfamate, can inactivate sulfatases from various sources including snail, limpet and abalone. In each case inactivation was time-dependent and active-site directed, as demonstrated by protection against inactivation by substrate. These results suggest that such easily acquired aryl sulfamates can be used as reliable biochemical reagents for the study of sulfatases from a diverse array of sources. 相似文献
56.
57.
58.
Phenological sensitivity to climate change is higher in resident than in migrant bird populations among European cavity breeders
下载免费PDF全文
![点击此处可从《Global Change Biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jelmer M. Samplonius Lenka Bartošová Malcolm D. Burgess Andrey V. Bushuev Tapio Eeva Elena V. Ivankina Anvar B. Kerimov Indrikis Krams Toni Laaksonen Marko Mägi Raivo Mänd Jaime Potti János Török Miroslav Trnka Marcel E. Visser Herwig Zang Christiaan Both 《Global Change Biology》2018,24(8):3780-3790
Many organisms adjust their reproductive phenology in response to climate change, but phenological sensitivity to temperature may vary between species. For example, resident and migratory birds have vastly different annual cycles, which can cause differential temperature sensitivity at the breeding grounds, and may affect competitive dynamics. Currently, however, adjustment to climate change in resident and migratory birds have been studied separately or at relatively small geographical scales with varying time series durations and methodologies. Here, we studied differential effects of temperature on resident and migratory birds using the mean egg laying initiation dates from 10 European nest box schemes between 1991 and 2015 that had data on at least one resident tit species and at least one migratory flycatcher species. We found that both tits and flycatchers advanced laying in response to spring warming, but resident tit populations advanced more strongly in relation to temperature increases than migratory flycatchers. These different temperature responses have already led to a divergence in laying dates between tits and flycatchers of on average 0.94 days per decade over the current study period. Interestingly, this divergence was stronger at lower latitudes where the interval between tit and flycatcher phenology is smaller and winter conditions can be considered more favorable for resident birds. This could indicate that phenological adjustment to climate change by flycatchers is increasingly hampered by competition with resident species. Indeed, we found that tit laying date had an additional effect on flycatcher laying date after controlling for temperature, and this effect was strongest in areas with the shortest interval between both species groups. Combined, our results suggest that the differential effect of climate change on species groups with overlapping breeding ecology affects the phenological interval between them, potentially affecting interspecific interactions. 相似文献
59.
Interaction of leukemia blasts with the bone marrow extracellular matrix often results in protection of leukemia cells from chemotherapy and in persistence of the residual disease which is on the basis of subsequent relapses. The adhesion signaling pathways have been extensively studied in adherent cells as well as in mature haematopoietic cells, but the adhesion structures and signaling in haematopoietic stem and progenitor cells, either normal or malignant, are much less explored. We analyzed the interaction of leukemia cells with fibronectin (FN) using interference reflection microscopy, immunofluorescence, measurement of adherent cell fraction, real-time microimpedance measurement and live cell imaging. We found that leukemia cells form very dynamic adhesion structures similar to early stages of focal adhesions. In contrast to adherent cells, where Src family kinases (SFK) belong to important regulators of focal adhesion dynamics, we observed only minor effects of SFK inhibitor dasatinib on leukemia cell binding to FN. The relatively weak involvement of SFK in adhesion structure regulation might be associated with the lack of cytoskeletal mechanical tension in leukemia cells. On the other hand, active Lyn kinase was found to specifically localize to leukemia cell adhesion structures and a less firm cell attachment to FN was often associated with higher Lyn activity (this unexpectedly occurred also after cell treatment with the inhibitor SKI-1). Lyn thus may be important for signaling from integrin-associated complexes to other processes in leukemia cells. 相似文献
60.
Invasive round goby Neogobius melanostomus has sex‐dependent locomotor activity and is under‐represented in catches from passive fishing gear compared with seine catches
下载免费PDF全文
![点击此处可从《Journal of fish biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jakub Žák Tomáš Jůza Petr Blabolil Roman Baran Daniel Bartoň Vladislav Draštík Jaroslava Frouzová Michaela Holubová Henk A. M. Ketelaars Luboš Kočvara Jan Kubečka Tomáš Mrkvička Milan Muška Milan Říha Zuzana Sajdlová Marek Šmejkal Michal Tušer Mojmír Vašek Lukáš Vejřík Ivana Vejříková Arco J. Wagenvoort 《Journal of fish biology》2018,93(1):147-152
The higher proportion of males of the invasive round goby Neogobius melanostomus in samples from two activity selective passive fishing gears compared with one activity non‐selective fishing gear in three Dutch lakes is related to higher male locomotory activity and is a sex‐dependent trait. This difference in activity reflects the different ecology of male and female N. melanostomus. 相似文献