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   431篇
  免费   34篇
  国内免费   67篇
耳鼻咽喉   2篇
儿科学   43篇
妇产科学   2篇
基础医学   61篇
口腔科学   25篇
临床医学   78篇
内科学   109篇
皮肤病学   2篇
神经病学   9篇
特种医学   96篇
外科学   14篇
综合类   18篇
预防医学   9篇
眼科学   2篇
药学   47篇
中国医学   2篇
肿瘤学   13篇
  2019年   4篇
  2018年   4篇
  2017年   8篇
  2016年   4篇
  2015年   5篇
  2014年   5篇
  2013年   8篇
  2012年   9篇
  2011年   8篇
  2010年   10篇
  2009年   12篇
  2008年   10篇
  2007年   44篇
  2006年   15篇
  2005年   16篇
  2004年   6篇
  2003年   10篇
  2002年   14篇
  2001年   16篇
  2000年   13篇
  1999年   9篇
  1998年   26篇
  1997年   26篇
  1996年   25篇
  1995年   18篇
  1994年   19篇
  1993年   10篇
  1992年   3篇
  1991年   5篇
  1990年   13篇
  1989年   15篇
  1988年   20篇
  1987年   12篇
  1986年   12篇
  1985年   18篇
  1984年   6篇
  1983年   10篇
  1982年   8篇
  1981年   8篇
  1980年   6篇
  1978年   7篇
  1977年   6篇
  1976年   5篇
  1975年   7篇
  1970年   2篇
  1964年   1篇
  1962年   1篇
  1960年   4篇
  1959年   1篇
  1958年   1篇
排序方式: 共有532条查询结果,搜索用时 15 毫秒
51.
52.
AIM: To investigate the signifi cance of ileocolonoscopy with histology in the evaluation of post-transplantation persistent diarrhea (PD). METHODS: We retrospectively reviewed all records of renal transplant patients with PD, over a 3-year period. All patients were referred for ileocolonoscopy with biopsy, following a negative initial diagnostic work up. Clinical and epidemiological data were compared between cases with infectious or drug-induced diarrhea. RESULTS: We identif ied 30 episodes of PD in 23 renaltransplant patients (1-3 cases per patient). There were 16 male patients and the mean age at the time of PD was 51.4 years. The average time from transplantation to a PD episode was 62.3 ± 53.2 mo (range 1-199 mo). Ileocolonoscopy detected mucosal abnormalities in 19 cases, whereas the intestinal mucosa appeared normal in 11 cases. Histological examination achieved a specific diagnosis in 19/30 cases (63.3%). In nine out of 11 cases (82%) with normal endoscopic appearance of the mucosa, histological examination of blinded biopsies provided a specif ic diagnosis. The etiology of PD was infectious in 11 cases (36.6%), drug-related in 10 (33.3%), of other causes in three (10%), and of unknown origin in six cases (20%). Infectious diarrhea occurred in significantly longer intervals from transplantation compared to drug-related PD (85.5 ± 47.6 mo vs 40.5 ± 44.8 mo, P < 0.05). Accordingly, PD due to drug-toxicity was rarely seen after the f irst year post-transplantation. Clinical improvement followed therapeutic intervention in 90% of cases. Modif ication of immunosuppressive regimen was avoided in 57% of patients. CONCLUSION: Early ileocolonoscopy with biopsies from both affected and normal mucosa is an important adjunctive tool for the etiological diagnosis of PD in renal transplant patients.  相似文献   
53.
54.
In order to target the appropriate age population for booster vaccination, we examined the antibody titres against pertussis toxin (PT) in different age groups in immunized and non-immunized individuals. In the immunized population, the highest anti-PT levels were observed in the 0- to 2-y age group and the lowest in the teenager and young adult groups. In contrast, in the control group, anti-PT levels were minimal in infants and young children, increasing in adolescence and early adulthood, and waning after 30 y of age. Antibody levels >30 U/ml were observed with higher frequency in children <2 y of age, in individuals with complete vaccination history and in non-immunized individuals. These findings may have important implications in optimizing vaccination policies.  相似文献   
55.
小鼠颅神经嵴细胞的培养和特征   总被引:6,自引:4,他引:2  
目的:在体外原代培养Balb/c小鼠胚胎的颅神经嵴细胞。为颅面部各种组织细胞的发育研究提供细胞来源。方法:采用胰酶消化法分离小鼠胚胎第8.5天的颅神经管,从小鼠颅神经管中游离出来的细胞即为颅神经嵴细胞,用免疫组织化学方法鉴定细胞的来源,并测定细胞的生长曲线。结果:成功地培养出小鼠的颅神经嵴细胞,其形态类似成纤维样细胞,免疫组化检测结果表明,神经特异性烯醇化酶(NSE)抗体染色结果阳性。细胞的群体倍增时间为43.65h。结论:原代培养的小鼠颅神经嵴细胞生长稳定,来源明确,是颅面部各种细胞的发育和分化研究中一种有用的工具。  相似文献   
56.
Group A streptococcus (GAS) is an important cause of morbidity and mortality worldwide. Surveillance of emm types has important implications, as it can provide baseline information for possible implementation of vaccination. A total of 1,349 GAS pediatric isolates were collected during a 7-year period (2007 to 2013); emm typing was completed for 1,282 pharyngeal (84%) or nonpharyngeal (16%) isolates, and emm clusters and temporal changes were analyzed. Thirty-five different emm types, including 14 subtypes, were identified. The most prevalent emm types identified were 1 (16.7%), 12 (13.6%), 77 (10.9%), 4 (10.8%), 28 (10.4%), 6 (6.8%), 3 (6.6%), and 89 (6.6%), accounting for 82.3% of total isolates. Rheumatogenic emm types comprised 16.3% of total isolates. The emm types 12, 4, and 77 were more prevalent among pharyngeal isolates, and the emm types 1, 89, 6, 75, and 11 were more prevalent among nonpharyngeal isolates. The emm types identified belonged to 13 emm clusters, and the 8 most prevalent clusters comprised 97% of all isolates. There were statistically significant decreases in the prevalence of emm types 12, 4, 5, and 61 and increases in the prevalence of emm types 89, 75, and 11, compared with the period 2001 to 2006. The proposed 30-valent GAS vaccine, which is currently in preclinical studies, encompasses 97.2% of the emm types detected in our study and 97.4% of the erythromycin-resistant strains. In addition, it includes 93.3% of the emm types involved in bacteremia. A much greater diversity of GAS emm types was identified in our area than described previously. Seasonal fluctuations and the introduction of new emm types were observed. Continuous surveillance of emm types is needed in order to evaluate the possible benefits of an M protein-based GAS vaccine.  相似文献   
57.
Twenty-six patients with progressive Hodgkin's disease after conventional chemotherapy received intensive chemoradiotherapy and autologous bone marrow transplantation (ABMT); 19 also received additional involved-field radiotherapy. Twenty-one patients [81%, 95% confidence intervals (CI) 61% to 94%] attained complete (n = 18) or partial responses. Ten patients (38%, 95% CI 20% to 59%) are disease- free a median of 4.5 years later (range 3.5 to 7.0 years), including seven patients with continuous complete responses. The likelihood of overall response was not significantly influenced by any clinical or treatment variable examined. However, there was a trend favoring patients with higher Karnofsky scores, and higher scores were associated with attainment of complete responses (P = .06 and P = .02, respectively, Mann-Whitney U test). Both higher Karnofsky scores and shorter durations of disease before transplantation were associated with improved survival in a stepwise Cox multivariate analysis. The chief cause of failure was progression at sites previously involved with Hodgkin's disease. No patient relapsed in the marrow, and two of three patients with a history of marrow involvement with Hodgkin's disease achieved durable complete responses after transplantation. These data suggest that inadequate pretransplant conditioning, and not the reinoculation of occult tumor cells in the autologous marrow, caused most relapses. Fatal treatment-related toxicity occurred in six patients. Three patients died of idiopathic interstitial pneumonitis; each had previously received local mediastinal irradiation before intensive chemoradiotherapy. Intensive chemoradiotherapy and ABMT produces durable responses in some patients with Hodgkin's disease incurable with conventional therapy. Use of such therapies at the first sign of failure with conventional chemotherapy and development of more effective conditioning regimens should further improve results.  相似文献   
58.
During the course of differentiation of early human myeloid cells toward monocytes and granulocytes, cell surface expression of the cell adhesion molecule, CD11b/CD18 (Mo1) increases dramatically and expression of myeloperoxidase (MPO), a bacteriocidal enzyme, decreases markedly. Using the inducible promyelocytic cell line HL-60 as a model, we studied the mRNA expression of these genes. Differentiation of these cells along both a monocytic and a granulocytic pathway demonstrated that the mRNA levels of the two subunits of CD11b/CD18 increased in a pattern temporally and quantitatively similar to the increase in cell surface expression of this heterodimer. In contrast, the expression of MPO mRNA decreased in a temporal and quantitative pattern similar to the known decrease in MPO protein during differentiation, suggesting that regulation of these myeloid-specific proteins may occur at the level of mRNA expression. These findings have important implications with regard to the nature of the block in differentiation in acute nonlymphocytic leukemia and the regulation of myeloid gene expression.  相似文献   
59.
High-dose (HD) cytosine arabinoside (ARA-C) is more effective treatment than conventional-dose ARA-C regimens for patients with relapsed acute nonlymphocytic leukemia (ANLL). We report here that HD ARA-C given during the first remission of ANLL has resulted in long remission durations and a high proportion of patients who survive more than three years free of disease. From August 1979 to September 1983, 36 adult patients with ANLL in first remission received one to three courses of HD ARA-C (3 g/m2 by one-hour infusion every 12 hours for 12 doses on days 1 through 6) alone or with daunorubicin (30 mg/m2 for two or three doses on days 7 through 9). Three patients died of sepsis or hemorrhage during consolidation, and 14 patients have relapsed from five to 48 months after diagnosis. The remaining 19 patients are in continued complete remission (CCR) from 11 to 62 months. Denoting all deaths in remission as relapse, the actuarial probability of CCR is 42% at 62 months, with an apparent plateau in the survival curve. Of the first 22 patients treated, ten remain in CCR from 37 to 62 months with no therapy for at least three years. Due to its heightened anti-leukemic activity, HD ARA-C allows brief but effective consolidation of ANLL in first remission, with long-term disease-free survival comparable to other approaches.  相似文献   
60.
Patients with hairy cell leukemia (HCL) and chronic lymphocytic leukemia (CLL) were treated with recombinant interferon alpha A (rIFN- alpha A). The binding of iodinated recombinant interferon-alpha to baseline samples of peripheral blood mononuclear cells (PBMCs) from the leukemia patients was compared with clinical responsiveness to rIFN- alpha A. HCL patients (8/10) responded to rIFN-alpha A therapy, whereas none (0/10) of the CLL patients studied responded. The PBMCs from the eight responsive HCL patients bound approximately twice as much iodinated interferon as the PBMCs from nonresponsive CLL patients. This difference was due to more high-affinity receptors per cell with no difference in the affinity of the interferon-receptor interaction. However, because PBMCs from HCL patients were larger than PBMCs from CLL patients, the cell surface receptor density was similar. The leukemic cells from one of the two nonresponsive HCL patients bound iodinated interferon similarly to the cells from the responsive HCL patients, whereas the leukemic cells from the other nonresponsive HCL patient bound considerably less. The rapidity of response of the HCL patients did not correlate with the level of binding of iodinated interferon. Our results suggest that the absolute number of interferon receptors per cell may be only one of several important parameters in the response to rIFN-alpha A therapy, and that the responsiveness of a particular lymphoproliferative disease or a particular patient to rIFN- alpha A therapy cannot be predicted or explained solely by the degree of interaction between IFN and its cell surface receptor.  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