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   1472篇
  免费   102篇
  国内免费   3篇
耳鼻咽喉   40篇
儿科学   37篇
妇产科学   39篇
基础医学   244篇
口腔科学   50篇
临床医学   120篇
内科学   339篇
皮肤病学   52篇
神经病学   80篇
特种医学   51篇
外科学   194篇
综合类   2篇
预防医学   125篇
眼科学   7篇
药学   72篇
  1篇
中国医学   1篇
肿瘤学   123篇
  2023年   8篇
  2022年   15篇
  2021年   34篇
  2020年   26篇
  2019年   32篇
  2018年   34篇
  2017年   23篇
  2016年   30篇
  2015年   29篇
  2014年   35篇
  2013年   40篇
  2012年   81篇
  2011年   70篇
  2010年   49篇
  2009年   42篇
  2008年   70篇
  2007年   85篇
  2006年   77篇
  2005年   72篇
  2004年   61篇
  2003年   83篇
  2002年   53篇
  2001年   45篇
  2000年   43篇
  1999年   36篇
  1998年   18篇
  1997年   15篇
  1996年   14篇
  1995年   10篇
  1994年   11篇
  1993年   7篇
  1992年   28篇
  1991年   16篇
  1990年   19篇
  1989年   10篇
  1988年   17篇
  1987年   13篇
  1986年   15篇
  1985年   16篇
  1984年   9篇
  1983年   7篇
  1981年   11篇
  1980年   11篇
  1979年   11篇
  1978年   11篇
  1974年   9篇
  1973年   9篇
  1967年   8篇
  1933年   7篇
  1932年   6篇
排序方式: 共有1577条查询结果,搜索用时 15 毫秒
41.
A number of risk factors based upon mostly retrospective surgical data, have been formulated in order to identify impending pathological fractures of the femur from low-risk metastases. We have followed up patients taking part in a randomised trial of radiotherapy, prospectively, in order to determine if these factors were effective in predicting fractures. In 102 patients with 110 femoral lesions, 14 fractures occurred during follow-up. The risk factors studied were increasing pain, the size of the lesion, radiographic appearance, localisation, transverse/axial/circumferential involvement of the cortex and the scoring system of Mirels. Only axial cortical involvement >30 mm (p = 0.01), and circumferential cortical involvement >50% (p = 0.03) were predictive of fracture. Mirels' scoring system was insufficiently specific to predict a fracture (p = 0.36). Our results indicate that most conventional risk factors overestimate the actual occurrence of pathological fractures of the femur. The risk factor of axial cortical involvement provides a simple, objective tool in order to decide which treatment is appropriate.  相似文献   
42.
OBJECTIVE: To determine the absorption, excretion and metabolism of kaempferol in humans. DESIGN: A pharmacokinetic study of kaempferol from endive over 24 h. SUBJECTS: Four healthy males and four healthy females. RESULTS: Kaempferol, from a relatively low dose (9 mg), was absorbed from endive with a mean maximum plasma concentration of 0.1 microM, at a time of 5.8 h, indicating absorption from the distal section of the small intestine and/or the colon. Although a 7.5-fold interindividual variation between the highest and lowest maximum plasma concentration was observed, most individuals showed remarkably consistent pharmacokinetic profiles. This contrasts with profiles for other flavonoids that are absorbed predominantly from the large intestine (eg rutin). An average of 1.9% of the kaempferol dose was excreted in 24 h. Most subjects also showed an early absorption peak, probably corresponding to kaempferol-3-glucoside, present at a level of 14% in the endive. Kaempferol-3-glucuronide was the major compound detected in plasma and urine. Quercetin was not detected in plasma or urine indicating a lack of phase I hydroxylation of kaempferol. CONCLUSIONS: Kaempferol is absorbed more efficiently than quercetin in humans even at low oral doses. The predominant form in plasma is a 3-glucuronide conjugate, and interindividual variation in absorption and excretion is low, suggesting that urinary kaempferol could be used as a biomarker for exposure.  相似文献   
43.
BACKGROUND: The mucopolysaccharidosis (MPS) are a group of inherited metabolic disorders resulting from the deficiency of the enzyme responsible for intralysosomal catabolism of glycosaminoglycans (GAGs). GAGs are progressively accumulated in multiple tissues and released into the corporal fluids. The first laboratory approximation to MPS diagnosis is the identification of an increased urinary GAG excretion. For this, several semiquantitative and quantitative methods have been developed. The aim of this retrospective statistical study was to evaluate the reliability of MPS urine screening for the semiquantitative Berry spot test (BST) and the quantitative dimethylmethylene blue test (DMB). METHODS: The 24-h-urine samples (n = 246) were tested through BST, DMB, and for GAG excretion pattern by one-dimensional electrophoresis or thin layer chromatography. RESULTS: the 204 samples that demonstrated a normal GAG excretion pattern were considered as non-MPS samples. Forty-two samples presented an abnormal GAG excretion pattern. Enzyme analysis was available for 31 out of 42 patients (31/42), confirming that all were affected by MPS. Urinary GAG concentrations of MPS patients by DMB were increased 1.04- to 7.1-folds, compared to age-related normal levels. The sensitivity was 100% for DMB and 93.6% for BST. DMB demonstrated a specificity of 74.5%, while BST a specificity of 53.9%. The specificity of MPS screening increased to 84.3%, considering conjunctly DMB and BST. CONCLUSION: The DMB is a sensitive method, however, inclusion of BST could increase the specificity of MPS urine screening.  相似文献   
44.
Epidemiologic studies suggest that exposure to sunlight is the primary etiologic agent for basal cell carcinoma. Formation of UV-induced DNA damage is believed to be a crucial event in the process leading to skin cancer. In this study, repair of photoproducts in DNA was followed in the skin of patients with basal cell carcinoma and control subjects. The subjects were exposed to 800 J/m(2) Commission Internationale de 1'Eclairag of solar-simulating radiation on buttock skin. Biopsies were taken at 0 hour, 24 hours, and 3 weeks after the exposure. Two cyclobutane pyrimidine dimers, TT=C and TT=T, were measured using a sensitive (32)P-postlabeling assay. Initial levels of both TT=C and TT=T differed between individuals in both groups. The levels of TT=T in patients with basal cell carcinoma and controls were similar (9.9 +/- 4.0 and 9.2 +/- 2.9 products per 10(6) normal nucleotides), whereas the level of TT=C was significantly lower in controls than in patients with basal cell carcinoma (6.2 +/- 3.1 versus 10.9 +/- 4.5 products per 10(6) normal nucleotides). The fractions of TT=T remaining after 24 hours and 3 weeks were significantly higher in patients with basal cell carcinoma (72% and 11%) compared with controls (48% and 5%). A slower removal in patients with basal cell carcinoma than in controls was indicated also for TT=C (52% versus 42% remaining at 24 hours); however, the difference between groups was not significant. When including data from our previously reported small-scale study, the fraction of dimers remaining at 24 hours was significantly higher in patients with basal cell carcinoma for both TT=C and TT=T. The data suggest that patients with basal cell carcinoma have a reduced capacity to repair UV-induced DNA lesions.  相似文献   
45.
The purpose of this research was to review the literature on home blood pressure measurement (HBPM) and to provide recommendations regarding HBPM assessment. Observational studies on HBPM, published after 1992, as identified by PubMed, EMBASE, and Cochrane literature searches were reviewed. Studies were selected if they met the following criteria: 1) self-measurements had been performed with validated devices; 2) measurement procedures were described in sufficient detail; and 3) papers clearly explained how final HBPM results were calculated upon which conclusions and/or treatment decisions were based. Office blood pressure measurement (OBPM) yields higher blood pressure values than HBPM. For systolic blood pressure, differences between OBPM and HBPM increase with age and the height of office pressure. Differences also tend to be greater in men than in women and greater in patients without than in those with antihypertensive treatment. Furthermore, HBPM can diagnose normotension with almost absolute certainty; it correlates better with target organ damage and cardiovascular mortality than OBPM, it enables prediction of sustained hypertension in patients with borderline hypertension, and it proves to be an appropriate tool for assessing drug efficacy. Despite some limitations and although more data are needed, HBPM is suitable for routine clinical practice.  相似文献   
46.
Background. Several methods of randomization are available to create comparable intervention groups in a study. In the HOMERUS-trial, we compared the minimization procedure with a stratified and a non-stratified method of randomization in order to test which one is most appropriate for use in clinical hypertension trials. A second objective of this article was to describe the baseline characteristics of the HOMERUS-trial. Methods. The HOMERUS population consisted of 459 mild-to-moderate hypertensive subjects (54% males) with a mean age of 55 years. These patients were prospectively randomized with the minimization method to either the office pressure (OP) group, where antihypertensive treatment was based on office blood pressure (BP) values, or to the self-pressure (SP) group, where treatment was based on self-measured BP values. Minimization was compared with two other randomization methods, which were performed post-hoc: (i) non-stratified randomization with four permuted blocks, and (ii) stratified randomization with four permuted blocks and 16 strata. In addition, several factors that could influence outcome were investigated for their effect on BP by 24-h ambulatory blood pressure monitoring (ABPM). Results. Minimization and stratified randomization did not lead to significant differences in 24-h ABPM values between the two treatment groups. Non-stratified randomization resulted in a significant difference in 24-h diastolic ABPM between the groups. Factors that caused significant differences in 24-h ABPM values were: region, centre of patient recruitment, age, gender, microalbuminuria, left ventricular hypertrophy and obesity. Conclusion. Minimization and stratified randomization are appropriate methods for use in clinical trials. Many outcome factors should be taken into account for their potential influence on BP levels. Recommendation. Due to the large number of potential outcome factors that can influence BP levels, minimization should be the preferred method for use in clinical hypertension trials, as it has the potential to randomize more outcome factors than stratified randomization.  相似文献   
47.
PURPOSE: The aim of this study was to evaluate the results of 10 years dynamic sentinel node biopsy experience in penile carcinoma at our institute. PATIENTS AND METHODS: 140 patients with clinically node-negative groins were prospectively included. Lymphoscintigraphy was performed after injection of 99mTechnetium-nanocolloid around the primary tumour. The sentinel node was intraoperatively identified with the aid of patent blue dye and a gamma ray detection probe. Lymph node dissection was performed only if sentinel node metastasis was found. Median follow-up was 52 months (range 5-129). RESULTS: Lymphoscintigraphy visualized at least 1 sentinel node in 138 patients. Sentinel node metastasis was found in 37 inguinal regions of 31 patients. The sentinel node was the only tumour-positive node in 78% (29/37) of the dissection specimens. Complications occurred in 8% (17/206) of the operated groins. False-negative results were encountered in 6 patients resulting in a false-negative rate of 16% (6/37 patients). 5-year disease-specific survival was 96% and 66% for patients with a tumour-negative sentinel node and tumour-positive sentinel node, respectively (p=0.001). CONCLUSION: Dynamic sentinel node biopsy in penile carcinoma is of important diagnostic, prognostic, and therapeutic value at the cost of only minor morbidity.  相似文献   
48.
49.
50.

Background   

There is increasing recognition of the importance of psychiatric vocational rehabilitation (PVR) programmes in helping individuals with severe mental illnesses to find and secure jobs. However, little is known concerning the factors related to PVR outcomes.  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