全文获取类型
收费全文 | 114篇 |
免费 | 15篇 |
出版年
2021年 | 1篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有129条查询结果,搜索用时 171 毫秒
91.
92.
Long-Term Effects of Metal-Rich Sewage Sludge Application on Soil Populations of Bradyrhizobium japonicum 总被引:5,自引:4,他引:1 下载免费PDF全文
The application of sewage sludge to land may increase the concentration of heavy metals in soil. Of considerable concern is the effect of heavy metals on soil microorganisms, especially those involved in the biocycling of elements important to soil productivity. Bradyrhizobium japonicum is a soil bacterium involved in symbiotic nitrogen fixation with Glycine max, the common soybean. To examine the effect of metal-rich sludge application on B. japonicum, the MICs for Pb, Cu, Al, Fe, Ni, Zn, Cd, and Hg were determined in minimal media by using laboratory reference strains representing 11 common serogroups of B. japonicum. Marked differences were found among the B. japonicum strains for sensitivity to Cu, Cd, Zn, and Ni. Strain USDA 123 was most sensitive to these metals, whereas strain USDA 122 was most resistant. In field studies, a silt loam soil amended 11 years ago with 0, 56, or 112 Mg of digested sludge per ha was examined for total numbers of B. japonicum by using the most probable number method. Nodule isolates from soybean nodules grown on this soil were serologically typed, and their metal sensitivity was determined. The number of soybean rhizobia in the sludge-amended soils was found to increase with increasing rates of sludge. Soybean rhizobia strains from 11 serogroups were identified in the soils; however, no differences in serogroup distribution or proportion of resistant strains were found between the soils. Thus, the application of heavy metal-containing sewage sludge did not have a long-term detrimental effect on soil rhizobial numbers, nor did it result in a shift in nodule serogroup distribution. 相似文献
93.
Technical comment on Boersma et al. (2016) Temperature driven changes in the diet preference of omnivorous copepods: no more meat when it's hot? Ecology Letters, 19, 45–53 下载免费PDF全文
Monika Winder Alfred Burian Michael R Landry David JS Montagnes Jens M. Nielsen 《Ecology letters》2016,19(11):1389-1391
A recent study concluded that omnivorous plankton will shift from predatory to herbivorous feeding with climate warming, as consumers require increased carbon:phosphorous in their food. Although this is an appealing hypothesis, we suggest the conclusion is unfounded, based on the data presented, which seem in places questionable and poorly interpreted. 相似文献
94.
The ability of particular cell surface glycoproteins to recycle and become
exposed to individual Golgi enzymes has been demonstrated. This study was
designed to determine whether endocytic trafficking includes significant
reentry into the overall oligosaccharide processing pathway. The Lec1
mutant of Chinese hamster ovary (CHO) cells lack N -
acetylglucosaminyltransferase I (GlcNAc-TI) activity resulting in surface
expression of incompletely processed Man5GlcNAc2 N -linked
oligosaccharides. An oligosaccharide tracer was created by exoglycosylation
of cell surface glycoproteins with purified porcine GlcNAc-TI and
UDP-[3H]GlcNAc. Upon reculturing, all cell surface glycoproteins that
acquired [3H]GlcNAc were acted upon by intracellular mannosidase II, the
next enzyme in the Golgi processing pathway of complex N -linked
oligosaccharides (t1/2= 3-4 h). That all radiolabeled cell surface
glycoproteins were included in this endocytic pathway indicates a common
intracellular compartment into which endocytosed cell surface glycoproteins
return. Significantly, no evidence was found for continued oligosaccharide
processing consistent with transit through the latter cisternae of the
Golgi apparatus. These data indicate that, although recycling plasma
membrane glycoproteins can be reexposed to individual Golgi-derived
enzymes, significant reentry into the overall contiguous processing pathway
is not evident.
相似文献
95.
In the current model for Glc3Man9GlcNAc2-P-P-Dol assembly, Man5GlcNAc2-
P-P-Dol, Man-P-Dol, and Glc-P-Dol are synthesized on the cytoplasmic face
of the ER and diffuse transversely to the lumenal leaflet where the
synthesis of the lipid-bound precursor oligosaccharide is completed. To
establish the topological sites of Glc-P-Dol synthesis and the
lipid-mediated glucosyltransfer reactions involved in
Glc3Man9GlcNAc2-P-P-Dol synthesis in ER vesicles from pig brain, the
trypsin-sensitivity of Glc-P-Dol synthase activity and the Glc-P-
Dol:Glc0-2Man9GlcNAc2-P-P-Dol glucosyltransferases (GlcTases) was examined
in sealed microsomal vesicles. Since ER vesicles from brain do not contain
glucose 6-phosphate (Glc 6-P) phosphatase activity, the latency of the
lumenally oriented, processing glucosidase I/II activities was used to
assess the intactness of the vesicle preparations. Comparative enzymatic
studies with sealed ER vesicles from brain and kidney, a tissue that
contains Glc 6-P phosphatase, demonstrate the reliability of using the
processing glucosidase activities as latency markers for topological
studies with microsomal vesicles from non-gluconeogenic tissues lacking Glc
6-P phosphatase. The results obtained from the trypsin-sensitivity assays
with sealed microsomal vesicles from brain are consistent with a
topological model in which Glc-P-Dol is synthesized on the cytoplasmic face
of the ER, and subsequently utilized by the three Glc-P-Dol-mediated
GlcTases after "flip-flopping" to the lumenal monolayer.
相似文献
96.
Validation of Microcosms for Examining the Survival of Pseudomonas aureofaciens (lacZY) in Soil 下载免费PDF全文
Evaluating the safety and efficacy of a recombinant bacterium prior to its release into the terrestrial environment requires that risk assessment data be collected in the laboratory. Much of this information is obtained with the use of microcosms. The design of the microcosm significantly affects the ability of the recombinant microorganism to survive in soil and, thus, complicates the risk assessment process. To standardize microcosms for future use, we evaluated the survival of Pseudomonas aureofaciens 3732 RN-L11 (lacZY Rif(supr) Nal(supr)) in intact soil cores (5.0 by 15 cm; polyvinyl chloride core) and disturbed soil microcosms (50 g of fresh, sieved soil). Survival data were compared with those obtained during a field release. The intact soil core microcosm was shown to closely simulate results obtained in the field. The intact soil core microcosm closely predicts survival in bulk soil and in the rhizosphere of wheat. Data obtained with the microcosm were also similar when evaluated in separate studies in two different years. In 1993, P. aureofaciens survived for approximately 63 days in bulk soil and 96 days in the rhizosphere. The disturbed soil microcosm exhibited a much more rapid decline in population size (34 days to zero) than the intact core microcosm. We speculate that drying and sieving of soil for the disturbed soil microcosm affected the ability of the soil to support the survival of P. aureofaciens. These results demonstrate that a small, inexpensive, and simple intact soil core microcosm may be appropriate for risk assessment. 相似文献
97.
98.
H. Abdel Basit J. S. Angle S. Salem E. M. Gewaily S. I. Kotob P. van Berkum 《Applied microbiology》1991,57(5):1570-1572
Thirty-four strains of Bradyrhizobium japonicum within serogroup 110 were examined for phenotypic diversity. The strains differed in their abilities to nodulate and fix dinitrogen with Glycine max (L.) Merr. cv. Williams. Thirteen strains expressed uptake hydrogenase activity when induced as free-living cultures in the presence of 2% hydrogen and oxygen. Six bacteriophage susceptibility reactions were observed. Each of the strains produced either a large, mucoid or a small, dry colony morphology, but colony type was not related to effectiveness for nitrogen fixation. 相似文献
99.
New Culture Medium Containing Ionic Concentrations of Nutrients Similar to Concentrations Found in the Soil Solution 总被引:6,自引:4,他引:2 下载免费PDF全文
A new growth medium which closely approximates the composition of the soil solution is presented. This soil solution equivalent (SSE) medium contains the following components (millimolar): NO3, 2.5; NH4, 2.5; HPO4, 0.005; Na, 2.5; Ca, 4.0; Mg, 2.0; K, 0.503; Cl, 4.0; SO4, 5.0; ethylenediamine-di(o-hydroxyphenylacetic acid), 0.02; and MES [2-(N-morpholino)ethanesulfonic acid] (to maintain the pH at 6.0), 10, plus 0.1% arabinose. The advantages of the SSE medium are discussed. 相似文献
100.
Junior Barrera Roberto M CesarJr Carlos HumesJr David C MartinsJr Diogo FC Patrão Paulo JS Silva Helena Brentani 《BMC bioinformatics》2007,8(1):169