全文获取类型
收费全文 | 564篇 |
免费 | 50篇 |
出版年
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 19篇 |
2017年 | 11篇 |
2016年 | 24篇 |
2015年 | 27篇 |
2014年 | 32篇 |
2013年 | 38篇 |
2012年 | 44篇 |
2011年 | 36篇 |
2010年 | 35篇 |
2009年 | 28篇 |
2008年 | 25篇 |
2007年 | 38篇 |
2006年 | 27篇 |
2005年 | 28篇 |
2004年 | 15篇 |
2003年 | 20篇 |
2002年 | 24篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1942年 | 1篇 |
排序方式: 共有614条查询结果,搜索用时 271 毫秒
121.
122.
Dorothee Heuermann Peter Roggentin Reinhard G. Kleineidam Roland Schauer 《Glycoconjugate journal》1991,8(2):95-101
The sialidase secreted byClostridium chauvoei NC08596 was purified to apparent homogeneity by ion-exchange chromatography, gel filtration, hydrophobic interaction-chromatography, FPLC ion-exchange chromatography, and FPLC gel filtration. The enzyme was enriched about 10 200-fold, reaching a final specific activity of 24.4 U mg–1. It has a relatively high molecular mass of 300 kDa and consists of two subunits each of 150 kDa. The cations Mn2+, Mg2+, and Ca2+ and bovine serum albumin have a positive effect on the sialidase activity, while Hg2+, Cu2+, and Zn2+, chelating agents and salt decrease enzyme activity. The substrate specificity, kinetic data, and pH optimum of the enzyme are similar to those of other bacterial sialidases.Abbreviations FPLC
fast protein liquid chromatography
- NCTC
National Collection of Type Cultures
- ATCC
American Type Culture Collection
- MU-Neu5Ac
4-methylumbelliferyl--d-N-acetylneuraminic acid
- buffer A
0.02m piperazine, 0.01m CaCl2, pH 5.5
- buffer B
0.02m piperazine, 0.01m CaCl2, 1.0m NaCl, pH 5.5
- buffer C
0.1m sodium acetate, 0.01m CaCl2, pH 5.5
- SDS
sodium dodecyl sulfate
- PAGE
polyacrylamide gel electrophoresis
- Neu5Ac
N-acetylneuraminic acid
- BSM
bovine submandibular gland mucin
- GD1a
IV3Neu5Ac, II3Neu5Ac-GgOse4Cer
- GM1
II3Neu5Ac-GgOse4Cer
- MU-Neu4,5Ac2
4-methylumbelliferyl--d-N-acetyl-4-O-acetylneuraminic acid
- TLC
thin-layer chromatography
- HPTLC
high performance thin-layer chromatography
- EDTA
ethylenediamine tetraacetic acid
- EGTA
ethylene glycol bis(2-aminoethyl-ethen)-N,N,N,N-tetraacetic acid
- BSA
bovine serum albumin
- Neu5Ac2en
2-deoxy-2,3-didehydro-N-acetylneuraminic acid
- IEF
isoelectric focusing
- IEP
isoelectric point 相似文献
123.
Production, purification and characterization of hemolysins from Listeria ivanovii and Listeria monocytogenes Sv4b 总被引:12,自引:0,他引:12
Jürgen Kreft Dorothee Funke Albert Haas Friedrich Lottspeich Werner Goebel 《FEMS microbiology letters》1989,57(2):197-202
In culture supernatants of both Listeria ivanovii and Listeria monocytogenes Sv4b, for the first time a hemolysin of molecular weight 58 kDa was identified, which had all the characteristics of an SH-activated cytolysin, and which was therefore identified as listeriolysin O (LLO). In the case of L. ivanovii a second major supernatant protein of molecular weight 24 kDa co-purified with LLO. However, the function of this protein has to be determined. In culture supernatants of L. ivanovii a sphingomyelinase and a lecithinase activity could be detected, both enzymatic activities together contributing to the pronounced hemolysis caused by L. ivanovii. The N-terminal amino acid sequences of LLO and the 24 kDa from L. ivanovii are shown. 相似文献
124.
125.
Maintaining pH and blood gases in a narrow range is essential to sustain normal biochemical reactions. Decreased oxygenation, poor tissue perfusion, disturbance to CO2 expiration, and shortage of HCO3 − can lead to metabolic acidosis. This is a common situation in swine, and originates from a broad range of medical conditions. pH and blood gases appear to be under genetic control, and populations with physiological traits closer to the pathological thresholds may be more susceptible to developing pathological conditions. However, little is known about the genetic basis of such traits. We have therefore estimated phenotypic and genetic variability and identified quantitative trait loci (QTL) for pH and blood gases in blood samples from 139 F2 pigs from the Meishan/Pietrain family. Samples were taken before and after challenge with Sarcocystis miescheriana , a protozoan parasite of muscle. Twenty-seven QTL influencing pH and blood gases were identified on nine chromosomes. Five of the QTL were significant on a genome-wide level; 22 QTL were significant on a chromosome-wide level. QTL for pH-associated traits have been mapped to SSC3, 18 and X. QTL associated with CO2 have been detected on SSC6, 7, 8 and 9, and QTL associated with O2 on SSC2 and SSC8. QTL showed specific health/disease patterns that were related to the physiological state of the pigs from day 0, to acute disease (day 14), convalescence (day 28) and chronic disease (day 42). The results demonstrate that pH and blood gases are influenced by multiple chromosomal areas, each with relatively small effects. 相似文献
126.
G. L. Gonçalves G. R. P. Moreira T. R. O. Freitas D. Hepp D. T. Passos T. A. Weimer 《Animal genetics》2010,41(3):308-310
Using ND5 sequences from mtDNA and 10 nuclear markers, we investigated the genetic differentiation of two South American Creole sheep phenotypes that historically have been bred in different biomes in southern Brazil. In total, 18 unique mtDNA haplotypes were detected, none of which was shared between the two phenotypes. Bayesian analysis also indicated two different groups (k = 2). Thus, these varieties are supported as being genotypically distinct. This situation could have resulted either from geographical isolation, associated with differences in the cultural habits of sheep farmers and in the way that flocks were managed, or more likely, from the introduction of different stocks four centuries ago. 相似文献
127.
Weiling Wang Hao Xu Yang Shi Sandhya Nandedkar Hao Zhang Haiqing Gao Thom Feroah Dorothee Weihrauch Marie L. Schulte Deron W. Jones Jason Jarzembowski Mary Sorci-Thomas Kirkwood A. Pritchard Jr. 《Journal of lipid research》2010,51(9):2560-2570
The relationship between high-density lipoprotein and pulmonary function is unclear. To determine mechanistic relationships we investigated the effects of genetic deletion of apolipoprotein A-I (apoA-I) on plasma lipids, paraoxonase (PON1), pro-inflammatory HDL (p-HDL), vasodilatation, airway hyperresponsiveness and pulmonary oxidative stress, and inflammation. ApoA-I null (apoA-I−/−) mice had reduced total and HDL cholesterol but increased pro-inflammatory HDL compared with C57BL/6J mice. Although PON1 protein was increased in apoA-I−/− mice, PON1 activity was decreased. ApoA-I deficiency did not alter vasodilatation of facialis arteries, but it did alter relaxation responses of pulmonary arteries. Central airway resistance was unaltered. However, airway resistance mediated by tissue dampening and elastance were increased in apoA-I−/− mice, a finding also confirmed by positive end-expiratory pressure (PEEP) studies. Inflammatory cells, collagen deposition, 3-nitrotyrosine, and 4-hydroxy-2-nonenal were increased in apoA-I−/− lungs but not oxidized phospholipids. Colocalization of 4-hydroxy-2-nonenal with transforming growth factor β-1 (TGFβ-1 was increased in apoA-I−/− lungs. Xanthine oxidase, myeloperoxidase and endothelial nitric oxide synthase were increased in apoA-I−/− lungs. Dichlorodihydrofluorescein-detectable oxidants were increased in bronchoalveolar lavage fluid (BALF) in apoA-I−/− mice. In contrast, BALF nitrite+nitrate levels were decreased in apoA-I−/− mice. These data demonstrate that apoA-I plays important roles in limiting pulmonary inflammation and oxidative stress, which if not prevented, will decrease pulmonary artery vasodilatation and increase airway hyperresponsiveness. 相似文献
128.
Two new oribatid mite species of the genus Truncozetes (Oribatida, Epactozetidae), Truncozetes ecuadoriensis
sp. n. and Truncozetes monodactylus
sp. n., are described from the Ecuadorian soils. The morphology of the gnathosoma and the legs is presented in detail for the first time for the species of Truncozetes. An identification key to all known species of the family Epactozetidae is given. 相似文献
129.
MDHM, a macrophage-activating product of Mycoplasma fermentans, stimulates murine macrophages to synthesize nitric oxide and become tumoricidal 总被引:1,自引:0,他引:1
Dorothee Ruschmeyer Hansjörg Thude Peter F. Mühlradt 《FEMS immunology and medical microbiology》1993,7(3):223-230
Abstract In continuation of previous work on macrophage activation by a Mycoplasma fermentans -derived product, originally named “mycoplasma-derived high mol. wt. material” (MDHM), we have investigated whether MDHM was capable of inducing synthesis of the reactive nitrogen intermediate nitric oxide (NO), thus rendering macrophages cytocidal. Mycoplasmas were first delipidated with acetone, and MDHM activity was then extracted with 50 mM 1-O-octyl-β- d -glucopyranoside to yield a particularly active new preparation of MDHM which we have named MDHM-D (D for detergent). In combination with IFN-γ, MDHM-D activated macrophages to produce reactive nitrogen intermediates and kill P815 mastocytoma cells in co-culture. P815 target cells were chosen because they are TNF-resistant. Macrophages from the LPS-low responder strain C3H/HeJ were used to minimize interference from possible LPS contamination. MDHM-D activity in this system was strictly IFN-γ-dependent. In the presence of 25 U/ml IFN-γ MDHM-D gave a half maximal response at a dilution of 1/100 000, showing a parallel concentration dependency for nitrite production and cytocidal activity. 相似文献
130.
Racemic synthetic 3HC18 juvenile hormone, dissolved in paraffin oil, was injected into adult Locusta migratoria and the excreted radioactive material in the faeces was determined. Within 48 hr two-thirds of the injected radioactivity can be recovered in the frass, half of it within 3 hr. The remaining one-third of the injected label is incorporated or is released as water. Adult locusts of either sex or of different ages show no difference in the metabolic pathways of the JH and its excretion rate.The excreta contain as a degradation product 7-ethyl-3,11-dimethyl-cis-10,11-epoxy-trans, trans-2,6 trideca-dienoic acid, the corresponding dioldienoic acid and the dioldienoic methyl ester. Unchanged Cecropia JH was also found in the frass. The radioactive hormone, as well as the metabolites, were excreted mainly by the Malpighian tubules; smaller amounts of the radioactive material were also found in the fore-, mid, and hindgut. 相似文献