全文获取类型
收费全文 | 554篇 |
免费 | 45篇 |
出版年
2022年 | 3篇 |
2021年 | 14篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 16篇 |
2013年 | 27篇 |
2012年 | 23篇 |
2011年 | 38篇 |
2010年 | 16篇 |
2009年 | 14篇 |
2008年 | 23篇 |
2007年 | 24篇 |
2006年 | 24篇 |
2005年 | 25篇 |
2004年 | 26篇 |
2003年 | 18篇 |
2002年 | 21篇 |
2001年 | 23篇 |
2000年 | 21篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 4篇 |
1969年 | 2篇 |
1968年 | 3篇 |
排序方式: 共有599条查询结果,搜索用时 272 毫秒
11.
G. Arpaia J. J. Loros J. C. Dunlap G. Morelli G. Macino 《Molecular genetics and genomics : MGG》1995,247(2):157-163
Ambient light and the circadian clock have been shown to be capable of acting either independently or in an interrelated fashion to regulate the expression of conidiation in the ascomycete fungusNeurospora crassa. Recently several molecular correlates of the circadian clock have been identified in the form of the morning-specific clock-controlled genesccg-1 andccg-2. In this paper we report studies on the regulation ofccg-1, an abundantly expressed gene displaying complex regulation. Consistent with an emerging consensus for clock-controlled genes and conidiation genes inNeurospora, we report thatccg-1 expression is induced by light, and show that this induction is independent of the direct effects of light on the circadian clock. Although circadian regulation of the gene is lost in strains lacking a functional clock, expression ofccg-1 is still not constitutive, but rather fluctuates in concert with changes in developmental potential seen in such strains. Light induction ofccg-1 requires the products of theNeurospora wc-1 andwc-2 genes, but surprisingly the requirement forwc-2 is suppressed in conditional mutants ofcot-1, a gene that encodes a cAMP-dependent protein kinase. These data provide insight into a complex regulatory web, involving at least circadian clock control, light control, metabolic control, and very probably developmental regulation, that governs the expression ofccg-1. 相似文献
12.
Biphasic Stimulation of Translational Activity Correlates with Induction of Translation Elongation Factor 1 Subunit [alpha] upon Wounding in Potato Tubers 总被引:4,自引:2,他引:2
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Potato (Solanum tuberosum) tubers exhibit an increase in translational activity in response to mechanical wounding. The response is biphasic, with an initial stimulation apparent within the first 2 h after wounding and a second increase occurring 12 to 24 h after wounding. Increased activity is apparent by measurement of protein synthesis both in vivo and in vitro using a cell-free extract. Accumulation of the translational elongation factor 1 subunit [alpha] (EF-1[alpha]) parallels translational activity. Changes in the steady-state level of EF-1[alpha] mRNA, and expression of a chimeric EF-1[alpha] promoter/[beta]-glucuronidase construct in transgenic potato tubers, indicate that the gene encoding EF-1[alpha] is transcribed during both periods of translational stimulation. These results indicate that stimulation of translational activity is coordinated with increased expression and accumulation of translation factors. 相似文献
13.
Daniele Morelli Alessandro Sardini Elena Villa Maria Luisa Villa Sylvie Ménard Maria I. Colnaghi Andrea Balsari 《Cancer immunology, immunotherapy : CII》1994,38(3):171-177
A hybrid hybridoma secreting a bispecific hybrid mAb (bsmAb), which recognizes both the epidermal growth factor receptor (EGF-R) and the drug doxorubicin, was produced by somatic hybridization of two hybridomas. The bsmAb obtained was able to retarget doxorubicin cytotoxicity in vitro specifically on EGF-R-positive cells exerting at the same time an antidotal effect on cells that did not overexpress the EGF-R. Distribution studies in mice indicate that the bsmAb selectively delivers the drug to tumour cells and modifies doxorubicin biodistribution with a statistically significant decrease of drug concentration in the intestine, which is the main target of early anthracycline toxicity. In keeping with this finding is the remarkable antidotal activity exerted by bsmAb in mice treated with doxorubiein, which is proved by retardation in loss of body weight and mortality. The effectiveness on tumour growth of the mAb followed by the administration of doxorubicin appears to be equal to that of the drug alone; however, the bsmAb exerts a remarkable antidotal activity. 相似文献
14.
Field observations on the biology ofMetriona elatior (Col.: Chrysomelidae) onSolanum elaeagnifolium (Solanaceae) from Uruguay.
Specimens ofMetriona elatior were found feeding on leaves of the silverleaf nightshade,Solanum elaeagnifolium, from the eastern of Uruguay since 1984. According to a field study the young leaves were skeletonized since spring to early
autumn by larvae and adults. Oothecae and pupae were found mainly on old leaves. The egg mean volume was of 0.614 mm3. Young plants of the weed were always killed after massive natural infections ofM. elatior. Therefore, this tortoise leaf-beetle may be studied as a potential biocontrol agent on populations ofS. elaeagnifolium.
相似文献
15.
R. Fattorusso G. Morelli A. Lombardi F. Nastri O. Maglio G. D'Auria C. Pedone V. Pavone 《Biopolymers》1995,37(6):401-410
Two cyclic and branched peptides (PLA and AZU) were synthesized with the aim of reproducing the active site of the blue copper proteins plastocyanin and azurin. Both peptides, designed on the basis of the x-ray structures of Poplar plastocyanin and Alcaligenes denitrificans azurin. contain the same coordinating residues of the parent native proteins. The visible spectra of PLA in the presence of equimolar amount of Cu(II) strongly support the interaction between the peptide and copper(II) ion. The CD titration of AZU with the Hg(II) ion indicates for the formation of two species. [A ZUHg]+ and [A ZUHg2]3+ having binding constants (Keq) of 3.106 and 2–104M?1, respectively. © 1994 John Wiley & Sons, Inc. 相似文献
16.
A monoclonal antibody extends the half-life of an anti-HIV oligodeoxynucleotide and targets it to CD4+ cells.
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
D Morelli B Pozzi J A Maier S Mnard M I Colnaghi A Balsari 《Nucleic acids research》1995,23(22):4603-4607
An approach was sought to increase the half-life and target cell specificity of antisense oligodeoxynucleotides (oligos). A monoclonal antibody (MAb) was derived from mice immunised with an oligo complementary to a region (1-20) of the HIV genome. This MAb exerts a protective effect on the oligo from the degradation induced by plasma exonucleases in vitro and in vivo. Moreover the anti-oligo MAb dissociates from the oligo in the presence of its complementary sequence to allow hybridization of the two complementary strands. To direct the oligo to CD4+ cells the anti-oligo MAb was cross-linked to an anti-CD4 MAb. The heteroaggregate determines a 5-fold increase in the cellular membrane binding of the oligo to CD4+ lymphocytes. These findings suggest a new approach to enhancing the therapeutic action and the target specificity of antisense oligodeoxynucleotides useful for the selective inhibition of HIV replication in vivo. 相似文献
17.
Summary A new variant of human erythrocyte glucose 6-phosphate dehydrogenase (G6PD), designated G6PD Cagliari, has been characterized. It is associated with severe enzyme deficiency and can be placed in Class 2 of the usual tabulation of G6PD variants. The specific activity of this variant is near normal, while its decay within the circulating erythrocytes is very rapid compared with normals. Genetic analysis of the family of the propositus indicated that the two available females are heterozygotes characterized by extremely unbalanced mosaic phenotypes. 相似文献
18.
The effect of GABA on in vitro binding of two novel non-benzodiazepines, PK 8165 and CGS 8216, to benzodiazepine receptors in the rat brain 总被引:1,自引:0,他引:1
The effect of gamma-aminobutyric acid (GABA) on the binding of PK 8165, a quinoline derivative, and CGS 8216, a pyrazoloquinoline, was assessed in two different regions of the rat brain. PK 8165, a compound with reported anxiolytic properties, inhibited [3H]-propyl beta-carboline-3-carboxylate labeled receptors in the cerebellum with an IC50 of 844 nM and 370 nM in the absence and presence of micro M GABA, respectively. GABA (100 micro M) was less effective in the cerebral cortex, decreasing the IC50 value from 280 to 197 nM. In saturation isotherm studies with [3H]-CGS 8216, a benzodiazepine receptor antagonist, GABA (100 micro M) induced a small but significant reduction in the apparent affinity of [3H]-CGS 8216 for benzodiazepine receptors in the cerebral cortex but the Bmax was unchanged. 相似文献
19.
Analysis of the promoter-distal region of the tra operon of the F sex factor of Escherichia coli K-12 encoded by EcoRI restriction fragments f17, f19, and f2. 总被引:12,自引:6,他引:6
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 promoter-distal region of the tra operon of the F sex factor Escherichia coli K-12 was analyzed, using the chimeric plasmid pRS31, which contains the F EcoRI restriction fragments f17, f19, and f2 cloned into the EcoRI site of pSC101. A series of deletion plasmids of pRS31, extending increasing distances from a site in f17 through f19 and ending in f2, were isolated. These plasmids were examined by heteroduplex analysis with the parent DNA, and a restriction map of this region of DNA was constructed. A series of Tn5 insertion derivatives of pRS31 were also isolated and mapped, using both heteroduplex analysis and restriction mapping. Both the insertion and deletion mutants were tested in minicells for the synthesis of radioactively labeled proteins. This allowed the identification of the individual gene products and mapping of the genes. The result is a saturated physical map of this region of DNA from fragment f17 through to the IS3 insertion sequence near the promoter-distal end of f2. 相似文献
20.
C Mangoni di S Stefano M Ruggiero M Brunese S Morelli 《Bollettino della Società italiana di biologia sperimentale》1979,55(14):1398-1404
Metabolic rate of obese patients is reported, recorded to cellular active mass. The metabolic rate is higher in obese patients and the value is diucthy related to individual actual weight. The dinamic-specific action of proteins is normal. 相似文献