全文获取类型
收费全文 | 386篇 |
免费 | 39篇 |
国内免费 | 1篇 |
专业分类
426篇 |
出版年
2023年 | 2篇 |
2021年 | 4篇 |
2020年 | 17篇 |
2019年 | 40篇 |
2018年 | 32篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 22篇 |
2012年 | 5篇 |
2010年 | 10篇 |
2009年 | 6篇 |
2008年 | 12篇 |
2007年 | 15篇 |
2006年 | 17篇 |
2005年 | 10篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 9篇 |
2001年 | 16篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 18篇 |
1997年 | 7篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 5篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 13篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1957年 | 2篇 |
1956年 | 1篇 |
1954年 | 2篇 |
1953年 | 4篇 |
1952年 | 2篇 |
1930年 | 1篇 |
1923年 | 1篇 |
排序方式: 共有426条查询结果,搜索用时 15 毫秒
131.
Özgür Yiğiter MD Ali Cagdas Yorukoglu MD Nilay Şentürk MD Yavuz Dodurga MD Ahmet Fahir Demirkan MD 《Journal of cellular biochemistry》2019,120(7):11525-11530
The aim of this study is to investigate the effects of type I collagen on bone defects and on genes specifically for osteogenesis in a rat model. Two millimeter drill hole bone defect was created in the femur of rats. In the experimental group, type I collagen was applied in bone defects whereas in control group defects were left empty. Inflammation, development of connective tissue, osteogenesis, and foreign body reaction parameters evaluated with histologically and genes evaluated by blood samples. In the experimental group, the histopathologically significant change was found in favor of bone healing only at the first week. A significant increase was found in genetic expressions of BMP-1, 2, 3, 4, 5, 6, 7, TGF-βRII, Smad-1, IL-6, BMPR-IA, BMPR-IB, Eng, BMPR-II, c-fos, Cdkn1a, Chrd, Gdf-5, Id-1, PDGF-β, IGF-1, Serpine-1, and TGF-βRI at the first hour. At the first, third, and sixth week, no significant increase was found in any of the gene expressions. Type I collagen is found to be effective in favor of bone healing through increased inflammatory cytokines and expression of BMP genes in the early stages of fracture healing. 相似文献
132.
Peizhong Zheng MD Ali Babar Seshasai Parthasarathy Ryan Gibson Kelly Parliament Josh Flook Thomas Patterson Peter Friedemann Siva Kumpatla Steve Thompson 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2014,127(7):1537-1547
Key message
We identified a G-nucleotide insertion in a maize FatB responsible for reducing saturated fatty acids through QTL mapping and map-based cloning and developed an allele-specific DNA marker for molecular breeding.Abstract
Vegetable oils with reduced saturated fatty acids have signficant health benefits. SRS72NE, a Dow AgroSciences proprietory maize inbred line, was found to contain signficantly reduced levels of palmitic acid and total saturated fatty acids in seed oil when compared to other common inbreds. Using F2 and F3 populations derived from a cross between SRS72NE and a normal inbred SLN74, we have demonstrated that the reduced saturated fatty acid phenotype in SRS72NE is controlled by a single QTL on chromosome 9 that explains 79.1 % of palmitic acid and 79.6 % total saturated fatty acid variations. The QTL was mapped to an interval of 105 kb that contains one single gene, a type B fatty acyl-ACP thioesterase (ZmFatB; GRMZM5G829544). ZmFatB alleles from SRS72NE and common inbreds were cloned and sequenced. SRS72NE fatb allele contains a single nucleotide (G) insertion in the 6th exon, which creates a premature stop codon 22 base pairs down stream. As a result, ZmFatB protein from SRS72NE is predicted to contain eight altered and 90 deleted amino acids at its C-terminus. Because the affected region is part of the conserved acyl-ACP thioesterase catalytic domain, the truncated ZmFatB in SRS72NE is likely non-functional. We also show that fatb RNA level in SRS72NE is reduced by 4.4-fold when compared to the normal allele SNL74. A high throughput DNA assay capable of differentiating the normal and reduced saturate fatty acid alleles has been developed and can be used for accelerated molecular breeding. 相似文献133.
134.
Akbar SM Sharma HC Jayalakshmi SK Sreeramulu K 《Journal of bioenergetics and biomembranes》2012,44(1):233-241
The cotton bollworm, Helicoverpa armigera is a polyphagous pest in Asia, Africa, and the Mediterranean Europe. Salicylic acid (SA) and jasmonic acid (JA) are the cell
signaling molecules produced in response to insect attack in plants. The effect of these signaling molecules was investigated
on the oxidative phosphorylation and oxidative stress of H. armigera. SA significantly inhibited the state III and state IV respiration, respiratory control index (RCI), respiratory complexes
I and II, induced mitochondrial swelling, and cytochrome c release in vitro. Under in vivo conditions, SA induced state IV
respiration as well as oxidative stress in time- and dose-dependent manner, and also inhibited the larval growth. In contrast,
JA did not affect the mitochondrial respiration and oxidative stress. SA affected the growth and development of H. armigera, in addition to its function as signaling molecules involved in both local defense reactions at feeding sites and the induction
of systemic acquired resistance in plants. 相似文献
135.
J Roberto TRUJILLO Gilberto JARAMILLO-RANGEL Marta ORTEGA-MARTINEZ Augusto C PENALVA de OLIVEIRA Jose E VIDAL Joseph BRYANT Robert C GALLO 《Cell research》2005,(Z1)
INTRODUCTION AND NEUROEPIDEMIO- LOGY OF HIV/AIDS AIDS was first recognized as a new and distinct clini- cal entity in 1981 [1] and the HIV-1 as their casual agent in 1983 [2]. Since then, the HIV/AIDS epidemic has reached epidemic proportions with a total accumulative number of more than 60 million people, according to the Joint United Nations Programme on HIV/AIDS (UNAIDS) and WHO. The extensive spread of HIV-1 epidemics in Asia was not appreciated in the 1980s,… 相似文献
136.
siRNA, miRNA and HIV: promises and challenges 总被引:2,自引:0,他引:2
INTRODUCTION The recent discovery of small interfering RNA (siRNA) revealed an important role for small RNAs in regulating gene expression. First described in plants, as “post- trancriptional gene silencing” (PTGS) [1], RNA interfer- ence (RNAi) is a nucleic-acid based immune defense against viruses, transgenes and transposons [2]. Triggered by double-stranded RNA (dsRNA), RNAi leads to the se- quence specific degradation of a target mRNA [3]. In eukaryotic cells, long dsRN… 相似文献
137.
David J.A. Jenkins MD Andrea R. Josse Joseph Beyene Paul Dorian Michael L. Burr Roxanne LaBelle Cyril W.C. Kendall Stephen C. Cunnane 《CMAJ》2008,178(2):157-164
Background
A recent Cochrane meta-analysis did not confirm the benefits of fish and fish oil in the secondary prevention of cardiac death and myocardial infarction. We performed a meta-analysis of randomized controlled trials that examined the effect of fish-oil supplementation on ventricular fibrillation and ventricular tachycardia to determine the overall effect and to assess whether heterogeneity exists between trials.Methods
We searched electronic databases (MEDLINE, EMBASE, The Cochrane Central Register of Controlled Trials, CINAHL) from inception to May 2007. We included randomized controlled trials of fish-oil supplementation on ventricular fibrillation or ventricular tachycardia in patients with implantable cardioverter defibrillators. The primary outcome was implantable cardioverter defibrillator discharge. We calculated relative risk [RR] for outcomes at 1-year follow-up for each study. We used the DerSimonian and Laird random-effects methods when there was significant heterogeneity between trials and the Mantel-Hanzel fixed-effects method when heterogeneity was negligible.Results
We identified 3 trials of 1–2 years'' duration. These trials included a total of 573 patients who received fish oil and 575 patients who received a control. Meta-analysis of data collected at 1 year showed no overall effect of fish oil on the relative risk of implantable cardioverter defibrillator discharge. There was significant heterogeneity between trials. The second largest study showed a significant benefit of fish oil (relative risk [RR] 0.74, 95% confidence interval [CI] 0.56–0.98). The smallest showed an adverse tendency at 1 year (RR 1.23, 95% CI 0.92–1.65) and significantly worse outcome at 2 years among patients with ventricular tachycardia at study entry (log rank p = 0.007).Conclusion
These data indicate that there is heterogeneity in the response of patients to fish-oil supplementation. Caution should be used when prescribing fish-oil supplementation for patients with ventricular tachycardia.There is a public perception that fish and fish oil can be recommended uniformly for the prevention of coronary artery disease.1–3 However, the scientific evidence is divided4,5 and official agencies have called for more research.6It is estimated that 0.5% of patients with coronary heart disease, 1% of patients with diabetes or hypertension and 2% of the general population at low risk of coronary heart disease take fish-oil supplements.7 In 2004, the price of fish oils overtook that of vegetable oils, and in 2006, the price rose to US$750 per ton.8 The value of fish oil as a nutraceutical in the European market was US$194 million in 2004, and it is anticipated that the price will continue to rise as availability declines.8 Canada is both a consumer and an exporter of fish oil, and it exported 15 000 tons in 2006.9The scientific debate over the clinical value of fish oil is highlighted by a recent Cochrane review, which concluded that long-chain omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid) had no clear effect on total mortality, combined cardiovascular events or cancer.4 Furthermore, another recent meta-analysis10 only showed a significant positive association between fish-oil consumption and prevention of restenosis after coronary angioplasty in a select subgroup after excluding key negative papers.11 Finally, the antiarrhythmic effect, which is proposed to be the principal mechanism of their benefit in cardiovascular disease, has not been demonstrated clearly in clinical trials.12–14We therefore performed a meta-analysis of randomized controlled trials that examined the effect of fish-oil supplementation in patients with implantable cardioverter defibrillators who are at risk of ventricular arrhythmia to determine the overall effect of fish oils. We also sought to investigate whether there was significant heterogeneity between trials. 相似文献138.
139.
W Virgil Brown MD 《Trials》2001,2(1):12-4
Arteriosclerotic vascular disease manifests as heart disease, stroke, aortic aneurysms, and peripheral vascular disease, and is a growing problem world-wide. The preventive efforts made so far have demonstrated that lowering LDL-C is one action that individuals and populations can do with significant success in delaying the onset of clinical events. Epidemiological studies and small clinical trials suggest that more aggressive and sustained lowering to LDL-C below 100 mg/dl could result in 50 to 70% reductions in vascular death. The full benefit of reducing LDL-C is only now being tested in adequate clinical trials. 相似文献
140.