全文获取类型
收费全文 | 129篇 |
免费 | 5篇 |
专业分类
134篇 |
出版年
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1973年 | 5篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1965年 | 1篇 |
1962年 | 4篇 |
1960年 | 4篇 |
1959年 | 1篇 |
1955年 | 2篇 |
1953年 | 2篇 |
1930年 | 1篇 |
1925年 | 1篇 |
1924年 | 2篇 |
1923年 | 4篇 |
1922年 | 2篇 |
1921年 | 3篇 |
排序方式: 共有134条查询结果,搜索用时 15 毫秒
31.
The time course of production of odorous compounds, i.e. geosmin and oxolones, and of avermectins was determined during the cultivation of S. avermitilis in flasks, 1- and 50-L fermentors. The amount of the antibiotics increased with increasing cultivation time up to more than 2 g/L while the concentration of geosmin rose to more than 4 mg/L. Cultivation without reflux condenser resulted in a lower product formation due to the higher stripping of geosmin. A relatively tight correlation was found between the production of geosmin and the production of avermectins. The production of oxolones peaked on cultivation days 3-5, the sum of oxolones being 60 microg/L. Subsequently, the production dropped below a measurable level. This can be explained as being due to the inhibition of oxolone production by geosmin. 相似文献
32.
33.
Keilhoff G Prell T Langnaese K Mawrin C Simon M Fansa H Nicholas AP 《Developmental neurobiology》2008,68(1):101-114
The peptidylarginine deiminase (PAD) family of enzymes are responsible for conversion of protein-bound arginine to citrulline in most tissues of the body and are garnering increased interest for their physiological and pathological roles. Although it has been shown that oligodendrocytes of the CNS express the PAD isoenzyme type 2, nothing is presently known about PAD expression in Schwann cells, the myelinating cells of the PNS. To evaluate PAD expression in the PNS, cultivated rat and human Schwann cells and slices of fetal, juvenile, and normal and regenerated adult sciatic nerves were examined with RT-PCR, Western blot, and immunohistochemical analysis. Samples from cerebellar cultures and skin served as positive controls. One of the principle findings was that cultivated Schwann cells expressed significant levels of mRNA and protein for the PAD isoenzymes 2 and 3. PAD1 and PAD4, however, were not expressed in any types of Schwann cells. Using double immunofluorescence, the majority of PAD2 staining was localized in immature cell stages. Moreover, increased amounts of PAD2, PAD3, and peptidyl-citrulline were also found in human fetal and rat juvenile and regenerated sciatic nerves as compared to similar normal adult specimens. Neuronal and inducible nitric oxide synthases, enzymes that convert free arginine to citrulline, were also expressed in Schwann cells; however, their massive induction by LPS/K(+), was not reflected in an enhanced peptidyl-citrulline immunosignal. These data suggest that, similar to the CNS, citrullination of proteins may also exert a specific role in thecourse of PNS development and repair. 相似文献
34.
George D. Prell Albert M. Morrishow Erwin Duoyon Wah S. Lee 《Journal of neurochemistry》1997,68(1):142-151
Abstract: In brain, the precursor of imidazoleacetic acid (IAA), a GABAA agonist but a GABAC antagonist, is not known. In the periphery, IAA derives from oxidation of histamine. But in brain, histamine is thought to be metabolized solely by histamine methyltransferase (HMT), forming tele -methylhistamine (t-MH) and tele -methylimidazoleacetic acid (t-MIAA). We showed that [3 H]histamine (intracerebroventricularly) could be converted to IAA in brains of rats, a process increased by inhibition of HMT. This demonstrated that brain can oxidize histamine and suggested that endogenous histamine might also be oxidized if HMT activity were reduced. We examined, in rat cerebral cortex, effects of the following HMT inhibitors (mg/kg i.p.): metoprine (10), tacrine (10), velnacrine (10, 30), and physostigmine (1, 2). Tacrine was a potent inhibitor ( K i ∼ 22 n M ). To measure histamine in tissue that contained HMT inhibitors, we developed a gas chromatography-mass spectrometry method. After 2 h, all drugs reduced endogenous levels of t-MH and t-MIAA and increased levels of histamine and IAA. Our results show that inhibition of HMT promotes oxidation of histamine in brain, probably by shunting histamine to an alternative metabolic pathway. Formation of IAA provides a novel interaction between histaminergic and GABAergic systems in brain. Accumulation of IAA should be considered when inhibitors of HMT are used to probe brain histamine function. 相似文献
35.
36.
Summary Ion fluxes after ethanol addition to Candida utilis depend crucially on aeration (air versus oxygen). In O2-aerated non-growing cells ethanol causes an H + / K + exchange and an extrusion of acetate and lactate accompanied mostly by K +, and their subsequent reimportation together with H +. Cells from continuous culture display generally stronger acidification and more marked K + movements than non-growing ones.
Offprint requests to: A. Prell 相似文献
37.
Summary Phage P22 defective in gene 24 and harbouring the oc mutation k5 in OR exhibits a strongly increased c2-repressor synthesis after infection of non-lysogenic S. typhimurium. The repressor synthesis depends strictly on an intact c1 gene. The kinetics of its synthesis, as monitored by polyacrylamid gel electrophoresis, is the same as with P22 c
+, namely a turn off 8–10 min after infection. — After infection of P22-lysogenic bacteria with either P22 24
–
k5 or P22 24
–
k5 cl, much lower amounts of repressor are synthesized but again with the same kinetics. These results suggest a cro-like function acting at PRE and PRM of P22. The possible reason for the c2 overproduction is discussed. 相似文献
38.
In oxygen-aerated non-growing cells a subinhibitory ethanol concentration (1 g/L) causes an H+/K+ exchange. An inhibitory ethanol concentration (30 g/L) slows down acidification but has no effect on its extent. The transmembrane
ΔpH depends directly on the ethanol level in the medium and is not lowered at high ethanol concentrations. Changes in membrane
potential induced by ethanol are also concentration dependent. The high ethanol level does not increase the passive permeability
of cell membrane to H+. 相似文献
39.
Summary Phage mutants were isolated with amber mutations in genes necessary for establishment of lysogeny. These mutants form turbid plaques on su
+ strain 527R1 and clear plaques of different types on LT2. According to complementation tests, fourteen mutants fall in the c
2 gene, four in the c
3 gene but no amber mutants were found belonging to the c
1 gene. Pulse labelling experiments to follow DNA synthesis after phage infection were done with the mutants classified by complementation tests. Furthermore the labelling experiments demonstrated that the nonleaky c
3 amber mutants displayed the same DNA synthesis pattern as c
1 missense mutants. Since these c
3 amber mutants complement missense c
1 mutants it is concluded that the c
3 and c
1 genes must act together for the first transient repression of DNA synthesis, i.e., seven minutes after infection. It is suggested that clear plaque forming c
1 amber mutants cannot be isolated because of polarity leading to defectivity of lysogenic as well as of lytic functions.The majority of the experiments presented are a part of the dissertation of H. D. Dopatka at the University of Göttingen. 相似文献
40.
Burgeff F. Alverdes Küster Roux H. Stieve W. Kornfeld H. Prell Wetzel Dr. G. Ettisch A. Pratje B. Klatt 《Development genes and evolution》1922,50(3-4):618-644
Ohne Zusammenfassung 相似文献