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61.
Invasive species can displace natives, and thus identifying the traits that make aliens successful is crucial for predicting and preventing biodiversity loss. Pathogens may play an important role in the invasive process, facilitating colonization of their hosts in new continents and islands. According to the Novel Weapon Hypothesis, colonizers may out-compete local native species by bringing with them novel pathogens to which native species are not adapted. In contrast, the Enemy Release Hypothesis suggests that flourishing colonizers are successful because they have left their pathogens behind. To assess the role of avian malaria and related haemosporidian parasites in the global spread of a common invasive bird, we examined the prevalence and genetic diversity of haemosporidian parasites (order Haemosporida, genera Plasmodium and Haemoproteus) infecting house sparrows (Passer domesticus). We sampled house sparrows (N = 1820) from 58 locations on 6 continents. All the samples were tested using PCR-based methods; blood films from the PCR-positive birds were examined microscopically to identify parasite species. The results show that haemosporidian parasites in the house sparrows'' native range are replaced by species from local host-generalist parasite fauna in the alien environments of North and South America. Furthermore, sparrows in colonized regions displayed a lower diversity and prevalence of parasite infections. Because the house sparrow lost its native parasites when colonizing the American continents, the release from these natural enemies may have facilitated its invasion in the last two centuries. Our findings therefore reject the Novel Weapon Hypothesis and are concordant with the Enemy Release Hypothesis.  相似文献   
62.
Behçet's disease (BD) is a chronic multisystem disorder. Infectious agents, immune system mechanisms, and genetic factors are implicated in the etiopathogenesis of BD, which remains to be explained. The human MDR1 (ABCB1) gene encoder P-glycoprotein (P-gp) plays a key role in drug disposition, serves as a protective mechanism against xenobiotics, and provides additional protection for the brain, testis, and fetus. We investigated the genotype and haplotype distributions of three MDR1 gene polymorphisms (C1236T, G2677T/A, and C3435T) in 104 BD patients and 130 control subjects. The genotyping analysis was performed by using PCR–RFLP methods.  相似文献   
63.

Aim

The programmed cell death-1 (PD-1) is a potent immunoregulatory molecule which is responsible for the negative regulation of T-cell activation and peripheral tolerance. Recently, overexpression of PD-1 has been reported to contribute to immune system evasion and poor survival of hepatocellular carcinoma (HCC). A common single nucleotide polymorphism in intron 4 of PD-1 gene called PD-1.3 has been reported to influence PD-1 expression, but its association with HCC has yet to be investigated. The aim of the present study was to investigate whether this polymorphism could be involved in the risk of HCC susceptibility.

Methods

The genotype frequency of PD-1.3 polymorphism was determined by using a polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) method in 236 subjects with HCC and 236 cancer-free control subjects matched on age, gender, smoking and alcohol status.

Results

No statistically significant differences were found in the genotype distributions of the PD-1.3 polymorphism among HCC and cancer-free control subjects (P = 0.22).

Conclusion

Our results demonstrate for the first time that the PD-1.3 polymorphism has not been in any major role in genetic susceptibility to hepatocellular carcinogenesis, at least in the population studied here. Independent studies are needed to validate our findings in a larger series, as well as in patients of different ethnic origins.  相似文献   
64.
The presence of liver disease in patients with progressively worsening insulin resistance may not be recognized until patients develop manifestations of the metabolic syndrome such as diabetes, hypertension, hyperlipidemia, and vascular disease. It was aimed to investigate whether three angiotensin II type 1 receptor antagonists (ARBs) (olmesartan, losartan, and valsartan) had preventive effect against hepatic fibrosis and this was a common characteristic among ARBs. In current study, 25 adult male rats were used and divided into five groups: the non-diabetic healthy group, alloxan induced diabetic (AID) control group, AID losartan group, AID valsartan group and AID olmesartan group. According to numerical density of hepatocytes, significant difference was found between the non-diabetic healthy group and diabetic control group. All treatments groups were significant when compared to diabetic control group. In diabetic control group it was examined swelling, irregular cristae arrangement in some of mitochondria. It was also determined mitochondria membrane degeneration in some areas of section profiles. In diabetic rats treated with losartan group, there were necrotic hepatocytes. In diabetic rats treated with valsartan group, predominantly, findings were similar to losartan group. In diabetic rats treated with olmesertan group, plates of hepatocytes were quite regular. There were hardly necrotic cells. Not only other organelles such as RER, SER and lysosom but also mitochondrial structures had normal appearance. In the diabetic control group electron microscopy revealed edema in both the cytoplasm and perinuclear area and the nuclear membranes appeared damaged. In conclusion, it was established that the most protective ARB the liver in diabetic rats was olmesartan, followed by losartan.  相似文献   
65.
Background: Tumor necrosis factor-α (TNF-α) is a pro-inflammatory cytokine that may act as an endogenous tumor promoter. A genetic polymorphism of TNF-α gene at position ?308 promoter region is involved in the regulation of expression level and has been found to be associated with susceptibility to various types of cancer. Methods: To determine the association of the TNF-α gene G-308A polymorphism on the risk of hepatocellular carcinoma (HCC) in a Turkish population, a hospital-based case-control study was designed consisting of 110 diagnosis subjects with hepatocellular carcinoma and 110 cancer-free control subjects matched on age, gender, smoking and alcohol status. The genotype frequency of this polymorphism was determined by using a polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) assay. Results: The distribution G-308A genotype was significantly associated with the risk of HCC (p < 0.001, odds ratio [OR] = 4.75, 95% confidence interval [CI] = 2.25–9.82 for ?308 AA/GA genotypes versus GG genotype). Conclusion: We suggested that the presence of the high producer allele ?308A in the TNF-α gene appears to be associated with an increased risk for the development of HCC in Turkish population.  相似文献   
66.
Pectinesterase (PE) in Malatya apricot pulp (Prunus armeniaca L.) was extracted and purified through (NH(4))(2)SO(4) precipitation, dialysis, and DEAE-Sephadex gel filtration chromatography. The samples obtained from the dialysis procedure, named partially purified enzyme, were used for characterization of the apricot pectinesterase. The effect of various factors such as pH, temperature, heat, and storage stability on the partially purified apricot PE enzyme was investigated. Optimum pH value was 9.0 for PE with 1% pectin in 0.1 N NaCl (w/v). The optimum temperature for apricot PE was found to be 60 degrees C on standard analysis conditions. Heat inactivation studies showed a decrease in enzymatic activity at temperatures above 70 degrees C. Km and V(max) values were 0.77 mM and 1.75 micromol min(-1) mg(-1) for apricot PE. Five inhibitors were tested in the study; the most effective inhibitor was found to be sodium carbonate (100% inhibition). The order of inhibitory effectiveness was: Na(2)CO(3), iodine, lauril sulphate, AgNO(3), EDTA. Thermal inactivation data indicated that apparent activation energy with pectin substrate was 2.96 kcal mol(-1) for the enzyme. Ascorbic acid, CaCl(2), and KCl showed activatory effect on the apricot PE enzyme.  相似文献   
67.
We describe a novel genetic screen that is performed by transfecting every individual clone of an expression library into a separate population of cells in a high-throughput mode. The screen allows one to achieve a hitherto unattained sensitivity in expression cloning which was exploited in a first read-out to clone apoptosis-inducing genes. This led to the isolation of several genes whose proteins induce distinct phenotypes of apoptosis in 293T cells. One of the isolated genes is the tumor suppressor cytochrome b(L) (cybL), a component of the respiratory chain complex II, that diminishes the activity of this complex for apoptosis induction. This gene is more efficient and specific for causing cell death than a drug with the same activity. These results suggest further applications, both of the isolated genes and the screen.  相似文献   
68.
Plant Cell, Tissue and Organ Culture (PCTOC) - An efficient in vitro mass propagation through protocorm-like bodies (PLBs) was established in Cattleya forbesii Lindl., a commercially important...  相似文献   
69.
70.
Abstract

Pectinesterase (PE) in Malatya apricot pulp (Prunus armeniaca L.) was extracted and purified through (NH4)2SO4 precipitation, dialysis, and DEAE-Sephadex gel filtration chromatography. The samples obtained from the dialysis procedure, named partially purified enzyme, were used for characterization of the apricot pectinesterase. The effect of various factors such as pH, temperature, heat, and storage stability on the partially purified apricot PE enzyme was investigated. Optimum pH value was 9.0 for PE with 1% pectin in 0.1 N NaCl (w/v). The optimum temperature for apricot PE was found to be 60°C on standard analysis conditions. Heat inactivation studies showed a decrease in enzymatic activity at temperatures above 70°C. Km and Vmax values were 0.77 mM and 1.75 µmol min?1 mg?1 for apricot PE. Five inhibitors were tested in the study; the most effective inhibitor was found to be sodium carbonate (100% inhibition). The order of inhibitory effectiveness was: Na2CO3, iodine, lauril sulphate, AgNO3, EDTA. Thermal inactivation data indicated that apparent activation energy with pectin substrate was 2.96 kcal mol?1 for the enzyme. Ascorbic acid, CaCl2, and KCl showed activatory effect on the apricot PE enzyme.  相似文献   
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