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   294篇
  免费   17篇
儿科学   4篇
妇产科学   6篇
基础医学   18篇
口腔科学   3篇
临床医学   5篇
内科学   157篇
皮肤病学   3篇
神经病学   53篇
特种医学   3篇
外科学   24篇
综合类   3篇
预防医学   15篇
眼科学   1篇
药学   3篇
肿瘤学   13篇
  2022年   2篇
  2021年   5篇
  2020年   6篇
  2019年   4篇
  2018年   9篇
  2017年   3篇
  2016年   7篇
  2015年   5篇
  2014年   11篇
  2013年   14篇
  2012年   25篇
  2011年   15篇
  2010年   7篇
  2009年   13篇
  2008年   17篇
  2007年   16篇
  2006年   16篇
  2005年   17篇
  2004年   19篇
  2003年   17篇
  2002年   11篇
  2001年   12篇
  2000年   11篇
  1999年   11篇
  1998年   4篇
  1997年   2篇
  1994年   1篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
  1985年   5篇
  1984年   4篇
  1983年   4篇
  1982年   3篇
  1981年   1篇
  1979年   1篇
  1975年   2篇
  1972年   1篇
  1968年   1篇
  1901年   1篇
  1899年   2篇
  1879年   1篇
  1876年   1篇
排序方式: 共有311条查询结果,搜索用时 15 毫秒
1.
Introduction: Murine placentation is associated with trophoblast cells invasion of the maternal endometrium and extensive maternal and foetal angiogenesis. Both processes involve proteases‐dependent extracellular matrix remodelling. Among the protease inhibitors, plasminogen activator inhibitor‐1 (PAI‐1) is transiently produced by spongiotrophoblasts and trophoblast giant cells at days 10.5‐11.5 day post‐coitum (dpc). Although accumulating evidence demonstrates the key role of PA‐1 in pathological angiogenesis, its function during placental vascularisation remains to be elucidated. PAI‐1 knockout mice are fertile and the litter sizes are normal. We have therefore analysed the consequence of PAI‐1 deficiency on murine placentation. Material and Methods: We have studied the possible role of PAI‐1 by quantitating the placental vessel density, the relative thickness of the labyrinth, decidua and spongiotrophoblast at day 10.5, 12.5 and 14.5 dpc in mice deficient for PAI‐1 or in control mice. An original method of computer‐assisted image analysis allowed us to quantify alterations of several placental compartments identified with specific monoclonal antibodies (keratin, desmin, fibrinogen and MECA‐32). To investigate the differentially expressed genes, we performed laser capture microdissection (LCM), followed by genome‐wide expression profiling using high‐density oligonucleotides microarray analysis (GeneChip Mouse Genome 430 2.0 Array, Affymetrix). Data were analysed using Ingenuity Pathways Analysis (Ingenuity Systems®, http://www.ingenuity.com ). Results: At 10.5 and 12.5 dpc, an abnormal placental morphology was observed in both labyrinth and spongiotrophoblast layers in PAI‐1‐/‐ mice. Lack of PAI‐1 resulted in a transient decreased maternal and fetal vascularisation of the placenta that caused (1) an enhancement in the decidua/labyrinth and labyrinth/spongiotrophoblast thickness ratios, (2) a significant increase of trophoblast density. Normalization of placental morphology occurred by day 14.5 dpc in PAI‐1 deficient mice. Statistical analysis of microarrays revealed 706 genes differentially expressed between PAI‐1 deficient and normal mice in the labyrinth zone at 10.5 dpc. At 14.5 dpc, only 205 genes are differentially expressed. Using Ingenuity Pathways Analysis, most of those genes were found to be associated to lipid metabolism, cellular growth and proliferation. Conclusion: Despite a transient PAI‐1 requirement for optimal placental angiogenesis, this gene does not appear to be essential for trophoblast invasion and placentation.  相似文献   
2.
A steering committee, held by the French Food Safety Agency (AFSSA) has discussed the possibilities for flour fortification in vitamins B in France. Folic acid is known to be efficient in preventing neural tube defects (NTD) ; it also has a probable effect of preventing cardio- and cerebrovascular diseases, and has a possible effect on cancers. The published AFSSA report advocates the necessity for a public health evaluation of the benefits and risks of fortification and leads to recommend the launching of a pilot programme in the Alsace region over 5 years, with a comprehensive assessment using control regions. Depending on the results in Alsace and the availability of new data regarding this issue, it will be possible to generalise flour fortification over the country, if possibly before the end of the pilot programme.  相似文献   
3.
The predictive value of vascular biomarkers such as pulse wave velocity (PWV), central arterial pressure (CAP), and augmentation index (AIx), obtained through pulse wave analysis (PWA) in resting conditions, has been documented in a variety of patient groups and populations. This allowed to make appropriate recommendations in clinical practice guidelines of several scientific societies. Due to advances in technologies, largely operator-independent methods are currently available for estimating vascular biomarkers also in ambulatory conditions, over the 24 h. According to the acceptable accuracy and reproducibility of 24-h ambulatory PWA, it appears to be a promising tool for evaluating vascular biomarkers in daily life conditions. This approach may provide an opportunity to further improve the early cardiovascular screening in subjects at risk. However, concerning the clinical use of PWA over the 24 h in ambulatory conditions at the moment, there is no sufficient evidence to support its routine clinical use. In particular, long-term outcome studies are needed to show the predictive value of 24-h PWV, CAP, and AIx values, provided by these devices, over and beyond peripheral blood pressure, and to answer the many technical and clinical questions still open. To this regard, the VASOTENS Registry, an international observational prospective study recently started, will help providing answers on a large sample of hypertensive patients recruited worldwide.  相似文献   
4.
5.
BackgroundDysregulation of angiogenesis and lymphangiogenesis could participate in psoriasis pathogenesis. Analysis of nascent psoriasis lesions should help at identifying early vascular anomalies.ObjectiveTo analyse vascular development, angiogenesis and lymphangiogenesis markers expression in uninvolved skin in psoriatic patients (N), early psoriasis lesions or pinpoints (PP) and psoriasis plaques (PSO).MethodsSkin biopsies were taken in 17 patients in N and in PSO and/or PP. The mRNA steady-state level of angiogenesis and lymphangiogenesis markers was measured by RT-PCR. Immunohistochemistry was performed for von Willebrand factor, podoplanin, Ki-67 and VEGFR3. Blood (BV) and lymphatic (LV) vessels expansion was measured by computer-assisted morphometry.ResultsClinical and epidermal aspects indicated that PP are intermediate between N and PSO. While total BV area was already increased in PP similarly to PSO as compared to N, LV area in PP was intermediate between N and PSO. Mean LV size was identical in N and PP and increased in PSO, mean BV size in PP being intermediate between N and PSO. VEGF-A 189 variant was increased in PP as compared to N and PSO. As compared to N, angiogenesis markers (VEGF-A isoforms, PlGF, VEGFR2, NRP-1), VEGF-C and NRP-2 were similarly increased in PP and PSO. Keratin 16 and the lymphangiogenesis markers (VEGFR3, prox-1) were intermediate in PP.ConclusionThese data suggest that the expansion of lymphatic vessels occurs after blood vascular development in psoriasis. Expansion of BV in PP could be followed by vessel enlargement during progression to PSO, in parallel with a decreased VEGF-A 189/VEGF-A 121 balance in plaques.  相似文献   
6.
Necrotizing fasciitis is a rare soft tissue infection and a life-threatening emergency, often fatal. Its incidence and management are described plentifully in the medical literature regarding the most common anatomical sites involved like the abdomen, lower and upper limbs, and perineum. However, available data and case reports of chest wall necrotizing fasciitis after thoracic procedures are scarce, mainly after major cardiac operations. We report and discuss a case of necrotizing fasciitis of the chest wall occurring in the immediate postoperative period of a cardiac procedure, and include a brief review of the concepts, pathophysiology, and treatment reported in the medical literature. We emphasize the need for early diagnosis and urgent and effective surgical debridement. Of importance is the fact that we have not found any references in the literature to cases similar or equal to the one we describe here, which occurred in the postoperative period of a cardiac procedure.  相似文献   
7.

ASD symptomology and behavioral problems pose challenges for children with ASD in school. Disagreement between parents and teachers in ratings of children’s behavior problems may provide clinically relevant information. We examined parent–teacher disagreement on ratings of behavior problems among children with ASD during the fall and spring of the school year. When child, teacher, and class characteristics were considered simultaneously, only ASD symptom severity predicted informant disagreement on internalizing and externalizing behavior problems. We also examined associations between informant disagreement and parent school involvement. Cross-lagged panel analyses revealed that higher informant disagreement on children’s behavior problems in the fall predicted lower parent school involvement in the spring, suggesting that greater informant agreement may foster parental school involvement over time.

  相似文献   
8.
Cardiac angiosarcomas are malignant tumors that almost invariably have a short and fatal evolution. The therapeutic approach includes surgery, chemotherapy, and radiation therapy, alone or in combination. Heart transplantation is an attractive option in nonresectable tumors, even though the current experience is still limited. However, in most patients, the diagnosis is still established late, and survival is only slightly altered by the proposed treatments, mainly due to previously existing and undetected metastases. We report a case that illustrates the therapeutic dilemma faced with this neoplasia, and we discuss the case based on a literature review.  相似文献   
9.
Obtaining pulse pressure non-invasively from applanation tonometry requires the calibration of pressure waveform with brachial systolic and diastolic blood pressure. In the literature, several calibration methodologies are applied, and clinical studies disagree about the predictive value of central hemodynamic parameters. Our aim was to compare 4 calibration methodologies and assess the usefulness of pulse pressure amplification as an index independent of calibration. We investigated 108 subjects with tonometry in carotid, femoral, brachial, radial and dorsalis-pedis arteries; pulse pressure amplification between arterial waveforms was calculated. Four methods to calibrate the waveforms were compared: the 1/3 rule, the 40% rule, the integral of radial and brachial waveforms. Pulse pressure amplification in 5 arterial territories (carotid-femoral, carotid-brachial, carotid-radial and carotid-pedis amplifications; femoral-pedis amplification) was studied. Pulse pressure was successfully measured non-invasively at the 5 arterial sites. Pulse pressure was markedly dependent on calibration, with differences up to 18 mmHg between methods. Calculation of pulse pressure amplification eliminated effects of calibration method. Furthermore, pulse pressure amplifications in the 5 arterial sites presented a distinct pattern of clinical/biological determinants: heart rate and body height were common determinants of carotid to brachial, radial and femoral amplifications; diabetes was related to carotid to brachial amplification and pulse wave velocity to femoral to pedis amplification. In conclusion, the calibration of pulse pressure will influence results of clinical trials, but calculation of pulse pressure amplification can avoid this. We also suggest that the alteration of amplification in each arterial territory might be considered as a signal of clinical/subclinical damage.  相似文献   
10.
Observational studies have shown that some of the classic CV risk factors, namely hypertension or hypercholesterolemia, become nebulous, or even act in the reverse direction, in the oldest people. We investigated whether in the elderly, increased aortic stiffness was associated with higher mortality risk, before and after adjustments on common geriatric confounders. In a cohort of 331 (86 men) subjects aged >70 years (mean age (± s.d.): 85 ± 7 years), aortic stiffness was assessed by carotid-femoral pulse wave velocity (PWV). Classical CV risk factors were determined simultaneously, in association with inflammation and denutrition parameters. One hundred and ten subjects died during a 2-year follow-up period. In crude analysis, a positive non-significant trend was observed between PWV and mortality risk. Multivariate Cox regression analysis showed that five parameters entered the prediction model: two were positively related to mortality risk, PWV (P = 0.008) and orosomucoide (P = 0.045), and three were related negatively, total cholesterol (P = 0.006), albumin (P = 0.026) and body weight (P = 0.035). Interaction analysis revealed that the effect of PWV on mortality was increased in the presence of renal dysfunction and increased inflammation. In conclusion, although marginally significant in crude analysis, PWV is a powerful determinant of prognosis in the oldest people taking into account inflammation and denutrition.  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