全文获取类型
收费全文 | 1287篇 |
免费 | 54篇 |
国内免费 | 1篇 |
专业分类
1342篇 |
出版年
2024年 | 2篇 |
2023年 | 18篇 |
2022年 | 14篇 |
2021年 | 31篇 |
2020年 | 21篇 |
2019年 | 16篇 |
2018年 | 27篇 |
2017年 | 30篇 |
2016年 | 55篇 |
2015年 | 47篇 |
2014年 | 71篇 |
2013年 | 87篇 |
2012年 | 113篇 |
2011年 | 108篇 |
2010年 | 77篇 |
2009年 | 61篇 |
2008年 | 92篇 |
2007年 | 67篇 |
2006年 | 80篇 |
2005年 | 70篇 |
2004年 | 72篇 |
2003年 | 72篇 |
2002年 | 55篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有1342条查询结果,搜索用时 0 毫秒
91.
The use of tissue expander base as an internal nasal splint 总被引:3,自引:0,他引:3
Eroğlu L Güneren E Akbaş H Demir A Karacalar A 《Plastic and reconstructive surgery》2003,111(2):942-943
92.
Baydar T Papp A Aydin A Nagymajtenyi L Schulz H Isimer A Sahin G 《Biological trace element research》2003,92(3):231-244
The present study was undertaken to examine possible aluminum (Al) accumulation in the brain of rats and to investigate whether
subchronic exposure to the metal leads to behavioral and neurophysiological changes in both treated and control groups. Each
of the groups consisted of 10 animals. Aluminum chloride (AlCl3) at a low (50 mg/kg/d) or high (200 mg/kg/d) dose was applied to male Wistar rats by gavage for 8 wk. Al-free water by gavage
was given to the control group throughout the experiment. Behavioral effects were evaluated by open-field (OF) motor activity
and by acoustic startle response (ASR). Electrophysiological examination was done by recording spontaneous activity and sensory-evoked
potentials from the visual, somatosensory, as well as auditory cortex. The Al content of each whole brain was determined by
electrothermal atomic absorption spectrophotometry. Subchronic Al exposure slightly caused some changes in the evoked potentials
and electrocorticograms and in the OF and ASR performance, but these results were not statistically significant. The brain
Al levels of the control and the low and high dose of Al-exposed groups were measured as 0.717±0.208 μg/g (wet weight), 0.963±0.491
μg/g (wet weight) and 1.816±1.157 μg/g (wet weight), respectively. 相似文献
93.
Sezai Ercisli Ahmet Esitken Rustem Cangi Fikrettin Sahin 《Plant Growth Regulation》2003,41(2):133-137
During the winters of 2001 and 2002, the effects of three strain of Agrobacterium rubi (A1, A16 and A18), a range of IBA concentrations (0, 2000, 4000 and 6000 ppm) alone and in combination with three strains of Agrobacterium rubi and date of cutting collection on the rooting of hardwood stem cuttings of kiwifruit cv. Hayward were evaluated. Treatments of hardwood stem cuttings of kiwifruit cv. Hayward with the bacteria, IBA and IBA plus bacteria were found to promote rooting. Highest rooting percentage was obtained from cuttings treated with 4000 ppm IBA plus A18 in cv. Hayward in both years. Higher rooting percentages were observed when shoots were collected in February rather than in January. 相似文献
94.
95.
96.
Goren AC Bilsel G Bilsel M Demir H Kocabaş EE 《Zeitschrift für Naturforschung. C, Journal of biosciences》2003,58(9-10):687-690
The water-distilled essential oil the leaves of Coridothymus capitatus were analyzed by GC/MS and also analyzed by direct thermal desorption GC/MS. Comparison was made between two analyses techniques. The essential oil consisted mainly of monoterpenes 98.9%, while oxygenated hydrocarbons were identified as 55.6 % and non-oxygenated hydrocarbons as 43.6%. As major components were found carvacrol (35.6%), p-cymene (21.0%), thymol (18.6%), gamma-terpinene (12.3%), alpha-terpinene (3.2%), beta-myrcene (3.0%) and alpha-thujene (1.3%) by hydrodistillation and by the GC/MS method. The direct thermal desorption GC/MS analysis also showed the same major components, namely carvacrol (51.6%), thymol (21.7%), p-cymene (9.7%) gamma-terpinene (8.2%), alpha-terpinene (1.64%). The essential oil of C. capitatus showed strong activity against S. aureus, P. vulgaris, P. aeruginosa, E. coli, K. pneumonia, B. 相似文献
97.
Bayrak A Bayrak T Demirpençe E Kılınç K 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(1):49-55
Human serum paraoxonase 1 (PON1) is a HDL-associated enzyme that catalyzes the hydrolysis of a variety of aromatic carboxylic acid esters and several organophosphates. Recently it has been suggested that a physiological substrate of serum PON1 is homocysteine thiolactone which is a putative risk factor in atherosclerosis. In this study, human (192)Q and (192)R PON1 isoenzymes were purified from the respective phenotype human serum, using a protocol consisting of ammonium sulfate precipitation and four chromatography steps: gel filtration, ion-exchange, non-specific affinity, and a second ion-exchange. Using paraoxon as substrate, overall purification fold was found as 742 for (192)R PON1 and 590 for (192)Q PON1. The final purified enzymes were shown as single protein bands close to 45kDa on SDS-PAGE and confirmed by Western blot. Substrate kinetics were studied with phenyl acetate, paraoxon and homocysteine thiolactone. Both PON1 isoenzymes showed mixed type inhibition with phenyl acetate. K(m) values of (192)Q and (192)R PON1 for homocysteine thiolactone were 23.5mM and 22.6mM respectively. For (192)R PON1, the V(max) was 2.5-fold and k(cat)/K(m) was 2.6-fold higher than those for (192)Q PON1 when homocysteine thiolactone is used as substrate. The present data suggest that defining (192)Q and (192)R PON1 isoforms could be a good predictor and prognostic marker in the cardiovascular risk assessment. 相似文献
98.
99.
Ozturk A Baltaci AK Mogulkoc R Oztekin E Sivrikaya A Kurtoglu E Kul A 《Biological trace element research》2003,94(2):157-166
The aim of the study was to investigate the effects of zinc deficiency and supplementation on lipid peroxidation and glutathione
levels in blood and in some tissues of rats performing swimming exercise. Forty adult male Sprague-Dawley rats were divided
into four groups: group 1, zinc-deficient consisted of swimming rats; group 2 consisted of zinc-supplemented swimming rats;
groups 3 and 4 were the swimming and nonswimming controls, respectively. The levels of malondialdehyde and glutathione were
measured after 4 wk of zinc-deficient or zinc-supplemented diet and 30 min of swimming exercise daily.
The erythrocyte glutathione levels of groups 2 and 4 were significantly higher than those of groups 1 and 3 (p<0.01). The plasma malondialdehyde level of group 1 was significantly higher than all other groups. The glutathione levels
in liver, kidney, striated muscle, and testes of group 2 were higher than in the other groups (p<0.01) and higher in kidney and striated muscle of group 3 than in groups 1 and 4 (p<0.01). The tissue malondialdehyde levels of striated muscle, liver, kidney, and testes of group 1 were significantly higher
than for all other groups (p<0.01). Our findings suggest that both swimming exercise and zinc deficiency result in an increase of lipid peroxidation in
tissues and that zinc supplementation prevents these alterations by the activation of the antioxidant system. 相似文献
100.
Somatic hybridization for citrus rootstock breeding: an effective tool to solve some important issues of the Mediterranean citrus industry 总被引:2,自引:0,他引:2
Dambier D Benyahia H Pensabene-Bellavia G Aka Kaçar Y Froelicher Y Belfalah Z Lhou B Handaji N Printz B Morillon R Yesiloglu T Navarro L Ollitrault P 《Plant cell reports》2011,30(5):883-900
The prevalence of sour orange rootstock in the southern and eastern part of the Mediterranean Basin is presently threatened by the spread of Citrus Tristeza Virus (CTV) and its main vector Toxoptera citricida, combined with abiotic constraints such as drought, salinity and alkalinity. The search for alternative CTV-resistant rootstocks that also withstand the other constraints is now considered an urgent priority for a sustainable citrus industry in the area. Complementary progenitors can be found in citrus germplasm to combine the desired traits, particularly between Poncirus and Citrus genera. The production of somatic hybrids allows cumulating all dominant traits irrespective of their heterozygosity level, and would appear to be an effective way to solve the rootstock challenge facing the Mediterranean citrus industry. This paper presents the results obtained during a regional collaborative effort between five countries, to develop new rootstocks by somatic hybridization. New embryogenic callus lines to be used for somatic hybridization have been created. Protoplast fusions have been performed at CIRAD and IVIA laboratories, focusing on intergeneric combinations. Analysis of ploidy level by flow cytometry and molecular markers confirmed the acquisition of new interesting tetraploid somatic hybrids for six combinations. Diploid cybrids with intergeneric (Citrus?×?Poncirus) nucleus and C. reticulata or C. aurantifolia mitochondria were also identified for four combinations. The agronomical performance of a pre-existing somatic hybrid between Poncirus trifoliata and Citrus reticulata was validated in calcareous soils in Morocco. Somatic hybridization is now integrated into the breeding programs of the five Mediterranean countries. 相似文献