全文获取类型
收费全文 | 478篇 |
免费 | 25篇 |
专业分类
503篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 15篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 23篇 |
2016年 | 18篇 |
2015年 | 31篇 |
2014年 | 26篇 |
2013年 | 34篇 |
2012年 | 52篇 |
2011年 | 42篇 |
2010年 | 25篇 |
2009年 | 19篇 |
2008年 | 34篇 |
2007年 | 17篇 |
2006年 | 20篇 |
2005年 | 13篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有503条查询结果,搜索用时 13 毫秒
31.
Martínková N Bačkor P Bartonička T Blažková P Cervený J Falteisek L Gaisler J Hanzal V Horáček D Hubálek Z Jahelková H Kolařík M Korytár L Kubátová A Lehotská B Lehotský R Lučan RK Májek O Matějů J Rehák Z Šafář J Tájek P Tkadlec E Uhrin M Wagner J Weinfurtová D Zima J Zukal J Horáček I 《PloS one》2010,5(11):e13853
Background
White-nose syndrome is a disease of hibernating insectivorous bats associated with the fungus Geomyces destructans. It first appeared in North America in 2006, where over a million bats died since then. In Europe, G. destructans was first identified in France in 2009. Its distribution, infection dynamics, and effects on hibernating bats in Europe are largely unknown.Methodology/Principal Findings
We screened hibernacula in the Czech Republic and Slovakia for the presence of the fungus during the winter seasons of 2008/2009 and 2009/2010. In winter 2009/2010, we found infected bats in 76 out of 98 surveyed sites, in which the majority had been previously negative. A photographic record of over 6000 hibernating bats, taken since 1994, revealed bats with fungal growths since 1995; however, the incidence of such bats increased in Myotis myotis from 2% in 2007 to 14% by 2010. Microscopic, cultivation and molecular genetic evaluations confirmed the identity of the recently sampled fungus as G. destructans, and demonstrated its continuous distribution in the studied area. At the end of the hibernation season we recorded pathologic changes in the skin of the affected bats, from which the fungus was isolated. We registered no mass mortality caused by the fungus, and the recorded population decline in the last two years of the most affected species, M. myotis, is within the population trend prediction interval.Conclusions/Significance
G. destructans was found to be widespread in the Czech Republic and Slovakia, with an epizootic incidence in bats during the most recent years. Further development of the situation urgently requires a detailed pan-European monitoring scheme. 相似文献32.
G Gashi V Mahovlić E Bahtiri F Kurshumliu A Podrimaj-Bytyqi IR Elezaj 《Biotechnic & histochemistry》2013,88(7):496-504
Human papilloma virus (HPV) infection is the main etiological factor for cervical intraepithelial lesions (CIN). An important characteristic of this process is the loss of genome stability. Therefore, it is imperative to use biomarkers of DNA damage caused by genomic instability to identify high risk individuals. We investigated the frequency of micronuclei (MN) in peripheral blood lymphocytes (PBL) of 20 patients, diagnosed as histologically CIN 1 and 10 healthy controls. We also examined the frequency of other nuclear anomalies including nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) in PBL of patients with CIN 1 and healthy controls, and evaluated the benefits of p16INK4a and Ki-67 (p16INK4a/Ki-67) immunohistochemical double staining for identifying cervical squamous cells that express HPV E6/E7 oncogenes. We analyzed the association between the frequency of MN in PBL and the amount of p16INK4a/Ki-67 co-expression in CIN 1 patients to establish genomic instability. Among CIN 1 subjects, 15% exhibited diffuse p16INK4a/Ki-67 co-expression and were considered high positive, 25% of the CIN 1 cases exhibited p16INK4a/Ki-67 co-expression restricted to the lower part of the epithelium and were considered low positive and the remaining 60% of cases were negative. The frequency of MN, NPBs and NBUDs differed significantly among groups. We found a statistically significant positive correlation between p16INK4a/Ki-67 co-expression and the frequency of MN, NPBs and NBUDs in PBL. Our findings demonstrate the efficacy of p16INK4a/Ki-67 double immunostaining for histological samples with CIN 1. MN frequency in PBL might be useful for detecting genomic instability in cases of HPV infection and CIN. 相似文献
33.
Natália Carolina de Almeida Silva Rafael Vidal Flaviane Malaquias Costa Magdalena Vaio Juliana Bernardi Ogliari 《PloS one》2015,10(10)
Records of the occurrence of wild relatives of maize in South American lowlands are unprecedented, especially in sympatric coexistence with landraces. This fact is relevant, because regions of occurrence of wild relatives of cultivated plants should be a priority for conservation, even if they do not correspond to the center of origin of the species. The aim of this study was to identify and characterize the wild relatives of maize in the Far West of Santa Catarina, southern Brazil. Therefore, phenotypic characterization was performed for five populations, based on 22 morphological traits deemed as fundamental for classifying the species of the genus Zea, and validated through the characterization of chromosomal knobs of two populations. The occurrence and distribution of teosinte populations were described through semi-structured interviews applied to a sample of 305 farmers. A total of 136 teosinte populations were identified; 75% of them occur spontaneously, 17% are cultivated populations, and 8% occur both ways, for the same farm. Populations that were characterized morphologically had trapezoidal fruits mostly, upright tassel branch (4–18), non-prominent main branch and glabrous glumes, with two protruding outer ribs and 8 inner ribs, on average. Cytogenetic analysis identified 10 pairs of homologous chromosomes (2n = 20) with 26 knobs, located in the terminal region of all chromosomes. The similarity of these results with the information reported in the literature indicates that the five populations of wild relatives of maize in this region of Santa Catarina belong to the botanical species Zea luxurians. 相似文献
34.
Abdulahi Alfonso-Morales Liliam Rios Orlando Martínez-Pérez Roser Dolz Rosa Valle Carmen L. Perera Kateri Bertran Maria T. Frías Llilianne Ganges Heidy Díaz de Arce Natàlia Majó José I. Nú?ez Lester J. Pérez 《PloS one》2015,10(5)
BackgroundInfectious bursal disease (IBD) is a highly contagious and acute viral disease, which has caused high mortality rates in birds and considerable economic losses in different parts of the world for more than two decades and it still represents a considerable threat to poultry. The current study was designed to rigorously measure the reliability of a phylogenetic marker included into segment B. This marker can facilitate molecular epidemiology studies, incorporating this segment of the viral genome, to better explain the links between emergence, spreading and maintenance of the very virulent IBD virus (vvIBDV) strains worldwide.Conclusions/SignificanceThis study contributes to a better understanding of the emergence of vvIBDV strains, describing molecular epidemiology of IBDV using the state-of-the-art methodology concerning phylogenetic reconstruction. This study also revealed the presence of a novel natural reassorted strain as possible manifest of change in the genetic structure and stability of the vvIBDV strains. Therefore, it highlights the need to obtain information about both genome segments of IBDV for molecular epidemiology studies. 相似文献
35.
Mariana Malzoni Furtado Solange Maria Gennari Cassia Yumi Ikuta Anah Tereza de Almeida Jácomo Zenaide Maria de Morais Hilda Fátima de Jesus Pena Grasiela Edith de Oliveira Porfírio Leandro Silveira Rahel Sollmann Gisele Oliveira de Souza Natália Mundim T?rres José Soares Ferreira Neto 《PloS one》2015,10(11)
This study investigated the exposure of jaguar populations and domestic animals to smooth Brucella, Leptospira spp. and Toxoplasma gondii in the Cerrado, Pantanal and Amazon biomes of Brazil. Between February 2000 and January 2010, serum samples from 31 jaguars (Panthera onca), 1,245 cattle (Bos taurus), 168 domestic dogs (Canis lupus familiaris) and 29 domestic cats (Felis catus) were collected and analysed by rose bengal test for smooth Brucella, microscopic agglutination test for Leptospira spp. and modified agglutination test for T. gondii. Cattle populations from all sites (9.88%) were exposed to smooth Brucella, but only one jaguar from Cerrado was exposed to this agent. Jaguars captured in the Cerrado (60.0%) and in the Pantanal (45.5%) were seropositive for different serovars of Leptospira spp., cattle (72.18%) and domestic dogs (13.1%) from the three sites and one domestic cat from Pantanal were also seropositive for the agent. The most prevalent serotype of Leptospira spp. identified in jaguars from the Cerrado (Grippotyphosa) and the Pantanal (Pomona) biomes were distinct from those found in the domestic animals sampled. Jaguars (100%), domestic dogs (38.28%) and domestic cats (82.76%) from the three areas were exposed to T. gondii. Our results show that brucellosis and leptospirosis could have been transmitted to jaguars by domestic animals; and jaguars probably play an important role in the maintenance of T. gondii in nature. 相似文献
36.
Gabriel Costa Serr?o de Araújo Natália Teixeira Mour?o Igor Natário Pinheiro Analúcia Rampazzo Xavier Vinicius Schott Gameiro 《PloS one》2015,10(10)
Background
Gunshot wounds require surgeons to decide whether to remove or leave bullet fragments in the body. Surgeons also decide how to follow up with patients who have lead fragments retained in their body. Current literature recommends to remove only intra-articular fragments without the need for a follow-up for patients with the metal retained. Therefore, this study investigates chronic lead toxicity for gunshot wounds.Methods
The study was performed in the metropolitan area of Rio de Janeiro/Brazil, between 2013 and 2015. It was a case-control study that included 45 victims of gunshot lesions with metallic fragments retained for more than 6 months. The 45 controls were matched for gender, age, and race. We compared the lead blood levels and frequency of symptoms.Results
The control group had average blood lead levels of 2.17 μg/dL (95% Confidence Interval [CI]; 1.71–2.63) and median 2.1 μg/dL. The case group had average values of 9.01 μg/dL (CI; 6.07–11.96) and median values of 6.5 μg/dL with p-values < = 0.001. The case group reported the following more frequently: irritancy, bad mood, headache, memory losses, daylight drowsiness, myalgia, weakness, abdominal pain, joint pain, trembling, tingling limbs. There was statistical significance for the differences of symptoms frequencies and for odds ratio between groups.Conclusions
Although the mean lead levels found were lower than the current laboratory references, low levels have been associated with both rising morbidity and mortality. The WHO stated: “There is no known level of lead exposure that is considered safe”. In conclusion, this work showed that bullets retained in the body are not innocuous. There are impacts in the blood lead levels and symptoms related to it, even with few fragments, extra-articular located or existing with low blood lead levels. 相似文献37.
Bánóczi Z Gorka-Kereskényi Á Reményi J Orbán E Hazai L Tökési N Oláh J Ovádi J Béni Z Háda V Szántay C Hudecz F Kalaus G Szántay C 《Bioconjugate chemistry》2010,21(11):1948-1955
Vinblastine is a widely used anticancer drug with undesired side effects. Its conjugation with carrier molecules could be an efficient strategy to reduce these side effects. Besides this, the conjugate could exhibit increased efficiency against resistant cells, e.g., due to the altered internalization pathway. Oligoarginines, as cell-penetrating peptides, can transport covalently attached compounds into different kinds of cells and enhance the efficiency of those compounds. We report here the coupling of vinblastine through its carboxyl group at position 16 with the N-terminal amino function of L-Trp methyl ester. After hydrolysis of the ester group, 17-desacetylvinblastineTrp was conjugated to the N-terminal amino group of oligoarginine via the C-terminal carboxyl group of the Trp moiety in solution. The antitumor effect of conjugates was studied on sensitive and resistant human leukemia (HL-60) cells in vitro. Our data suggest that all conjugates investigated possess an antiproliferative effect against the studied cells. However, the effect was dependent on the number of Arg residues in the conjugates: Arg? > Arg? ? Arg?. The conjugate with Arg? exhibited similar efficicacy as compared with free 17-desacetylvinblastineTrp. The in vitro studies also showed that the tubulin binding ability of vinblastine was essentially preserved even in the octaarginine conjugate. We also observed that two isomers were formed during conjugation. These isomers showed different levels of activity against tubulin polymerization in vitro and in vivo. The 17-desacetylvinblastineTrp-Arg?-1 isomer conjugate possessed high selectivity against the mitotic spindles. HRMS and NMR data suggest that 17-desacetylvinblastineTrp-Arg?-1 and 17-desacetylvinblastineTrp-Arg?-2 are epimers at the tryptophan α carbon atom. 相似文献
38.
Malaria is still a major public health problem in Brazil, with approximately 306 000 registered cases in 2009, but it is estimated that in the early 1940s, around six million cases of malaria occurred each year. As a result of the fight against the disease, the number of malaria cases decreased over the years and the smallest numbers of cases to-date were recorded in the 1960s. From the mid-1960s onwards, Brazil underwent a rapid and disorganized settlement process in the Amazon and this migratory movement led to a progressive increase in the number of reported cases. Although the main mosquito vector (Anopheles darlingi) is present in about 80% of the country, currently the incidence of malaria in Brazil is almost exclusively (99,8% of the cases) restricted to the region of the Amazon Basin, where a number of combined factors favors disease transmission and impair the use of standard control procedures. Plasmodium vivax accounts for 83,7% of registered cases, while Plasmodium falciparum is responsible for 16,3% and Plasmodium malariae is seldom observed. Although vivax malaria is thought to cause little mortality, compared to falciparum malaria, it accounts for much of the morbidity and for huge burdens on the prosperity of endemic communities. However, in the last few years a pattern of unusual clinical complications with fatal cases associated with P. vivax have been reported in Brazil and this is a matter of concern for Brazilian malariologists. In addition, the emergence of P. vivax strains resistant to chloroquine in some reports needs to be further investigated. In contrast, asymptomatic infection by P. falciparum and P. vivax has been detected in epidemiological studies in the states of Rondonia and Amazonas, indicating probably a pattern of clinical immunity in both autochthonous and migrant populations. Seropidemiological studies investigating the type of immune responses elicited in naturally-exposed populations to several malaria vaccine candidates in Brazilian populations have also been providing important information on whether immune responses specific to these antigens are generated in natural infections and their immunogenic potential as vaccine candidates. The present difficulties in reducing economic and social risk factors that determine the incidence of malaria in the Amazon Region render impracticable its elimination in the region. As a result, a malaria-integrated control effort - as a joint action on the part of the government and the population - directed towards the elimination or reduction of the risks of death or illness, is the direction adopted by the Brazilian government in the fight against the disease. 相似文献
39.
40.
Zanin Fabiana Couto Freitas Natália Chagas Pinto Renan Terassi Máximo Wesley Pires Flausino Diniz Leandro Eugenio Cardamone Paiva Luciano Vilela 《Molecular biology reports》2022,49(3):1973-1984
Molecular Biology Reports - Small auxin-up RNA (SAUR) genes form a wide family supposedly involved in different physiological and developmental processes in plants such as leaf senescence, auxin... 相似文献