全文获取类型
收费全文 | 1149篇 |
免费 | 65篇 |
出版年
2024年 | 2篇 |
2023年 | 12篇 |
2022年 | 29篇 |
2021年 | 53篇 |
2020年 | 31篇 |
2019年 | 37篇 |
2018年 | 47篇 |
2017年 | 44篇 |
2016年 | 56篇 |
2015年 | 83篇 |
2014年 | 82篇 |
2013年 | 98篇 |
2012年 | 87篇 |
2011年 | 76篇 |
2010年 | 38篇 |
2009年 | 47篇 |
2008年 | 44篇 |
2007年 | 56篇 |
2006年 | 53篇 |
2005年 | 45篇 |
2004年 | 27篇 |
2003年 | 32篇 |
2002年 | 24篇 |
2001年 | 23篇 |
2000年 | 6篇 |
1999年 | 13篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1965年 | 1篇 |
1941年 | 1篇 |
1940年 | 1篇 |
1903年 | 1篇 |
排序方式: 共有1214条查询结果,搜索用时 15 毫秒
991.
992.
Binu M. Tripathi David P. Edwards Lucas William Mendes Mincheol Kim Ke Dong Hyoki Kim Jonathan M. Adams 《Molecular ecology》2016,25(10):2244-2257
Selective logging and forest conversion to oil palm agriculture are rapidly altering tropical forests. However, functional responses of the soil microbiome to these land‐use changes are poorly understood. Using 16S rRNA gene and shotgun metagenomic sequencing, we compared composition and functional attributes of soil biota between unlogged, once‐logged and twice‐logged rainforest, and areas converted to oil palm plantations in Sabah, Borneo. Although there was no significant effect of logging history, we found a significant difference between the taxonomic and functional composition of both primary and logged forests and oil palm. Oil palm had greater abundances of genes associated with DNA, RNA, protein metabolism and other core metabolic functions, but conversely, lower abundance of genes associated with secondary metabolism and cell–cell interactions, indicating less importance of antagonism or mutualism in the more oligotrophic oil palm environment. Overall, these results show a striking difference in taxonomic composition and functional gene diversity of soil microorganisms between oil palm and forest, but no significant difference between primary forest and forest areas with differing logging history. This reinforces the view that logged forest retains most features and functions of the original soil community. However, networks based on strong correlations between taxonomy and functions showed that network complexity is unexpectedly increased due to both logging and oil palm agriculture, which suggests a pervasive effect of both land‐use changes on the interaction of soil microbes. 相似文献
993.
Ana M. Martín González Bo Dalsgaard David Nogués‐Bravo Catherine H. Graham Matthias Schleuning Pietro K. Maruyama Stefan Abrahamczyk Ruben Alarcón Andréa C. Araujo Francielle P. Araújo Severino Mendes de Azevedo Jr Andrea C. Baquero Peter A. Cotton Tanja Toftemark Ingversen Glauco Kohler Carlos Lara Flor Maria Guedes Las‐Casas Adriana O. Machado Caio Graco Machado María Alejandra Maglianesi Jimmy A. McGuire Alan Cerqueira Moura Genilda M. Oliveira Paulo E. Oliveira Juan Francisco Ornelas Licléia da Cruz Rodrigues Liliana Rosero‐Lasprilla Ana M. Rui Marlies Sazima Allan Timmermann Isabela Galarda Varassin Jeferson Vizentin‐Bugoni Zhiheng Wang Stella Watts Carsten Rahbek Neo D. Martinez 《Global Ecology and Biogeography》2015,24(11):1212-1224
994.
Dolichoura has two species, D. spiritusanctensis and D. kollmannii, the latter described here. The genus can be recognized within the tribe Merianieae by 6-or 7-merous flowers, purple petals,
stamens with a dorsal, spiraled appendage at the base of the connective, and seeds with narrow, lateral wings. The new species
can be recognized by the suffruticose habit, 4-winged branches, coriaceous leaves with very small petioles and bullate adaxial
surfaces, and by the 6-merous flowers. 相似文献
995.
da Silva VL Diniz CG dos Santos SG Gomes RM Nicoli JR Magalhães PP Mendes EN de Carvalho MA Farias LM 《Journal of applied microbiology》2007,103(1):20-26
AIM: The purpose of this study was to investigate the effect of oxidative stress on physiological and genetic characteristics of Fusobacterium nucleatum and its interference on this microbial identification methods. METHODS AND RESULTS: Fus. nucleatum ssp. nucleatum ATCC 25586 (wt-strain) and an oxidative-stress-adapted strain derived from the wt-strain (aero-strain) were employed in the study. Cell-free crude protein extracts were obtained from both strains and differentially expressed proteins were identified by two-dimensional electrophoresis. Bacterium identification was performed by conventional biochemical tests, automated Rapid ID 32A system and specific PCR analysis. Genetic diversity between wt- and aero-strain was assessed by arbitrarily-primed (AP)-PCR. There were significant changes in the protein profile of aero-strain. The identification of the wt-strain was confirmed by all methods employed. Similar results were obtained for aero-strain when conventional biochemical tests and PCR were used. However, aero-strain was identified as Fusobacterium varium when submitted to Rapid ID 32A system. According to AP-PCR analysis, no significant genetic alteration was detected in aero-strain. CONCLUSIONS: The adaptive response of Fus. nucleatum to oxidative stress is associated with changes on its biology, which may lead to misidentification of the organism, according to the conventional identification methods. SIGNIFICANCE AND IMPACT OF THE STUDY: Oxidative stress may act as a cause of adaptive response in Fus. nucleatum with consequences to its biology, such as alterations on biochemical and physiological profile. 相似文献
996.
Molecular typing and antifungal susceptibility of clinical sequential isolates of Cryptococcus neoformans from Sao Paulo State, Brazil 总被引:1,自引:0,他引:1
Almeida AM Matsumoto MT Baeza LC de Oliveira E Silva RB Kleiner AA Melhem Mde S Mendes Giannini MJ;Laboratory Group on Cryptococcosis 《FEMS yeast research》2007,7(1):152-164
The antifungal susceptibility profiles and the genetic variability of 83 sequential clinical isolates of Cryptococcus neoformans, including four Cryptococcus gattii isolates, obtained from 38 Sao Paulo AIDS patients with cryptococcal meningitis were assessed by electrophoretic karyotyping and random amplified polymorphic DNA (RAPD) analysis. The majority of the Cryptococcus neoformans isolates were highly susceptible to amphotericin B and fluconazole. Twenty percent of the minimum inhibitory concentration values for amphotericin B varied from 0.5 to 1 micro g mL(-1). For fluconazole, 22% occurred in the range 8-16 mug mL(-1). Sequential isolates from nine patients showed a trend towards lower susceptibility to fluconazole, flucytosine, itraconazole and amphotericin B. The results of molecular typing by electrophoretic karyotyping and RAPD analysis showed the presence of 22 electrophoretic karyotypes (EK) and 15 RAPD profiles that were highly correlated. Our results provided evidence for the occurrence of genetic changes in some strains associated with microevolution during the course of infection. We also observed both microevolution and simultaneous coinfection with two distinct Cryptococcus neoformans strains in one patient. In some patients, we found changed EK- and RAPD patterns in association with increased MIC values. 相似文献
997.
da Silva CA Coimbra JS Rojas EE Minim LA da Silva LH 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,858(1-2):205-210
This study evaluates the influence of type of salt and temperature on the partition coefficient of caseinomacropetide (CMP) to determine the best conditions for the recovery of CMP in aqueous two-phase systems (ATPS) composed by poly(ethylene glycol) (PEG) 1500 and an inorganic salt (potassium phosphate, sodium citrate, lithium sulfate or sodium sulfate). In all systems, CMP presented affinity for the PEG-rich phase. The PEG1500+lithium sulfate showed the highest values of partitioning coefficient. In addition, thermodynamic parameters (DeltaH degrees , DeltaS degrees , DeltaG degrees) as a function of temperature, were calculated for the system PEG1500-sodium citrate at different PEG concentrations and the results imply thermodynamic differences between partitioning of CMP in this system. 相似文献
998.
We performed cytogenetic analyses on specimens from three population samples of Proceratophrys boiei from southeastern and northeastern Brazil. We stained chromosomes of mitotic and meiotic cells with Giemsa, C-banding and Ag-NOR methods. All specimens of P. boiei presented a karyotype with a full chromosome complement of 2n=22, metacentric and submetacentric. We observed the secondary constriction within the short arm of pair 8, which was in the same position of the nucleolus organizer region (NOR). NOR heteromorphism was observed within two specimens from the municipality of Mata de S?o Jo?o (northeastern Bahia State). The C-banding evidenced an unusual heterochromatic pattern in the genome of P. boiei. In the southern most population samples (S?o Paulo State), we observed large blocks of heterochromatin in the centromeric regions of all chromosomes, whereas the northernmost samples (Bahia State) presented a small amount of constitutive heterochromatin. We suppose that this geographic variation in heterochromatin quantities could be due to heterochromatinization of some chromosome regions in the genome of the S?o Paulo samples. Furthermore, females from S?o Paulo presented, within chromosome pair 1 from C-banded karyotypes, one homologous chromosome almost heterochromatic, whereas males had heterochromatin restricted to the centromeric region. This unusual heterochromatic arrangement led us to assume that P. boiei owns a ZZ/ZW type of sexual determination system. This finding is very important, as this is the first record of ZZ/ZW sex chromosomes within Cycloramphidae. We believe that the cytogenetic differences found between southeastern and northeastern Brazilian population samples of P. boiei strongly supports the existence of a species complex under the name P. boiei, and the requirement of taxonomic and systematic reviews by morphological, bioacoustical, molecular, and cytogenetic data could define this taxonomic issue in the future. 相似文献
999.
Freire Filho Robrio Inforzato Igor Tabacow Fernanda P. Martins Waldney Possamai Carla B. Ferraz Daniel Hack Robson O. E. Rocha Samantha Slomp Daniel V. Nery Marcello S. Almeida Letcia Fernandes Nala Alves Pedro Paulo Rezende Mendes Srgio L. Strier Karen B. 《Primates; journal of primatology》2022,63(4):335-342
Primates - Primate thanatology, or the study of primate responses to dying and death, has become increasingly relevant in recent years. However, the number of reports remains small and the quality... 相似文献
1000.
Oliveira Samara Rodrigues Bonfim Damasceno Franco Álvaro Xavier Quaresma Marielle Pires de Carvalho Cecília Mendes Morais da Cunha Jácome Marques Fabrícia da Silva Pantoja Patrícia Mendonça Vanessa Azevedo da Silva Osterne Vinicius José Correia Jorge Luis Almeida Assreuy Ana Maria Sampaio de Souza Marcellus Henrique Loiola Pontes do Nascimento Kyria Santiago Cavada Benildo Sousa Criddle David Neil Soares Pedro Marcos Gomes 《Glycoconjugate journal》2022,39(5):599-608
Glycoconjugate Journal - Lectins isolated from Canavalia ensiformis (ConA) and Canavalia brasiliensis (ConBr) are promising molecules to prevent cell death. Acute pancreatitis, characterized by... 相似文献