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   3319篇
  免费   255篇
  国内免费   7篇
耳鼻咽喉   15篇
儿科学   96篇
妇产科学   47篇
基础医学   570篇
口腔科学   16篇
临床医学   375篇
内科学   706篇
皮肤病学   100篇
神经病学   454篇
特种医学   90篇
外国民族医学   1篇
外科学   273篇
综合类   9篇
预防医学   241篇
眼科学   43篇
药学   218篇
中国医学   2篇
肿瘤学   325篇
  2023年   28篇
  2022年   51篇
  2021年   110篇
  2020年   72篇
  2019年   98篇
  2018年   106篇
  2017年   79篇
  2016年   76篇
  2015年   102篇
  2014年   118篇
  2013年   132篇
  2012年   265篇
  2011年   270篇
  2010年   142篇
  2009年   143篇
  2008年   222篇
  2007年   225篇
  2006年   191篇
  2005年   195篇
  2004年   171篇
  2003年   161篇
  2002年   124篇
  2001年   50篇
  2000年   44篇
  1999年   23篇
  1998年   24篇
  1997年   14篇
  1996年   15篇
  1995年   8篇
  1994年   8篇
  1993年   8篇
  1992年   18篇
  1991年   26篇
  1990年   28篇
  1989年   21篇
  1988年   13篇
  1987年   11篇
  1986年   13篇
  1985年   16篇
  1984年   12篇
  1983年   14篇
  1981年   10篇
  1980年   7篇
  1979年   9篇
  1977年   9篇
  1975年   9篇
  1974年   10篇
  1972年   7篇
  1970年   8篇
  1965年   7篇
排序方式: 共有3581条查询结果,搜索用时 15 毫秒
1.
OBJECTIVE: Respiratory muscle endurance of able-bodied persons, assessed by normocapnic hyperpnoea at 70% of their maximal voluntary ventilation, usually ranges from 10 to 20 minutes. The aim of this study was to determine the level of ventilation that patients with paraplegia and tetraplegia can sustain for 10-20 minutes to later be used as the guideline for respiratory muscle endurance training. DESIGN: Pilot study; cross-over setting. SUBJECTS: Two groups, 8 patients with paraplegia and 6 with tetraplegia. METHODS: Respiratory muscle endurance tests were performed at 3 different intensities of normocapnic hyperpnoea, i.e. 20%, 40% and 60% maximal voluntary ventilation. Subjects performed partial re-breathing from a bag to assure normocapnia. Respiratory endurance was separately analysed for patients with paraplegia and tetraplegia. RESULTS: Mean respiratory endurance times were 46.0, 18.9 and 4.2 minutes at 20%, 40% and 60% maximal voluntary ventilation in patients with tetraplegia and 51.8, 38.8 and 12.2 minutes in patients with paraplegia. The duration differed significantly at 60% maximal voluntary ventilation between the groups. CONCLUSION: Minute ventilation to perform respiratory muscle endurance training can be set at around 40% of maximal voluntary ventilation for patients with tetraplegia and around 60% of maximal voluntary ventilation for patients with paraplegia, as these levels can be sustained for 10-20 minutes.  相似文献   
2.
Comparison of polymorphic sites such as single nucleotide polymorphisms (SNPs) within a gene between cases and controls may be useful for establishing a role of this gene in disease susceptibility. The approach includes two steps: the first step is the discovery of the different SNPs within the candidate gene and the second step is the association testing per se that can be done on the entire set of sites discovered or on a subset of these sites only. Selecting a subset of sites may increase the power to detect the association with the candidate gene since a smaller number of tests would then be performed. We proposed a strategy to select sites within a candidate gene and applied it on the Genetic Analysis Workshop 12 candidate gene data. Using these selected sites, we detected an association with candidate genes 1 and 6. © 2001 Wiley‐Liss, Inc.  相似文献   
3.
BACKGROUND: Acne is a multifactorial disease exhibiting distinct clinical presentations. Among them, the catamenial type is a matter of concern for young women. Some oral contraceptives may help without, however, clearing the skin condition. AIM: The present open study aimed at evaluating the effect of overnight applications of a paste made of petrolatum,15% zinc oxide and 0.25% miconazole nitrate. METHOD: The split-face trial was conducted in 35 women. A non-medicated cream was used as control. Clinical evaluations and biometrological assessments on cyanoacrylate follicular biopsies were performed monthly for 3 months. Comedometry and the density in autofluorescent follicular casts were used as analytical parameters. In addition, the five most severe cases at inclusion were tested at the completion of the study for follicular bacterial viability using dual flow cytometry. RESULTS: Compared with baseline and to the control hemi-face, the medicated paste brought significant improvement of acne. The number of papules and their redness were reduced beginning with the first treatment phase. A reduction in the follicular fluorescence was yielded beginning with the second treatment phase. The ratios between injured and dead bacteria, on the one hand, and live bacteria, on the other hand were significantly increased at completion of the study. CONCLUSION: A miconazole paste applied for 1 week at the end of the ovarian cycle has a beneficial effect on catamenial acne.  相似文献   
4.
The authors reported here a case of dominant form of osteopetrosis. The patient was a 28 years old man hospitalized for a mandibular osteitis consecutive to a tooth extraction. The clinical examination detected a splenomegaly. The laboratory tests showed anemia and thrombopenia. A radiographic skeletal survey detected a typical generalized osteocondensation. The authors pointed out the radiologic signs of the disease and underscored the difficulties in managing osteomyelitis of the jaw in such patients.  相似文献   
5.
The risk of non-A, non-B hepatitis transmission by an intravenous immunoglobulin (IVIG) preparation was assessed in a prospective multicenter trial in 68 patients with primary immunodeficiency disorders (40 children or adolescents and 28 adults). During the 4-week prestudy evaluation period the clinical examinations and liver function tests including alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase, alkaline phosphatase, and bilirubin were normal in all patients. The treatment consisted of three infusions of 200 mg IVIG (pH 4; pepsin procedure) per kilogram body weight at 2-week intervals. During the observation period of 24 weeks following the first infusion of the study IVIG, the patients were monitored at regular time intervals. No clinical and laboratory signs of hepatitis or liver dysfunction were noticed. All patients completed the study. In 5 patients, one isolated alanine aminotransferase value and in another patient one gamma-glutamyl transpeptidase value were moderately elevated, but always below 2.5 times the upper limit of the reference range. Similar isolated and transient elevations were observed for aspartate aminotransferase and alkaline phosphatase. It was concluded that the IVIG preparation did not transmit non-A, non-B hepatitis or other viral liver diseases.  相似文献   
6.
7.
A cross-sectional survey investigated the relationship between the number of previous depressive episodes and life events, testing the kindling hypothesis, in a sample of 13,377 treated patients with unipolar depression. A linear decline of average life events exposure is observed for more frequent past episodes, even when age, gender and severity are taken into account.  相似文献   
8.
Since there is strong evidence of a preferential LDL accumulation in tumor cells, LDL might be of interest for tumor imaging. We have tested the ability of 99mTc-LDL in tumor imaging with B16-melanoma-bearing mice as a model for further applications in human studies. The LDL fixation rate was higher with 99mTc-labeled LDL than with 125I labeled LDL. Since technetium-99m remains trapped in the cells, 99mTc-LDL is a well-adapted radioligand because of information given by this radiotracer on the receptor metabolism. We observed that, at early growth stages, the tumor took up the LDL at a maximal rate, suggesting differences in cholesterol metabolism as a function of tumor growth. Accumulation of label in the tumor area was perfectly observable in tumor-bearing mice on scintigraphic images. Computerized quantification of the regions of interest (as well as biodistribution studies including killing of the animals) showed a 1.81 -fold increase in uptake by the tumor as compared to the liver and a 28-fold increase as compared with corresponding normal tissue (muscle of the left leg) at day 8 of tumor growth. These data give strong support to the value of this non-invasive method in visualizing and quantifying the tissue LDL uptake in vivo, including the precise information provided by nuclear scintigraphy on the distribution of the radiolabeled LDL in the different tissues. 99mTc-LDL could be an efficient tool for further diagnostic or therapeutic exploration in cancer patients.  相似文献   
9.
10.
INTRODUCTION: Spinal cord compression due to meningeal thickening is a rare occurrence in shunted patients. Because of the long delay to clinical onset, this complication has not been identified as yet. AIMS: We report on nine cases of shunt-related progressive myelopathy due to meningeal thickening (SPMMT). MATERIALS AND METHODS: We reviewed our database of shunted children, for cases having developed progressive tetraparesis due to cervical meningeal thickening. RESULTS: We identified nine observations of SPMMT, eight of these with hydrocephalus due to neonatal meningitis; the last case had Dandy-Walker malformation shunted at birth and suffered postoperative meningitis. The age of clinical onset of myelopathy was between 6 and 20 years (median 12.8). All patients presented with slowly progressive walking difficulties with falls and no spinal pain. Magnetic resonance imaging (MRI) showed typically a thickened dura mater with collapse of the arachnoid space, compensatory expansion of the epidural fat, and T2 hyperintensity in the spinal cord. We operated on seven patients for surgical decompression and arachnoidolysis: One died postoperatively because of shunt malfunction, and two others died later of complications of tetraplegia. Three patients were aggravated after surgery, three experienced partial improvement, but one of these subsequently deteriorated again. CONCLUSION: SPMMT appears to be a novel and well-defined clinical and pathological entity; its pathological and radiological features are stereotyped; however, the diagnosis is delayed because of the slow pace of the disease. Although surgical decompression may be the only option, its results were poor in our experience; earlier surgery might improve this grim prognosis.  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