全文获取类型
收费全文 | 364篇 |
免费 | 44篇 |
国内免费 | 1篇 |
出版年
2021年 | 8篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2016年 | 5篇 |
2015年 | 11篇 |
2014年 | 11篇 |
2013年 | 13篇 |
2012年 | 20篇 |
2011年 | 19篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 18篇 |
2007年 | 10篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1971年 | 9篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 4篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1962年 | 3篇 |
排序方式: 共有409条查询结果,搜索用时 46 毫秒
21.
Experiments using a Ca2+/Mg2+, serum free media were carried out aimed at clarifying proposed effects of these divalent cations on in vitro meiotic maturation of mouse and cow oocytes. Agents known to perturb intracellular Ca2+ or calmodulin were also studied. Total absence of both cations restricts both oocyte species from completing meiosis I. Media containing Mg2+ and no Ca2+ permitted some maturation in both species. Absence or small amounts of Mg2+ in the media containing control amounts of Ca2+ was much more inhibitory for the cow than the mouse oocyte. Studies of mouse oocyte maturation with Verapamil, Epinephrine and A23187 demonstrated an inhibition of maturation perhaps by the intracellular Ca2+ changes these agents are alleged to induce. A dependency of mouse oocyte maturation on active Ca-Calmodulin complexes was suggested by the calmodulin inhibitor studies. 相似文献
22.
23.
24.
Kinetic properties of Serratia marcescens adenosine 5''-diphosphate glucose pyrophosphorylase.
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The regulatory properties of partially purified adenosine 5'-diphosphate-(ADP) glucose pyrophosphorylase from two Serratia marcescens strains (ATCC 274 and ATCC 15365) have been studied. Slight or negligible activation by fructose-P2, pyridoxal-phosphate, or reduced nicotinamide adenine dinucleotide phosphate (NADPH) was observed. These compounds were previously shown to be potent activators of the ADPglucose pyrophosphorylases from the enterics, Salmonella typhimurium, Enterobacter aerogenes, Enterobacter cloacae, Citrobacter freundii, Escherichia aurescens, Shigella dysenteriae, and Escherichia coli. Phosphoenolpyruvate stimulated the rate of ADPglucose synthesis catalyzed by Serratia ADPglucose pyrophosphorylase about 1.5- to 2-fold but did not affect the S0.5 values (concentration of substrate required for 50% maximal stimulation) of the substrates, alpha-glucose-1-phosphate, and adenosine 5'-triphosphate. Adenosine 5'-monophosphate (AMP), a potent inhibitor of the enteric ADPglucose pyrophosphorylase, is an effective inhibitor of the S. marcescens enzyme. ADP also inhibits but is not as effective as AMP. Activators of the enteric enzyme counteract the inhibition caused by AMP. This is in contrast to what is observed for the S. marcescens enzyme. Neither phosphoenolpyruvate, fructose-diphosphate, pyridoxal-phosphate, NADPH, 3-phosphoglycerate, fructose-6-phosphate, nor pyruvate effect the inhibition caused by AMP. The properties of the S. marcescens HY strain and Serratia liquefaciens ADPglucose pyrophosphorylase were found to be similar to the above two S. marcescens enzymes with respect to activation and inhibition. These observations provide another example where the properties of an enzyme found in the genus Serratia have been found to be different from the properties of the same enzyme present in the enteric genera Escherichia, Salmonella, Shigella, Citrobacter, and Enterobacter. 相似文献
25.
26.
27.
In Parkinson''s disease, the long-term use of dopamine replacing agents is associated with the development of motor complications; therefore, there is a need for non-dopaminergic drugs. This study evaluated the potential therapeutic impact of six different NR2B and A2A receptor antagonists given either alone or in combination in unilateral 6-OHDA-lesioned rats without (monotherapy) or with (add-on therapy) the co-administration of L-Dopa: Sch-58261+ Merck 22; Sch-58261+Co-101244; Preladenant + Merck 22; Preladenant + Radiprodil; Tozadenant + Radiprodil; Istradefylline + Co-101244. Animals given monotherapy were assessed on distance traveled and rearing, whereas those given add-on therapy were assessed on contralateral rotations. Three-way mixed ANOVA were conducted to assess the main effect of each drug separately and to determine whether any interaction between two drugs was additive or synergistic. Additional post hoc analyses were conducted to compare the effect of the combination with the effect of the drugs alone. Motor activity improved significantly and was sustained for longer when the drugs were given in combination than when administered separately at the same dose. Similarly, when tested as add-on treatment to L-Dopa, the combinations resulted in higher levels of contralateral rotation in comparison to the single drugs. Of special interest, the activity observed with some combinations could not be described by a simplistic additive effect and involved more subtle synergistic pharmacological interactions. The combined administration of A2A/NR2B-receptor antagonists improved motor behaviour in 6-OHDA rats. Given the proven translatability of this model such a combination may be expected to be effective in improving motor symptoms in patients. 相似文献
28.
29.
Dorjee Johnson Stephen B. Buckmaster Anthony J. Downey Paul O. 《Biological invasions》2021,23(9):2945-2959
Biological Invasions - Intentional introduction of alien plant species through increased global trade and movement of people worldwide has contributed to the current problem of invasion by alien... 相似文献
30.
Jason D. Downey Sam A. Saleh Thomas M. Bridges Ryan D. Morrison J. Scott Daniels Craig W. Lindsley Richard M. Breyer 《Bioorganic & medicinal chemistry letters》2013,23(1):37-41
Recent preclinical studies demonstrate a role for the prostaglandin E2 (PGE2) subtype 1 (EP1) receptor in mediating, at least in part, the pathophysiology of hypertension and diabetes mellitus. A series of amide and N-acylsulfonamide analogs of a previously described picolinic acid-based human EP1 receptor antagonist (7) were prepared. Each analog had improved selectivity at the mouse EP1 receptor over the mouse thromboxane receptor (TP). A subset of analogs gained affinity for the mouse PGE2 subtype 3 (EP3) receptor, another potential therapeutic target. One analog (17) possessed equal selectivity for EP1 and EP3, displayed a sufficient in vivo residence time in mice, and lacked the potential for acyl glucuronide formation common to compound 7. Treatment of mice with 17 significantly attenuated the vasopressor activity resulting from an acute infusion of EP1 and EP3 receptor agonists. Compound 17 represents a potentially novel therapeutic in the treatment of hypertension and diabetes mellitus. 相似文献