全文获取类型
收费全文 | 141篇 |
免费 | 18篇 |
专业分类
159篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 5篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 1篇 |
2008年 | 4篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 5篇 |
1968年 | 3篇 |
1967年 | 5篇 |
1963年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有159条查询结果,搜索用时 0 毫秒
61.
DNA ligase IV mutations identified in patients exhibiting developmental delay and immunodeficiency. 总被引:11,自引:0,他引:11
M O'Driscoll K M Cerosaletti P M Girard Y Dai M Stumm B Kysela B Hirsch A Gennery S E Palmer J Seidel R A Gatti R Varon M A Oettinger H Neitzel P A Jeggo P Concannon 《Molecular cell》2001,8(6):1175-1185
DNA ligase IV functions in DNA nonhomologous end-joining and V(D)J recombination. Four patients with features including immunodeficiency and developmental and growth delay were found to have mutations in the gene encoding DNA ligase IV (LIG4). Their clinical phenotype closely resembles the DNA damage response disorder, Nijmegen breakage syndrome (NBS). Some of the mutations identified in the patients directly disrupt the ligase domain while others impair the interaction between DNA ligase IV and Xrcc-4. Cell lines from the patients show pronounced radiosensitivity. Unlike NBS cell lines, they show normal cell cycle checkpoint responses but impaired DNA double-strand break rejoining. An unexpected V(D)J recombination phenotype is observed involving a small decrease in rejoining frequency coupled with elevated imprecision at signal junctions. 相似文献
62.
GIRK (Kir3) channels are activated by neurotransmitters coupled to G proteins, via a direct binding of G(beta)(gamma). The role of G(alpha) subunits in GIRK gating is elusive. Here we demonstrate that G(alpha)(i) is not only a donor of G(beta)(gamma) but also regulates GIRK gating. When overexpressed in Xenopus oocytes, GIRK channels show excessive basal activity and poor activation by agonist or G(beta)(gamma). Coexpression of G(alpha)(i3) or G(alpha)(i1) restores the correct gating parameters. G(alpha)(i) acts neither as a pure G(beta)(gamma) scavenger nor as an allosteric cofactor for G(beta)(gamma). It inhibits only the basal activity without interfering with G(beta)(gamma)-induced response. Thus, GIRK is regulated, in distinct ways, by both arms of the G protein. G(alpha)(i) probably acts in its GDP bound form, alone or as a part of G(alpha)(beta)(gamma) heterotrimer. 相似文献
63.
M. J. Navarro-Lozano E. Valero R. Varon F. Garcia-Carmona 《Bulletin of mathematical biology》1995,57(1):157-168
In the present paper a kinetic study is made of the behaviour of a Michaelis-Menten enzyme-catalysed reaction in the presence
of irreversible inhibitors rendered unstable in the medium by their reaction with the product of enzymatic catalysis. A general
mechanism involving competitive, non-competitive, uncompetitive and mixed irreversible inhibition with one or two steps has
been analysed. The differential equation that describes the kinetics of the reaction is non-linear and computer simulations
of its dynamic behaviour are presented. The results obtained show that the systems studied here present kinetic co-operativity
for a target enzyme that follows the simple Michaelis-Menten mechanism in its action on the substrate, except in the case
of an uncompetitive-type inhibitor. 相似文献
64.
65.
66.
Isolation of Host-Dependent and Nonparasitic Mutants of the Facultative Parasitic Bdellovibrio UKi2 总被引:1,自引:1,他引:0
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)
Obligate host-dependent and nonparasitic mutants were isolated from a facultative parasitic Bdellovibrio strain. Thus it is possible to separate host-dependency from the ability to parasitize in bdellovibrios. 相似文献
67.
—Intact and dissociated dorsal root ganglia from 8-day chick embryos were examined for their ability to incorporate radio-precursors into RNA and protein in unsupplemented medium or in medium supplemented with Nerve Growth Factor, insulin, Concanavalin A, fetal calf serum, or several combinations of such agents. In the absence of any agent, incorporation into RNA and protein declined with time. All four agents maintained or improved the initial incorporation rates, and optimal doses were determined in each case. Different combinations of two agents led to potentiated, full or partially additive, or inhibited effects; in particular, NGF promoted incorporation even in conjunction with insulin (additive) or serum (potentiating). Several differences were noted between the responses of intact and of dissociated ganglia. 相似文献
68.
Elongation and division of Bdellovibrio bacteriovorus were studied in axenic synchronous cultures. The cells elongate unidirectionally from one end attaining a length of several unit cells, and then divide into the corresponding number of cells. The length of the filament and, consequently, the progeny number, vary within the range of two to several dozen cells, according to the conditions used. A protein and a low molecular weight component are required for normal division. 相似文献
69.
Jean-Louis?Koeck Berthe-Marie?Njanpop-Lafourcade Sonia?Cade Emmanuelle?Varon Lassana?Sangare Samina?Valjevac Gilles?Vergnaud Christine?PourcelEmail author 《BMC microbiology》2005,5(1):66
Background
Precise identification of bacterial pathogens at the strain level is essential for epidemiological purposes. InStreptococcus pneumoniae, the existence of 90 different serotypes makes the typing particularly difficult and requires the use of highly informative tools. Available methods are relatively expensive and cannot be used for large-scale or routine typing of any new isolate. We explore here the potential of MLVA (Multiple Loci VNTR Analysis; VNTR, Variable Number of Tandem Repeats), a method of growing importance in the field of molecular epidemiology, for genotyping ofStreptococcus pneumoniae. 相似文献70.
M. Macek Jr. Milan Macek Sr. Alice Krebsová E. Nash A. Hamosh André Reis Raymonda Varon-Mateeva Nancy E. Maestri Karl Sperling Michael Krawczak G. R. Cutting J. Schmidke 《Human genetics》1997,99(5):565-572
Cystic fibrosis (CF) patients show a high degree of linkage disequilibrium between the CF transmembrane conductance regulator
(CFTR) gene and polymorphisms 5′ of that gene. To determine whether the region 5′ of CFTR contains biologically important sequences, the allele frequencies of six CFTR-linked polymorphisms (metH/MspI, XV-2c/TaqI, CS.7/HhaI, KM19/PstI, MP6-d9/MspI, J44/XbaI) were determined in 417 randomly selected elderly individuals (over 75 years of age) from the Czech population. The elderly
individuals were considered “escapees” of strong selective pressures that had operated during their lifetime, prior to the
introduction of modern health care since 1950. The pooled allele frequencies of the analyzed marker polymorphisms in the elderly
did not significantly differ from published data. However, when analyzed by sex, the allele frequencies of markers CS.7/HhaI and KM19/PstI differed significantly (P < 0.05) between elderly females and males. The allele frequencies of the six polymorphisms were then determined in 646 newborns
and 345 young adults of reproductive age; these individuals were selected in a similar manner and drawn from the same population.
In these control groups, the studied marker polymorphisms exhibited no statistically significant differences between sexes
and/or between individuals of the same sex, only between different age groups. A gradual relative increase in the frequency
of allele “2” of marker CS.7/HhaI was observed from newborn females to elderly women, the overall difference in allele frequencies of this marker polymorphism
between newborn females and elderly women reaching statistical significance (P < 0.05). Interestingly, allele “2” is the major constituent of the extended “B-haplotype”, which is in strong linkage disequilibrium
with common CF alleles. Taken together, our data suggest that the region spanning markers CS.7 and KM19 is associated with
a genetic factor that influences postnatal female survival, providing a possible mechanism for increasing the frequency of
particular mutations in the adjacent CFTR gene.
Received: 30 January 1996 / Revised: 16 December 1996 相似文献