全文获取类型
收费全文 | 245篇 |
免费 | 38篇 |
国内免费 | 1篇 |
出版年
2022年 | 4篇 |
2021年 | 5篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2017年 | 2篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 8篇 |
2012年 | 17篇 |
2011年 | 11篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 7篇 |
2007年 | 8篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 11篇 |
1999年 | 13篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 7篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
排序方式: 共有284条查询结果,搜索用时 31 毫秒
1.
2.
The growth rate of the hybridoma cell line ATCC-CRL-1606 in low serum medium declines rapidly with time after inoculation. To characterize this phenomenon, the stability of the growth-promoting activity of serum was investigated. The activity of serum was found to de grade with time, and was stabilized by alterations in the medium formulation that acted to lower the oxidation/reduction potential. This included both the addition of thiols and the elimination of disulfides from the medium. Additionally, cysteine and other thiols were shown to stimulate growth in low serum, low cell density cultures, suggesting that thiols may be rate-limiting in low serum medium. Stimulation of growth by thiol addition was less significant at high cell levels, implying that the cells themselves may be acting to reduce their environment. A hypothesis is presented based on these results which suggests that the actual rate-limiting moieties in low serum cultures may be dithiols. 相似文献
3.
4.
C. A. Batt M. T. Follettie H. K. Shin P. Yeh A. J. Sinskey 《Trends in biotechnology》1985,3(12):305-310
The coryneforms are a diverse group of bacteria which includes animal and plant pathogens as well as non-pathogenic bacteria. Although they are of significant economic and health importance, their genetics is poorly understood. The development of genetic engineering techniques for coryneforms and initial gene cloning studies are discussed. 相似文献
5.
6.
Transformation of T lymphocytes by the v-fos oncogene 总被引:4,自引:0,他引:4
V E Valge-Archer J de Villiers A J Sinskey A Rao 《Journal of immunology (Baltimore, Md. : 1950)》1990,145(12):4355-4364
Activation of T lymphocytes through the T cell antigen receptor has been shown to stimulate a rapid and transient accumulation of c-fos mRNA and protein. Transfection of a normal murine T lymphocyte clone with the FBJ-v-fos oncogene resulted in generation of a cell line that was morphologically transformed, had lost the requirement for IL-2 for proliferation, and was tumorigenic in adult syngeneic mice; however, the transformed cells retained the ability to proliferate in response to IL-2. The transformed cells did not show constitutive expression of IL-2 or c-fos mRNA, although the promoter regions of both IL-2 and c-fos genes contain AP-1 sites that are expected to be targets for binding of Fos/Jun complexes. In contrast, the transformed T cells showed increased constitutive expression of IL-2R alpha and c-myc mRNA; these genes may represent cellular targets for transformation by v-fos and physiologic activation by c-fos. We discuss the possibility that these transformed cells behave as cells partially activated through the TCR, and that transformation occurs through a mechanism independent of IL-2. 相似文献
7.
Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews
(genus Sorex) for the region between the tRNA(Pro) and the conserved
sequence block-F revealed variable numbers of 79-bp tandem repeats. These
repeats were found in all 19 individuals sequenced, representing three
subspecies and one closely related species of the masked shrew group (Sorex
cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an
outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an
adjacent 76-bp imperfect copy of the tandem repeats. One individual was
heteroplasmic for length variants consisting of five and seven copies of
the 79-bp tandem repeat. The sequence of the repeats is conducive to the
formation of secondary structure. A termination-associated sequence is
present in each of the repeats and in a unique sequence region 5' to the
tandem array as well. Mean genetic distance between the masked shrew taxa
and the pygmy shrew was calculated separately for the unique sequence
region, one of the tandem repeats, the imperfect repeat, and these three
regions combined. The unique sequence region evolved more rapidly than the
tandem repeats or the imperfect repeat. The small genetic distance between
pairs of tandem repeats within an individual is consistent with a model of
concerted evolution. Repeats are apparently duplicated and lost at a high
rate, which tends to homogenize the tandem array. The rate of D- loop
sequence divergence between the masked and pygmy shrews is estimated to be
15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid
sequence evolution in shrews may be due either to their high metabolic rate
and short generation time or to the presence of variable numbers of tandem
repeats.
相似文献
8.
The relationship between synthesis and N-liked glycosylation site occupancy of recombinant human prolactin produced from C127 cells was studied with the aid of a battery of protein synthesis inhibitors. Non-lethal concentrations of sodium fluoride, gougerotin, puromycin, anisomycin, and emetine did not alter site occupancy, but low concentrations (<10g ml–1) of cycloheximide increased the fraction of secreted prolactin bearing oligosaccharide from 20% to 80% of the total. Cycloheximide is an inhibitor of the elongation step of protein synthesis. The observed increase in glycosylation site occupancy upon addition of cycloheximide is consistent with the current opinion that the initial glycosylation event occurs cotranslationally during a limited time period. Cycloheximide may extend this time period by reducing elongation rate. However, the absence of any effect from treatment with other inhibitors of elongation suggests that cycloheximide is unique in its behavior on this system.Abbreviations clp-PRL
clipped form of prolactin
- DMEM/F12
11 Dulbecco's Modified Eagle's Medium/Ham's nutrient mixture F12
- G-PRL
glycosylated (N-linked) fraction of prolaction
- NG-PRL
prolactin fraction without N-linked glycosylation
- PMSF
phenylmethylsulfonylfluoride 相似文献
9.
10.
大鼠胼胝体内神经肽Y免疫反应阳性纤维的发育 总被引:1,自引:0,他引:1
本实验用免疫组织化学ABC法研究了大鼠胼胝体内神经肽Y免疫反应阳性(NPY-IR)纤维的生后发育。结果发现,许多NPY-IR纤维在大鼠出生时便存在于胼胝体内。NPY-IR胼胝体纤维的密度在生后1周内继续逐渐增高,在第2周内达到最高峰。之后,NPY-IR胼胝体纤维的密度逐渐下降,至第3周末时接近成年时的水平,即仅有少量NPY-IR纤维存在于胼胝体内。这些结果提示在大鼠早期生后发育过程中许多NPY-IR胼胝体纤维是暂时性的,其作用可能与大脑皮质的机能发育有关。 相似文献