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排序方式: 共有116条查询结果,搜索用时 265 毫秒
1.
G Escolar C Navarro J L Galmés L I Casanovas O Bulbena 《Prostaglandins, leukotrienes, and essential fatty acids》1989,38(1):49-53
We have tested the ability of zinc acexamate (ZAC) to prevent platelet-activating-factor (Paf) induced gastric damage in rats. Lesions were characterized by a vascular congestion affecting the entire mucosa, oedema, haemorrhage and frequent necrosis of the more superficial areas. The gastric damage appearing after Paf was accompanied by degranulation of gastric mast cells. Leukocytes were often seen at the submucosal level. Oral pretreatment with ZAC reduced in a dose-dependent manner both gastric damage and mast cell degranulation observed after Paf. ZAC administered orally at a dose of 100 mg kg-1 statistically inhibited (p less than 0.01) gastric damage and mast cell degranulation. ZAC did not affect the hypotension induced by Paf confirming that gastric damage and hypotension appearing in rats after Paf administration are two independent phenomena. The present findings indicate that the inhibitory effect of ZAC upon gastric lesions induced by Paf may be related to the different protective actions exhibited by this zinc compound in a wide variety of experimental models of gastric ulcer. 相似文献
2.
We have broadly defined the DNA regions regulating esterase6 activity in
several life stages and tissue types of D. melanogaster using P-
element-mediated transformation of constructs that contain the esterase6
coding region and deletions or substitutions in 5' or 3' flanking DNA.
Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and
the primary sequences regulating its activity lie between -171 and -25 bp
relative to the translation initiation site: deletion of these sequences
decrease activity approximately 20-fold. Hemolymph activity is also
modulated by four other DNA regions, three of which lie 5' and one of which
lies 3' of the coding region. Of these, two have positive and two have
negative effects, each of approximately twofold. Esterase6 activity is
present also in two male reproductive tract tissues; the ejaculatory bulb,
which is another ancestral activity site, and the ejaculatory duct, which
is a recently acquired site within the melanogaster species subgroup.
Activities in these tissues are at least in part independently regulated:
activity in the ejaculatory bulb is conferred by sequences between -273 and
-172 bp (threefold decrease when deleted), while activity in the
ejaculatory duct is conferred by more distal sequences between -844 and
-614 bp (fourfold decrease when deleted). The reproductive tract activity
is further modulated by two additional DNA regions, one in 5' DNA (-613 to
-284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to
+2731 bp; threefold decrease when deleted) that probably overlaps the
adjacent esteraseP gene. Collating these data with previous studies
suggests that expression of EST6 in the ancestral sites is mainly regulated
by conserved proximal sequences while more variable distal sequences
regulate expression in the acquired ejaculatory duct site.
相似文献
3.
Nucleotide variation at the hypervariable esterase 6 isozyme locus of Drosophila simulans 总被引:2,自引:0,他引:2
Esterase 6 (Est-6/EST6) is polymorphic in both Drosophila melanogaster and
D. simulans for two common allozyme forms, as well as for several other
less common variants. Parallel latitudinal clines in the frequencies of the
common EST6-F and EST6-S allozymes in these species have previously been
interpreted in terms of a shared amino acid polymorphism that distinguishes
the two variants and is subject to selection. Here we compare the sequences
of four D. simulans Est-6 isolates and show that overall estimates of
nucleotide heterozygosity in both coding and 5' flanking regions are more
than threefold higher than those obtained previously for this gene in D.
melanogaster. Nevertheless, the ratio of replacement to exon silent-site
polymorphism in D. simulans is less than the ratio of replacement to silent
divergence between D. simulans and D. melanogaster, which could be the
result of increased efficiency of selection against replacement
polymorphisms in D. simulans or to divergent selection between the two
species. We also find that the amino acid polymorphisms separating EST6- F
and EST6-S in D. simulans are not the same as those that separate these
allozymes in D. melanogaster, implying that the shared clines do not
reflect shared molecular targets for selection. All comparisons within and
between the two species reveal a remarkable paucity of variation in a
stretch of nearly 400 bp immediately 5' of the gene, indicative of strong
selective constraint to retain essential aspects of Est-6 promoter
function.
相似文献
4.
Claudia Palladino Verónica Briz José María Bellón Inês Bártolo Patrícia Carvalho Ricardo Camacho M. ángeles Mu?oz-Fernández Rui Bastos Rolanda Manuel José Casanovas Nuno Taveira 《PloS one》2013,8(12)
In Mozambique, the evaluation of retention in HIV care and ART programmes is limited. To assess rate and predictors of attrition (no retention in care) and HAART effectiveness in HIV-1 infected patients who pay for medication and laboratory testing in Mozambique, we conducted a multicenter survey of HIV-1-infected patients who started HAART during 2002–2006. Cox proportional hazard models were used to assess risk of attrition and of therapy failure. Overall, 142 patients from 16 healthcare centers located in the capital city Maputo were followed-up for 22.2 months (12.1–46.7). The retention rate was 75%, 48% and 37% after one, two and three years, respectively. Risk of attrition was lower in patients with higher baseline CD4 count (P = 0.022) and attending healthcare center 1 (HCC1) (P = 0.013). The proportion of individuals with CD4 count ≤200 cells/µL was 55% (78/142) at baseline and decreased to 6% (3/52) at 36 months. Among the patients with available VL, 86% (64/74) achieved undetectable VL levels. The rate of immunologic failure was 17.2% (95% CI: 12.6–22.9) per 100 person-years. Risk of failure was associated to higher baseline CD4 count (P = 0.002), likely reflecting low adherence levels, and decreased with baseline VL ≥10,000 copies/mL (P = 0.033). These results suggest that HAART can be effective in HIV-1 infected patients from Mozambique that pay for their medication and laboratory testing. Further studies are required to identify the causes for low retention rates in patients with low CD4 counts and to better understand the association between healthcare setting and attrition rate. 相似文献
5.
6.
Rod and cone photoreceptors project from the outer retinal surface into a
carbohydrate-rich interphotoreceptor matrix (IPM). Unique IPM
glycoconjugates are distributed around rods and cones. Wheat germ
agglutinin (WGA) strongly decorates the rod matrix domains and weakly
decorates the cone matrix domains. This study characterizes the major
WGA-binding glycoprotein in the human IPM, which we refer to as SPACR
(sialoprotein associated with cones and rods). SPACR, which has a molecular
weight of 147 kDa, was isolated and purified from the IPM by lectin
affinity chromatography. A polyclonal antibody to SPACR was prepared that
colocalizes in tissue preparations with WGA-binding domains in the IPM.
Sequential digestion of SPACR with N- and O- glycosidases results in a
systematic increase in electrophorectic mobility, indicating the presence
of both N- and O-linked glycoconjugates. Complete deglycosylation results
in a reduction in the relative molecular mass of SPACR by about 30%.
Analysis of lectin binding allowed us to identify some of the structural
characteristics of SPACR glycoconjugates. Treatment with neuraminidase
exposes Galbeta1- 3GalNAc disaccharide as indicated by positive peanut
agglutinin (PNA) staining, accompanied by the loss of WGA staining. Maackia
amurensis agglutinins (MAA-1 and MAA-2), specific for sialic acid in
alpha2-3 linkage to Gal, bind SPACR, while Sambucus nigra agglutinin (SNA),
specific for alpha2-6 linked sialic acid, does not, indicating that the
dominant glycoconjugate determinant on SPACR is the O-linked carbohydrate,
NeuAcalpha2-3Galbeta1-3GalNAc. The abundance of sialic acid in SPACR
suggests that this glycoprotein may contribute substantially to the
polyanionic nature of the IPM. The carbohydrate chains present on SPACR
could also provide sites for extensive crosslinking and participate in the
formation of the ordered IPM lattice that surrounds the elongate
photoreceptors projecting from the outer retinal surface.
相似文献
7.
The recent structure determinations of the mammalian effector enzyme adenylyl cyclase reveal the structure of its catalytic core, provide new insights into its catalytic mechanism and suggest how diverse signaling molecules regulate its activity. 相似文献
8.
David M. Alba Salvador Moyà‐Solà Assumpció Malgosa Isaac Casanovas‐Vilar Josep M. Robles Sergio Almécija Jordi Galindo Cheyenn Rotgers Juan Vicente Bertó Mengual 《American journal of physical anthropology》2010,141(1):52-75
Pliopithecus (Pliopithecus) canmatensis sp. nov. is described from several Late Aragonian localities from Abocador de Can Mata (ACM) in els Hostalets de Pierola (Vallès‐Penedès Basin, Catalonia, Spain), spanning from ~11.7 to 11.6 Ma (C5r.3r subchron), and being correlated to the MN8 (reference locality La Grive L3). The ACM remains display a pliopithecine dental morphology with well‐developed pliopithecine triangles on M/2 and M/3. This, together with other occlusal details, negates an attribution to the subgenus Epipliopithecus. Although slightly smaller, the ACM remains are most similar in size to comparable elements of P. piveteaui and P. antiquus. Several occlusal details (such as the greater development of the buccal cingulid in lower molars) and dental proportions (M/3 much longer than M/2), however, indicate greater similarities with P. antiquus from Sansan and La Grive. The ACM remains, however, differ from P. antiquus in dental proportions as well as occlusal morphology of the lower molars (including the less peripheral position of the protoconid and more medial position of the hypoconulid, the more mesial position of the buccal cuspids as compared to the lingual ones, the narrower but distinct mesial fovea, the higher trigonid, and the more extensive buccal cingulid, among others). These differences justify a taxonomic distinction at the species level of the ACM pliopithecid remains with respect to P. antiquus. Previous pliopithecid findings from the Vallès‐Penedès Basin, previously attributed to P. antiquus, are neither attributable to the latter species nor to the newly erected one. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
9.
10.
JG Hansen W Gao J Dupuis GT O’Connor W Tang M Kowgier A Sood SA Gharib LJ Palmer M Fornage SR Heckbert BM Psaty SL Booth SUNLIGHT Consortium Patricia A Cassano 《Respiratory research》2015,16(1)