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   670篇
  免费   43篇
耳鼻咽喉   7篇
儿科学   9篇
妇产科学   8篇
基础医学   67篇
口腔科学   25篇
临床医学   45篇
内科学   147篇
皮肤病学   9篇
神经病学   61篇
特种医学   13篇
外科学   80篇
综合类   20篇
预防医学   96篇
眼科学   20篇
药学   65篇
中国医学   8篇
肿瘤学   33篇
  2024年   3篇
  2023年   8篇
  2022年   24篇
  2021年   35篇
  2020年   19篇
  2019年   29篇
  2018年   26篇
  2017年   23篇
  2016年   28篇
  2015年   25篇
  2014年   35篇
  2013年   35篇
  2012年   74篇
  2011年   65篇
  2010年   33篇
  2009年   29篇
  2008年   39篇
  2007年   44篇
  2006年   40篇
  2005年   30篇
  2004年   23篇
  2003年   15篇
  2002年   9篇
  2001年   1篇
  2000年   4篇
  1999年   2篇
  1998年   2篇
  1997年   2篇
  1995年   1篇
  1994年   1篇
  1993年   2篇
  1992年   1篇
  1989年   1篇
  1986年   2篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有713条查询结果,搜索用时 10 毫秒
31.
ABSTRACT: BACKGROUND: To compare the predictive ability of adolescent lipoprotein classification using the National Examination Survey (NHANES) cut points and those of the National Cholesterol Education Program (NCEP) for predicting abnormal levels in adulthood. METHOD: From 1032 adolescents, aged 14--19 years, participants of the Tehran Lipid and Glucose Study, all lipid measures were determined at baseline and again after 6 years. Multivariable Odds Ratios (ORs) were calculated for borderline and high categories of lipids to predict dyslipidemia in adulthood, considering the normal level as a reference. Area under the receiving characteristics curve (AUC) was used to assess the predictive ability of each adolescent lipid classification.ResultApplying the NCEP classification, the prevalences of high total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides and low high density lipoprotein cholesterol (HDL-C) in males were 12.1%, 12.9%, 26.1% and 34.2% respectively; in females the corresponding prevalences were 15.4%, 17.9%, 21.4% and 25.0%, respectively. Using NHANES cut points, the prevalence of high TC, LDL-C and triglycerides were lower, than those defined by NCEP; the ORs of high categories of lipids (defined by NHANES) were higher than ORs based on the NECP classification, except for HDL-C. For all lipid measures, both classifications had similar predictive abilities, except for TC/HDL-C, which had higher predictive power applying the NHANES classification rather than the NCEP one (AUC 71% vs. 68%, respectively). CONCLUSION: No differences were found between NCEP and NHANES classifications for prediction of adult dyslipidemia, except for TC/HDL-C. Because of their simple application, NCEP cut points can be used in clinical settings.  相似文献   
32.
Aim: This study was conducted to investigate the effect of oral vitamin E on mucositis and neutropenia in patients with leukemia. Methods: This was a randomized double‐blind placebo controlled clinical trial of 60 patients with leukemia (acute lymphoblastic, acute myelogenous leukemia and chronic myelogenous leukemia) who were consecutive recipients of allogenic bone marrow transplantation (BMT), randomly assigned to receive 400 mg vitamin E twice daily (supplemented group) or placebo (control). The incidence and severity of mucositis and the mean duration of neutropenia were compared. Results: The mean duration of neutropenia and the incidence of the mucositis between the two groups was the same (P = 1.0). The difference between the placebo group and mucositis grade 1 (P = 0.31), grade 2 (P = 0.25), grade 3 (P = 0.93) and grade 4 (P = 0.32) was not statistically significant. Moreover the variables of age, sex, BMI and underlying disease had no effect. Conclusion: In this study supplementation with oral vitamin E had no effect on mucositis and neutropenia in patients with leukemia who were recipients of allogenic BMT. More interventional trials are warranted.  相似文献   
33.
OBJECTIVE: To evaluate the mass treatment of ascariasis in rural areas of Hamadan Province, Islamic Republic of Iran. METHODS: A control programme in rural areas of Hamadan Province, which began in November 1997, involved giving all persons a single dose of 400 mg albendazole at intervals of three months. The efficacy of the treatment was evaluated by the formalin-ether concentration technique for stool examination and by the Stoll quantitative method. FINDINGS: The average rate of infection with Ascaris before treatment was 53.3%, ranging from 40% in Hamadan district to 75% in Toysercan. Two areas, Malayer and Nahavand, were excluded from the programme because the infection rates were only 13% and 4%, respectively. After two years of mass treatment the infection rate had decreased to 6%. The proportion of positive cases excreting only unfertilized eggs increased to 32%. No side-effects of mass treatment were observed. CONCLUSION: Systematic mass treatment giving high coverage proved to be very effective in the control of ascariasis, notwithstanding a lack of other preventive measures.  相似文献   
34.
OBJECTIVES: Recently, New York City and New York State increased cigarette excise taxes and New York City implemented a smoke-free workplace law. To assess the impact of these policies on smoking cessation in New York City, we examined over-the-counter sales of nicotine replacement therapy (NRT) products. METHODS: Pharmacy sales data were collected in real time as part of nontraditional surveillance activities. We used Poisson generalized estimating equations to analyze the effect of smoking-related policies on pharmacy-specific weekly sales of nicotine patches and gum. We assessed effect modification by pharmacy location. RESULTS: We observed increases in NRT product sales during the weeks of the cigarette tax increases and the smoke-free workplace law. Pharmacies in low-income areas generally had larger and more persistent increases in response to tax increases than those in higher-income areas. CONCLUSIONS: Real-time monitoring of existing nontraditional surveillance data, such as pharmacy sales of NRT products, can help assess the effects of public policies on cessation attempts. Cigarette tax increases and smoke-free workplace regulations were associated with increased smoking cessation attempts in New York City, particularly in low-income areas.  相似文献   
35.
The effect of oral anticoagulation on clotting during hemodialysis   总被引:1,自引:0,他引:1  
BACKGROUND: Between 5% and 10% of hemodialysis patients are treated with oral anticoagulants. It is currently unknown whether additional anticoagulation with heparin or low-molecular-weight heparin (LMWH) is needed to prevent clotting during hemodialysis. METHODS: In this prospective, randomized, cross-over study 10 patients treated with oral anticoagulants (phenprocoumon) received either no additional anticoagulation or low dose dalteparin (bolus of 40 IU/kg body weight) before dialysis. Efficacy of hemodialysis was measured by normalized weekly Kt/V and urea reduction rate (URR). Thrombus formation was evaluated by measurement of D-dimer and inspection of air traps and dialyser. RESULTS: The median international normalized ratio (INR) did not differ between both observation periods (phenprocoumon 2.2(2 to 3) vs. dalteparin 2.1(2 to 2.9). The anti-Xa level in dalteparin patients was 0.33 (0.27 to 0.38) IU/mL after 2 hours and 0.16 (0.03 to 0.23) IU/mL after 4 hours of hemodialysis. The median increase of D-dimer was significantly higher in patients without additional dalteparin therapy during hemodialysis (DeltaD-dimer 0.23 microg/mL vs. 0.03 mug/mL) (P= 0.0004). Complete thrombosis of the dialyser membrane occurred in one patient in the phenprocoumon group but in none with combined treatment. The extent of thrombosis in the arterial and venous air trap and dialyser was significantly less in patients with additional dalteparin therapy (P= 0.0014, P= 0.0002, and P= 0.0005, respectively). Weekly Kt/V and URR was similar in both groups. CONCLUSION: Standard oral anticoagulation with an INR between 2 and 3 is insufficient to prevent clotting during hemodialysis. Additional low dose anticoagulation with a LMWH or heparin is necessary to facilitate treatment.  相似文献   
36.
In April 1947, during a smallpox outbreak in New York City (NYC), more than 6 million people were vaccinated. To determine whether vaccination increased cardiac death, we reviewed NYC death certificates for comparable periods in 1946, 1947, and 1948 (N = 81,529) and calculated adjusted relative death rates for the postvaccination period. No increases in cardiac deaths were observed.  相似文献   
37.
The routine availability of murine models of various cerebral circulatory disorders requires characterization of the regulation of cerebral artery tone in the mouse. Using vasoconstrictors and vasodilators with known efficacy in the cranial circulation of other species, we determined the pharmacological properties of the isolated pressurized mouse middle cerebral artery (MCA). The maximal pressure-induced myogenic constriction in isolated mouse MCA was 20.6+/-2.4%. Inhibition of nitric oxide (NO) and endothelin-1 (ET-1) altered the extent of pressure-induced myogenic tone. Isolated mouse MCA failed to either constrict or relax to 5-hydroxytryptamine (5-HT) and histamine; other vasoconstrictors demonstrated the following rank order of efficacy: ET-1>phenylephrine>U-46619. The rank order of endothelium-dependent vasodilator efficacy was bradykinin (BK)>acetylcholine (ACh)>substance P. The constriction produced by phenylephrine (PE) required a smaller increase in intracellular Ca(2+) elevation compared to constriction of a similar magnitude produced by membrane depolarization with potassium chloride (KCl). Pressure-induced myogenic tone (20-80 mm Hg) in mouse MCA was associated with smooth muscle cell membrane depolarization (-52.6+/-0.9 to -37.3+/-1.75 mV). Pressure-induced myogenic tone occurred with a smaller change in membrane potential compared to tone of a similar magnitude produced with KCl (-43.37+/-2.66 vs. -29.47+/-1.05 mV). The mouse MCA has a pharmacological profile that is distinct from other species including humans; however, similar to findings in other cerebral arteries, the mouse MCA shows intracellular sensitization to Ca(2+) following receptor activation.  相似文献   
38.
Anti-CD20 antibodies radiolabeled with I-131 tositumomab (Bexxar) or Y-90-Ibritumomab tiuxetan (Zevalin), are similarly efficacious in treating chemotherapy-refractory non-Hodgkin's lymphoma. The relative merits of both radioimmunoconjugates with respect to practical issues, including radiation exposure risk, the advantages and disadvantages of the respective isotopes and other parameters that could affect a patient's quality of life are also important. I-131-labeled antibody treatment often requires inpatient hospitalization due to the inherent risk of exposure from gamma emissions, and patients and families should follow detailed instructions to prevent undue exposure. Other issues relevant to patients and medical staff include: (1) the need for dosimetry to calculate effective therapeutic doses of I-131-labeled anti-B1 (Bexxar) compared with the lack of correlation of dosimetry with marrow toxicity for IDEC-Y2B8 (Zevalin), (2) determining the acute and long-term toxic effects of each agent, (3) time commitments for nuclear medicine staff and patients along with the relative ease of administration, and (4) cost considerations. A more challenging future issue will be to determine the optimal use of Bexxar and Zevalin alone and in combination in ways that will significantly affect patient outcome without compromising quality of life. The recent demonstration of significant response rates in patients having chemotherapy-refractory Non-Hodgkin's Lymphoma (NHL) using both on I-131- and Y-90-labeled anti-CD20 antibodies with minimal toxicity has stimulated comparison of I-131 tositumomab (Bexxar) and Ibritumomab tiuxetan (Zevalin) in terms of radiation safety requirements, the advantages and disadvantages of both radionuclides, and quality-of-life (QOL) issues. Therefore, in this review, we attempt to compare the relative merits of (Bexxar and Zevalin) and address important practical considerations that may influence patient and physician choices regarding treatment using these agents.  相似文献   
39.
The purpose of the present study was twofold: (1) to investigate how many diabetic patients and types of cases that are treated with dental implants in our clinic; and (2) assess the outcome of such treatment. Medical records from 782 patients were examined in patients treated by the Br?nemark method for partial or total edentulism with implant supported bridges. From these records, 25 patients (3.2%) with diabetes before implant treatment (136 implants) were identified and further studied with respect to age, gender, type of diabetes, treated jaw, degree of edentulism, bone graft, implant survival, periimplant inflammation, bleeding on probing, and radiographic bone loss. Furthermore, the patients' opinion about the outcome of the treatment was registered. The implant success rate was 96.3% during the healing period and 94.1% 1 year after surgery. Of all 38 bridges, one was lost. Few complications occurred and all patients, except for one, were satisfied with the treatment. Today, diabetic patients are being treated successfully for all types of edentulism, including bone-grafting treatment. Diabetics that undergo dental implant treatment do not encounter a higher failure rate than the normal population, if the diabetics' plasma glucose level is normal or close to normal as assessed by personal interviews.  相似文献   
40.
BACKGROUND: Control of hyperlipidemia is vital in patients with cardiovascular disease (CVD). Omega-3 fatty acids (n-3FAs) have desirable effects on serum triglyceride (TG) levels, thrombosis, and arrhythmia, but lead to increases in serum low-density lipoprotein (LDL) and apo-B as well. OBJECTIVE: To determine and compare the effects of administration of n-3FAs, vitamin C (VitC) and n-3FAs + VitC on the serum levels of LDL, apoB, other serum lipids, and malondialdehyde (MDA). The present study was performed in Tehran University of Medical Sciences from 2000 to 2001. DESIGN: In a double-blind, placebo trial of parallel design, 68 hyperlipidemic patients [total cholesterol (TC) and TG greater than 200 mg/dL] were randomly assigned to receive daily 500 mg VitC, 1 g n-3FAs, 500 mg VitC + 1 g n-3FAs, or placebo (control) for 10 weeks. Fasting blood samples were collected at the beginning and at the end of the period. TG, TC, LDL-cholesterol-C (LDL-C), and high-density lipoprotein-cholesterol (HDL-C) were measured enzymatically, VitC and MDA colorimetrically, and apo-B and apo-A-I immunoturbidometrically. The pattern of food consumption, socio-economic, and anthropometric indices were determined; there was no significant change in these indices during the study. RESULTS: There was a significant difference in the blood VitC level at the end of the study in comparison to the initial value in the VitC (p = 0.001) and VitC + n-3FAs (p = 0.027) groups. Similarly, the serum TG level at the end of study was significantly different from the initial value in the n-3FAs group (p = 0.002) and also from the final value in the control group (p = 0.013). In the VitC group, there was a significant decrease in TC (p = 0.004), apo-B (p = 0.005), and MDA (p = 0.015) at the end of study as compared to the respective initial values. There was also a significant increase in blood VitC compared to the control value (p = 0.018) and a significant decrease in MDA compared to the n-3FAs group (p = 0.034). At the end of study, in the n-3FAs group, there was a significant (p = 0.04) and a marginally significant decrease (p = 0.05), respectively, in TG/HDL and apo-B levels as compared to the initial values, and the TG/HDL ratio showed a significant decrease as compared to the control group (p = 0.047). CONCLUSION: Simultaneous administration of n-3FAs and VitC had no beneficial effects on the lipid profile of hyperlipidemic patients, but 1 g purified n-3FAs daily for 10 weeks is a beneficial supplement for decreasing TG without any increase in LDL-C, apo-B or MDA. Administration of 500 mg VitC for more than 10 weeks might decrease significantly TC and apo-B in hyperlipidemic patients.  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