全文获取类型
收费全文 | 638篇 |
免费 | 38篇 |
国内免费 | 2篇 |
专业分类
678篇 |
出版年
2023年 | 10篇 |
2022年 | 12篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 23篇 |
2015年 | 28篇 |
2014年 | 26篇 |
2013年 | 42篇 |
2012年 | 48篇 |
2011年 | 74篇 |
2010年 | 46篇 |
2009年 | 31篇 |
2008年 | 50篇 |
2007年 | 53篇 |
2006年 | 31篇 |
2005年 | 36篇 |
2004年 | 33篇 |
2003年 | 14篇 |
2002年 | 21篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有678条查询结果,搜索用时 15 毫秒
631.
Aphrodite Tsaballa Konstantinos Pasentsis Athanasios S. Tsaftaris 《Plant Molecular Biology Reporter》2012,30(3):556-565
Fruit shape is a very important fruit quality character frequently affected by grafting in vegetable plants like pepper. It has already been shown that, similar to tomato, fruit shape in pepper is likely controlled by an Ovate-like gene, CaOvate, the down-regulation of which positively affects fruit elongation. To further understand the molecular mechanisms involved in pepper fruit shape control and the changes imposed by grafting, we have amplified, sequenced, and structurally characterized CaGA20ox1, the target gene of CaOvate, from a long fruit and a round fruit shaped cultivar. The results show that CaGA20ox1 has similar genomic organization to the tomato GA20ox1 and encodes a 375-amino acid polypeptide that shares 89% identity with tomato GA20ox1. We then studied CaGA20ox1 expression in different pepper plant parts and in different developmental stages of flower and fruit development. The expression of the gene was quantified by means of relative quantitative PCR in the developmental stage of 10?days after anthesis fruit of both cultivars. The results showed that there is a significant difference in the expression of the CaGA20ox1 between the two cultivars in this specific stage as well as in the expression of CaGA20ox1 after virus-induced gene silencing (VIGS) of CaOvate. Finally, the 5?? upstream sequences of CaGA20ox1 gene of the two cultivars were examined and compared. These results corroborate our previous findings, where VIGS of CaOvate alters CaGA20ox1 expression, leading to more elongated fruit, and also progress further the understanding of the genes involved in fruit shape control in pepper opening the way for understanding the molecular means of grafting effects. 相似文献
632.
Dimiza F Papadopoulos AN Tangoulis V Psycharis V Raptopoulou CP Kessissoglou DP Psomas G 《Journal of inorganic biochemistry》2012,107(1):54-64
Cobalt(II) complexes with the non-steroidal anti-inflammatory drug naproxen in the presence or absence of nitrogen-donor heterocyclic ligands (pyridine, 2,2′-bipyridine or 1,10-phenanthroline) have been synthesized and characterized with physicochemical and spectroscopic techniques. The deprotonated naproxen acts as monodentate ligand coordinated to Co(II) ion through a carboxylato oxygen. The crystal structure of [bis(aqua)bis(naproxenato)bis(pyridine)cobalt(II)], 2 has been determined by X-ray crystallography. The EPR spectrum of complex 2 in frozen solution reveals that it retains its structure. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that the complexes can bind to CT DNA and [(2,2′-bipyridine)bis(methanol)bis(naproxenato)cobalt(II)] exhibits the highest binding constant to CT DNA. The cyclic voltammograms of the complexes recorded in DMSO solution and in the presence of CT DNA in 1/2 DMSO/buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution have shown that they can bind to CT DNA by the intercalative binding mode which has also been verified by DNA solution viscosity measurements. Competitive study with ethidium bromide (EB) has shown that the complexes can displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB. Naproxen and its cobalt(II) complexes exhibit good binding propensity to human or bovine serum albumin proteins having relatively high binding constant values. The antioxidant activity of the compounds has been evaluated indicating their high scavenging activity against hydroxyl free radicals and superoxide radicals. 相似文献
633.
Bousios A Kourmpetis YA Pavlidis P Minga E Tsaftaris A Darzentas N 《The Plant journal : for cell and molecular biology》2012,69(3):475-488
Sireviruses are one of the three genera of Copia long terminal repeat (LTR) retrotransposons, exclusive to and highly abundant in plants, and with a unique, among retrotransposons, genome structure. Yet, perhaps due to the few references to the Sirevirus origin of some families, compounded by the difficulty in correctly assigning retrotransposon families into genera, Sireviruses have hardly featured in recent research. As a result, analysis at this key level of classification and details of their colonization and impact on plant genomes are currently lacking. Recently, however, it became possible to accurately assign elements from diverse families to this genus in one step, based on highly conserved sequence motifs. Hence, Sirevirus dynamics in the relatively obese maize genome can now be comprehensively studied. Overall, we identified >10 600 intact and approximately 28 000 degenerate Sirevirus elements from a plethora of families, some brought into the genus for the first time. Sireviruses make up approximately 90% of the Copia population and it is the only genus that has successfully infiltrated the genome, possibly by experiencing intense amplification during the last 600 000 years, while being constantly recycled by host mechanisms. They accumulate in chromosome-distal gene-rich areas, where they insert in between gene islands, mainly in preferred zones within their own genomes. Sirevirus LTRs are heavily methylated, while there is evidence for a palindromic consensus target sequence. This work brings Sireviruses in the spotlight, elucidating their lifestyle and history, and suggesting their crucial role in the current genomic make-up of maize, and possibly other plant hosts. 相似文献
634.
Samaras V Piperi C Korkolopoulou P Zisakis A Levidou G Themistocleous MS Boviatsis EI Sakas DE Lea RW Kalofoutis A Patsouris E 《Molecular and cellular biochemistry》2007,304(1-2):343-351
Glioblastoma, (grade IV astrocytoma), is characterized by rapid growth and resistance to treatment. Identification of markers
of aggressiveness in this tumor could represent new therapeutic targets. Interleukins (IL)-6 and IL-10 may be considered as
possible candidates, regulating cell growth, resistance to chemotherapy and angiogenesis. ELISPOT method provides a useful
tool for the determination of the exact cell number of peripheral lymphocytes secreting a specific cytokine. IL-6 and IL-10
secretion levels were determined using ELISPOT methodology in peripheral blood mononuclear cells of 18 patients with astrocytic
neoplasms (3 grade II and 15 grade IV), in parallel with 18 healthy controls. Additionally, immunohistochemical expression
of these two cytokines was performed in paraffin-embedded neoplastic tissue in 12 of these patients. The secretion of IL-6
from peripheral monocytes was significantly higher in glioma patients compared to controls (P = 0.0003). In addition, IL-10 secretion from peripheral mononuclear and tumor cells of glioma patients was also higher as
compared to healthy controls (P = 0.0002). Based on immunohistochemical staining, IL-6 expression was localized in tumor cells and macrophages as well as
in areas of large ischemic necrosis, while the major source of IL-10 expression in glioblastomas was the microglia/macrophage
cells. It is suggested that IL-10 contributes to the progression of astrocytomas by suppressing the patient’s immune response,
whereas IL-6 provides an additional growth advantage. This study demonstrates for the first time the usefulness of ELISPOT
in estimating the secretion of IL-6 and IL-10 from peripheral blood and the correlation of their expression in neoplastic
cells.
Christina Piperi and Penelope Korkolopoulou have equally contributed to this work. 相似文献
635.
636.
Young Kwang Chae Danai Khemasuwan Anastasios Dimou Stefan Neagu Lakshmi Chebrolu Shikha Gupta Alejandra Carpio Jongoh Kim Jeong Hyun Yun Athanasios Smyrlis Alan Friedman William Tester 《PloS one》2014,9(1)
Background
Arterial and venous thrombosis may share common pathophysiology involving the activation of platelets and inflammatory mediators. A growing body of evidence suggests prothrombotic effect of renin angiotensin system (RAS) including vascular inflammation and platelet activation. We hypothesized that the use of angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) plays a role in protecting against venous thromboembolism (VTE) in patients atherosclerosis.Methods
We conducted a retrospective study, reviewing 1,100 consecutive patients admitted to a teaching hospital with a diagnosis of either myocardial infarction or ischemic stroke from 2005 to 2010. Patients who had been treated with anticoagulation therapy before or after the first visit were excluded. The occurrence of VTE during the follow up period, risk factors for VTE on admission, and the use of ACEIs or ARBs during the follow up period were recorded.Results
The mean age of the entire study population was 68.1 years. 52.0% of the patients were female and 76.5% were African American. 67.3% were on RAS inhibitorsThe overall incidence of VTE was 9.7% (n = 107). Among the RAS inhibitor users, the incidence of VTE events was 9.0% (54/603) for the ACEI only users, 7.1% (8/113) for the ARB only users, and 0% (0/24) for the patients taking combination of ACEI and ARB. Among patients on RAS inhibitors, 8.4% (62/740) developed a VTE, compared with 12.5% (45/360) in the nonuser group [HR (hazard ratio), 0.58; 95% CI (confidence interval), 0.39–0.84; P<0.01]. Even after controlling for factors related to VTE (smoking, history of cancer, and immobilization, hormone use) and diabetes, the use of RAS inhibitors was still associated with a significantly lower risk of developing VTE (AHR, 0.59; 95% CI, 0.40–0.88; P = 0.01).Conclusions
The use of RAS inhibitors appears to be associated with a reduction in the risk of VTE. 相似文献637.
George Tsikouris Ioannis Antonopoulos Dionysia Vasdeki Dimosthenis Chrysikos Athanasios Koukakis George Tsakotos Panagiotis Georgakopoulos Theodore Troupis 《Journal of brachial plexus and peripheral nerve injury》2021,16(1):e31
Background The suprascapular notch (SN) represents the point along the route of the suprascapular nerve (SSN) with the greatest potential risk for injury and compression. Thus, factors reducing the area of the notch have been postulated for suprascapular neuropathy development. Methods Thirty-one fresh-frozen shoulders were dissected. The contents of the SN were described according to four types as classified by Polguj et al and the middle-transverse diameter of the notch was measured. Also, the presence of an ossified superior transverse scapular ligament (STSL) was identified. Results The ligament was partially ossified in 8 specimens (25.8%), fully ossified in 6 (19.35%), and not ossified in the remaining 17 (54.85%). The mean middle-transverse diameter of the SN was 9.06 mm (standard deviation [SD] = 3.45). The corresponding for type-I notches was 8.64 mm (SD = 3.34), 8.86 mm (SD = 3.12) was for type-II, and 14.5 mm (SD = 1.02) was for type III. Middle-transverse diameter was shorter when an ossified ligament was present (mean = 5.10 mm, SD = 0.88 mm), comparing with a partially ossified ligament (mean =7.67 mm, SD = 2.24 mm) and a nonossified one (mean = 11.12 mm, SD = 2.92 mm). No statistically significant evidence was found that the middle-transverse diameter depends on the number of the elements, passing below the STSL. Conclusion Our results suggest that SSN compression could be more likely to occur when both suprascapular vessels pass through the notch. Compression of the nerve may also occur when an ossified transverse scapular ligament is present, resulting to significant reduction of the notch''s area. 相似文献
638.
Christina Karpouzi Stefanos Nikolaidis Athanasios Kabasakalis George Tsalis Vassilis Mougios 《Biomarkers》2016,21(3):204-207
Physical exercise can induce oxidative damage in humans. 8-Hydroxy-2′-deoxyguanosine (8-OHdG) is a widely known biomarker of DNA oxidation, which can be determined in blood and urine. The aim of the present study was to compare these two biological fluids in terms of which is more suitable for the estimation of the oxidative damage of DNA by measuring the concentration of 8-OHdG one hour after maximal exercise by enzyme immunoassay. The concentration of 8-OHdG increased with exercise only in plasma (p?<?0.001), and values differed between exercise tests in both plasma and urine (p?<?0.05). In conclusion, plasma appears to be more sensitive to exercise-induced 8-OHdG changes than urine and, hence, a more appropriate medium for assessing oxidative damage of DNA, although the poor repeatability of the measurement needs to be addressed in future studies 相似文献
639.
Reliability of urine lactate as a novel biomarker of lactate production capacity in maximal swimming
Stefanos Nikolaidis Christina Karpouzi George Tsalis Athanasios Kabasakalis Konstantinos G. Papaioannou Vassilis Mougios 《Biomarkers》2016,21(4):328-334
Context: Postexercise urine lactate may be a novel biomarker of lactate production capacity during exercise.Objective: To evaluate the reliability and utility of the urine lactate concentration after maximal swimming trials between different training protocols (6?×?50?m and 3?×?100?m) and training states (active and nonactive swimmers).Materials and methods: Lactate and creatinine were determined by spectrophotometry in blood and urine.Results: Blood and urine lactate concentrations were correlated in-between training protocols and in participants of different training states. The reliability of the urine lactate concentration was moderate for one of the training protocols and good or moderate for the two training states. Additionally, it was lower than that of the blood lactate concentration, and did not improve after normalizing to the urine creatinine concentration.Discussion and conclusion: Although promising as a biomarker of lactate production capacity, urine lactate requires further research to improve its reliability. 相似文献
640.
Georgiadis AN Papavasiliou EC Lourida ES Alamanos Y Kostara C Tselepis AD Drosos AA 《Arthritis research & therapy》2006,8(3):R82
We investigated lipid profiles and lipoprotein modification after immuno-intervention in patients with early rheumatoid arthritis (ERA). Fifty-eight patients with ERA who met the American College of Rheumatology (ACR) criteria were included in the study. These patients had disease durations of less than one year and had not had prior treatment for it. Smokers or patients suffering from diabetes mellitus, hypothyroidism, liver or kidney disease, Cushing's syndrome, obesity, familiar dyslipidemia and those receiving medications affecting lipid metabolism were excluded from the study. Sixty-three healthy volunteers (controls) were also included. Patients were treated with methotrexate and prednisone. Lipid profiles, disease activity for the 28 joint indices score (DAS-28) as well as ACR 50% response criteria were determined for all patients. The mean DAS-28 at disease onset was 5.8 +/- 0.9. After a year of therapy, 53 (91.3%) patients achieved the ACR 20% response criteria, while 45 (77.6%) attained the ACR 50% criteria. In addition, a significant decrease in the DAS-28, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were observed. ERA patients exhibited higher serum levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglycerides, whereas their serum high-density lipoprotein cholesterol (HDL-C) levels were significantly lower compared to controls. As a consequence, the atherogenic ratio of TC/HDL-C as well as that of LDL-C/HDL-C was significantly higher in ERA patients compared to controls. After treatment, a significant reduction of the atherogenic ratio of TC/HDL-C as well as that of LDL-C/HDL-C was observed, a phenomenon primarily due to the increase of serum HDL-C levels. These changes were inversely correlated with laboratory changes, especially CRP and ESR. In conclusion, ERA patients are characterized by an atherogenic lipid profile, which improves after therapy. Thus, early immuno-intervention to control disease activity may reduce the risk of the atherosclerotic process and cardiovascular events in ERA patients. 相似文献