全文获取类型
收费全文 | 395篇 |
免费 | 33篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 13篇 |
2012年 | 20篇 |
2011年 | 20篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 24篇 |
2007年 | 19篇 |
2006年 | 17篇 |
2005年 | 17篇 |
2004年 | 29篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 7篇 |
2000年 | 15篇 |
1999年 | 17篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1992年 | 17篇 |
1991年 | 10篇 |
1989年 | 12篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1975年 | 1篇 |
1974年 | 9篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有428条查询结果,搜索用时 15 毫秒
71.
Photosynthetica - In experiments with 5x5 diallel cross of tomato cv. Smr?ické contents of individual chlorophylls (Chl) and carotenoids (Car), Chl fluorescence kinetic parameters (Fv/Fm,... 相似文献
72.
Antigen-mediated macrophage adherence inhibition 总被引:1,自引:0,他引:1
Antigen-mediated macrophage adherence inhibition (MAI) was studied in inbred rats immunized with various transplantation, tumour-specific and protein antigens. A macrophage-rich suspension of peritoneal cells (PC) was obtained from the peritoneal cavity of immunized and control animals by washing. The adherence to glass of PC was specifically inhibited by the addition of the antigens used for sensitization of PC donors or by related (cross-reacting) antigens but not with unrelated antigens. The MAI seems to be due to the direct interaction of the respective antigen with a corresponding PC receptor and not due to the humoral factor released from immune lymphocytes of PC population upon contact with the specific antigen. 相似文献
73.
74.
Competition for Light between Toxic and Nontoxic Strains of the Harmful Cyanobacterium Microcystis 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
W. Edwin A. Kardinaal Linda Tonk Ingmar Janse Suzanne Hol Pieter Slot Jef Huisman Petra M. Visser 《Applied microbiology》2007,73(9):2939-2946
The cyanobacterium Microcystis can produce microcystins, a family of toxins that are of major concern in water management. In several lakes, the average microcystin content per cell gradually declines from high levels at the onset of Microcystis blooms to low levels at the height of the bloom. Such seasonal dynamics might result from a succession of toxic to nontoxic strains. To investigate this hypothesis, we ran competition experiments with two toxic and two nontoxic Microcystis strains using light-limited chemostats. The population dynamics of these closely related strains were monitored by means of characteristic changes in light absorbance spectra and by PCR amplification of the rRNA internal transcribed spacer region in combination with denaturing gradient gel electrophoresis, which allowed identification and semiquantification of the competing strains. In all experiments, the toxic strains lost competition for light from nontoxic strains. As a consequence, the total microcystin concentrations in the competition experiments gradually declined. We did not find evidence for allelopathic interactions, as nontoxic strains became dominant even when toxic strains were given a major initial advantage. These findings show that, in our experiments, nontoxic strains of Microcystis were better competitors for light than toxic strains. The generality of this finding deserves further investigation with other Microcystis strains. The competitive replacement of toxic by nontoxic strains offers a plausible explanation for the gradual decrease in average toxicity per cell during the development of dense Microcystis blooms. 相似文献
75.
76.
77.
Hofer M Pospísil M Znojil V Holá J Vacek A Streitová D 《Physiological research / Academia Scientiarum Bohemoslovaca》2008,57(2):307-310
Hematopoiesis-modulating action of meloxicam, a cyclooxyge-nase-2 inhibitor, has been evaluated in mice. Increased serum level of granulocyte colony-stimulating factor (G-CSF) after meloxicam administration has been found in sublethally gamma-irradiated animals. In further experiments hematopoiesis-stimulating effects of meloxicam and G-CSF given alone or in combination have been investigated. Granulocyte/macrophage progenitor cells counts were used to monitor these effects. Meloxicam and exogenous G-CSF did not act synergistically when given in combination, but could be mutually substituted during their repeated administration. The results suggest a promising possibility of using meloxicam as an auxiliary drug reducing the high costs of G-CSF therapy of myelosuppression. 相似文献
78.
Anzenbacherová E Anzenbacher P Zídek Z Buchar E Kmonícková E Potmesil P Nekvindová J Veinlichová A Holý A 《Physiological research / Academia Scientiarum Bohemoslovaca》2008,57(5):761-767
The total content of rat liver microsomal cytochrome P450 (CYP) significantly decreased after repeated i.p. administration of the antiviral agent tenofovir ((R)-9-[2-(phosphonomethoxy)propyl] adenine) and tenofovir disoproxil at a daily dose 25 mg/kg, although the content of liver microsomal protein did not change. The decrease of the CYP content was accompanied by concomitant increase of the amount of inactive CYP form, cytochrome P420. This effect was confirmed by a parallel study of the activities of selected CYP forms, CYP2E1 (p-nitrophenol hydroxylation) and CYP1A2 (7-ethoxyresorufin deethylation). The activity (expressed relatively to the protein content) of both CYP forms decreased significantly following the decrease of the total CYP. On the other hand, the CYP2E1 activity expressed relatively to the decreasing total CYP content remained unchanged. However, CYP1A2 activity also decreased when calculated relatively to the total native CYP content indicating lower stability of this form. Semiquantitative RT-PCR showed no significant changes in expression of major rat liver microsomal CYP forms after tenofovir treatment. In conclusion, repeated administration of tenofovir in higher doses led to significant decrease of the relative proportion of active liver microsomal CYPs accompanied by a conversion of these enzymes to the inactive form (CYP420) maintaining the sum of CYP proteins unchanged. 相似文献
79.
Hofer M Vacek A Pospísil M Holá J Streitová D Znojil V 《Physiological research / Academia Scientiarum Bohemoslovaca》2009,58(2):247-252
Adenosine A(3) receptor agonist N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA) has been tested from the point of view of potentiating the effects of hematopoietic growth factors interleukin-3 (IL-3), stem cell factor (SCF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and granulocyte colony-stimulating factor (G-CSF) on the growth of hematopoietic progenitor cells for granulocytes and macrophages (GM-CFC) in suspension of normal mouse bone marrow cells in vitro. IB-MECA alone induced no GM-CFC growth. Significant elevation of numbers of GM-CFC evoked by the combinations of IB-MECA with IL-3, SCF, or GM-CSF as compared with these growth factors alone has been noted. Combination of IB-MECA with G-CSF did not induce significantly higher numbers of GM-CFC in comparison with G-CSF alone. Joint action of three drugs, namely of IB-MECA + IL-3 + GM-CSF, produced significantly higher numbers of GM-CFC in comparison with the combinations of IB-MECA + IL-3, IB-MECA + GM-CSF, or IL-3 + GM-CSF. These results give evidence of a significant role of selective activation of adenosine A(3) receptors in stimulation of the growth of granulocyte/ macrophage hematopoietic progenitor cells. 相似文献
80.
Erin Quartley Andrei Alexandrov Maryann Mikucki Frederick S. Buckner Wim G. Hol George T. DeTitta Eric M. Phizicky Elizabeth J. Grayhack 《Journal of structural and functional genomics》2009,10(3):233-247
High level expression of many eukaryotic proteins for structural analysis is likely to require a eukaryotic host since many
proteins are either insoluble or lack essential post-translational modifications when expressed in E. coli. The well-studied eukaryote Saccharomyces cerevisiae possesses several attributes of a good expression host: it is simple and inexpensive to culture, has proven genetic tractability,
and has excellent recombinant DNA tools. We demonstrate here that this yeast exhibits three additional characteristics that
are desirable in a eukaryotic expression host. First, expression in yeast significantly improves the solubility of proteins
that are expressed but insoluble in E. coli. The expression and solubility of 83 Leishmania major ORFs were compared in S. cerevisiae and in E. coli, with the result that 42 of the 64 ORFs with good expression and poor solubility in E. coli are highly soluble in S. cerevisiae. Second, the yield and purity of heterologous proteins expressed in yeast is sufficient for structural analysis, as demonstrated
with both small scale purifications of 21 highly expressed proteins and large scale purifications of 2 proteins, which yield
highly homogeneous preparations. Third, protein expression can be improved by altering codon usage, based on the observation
that a codon-optimized construct of one ORF yields three-fold more protein. Thus, these results provide direct verification
that high level expression and purification of heterologous proteins in S. cerevisiae is feasible and likely to improve expression of proteins whose solubility in E. coli is poor. 相似文献