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BACKGROUND: There are obvious advantages to increasing donor retention. However, for reasons of blood safety, certain donors may, in fact, be more desirable to retain than others. “Safe” donors are defined as those who provided a blood donation that was negative on all laboratory screening tests and who subsequently reported no behavioral risks in response to an anonymous survey. This study identifies the most important factors affecting the intention of “safe” donors to provide another donation. STUDY DESIGN AND METHODS: An anonymous survey asking about donation history, sexual history, injecting drug use, and recent donation experience was mailed to 50,162 randomly selected allogeneic donors (including directed donors) who gave blood from April through July or from October through December 1993 at one of the five United States blood centers participating in the Retrovirus Epidemiology Donor Study. Before mailing, questionnaires were coded to designate donors with nonreactive laboratory screening tests at their most recent donation. RESULTS: A total of 34,726 donors (69%) responded, with substantially higher response among repeat donors. According to reported intentions only, the vast majority of “safe” donors indicated a high likelihood of donating again within the next 12 months. Only 3.4 percent reported a low likelihood of donating again. A comparison of those likely to return and those unlikely to return reveals significant differences in demographics and in ratings of the donation experience. A higher proportion of those unlikely to return were first-time donors, minority-group donors, and donors with less education. The highest projected loss among “safe” donors was seen for those who gave a fair to poor assessment of their treatment by blood center staff or of their physical well-being during or after donating. CONCLUSION: These data suggest that efforts to improve donors' perceptions of their donation experience, as well as attention to the physical effects of blood donation, may aid in the retention of both repeat and first-time donors.  相似文献   
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Mathematical genetic analyses were performed on a sample of schizophrenic families (25 probands and 58 first-degree relatives). Heritability coefficients were estimated for EEG power spectrum parameters and their topography, and also for psychological test data on thought and speech process disorder, designed to assess altered selectivity in cognitive activity. Multiple regression equations for genetic counseling regarding the prognosis of mental illness were derived from the neurophysiological and psychological measures.  相似文献   
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The tumour suppressor gene PTEN , which maps to 10q23.3 and encodes a 403 amino acid dual specificity phosphatase (protein tyrosine phosphatase; PTPase), was shown recently to play a broad role in human malignancy. Somatic PTEN deletions and mutations were observed in sporadic breast, brain, prostate and kidney cancer cell lines and in several primary tumours such as endometrial carcinomas, malignant melanoma and thyroid tumours. In addition, PTEN was identified as the susceptibility gene for two hamartoma syndromes: Cowden disease (CD; MIM 158350) and Bannayan-Zonana (BZS) or Ruvalcaba-Riley-Smith syndrome (MIM 153480). Constitutive DNA from 37 CD families and seven BZS families was screened for germline PTEN mutations. PTEN mutations were identified in 30 of 37 (81%) CD families, including missense and nonsense point mutations, deletions, insertions, a deletion/insertion and splice site mutations. These mutations were scattered over the entire length of PTEN , with the exception of the first, fourth and last exons. A 'hot spot' for PTEN mutation in CD was identified in exon 5 that contains the PTPase core motif, with 13 of 30 (43%) CD mutations identified in this exon. Seven of 30 (23%) were within the core motif, the majority (five of seven) of which were missense mutations, possibly pointing to the functional significance of this region. Germline PTEN mutations were identified in four of seven (57%) BZS families studied. Interestingly, none of these mutations was observed in the PTPase core motif. It is also worthy of note that a single nonsense point mutation, R233X, was observed in the germline DNA from two unrelated CD families and one BZS family. Genotype-phenotype studies were not performed on this small group of BZS families. However, genotype-phenotype analysis inthe group of CD families revealed two possible associations worthy of follow-up in independent analyses. The first was an association noted in the group of CD families with breast disease. A correlation was observed between the presence/absence of a PTEN mutation and the type of breast involvement (unaffected versus benign versus malignant). Specifically and more directly, an association was also observed between the presence of a PTEN mutation and malignant breast disease. Secondly, there appeared to be an interdependent association between mutations upstream and within the PTPase core motif, the core motif containing the majority of missense mutations, and the involvement of all major organ systems (central nervous system, thyroid, breast, skin and gastrointestinal tract). However, these observations would need to be confirmed by studying a larger number of CD families.   相似文献   
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The pharmacological kindling with corazol was used as a model of chronic cerebral epileptization. In contrast to sham-operated rats or rats with unilateral occlusion of the common carotid arteries, bilateral occlusion of these vessels moderated acute seizures provoked by a single administration of the convulsant corazol and abated the enhanced cerebral seizure readiness induced by its repeated administration. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 7, pp. 30–33, July, 1998  相似文献   
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BACKGROUND: The Chernobyl accident caused an unprecedented increase in papillary thyroid carcinoma (PTC) incidence with a surprisingly short latency and unusual morphology. We have investigated whether unexpected features of the PTC incidence after Chernobyl were radiation specific or influenced by iodine deficiency. METHODS: PTCs from children from Belarus, Ukraine, and the Russian Federation exposed to fallout from Chernobyl were compared with PTCs from children not exposed to radiation from the same countries, from England and Wales (E&W) and from Japan. The degree and type of differentiation, fibrosis, and invasion were quantified. RESULTS: There were no significant differences between PTCs from radiation-exposed children from Belarus, Ukraine, and the Russian Federation and PTCs from children from the same countries who were not exposed to radiation. Childhood PTCs from Japan were much more highly differentiated (p < 0.001), showed more papillary differentiation (p < 0.001) and were less invasive (p < 0.01) than "Chernobyl" tumors, while tumors from E&W generally showed intermediate levels of degree and type of differentiation and invasion. There was a marked difference between the sex ratios of children with PTCs who were radiation exposed and those who were not exposed (F:M exposed vs. unexposed 1.5:1 vs. 4.2:1; chi(2) = 7.90, p < or = 0.01005). CONCLUSIONS: The aggressiveness and morphological features of Chernobyl childhood PTCs are not associated with radiation exposure. The differences found between tumors from the Chernobyl area, E&W, and Japan could be influenced by many factors. We speculate that dietary iodine levels may have wide implications in radiation-induced thyroid carcinogenesis, and that iodine deficiency could increase incidence, reduce latency, and influence tumor morphology and aggressiveness.  相似文献   
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