全文获取类型
收费全文 | 136篇 |
免费 | 11篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 2篇 |
2015年 | 7篇 |
2014年 | 5篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 8篇 |
2006年 | 3篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 10篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1974年 | 2篇 |
1970年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有147条查询结果,搜索用时 15 毫秒
81.
Bajerová M Krejčová K Rabišková M Muselík J Dvořáčková K Gajdziok J Masteiková R 《AAPS PharmSciTech》2011,12(4):1348-1357
The aim of this study was to develop novel hydrogel-based beads and characterize their potential to deliver and release a
drug exhibiting pH-dependent solubility into distal parts of gastrointestinal (GI) tract. Oxycellulose beads containing diclofenac
sodium as a model drug were prepared by the ionotropic external gelation technique using calcium chloride solution as the
cross-linking medium. Resulting beads were characterized in terms of particle shape and size, encapsulation efficacy, swelling
ability and in vitro drug release. Also, potential drug–polymer interactions were evaluated using Fourier transform infrared spectroscopy. The
particle size was found to be 0.92–0.96 mm for inactive (oxycellulose only) and 1.47–1.60 mm for active (oxycellulose–diclofenac
sodium) beads, respectively. In all cases, the sphericity factor was between 0.70 and 0.81 with higher values observed for
samples containing higher polymer and drug concentrations. The swelling of inactive beads was found to be strongly influenced
by the pH and composition (i.e. Na+ concentration) of the selected media (simulated gastric fluid vs. phosphate buffer pH 6.8). The encapsulation efficiency of the prepared particles ranged from 58% to 65%. Results of dissolution
tests showed that the drug loading inside of the particles influenced the rate of its release. In general, prepared particles
were able to release the drug within 12–16 h after a lag time of 4 h. Fickian diffusion was found as the predominant drug release mechanism. Thus, this novel particulate system showed
a good potential to deliver drugs specifically to the distal parts of the human GI tract. 相似文献
82.
Evolution of parental incubation behaviour in dinosaurs cannot be inferred from clutch mass in birds
A recent study proposed that incubation behaviour (i.e. type of parental care) in theropod dinosaurs can be inferred from an allometric analysis of clutch volume in extant birds. However, the study in question failed to account for factors known to affect egg and clutch size in living bird species. A new scaling analysis of avian clutch mass demonstrates that type of parental care cannot be distinguished by conventional allometry because of the confounding effects of phylogeny and hatchling maturity. Precociality of young but not paternal care in the theropod ancestors of birds is consistent with the available data. 相似文献
83.
Devasuda Anblagan Nia W. Jones Carolyn Costigan Alexander J. J. Parker Kirsty Allcock Rosanne Aleong Lucy H. Coyne Ruta Deshpande Nick Raine-Fenning George Bugg Neil Roberts Zdenka Pausova Tomá? Paus Penny A. Gowland 《PloS one》2013,8(7)
Objective
To study whether maternal cigarette smoking during pregnancy is associated with alterations in the growth of fetal lungs, kidneys, liver, brain, and placenta.Design
A case-control study, with operators performing the image analysis blinded.Setting
Study performed on a research-dedicated magnetic resonance imaging (MRI) scanner (1.5 T) with participants recruited from a large teaching hospital in the United Kingdom.Participants
A total of 26 pregnant women (13 current smokers, 13 non smokers) were recruited; 18 women (10 current smokers, 8 nonsmokers) returned for the second scan later in their pregnancy.Methods
Each fetus was scanned with MRI at 22–27 weeks and 33–38 weeks gestational age (GA).Main outcome measures
Images obtained with MRI were used to measure volumes of the fetal brain, kidneys, lungs, liver and overall fetal size, as well as placental volumes.Results
Exposed fetuses showed lower brain volumes, kidney volumes, and total fetal volumes, with this effect being greater at visit 2 than at visit 1 for brain and kidney volumes, and greater at visit 1 than at visit 2 for total fetal volume. Exposed fetuses also demonstrated lower lung volume and placental volume, and this effect was similar at both visits. No difference was found between the exposed and nonexposed fetuses with regards to liver volume.Conclusion
Magnetic resonance imaging has been used to show that maternal smoking is associated with reduced growth of fetal brain, lung and kidney; this effect persists even when the volumes are corrected for maternal education, gestational age, and fetal sex. As expected, the fetuses exposed to maternal smoking are smaller in size. Similarly, placental volumes are smaller in smoking versus nonsmoking pregnant women. 相似文献84.
Tutkuviene J Morkuniene R Bartkute K Drazdiene N 《Anthropologischer Anzeiger; Bericht über die biologisch-anthropologische Literatur》2011,68(4):471-484
The purpose of this study was to analyse body size indices of newborns in Vilnius city (Lithuania) during 2005-2010 in relation with mother's education and ethnicity, and in parallel with the changes of socio-economic situation during the recent years. The present results were based on data (N = 18,084) from the Vilnius University Clinic of Obstetrics and Gynaecology. Comparison of the present Lithuanian data with other newborn studies was made. The analysis of socio-economic and demographic indicators of Lithuania, and the comparison of Gross Domestic Product of various countries was performed. The comparison of body size of newborns' data from the different countries showed that Lithuanian newborns were among the biggest babies. Some statistically significant differences in body size of newborns from different ethnic groups were established. Body length of Lithuanian newborns (M = 52.6 cm, SD = 2.5) was higher than length of Russian, Ukrainian and Romanian newborns. Body weight of Lithuanian newborns (M = 3511 g, SD = 485) was bigger than birth weight of Russian, Polish, Ukrainian and Romanian newborns. The analysis of newborns size by mother's education showed that body weight of neonates from mothers with the university education and from each other education group was bigger in comparison with the babies from respectively lower education group. The comparison of newborns weight by mother's ethnicity in relation to education level revealed nearly no discrepancies between size of newborns from mothers with the same education level at different ethnic group. The analysis of birth parameters by year has not established a statistically significant difference between the mean values for the body weight and body length of the whole investigated contingent of the full-term, single-birth newborns from Vilnius city during the 2005-2010. However, the tendency has been revealed that newborns from mothers with lower education were the most susceptible to negative economic changes after the 2008. 相似文献
85.
Jone Vencloviene Ruta Babarskiene Irena Milvidaite Raimondas Kubilius Jolanta Stasionyte 《International journal of biometeorology》2014,58(6):1295-1303
A number of studies have established the effects of solar-geomagnetic activity on the human cardio-vascular system. It is plausible that the heliophysical conditions existing during and after hospital admission may affect survival in patients with acute coronary syndromes (ACS). We analyzed data from 1,413 ACS patients who were admitted to the Hospital of Kaunas University of Medicine, Lithuania, and who survived for more than 4 days. We evaluated the associations between active-stormy geomagnetic activity (GMA), solar proton events (SPE), and solar flares (SF) that occurred 0–3 days before and after admission, and 2-year survival, based on Cox’s proportional-hazards model, controlling for clinical data. After adjustment for clinical variables, active-stormy GMA on the 2nd day after admission was associated with an increased (by 1.58 times) hazard ratio (HR) of cardiovascular death (HR?=?1.58, 95 % CI 1.07–2.32). For women, geomagnetic storm (GS) 2 days after SPE occurred 1 day after admission increased the HR by 3.91 times (HR?=?3.91, 95 % CI 1.31–11.7); active-stormy GMA during the 2nd–3rd day after admission increased the HR by over 2.5 times (HR?=?2.66, 95 % CI 1.40–5.03). In patients aged over 70 years, GS occurring 1 day before or 2 days after admission, increased the HR by 2.5 times, compared to quiet days; GS in conjunction with SF on the previous day, nearly tripled the HR (HR?=?3.08, 95 % CI 1.32–7.20). These findings suggest that the heliophysical conditions before or after the admission affect the hazard ratio of lethal outcome; adjusting for clinical variables, these effects were stronger for women and older patients. 相似文献
86.
Lavinia L. Ruta Valentina C. Popa Ioana Nicolau Andrei F. Danet Virgil Iordache Aurora D. Neagoe Ileana C. Farcasanu 《FEBS letters》2014
The involvement of Ca2+ in the response to high Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Hg2+ was investigated in Saccharomyces cerevisiae. The yeast cells responded through a sharp increase in cytosolic Ca2+ when exposed to Cd2+, and to a lesser extent to Cu2+, but not to Mn2+, Co2+, Ni2+, Zn2+, or Hg2+. The response to high Cd2+ depended mainly on external Ca2+ (transported through the Cch1p/Mid1p channel) but also on vacuolar Ca2+ (released into the cytosol through the Yvc1p channel). The adaptation to high Cd2+ was influenced by perturbations in Ca2+ homeostasis. Thus, the tolerance to Cd2+ often correlated with sharp Cd2+-induced cytosolic Ca2+ pulses, while the Cd2+ sensitivity was accompanied by the incapacity to rapidly restore the low cytosolic Ca2+. 相似文献
87.
Navnith K. P. Kumaran Damodaran Padmalal Madhavan K. Nair Ruta B. Limaye Jaswant S. Guleria Rashmi Srivastava Anumeha Shukla 《PloS one》2014,9(4)
The high rainfall and low sea level during Early Holocene had a significant impact on the development and sustenance of dense forest and swamp-marsh cover along the southwest coast of India. This heavy rainfall flooded the coastal plains, forest flourishing in the abandoned river channels and other low-lying areas in midland.The coastline and other areas in lowland of southwestern India supply sufficient evidence of tree trunks of wet evergreen forests getting buried during the Holocene period under varying thickness of clay, silty-clay and even in sand sequences. This preserved subfossil log assemblage forms an excellent proxy for eco-geomorphological and palaeoclimate appraisal reported hitherto from Indian subcontinent, and complements the available palynological data. The bulk of the subfossil logs and partially carbonized wood remains have yielded age prior to the Holocene transgression of 6.5 k yrs BP, suggesting therein that flooding due to heavy rainfall drowned the forest cover, even extending to parts of the present shelf. These preserved logs represent a unique palaeoenvironmental database as they contain observable cellular structure. Some of them can even be compared to modern analogues. As these woods belong to the Late Pleistocene and Holocene, they form a valuable source of climate data that alleviates the lack of contemporaneous meteorological records. These palaeoforests along with pollen proxies depict the warmer environment in this region, which is consistent with a Mid Holocene Thermal Maximum often referred to as Holocene Climate Optimum. Thus, the subfossil logs of tropical evergreen forests constitute new indices of Asian palaeomonsoon, while their occurrence and preservation are attributed to eco-geomorphology and hydrological regimes associated with the intensified Asian Summer Monsoon, as recorded elsewhere. 相似文献
88.
Benediktas Juodka Sofija Sasnauskiene Ruta Petniunaite 《Nucleosides, nucleotides & nucleic acids》2013,32(8):1445-1453
Abstract RNA ligase active center model compounds-adenylyl-(5′N?)-lysylpeptides were synthesized. The stability of these compounds in aqueous solutions was studied and it was shown, that the carboxyl group of lysine and glutamic acid or hydroxyl group of threonine have no effect upon the hydrolytic mechanism of the adenylyl-(5′N?)-lysylpeptides. This led to conclusion, that the hydrolysis of the AMP-RNA ligase complex is dependant upon other amino acid functional groups, which may be located next to the phosphoamide center, as a result of tertiary protein structure. 相似文献
89.
Ileana C. Farcasanu Radu Mitrica Ligia Cristache Ioana Nicolau Lavinia L. Ruta Liliana Paslaru Sorin Comorosan 《FEBS letters》2013
Optical manipulation of Saccharomyces cerevisiae cells with high density green photons conferred protection against the deleterious effects of UV radiation. Combining chemical screening with UV irradiation of yeast cells, it was noted that the high density green photons relied on the presence of intact unfolded protein response (UPR) pathway to exert their protective effect and that the low Ca2+ conditions boosted the effect. UPR chemical inducers tunicamycin, dithiotreitol and calcium chelators augmented the green light effect in a synergic action against UV-induced damage. Photo-manipulation of cells was a critical factor since the maximum protection was achieved only when cells were pre-exposed to green light. 相似文献
90.
Jone Vencloviene Ruta Babarskiene Rimvydas Slapikas Gintare Sakalyte 《International journal of biometeorology》2013,57(5):797-804
It has been found that solar and geomagnetic activity affects the cardiovascular system. Some evidence has been reported on the increase in the rate of myocardial infarction, stroke and myocardial infarction related deaths during geomagnetic storms. We investigated the association between cardiovascular characteristics of patients, admitted for myocardial infarction with ST elevation (STEMI), and geomagnetic activity (GMA), solar proton events (SPE), solar flares, and meteorological variables during admission. The data of 1,979 patients hospitalized at the Hospital of Lithuanian University of Health Sciences (Kaunas) were analyzed. We evaluated the association between environmental variables and patient’s characteristics by multivariate logistic regression, controlling patient’s gender and age. Two days after geomagnetic storms the risk of STEMI was over 1.5 times increased in patients who had a medical history of myocardial infarction, stable angina, renal or pulmonary diseases. The dose–response association between GMA level and STEMI risk for patients with renal diseases in history was observed. Two days after SPE the risk of STEMI in patients with stable angina in anamnesis was increased over 1.5 times, adjusting by GMA level. The SPE were associated with an increase of risk for patients with renal diseases in history. This study confirms the strongest effect of phenomena in the Sun in high risk patients. 相似文献