全文获取类型
收费全文 | 268篇 |
免费 | 18篇 |
国内免费 | 1篇 |
出版年
2021年 | 4篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 9篇 |
2013年 | 6篇 |
2012年 | 13篇 |
2011年 | 9篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 15篇 |
2007年 | 15篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 8篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1964年 | 3篇 |
1963年 | 3篇 |
1962年 | 1篇 |
1961年 | 2篇 |
1957年 | 2篇 |
1956年 | 3篇 |
1933年 | 1篇 |
排序方式: 共有287条查询结果,搜索用时 78 毫秒
81.
Stoats are significant predators of native fauna in New Zealand. They occur in many habitat types and consume a wide range of prey. The diet of stoats in the Tasman River, South Canterbury, was studied by analysis of scats and den contents. Analysis of 206 scats showed that stoats ate mainly lagomorphs, birds and invertebrates. Minor components included mice, lizards, fish and hedgehogs. Stoats ate more birds in spring than in autumn, and female stoats ate more invertebrates than did males. The contents of 219 dens collected in the same area at the same time provided further information. Birds and lagomorphs occurred at high frequency in dens, and other components were minor. Remains in dens were larger than in scats and allowed identification of many more prey items to species level. Den contents revealed a potentially substantial impact of stoats on threatened shorebirds locally; this impact was not detected by analysis of scats. 相似文献
82.
Review of Primate Origins of Human Cognition and Behavior by Tetsuro Matsuzawa. Tokyo, Springer‐Verlag, 2001, xxi + 587 pp, 248 fig., 4 in color, $119.00. 相似文献
83.
Kateřina Kolaříková Jakub Horecký Marek Liška Martina Jíchová Jolana Tátosová Natálie Lapšanská Zuzana Hořická Pavel Chvojka Luboš Beran Vladimír Košel Josef Matěna Zuzana Čiamporová-Zaťovičová Iľja Krno Eva Bulánková Ferdinand Šporka Petr Kment Evžen Stuchlík 《Biologia》2014,69(4):508-521
In the Czech part of the Labe River and the lower part of the Vltava River, we examined if the benthic macroinvertebrate composition changed from 1996 to 2005 due to expected improvements in water quality resulting from socioeconomic changes in the Czech Republic since the 1990s. Special attention was given to rare and alien species. The four biological metrics used (Number of taxa, BMWP, Number of sensitive taxa, and Number of EPT taxa) demonstrated that there was indeed an improvement in water quality as well as a slight improvement of the Labe microhabitats during the investigated period. An increasing Number of taxa over time was observed at most sites. Two main concurrent ecological processes are recently in progress in the Labe: a recovery of native species and an expansion of alien species, some of which are considered invasive. The caddisfly Setodes punctatus and the beetle Pomatinus substriatus, considered as regionally extinct in the Czech Republic until 2005, were rediscovered during our investigations. Findings of the crustacean Hemimysis anomala (invasive) and the chironomids Stenochironomus sp. and Lipiniella sp. were the first records of these taxa in the Czech Republic. 相似文献
84.
T-helper 17 cell cytokines and interferon type I: partners in crime in systemic lupus erythematosus?
Zana Brkic Odilia BJ Corneth Cornelia G van Helden-Meeuwsen Radboud JEM Dolhain Naomi I Maria Sandra MJ Paulissen Nadine Davelaar Jan Piet van Hamburg Paul L van Daele Virgil A Dalm P Martin van Hagen Johanna MW Hazes Marjan A Versnel Erik Lubberts 《Arthritis research & therapy》2014,16(2):R62
Introduction
A hallmark of systemic autoimmune diseases like systemic lupus erythematosus (SLE) is the increased expression of interferon (IFN) type I inducible genes, so-called IFN type I signature. Recently, T-helper 17 subset (Th17 cells), which produces IL-17A, IL-17F, IL-21, and IL-22, has been implicated in SLE. As CCR6 enriches for Th17 cells, we used this approach to investigate whether CCR6+ memory T-helper cells producing IL-17A, IL-17F, IL-21, and/or IL-22 are increased in SLE patients and whether this increase is related to the presence of IFN type I signature.Methods
In total, 25 SLE patients and 15 healthy controls (HCs) were included. SLE patients were divided into IFN type I signature-positive (IFN+) (n = 16) and negative (IFN-) (n = 9) patients, as assessed by mRNA expression of IFN-inducible genes (IFIGs) in monocytes. Expression of IL-17A, IL-17F, IL-21, and IL-22 by CD4+CD45RO+CCR6+ T cells (CCR6+ cells) was measured with flow cytometry and compared between IFN+, IFN- patients and HCs.Results
Increased percentages of IL-17A and IL-17A/IL-17F double-producing CCR6+ cells were observed in IFN+ patients compared with IFN- patients and HCs. IL-17A and IL-17F expression within CCR6+ cells correlated significantly with IFIG expression. In addition, we found significant correlation between B-cell activating factor of the tumor necrosis family (BAFF)–a factor strongly correlating with IFN type I - and IL-21 producing CCR6+ cells.Conclusions
We show for the first time higher percentages of IL-17A and IL-17A/IL-17F double-producing CCR6+ memory T-helper cells in IFN+ SLE patients, supporting the hypothesis that IFN type I co-acts with Th17 cytokines in SLE pathogenesis. 相似文献85.
Kai Yu Zhang Angela E Kedgley Claire R Donoghue Daniel Rueckert Anthony MJ Bull 《Arthritis research & therapy》2014,16(1):R27
Introduction
The meniscus has an important role in force transmission across the knee, but a detailed three-dimensional (3D) morphometric shape analysis of the lateral meniscus to elucidate subject-specific function has not been conducted. The aim of this study was to perform 3D morphometric analyses of the lateral meniscus in order to correlate shape variables with anthropometric parameters, thereby gaining a better understanding of the relationship between lateral meniscus shape and its load-bearing function.Methods
The lateral meniscus (LM) was manually segmented from magnetic resonance images randomly selected from the Osteoarthritis Initiative (OAI) non-exposed control subcohort. A 3D statistical shape model (SSM) was constructed to extract the principal morphological variations (PMV) of the lateral meniscus for 50 subjects (25 male and 25 female). Correlations between the principal morphological variations and anthropometric parameters were tested. Anthropometric parameters that were selected included height, weight, body mass index (BMI), femoral condyle width and axial rotation.Results
The first principal morphological variation (PMV) was found to correlate with height (r = 0.569), weight (r = 0.647), BMI (r = 0.376), and femoral condyle width (r = 0.622). The third PMV was found to correlate with height (r = 0.406), weight (r = 0.312), and femoral condyle width (r = 0.331). The percentage of the tibial plateau covered by the lateral meniscus decreases as anthropometric parameters relating to size of the subject increase. Furthermore, when the size of the subject increases, the posterior and anterior horns become proportionally longer and wider.Conclusion
The correlations discovered suggest that variations in meniscal shape can be at least partially explained by the levels of loads transmitted across the knee on a regular basis. Additionally, as the size of the subject increases and body weight rises, the coverage percentage of the meniscus is reduced, suggesting that there would be an increase in the load-bearing by the cartilage. However, this reduced coverage percentage is compensated by the proportionally wider and longer meniscal horn. 相似文献86.
Jeňýk Hofmeister Jan Hošek Marek Brabec Daniel Dvořák Miroslav Beran Helena Deckerová Jiří Burel Martin Kříž Jan Borovička Jan Běťák Martina Vašutová 《Biodiversity and Conservation》2014,23(8):2015-2031
Macrofungal species richness generally increases with forest continuity as does the richness of so-called ancient forest plant species (AFS). Based on this assumption, we examined the ability of AFS to indicate macrofungal diversity in six study areas covering a range of elevations and environments in the Czech Republic. In total, we used data from 106 sampling plots (2,500 m2 each) distributed over six types of forest stands reflecting different intensities and temporal stages of forest management. Species composition of vascular plants and macrofungi was recorded by a single inventory and regular 2-year monitoring, respectively. In total, we found 71 AFS and 1,413 macrofungal species, of which 150 were red-listed macrofungal species. We documented that AFS show potential for being used in the prediction of macrofungi species richness, including endangered species, at the local scale (α-diversity). Additionally, we found significant differences in macrofungal species richness depending on study area and type of forest management, which did not, however, derogate the effect of AFS. Spatial congruence between species composition of AFS and macrofungi communities (β-diversity) increased with forest age and decreased with intensity of forest management. If we consider the simplicity of monitoring AFS in comparison to regular monitoring of macrofungi, we found a widely usable tool for estimating macrofungal diversity in all dominant types of managed forest in central Europe. However, we should be aware of the limited ability of AFS to capture macrofungal diversity across a broader spatial context (γ-diversity), especially in areas with a low diversity of AFS. 相似文献
87.
MJ Müller MP Mendon?a IR Oliveira LPL de Oliveira VLS Valente VH Valiati 《Neotropical Entomology》2012,41(2):112-120
We describe for the first time the sexual behavior and the courtship song of males of the African fly Zaprionus indianus (Gupta), a recent invader of South America. The male courtship song is formed by monocyclic pulses and the courtship behavior is simple when compared to that of species of Drosophila. Two interpulse interval (IPI) distributions were observed: pre-mounting and mounting. No significant difference was observed between the pre-mounting IPIs of males that descended from three geographical populations from South America. We also observed the songs produced by females and the homosexual behavior exhibited by males. A sequence of bursts is produced by females as a refusal signal against males, while males emit a characteristic song that identifies sex genus, which differs from the courtship song. The short courtship and mating latencies recorded reveal vigorous males and receptive females, respectively. 相似文献
88.
89.
The distribution of cercariae was studied in 18-cm-sized cuvettes under different lighting conditions, in Plexiglas cylinders (80 cm high) vertically placed in a pond, and when swimming freely in a pond. The vertical distribution and the effect of light intensity on it were relatively similar in the cuvettes, in the cylinders, and in the pond. Each of the species (Schistosoma mansoni, Diplostomum spathaceum, Echinostoma caproni, and Pseudechinoparyphium echinatum) showed its individual distribution within the water column, with distinct changes during the time after shedding. We hypothesize that the species-specific distributions in the water reflect behavioral adaptations to increase the chances of encountering the host spectra. 相似文献
90.
Hetty C van den Broeck Teun WJM van Herpen Cees Schuit Elma MJ Salentijn Liesbeth Dekking Dirk Bosch Rob J Hamer Marinus JM Smulders Ludovicus JWJ Gilissen Ingrid M van der Meer 《BMC plant biology》2009,9(1):41