In order to study the effect of Salix psammophila checkerboard sand barrier on the composition and characteristics of particle size quantitatively,the drifting sand dune(LS),the sand dune with sand barrier of two years(TS) and the sand dune with sand barrier of six years(SS) were studied.Samples were taken on different parts of sand dunes and in different layers of sand and on different positions of checkerboard sand barrier,and composition and characteristics of particle size were studied.The results can be seen as follows:(1) with the sand barrier setting time increases,the content of silt and clay increases and the content of fine sand deceases.The content of silt and clay of SS shows significant difference with the content of silt and clay of TS and LS,when there is no significant difference between TS and LS;There is no significant difference in the content of each particle size in the three sand layers of LS and TS,but the volume content of silt,clay and fine sand of 0-5cm of SS is different from the two other layers.(2),The rangeability of frequency distribution curve of SS is smaller than the rangeability of TS and LS.The order of average particle MZ,sorting coefficient δ,skewness SK and kurtosis KG of each sand dunes is SSTSLS,each particle parameters of SS are significant different from the two other sand dunes,and there is no significant difference between TS and LS,and the order of each particle parameters of each layers of SS and TS is 0-5cm5-10cm10-15cm,but the particle parameters of each layers of LS have no significant difference.(3) The content of silt and clay of SS and TS on the northwest and southeast corner of the checkerboard sand barrier is bigger than the content in the center of the checkerboard sand barrier,and each particle parameters in the center of the checkerboard sand barrier are smaller than the ones on the northwest and southeast corner.

In this paper Ulmus pumila populations in two habitats of fixed sand dunes and low land between dunes in the Otindag sandy land were targeted and, the spatial distribution patterns and the associations of different developmental stages of the populations by using point pattern analysis. The results showed that the whole population in sandy lands between dunes had a clumped distribution at the scales <10 m. The young trees and middle-aged trees had random spatial distributions at a greater scale,however the mature trees had a clumped distribution. The spatial associations between different developmental stages exhibited at a smaller scale. With increasing scales,the spatial association between different developmental stages turned to be feeble. The whole population on fixed sand dunes had a clumped distribution at a smaller scale. With increasing scales,the population tended to have random spatial distributions. The spatial association of middle-aged trees and mature trees was positively correlated with each other. The spatial associations of different developmental stages were weak.

The soil seed banks of different point positions at different locations in moving dune with Salix psammophila checkerboard sand barrier of seven years were studied.Results show that sand barrier could intercept plant seeds and supplement the soil sand banks.Species composition and density of the soil seed banks were different.Their descending order in horizontal distribution was the lower part,the upper part,the middle part,the top part of windward slope,and the density was 0 on leeward slope.In the vertical distribution they significantly decreased as the increase of soil depth.The declining order of the biodiversity index of the soil seed banks was the upper part,the lower part,the middle part and the top part of windward slope.Species composition of the soil seed banks is medium similarity,but high similarity in sand barrier on neighboring position and low similarity in sand barrier on spaced position.Species composition and density of the soil seed banks at different locations were different.The declining order of the spatial distribution of density along the wind(the five points A,B,C,D and E on the diagonal from the northwest corner to the southeast corner of the Salix psammophila checkerboard sand barrier) and perpendicular to the wind(the north and south borders inside the Salix psammophila checkerboard sand barrier) was the northwest corner of the sand barrier(A),the point at the quarter of the diagonal to the northwest corner(B),the midpoint of the north border inside the sand barrier(F),the southeast corner of the sand barrier(E),the midpoint of the south border inside the sand barrier(G),the point at the quarter of the diagonal to the southeast corner(D) and the midpoint of the diagonal(C).There were two greater density parts and two smaller density parts in sand barrier.Except for richness index of Margalet on different point positions,the order of other indices was the midpoint of the south border inside the sand barrier(G)>the northwest corner of the sand barrier(A)>the point at the quarter of the diagonal to the northwest corner(B)>the midpoint of the diagonal(C)>the southeast corner of the sand barrier(E)> the point at the quarter of the diagonal to the southeast corner(D)>the midpoint of the north border inside the sand barrier(F).The similarity coefficient of floristic composition of soil seed banks of different point positions changed greatly.The study could provide theoretical basis for vegetation restoration evaluation under the condition of sand barrier.

Goals Investigated the association of DNA repair gene xeroderma pigmentosum group A(XPA) and C(XPC) polymorphisms with the risk of gastric cardiac adenocarcinoma (GCA) in a high incidence region in north China. Background Polymorphisms of a number of DNA repair genes may contribute to variations in DNA repair capacity and genetic susceptibility to different cancers. Study Two single nucleotide polymorphisms of XPA and 3 single nucleotide polymorphisms of XPC were genotyped in 253 GCA patients and 612 healthy controls. Results Family history of upper gastrointestinal cancer may increase the risk of developing GCA. Compared with A/A genotype, A/G+G/G genotype of XPA A23G significantly decreased the risk of developing GCA especially in nonsmoker group. The genotype and allelotype distributions of XPC intron 9 PAT+/− and exon 15 Lys939Gln in GCA patients were not significantly different from that in healthy controls (P>0.05). T allelotype frequencies of XPC exon 8 Val499Ala in GCA patients was significantly lower than that in healthy controls (P<0.05). The C/T genotype frequency of XPC exon 8 in GCA patients (35.6%) was significantly different from that in healthy controls (46.1%) (P=0.01). Compared with individuals with C/C genotype, individuals with T allele (C/T or T/T genotype) had significantly lower risk in developing GCA. We also found that polymorphisms of this 3 XPC locus were in linkage disequilibrium. Conclusions XPA A23G and XPC exon 8 Val499Ala polymorphisms may be useful markers for identifying individuals at risk of developing GCA in the high incidence region of north China.

目的分析河北省食管癌高发区磁县、涉县29年(1974~2002年)上消化道恶性肿瘤的死亡情况,为肿瘤防治提供依据。方法对比分析磁县、涉县同时期20世纪70年代(1974~1976年)、90年代(1990~1992年)、21世纪初(2000~2002年)全人群肿瘤登记的食管癌、贲门癌、非贲门胃癌的死亡率。结果自20世纪70年代到21世纪初,磁县、涉县食管癌粗死率均呈现明显下降趋势,磁县食管癌粗死率下降了40.96/10万,下降了32.21%;而同时期涉县下降了65.74/10万,下降了50.06%。磁县贲门癌和非贲门胃癌的粗死率呈现曲线波动,变化不大,20世纪70年代贲门癌死亡占上消化道恶性肿瘤死亡的5.67%,到90年代占4.58%,21世纪初占8.15%。而涉县贲门癌呈现明显上升趋势,非贲门胃癌呈现明显下降趋势,发现贲门癌在上消化道恶性肿瘤死亡中所占比重越来越大,由20世纪70年代的6.28%上升到新世纪的30.17%。磁县、涉县人群中男性贲门癌的死亡率高于女性。磁县山区贲门癌死亡率高于丘陵和平原,年平均死亡率达到11.61/10万,且有上升趋势。结论29年来磁县、涉县食管癌死亡呈显著下降趋势,磁县贲门癌、非贲门胃癌死亡均呈曲线波动;涉县贲门癌死亡率呈明显上升趋势,非贲门胃癌死亡率呈下降趋势。

Objective To investigate the correlation of XPC intron 9 PAT+/- and exon 15 A2920C SNPs with susceptibility to esophageal squamous cell carcinoma (ESCC) and gastric cardiac adenocarcinoma (GCA) in a population of high incidence region of Hebei Province. Methods XPC intron 9 PAT+/- and exon 15 A2920C SNPs were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis in 327 ESCC patients, 253 GCA patients and 612 healthy controls. Results The overall genotype and allelotype distributions of XPC intron 9 PAT+/- and exon 15 A2920C in ESCC and GCA patients were not significantly different from that in healthy controls(P0.05). When stratified for smoking status and UGIC family history, compared with A/A genotype, C/C genotype significantly increased the risk of developing ESCC in non-smoker group [age and gender and UGIC family history adjusted odds ratio (OR)=2.09, 95%CI=1.14～3.81]. Conclusion C/C genotype of XPC exon 15 may be one of the factors that affect the risk of developing ESCC in non-smoking population in the high incidence region of Hebei Province.

Objective To investigate the association of two polymorphisms of XPA with the risk of susceptibility to esophageal squamous cell carcinoma (ESCC) and gastric cardiac adenocarcinoma (GCA) in a population of high incidence region of Hebei Province. Methods Two polymorphisms of XPA (A23G, at position-4 from the ATG start condon and G709A, at codon 228, in exon 6) were genotyped by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis in 327 ESCC patients, 253 GCA patients and 612 healthy controls. Results The overall genotype and allelotype distributions of XPA A23G in ESCC patients were significantly different from that in healthy controls(P 0.05 ). The A/G+G/G genotype significantly decreased the risk of developing ESCC compared with A/A genotype. Stratified analysis showed that the protective effect was more evident in non-smokers and smokers.The protective effect was more evident in subjects with negative history of UGIC. The overall genotype and allelotype distributions of XPA A23G in GCA patients were not significantly different from that in healthy controls(P 0.05 ). Compared with A/A genotype, A/G+G/G genotype significantly decreased the risk of GCA.When stratified for status, the genotype distributions of XPA A23G in GCA patients were significantly different from that in healthy controls(P 0.05 ). Compared with A/A genotype, A/G+ G/G genotype significantly decreased the risk of GCA in non-smoker group. Conclusion XPA23A/G+G/G genotype may be one of the factors that affect the risk of developing ESCC and GCA in population in the high incidence region of Hebei Province.

Esophageal cancer is one of high mortality tumors in China.The secondary prevention,which put emphasis on the massive screening,early detection and early treatment,would decrease the cancer mortality as well as cancer incidences in relatively short time.That is to prevent esophageal cancer we try to interdict the condition and the course of esophageal cancer.The article will review that secondary prevention in the prevention and treatment of esophageal cancer.