全文获取类型
收费全文 | 647篇 |
免费 | 57篇 |
国内免费 | 2篇 |
专业分类
706篇 |
出版年
2023年 | 10篇 |
2022年 | 29篇 |
2021年 | 57篇 |
2020年 | 37篇 |
2019年 | 73篇 |
2018年 | 60篇 |
2017年 | 26篇 |
2016年 | 36篇 |
2015年 | 29篇 |
2014年 | 39篇 |
2013年 | 43篇 |
2012年 | 32篇 |
2011年 | 43篇 |
2010年 | 20篇 |
2009年 | 19篇 |
2008年 | 21篇 |
2007年 | 27篇 |
2006年 | 14篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 3篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1962年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有706条查询结果,搜索用时 15 毫秒
91.
92.
93.
Chondrogenic differentiation of human scalp adipose‐derived stem cells in Polycaprolactone scaffold and using Freeze Thaw Freeze method 下载免费PDF全文
94.
Molecular dynamics study of biodegradation of azo dyes via their interactions with AzrC azoreductase
Hamed Haghshenas Maryam Kay Fariba Dehghanian 《Journal of biomolecular structure & dynamics》2016,34(3):453-462
Azo dyes are one of the most important class of dyes, which have been widely used in industries. Because of the environmental pollution of azo dyes, many studies have been performed to study their biodegradation using bacterial systems. In present work, the AzrC of mesophilic gram-positive Bacillus sp. B29 has been considered to study its interaction with five common azo dyes (orange G, acid red 88, Sudan I, orange I, and methyl red). The molecular dynamics simulations have been employed to study the interaction between AzrC and azo dyes. The trajectory was confirmed using root mean square deviation and the root mean square fluctuation analyses. Then, the hydrogen bond and alanine scanning analyses were performed to reveal active site residues. Phe105 (A), Phe125 (B), Phe172 (B), and Pro132 (B) have been found as the most important hydrophobic residues whereas Asn104 (A), Tyr127 (B), and Asn187 (A) have key role in making hydrogen bond. The results of molecular mechanics Poisson–Boltzmann surface area and molecular mechanics generalized Born surface area calculations proved that the hydrophobic azo dyes like Acid red 88 binds more tightly to the AzrC protein. The calculated data suggested MR A 121 (B) I as a potential candidate for improving the AzrC–MR interactions. 相似文献
95.
Hamed A. El-Serehy Khaled A. Al-Rasheid Fahad A. Al-Misned Abdul Allah R. Al-Talasat Mohamed M. Gewik 《Saudi Journal of Biological Sciences》2016,23(3):327-334
Population density and biomass of bacteria and meiofauna were investigated seasonally in the sediments of the north-western bank of Red Sea. Samples of sediments were collected seasonally from three different stations to determine microphytobenthic biomass (chlorophyll a), protein, lipid, carbohydrate, and total organic matter concentrations. These investigations revealed that microbial components tended to increase their dominancy, whereas sensitive meiofauna were extremely reduced during the entire study period. Thus a very low density of the total meiofauna (with an annual average of 109 ± 26 ind./10 cm2) was recorded whilst the benthic microbial population densities exhibited higher values (ranging from 0.31 ± 0.02 × 108 to 43.67 ± 18.62 × 108/g dry sediment). These changes in the relative importance analysis of benthic microbial components versus meiofaunal ones seem to be based on the impact of organic matter accumulation on the function and structure of these benthic communities. Proteins, lipids and carbohydrates showed very low concentration values, and the organic matter mostly consisted of carbohydrates, reflecting lower nutritional values for benthic fauna in general and meiofauna in particular. The distribution of microbial and meiofaunal communities seems to be dependent on the quality of the organic matter rather than on its quantity. Total organic matter concentrations varied between 5.8 and 7.6 mg/g, with organic carbon accounting for only 32% of the total organic matter. Chlorophyll a attained very low values, fluctuating between 0.11 and 0.56 μg/g, indicating the oligotrophy of the studied area. The very low concentration of chlorophyll a in the Red Sea sediment suggests that the sedimentary organic matter, heterotrophic bacteria and/or protozoa constitute an alternative resource that is consumed by meiofauna when algae are less abundant. Protozoa, therefore, represent the “missing link in bacteria–meiofauna interaction in the Red Sea marine sediment ecosystem. 相似文献
96.
97.
98.
Hamed Alborzinia Marjan Shaikhkarami Peter Hortschansky Stefan Wölfl 《Traffic (Copenhagen, Denmark)》2016,17(9):1042-1053
Morphogen gradients and concentration are critical features during early embryonic development and cellular differentiation. Previously we reported the preparation of biologically active, fluorescently labeled BMP2 and quantitatively analyzed their binding to the cell surface and followed BMP2 endocytosis over time on the level of single endosomes. Here we show that this internalized BMP2 can be transferred to neighboring cells and, moreover, also activates downstream BMP signaling in adjacent cells, indicated by Smad1/5/8 phosphorylation and activation of the downstream target gene id1. Using a 3D matrix to modulate cell–cell contacts in culture we could show that direct cell–cell contact significantly increased BMP2 transfer. Using inhibitors of vesicular transport, transfer was strongly inhibited. Interestingly, cotreatment with the physiological BMP inhibitor Noggin increased BMP2 uptake and transfer, albeit activation of Smad signaling in neighboring cells was completely suppressed. Our findings present a novel and interesting mechanism by which morphogens such as BMP2 can be transferred between cells and how this is modulated by BMP antagonists such as Noggin, and how this influences activation of Smad signaling by BMP2 in neighboring cells. 相似文献
99.
Payabvash S Ghahremani MH Goliaei A Mandegary A Shafaroodi H Amanlou M Dehpour AR 《Free radical biology & medicine》2006,41(12):1817-1828
Nitric oxide is known to modulate intracellular glutathione levels, but the relationship between nitric oxide synthesis and glutathione metabolism during endotoxemia is unknown. The present study was designed to examine the effects of increased nitric oxide formation on hepatic glutathione synthesis and antioxidant defense in endotoxemic mice. Our results demonstrate that hepatic glutathione synthesis is decreased for 24 h following injection of lipopolysaccharide (LPS). Administration of the cysteine precursor, L-2-oxothiazolidine-4-carboxylic acid (OTZ), failed to normalize hepatic glutathione concentration, and suggests that decreased γ-glutamylcysteine ligase activity is primarily responsible for the decrease in hepatic glutathione levels during endotoxemia. Inhibition of nitric oxide synthesis prevented the endotoxin-induced changes in hepatic and plasma glutathione status and up-regulated liver glutathione and cysteine synthesis pathways at the level of gene expression. Furthermore, whereas the activity of glutathione peroxidase and glutathione S-transferase decreased during endotoxemia, both of these changes were prevented by inhibition of nitric oxide synthesis. In conclusion, increased nitric oxide synthesis during endotoxemia causes marked changes in glutathione flux and defenses against oxidative stress in the liver. 相似文献
100.
In the present study, we compared the response to salinity of three plants from Brittany coast with contrasted ecological status: Limonium latifolium (salt marshes), Matricaria maritima (beach tops and sand dunes) and Crambe maritima (fixed dunes). Under controlled glasshouse conditions, the growth of the three plants decreased with increasing external salinity. L. latifolium and C. maritima exhibited the highest and lowest resistance to severe salt stress (400 mM), respectively. M. maritima could be considered as an intermediate species, since it tolerated salinity up to 200 mM. The same observation could be made with sodium absorption and acuumulation in plant tissues, the most tolerant species (L. latifolium being the least Na accumulator. Hydrogen peroxide (H2O2) and malondialdehyde (MDA), commonly produced in conditions of stress, accumulated significantly in salt treated C. maritima and M. maritima while not in the tolerant L. latifolium. The latter used glutathione reductase to maintain constant H2O2 levels under salt stress while peroxidases were very low and ascorbate peroxidase did not respond to salinity stimulation. The medium tolerant halophyte M. maritima used peroxidases to protect from NaCl-induced H2O2, while the sensitive C. maritima failed to detoxify H2O2 despite a sharp increase in catalase activity. Results showed that the three coastal species differ in resistance to salinity. They also suggested that the level of plant resistance to salinity could be attributed to differing mechanisms to manage the accumulation of sodium and cope with the oxidative damages. 相似文献