Desertification control has been facing severe situations in the interlocking area between cultivated land and grazing land in North China since the Qing Dynasty because of unreasonable land utilization. The paper ana...Desertification control has been facing severe situations in the interlocking area between cultivated land and grazing land in North China since the Qing Dynasty because of unreasonable land utilization. The paper analyzes the policies of all the previous governments to open up land, and examines the historical and geographical background and process by means of historical records. We consider that causes of the area of land desertification to extend are increase of farming migrants, the change of life style of Mongol and weather and land conditions. In order to control the spread of land desertification, we suggest the level of the government to make policies should be improved, the number of farming migrants should be controlled, the Government′s general and specific polices should be actively publicized, and investment in agriculture should be increased.展开更多
The world of Ingmar Bergman is notoriously dark. He exposes us repeatedly to the isolation of human subjectivity and to our desperate attempts to break free of it. To be human for Bergman is to be imperiled, to move i...The world of Ingmar Bergman is notoriously dark. He exposes us repeatedly to the isolation of human subjectivity and to our desperate attempts to break free of it. To be human for Bergman is to be imperiled, to move in an atmosphere of relentless anxiety, and to be driven by passions whose source and power we can neither master nor understand. Is there a period of innocence, a time before we are caught in the coils of the human condition？ The author will argue that Bergman＇s treatment of children demonstrates that in his world birth is the fall from grace.展开更多
Malignant tumors are caused by multiple carcinogenic factors undergoing several stages. The occurrence and development of tumors may be prevented and blocked if some effective interference factors are brought into pla...Malignant tumors are caused by multiple carcinogenic factors undergoing several stages. The occurrence and development of tumors may be prevented and blocked if some effective interference factors are brought into play.1 At present, there are two main subjects for the researches, that is, blocking the precancerous lesions and blocking the develop-ment of tumors. The former focuses on the removing of carcinogenic factors and on the chemoprophylaxis of cancer, while the latter on the inhibition of cancer cell infiltration and cancerometastasis. These are summarized as follows.展开更多
Relationship between the radiation conditions at infinity and the transmitting boundary for numerical simulation of the near-field wave motion has been studied in this paper. The conclusion is that the transmitting bo...Relationship between the radiation conditions at infinity and the transmitting boundary for numerical simulation of the near-field wave motion has been studied in this paper. The conclusion is that the transmitting boundary is approximately equivalent to the radiation conditions at infinity for a large class of infinite media. And the errors of the approximation are of the same order of magnitude as those of the finite elements or finite differences in numerical simulation of wave motion. This result provides a sound theoretical basis for the transmitting boundary used in the numerical simulation of the near-field wave motion and gives a complete explanation for the major experiences accumulated in applications of the transmitting boundary to the numerical simulation.展开更多
基金Supported by the National Natural Science Foundation of China ( No.49831080 ).
文摘Desertification control has been facing severe situations in the interlocking area between cultivated land and grazing land in North China since the Qing Dynasty because of unreasonable land utilization. The paper analyzes the policies of all the previous governments to open up land, and examines the historical and geographical background and process by means of historical records. We consider that causes of the area of land desertification to extend are increase of farming migrants, the change of life style of Mongol and weather and land conditions. In order to control the spread of land desertification, we suggest the level of the government to make policies should be improved, the number of farming migrants should be controlled, the Government′s general and specific polices should be actively publicized, and investment in agriculture should be increased.
文摘The world of Ingmar Bergman is notoriously dark. He exposes us repeatedly to the isolation of human subjectivity and to our desperate attempts to break free of it. To be human for Bergman is to be imperiled, to move in an atmosphere of relentless anxiety, and to be driven by passions whose source and power we can neither master nor understand. Is there a period of innocence, a time before we are caught in the coils of the human condition？ The author will argue that Bergman＇s treatment of children demonstrates that in his world birth is the fall from grace.
文摘Malignant tumors are caused by multiple carcinogenic factors undergoing several stages. The occurrence and development of tumors may be prevented and blocked if some effective interference factors are brought into play.1 At present, there are two main subjects for the researches, that is, blocking the precancerous lesions and blocking the develop-ment of tumors. The former focuses on the removing of carcinogenic factors and on the chemoprophylaxis of cancer, while the latter on the inhibition of cancer cell infiltration and cancerometastasis. These are summarized as follows.
基金the Joint Seismological Science Foundation. Prof. Dai Yishan in Harbin Engineering University has read the manuscript and made relevant comments The expansions of 1/r and r using the Legendre polynomials and the proof of eq (29) on the properties of
文摘Relationship between the radiation conditions at infinity and the transmitting boundary for numerical simulation of the near-field wave motion has been studied in this paper. The conclusion is that the transmitting boundary is approximately equivalent to the radiation conditions at infinity for a large class of infinite media. And the errors of the approximation are of the same order of magnitude as those of the finite elements or finite differences in numerical simulation of wave motion. This result provides a sound theoretical basis for the transmitting boundary used in the numerical simulation of the near-field wave motion and gives a complete explanation for the major experiences accumulated in applications of the transmitting boundary to the numerical simulation.
