首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   296篇
  免费   14篇
  国内免费   6篇
儿科学   14篇
妇产科学   6篇
基础医学   36篇
口腔科学   6篇
临床医学   20篇
内科学   107篇
皮肤病学   7篇
神经病学   8篇
特种医学   38篇
外科学   20篇
综合类   3篇
预防医学   18篇
眼科学   1篇
药学   8篇
肿瘤学   24篇
  2019年   3篇
  2018年   2篇
  2017年   4篇
  2016年   4篇
  2015年   4篇
  2014年   8篇
  2013年   11篇
  2012年   1篇
  2011年   3篇
  2010年   10篇
  2009年   4篇
  2008年   12篇
  2007年   8篇
  2006年   9篇
  2005年   20篇
  2004年   2篇
  2003年   5篇
  2002年   5篇
  2001年   6篇
  2000年   5篇
  1999年   8篇
  1998年   15篇
  1997年   12篇
  1996年   20篇
  1995年   13篇
  1994年   14篇
  1993年   15篇
  1992年   4篇
  1990年   3篇
  1989年   8篇
  1988年   9篇
  1987年   10篇
  1986年   7篇
  1985年   9篇
  1984年   5篇
  1983年   4篇
  1981年   4篇
  1980年   6篇
  1979年   2篇
  1978年   3篇
  1977年   4篇
  1976年   3篇
  1975年   2篇
  1966年   1篇
  1959年   2篇
  1954年   1篇
  1949年   1篇
  1931年   1篇
  1919年   1篇
  1889年   1篇
排序方式: 共有316条查询结果,搜索用时 14 毫秒
81.
A deficiency of protein C (PC), antithrombin, or protein S is strongly associated with deep-vein thrombosis in selected patients and their families. However, the strength of the association with venous thrombosis in the general population is unknown. This study was a population-based, patient-control study of 474 consecutive outpatients, aged less than 70 years, with a first, objectively diagnosed, episode of venous thrombosis and without an underlying malignant disease, and 474 healthy controls who matched for age and sex. Relative risks were estimated as matched odds ratios. Based on a single measurement, there were 22 (4.6%) patients with a PC deficiency (PC activity, less than 0.67 U/mL or PC antigen, less than 0.33 U/mL when using coumarins). Among the controls, the frequency was 1.5% (seven subjects). Thus, there is a threefold increase in risk of thrombosis in subjects with PC levels below 0.67 or 0.33 U/mL [matched odds ratio, 3.1; 95% confidence interval (CI), 1.4 to 7.0]. When a PC deficiency was based on two repeated measurements, the relative risk for thrombosis increased to 3.8 (95% CI, 1.3 to 10); when it was based on DNA-confirmation, the relative risk increased further to 6.5 (95% CI, 1.8 to 24). In addition, there was a gradient in thrombosis risk, according to PC levels. The results for antithrombin are similar to those for PC, although less pronounced (relative risk, 2.2; 95% CI, 1.0 to 4.7). We could not find an association between reduced total protein S (relative risk, 0.7; 95% CI, 0.3 to 1.8) or free protein S levels (relative risk, 1.6; 95% CI, 0.6 to 4.0) and thrombosis risk. Although not very frequent, PC and antithrombin deficiency are clearly associated with an increase in thrombosis risk.  相似文献   
82.
83.
The transfusion of blood may suppress the immune responses of patients with renal transplants and with malignant disorders. To study the in vitro suppressive effects of banked blood, 4 units of blood were stored in CPDA-1 and ADSOL at 4 degrees C for 14 days. Lymphocytes and plasma or ADSOL supernatants were harvested on Days 0, 4, 7, 10, and 14. Subpopulations of lymphocytes were enumerated by flow cytometry. Recalcified and heat-treated plasma and supernatants from the units of blood were added to mixed lymphocyte cultures (MLC) composed of cells from normal individuals. No significant changes were noted in the proportions of T or B cells from blood stored under these conditions. A 60 +/− 3 percent inhibition in the proliferative response was observed when plasma from CPDA-1 units was added to MLCs (p less than 0.02). Supernatants from ADSOL units demonstrated a 29 +/− 4 percent inhibition (p less than 0.10) of the proliferative response, and this inhibition of response was observed on all 14 days of the study. When appropriate concentrations of dextrose or adenine were added to other MLCs, adenine (at the concentration found in ADSOL) caused a significant inhibition of the proliferative response. This inhibition was not, however, as marked as that observed with recalcified, heat- treated plasma from CPDA-1 units. We conclude that adenine plus some additional factor(s) found in the liquid portion of stored blood inhibits the proliferative response of normal lymphocytes. It is possible that these factors contribute to the immune suppression observed in vivo in some patients who receive blood transfusions.  相似文献   
84.
Human herpesvirus 6 activity (HHV-6) was studied in 15 allogeneic and 11 autologous marrow transplantation patients. After transplantation, HHV-6 was isolated from the peripheral blood mononuclear cells of 12 of 26 patients (6 allogeneic and 6 autologous). All isolates were variant B. Eleven of 26 and 12 of 19 patients showed salivary shedding of HHV-6 DNA before and after transplantation, respectively. The antibody titer increased in 7 of 26 patients. Thus, 23 of 26 patients showed evidence of active HHV-6 infection either by virus isolation, salivary shedding, or increases in antibody titers. The fraction of saliva specimens positive in 19 patients was negatively associated with their antibody titers (P= .005). The proportion of cultures positive increased after transplantation (P = .007). Sinusitis was associated with HHV-6 isolation in autologous recipients (P= .002). In allogeneic patients, active human cytomegalovirus infection was associated with HHV-6 isolation (P = .04). No association was observed between HHV-6 infection and GVHD, pneumonia, delay in engraftment, or marrow suppression. Of the 120 clinical events analyzed in 26 patients, HHV-6 was defined as a probable cause of 16 events in 9 patients based on the propinquity of HHV-6 activity and the clinical event plus the absence of other identified causes of the event.  相似文献   
85.
P16 is overexpressed in cutaneous carcinomas located on sun-exposed areas   总被引:1,自引:0,他引:1  
BACKGROUND: Recently, an increased expression of P16, a cell cycle regulatory tumor suppressor protein, has been demonstrated in cervical squamous neoplasms as a marker of malignancy. In contrast, studies performed in skin carcinomas led to contradictory results. OBJECTIVES: Our first aim was to evaluate P16 expression in different types of non-melanoma skin cancers compared with normal skin and benign tumors. The second aim was to evaluate the relationship between P16 expression and the location of skin tumors (i.e. exposed versus non exposed sites). Finally, we also studied Ki67 expression in skin carcinomas and control biopsies. METHODS: Skin biopsy specimens with typical histologic features of squamous cell carcinoma (SCC; n = 30), Bowen's disease (BD; n = 17), basal cell carcinoma (BCC; n = 10), seborrheic keratosis (SK; n = 10) and normal human skin (NHS; n = 9) were obtained from 76 patients seen at our institution between 2001 and 2003. In all cases, P16 and Ki67 expression were evaluated by immunohistochemistry and image analysis. RESULTS: P16 overexpression was observed in 58% of cutaneous carcinomas (SCC: 60%; BD: 58%; BCC: 50%) versus 0% of SK or NHS (0%) (p = 0.006). Ki67 expression in over 5% of tumour cells was observed in 69% of cutaneous carcinomas (SCC: 54%; BD: 76%; BCC: 80%) versus 16% in the group including SK (30%) and NHS (0%) (p = 0.04). Overexpression of P16 was associated with a high rate of Ki67 positive tumour cells in 23/57 malignant skin tumors (40%). Both P16 was associated and Ki-67 were negative in 7/57 cases (12%). Sixty-eight percent of tumors located on sun-exposed areas versus 23% of those located on non sun-exposed areas overexpressed P16 (p = 0.02). CONCLUSION: Our study demonstrated that the expression of P16 and Ki67 is associated with skin carcinomas. No difference was observed according to histological types of carcinomas, suggesting that P16 and Ki67 expression did not correlate with the degree of proliferation and malignancy. Within cutaneous carcinoma specimens, P16 overexpression was significantly associated with the location on sun-exposed areas, suggesting a possible induction of P16 overexpression by UV radiation.  相似文献   
86.
Bone marrow transplantation in patients aged 45 years and older   总被引:5,自引:8,他引:5  
Increasing age has been reported to be a poor prognostic factor for survival after bone marrow transplantation. We evaluated causes of death and frequency and type of complications after marrow grafting in 24 syngeneic and 39 allogeneic recipients who were 45 to 68 years old at the time of transplant. Most patients were in an advanced stage of hematologic malignancy. Among patients given syngeneic transplants, actuarial disease-free survival at 7 years is 20%. The major causes of death were relapse of leukemia and idiopathic interstitial pneumonia. Among allogeneic recipients, 9 (23%) are currently alive, and actuarial disease-free survival at 7 years is 11%. Cytomegalovirus pneumonia and septicemia were the most frequent causes of death. Patients over 50 years of age had the poorest survival rate (1/13), but many of these were transplanted in an advanced stage of their disease. However, among 12 patients transplanted while in remission or at an early stage of their disease, 5 are surviving 65 to 1,160 days after transplantation, with an actuarial survival rate of 22% at 3 years. This is in contrast to those who received their transplant in relapse: 2 out of 20 patients (10%) became long-term survivors, with a probability of survival of 15% at 3 years. The actuarial incidence of grade II through IV acute graft- v-host disease (GVHD) was 30% for allogeneic recipients 45 to 50 years of age. This was not significantly different from the incidence in younger patients. In patients 51 to 62 years of age, the actuarial incidence of acute GVHD was 79%; however, this group included three partially HLA-mismatched transplants. Ten of 15 patients surviving at least 3 months developed chronic GVHD. These results suggest that marrow transplantation is feasible and should be considered in patients over 45 years, especially if recipients are in good clinical condition and are at an early stage of their disease, such as the chronic phase of chronic myelogenous leukemia and preleukemia. For patients more than 50 years of age, allogeneic marrow grafting cannot presently be considered first-line therapy.  相似文献   
87.
88.
We studied the molecular basis and genetic heterogeneity of hereditary antithrombin (III) deficiency in nine Dutch families. Polymerase chain reaction (PCR) amplification and direct sequencing of all antithrombin gene exons and flanking intronic regions identified mutations in eight families. Given the opportunity to correlate the molecular basis with survival, we addressed the relevance of molecular defects to mortality in inherited antithrombin deficiency. The defects included single nucleotide deletions (7671 del G, 7768-69 del G) and insertions (5501 ins A, 2463 G-->TC) that lead to frameshifts, a single base substitution [5381 C-->T (129Arg-->stop)] leading to a premature termination codon, and single base substitutions resulting in amino acid substitutions [2652 A-->C (63Tyr-->Ser), 13380 T-->C (421Ile-- >Thr), and 13407 G-->T (430Cys-->Phe)]. All affected individuals were heterozygous for the defects. Previously we found in Dutch families that antithrombin deficiency did not lead to higher mortality compared with the general population. In accordance with these findings, we observed no excess mortality in the nine families [Observed:Expected, 52:52.6; standardised mortality ratio (SMR) 1.0, 95% confidence interval (CI), 0.7-1.3]. Our findings confirmed a considerable genetic heterogeneity underlying antithrombin deficiency. We therefore concluded that the lack of excess mortality in these families is not caused by a Dutch mild defect. We suggest that the longevity is not affected by molecular defects in the antithrombin gene and hypothesize that differences in mortality or natural history between families most likely result from other (genetic) risk factors.  相似文献   
89.
Between September 1987 and December 1994, 80 patients with multiple myeloma (MM) received high-dose busulfan and cyclophosphamide without (n = 57) or with modified total body irradiation (n = 23) followed by marrow from allogeneic donors. At transplant, 71% of the patients had disease that was refractory to chemotherapy. Thirty-five patients died of transplant-related causes within 100 days and 11 deaths occurred later. The actuarial probabilities of survival and progression-free survival were .24 +/- 0.17 and .20 +/- 0.10 at 4.5 years. Complete remissions were obtained in 36% of patients who had actuarial probabilities of survival and event-free survival of .50 +/- 0.21 and .43 +/- 0.17 at 4.5 years. In a multivariate analysis, adverse risk factors for outcome endpoints included: transplantation greater than 1 year from diagnosis; beta-2 microglobulin > 2.5 at transplant; female patients transplanted from male donors; patients who had received greater than eight cycles of chemotherapy before transplant and Durie stage 3 disease at the time of transplant. These results indicate that allografting for patients with MM can result in long-term disease-free survival for a minority of patients. Efforts to reduce transplant- related mortality should focus on earlier transplantation, less toxic treatment regimens, better supportive care, and improved prevention and treatment of graft-versus-host disease (GVHD).  相似文献   
90.
Treatment of preleukemic syndromes with marrow transplantation   总被引:2,自引:0,他引:2  
Thirty patients with advanced preleukemic syndromes were treated with marrow transplantation. Most cases were diagnosed by the presence of peripheral pancytopenia and a diagnostic marrow examination but in 6 of the 30 patients pretransplant chromosome studies were instrumental in establishing the diagnosis. Three patients prepared for transplantation with cyclophosphamide alone recurred with their disease within 6 months of transplantation. The other 27 patients were treated with cyclophosphamide and total body irradiation. Twenty of these 27 patients had preleukemia not associated with prior therapy or severe marrow fibrosis. Thirteen of these 20 are alive and well 9 to 56 months from transplant and 7 died, 4 of interstitial pneumonia, 2 of candida septicemia, and 1 of disseminated zoster. There have been no disease recurrences in this group. The remaining preleukemic patients, which include 3 patients transplanted for preleukemia secondary to prior therapy and 4 patients transplanted for preleukemia associated with severe marrow fibrosis, have all died. Major problems in these patients included disease recurrence (2 cases) and, in those with severe marrow fibrosis, graft failure (2 cases). These results suggest that for patients with life-threatening pancytopenia due to spontaneous preleukemia without severe marrow fibrosis, marrow transplantation can prolong disease-free survival and may result in cure of the disease.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号