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81.
Summary
Background. The histogenesis of pancreatic cancer is still debatable. Ductal, ductular, and acinar cells all have been declared the tumor
progenitor cells. Our long-term human and experimental studies indicate that pancreatic ductal adenocarcinomas arise within
ductal cells and islets. Supporting studies are presented in this article.
Methods. Several human studies and experimental studies on Syrian hamsters conducted within the last 20 years were used in this article.
Hamster and human islets were established, and their growth and morphologic changes were examined electron microscopically,
immunohistochemically, cytogenetically, and molecular biologically.
Results. Studies using the hamster pancreatic cancer model showed that most pancreatic adenocarcinomas develop within islets, most
probably from stem cells, which are also believed to be the progenitor cells for tumors that develop within ducts. Studies
in newly established human and hamster islets culture validated the immense potential of islet cells to differentiate and
become malignant. The higher susceptibility of islet cells to become malignant could be related to their high drug-metabolizing
enzymes and their high proliferation rate. Dietary studies indicate that the promoting effect of a high-fat diet on pancreatic
carcinogenesis is unrelated to the energy intake, but rather is related to its effect on islet cell replication.
Conclusion. Experimental and human studies during 20 years of research in our laboratories point to the importance of pancreatic
islets in the development of ductal-type adenocarcinomas. We believe that pancreatic cancer that develops within ducts, but
more frequently within islets, derives from pancreatic stem cells that are distributed within the ductal trees and within
the islets
The data was presented at the 8th meeting of the International Association of Pancreatology, as the IAP Founder’s Lecture
July 14, 1998 in Tokyo, Japan. 相似文献
82.
83.
Hideaki Takasaki Eiji Uchida Margaret A. Tempero David A. Burnett Richard S. Metzgar Parviz M. Pour 《Journal of gastrointestinal cancer》1987,2(5-6):349-360
Summary Thirty-eight human pancreatic cancer cases were examined by immunohistochemistry for expression of CA 19-9 and DU-PAN-2 antigens
by the respective monoclonal antibodies. CA 19-9 was expressed in 82% and DU-PAN-2 in 87% of cases. A combination of two antibodies
increased the reactivity to 97%. Six CA 19-9-negative cases were DU-PAN-2 positive and 4 DU-PAN-2-negative cases expressed
CA 19-9. In only 1 case (an anaplastic carcinoma), neither of the antibodies was reactive with cancer cells. The reactivity
of tumor cells with each of the antibodies varied from case to case, and, within the same tumor, from one area to another.
Histologically, all but one tumor were adenocarcinomas. Thirty-five cases showed areas of either a moderate degree of differentiation
(16 cases), poor differentiation (11 cases) or anaplastic areas (8 cases). Although both antigens were expressed in a greater
number of cancer cells in well differentiated areas, and less frequently in poorly differentiated and anaplastic regions,
the difference in antigen expression in relation to the degree of tumor differentiation was not statistically significant.
The cellular localization of the antigens varied. DU-PAN-2 was primarily localized within the cytoplasm, whereas CA 19-9 was
found mostly on the luminal cell surface and in luminal content of the glandular structure. In tumor-free pancreatic tissue,
adjacent to the tumor, CA 19-9 was detected almost exclusively in the cells of large and medium sized ducts, whereas DU-PAN-2
was primarily expressed in terminal ductular and centrocinar cells. The results indicate that a cocktail of CA 19-9 and DU-PAN-2
antibodies could increase the likelihood of identifying a biomarker in most patients with pancreatic cancer. 相似文献
84.
85.
Background/purpose: During the recent years, many diagnostic methods have been proposed aiming at early detection of malignant melanoma. The texture of skin lesions is an important feature to differentiate melanoma from other types of lesions, and different techniques have been designed to quantify this feature. In this paper, we discuss a new approach based on independent component analysis (ICA) for extraction of texture features of skin lesions in clinical images.
Methods: After preprocessing and segmentation of the images, features that describe the texture of lesions and show high discriminative characteristics are extracted using ICA, and then these features, along with the color features of the lesions, are used to construct a classification module based on support vector machines for the recognition of malignant melanoma vs. benign nevus.
Results: Experimental results showed that combining melanoma and nevus color features with proposed ICA-based texture features led to a classification accuracy of 88.7%.
Conclusion: ICA can be used as an effective tool for quantifying the texture of lesions. 相似文献
Methods: After preprocessing and segmentation of the images, features that describe the texture of lesions and show high discriminative characteristics are extracted using ICA, and then these features, along with the color features of the lesions, are used to construct a classification module based on support vector machines for the recognition of malignant melanoma vs. benign nevus.
Results: Experimental results showed that combining melanoma and nevus color features with proposed ICA-based texture features led to a classification accuracy of 88.7%.
Conclusion: ICA can be used as an effective tool for quantifying the texture of lesions. 相似文献
86.
The low rate of understanding and the limited domain of attention are two important and distinctive characteristics of mental retardation. One of the important strategies to provide effective education for these subjects is to lessen the backgrounds and impacts of these affective factors. The aim of this research was to find the effect of computer games program on the amount of mentally retarded persons' attention. Sixty educable male mentally retarded subjects were selected from two 24-h care centres in Tehran. The Toulouse-Pieron Scale was used to determinate the subjects' attention at pre-post test. Members of the experimental group were subjected to 35 sets of computer games. After use of the sets of computer games, the attention scores of the subjects were assessed immediately after the intervention and 5 weeks later. The results showed that exactly after the intervention the average attention scores of the experimental group were significantly higher than those of the control group. But, 5 weeks after the intervention, there was actually no significant difference. 相似文献
87.
88.
89.
Febrile seizures are the most common form of childhood seizures. Although the literature associates certain micronutrients with febrile seizures, there is limited information about the effects of such micronutrients. This study aimed to determine the relationship between serum selenium level and simple febrile seizures in children. This case-control study was conducted in the Children's Hospital in Qazvin, Iran, in 2008. The serum selenium level of 30 children who experienced simple febrile seizures (case group) was measured and compared with that of 30 febrile children without seizure (control group). The serum selenium level was measured by flame atomic absorption spectrophotometer. Data were analyzed by using t-test. Mean ± standard deviation of serum selenium level in the case and control groups was 44.4 ± 10.9 and 63 ± 9.78 μg/dL, a significant difference (P < 0.001). In the case group, 18/30 patients (60%) had a serum selenium level below the norm of 46?μg/dL, whereas serum selenium level in the entire control group was within the normal range (P < 0.01). The serum selenium level in the children who had simple febrile seizures was significantly lower than in the nonseizure control group. It seems that there is an association between serum selenium deficiency and simple febrile seizures; however, further study is recommended. 相似文献
90.