全文获取类型
收费全文 | 346篇 |
免费 | 38篇 |
出版年
2021年 | 3篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 17篇 |
2012年 | 13篇 |
2011年 | 16篇 |
2010年 | 14篇 |
2009年 | 8篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 17篇 |
2005年 | 9篇 |
2004年 | 18篇 |
2003年 | 15篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1973年 | 4篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1965年 | 4篇 |
1964年 | 2篇 |
1959年 | 2篇 |
1909年 | 2篇 |
排序方式: 共有384条查询结果,搜索用时 140 毫秒
51.
52.
Effect of Shaking Speed on the Secretion of Enterotoxin B by Staphylococcus aureus 总被引:10,自引:4,他引:6
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The concentration of enterotoxin B secreted by four strains of Staphylococcus aureus was dependent upon the shaking speed. For the conditions established, each strain demonstrated an optimal shaking speed, and speeds in excess of the optimum resulted in decreased secretion of toxin. At the optimal shaking speed, maximum secretion occurred at 37 C. At 45 C, both growth and toxin secretion were absent. By using agar containing antienterotoxin B sera, studies with strain S-6 at optimal and suboptimal shaking speeds demonstrated that individual cells vary in their toxin-synthesizing ability and that the relative numbers of high and low producers change during the growth cycle. Although most of the toxin was secreted during the first 12 hr of growth, a portion was secreted during the subsequent 6 hr, even though growth as measured by colony-forming units per milliliter decreased and Klett units increased. 相似文献
53.
Antisera from rabbits that had been immunized with a highly active membrane preparation of (Na+ + K+)-ATPase from the outer medulla of pig kidney strongly inhibited (Na+ + K+)-ATPase activity in various tissues. When the antiserum was incorporated into released human red cell ghosts, the ouabain-sensitive efflux of Na+ into both 15 mM K+ and K+-free high Na+ media was completely abolished. This effect was not observed when non-immune serum was used, or when the immune serum was allowed access only to the outer surface of the red cell membranes. 相似文献
54.
A commercial enzyme preparation, originally obtained from a Flavobacterium(Cytophaga), was fractionated by continuous electrophoresis, giving a protein fraction which hydrolysed laminarin, carboxymethylpachyman, barley β-glucan, lichenin and cellodextrin in random fashion. This enzymic activity was not very stable. Ion-exchange chromatography and molecular-sieve chromatography on Bio-Gel P-60 showed that this activity was due to two specific β-glucanases, an endo-β-(1→3)-glucanase and an endo-β-(1→4)-glucanase. The two enzymes occur in both high- and low-molecular-weight forms, the latter endo-β-(1→3)-glucanase having a molecular weight of about 16000. 相似文献
55.
The purpose of this study was to investigate if the intestinal absorption of copper in drinking water is altered in the presence of complexing agents from a fulvic acid mixture and an infant formula powder. Ten to twelve day old rat pups were given a single oral dose of radio-labeled Cu in deionized water (0.93 mg Cu/l), in water containing fulvic acids (10 mg/l), in infant formula mixed with deionized water, or in infant formula mixed with water containing fulvic acids. Six hours after dosage, radioactive Cu was analyzed in the mucosa of the small intestine, the liver and the remaining carcass (excluding the liver and gastrointestinal tract) by gamma counting. Dialysis and centrifugation experiments showed that Cu was complexed by components in the fulvic acid and formula mixtures, although the presence of fulvic acids in the water did not alter the Cu fractionation in the formula. The fractional Cu uptake (% of dose) from the intestinal lumen to the mucosa was not markedly changed by the presence of the chelating agents. However, the retention of Cu in the intestinal mucosa was increased by both fulvic acids and formula. Concomitantly, the absorption rate of Cd to the circulatory system was decreased. No interactive effect between fulvic acids and formula was found on the Cu absorption. These findings indicate that the water quality may be an important determinant of the rate of intestinal Cu absorption from drinking water. Moreover, in the future risk assessment of copper in drinking water, the possibility of alterations in absorption of drinking-water Cu has to be considered when the drinking water is used for cooking. 相似文献
56.
The invasive freshwater snail Tarebia granifera (Lamarck, 1822) was first reported in South Africa in 1999 and it has become widespread across the country, with some evidence to suggest that it reduces benthic macroinvertebrate biodiversity. The current study aimed to identify the primary abiotic drivers behind abundance patterns of T. granifera, by comparing the current abundance of the snail in three different regions, and at three depths, of the highly modified Nseleni River in KwaZulu-Natal, South Africa. Tarebia granifera was well established throughout the Nseleni River system, with an overall preference for shallow waters and seasonal temporal patterns of abundance. Although it is uncertain what the ecological impacts of the snail in this system are, its high abundances suggest that it should be controlled where possible and prevented from invading other systems in the region. 相似文献
57.
Yang Y Glynn JM Olson BJ Schmitz AJ Osteryoung KW 《Current opinion in plant biology》2008,11(6):577-584
Plastid division is executed by the coordinated action of at least two molecular machineries--an internal machinery situated on the stromal side of the inner envelope membrane that was contributed by the cyanobacterial endosymbiont from which plastids evolved, and an external machinery situated on the cytosolic side of the outer envelope membrane that was contributed by the host. Here we review progress in defining the components of the plastid division complex and understanding the mechanisms of envelope constriction and division-site placement in plants. We also highlight recent work identifying the first molecular linkage between the internal and external division machineries, shedding light on how their mid-plastid positioning is coordinated across the envelope membranes. Little is known about the mechanisms that regulate plastid division in plant cells, but recent studies have begun to hint at potential mechanisms. 相似文献
58.
Summary . The Wilcoxon Mann-Whitney (WMW) U test is commonly used in nonparametric two-group comparisons when the normality of the underlying distribution is questionable. There has been some previous work on estimating power based on this procedure ( Lehmann, 1998 , Nonparametrics ). In this article, we present an approach for estimating type II error, which is applicable to any continuous distribution, and also extend the approach to handle grouped continuous data allowing for ties. We apply these results to obtaining standard errors of the area under the receiver operating characteristic curve (AUROC) for risk-prediction rules under H 1 and for comparing AUROC between competing risk prediction rules applied to the same data set. These results are based on SAS -callable functions to evaluate the bivariate normal integral and are thus easily implemented with standard software. 相似文献
59.
Jonathan M. Glynn Yue Yang Stanislav Vitha Aaron J. Schmitz Mia Hemmes Shin-ya Miyagishima Katherine W. Osteryoung 《The Plant journal : for cell and molecular biology》2009,59(5):700-711
Chloroplast division in plant cells is accomplished through the coordinated action of the tubulin-like FtsZ ring inside the organelle and the dynamin-like ARC5 ring outside the organelle. This coordination is facilitated by ARC6, an inner envelope protein required for both assembly of FtsZ and recruitment of ARC5. Recently, we showed that ARC6 specifies the mid-plastid positioning of the outer envelope proteins PDV1 and PDV2, which have parallel functions in dynamin recruitment. PDV2 positioning involves direct ARC6–PDV2 interaction, but PDV1 and ARC6 do not interact indicating that an additional factor functions downstream of ARC6 to position PDV1. Here, we show that PARC6 (paralog of ARC6), an ARC6-like protein unique to vascular plants, fulfills this role. Like ARC6, PARC6 is an inner envelope protein with its N-terminus exposed to the stroma and Arabidopsis parc6 mutants exhibit defects of chloroplast and FtsZ filament morphology. However, whereas ARC6 promotes FtsZ assembly, PARC6 appears to inhibit FtsZ assembly, suggesting that ARC6 and PARC6 function as antagonistic regulators of FtsZ dynamics. The FtsZ inhibitory activity of PARC6 may involve its interaction with the FtsZ-positioning factor ARC3. A PARC6–GFP fusion protein localizes both to the mid-plastid and to a single spot at one pole, reminiscent of the localization of ARC3, PDV1 and ARC5. Although PARC6 localizes PDV1, it is not required for PDV2 localization or ARC5 recruitment. Our findings indicate that PARC6, like ARC6, plays a role in coordinating the internal and external components of the chloroplast division complex, but that PARC6 has evolved distinct functions in the division process. 相似文献
60.
Renaud Beaudegnies Andrew J.F. Edmunds Torquil E.M. Fraser Roger G. Hall Timothy R. Hawkes Glynn Mitchell Juergen Schaetzer Sebastian Wendeborn Jane Wibley 《Bioorganic & medicinal chemistry》2009,17(12):4134-4152
A review, outlining the origins and subsequent development of the triketone class of herbicidal 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors. 相似文献