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   2806篇
  免费   185篇
  国内免费   15篇
耳鼻咽喉   9篇
儿科学   31篇
妇产科学   59篇
基础医学   406篇
口腔科学   12篇
临床医学   347篇
内科学   616篇
皮肤病学   22篇
神经病学   330篇
特种医学   119篇
外科学   351篇
综合类   4篇
一般理论   6篇
预防医学   148篇
眼科学   38篇
药学   191篇
中国医学   9篇
肿瘤学   308篇
  2024年   3篇
  2023年   24篇
  2022年   43篇
  2021年   96篇
  2020年   47篇
  2019年   82篇
  2018年   93篇
  2017年   80篇
  2016年   70篇
  2015年   101篇
  2014年   130篇
  2013年   173篇
  2012年   244篇
  2011年   261篇
  2010年   151篇
  2009年   116篇
  2008年   219篇
  2007年   203篇
  2006年   173篇
  2005年   188篇
  2004年   149篇
  2003年   137篇
  2002年   119篇
  2001年   13篇
  2000年   8篇
  1999年   12篇
  1998年   21篇
  1997年   13篇
  1996年   14篇
  1995年   3篇
  1994年   5篇
  1993年   4篇
  1992年   3篇
  1991年   3篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
排序方式: 共有3006条查询结果,搜索用时 15 毫秒
101.
Peroxisome proliferator-activated receptors (PPARs) regulate storage and catabolism of fats and carbohydrates. PPARgamma activity increases insulin sensitivity and adipocyte differentiation at the expense of adipogenesis and weight gain. The goal of this study was to 1) clone the promoter of the human adipocyte fatty acid binding protein (aP2) gene, namely fatty acid-binding protein-4, 2) characterize its pharmacological regulation, and 3) determine its putative predictability for adipogenesis. Among the selected PPAR agonists, rosiglitazone and pioglitazone displayed the highest maximal efficacy (E(max)) on reporter-gene assays in COS-7 cells cotransfected by either a galactosidase 4-response element-based or a human aP2 promoter-based Luc reporter vector, along with either chimeric or full-length human PPAR expression plasmids. The non-subtype-selective 2-(4-[2-(3-[2,4-difluorophenyl]-1-heptylureido)ethyl]phenoxy)-2-methyl-butyric acid (GW-2331) and the compounds [4-[3-(4-acetyl-3-hydroxy-2-propylphenoxy)-propoxyl]phenoxy]-acetic acid (L-165041), (4-((2S,5S)-5-(2-(bis(phenylmethyl)amino)-2-oxoethyl)-2-heptyl-4-oxo-3-thiazolidinyl)butyl)-benzoic acid (GW-0072), and indomethacin behaved as partial agonists relative to pioglitazone in full-length human aP2-PPARgamma2. Beyond their partial PPARgamma agonist properties, these compounds elicited a lower maximal up-regulation of mouse aP2 mRNA in 3T3-L1 adipocytes as compared with pioglitazone; these properties paralleled a time-dependent increase in neutral lipids. By contrast, the selective PPARalpha agonist 2,2-dichloro-12-(4-chlorophenyl)dodecanoic acid (BM-17.0744) neither stimulated the human aP2-PPARalpha promoter reporter-gene assay, thus demonstrating a specific interaction between PPARgamma and the aP2 promoter, nor affected lipogenesis in 3T3-L1 cells. Altogether, these data characterized a functional promoter of the human aP2 gene; its in vitro pharmacological regulation in PPARgamma-mediated reporter-gene assay may represent an interesting complement or an alternative to time-consuming procedures aiming at discriminating PPAR ligands with low lipogenic properties.  相似文献   
102.
Freyssin C, Verkindt C, Prieur F, Benaich P, Maunier S, Blanc P. Cardiac rehabilitation in chronic heart failure: effect of an 8-week, high-intensity interval training versus continuous training.ObjectiveTo compare the effects of an 8-week, high-intensity interval training protocol versus continuous training.DesignRandomized controlled trial.SettingCardiac rehabilitation center.ParticipantsPatients (N=26; mean age ± SD, 54±12y) with chronic heart failure were enrolled in a cardiac rehabilitation program for 8 weeks.InterventionsPatients were randomly assigned into 2 groups that performed either interval training (IT) or continuous training (CT). IT consisted of 3 sessions of 12 repetitions of 30 seconds of exercise at very high intensity, followed by 60 seconds of complete rest. The CT group performed CT exercises, which consisted of 45 minutes of aerobic exercise.Main Outcome MeasuresParameters of gas exchanges: peak oxygen consumption (Vo2peak), first ventilator threshold (VT1), distance at six-minute walk test (6MWT), and level of anxiety and depression were measured.ResultsThe IT group increased significantly their Vo2peak, the duration of the exercise test, the oxygen pulse, oxygen consumption at the VT1, and the distance walked during the 6MWT. The CT group only increased the time at the VT1 and the distance performed at the 6MWT. The improvement in the time at the VT1 was significantly higher for the IT group than for the CT group.ConclusionsThis study shows that IT at very high intensity for patients with heart failure appears to be more effective than CT in improving indices of submaximal exercise capacity.  相似文献   
103.
AIM: Transient small bowel stoma is usually closed 9-12 weeks after initial operation (late closure). Since these stoma have a poor physiological and psychological impact with frequent social consequences, we wanted to estimate feasibility and results of early closure of small bowel stoma. PATIENTS AND METHOD: From January 1998 to December 2001, 39 patients (21 women and 18 men, mean age: 64 years) with a transient small bowel stoma were elected for early closure. Early closure was performed only if the patient was in good condition, and without developing wound or general sepsis. In the other patients, the stoma was closed in the usually recommended delay (> 8 weeks). Fifteen patients had an early closure of their stoma in a mean delay of 10.0 +/- 0.8 days after the initial procedure. Twenty-four patients had a late closure of their stoma in a mean delay of 11.4 +/- 3.7 weeks. RESULTS: There were no postoperative deaths and no intestinal fistula. Four (10%) wound abscesses occurred and were managed without any surgical procedure, 3 in the early closure group (20%) and 1 in the late closure group (4%) (P=0.85, NS). Time to recovered bowel activity and to resumed oral feeding were equivalent in the two groups. The mean length of hospital stay was longer in the delayed group (34.5 +/- 18.6 days) than in the early group (23.1 +/- 4.6 days) (P<0.01). CONCLUSION: Early closure of bowel stoma can be performed without major complications in elective patients. This procedure shortens hospital stay.  相似文献   
104.
BCL2 mutations have been suggested to confer an adverse prognosis to follicular lymphoma (FL) patients, but their prognostic value has not been assessed in patients treated with a rituximab‐containing regimen. Here we evaluated the prognostic value of BCL2 mutations in a large prospective cohort of 252 patients with FL treated with immunochemotherapy in the PRIMA randomized trial. Using a DNA‐targeted sequencing approach, we detected amino acid altering mutations in 135 patients (54%) and showed that these mutations were probably mediated by the over‐activation of AICDA (activation‐induced cytidine deaminase) in the context of the t(14;18) translocation. The BCL2 variants identified in PRIMA patients affected the BH1, BH2, and BH3 functional motifs at a lower frequency than the N‐terminus and flexible loop domain, with mostly conservative aminoacid changes. With a median follow‐up of 6.7 years, we did not observe any impact of BCL2 mutations either on overall survival or progression‐free survival.  相似文献   
105.
Liver fibrosis (LF) must be assessed before talking treatment decisions in hepatitis B. In Burkina Faso, liver biopsy (LB) remains the “gold standard” method for this purpose. Access to treatment might be simpler if reliable alternative techniques for LF evaluation were available. The hepatitis B virus (HBV)-infected patients who underwent LB was invited to have liver stiffness measurement (Fibroscan) and serum marker assays. Fifty-nine patients were enrolled. The performance of each technique for distinguishing F0F1 from F2F3F4 was compared. The area under receiver operating characteristic (AUROC) curves was 0.61, 0.71, 0.79, 0.82, and 0.87 for the aspartate transaminase to platelet ratio index (APRI), Fib-4, Fibrotest, Fibrometre, and Fibroscan. Elastometric thresholds were identified for significant fibrosis and cirrhosis. Combined use of Fibroscan and a serum marker could avoid 80% of biopsies. This study shows that the results of alternative methods concord with those of histology in HBV-infected patients in Burkina Faso. These alternative techniques could help physicians to identify patients requiring treatment.  相似文献   
106.
A venobronchial fistula developed between the azygous vein and the upper aspect of the right main bronchus 12 months after completion of the treatment of a stage IIIB non-small-cell lung cancer in a 54-year-old man. The fistula contained the tip of the catheter placed for chemotherapy perfusion. The reported case presented risk factors previously identified for such a complication. In addition, some clinical particularities were present, suggesting new potent risk factors and some preventive means for safe long-term central venous catheterization.  相似文献   
107.
The worldwide recrudescence of tuberculosis and the widespread appearance of antibiotic resistance have strengthened the need for rapid and specific diagnostic tools. The prevailing microbiological identification of Mycobacterium tuberculosis, the causative agent of tuberculosis, which implies the use of in vitro cultures and acid-fast staining microscopy, is time-consuming. Detection of M. tuberculosis directly in clinical samples through PCR amplification of mycobacterium-specific genes, designed to shorten diagnostic delay, demonstrated reliability and high sensitivity. However, the quality of the diagnosis depends on the specificity of the target sequence for M. tuberculosis complex strains. In the present study, we demonstrated the specificity of recA and pps1 inteins for this complex and thus the feasibility of using intein-coding sequences as a new target for PCR diagnosis. Indeed, the recA and pps1 genes of 36 clinical isolates of M. tuberculosis and 10 field strains of M. bovis were found to be interrupted by an intein sequence at the RecA-a and Pps1-b sites, respectively, while a large number of nontuberculous mycobacterial species failed to demonstrate these insertions. Besides, the MtuPps1, which was cloned and expressed in Escherichia coli, was shown to possess an endonuclease activity. The intein cleaves the 40-bp sequence spanning the intein insertion site Pps1-b in the inteinless pps1 gene. In addition to the PCR amplification of recA and pps1 intein genes as a tool for diagnosis, the specific endonuclease activity could represent a new molecular approach to identify M. tuberculosis.  相似文献   
108.
Meningiomas account for approximately 30% of all primary central nervous system tumors and are found in half of neurofibromatosis type 2 patients often causing significant morbidity. Although most meningiomas are benign, 10% are classified as atypical or anaplastic, displaying aggressive clinical behavior. Biallelic inactivation of the neurofibromatosis 2 (NF2) tumor suppressor is associated with meningioma formation in all NF2 patients and 60% of sporadic meningiomas. Deletion of the p16(INK4a)/p14(ARF) locus is found in both benign and malignant meningiomas, while mutation of the p53 tumor suppressor gene is uncommon. Previously, we inactivated Nf2 in homozygous conditional knockout mice by adenoviral Cre delivery and showed that Nf2 loss in arachnoid cells is rate-limiting for meningioma formation. Here, we report that additional nullizygosity for p16(Ink4a) increases the frequency of meningioma and meningothelial proliferation in these mice without modifying the tumor grade. In addition, by using magnetic resonance imaging (MRI) to screen a large cohort of mutant mice, we were able to detect meningothelial proliferation and meningioma development opening the way to future studies in which therapeutic interventions can be tested as preclinical assessment of their potential clinical application.  相似文献   
109.
110.
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