全文获取类型
收费全文 | 127篇 |
免费 | 31篇 |
出版年
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1965年 | 3篇 |
1908年 | 1篇 |
1903年 | 1篇 |
1897年 | 1篇 |
1890年 | 1篇 |
1887年 | 1篇 |
排序方式: 共有158条查询结果,搜索用时 31 毫秒
21.
Mushtaq A. Saleem Abdul Rauf Shakoori David Mantle 《Archives of insect biochemistry and physiology》1998,39(4):144-154
The effects of a synthetic pyrethroid insecticide, cypermethrin, administered as a formulation Ripcord 25EC (emulsified concentrate), to adult beetles of a stored grain pest, Tribolium castaneum, have been studied, with an objective to ascertain its toxicity on enzymes such as carbohydrases, phosphatases, dehydrogenases, aminotransferases, and concentration of various biochemical components such as monosaccharides, glycogen, cholesterol, nucleic acids, urea, total lipids, and total proteins. Almost all the enzymes and biochemical components were sensitive to sublethal doses of Ripcord 25 EC and these effects were found to be dependent on the duration of treatment. All carbohydrate metabolizing enzymes (amylase, invertase, lactase, maltase, lactate dehydrogenase) were elevated, except for trehalase, which was also elevated up to day 3 but returned to normal levels subsequently. Phosphatases (alkaline as well as acidic) were increased first and decreased thereafter, while isocitrate dehydrogenase decreased throughout the experimental period. Transaminases (aspartate aminotransferase and alanine aminotransferase) showed a decreasing trend. Of the other biochemical components tested, glucose content decreased during the first 3 days but increased subsequently. Fructose content showed an increase, while the glycogen content decreased throughout the study. Total lipid content was not disturbed up to day 3 but increased thereafter. Cholesterol content was depleted by day 7. Total proteins started decreasing from day 3 onwards, while soluble proteins were not affected. DNA, RNA, and urea contents exhibited elevated levels, while uric acid showed a decreasing trend. Sublethal doses of Ripcord, therefore, resulted in extensive enzyme induction, and utilization of carbohydrates, proteins, and lipids, in the given order, perhaps to produce extra energy to combat insecticidal stress. Arch. Insect Biochem. Physiol. 39:144–154, 1998. © 1998 Wiley-Liss, Inc. 相似文献
22.
D Taruscio C Morciano P Laricchiuta P Mincarone F Palazzo CG Leo S Sabina R Guarino J Auld T Sejersen D Gavhed K Ritchie M Hilton-Boon J Manson PG Kanavos D Tordrup V Tzouma Y Le Cam J Senecat G Filippini S Minozzi C Del Giovane H Schünemann JJ Meerpohl B Prediger L Schell R Stefanov G Iskrov T Miteva-Katrandzhieva P Serrano-Aguilar L Perestelo-Perez MM Trujillo-Martín J Pérez-Ramos A Rivero-Santana A Brand H van Kranen K Bushby A Atalaia J Ramet L Siderius M Posada I Abaitua-Borda V Alonso Ferreira M Hens-Pérez FJ Manzanares 《Orphanet journal of rare diseases》2014,9(Z1):O14
23.
Ana C. Coan Brunno M. Campos Clarissa L. Yasuda Bruno Y. Kubota Felipe PG. Bergo Carlos AM. Guerreiro Fernando Cendes 《PloS one》2014,9(1)
Objective
Patients with temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) have diffuse subtle gray matter (GM) atrophy detectable by MRI quantification analyses. However, it is not clear whether the etiology and seizure frequency are associated with this atrophy. We aimed to evaluate the occurrence of GM atrophy and the influence of seizure frequency in patients with TLE and either normal MRI (TLE-NL) or MRI signs of HS (TLE-HS).Methods
We evaluated a group of 172 consecutive patients with unilateral TLE-HS or TLE-NL as defined by hippocampal volumetry and signal quantification (122 TLE-HS and 50 TLE-NL) plus a group of 82 healthy individuals. Voxel-based morphometry was performed with VBM8/SPM8 in 3T MRIs. Patients with up to three complex partial seizures and no generalized tonic-clonic seizures in the previous year were considered to have infrequent seizures. Those who did not fulfill these criteria were considered to have frequent seizures.Results
Patients with TLE-HS had more pronounced GM atrophy, including the ipsilateral mesial temporal structures, temporal lobe, bilateral thalami and pre/post-central gyri. Patients with TLE-NL had more subtle GM atrophy, including the ipsilateral orbitofrontal cortex, bilateral thalami and pre/post-central gyri. Both TLE-HS and TLE-NL showed increased GM volume in the contralateral pons. TLE-HS patients with frequent seizures had more pronounced GM atrophy in extra-temporal regions than TLE-HS with infrequent seizures. Patients with TLE-NL and infrequent seizures had no detectable GM atrophy. In both TLE-HS and TLE-NL, the duration of epilepsy correlated with GM atrophy in extra-hippocampal regions.Conclusion
Although a diffuse network GM atrophy occurs in both TLE-HS and TLE-NL, this is strikingly more evident in TLE-HS and in patients with frequent seizures. These findings suggest that neocortical atrophy in TLE is related to the ongoing seizures and epilepsy duration, while thalamic atrophy is more probably related to the original epileptogenic process. 相似文献24.
25.
The structure of a novel diketopiperazine metabolite, named nigrifortine, isolated from cultures of Penicillium nigricans is deduced from its 1H NMR, mass and UV spectra together with biosynthetic reasoning. 相似文献
26.
Fidel Toldra Gavin Falkous Monica Flores David Mantle 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1996,115(4):445-450
We compared the inhibitory action of individual amino acids in vitro on the activities of alanyl-, arginyl-, leucyl- and pyroglutamyl aminopeptidases purified from human and porcine skeletal muscle tissues. The range of susceptibility to inhibition by individual amino acids (<25 mM) for different aminopeptidase types broadly paralleled that for the respective substrate specificities (in terms of relative rates of hydrolysis of amino acyl-AMC derivatives) for these enzymes. Thus, alanyl aminopeptidase (which hydrolyses a broad range of aminoacyl-AMC substrates) was inhibited by a correspondingly broad range of amino acids (although the respective ranking order of amino acids was not identical in each case), whereas pyroglutamyl aminopeptidase (which hydrolyses only pyroglutamyl AMC as substrate) was inhibited by pyroglutamic acid only. The mode of inhibition (competitive/non-competitive) varied for different enzyme types, both within and between each species. For enzymes purified from human muscle, alanyl, arginyl and leucyl aminopeptidases were inhibited by amino acids via the non-competitive mode (pyroglutamyl aminopeptidase via the competitive mode), whereas corresponding enzymes purified from porcine muscle were inhibited via the competitive mode. The data obtained indicate that the same aminopeptidase types are present in human and porcine skeletal muscle tissues, with corresponding enzymes having broadly similar assay characteristics and susceptibilities to inhibition by amino acids (although the mode of inhibition for corresponding enzymes may differ in each species). Such data obtained in vitro may prove of value in devising experimental strategies to manipulate protein turnover/muscle deposition in vivo, via inhibition of aminopeptidase action after administration of an appropriate admixture of amino acids. 相似文献
27.
P G Mantle K P Perera N J Maishman G R Mundy 《Applied and environmental microbiology》1983,45(5):1486-1490
Roquefortine and the penitrems were biosynthesised concurrently at an approximately equimolar rate by Penicillium crustosum after growth and sporulation. [14C]mevalonic acid was incorporated (15% efficiency) into the isoprenoid regions of the penitrem and roquefortine molecules to an extent consistent with their 6:1 molar ratio of isoprenoid components. [14C]penitrem A (specific activity, 3.4 X 10(2) mu Ci mmol-1) and 14C-penitrems B, C, and E readministered to young cultures were metabolically interconverted, indicating considerable metabolic flux, though generally directed towards penitrem A as the end product and suggesting a metabolic grid for the penitrem metabolites. Addition of bromide to the medium preferentially favored the production of bromo-analogs rather than the usual chloropenitrems. 相似文献
28.
The effect of pH on the kinetics of rat liver arylsulphatases A and B is very similar and shows that two groups with pK values of 4.4-4.5 and 5.7-5.8 are important for enzyme activity. Substrate binding has no effect on the group with a pK of 4.4-4.5; however, the pK of the second group is shifted to 7.1-7.5 in the enzyme-substrate complex. An analysis of the effect of pH on the Ki for sulphate inhibition suggests that HSO4-is the true product. A model is proposed that involves the two ionizing groups identified in the present study in a concerted general acid-base-catalysed mechanism. 相似文献
29.
Novel metabolites from Penicillium crustosum, including penitrem E, a tremorgenic mycotoxin. 总被引:1,自引:1,他引:0 下载免费PDF全文
Two new indolic metabolites were isolated from Penicillium crustosum and separated from other penitrem mycotoxins by high-performance liquid chromatography. Penitrem D is a deoxy-penitrem A. Penitrem E is dechloro-penitrem A and was shown to be tremorgenic in mice, although it has only one-third of the activity of penitrem A. Roquefortine was also shown, for the first time, to be an important metabolic product of P. crustosum. 相似文献
30.
A novel process for the production of penitrem mycotoxins by submerged fermentation of Penicillium nigricans 总被引:1,自引:0,他引:1
A strain of Penicillium nigricans, which produces both the antifungal antibiotic griseofulvin and tremorgenic penitrem mycotoxins concurrently in static liquid culture, also elaborated both metabolites in submerged culture when stimulated by calcium chloride to sporulate. Maximum yield of penitrems (60 mg l-1) occurred within 5 d in a 60 l stirred fermenter, thus constituting the first significant process for penitrem production in submerged culture. 相似文献