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   1995篇
  免费   66篇
  国内免费   17篇
耳鼻咽喉   25篇
儿科学   37篇
妇产科学   33篇
基础医学   150篇
口腔科学   29篇
临床医学   106篇
内科学   541篇
皮肤病学   16篇
神经病学   102篇
特种医学   51篇
外科学   514篇
综合类   7篇
预防医学   70篇
眼科学   8篇
药学   111篇
中国医学   5篇
肿瘤学   273篇
  2023年   8篇
  2022年   9篇
  2021年   42篇
  2020年   25篇
  2019年   30篇
  2018年   33篇
  2017年   30篇
  2016年   44篇
  2015年   48篇
  2014年   48篇
  2013年   77篇
  2012年   106篇
  2011年   126篇
  2010年   63篇
  2009年   66篇
  2008年   122篇
  2007年   141篇
  2006年   119篇
  2005年   134篇
  2004年   115篇
  2003年   119篇
  2002年   125篇
  2001年   32篇
  2000年   32篇
  1999年   36篇
  1998年   30篇
  1997年   20篇
  1996年   22篇
  1995年   13篇
  1994年   7篇
  1992年   14篇
  1991年   22篇
  1990年   24篇
  1989年   13篇
  1988年   20篇
  1987年   15篇
  1986年   18篇
  1985年   17篇
  1984年   12篇
  1983年   21篇
  1981年   7篇
  1980年   10篇
  1979年   5篇
  1978年   4篇
  1977年   7篇
  1974年   4篇
  1969年   4篇
  1968年   5篇
  1967年   4篇
  1966年   5篇
排序方式: 共有2078条查询结果,搜索用时 281 毫秒
131.
OBJECTIVE: The objective of this study was to investigate the predictive factors of premature rupture of the membranes (preterm PROM). METHODS: The study was undertaken with cervical secretions collected from 72 consenting singleton pregnant women between 20 and 33 weeks of gestation. The levels of interleukin (IL) 1alpha, IL-1beta, IL-6, IL-8, matrix metalloproteinase (MMP) 1, MMP-2, MMP-9, tissue inhibitors of matrix metalloproteinase (TIMP) 1, TIMP-2, granulocyte elastase, and fetal fibronectin in cervical diluted specimens were measured by immunoassay, and the uterine cervix was assessed by transvaginal ultrasonography. Demographic, obstetric, clinical, neonatal, and laboratory data were analyzed by univariate analysis, multiple logistic regression, and receiver operator characteristic curve analysis. RESULTS: Preterm PROM occurred in 6 women, and 63 women delivered at term. Multiple logistic regression analysis indicated a significant independent association with preterm PROM for the cervical IL-6 levels and cervical length. The receiver operator characteristic curve analysis revealed that an IL-6 level of >/=240 pg/ml in cervical secretions and a cervical length of 相似文献   
132.
BACKGROUND: To investigate the relationship between preoperative serum CA 125 levels and para-aortic lymph node (PAN) metastasis as determined by systematic pelvic and para-aortic lymph node dissection in endometrial carcinoma. METHODS: This study included 180 patients (n = 55, premenopausal; n = 125, postmenopausal) with endometrial carcinoma treated by complete surgical staging. Cut-off values of preoperative serum CA 125 levels for PAN metastasis were determined by receiver characteristic curve (ROC) analysis. Logistic regression analysis was used to determine independent predictors for PAN metastasis. RESULTS: The median serum CA 125 levels of patients with PAN metastasis were significantly higher than the levels of those with no metastasis in both premenopausal and postmenopausal groups. Based on ROC analysis, we could determine four cut-off values (70 and 210 U/mL for premenopausal patients, 20 and 60 U/mL for postmenopausal patients) and categorize the serum CA 125 levels into low, moderate and high groups. By logistic regression analysis, the CA 125 level and nuclear grade were found to be significant predictors of PAN metastasis, respectively. Using this model, the patients were stratified into three risk groups. The probabilities of PAN metastasis for patients in the low-risk, intermediate-risk and high-risk groups were less than 2%, 2-25% and more than 50%, respectively. CONCLUSIONS: Serum CA 125 levels and nuclear grade are important risk factors for PAN metastasis in endometrial carcinoma.  相似文献   
133.
BACKGROUND: The aim of this study was to identify the independent histopathologic prognostic factors for patients with cervical carcinoma treated with radical hysterectomy including paraaortic lymphadenectomy. METHODS: A total of 187 patients with stage IB to IIB cervical carcinomas treated with radical hysterectomy and systematic retroperitoneal lymphadenectomy were retrospectively analyzed. The median follow-up period was 83 months. Cox regression analysis was used to select independent prognostic factors. RESULTS: Using multivariate Cox regression analysis, lymph node (LN) status (negative vs. metastasis to pelvic nodes except for common iliac nodes vs. common iliac/paraaortic node metastasis), histopathologic parametrial invasion, lymph-vascular space invasion (LVSI), and histology of pure adenocarcinoma were found to be independently related to patients' poor survival. For patients who had a tumor histologically confined to the uterus and have neither parametrial invasion nor lymph node metastasis, LVSI was the most important prognostic factor, and histologic type, depth of cervical stromal invasion, and tumor size were not related to survival. The survival of patients with a tumor extending to parametrium or pelvic lymph node(s) was adversely affected by histology of pure adenocarcinoma. When the tumor extended to common iliac or paraaortic nodes, patients' survival became quite poor irrespective of LVSI or histologic type of pure adenocarcinoma. Patients' prognosis could be stratified into low risk (patients with a tumor confined to the uterus not associated with LVSI: n = 80), intermediate risk (patients with a tumor confined to the uterus associated with positive LVSI, and patients with squamous/adenosquamous carcinoma associated with pelvic lymph node metastasis or parametrial invasion: n = 86), and high risk (patients with pure adenocarcinoma associated with pelvic lymph node metastasis or parametrial invasion, and patients with common iliac/paraaortic node metastasis: n = 21) with an estimated 5-year survival rate of 100 +/- 0 (mean +/- SE)%, 85.5 +/- 3.9%, and 25.1 +/- 9.7%, respectively. CONCLUSIONS: LN status, parametrial invasion, LVSI, and histology of pure adenocarcinoma are important histopathologic prognostic factors of cervical carcinoma treated with radical hysterectomy and systematic retroperitoneal lymphadenectomy. Prognosis for patients with cervical carcinoma may be stratified by combined analysis of these histopathologic prognostic factors. Postoperative therapy needs to be individualized according to these prognostic factors and validated for its efficacy using randomized clinical trials.  相似文献   
134.
We treated three thrombophilia-complicated pregnant women (two antiphospholipid antibody syndrome, one protein C deficiency) with low molecular weight heparin (dalteparin). All three pregnancies including one twin pregnancy ended in live births without a decrease in bone mineral density. This treatment modality was effective and safe preventing thrombosis during their pregnancies.  相似文献   
135.
One of the serious problems that occurs after cardiopulmonary resuscitation is brain posthypoxic/ischemic deoxygenation. However, there has been no report concerning the effect of isoflurane (ISO) on the brain oxygenation during hypoxia-reoxygenation in relation to cell adhesion molecules (CD11b) in polymorphonuclear leukocyte. Rats were anesthetized with a low concentration of ISO (0.5 MAC: low ISO) or high concentration of ISO (1.5 MAC: high ISO) and brain oxygenation was detected by near infrared spectroscopy during 10-min hypoxia (5% O(2)) and a subsequent 120-min reoxygenation period. Hypoxia induced a decrease in oxyhemoglobin (HbO(2)) and an increase in deoxyhemoglobin (Hb). Reoxygenation induced a significant decrease in total hemoglobin (tHb) and HbO(2) with low ISO, but not with high ISO. The changes in Hb were minimal during reoxygenation in both groups. CD11b increased during reoxygenation with low ISO anesthetization, but not with high ISO. A significant negative correlation was observed between CD11b and two of the measured oxyparameters, HbO(2) and tHb, during reoxygenation at low ISO, but not at high ISO. These findings suggest that brain deoxygenation during hypoxia-reoxygenation is partly related to the expression of CD11b. We conclude that ISO modifies the brain circulation at least in part through attenuating the expression of CD11b during hypoxia-reoxygenation.  相似文献   
136.
CYP1B1 gene in endometrial cancer   总被引:4,自引:0,他引:4  
Metabolic activation of estradiol has been shown to be a key factor in endometrial carcinogenesis. 4-hydroxy estrogens (CYP1B1 metabolites) received particular attention because of their causative role in malignant transformation of various organs including endometrium. CYP1B1 displays the highest level of expression in endometrium. 4-hydroxy estrogens can bind to DNA via their quinone metabolites and cause oxidative damage in endometrial cancer. Moreover, the 4-hydroxy estrogens bind to the estrogen receptor and have estrogenic effects on target tissues. Six polymorphisms of the CYP1B1 gene have been described of which four result in amino acid substitutions; 1-13C-->T, codon 48C-->G, codon 119G-->T, codon 432C-->G, codon 449T-->C and codon 453A-->G. The polymorphisms on exons 2 and 3 have significant effects on the catalytic function of CYP1B1. Polymorphisms on specific regions of CYP1B1 gene result in hyperactivation of the protein and can lead to a higher susceptibility in the incidence of various cancers. Thus, inherited alterations in CYP1B1 hydroxylation activity may be associated with significant changes in estrogen metabolism and, thereby, may possibly explain inter-individual differences in endometrial cancer risk associated with estrogen-mediated carcinogenesis.  相似文献   
137.
BACKGROUND: Although altered nonlinear heart rate dynamics predicts death in patients with coronary artery disease (CAD), its prognostic value in chronic hemodialysis patients with CAD is unknown. METHODS: We analyzed 24-hour electrocardiogram for nonlinear heart rate dynamics and heart rate variability in a retrospective cohort of 81 chronic hemodialysis patients with CAD. RESULTS: During a follow-up period of 31 +/- 20 months, 19 cardiac and 8 noncardiac deaths were observed. Cox hazards model, including diabetes, left ventricular ejection fraction, and the number of diseased coronary arteries, revealed that abnormal alpha2 (defined as both increase and decrease in alpha2 because of its J curve relationship with cardiac mortality), decreased approximate entropy and decreased heart rate variability (triangular index and ultra-low frequency power) were significant and independent predictors of cardiac death. No significant and independent predictive power for noncardiac death was observed in either the heart rate dynamics or the heart rate variability measures. The predictive power of alpha2 and approximate entropy was independent of that of triangular index and ultra-low frequency power. Combinations of two categories of measures improved the predictive accuracy; overall accuracy of approximate entropy + ultra-low frequency power for cardiac death was 87%. CONCLUSION: Altered nonlinear heart rate dynamics are independent predictors of cardiac death in chronic hemodialysis patients with CAD and their combinations with decreased heart rate variability provide clinically useful markers for risk stratification.  相似文献   
138.
BACKGROUND: In small mesenteric arteries, endothelium-derived hyperpolarizing factor (EDHF) in addition to endothelium-derived relaxing factors (EDRFs) including NO plays an important role in acetylcholine-induced vasodilation. It has been reported that EDRFs play an important role in alpha(1)-adrenoceptor agonist-induced oscillatory vasomotion and in limiting vasoconstrictor response to the agonists; however, contribution of EDHF to the alpha(1)-agonist-induced oscillation is unknown. METHODS: Rat small mesenteric arteries were isolated and cannulated at each end with a glass micropipette. The vessels were immersed in a bath (37 degrees C) containing physiologic saline solution. Changes in vessel diameter were measured using an optical density video detection system. RESULTS: Denudation of the endothelium and inhibition of NO synthesis caused a leftward shift in the concentration-response relation for phenylephrine in the mesenteric arteries, whereas inhibition of cyclooxygenase by indomethacin had no effect. Blockade of Ca2+-activated K+ (K(Ca)) channels by charybdotoxin and apamin caused a further leftward shift in the concentration-response relation in the vessels pretreated with Nomega-nitro-l-arginine methylester and indomethacin. Phenylephrine at concentrations higher than 10(-6) m caused endothelium-dependent oscillatory vasomotion, which was reduced but not abolished after combined inhibition of the cyclooxygenase and NO synthase pathways. However, the K(Ca) channel blockers completely abolished the remaining component of oscillation. CONCLUSIONS: Endothelially-derived NO is an important modulator of sustained agonist-induced vasoconstriction. NO, as well as endothelially-derived cyclooxygenase products and EDHF, also contribute significantly to phenylephrine-induced oscillatory vasomotion.  相似文献   
139.
We have experienced two cases of interstitial nephritis with Sj?gren's syndrome successfully treated by steroid therapy. Case 1. A 50-year-old woman was admitted because of rash and arthralgia of the limb. Although her renal function was normal, serum IgG was extremely high and gallium-67 scintigrams indicated abnormal uptake in both kidneys with swelling on CT scans. Renal biopsy specimens showed a patchy dense interstitial infiltration of lymphocytes, monocytes and partly plasma cells with tubular cell atrophy. To suppress an excessive immune reaction, oral prednisolone was administrated at a dose of 30 mg/day. Six weeks after inception of the therapy, re-biopsy specimens showed a decrease in interstitial infiltration, particularly plasma cells, and interstitial fibrosis did not progress. After 8 weeks, the serum IgG level was normalized. Case 2. A 57-year-old woman was found to have renal involvement(serum creatinine level: 2.2 mg/dl) and anemia. Clinical findings suggested primary Sj?gren's syndrome with renal tubular acidosis. Renal biopsy specimens showed a moderate to severe interstitial infiltration of inflammatory cells. After inception of steroid therapy(prednisolone 40 mg/day), renal involvement and renal anemia gradually improved. The renal function has been kept stable(serum creatinine level: 1.5 mg/dl) for 9 years by low-dose steroid therapy. These two cases suggest that steroid therapy plays two important roles: controlling of the acute immune reaction that causes renal fibrosis to progress in case 1, and long-term preservation of the renal function by the continuous use of low-doses in case 2.  相似文献   
140.
BACKGROUND: The associations between supplement use and certain demographics, lifestyles, health characteristics, and dietary intakes have not been studied in a large population in non-Western societies. The objective of our study was to investigate the association between supplement use and demographics, lifestyles, health characteristics, and dietary intake in a population-based cohort study in Japan. METHODS: Subjects were the 78 531 participants (45-74 years) who completed a self-administered questionnaire in 1995 or 1998 in a 5-year follow-up survey by the Japan Public Health Center-based prospective Study on cancer and cardiovascular disease. The questionnaire included enquiries about supplement use, occupation, height, weight, smoking, alcohol, physical activity, dietary behaviours, working hours, subjective stress, as well as intakes for 138 foods. RESULTS: The supplement users were likely to have formerly smoked or never smoked. Female supplement users were likely to consume alcohol moderately. The prevalence of users was higher in the elderly, the self-employed, those with lower body mass index, greater physical activity, lower frequency of eating prepared food, higher frequency of eating out, and higher stress level in both sexes after mutual adjustment. Mean intakes of energy and nutrients were lower for users than for non-users. CONCLUSION: The demographics, lifestyles, health characteristics, and dietary intakes may need to be adjusted when evaluating the effect of dietary supplements on disease because they can become potential confounding factors.  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