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   686篇
  免费   72篇
  国内免费   4篇
耳鼻咽喉   8篇
儿科学   9篇
妇产科学   20篇
基础医学   101篇
口腔科学   19篇
临床医学   56篇
内科学   238篇
皮肤病学   7篇
神经病学   34篇
特种医学   17篇
外科学   108篇
综合类   5篇
预防医学   30篇
眼科学   11篇
药学   38篇
肿瘤学   61篇
  2023年   5篇
  2022年   5篇
  2021年   7篇
  2020年   9篇
  2019年   13篇
  2018年   16篇
  2017年   5篇
  2016年   8篇
  2015年   21篇
  2014年   16篇
  2013年   24篇
  2012年   46篇
  2011年   39篇
  2010年   22篇
  2009年   22篇
  2008年   33篇
  2007年   40篇
  2006年   52篇
  2005年   42篇
  2004年   39篇
  2003年   45篇
  2002年   30篇
  2001年   14篇
  2000年   14篇
  1999年   14篇
  1998年   12篇
  1997年   12篇
  1996年   11篇
  1995年   8篇
  1994年   9篇
  1993年   11篇
  1992年   7篇
  1991年   13篇
  1990年   14篇
  1989年   9篇
  1988年   9篇
  1987年   5篇
  1986年   16篇
  1985年   8篇
  1984年   4篇
  1983年   2篇
  1982年   5篇
  1981年   5篇
  1980年   3篇
  1979年   3篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1968年   2篇
  1956年   1篇
排序方式: 共有762条查询结果,搜索用时 15 毫秒
91.
Superficial vein thrombosis (SVT) risk factors are close to those of venous thromboembolism (VTE). Diagnosis is made in a clinical setting but ultrasonography is useful to eliminate concomitant deep vein thrombosis (DVT). For SVT of the lower limbs, which is the main location, varicose veins represent the principal cause but underlying conditions (e.g.: autoimmune diseases, malignancy or thrombophilia) must be sought in idiopathic, migrant or recurrent SVT and in the absence of varicose veins. Concomitant DVT and pulmonary embolism can occur in approximately 15% and 5% respectively. Historical treatments consist of anti-inflammatory agents plus elastic stockings and, in case of varicose veins, thrombectomy and stripping. Other treatments (anticoagulants, vein ligation) were assessed to limit the VTE risk. A one-month prophylactic dose of low molecular weight heparin plus elastic stockings could be the appropriate strategy in most cases. Other studies are needed before definitive conclusions can be drawn.  相似文献   
92.
Deformation analysis using 2-dimensional strain echocardiography can detect early systolic function abnormalities in patients with left ventricular hypertrophy. This study was designed to characterize global and regional myocardial deformation using 2-dimensional strain in professional soccer players (PSPs) compared with control subjects and patients with hypertrophic cardiomyopathy (HC). Twenty nine PSPs, 26 patients with HC, and 17 controls were investigated at rest using transthoracic echocardiography with 2-dimensional strain analysis. Radial and transverse strains were significantly higher in PSPs compared with controls, whereas longitudinal strain was lower. Compared with patients with HC, athletes had higher values for transverse, radial, and circumferential strains. In pathologic hypertrophic segments, longitudinal strain was lower in patients with HC than in PSPs. In conclusion, 2-dimensional strain can identify specific patterns of myocardial deformation in PSPs, controls, and patients with HC. It has the potential to become a routinely used method for the differentiation of athlete's heart and HC.  相似文献   
93.
Whilst autologous stem cell transplantation (auto‐SCT) is considered standard of care for relapsed/refractory classical Hodgkin lymphoma, the role of auto‐SCT in nodular lymphocyte‐predominant Hodgkin lymphoma (NLPHL) is not well defined due to limited data. We report the first study on auto‐SCT for NLPHL with a larger cohort. Eligible for this retrospective registry study were patients reported to the EBMT between 2003 and 2013, aged 18 or older with relapsed/refractory NLPHL who underwent first auto‐SCT with disease chemosensitive to salvage therapy. NLPHL transformed to diffuse large B cell lymphoma were excluded. Sixty patients (83% male; median age 40 years) met the eligibility criteria. The median time between diagnosis and transplant was 21 months (IQR 13–58), and the median number of prior treatment lines was 2 (range 1–5), including rituximab in 63% of the patients. At auto‐SCT, 62% of the patients were in complete remission (CR) and 38% in partial remission. Seventy‐two percent of the patients received BEAM as high‐dose therapy. With a median follow‐up of 56 months (range 3–105), 5‐year progression‐free and overall survival (OS) were 66% and 87%, respectively. Univariate comparisons considering age, time from diagnosis to transplant, prior chemotherapy lines, and prior rituximab use failed to identify significant predictors for any survival endpoint except for being in CR at the time of auto‐SCT (vs PR, P = .049) for OS. Auto‐SCT in patients with relapsed/refractory NLPHL who are sensitive to salvage therapy gives excellent disease control and long‐term survival independent of the time interval between diagnosis and transplant.  相似文献   
94.

Objectives

This study sought to describe the current practices and compare outcomes according to the use of balloon aortic valvuloplasty (BAV) or not during transcatheter aortic valve replacement (TAVR).

Background

Since its development, aortic valve pre-dilatation has been an essential step of TAVR procedures. However, the feasibility of TAVR without systematic BAV has been described.

Methods

TAVR performed in 48 centers across France between January 2013 and December 2015 were prospectively included in the FRANCE TAVI (Registry of Aortic Valve Bioprostheses Established by Catheter) registry. We compared outcomes according to BAV during the TAVR procedure.

Results

A total of 5,784 patients have been included in our analysis, corresponding to 2,579 (44.6%) with BAV avoidance and 3,205 (55.4%) patients with BAV performed. We observed a progressive decline in the use of BAV over time (78% of procedures in 2013 and 49% in the last trimester of 2015). Avoidance of BAV was associated with similar device implantation success (97.3% vs. 97.6%; p = 0.40). TAVR procedures without BAV were quicker (fluoroscopy 17.2 ± 9.1 vs. 18.5 ± 8.8 min; p < 0.01) and used lower amounts of contrast (131.5 ± 61.6 vs. 141.6 ± 61.5; p < 0.01) and radiation (608.9 ± 576.3 vs. 667.0 ± 631.3; p < 0.01). The rates of moderate to severe aortic regurgitation were lower with avoidance of BAV (8.3% vs. 12.2%; p < 0.01) and tamponade rates (1.5% vs. 2.3%; p = 0.04).

Conclusions

We confirmed that TAVR without BAV is frequently performed in France with good procedural results. This procedure is associated with procedural simplification and lower rates of residual aortic regurgitation.  相似文献   
95.
96.
Urotensin II (UII) is a cyclic peptide initially isolated from the caudal neurosecretory system of teleost fish. Subsequently, UII has been characterized from a frog brain extract, indicating that a gene encoding a UII precursor is also present in the genome of a tetrapod. Here, we report the characterization of the cDNAs encoding frog and human UII precursors and the localization of the corresponding mRNAs. In both frog and human, the UII sequence is located at the C-terminal position of the precursor. Human UII is composed of only 11 amino acid residues, while fish and frog UII possess 12 and 13 amino acid residues, respectively. The cyclic region of UII, which is responsible for the biological activity of the peptide, has been fully conserved from fish to human. Northern blot and dot blot analysis revealed that UII precursor mRNAs are found predominantly in the frog and human spinal cord. In situ hybridization studies showed that the UII precursor gene is actively expressed in motoneurons. The present study demonstrates that UII, which has long been regarded as a peptide exclusively produced by the urophysis of teleost fish, is actually present in the brain of amphibians and mammals. The fact that evolutionary pressure has acted to conserve fully the biologically active sequence of UII suggests that the peptide may exert important physiological functions in humans.  相似文献   
97.
There has been growing interest in Europe in recent years in the establishment and spread of invasive mosquitoes, notably the incursion of Aedes albopictus through the international trade in used tires and lucky bamboo, with onward spread within Europe through ground transport. More recently, five other non-European aedine mosquito species have been found in Europe, and in some cases populations have established locally and are spreading. Concerns have been raised about the involvement of these mosquito species in transmission cycles of pathogens of public health importance, and these concerns were borne out following the outbreak of chikungunya fever in Italy in 2007, and subsequent autochthonous cases of dengue fever in France and Croatia in 2010. This article reviews current understanding of all exotic (five introduced invasive and one intercepted) aedine species in Europe, highlighting the known import pathways, biotic and abiotic constraints for establishment, control strategies, and public health significance, and encourages Europe-wide surveillance for invasive mosquitoes.  相似文献   
98.
Primary pulmonary hypertension and fenfluramine use.   总被引:6,自引:1,他引:6       下载免费PDF全文
Not all the risk factors for primary pulmonary hypertension (PPH) are known. Appetite suppressants, including fenfluramine derivatives, are strongly suspected aetiological agents. In a 5 year retrospective study fenfluramine use was evaluated among patients referred to a medical centre specialising in the management of PPH. Fifteen (20%) of 73 patients with PPH had used fenfluramine: all of them were women and in 10 (67%) there was a close temporal relation between fenfluramine use and the development of exertional dyspnoea. Initial right heart catheterisation in the 15 women showed severe resting pulmonary hypertension (mean (SD)) with pulmonary artery pressure (PAP) 57 (9) mm Hg, cardiac index 2.1 (0.5) l/min/m2, and pulmonary vascular resistance (PVR) 29 (10) U/m2. Short-term epoprostenol infusion produced a significant vasodilator response in 10 patients (mean fall in PVR 24 (15%) compared with control values). Three fenfluramine users with PPH showed spontaneous clinical and haemodynamic improvement 3, 6 and 12 months after drug withdrawal but there was no significant difference in overall survival (transplant recipients excluded) between fenfluramine users and controls. Histological examination of lung tissue from five women who had used fenfluramine and 22 controls, with PPH showed features typical of advanced plexogenic pulmonary arteriopathy in all. These results do not accord with earlier reports that PPH associated with fenfluramine is less severe and has a better outcome. Fenfluramine may be one aetiological agent that can precipitate or hasten the development of PPH. The results of a European case-control study should give new insights into risk factors for PPH and the cause and effect relation with fenfluramine.  相似文献   
99.
Abstract. Red blood cells (RBC) were collected with citrate-phosphate-dextrose (CPD) in a blood-pack optimal additive system. After concentration to 90% hematocrit they were diluted with saline-adenine-glucose medium (SAG-RBC), and stored for 35 days. In this work the RBC were stored in the presence of leukocytes. The SAG medium allows RBC conservation during 35 days at +4°C. The adenosine triphosphate (ATP) level of RBC is compatible with their survival. During the first 2 weeks, hemolysis of SAG-RBC was not greater than in CPD blood. Nevertheless, hemolysis reached 1.49% on day 35, and there was a marked increase in RBC osmotic fragility. Scanning electron-microscopic studies of 35-day RBC showed that the majority of them became echinocytes. After incubation in fresh frozen plasma, the RBC recovered satisfactory osmotic resistance and normal disc shape. The post-transfusion viability was normal with >70% recovery after 48 h. The in vivo restoration of 2,3-diphosphoglycerate (2,3-DPG) was rapid in the transfused SAG-RBC, 50% of the initial 2,3-DPG level being restored in 1 h. The in vivo studies proved that the functional quality of these RBC was compatible with their use in transfusion. The most important problem concerns the supernatant hemoglobin level of the SAG-RBC to be used for massive transfusion.  相似文献   
100.
The role of the SDF-1alpha chemokine-CXCR4 receptor system on tumor cell transendothelial migration was studied by culturing metastatic breast tumor cell lines, MDA-MB-231 and MDA-MB-435, either alone or on a HUVEC monolayer pre-established on a "Transwell" filter. After a 24-hour culture in the presence or absence of SDF-1alpha, tumor cell transmigration rates were compared. We showed that: CXCR4 is present on both cell lines; MDA-MB-231 but not MDA-MB-435 cell migration is stimulated by increasing concentrations of SDF-1alpha; neutralizing anti-CXCR4 antibody inhibits the SDF-1alpha chemoattractant effect; CXCR4 expression, measured by cytofluorometry, was enhanced after treatment with SDF-1alpha on MDA-MB-231 cells but remained unchanged on MDA-MB-435 cells; Scatchard analysis evidences 8.10(5) and 2.10(5) high affinity sites (KD range: 20 to 30 nM) on, respectively, MDA-MB-231 and MDA-MB-435 cells. These significant differences could explain the distinctive transendothelial migration responses of these two cell lines in the presence of SDF-1alpha.  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