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Background
In August 2006 a major epidemic of bluetongue virus serotype 8 (BTV8) started off in North-West Europe. In the course of 2007 it became evident that BTV8 had survived the winter in North-West Europe, re-emerged and spread exponentially. Recently, the European Union decided to start vaccination against BTV8. In order to improve the understanding of the epidemiological situation, it was necessary to execute a cross-sectional serological study at the end of the BT vector season. Cattle were the target species for cross-sectional serological studies in Europe at the end of 2006 and 2007. However, there was no information on the BTV8-seroprevalence in sheep and goats. 相似文献53.
Ross EA Freeman S Zhao Y Dhanjal TS Ross EJ Lax S Ahmed Z Hou TZ Kalia N Egginton S Nash G Watson SP Frampton J Buckley CD 《PloS one》2008,3(6):e2338
Although the expression of PECAM-1 (CD31) on vascular and haematopoietic cells within the bone marrow microenvironment has been recognized for some time, its physiological role within this niche remains unexplored. In this study we show that PECAM-1 influences steady state hematopoietic stem cell (HSC) progenitor numbers in the peripheral blood but not the bone marrow compartment. PECAM-1(-/-) mice have higher levels of HSC progenitors in the blood compared to their littermate controls. We show that PECAM-1 is required on both progenitors and bone marrow vascular cells in order for efficient transition between the blood and bone marrow to occur. We have identified key roles for PECAM-1 in both the regulation of HSC migration to the chemokine CXCL12, as well as maintaining levels of the matrix degrading enzyme MMP-9 in the bone marrow vascular niche. Using intravital microscopy and adoptive transfer of either wild type (WT) or PECAM-1(-/-) bone marrow precursors, we demonstrate that the increase in HSC progenitors in the blood is due in part to a reduced ability to migrate from blood to the bone marrow vascular niche. These findings suggest a novel role for PECAM-1 as a regulator of resting homeostatic progenitor cell numbers in the blood. 相似文献
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A New Marine Reptile (Sauropterygia) from New Zealand: Further Evidence for A Late Cretaceous Austral Radiation of Cryptoclidid Plesiosaurs 总被引:1,自引:0,他引:1
Kaiwhekea katiki gen. et sp. nov. represents the first described cryptoclidid plesiosaurian from New Zealand. It is one of the largest cryptoclidids known, at a length of over 6.5 m, and represents the third reported genus of austral Late Cretaceous cryptoclidids. Kaiwhekea katiki is from siltstones of the Katiki Formation, upper Haumurian Stage (Cenomanian–Maastrichtian; c. 69–70 Ma) of coastal Otago, South Island, New Zealand. In the Late Cretaceous, the locality lay close to the polar circle. The holotype and only known specimen is an articulated skeleton with skull, preserved mostly as natural molds, but which lacks the forelimbs and pectoral girdle. The skull is relatively large and possesses several distinct characters, including a substantial, deep, jugal. There are about 43 upper and 42 lower teeth in each jaw quadrant; all are homodont, slim, and slightly recurved, lacking prominent ornament. Kaiwhekea probably took single soft-bodied prey. Based on cranial structure, it clearly belongs with the Cryptoclididae, but is not certainly close to the southern Late Cretaceous cryptoclidids Morturneria (Seymour Island, Antarctica) and Aristonectes (Chile, Argentina). 相似文献
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The contribution of flight capability to the post‐fledging dependence period of golden eagles 下载免费PDF全文
Ewan D. Weston D. Philip Whitfield Justin M. J. Travis Xavier Lambin 《Journal of avian biology》2018,49(1)
The period prior to an individual emigrating from its natal site and initiating dispersal is important for developing the skills that are ultimately required for surviving natal dispersal. Using a novel method to quantify the early movements of 35 juvenile golden eagles fitted with satellite transmitters, we hypothesised that variation in golden eagles’ post‐fledging dependence period (PFDP) was determined by variation in how quickly movement skills were acquired in order to become independent and disperse. Twenty nine young eagles exhibited an initial increase in mobility (‘ontogenic phase’) levelling off after a median of 68 d, followed by a period of maintained mobility (‘maintained phase’) that lasted a median of 99 d (range 24–176). Eagles that developed their mobility more quickly during the ontogenic phase had a correspondingly shorter ontogenic phase. Despite this, most of the inter‐individual variation in the length of the PFDP resulted from variation in the length of the ‘maintained phase’. In general, females (the larger sex) developed more slowly and had a longer ontogenic phase. Males exhibited dispersal strategies around two modes with some dispersing early (mode 1: 89.5 d) and others late (mode 2: 220 d). In contrast females dispersed around a unimodal distribution of timing (mode 167.5 d). Apart from six individuals (mostly males) which dispersed with no discernible maintained phase, most offspring remained in the parental home range after they were fully mobile, even those that developed mobility quickly, suggesting that the PFDP in golden eagles is not simply a function of physical capacity for independence, but also a period when young eagles decide to remain, and are tolerated by parents, in their parental home range before dispersing. We suggest that delaying dispersal may be a beneficial strategy for young raptors facing a competitive environment after PFDP. 相似文献
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Lucas R Lopes Vitor AR Miranda Rodrigo A Goes Gabriel GA Souza Giuliana R Souza Jessica CS Rocha Victor RA Cossich Jamila A Perini 《Biology of sport / Institute of Sport》2021,38(4):703
The COVID-19 pandemic has presented significant challenges and implications for the sports community. Thus, this study aimed to describe the prevalence of COVID-19 in Brazilian athletes and identify the epidemiological, clinical, athletic, life and health factors associated with the disease in these individuals. A cross-sectional study was performed involving 414 athletes from 22 different sports using an online questionnaire from August to November 2020. The association between the athletes’ characteristics and COVID-19 was evaluated using a logistic regression model. The prevalence of COVID-19 was 8.5%, although only 40% of athletes reported having been tested. Being under 27 years of age (3-fold), having children (~5-fold), having a teammate test positive for COVID-19 (2.5-fold), and smoking (14-fold) were associated with a possible higher risk of disease. Almost 20% of athletes self-reported musculoskeletal injuries during the period of the pandemic that was studied. Athletes with a university education (P = 0.02), a profession other than sports (P < 0.001), those from a low-income family (P = 0.01), and public health system users (P = 0.04) were significantly less frequently tested for COVID-19, whereas international competitors, athletes who received a wage, and athletes who had a teammate who tested positive for COVID-19 were 2-, 3-, and 15-fold more likely to be tested for COVID-19, respectively. Approximately 26% of the athletes who tested negative or were untested reported more than three characteristic COVID-19 symptoms, and 11% of athletes who tested positive for COVID-19 were asymptomatic. The identification of modifiable (have children, smoking, and teammates positively tested) and non-modifiable (age under 27 years) factors related to COVID-19 in athletes can contribute to implementing surveillance programmes to decrease the incidence of COVID-19 in athletes and its negative impacts in sports. 相似文献
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Tyler J. Clark Anne‐Sophie Bonnet‐Lebrun Letizia Campioni Paulo Catry Ewan Wakefield 《Ibis》2019,161(1):192-197
The Sooty Shearwater Ardenna grisea, an abundant but declining petrel, is one of many seabird species that construct breeding burrows, presumably because these confer protection from predators and the elements. Little is known about the causes of variation in Sooty Shearwater burrow architecture, which can differ markedly both within and between breeding sites. We hypothesize that burrow architecture varies in response to habitat type and competition for space. To address these hypotheses, we recorded Sooty Shearwater burrow dimensions on Kidney Island, the largest Sooty Shearwater colony in the Falkland Islands, South Atlantic, and modelled these as functions of burrow density (a proxy for competition) and habitat indices. Our models suggest that Sooty Shearwaters burrow further underground in response to competition for breeding space, and that soil underlying dense tussac grass Poa flabellata is more easily excavated than other substrates, indicating how vegetation restoration could aid the conservation of this species. 相似文献