全文获取类型
收费全文 | 1733篇 |
免费 | 129篇 |
国内免费 | 1篇 |
出版年
2023年 | 18篇 |
2022年 | 37篇 |
2021年 | 85篇 |
2020年 | 34篇 |
2019年 | 57篇 |
2018年 | 47篇 |
2017年 | 54篇 |
2016年 | 68篇 |
2015年 | 107篇 |
2014年 | 106篇 |
2013年 | 130篇 |
2012年 | 157篇 |
2011年 | 150篇 |
2010年 | 96篇 |
2009年 | 96篇 |
2008年 | 112篇 |
2007年 | 101篇 |
2006年 | 84篇 |
2005年 | 74篇 |
2004年 | 55篇 |
2003年 | 55篇 |
2002年 | 40篇 |
2001年 | 13篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有1863条查询结果,搜索用时 31 毫秒
991.
Ashira Lubkin Warren L. Lee Francis Alonzo Changsen Wang Jason Aligo Matthew Keller Natasha M. Girgis Tamara Reyes-Robles Rita Chan Aidan O’Malley Peter Buckley Nikollaq Vozhilla Marilyn T. Vasquez Johnny Su Michael Sugiyama Stephen T. Yeung Maryaline Coffre Sofia Bajwa Victor J. Torres 《Cell host & microbe》2019,25(3):463-470.e9
992.
Joedison Rocha Rudi Ricardo Laps Caio Graco Machado Sofia Campiolo 《Ecology and evolution》2019,9(14):7903-7913
Cacao agroforestry have been considered as biodiversity‐friendly farming practices by maintaining habitats for a high diversity of species in tropical landscapes. However, little information is available to evaluate whether this agrosystem can maintain functional diversity, given that agricultural changes can affect the functional components, but not the taxonomic one (e.g., species richness). Thus, considering functional traits improve the understanding of the agricultural impacts on biodiversity. Here, we measured functional diversity (functional richness‐FD, functional evenness‐FEve, and functional divergence‐Rao) and taxonomic diversity (species richness and Simpson index) to evaluate changes of bird diversity in cacao agroforestry in comparison with nearby mature forests (old‐growth forests) in the Brazilian Atlantic Forest. We used data from two landscapes with constraining areas of mature forest (49% Una and 4.8% Ilhéus) and cacao agroforestry cover (6% and 82%, respectively). To remove any bias of species richness and to evaluate assembly processes (functional overdispersion or clustering), all functional indices were adjusted using null models. Our analyses considered the entire community, as well as separately for forest specialists, habitat generalists, and birds that contribute to seed dispersal (frugivores/granivores) or invertebrate removal (insectivores). Our findings showed that small cacao agroforestry in the forested landscape sustains functional diversity (FD and FEve) as diverse as nearby forests when considering the entire community, forest specialist, and habitat generalists. However, we observed declines for frugivores/granivores and insectivores (FD and Rao). These responses of bird communities differed from those observed by taxonomic diversity, suggesting that even species‐rich communities in agroforestry may capture lower functional diversity. Furthermore, communities in both landscapes showed either functional clustering or neutral processes as the main driver of functional assembly. Functional clustering may indicate that local conditions and resources were changed or lost, while neutral assemblies may reveal high functional redundancy at the landscape scale. In Ilhéus, the neutral assembly predominance suggests an effect of functional homogenization between habitats. Thus, the conservation value of cacao agroforestry to harbor species‐rich communities and ecosystem functions relies on smallholder production with reduced farm management in a forested landscape. Finally, we emphasize that seed dispersers and insectivores should be the priority conservation targets in cacao systems. 相似文献
993.
Cyst‐theca relationships and phylogenetic positions of Peridiniales (Dinophyceae) with two anterior intercalary plates,with description of Archaeperidinium bailongense sp. nov. and Protoperidinium fuzhouense sp. nov
下载免费PDF全文
![点击此处可从《Phycological Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
994.
Patrick L. Collins Marina Cella Sofia I. Porter Shasha Li Greer L. Gurewitz Henoch S. Hong R. Paul Johnson Eugene M. Oltz Marco Colonna 《Cell》2019,176(1-2):348-360.e12
995.
Peter van Galen Volker Hovestadt Marc H. Wadsworth II Travis K. Hughes Gabriel K. Griffin Sofia Battaglia Julia A. Verga Jason Stephansky Timothy J. Pastika Jennifer Lombardi Story Geraldine S. Pinkus Olga Pozdnyakova Ilene Galinsky Richard M. Stone Timothy A. Graubert Alex K. Shalek Jon C. Aster Andrew A. Lane Bradley E. Bernstein 《Cell》2019,176(6):1265-1281.e24
996.
Beln Corallo Sofia Simeto Gonzalo Martínez Demian Gmez Eduardo Abreo Nora Altier Sandra Lupo 《Journal of Applied Entomology》2019,143(5):542-555
Thaumastocoris peregrinus Carpintero & Dellapé (Heteroptera: Thaumastocoridae) is a sap‐sucking insect that feeds on leaves of Eucalyptus. In Uruguay, it was detected in 2008 causing significant economic losses in Eucalyptus plantations. At present, there is no efficient control for this pest; thus, the use of biological control agents seems to be an environmentally friendly alternative to reduce the damage caused by this insect. The aims of this study were to isolate and identify the species of entomopathogenic fungi that naturally infect T. peregrinus in Uruguay and to characterize and select the most virulent isolates towards this pest. Individuals of T. peregrinus were collected in eight Eucalyptus plantations infested by the pest. The entomopathogenic fungi were isolated and identified by observation of their micromorphological characteristics, and their identity was confirmed by molecular methods. The pathogenicity and virulence against T. peregrinus of the isolated entomopathogenic fungi were evaluated. Isolates causing the highest insect mortality were selected to evaluate the effect of temperature and water activity on conidial viability. Entomopathogenic fungi were found in very low number with the prevalence of less than 3%. Isolates corresponded to Beauveria, Fusarium, Isaria, Lecanicillium, Paecilomyces, Pochonia, Purpureocillium and Simplicillium genera. Two species, B. pseudobassiana and L. muscarium, were first recorded in Uruguay. Among all the tested species, an isolate of B. bassiana (FI 2403) showed the highest virulence followed by an isolate of B. pseudobassiana. The isolate of B. bassiana presented the highest percentage of spore germination at the three temperatures and the highest viability at low water activities. Isolate FI 2403 was selected as a promissory candidate for the development of a commercial formulation against T. peregrinus. 相似文献
997.
998.
Miniadis-Meimaroglou S Dimizas C Loukas V Moukas A Vlachos A Thomaidis N Paraskevopoulou V Dasenakis M 《Chemistry and physics of lipids》2007,146(2):104-110
The proximate composition of frozen red porgy (Pagrus pagrus) was determined. The moisture, ash, protein and total lipids (45.5+/-1.4% PL of which 90.4+/-2.0% PhL) were found to be 71.7+/-1.0%, 1.73+/-0.12%, 21.5+/-0.8% and 0.81+/-0.09% of the wet muscle tissue, respectively. 16:0 and 18:0 were the main SFA, 18:1 (omega-9 and omega-7) the main MUFA while DHA, EPA and arachidonic acid were the main polyunsaturated fatty acids (PUFA). The SFA/PUFA ratio was 1.5 and the omega-3/omega-6 ratio was 3.02. The cholesterol content was found to be 8.18+/-0.34 mg/100 g of the wet muscle tissue. Ni, Cr, Mn, Cu, Zn, Fe and Mg were determined in the muscles, skin, hepatopancreas and head of the fish. The covering percentage of the recommended daily allowance/intake (RDA/RDI) for each mineral, in the muscle tissue, has been calculated to 14.2% (males) and 7.89% (females) for Fe, 2.87% for Cu, 4.07% for Zn 0.4% for Mn, 13.9% for Ni, 20.2% for Cr and 10.4% for Mg. 相似文献
999.
1000.
Selvatici R Falzarano S Franceschetti L Spisani S Siniscalchi A 《Archives of biochemistry and biophysics》2007,462(1):74-82
PKI55 protein, coded by the recently identified KI55 gene [R. Selvatici, E. Melloni, M. Ferrati, C. Piubello, F.C. Marincola, E. Gandini, J. Mol. Evol. 57 (2003) 131-139] is synthesized following protein kinase C (PKC) activation and acts as a PKC modulator, establishing a feedback loop of inhibition. In this work, PKI55 was found to inhibit recombinant alpha, beta(1), beta(2), gamma, delta, zeta and eta PKC isoforms; the effect on conventional PKC was lost in the absence of calcium. Confocal immunofluorescence experiments showed that PKI55 can penetrate into peripheral blood mononuclear cells (PBMC), following a coordinated movement of calcium ions. The addition of PKI55 protein down-regulated the PKC enzyme activity in phytohaemagglutinin-activated PBMC, decreasing the activity of alpha, beta(1) and beta(2) PKC isoforms. Moreover, inhibition in PBMC proliferation was observed. Similar effects were detected in Jurkat T cells transfected with a plasmid containing the coding sequence of PKI55. The PKI55 protein functional role could be to control the pathological over-expression of specific PKC isoforms and to regulate proliferation. 相似文献