全文获取类型
收费全文 | 860篇 |
免费 | 63篇 |
出版年
2023年 | 6篇 |
2021年 | 10篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 19篇 |
2015年 | 31篇 |
2014年 | 37篇 |
2013年 | 49篇 |
2012年 | 64篇 |
2011年 | 38篇 |
2010年 | 33篇 |
2009年 | 26篇 |
2008年 | 40篇 |
2007年 | 44篇 |
2006年 | 36篇 |
2005年 | 64篇 |
2004年 | 40篇 |
2003年 | 49篇 |
2002年 | 41篇 |
2001年 | 23篇 |
2000年 | 18篇 |
1999年 | 17篇 |
1998年 | 14篇 |
1997年 | 20篇 |
1996年 | 9篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1970年 | 7篇 |
1968年 | 4篇 |
1966年 | 3篇 |
排序方式: 共有923条查询结果,搜索用时 31 毫秒
1.
Based on its proven anabolic effects on bone in osteoporosis patients, recombinant parathyroid hormone (PTH1-34) has been evaluated as a potential therapy for skeletal repair. In animals, the effect of PTH1-34 has been investigated in various skeletal repair models such as fractures, allografting, spinal arthrodesis and distraction
osteogenesis. These studies have demonstrated that intermittent PTH1-34 treatment enhances and accelerates the skeletal repair process via a number of mechanisms, which include effects on mesenchymal
stem cells, angiogenesis, chondrogenesis, bone formation and resorption. Furthermore, PTH1-34 has been shown to enhance bone repair in challenged animal models of aging, inflammatory arthritis and glucocorticoid-induced
bone loss. This pre-clinical success has led to off-label clinical use and a number of case reports documenting PTH1-34 treatment of delayed-unions and non-unions have been published. Although a recently completed phase 2 clinical trial of PTH1-34 treatment of patients with radius fracture has failed to achieve its primary outcome, largely because of effective healing
in the placebo group, several secondary outcomes are statistically significant, highlighting important issues concerning the
appropriate patient population for PTH1-34 therapy in skeletal repair. Here, we review our current knowledge of the effects of PTH1-34 therapy for bone healing, enumerate several critical unresolved issues (e.g., appropriate dosing regimen and indications)
and discuss the long-term potential of this drug as an adjuvant for endogenous tissue engineering. 相似文献
2.
Jill S. Marty James P. Higham Elizabeth L. Gadsby Caroline Ross 《International journal of primatology》2009,30(6):807-823
Sexual selection has driven the evolution and elaboration of a wide variety of displays and ornaments in male nonhuman primates,
including capes, cheek flanges, and sexual coloration. Among the most sexually dimorphic of all primates is the drill (Mandrillus leucophaeus), the males of which can be 3 times the mass of females, possess large canines, and exhibit extremely bright sexual skin
coloration. However, the function of male coloration in this species has never been examined. Here, we present data on male
color (measured objectively using digital photography), dominance rank, measures of male-female association, and key sexual
behaviors, of adult male drills (n = 17) living in four semi free-ranging enclosures at the Drill Rehabilitation and Breeding Center in Nigeria. We test the
hypothesis that male coloration is a badge of status, indicating dominance rank, and the hypothesis that male coloration attracts
females. We found that male coloration did indicate rank, and that high ranking, strongly colored males were more likely to
associate with adult females, and more specifically with fully tumescent females. These males also engaged in more sexual
activity. However, measures of male-female association and sexual behaviors were not related to male color once rank had been
taken into consideration; i.e., for males of a given rank, females did not prefer those that were more colorful. We discuss
the results in light of what is known about the wild drill social system, in which unfamiliar individuals may come together
in “supergroups,” and in which quality indicators of competitive ability may be particularly important. 相似文献
3.
Role of RNA structures in c-myc and c-fos gene regulations 总被引:1,自引:0,他引:1
4.
The addition of antimycin A during the logarithmic phase of growth of heterotrophic Euglena gracilis cultures (in lactate or glucose medium) was immediately followed by decreased respiration and a cessation of grwoth. Induced cyanideresistent respiration appeared 5 h after the addition of the inhibitor then the cells started to grow again and could be cultured in the presence of antimycin A. Thus the cells exhibited a cyanide-and antimycin-resistant respiration which was, in addition, sensitive to salicylhydroxamic acid and propylgallate. Antimycin-adapted Euglena and control cells were compared for their biomass production and protein synthesis. The difference in growth yield between control and antimycin-adapted cells was not as high as would be expected if only the first phosphorylation site of the normal respiratory chain was active in the presence of antimycin A. Furthermore, the ability to incorporate labelled valine into proteins, under resting-cell conditions, was not changed. Strong correlations were established between the effects of respiratory effectors on O2 consumption and valine incorporation. These results suggest that sufficient energy for protein synthesis and growth is provided by the operation of the cyanide-resistant respiratory pathway in antimycin-adapted Euglena.Abbreviations DNP
dinitrophenol
- PG
propylgallate
- SHAM
salicylhydroxamic acid 相似文献
5.
Danielle G. Marty 《Biotechnology letters》1985,7(12):900-904
Summary Study of CMC fermentation by a marine syntrophic association of an anaerobic cellulose-degrader, a carbohydrate-fermenter, and a methanogen. Altered fermentation pattern in general agreement with the concept of interspecies hydrogen transfer was obtained only with pregrowth of methanogen followed by inoculation of the two fermentative bacteria. 相似文献
6.
Summary We have used response surface methodology to study the interactions between various parameters (pH, temperature, enzyme concentration) controlling the immobilization of ribonuclease A on to glutaraldehyde activated-amine Spherosil beads. The optimum activity of immobilized ribonuclease A was observed at pH=9.1. The specific activity of the immobilized enzyme was affected by the pH and by the enzyme concentration. 相似文献
7.
Tom Strachan Alan B. Dodge David Smillie Philip A. Dyer Regis Sodoyer Bertrand R. Jordan Rodney Harris 《Immunogenetics》1986,23(2):115-120
Analysis of available nucleotide sequence data for class I HLA genes has established that the seventh intron is one of the gene regions which expresses the highest degree of locus specificity (the percentage sequence divergence between nonallelic genes minus the percentage sequence divergence between allelic genes). We have subcloned short DNA sequences including this region from the HLA-Cw3 gene. Two clones, pC250 and pC800, were tested by hybridizing them at high stringency to a panel of clones containing class I HLA genes. Under conditions permitting a strong hybridization signal with a C-locus gene, pC800 also expressed a weak but significant hybridization to other class I genes, while pC250 appeared to hybridize exclusively to the C-locus gene. Hybridization of the pC250 probe at high stringency to Hind III-digested genomic DNA from a panel of unrelated individuals and homozygous typing cell lines revealed a single band in all cases. However, equivalent hybridization against Eco RI-digested DNA revealed two hybridization bands, one at 7.9 kb which correlated with the serologically defined Cw5 and Cw8 alleles, and one at 7.6 kb which correlated with the Cw1, Cw2, Cw3, Cw4, Cw6, and Cw7 alleles. 相似文献
8.
9.
10.
Sophie Seigneurin-Venin Elaine Parrish Isabelle Marty François Rieger Georges Romey Michel Villaz Luis Garcia 《Experimental cell research》1996,223(2):301
The process of myoblast fusion during skeletal myogenesis is calcium regulated. Both dihydropyridine receptor and ryanodine receptor are already present on muscle precursors, at the prefusional stage, before they are required for excitation–contraction coupling. Previous pharmacological studies have shown the need for a special pool of Ca2+associated with the membrane for the fusion process to occur. We hypothesized that this pool of Ca2+is mobilized via a machinery similar to that involved in excitation–contraction coupling. The process of fusion in rat L6 muscle precursors was either totally or partially abolished in the presence of the L-type calcium channel inhibitors SR33557 and nifedipine (half inhibition towards 2 μM), respectively. The inhibition was reversible and dose-dependent. Drugs able to deplete internal calcium stores (caffeine, ryanodine, and thapsigargin) were also tested on the fusion. Both caffeine and thapsigargin drastically inhibited fusion whereas ryanodine had no effect. This suggests that fusion may be controlled by internal pools of Ca2+but that its regulation may be insensitive to ryanodine. We presumed that an early form of the ryanodine receptor may exist, with different pharmacological properties than the adult forms. Indeed, Western blot analysis of pre- and postfusional L6 cells demonstrated the presence, at the prefusional stage, of a transient form of the ryanodine receptor protein with an apparent molecular weight slightly different from those of the classical skeletal and cardiac forms. Taken together, these results support the hypothesis that the fusion process is driven by a mechanism involving both the dihydropyridine receptor (α1 subunit of the L-type Ca2+channel) and the internal stores of Ca2+. The machinery underlying this mechanism might consist of slightly different forms of the classic molecules that in adult muscle ensure excitation–contraction coupling. It remains to be seen, however, whether the mobilization of the internal pool of Ca2+is triggered by the type of mechanism already described in skeletal muscle. 相似文献