全文获取类型
收费全文 | 702篇 |
免费 | 37篇 |
国内免费 | 2篇 |
出版年
2023年 | 6篇 |
2022年 | 26篇 |
2021年 | 54篇 |
2020年 | 21篇 |
2019年 | 33篇 |
2018年 | 32篇 |
2017年 | 24篇 |
2016年 | 33篇 |
2015年 | 36篇 |
2014年 | 42篇 |
2013年 | 41篇 |
2012年 | 39篇 |
2011年 | 48篇 |
2010年 | 27篇 |
2009年 | 17篇 |
2008年 | 35篇 |
2007年 | 32篇 |
2006年 | 27篇 |
2005年 | 33篇 |
2004年 | 21篇 |
2003年 | 17篇 |
2002年 | 16篇 |
2001年 | 15篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 3篇 |
1967年 | 4篇 |
1966年 | 1篇 |
1933年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有741条查询结果,搜索用时 15 毫秒
11.
Elicitor-induced hydroxycinnamoyl-CoA:tyramine hydroxycinnamoyltransferase in plant cell suspension cultures 总被引:4,自引:0,他引:4
Treatment of Nicotiana glutinosa L. cell suspension cultures with chitosan results in the co-induction of phenylalanine ammonia lyase, 4-eoumarate:CoA ligase, tyrosine decarboxylase and tyramine hydroxycinnamoyltransferase, all involved in the biosynthesis of hydroxycinnamoyltyramines. The highest enzyme activities were observed around 12 h after addition of 0.8 to 1 mg chitosan per g fresh weight of cells. No hydroxycinnamoyltyramines could be detected by TLC or HPLC of extracts made from non-treated or elicited cells. [14 C]-Tyramine was incorporated into insoluble polymeric material at a higher rate in elicitor-treated than in non-treated cells of N. glutinosa. Tyramine hydroxycinnamoyltransferase could be induced in suspension cultured cells of Eschscholtzia califortnca Cham, but not in cells of Phaseolus vulgaris L. or Catharanthus roseus (L.) G. Don by addition of a yeast elicitor to the growth medium. 相似文献
12.
Marian L. Kruzel Jeffrey K. Actor Michał Zimecki Jasen Wise Paulina Płoszaj Shaper Mirza Mark Kruzel Shen-An Hwang Xueqing Ba Istvan Boldogh 《Journal of biotechnology》2013
Lactoferrin, an iron-binding protein found in high concentrations in mammalian exocrine secretions, is an important component of the host defense system. It is also a major protein of the secondary granules of neutrophils from which is released upon activation. Due to its potential clinical utility, recombinant human lactoferrin (rhLF) has been produced in various eukaryotic expression systems; however, none of these are fully compatible with humans. Most of the biopharmaceuticals approved by the FDA for use in humans are produced in mammalian expression systems. The Chinese hamster ovary cells (CHO) have become the system of choice for proteins that require post-translational modifications, such as glycoproteins. 相似文献
13.
Aysegul Gorur Senay Balci Fidanci Nil Dogruer Unal Lokman Ayaz Serin Akbayir Hatice Yildirim Yaroglu Musa Dirlik Mehmet Sami Serin Lulufer Tamer 《Molecular biology reports》2013,40(3):2091-2096
Gastric cancer is the fourth most prevalent malignancy worldwide and remains the second most common cause of cancer-related death globally. Understanding the molecular structure of gastric carcinogenesis might identify new diagnostic and therapeutic strategies for this disease. Thus, early detection of gastric cancer is a key measure to reduce the mortality and improve the prognosis of gastric cancer. There have recently been several reports that microRNAs (miRNAs) circulate in highly stable, cell-free forms in blood. Because serum and plasma miRNAs are relatively easy to access, circulating miRNAs also have great potential to serve as non-invasive biomarkers. Although a number of miRNAs associated with gastric cancer have been identified, the underlying mechanism of these miRNAs in tumorigenesis and tumor progression remains to be investigated. The purpose of this study is to identify the potential of serum miRNAs as biomarkers for early detection of gastric cancer patients. RNA was isolated using the High Pure miRNA Isolation Kit (Roche) following the manufacturer’s protocol. cDNA and preamplification protocols were obtained from the isolated plasma miRNAs. The BioMark? 96.96 Dynamic Array (Fluidigm Corporation) for real-time qPCR was used to simultaneously quantite the expression of 740 miRNAs. All statistical analyses were performed using the Biogazelle’s qbase PLUS 2.0 software. In this study, among 740 miRNAs that we analyzed only miR-195-5p was significantly (p < 0.05, fold changes = 13, 3) down-regulated in gastric cancer patients compared with control. We demonstrated that miR-195-5p is a novel tumor suppressor miRNA and may contribute to gastric carcinogenesis. The miRNA expression profile described in this study should contribute to future studies on the role of miRNAs in gastric cancer. 相似文献
14.
Farrukh Baig Mirza John S. Gray 《Journal of experimental marine biology and ecology》1981,54(2):181-207
The macrobenthic fauna of the organically enriched Oslofjord was sampled in Sept.–Nov. 1977. Seventy-six stations were sampled using a stratified random plan. A total of 146 species were identified, dominated by polychaetes, molluscs and echinoderms. The faunal data were analysed by a variety of methods including diversity indices, log-normal distribution of individuals among species, factor analysis and numerical classification. The primary aim was the detection of pollution-induced disturbance and to delimit the extent of pollution on the benthic fauna of Oslofjord. All of the methods used showed a gradient from heavy pollution at the innermost part of the fjord where few species occurred, together with high dominance and low diversity, to normal unpolluted conditions at the Drøbak sill with high species diversity. From the classification analysis a combination of both site and species data revealed a trend in species groupings which were broadly similar to data from other Scandinavian fjords and from Scotland. Hydrographical and biological data taken at the turn of the century and in the 1960's compared with the present data show declining conditions in Oslofjord, due primarily to organic enrichment combined with a naturally poor water exchange which leads to stagnation of the water mass. 相似文献
15.
Md. Rezwan Molla Md. Motiar Rohman Mahmuda Binte Monsur Mirza Hasanuzzaman Lutful Hassan 《Phyton》2021,90(5):1425-1443
This study was undertaken to investigate oxidative stress tolerant mechanisms in chilli (Capsicum annuum L.)
under drought genotypes through evaluating morphological, physiological, biochemical and stomatal parameters.
Twenty genotypes were evaluated for their genetic potential to drought stress tolerant at seedling stage. Thirty
days old seedlings were exposed to drought stress induced by stop watering for the following 10 days and rewatering for the following one week as recovery. Based on their survival performance, two tolerant genotypes
viz. BD-10906 and BD-109012 and two susceptible genotypes viz. BD-10902 and RT-20 were selected for studying
the oxidative stress tolerance mechanism. Drought reduced root and shoot length, dry weight, ratio, petiole weight
and leaf area in both tolerant and susceptible genotypes, and a higher reduction was observed in susceptible genotypes. Lower reduction of leaf area and photosynthetic pigments were also found in tolerant genotypes. Moreover,
tolerant genotypes showed higher recovery than susceptible genotypes after the removal of stress. A higher reduction
of relative water content (RWC) may cause an imbalance between absorbed and transpirated water in susceptible
genotypes. Higher accumulation of proline in tolerant genotypes might be helpful to for better osmotic maintenance
than that in susceptible genotypes. Tolerant genotypes showed higher antioxidant activity as they showed DPPH
radical scavenging percentage than the susceptible genotypes. Moreover, closer stomata in tolerant genotypes than
susceptible ones helped to avoid dehydration in tolerant genotypes. Thus, the above morphological, physiological,
biochemical and stomatal parameters helped to show better tolerance in chilli under drought stress. 相似文献
16.
17.
Hunter Elena Percival Benita Ahmad Zeeshan Chang Ming-Wei Hunt John A. Tasker Séverine De Risio Luisa Wilson Philippe B. 《Molecular and cellular biochemistry》2021,476(11):4133-4137
Molecular and Cellular Biochemistry - Chronic kidney disease (CKD) is a renal dysfunction that can lead to high rates of mortality and morbidity, particularly when coupled with late diagnosis. CKD... 相似文献
18.
Energy consumption and CO2 emissions have been increasing continuously over the past few decades in China and there is a pressing need to replace the fossil fuel‐based economy with an efficient low‐carbon system, tailor‐made to future requirements. China is starting an energy transition with the aim of building an energy system for the future. China has made tremendous progress in increasing the amount of renewable energy and reducing the cost of renewable energy over the last 20 years. According to the 14th 5 year plan, China aims to incorporate 20% of renewable energy to the primary energy mix and attain 27% reduction in CO2 emissions. Bioenergy crops constitute a significant proportion of biomass‐based bioenergy and have recently been promoted by the Chinese Government to help overcome food and fuel conflict. Steps are being taken to promote bioenergy crops on marginal lands in China, and various regions across the country with soil marginality have been evaluated for bioenergy crop cultivation. The present paper reviews the status of bioenergy in China and the potential status of marginal lands from different regions of China. It also elaborates on some of the policies, subsidies and incentives allocated by the Chinese Government for the promotion of biomass‐based energy. Land management and plant improvement strategies were discussed, which are effective in making marginal lands suitable for bioenergy crop cultivation. Managing planting strategies, intercropping and crop rotation are effective management practices used in China for the utilization of marginal lands. A national investigation is desirable for creating an inventory of technical and economic potential of biomass feedstocks that could be planted on marginal lands. This would assist with highlighting the pros and cons of using marginal lands for bioenergy production and effective policy making. 相似文献
19.
Bashir Ahmad Ali Muhammad Yousafzai Ayaz Ali Khan Mohammad Attaullah Waqar Ali Saeed Ahmad Ghazala Yasmin Zamani Farhat Naz Sumayya Raziq Amjad Ali 《Saudi Journal of Biological Sciences》2021,28(8):4324-4328
Present study focuses on ameliorative potential of Typha elephantina leave’s aqueous (TE.AQ) extract against Paracetamol (PCM) induced toxicity in rabbits. We fed the male rabbits with 300 mg PCM in alone and in combination with TE.AQ at different doses i.e. (100, 200 and 300 mg/kg body weight) or silymarin (100 mg/kg) daily for 21 days. PCM in alone significantly (P < 0.5) increased serum urea, uric acid, creatinine, total protein, albumin, globulin and blood urea nitrogen. Serum sodium, potassium and magnesium level were high. The glutathione, radical scavenging activity and Thiobarbituric acid reactive substances were significantly reduced. Treatment with TE.AQ at dose rate 300 mg/kg body weight and Silymarin significantly ameliorated all the parameters when compared with PCM administered group. The 100 and 200 mg of TE.AQ showed no significant effects. The histopathological examination confirmed the therapeutic potential of TE.AQ. These results established the presence of natural antioxidants in Typha elephantina leaves. 相似文献
20.
Atherosclerosis is a chronic inflammatory disease arising due to an imbalance in lipid metabolism and maladaptive immune response driven by the accumulation of cholesterol-laden macrophages in the artery wall. Interactions between monocytes/macrophages and endothelial cells play an essential role in the pathogenesis of atherosclerosis. In our current study, nitric oxide synthase 1 (NOS1)-derived nitric oxide (NO) has been identified as a regulator of macrophage and endothelial cell interaction. Oxidized LDL (OxLDL) activates NOS1, which results in the expression of CD40 ligand in macrophages. OxLDL-stimulated macrophages produce some soluble factors which increase the CD40 receptor expression in endothelial cells. This increases the interaction between the macrophages and endothelial cells, which leads to an increase in the inflammatory response. Inhibition of NOS1-derived NO might serve as an effective strategy to reduce foam cell formation and limit the extent of atherosclerotic plaque expansion. 相似文献