全文获取类型
收费全文 | 434篇 |
免费 | 21篇 |
专业分类
455篇 |
出版年
2023年 | 1篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 3篇 |
2016年 | 18篇 |
2015年 | 27篇 |
2014年 | 17篇 |
2013年 | 28篇 |
2012年 | 35篇 |
2011年 | 45篇 |
2010年 | 21篇 |
2009年 | 20篇 |
2008年 | 15篇 |
2007年 | 38篇 |
2006年 | 21篇 |
2005年 | 31篇 |
2004年 | 18篇 |
2003年 | 22篇 |
2002年 | 13篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1981年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有455条查询结果,搜索用时 11 毫秒
161.
Gui‐Liang Xu Hui Sun Chao Luo Luis Estevez Minghao Zhuang Han Gao Rachid Amine Hao Wang Xiaoyi Zhang Cheng‐Jun Sun Yuzi Liu Yang Ren Steve M. Heald Chunsheng Wang Zonghai Chen Khalil Amine 《Liver Transplantation》2019,9(2)
Lithium/selenium‐sulfur batteries have recently received considerable attention due to their relatively high specific capacities and high electronic conductivity. Different from the traditional encapsulation strategy for suppressing the shuttle effect, an alternative approach to directly bypass polysulfide/polyselenide formation via rational solid‐electrolyte interphase (SEI) design is demonstrated. It is found that the robust SEI layer that in situ forms during charge/discharge via interplay between rational cathode design and optimal electrolytes could enable solid‐state (de)lithiation chemistry for selenium‐sulfur cathodes. Hence, Se‐doped S22.2Se/Ketjenblack cathodes can attain a high reversible capacity with minimal shuttle effects during long‐term and high rate cycling. Moreover, the underlying solid‐state (de)lithiation mechanism, as evidenced by in situ 7Li NMR and in operando synchrotron X‐ray probes, further extends the optimal sulfur confinement pore size to large mesopores and even macropores that have been long considered as inferior sulfur or selenium host materials, which play a crucial role in developing high volumetric energy density batteries. It is expected that the findings in this study will ignite more efforts to tailor the compositional/structure characteristics of the SEI layers and the related ionic transport across the interface by electrode structure, electrolyte solvent, and electrolyte additive screening. 相似文献
162.
To determine whether to use single or multiple predator species for biological pest control requires manipulative field experiments. We performed such tests in Benin (West Africa) in cassava fields infested by the cassava green mite Mononychellus tanajoa, and the cotton red mite Oligonychus gossypii. These fields also harboured the cassava apex-inhabiting predator Typhlodromalus aripo and either the leaf-inhabiting predator Amblydromalus manihoti or Euseius fustis. We manipulated predator species composition on individual plants to determine their effect on prey and predator densities. In fields with T. aripo plus A. manihoti, M. tanajoa densities were reduced by T. aripo alone or together with A. manihoti, but neither of these predators, alone or together, reduced O. gossypii densities. In fields with T. aripo plus E. fustis, T. aripo alone or together with E. fustis exerted significant control over O. gossypii, but weak control over M. tanajoa. Densities of any of the predator species were not affected by co-occurring predator species, suggesting a minor role for intraguild predation in the field, contrary to earlier experiments on small plants in the laboratory. We conclude that (1) T. aripo is the most effective predator species in suppressing M. tanajoa, (2) two predator species, T. aripo and E. fustis, are needed to suppress O. gossypii, and (3) predator species together on the same plant do not negatively affect each other nor the extent to which they control their prey. We argue that intraguild predation is reduced due to partial niche separation among predator species. 相似文献
163.
Jiqiang Ling Rachid Daoud Marc J. Lajoie George M. Church Dieter S?ll B. Franz Lang 《Nucleic acids research》2014,42(1):499-508
The discovery of diverse codon reassignment events has demonstrated that the canonical genetic code is not universal. Studying coding reassignment at the molecular level is critical for understanding genetic code evolution, and provides clues to genetic code manipulation in synthetic biology. Here we report a novel reassignment event in the mitochondria of Ashbya (Eremothecium) gossypii, a filamentous-growing plant pathogen related to yeast (Saccharomycetaceae). Bioinformatics studies of conserved positions in mitochondrial DNA-encoded proteins suggest that CUU and CUA codons correspond to alanine in A. gossypii, instead of leucine in the standard code or threonine in yeast mitochondria. Reassignment of CUA to Ala was confirmed at the protein level by mass spectrometry. We further demonstrate that a predicted is transcribed and accurately processed in vivo, and is responsible for Ala reassignment. Enzymatic studies reveal that is efficiently recognized by A. gossypii mitochondrial alanyl-tRNA synthetase (AgAlaRS). AlaRS typically recognizes the G3:U70 base pair of tRNAAla; a G3A change in Ashbya
abolishes its recognition by AgAlaRS. Conversely, an A3G mutation in Saccharomyces cerevisiae
confers tRNA recognition by AgAlaRS. Our work highlights the dynamic feature of natural genetic codes in mitochondria, and the relative simplicity by which tRNA identity may be switched. 相似文献
164.
165.
Rachid Cheddadi H. John B. Birks Pedro Tarroso Sascha Liepelt Dusan Gömöry Stefan Dullinger Eliane S. Meier Karl Hülber Luigi Maiorano Henri Laborde 《Vegetation History and Archaeobotany》2014,23(2):113-122
At northern temperate latitudes trees have adjusted their ranges substantially in response to changing climates during the Holocene. Results from dispersal model simulations suggest that postglacial migration rates may have been over-estimated from fossil pollen data. As a contribution to this debate, we infer the migration rates of Abies alba (Mill.), silver fir, as a case-study species, by using a spatially explicit approach based on fossil pollen but taking into account its modern genetic diversity pattern. Maximum estimates of migration rates from fossil pollen data alone are higher than 700 m yr?1 during the Holocene. Considering the potential refugia as suggested from all the fossil data but restricting the area over which silver fir expanded from each glacial refugium using data on the current haplotype distribution, the estimated maximum migration rates of silver fir are less than 250 m yr?1. Genetic information may allow for (1) the exclusion of those refugial areas where the species may have survived during the last glacial period but from which it did not spread or spread only very locally and (2) the delineation of the areas over which the species spread from each glacial refugium. The estimated rates in the present study are generally consistent with rates suggested from modelling approaches. This study shows that integrating fossil pollen records can improve simulations of dispersal processes and, thus, allow for better predictions of future changes in tree species’ ranges. 相似文献
166.
167.
José A. Siles Caio T. C. C. Rachid Inmaculada Sampedro Inmaculada García-Romera James M. Tiedje 《PloS one》2014,9(7)
The Mediterranean basin has been identified as a biodiversity hotspot, about whose soil microbial diversity little is known. Intensive land use and aggressive management practices are degrading the soil, with a consequent loss of fertility. The use of organic amendments such as dry olive residue (DOR), a waste produced by a two-phase olive-oil extraction system, has been proposed as an effective way to improve soil properties. However, before its application to soil, DOR needs a pre-treatment, such as by a ligninolytic fungal transformation, e.g. Coriolopsis floccosa. The present study aimed to describe the bacterial and fungal diversity in a Mediterranean soil and to assess the impact of raw DOR (DOR) and C. floccosa-transformed DOR (CORDOR) on function and phylogeny of soil microbial communities after 0, 30 and 60 days. Pyrosequencing of the 16S rRNA gene demonstrated that bacterial diversity was dominated by the phyla Proteobacteria, Acidobacteria, and Actinobacteria, while 28S-rRNA gene data revealed that Ascomycota and Basidiomycota accounted for the majority of phyla in the fungal community. A Biolog EcoPlate experiment showed that DOR and CORDOR amendments decreased functional diversity and altered microbial functional structures. These changes in soil functionality occurred in parallel with those in phylogenetic bacterial and fungal community structures. Some bacterial and fungal groups increased while others decreased depending on the relative abundance of beneficial and toxic substances incorporated with each amendment. In general, DOR was observed to be more disruptive than CORDOR. 相似文献
168.
Yoav Peretz Zhong He Yu Shi Bader Yassine-Diab Jean-Philippe Goulet Rebeka Bordi Ali Filali-Mouhim Jean-Baptiste Loubert Mohamed El-Far Franck P. Dupuy Mohamed Rachid Boulassel C��cile Tremblay Jean-Pierre Routy Nicole Bernard Robert Balderas Elias K. Haddad Rafick-Pierre S��kaly 《PLoS pathogens》2012,8(8)
169.
We derive a new method to estimate the age specific incidence of an infection with a differential mortality, using individual level infection status data from successive surveys. The method consists of a) an SI-type model to express the incidence rate in terms of the prevalence and its derivatives as well as the difference in mortality rate, and b) a maximum likelihood approach to estimate the prevalence and its derivatives. Estimates can in principle be obtained for any chosen age and time, and no particular assumptions are made about the epidemiological or demographic context. This is in contrast with earlier methods for estimating incidence from prevalence data, which work with aggregated data, and the aggregated effect of demographic and epidemiological rates over the time interval between prevalence surveys. Numerical simulation of HIV epidemics, under the presumption of known excess mortality due to infection, shows improved control of bias and variance, compared to previous methods. Our analysis motivates for a) effort to be applied to obtain accurate estimates of excess mortality rates as a function of age and time among HIV infected individuals and b) use of individual level rather than aggregated data in order to estimate HIV incidence rates at times between two prevalence surveys. 相似文献
170.
Mehri S Mahjoub S Hammami S Zaroui A Frih A Betbout F Mechmeche R Hammami M 《Molecular biology reports》2012,39(4):4059-4065
Essential hypertension (HTA) is the clinical expression of a disordered interaction between the genetic, physiological, and
biochemical systems that under usual conditions maintain cardiovascular homeostasis. We studied the effects of the angiotensinogen
M235T, angiotensin converting enzyme insertion/deletion (ACE I/D), and angiotensin II receptor 1 (AT1R) A1166C gene polymorphisms
on the risk of HTA and to evaluate the relationship between these polymorphisms and obesity. We performed AGT, ACE and AGTR
genotyping in 142 hypertensive patients and 191 control subjects using PCR-RFLP methods and PCR, respectively. The three polymorphisms
were significantly associated with HTA. Individuals carrying the mutated TT of AGT, DD of ACE and CC of AT1R genotypes had
an 1.67 (P = 0.032), 3.09 (P < 0.001) and 3.45 (P < 0.001)-fold increased risk of HTA. After adjustment for sex, smoking, diabetes, dyslipidemia, BMI, triglycerides and DD,
TT and CC genotypes, BMI was independent risk factor of HTA (OR = 3.14; P < 0.001). An association of BMI with ACE gene polymorphism (P = 0.035), whereas no association with AGT and AT1R gene polymorphisms was obtained. The proportion of hypertensives is as
high as 21.8 and 13.4% in the overweight and the obese DD group. The present study implies that the genotyping for the variants
of RAS gene could in the future become an important part of the clinical process of risk identification for HTA. 相似文献