全文获取类型
收费全文 | 170篇 |
免费 | 12篇 |
专业分类
182篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 11篇 |
2014年 | 7篇 |
2013年 | 18篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 13篇 |
2007年 | 10篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有182条查询结果,搜索用时 0 毫秒
41.
Jack?A?TuszynskiEmail author Philip?Winter Diana?White Chih-Yuan?Tseng Kamlesh?K?Sahu Francesco?Gentile Ivana?Spasevska Sara?Ibrahim?Omar Niloofar?Nayebi Cassandra?DM?Churchill Mariusz?Klobukowski Rabab?M?Abou?El-Magd 《Theoretical biology & medical modelling》2014,11(1):52
A variety of topics are reviewed in the area of mathematical and computational modeling in biology, covering the range of scales from populations of organisms to electrons in atoms. The use of maximum entropy as an inference tool in the fields of biology and drug discovery is discussed. Mathematical and computational methods and models in the areas of epidemiology, cell physiology and cancer are surveyed. The technique of molecular dynamics is covered, with special attention to force fields for protein simulations and methods for the calculation of solvation free energies. The utility of quantum mechanical methods in biophysical and biochemical modeling is explored. The field of computational enzymology is examined. 相似文献
42.
Angelo PC Nunes-Silva CG Brígido MM Azevedo JS Assunção EN Sousa AR Patrício FJ Rego MM Peixoto JC Oliveira WP Freitas DV Almeida ER Viana AM Souza AF Andrade EV Acosta PO Batista JS Walter ME Leomil L Anjos DA Coimbra RC Barbosa MH Honda E Pereira SS Silva A Pereira JO Silva ML Marins M Holanda FJ Abreu RM Pando SC Gonçalves JF Carvalho ML Leal-Mesquita ER da Silveira MA Batista WC Atroch AL França SC Porto JI Schneider MP 《Plant cell reports》2008,27(1):117-124
Guarana (Paullinia cupana var. sorbilis) is a plant native to the central Amazon basin. Roasted seed extracts have been used as medicinal beverages since pre-Colombian
times, due to their reputation as stimulants, aphrodisiacs, tonics, as well as protectors of the gastrointestinal tract. Guarana
plants are commercially cultivated exclusively in Brazil to supply the national carbonated soft-drink industry and natural
product stores around the world. In this report, we describe and discuss the annotation of 15,387 ESTs from guarana seeded-fruits,
highlighting sequences from the flavonoid and purine alkaloid pathways, and those related to biotic stress avoidance. This
is the largest set of sequences registered for the Sapindaceae family. 相似文献
43.
44.
Brian J. Goodfellow Iven C. N. Duarte Anjos L. Macedo Brian F. Volkman Sofia G. Nunes I. Moura John L. Markley José J. G. Moura 《Journal of biological inorganic chemistry》2010,15(3):409-420
The Ni(II) and Zn(II) derivatives of Desulfovibrio vulgaris rubredoxin (DvRd) have been studied by NMR spectroscopy to probe the structure at the metal centre. The βCH2 proton pairs from the cysteines that bind the Ni(II) atom have been identified using 1D nuclear Overhauser enhancement (NOE)
difference spectra and sequence specifically assigned via NOE correlations to neighbouring protons and by comparison with
the published X-ray crystal structure of a Ni(II) derivative of Clostridium pasteurianum rubredoxin. The solution structures of DvRd(Zn) and DvRd(Ni) have been determined and the paramagnetic form refined using
pseudocontact shifts. The determination of the magnetic susceptibility anisotropy tensor allowed the contact and pseudocontact
contributions to the observed chemical shifts to be obtained. Analysis of the pseudocontact and contact chemical shifts of
the cysteine Hβ protons and backbone protons close to the metal centre allowed conclusions to be drawn as to the geometry
and hydrogen-bonding pattern at the metal binding site. The importance of NH–S hydrogen bonds at the metal centre for the
delocalization of electron spin density is confirmed for rubredoxins and can be extrapolated to metal centres in Cu proteins:
amicyanin, plastocyanin, stellacyanin, azurin and pseudoazurin. 相似文献
45.
46.
Laercio Martins De Stefano Alex Lombardi Barbosa Ferraz Ana Lúcia dos Anjos Ferreira Ana Lúcia Gut Ana Lúcia Cogni Elaine Farah Beatriz Bojikian Matsubara 《PloS one》2013,8(10)
Purpose
To investigate the predictors of intolerance to beta-blockers treatment and the 6-month mortality in hospitalized patients with acute coronary syndrome (ACS).Methods
This was a single-center, prospective, and longitudinal study including 370 consecutive ACS patients in Killip class I or II. BBs were prescribed according to international guidelines and withdrawn if intolerance occurred. The study was approved by the institutional ethics committee of our university. Statistics: the clinical parameters evaluated at admission, and the related intolerance to BBs and death at 6 months were analyzed using logistic regression (p<0.05)in PATIENTS.Results
BB intolerance was observed in 84 patients and was associated with no prior use of statins (OR: 2.16, 95%CI: 1.26–3.69, p= 0.005) and Killip class II (OR: 2.5, 95%CI: 1.30-4.75, p=0.004) in the model adjusted for age, sex, blood pressure, and renal function. There was no association with ST-segment alteration or left anterior descending coronary artery plaque. Intolerance to BB was associated with the greatest risk of death (OR: 4.5, 95%CI: 2.15–9.40, p<0.001).Conclusions
After ACS, intolerance to BBs in the first 48 h of admission was associated to non previous use of statin and Killip class II and had a high risk of death within 6 months. 相似文献47.
Background
The diversity of parasites attacking a host varies substantially among different host species. Understanding the factors that explain these patterns of parasite diversity is critical to identifying the ecological principles underlying biodiversity. Seabirds (Charadriiformes, Pelecaniformes and Procellariiformes) and their ectoparasitic lice (Insecta: Phthiraptera) are ideal model groups in which to study correlates of parasite species richness. We evaluated the relative importance of morphological (body size, body weight, wingspan, bill length), life-history (longevity, clutch size), ecological (population size, geographical range) and behavioural (diving versus non-diving) variables as predictors of louse diversity on 413 seabird hosts species. Diversity was measured at the level of louse suborder, genus, and species, and uneven sampling of hosts was controlled for using literature citations as a proxy for sampling effort. 相似文献48.
The Cecropia spp. (Cecropiaceae) trees are attacked by several insects; among them, Coelomera lanio (Dalman) (Coleoptera: Chrysomelidae). The reproductive behavior of C. lanio was studied under laboratory conditions (12 hour photoperiod, 24.1 +/- 0.1 degrees C and mean relative humidity 67.7 +/- 0.6%), in Vi?osa, Minas Gerais, Brazil. The insects were reared in cages and in Petri dishes and fed leaves of Cecropia pachystachya Trec. Reproductive activity began 5.8 +/- 0.2 days after adult emergence and mean copulation time was 2.5 +/- 0.1 min. The female began oviposition only after 25.7 +/- 0.7 days. Each female laid a mean of 4.7 +/- 0.4 times (range 1-9). The mean number of eggs per oviposition and female was 129.2 +/- 2.4 and 587.4 +/- 92.1 respectively, and the time between egg-layings averaged 16.3 +/- 0.8 days. 相似文献
49.
Brian?DM?TomEmail author Walter?R?Gilks Elizabeth?T?Brooke-Powell James?W?Ajioka 《BMC bioinformatics》2005,6(1):234
Background
A common feature of microarray experiments is the occurence of missing gene expression data. These missing values occur for a variety of reasons, in particular, because of the filtering of poor quality spots and the removal of undefined values when a logarithmic transformation is applied to negative background-corrected intensities. The efficiency and power of an analysis performed can be substantially reduced by having an incomplete matrix of gene intensities. Additionally, most statistical methods require a complete intensity matrix. Furthermore, biases may be introduced into analyses through missing information on some genes. Thus methods for appropriately replacing (imputing) missing data and/or weighting poor quality spots are required. 相似文献50.
Luiz Carlos S. Lopez Marcos S. L. Figueiredo Maria Paula de Aguiar Fracasso Daniel Oliveira Mesquita Ulisses Umbelino Anjos Carlos Eduardo Viveiros Grelle 《Ecology and evolution》2016,6(5):1447-1456
Our objective was to estimate and analyze the body‐size distribution parameters of terrestrial mammal assemblages at different spatial scales, and to determine whether these parameters are controlled by local ecological processes or by larger‐scale ones. Based on 93 local assemblages, plus the complete mammal assemblage from three continents (Africa, North, and South America), we estimated three key distribution parameters (diversity/size slope, skewness, and modal size) and compared the values to those expected if size distributions are mainly controlled by local interactions. Mammal diversity decreased much faster as body size increased than predicted by fractal niche theory, both at continental and at local scales, with continental distributions showing steeper slopes than the localities within them. South America showed a steeper slope (after controlling for species diversity), compared to Africa and North America, at local and continental scales. We also found that skewness and modal body size can show strikingly different correlations with predictor variables, such as species richness and median size, depending on the use of untransformed versus log‐transformed data, due to changes in the distribution density generated by log‐transformation. The main differences in slope, skewness, and modal size between local and continental scales appear to arise from the same biogeographical process, where small‐sized species increase in diversity much faster (due to higher spatial turnover rates) than large‐sized species. This process, which can operate even in the absence of competitive saturation at local scales, generates continental assemblages with steeper slopes, smaller modal sizes, and higher right skewness (toward small‐sized species) compared to local communities. In addition, historical factors can also affect the size distribution slopes, which are significantly steeper, in South American mammal assemblages (probably due to stronger megafauna extinction events in South America) than those in North America and Africa. 相似文献