全文获取类型
收费全文 | 616篇 |
免费 | 54篇 |
国内免费 | 3篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 6篇 |
2018年 | 19篇 |
2017年 | 9篇 |
2016年 | 24篇 |
2015年 | 22篇 |
2014年 | 20篇 |
2013年 | 40篇 |
2012年 | 42篇 |
2011年 | 40篇 |
2010年 | 40篇 |
2009年 | 34篇 |
2008年 | 38篇 |
2007年 | 33篇 |
2006年 | 32篇 |
2005年 | 20篇 |
2004年 | 17篇 |
2003年 | 20篇 |
2002年 | 15篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 4篇 |
1970年 | 2篇 |
1940年 | 2篇 |
排序方式: 共有673条查询结果,搜索用时 78 毫秒
21.
German Andres Estrada Vera Lúcia Divan Baldani Danilo Messias de Oliveira Segundo Urquiaga José Ivo Baldani 《Plant and Soil》2013,369(1-2):115-129
Background and Aims
Plant growth-promoting bacteria, mainly diazotrophs and phosphate solubilizers, can reduce the use of chemical fertilizers for rice crops. Here, diazotrophic bacteria isolated from rice were screened for their ability to solubilize inorganic P (Pi) in vitro and in association with rice plants cultivated in pots.Methods
Forty-nine isolates were tested for the ability to solubilize Pi on NBRIP and GL agar plate media and seven selected strains were further evaluated in NBRIP liquid medium. Three of these strains were inoculated in rice plants grown in soil pots containing 15N-labeled fertilizer and two sources of P: tricalcium phosphate (TCP) or simple superphosphate (SSP). The dry matter, yield, N, P, and the 15N content accumulated in plant tissues were measured at 135 days after planting.Results
Seven strains belonging to the genera Herbaspirillum and Burkholderia formed a halo of solubilized Pi on agar plates. The Burkholderia strains showed peak soluble P (around 200 mg P L?1) on the fifth day when grown in NBRIP liquid medium for 14 days. Inoculation of Herbaspirillum strains (H18, ZA15) and a Burkholderia vietaminensis strain (AR114) increased rice grain yield from 33 to 47 % with TCP and 18 to 44 % with TSS, respectively. The bacterial inoculation led to enhanced N-use efficiency of the 15N-labeled fertilizer.Conclusion
These results suggest that the selection and use of P-solubilizing diazotrophic bacteria are a good strategy to promote P solubilization and/or N use efficiency in rice plants. 相似文献22.
VIVIANE LANQUAR ASTRID AGORIO JÉRÔME GIRAUDAT THOMAS ROACH ANJA KRIEGER‐LISZKAY SÉBASTIEN THOMINE 《Plant, cell & environment》2013,36(4):804-817
Cadmium (Cd) is highly toxic to plants causing growth reduction and chlorosis. It binds thiols and competes with essential transition metals. It affects major biochemical processes such as photosynthesis and the redox balance, but the connection between cadmium effects at the biochemical level and its deleterious effect on growth has seldom been established. In this study, two Cd hypersensitive mutants, cad1‐3 impaired in phytochelatin synthase (PCS1), and nramp3nramp4 impaired in release of vacuolar metal stores, have been compared. The analysis combines genetics with measurements of photosynthetic and antioxidant functions. Loss of AtNRAMP3 and AtNRAMP4 function or of PCS1 function leads to comparable Cd sensitivity. Root Cd hypersensitivities conferred by cad1‐3 and nramp3nramp4 are cumulative. The two mutants contrast in their tolerance to oxidative stress. In nramp3nramp4, the photosynthetic apparatus is severely affected by Cd, whereas it is much less affected in cad1‐3. In agreement with chloroplast being a prime target for Cd toxicity in nramp3nramp4, the Cd hypersensitivity of this mutant is alleviated in the dark. The Cd hypersensitivity of nramp3nramp4 mutant highlights the critical role of vacuolar metal stores to supply essential metals to plastids and maintain photosynthetic function under Cd and oxidative stresses. 相似文献
23.
Yasmin Rubio-Palis Mariapia Bevilacqua Domingo Alberto Medina Jorge Ernesto Moreno Lya Cárdenas Víctor Sánchez Yarys Estrada William Anaya ángela Martínez 《Memórias do Instituto Oswaldo Cruz》2013,108(2):220-228
To explore the effects of deforestation and resulting differences in vegetation and land cover on entomological parameters, such as anopheline species composition, abundance, biting rate, parity and entomological inoculation rate (EIR), three villages were selected in the Lower Caura River Basin, state of Bolívar, Venezuela. All-night mosquito collections were conducted between March 2008-January 2009 using CDC light traps and Mosquito Magnet(r) Liberty Plus. Human landing catches were performed between 06:00 pm-10:00 pm, when anophelines were most active. Four types of vegetation were identified. The Annual Parasite Index was not correlated with the type of vegetation. The least abundantly forested village had the highest anopheline abundance, biting rate and species diversity. Anopheles darlingi and Anopheles nuneztovari were the most abundant species and were collected in all three villages. Both species showed unique biting cycles. The more abundantly forested village of El Palmar reported the highest EIR. The results confirmed previous observations that the impacts of deforestation and resulting changes in vegetation cover on malaria transmission are complex and vary locally. 相似文献
24.
Martin J Blaser Maria G Dominguez-Bello Monica Contreras Magda Magris Glida Hidalgo Isidoro Estrada Zhan Gao Jose C Clemente Elizabeth K Costello Rob Knight 《The ISME journal》2013,7(1):85-95
The human skin harbors complex bacterial communities. Prior studies showing high inter-individual variation focused on subjects from developed countries. We therefore compared cutaneous bacterial communities of Amerindians in the Venezuelan Amazon with subjects in the United States. Forearm skin specimens were studied from healthy Amerindians in Platanillal village in Amazonas State, and from healthy persons in New York and Colorado. All skin sampling used similar swab/buffer techniques. Multiplexed V2-targeted 16S rRNA gene pyrosequencing yielded high quality sequences from 112 samples. The results show 20 phyla, with three (Proteobacteria, Firmicutes, Actinobacteria) predominating. US residents and Venezuelan Amerindians had significantly different forearm skin bacterial community compositions, with United States dominated by Propionibacterium. Among the Amerindians, there was a deep split based on bacterial community membership, with 30 and 42 samples, respectively, falling into each of the two groups, not associated with age, gender, or body mass index. One Amerindian group had diversity similar to the United States, but was dominated by Staphylococcus rather than Propionibacterium. The other Amerindian group was significantly more diverse and even than the US or the other Amerindian group, and featured a broad range of Proteobacteria. The results provide evidence that ethnicity, lifestyle and/or geography are associated with the structure of human cutaneous bacterial communities. 相似文献
25.
Guadalupe Chávez-López Roberto Estrada Guadalupe Estrada-Chávez 《Current fungal infection reports》2016,10(3):117-120
Malassezia spp. folliculitis is a variant quite frequent at the tropics. The clinical aspect of perifollicular pustules on an erythematous base with a central hair is the clue for the diagnosis, especially on hairy surfaces. We describe this clinical form caused by Malassezia sp., with background, direct examination findings, and histopathology. 相似文献
26.
Prepubertal children exposed to concentrated disadvantage: An exploratory analysis of inflammation and metabolic dysfunction
下载免费PDF全文
![点击此处可从《Obesity (Silver Spring, Md.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
27.
Rebeca Martínez Teresa Núñez de Villavicencio-Díaz Aniel Sánchez Yassel Ramos Jesús Noda Ferro Lázaro Gil González Milagros Méndez Elsa Rodríguez Ernesto Marcos Belinda Sánchez Yordanka Masforrol Hilda Garay Fernando Albericio Lisset Hermida Luis Javier González Eva Vonasek Mario P Estrada Vladimir Besada 《Biochemistry and Biophysics Reports》2016
BackgroundGrowth hormone secretagogues (GHS), among other factors, regulate the release of GH. The biological activity of the secretagogue peptide A233 as a promoter of growth and innate immunity in teleost fish has previously been demonstrated, but its role in the immune system of mammals is not well understood.MethodsThe effect of the peptide was investigated in J774A.2 macrophage cells using a comparative proteomics approach after 6 and 12 h of peptide stimulation.ResultsThe functional analysis of differentially modulated proteins showed that A233 peptide treatment appears to promote activation and ROS-dependent cytotoxic functions in macrophages and enhanced expression of antiviral protein complexes such as MAVS. In accordance with this hypothesis, we found that A233 treatment enhanced superoxide anion production and the IFN-γ level in J774A.2 cells and mouse splenocytes, respectively, and reduced viral load in a dengue virus mouse model of infection.ConclusionsThe growth hormone secretagogue A233 peptide promotes activation of ROS-dependent cytotoxic functions and exerts immunomodulatory effects that enable an antiviral state in a dengue virus mouse model.General SignificanceThe increase of IFN-γ level and the differential modulation of antiviral proteins by the A233 peptide suggest that the molecule could activate an innate immune response with a possible further impact in the treatment of acute and chronic diseases. 相似文献
28.
Lise Pascale Alejandro López González Audrey Di Giorgio Marc Gaysinski Jordi Teixido Closa Roger Estrada Tejedor 《Journal of biomolecular structure & dynamics》2016,34(11):2327-2338
A series of pentameric “Polyamide Amino Acids” (PAAs) compounds derived from the same trimeric precursor have been synthesized and investigated as HIV TAR RNA ligands, in the absence and in the presence of a Tat fragment. All PAAs bind TAR with similar sub-micromolar affinities but their ability to compete efficiently with the Tat fragment strongly differs, IC50 ranging from 35 nM to >2 μM. While NMR and CD studies reveal that all PAA interact with TAR at the same site and induce globally the same RNA conformational change upon binding, a comparative thermodynamic study of PAA/TAR equilibria highlights distinct TAR binding modes for Tat competitor and non-competitor PAAs. This led us to suggest two distinct interaction modes that have been further validated by molecular modeling studies. While the binding of Tat competitor PAAs induces a contraction at the TAR bulge region, the binding of non-competitor ones widens it. This could account for the distinct PAA ability to compete with Tat fragment. Our work illustrates how comparative thermodynamic studies of a series of RNA ligands of same chemical family are of value for understanding their binding modes and for rationalizing structure-activity relationships. 相似文献
29.
G Cuce S Cetinkaya N Isitez S Kuccukturk ME Sozen S Kalkan 《Biotechnic & histochemistry》2016,91(2):122-127
Methylmethane sulfonate (MMS) is an alkylating agent that may react with DNA and damage it. We investigated histological changes and apoptosis caused by MMS and the effects of curcumin on MMS treated mouse kidneys. Twenty-four mice were divided into four equal groups: controls injected with saline, a group injected with 40 mg/kg MMS, a group injected with 40 mg/kg MMS and given 100 mg/kg curcumin by gavage, and a group given 100 mg/kg curcumin by gavage. MMS caused congestion and vacuole formation, and elevated the apoptotic index significantly, but had no other effect on kidney tissue. Curcumin improved the congestion and vacuole formation caused by MMS and decreased the apoptotic index. Curcumin administered with MMS appears to decrease the deleterious effects of MMS on the kidney. 相似文献
30.