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   4435篇
  免费   223篇
  国内免费   36篇
耳鼻咽喉   46篇
儿科学   53篇
妇产科学   59篇
基础医学   548篇
口腔科学   122篇
临床医学   312篇
内科学   1438篇
皮肤病学   88篇
神经病学   360篇
特种医学   101篇
外科学   614篇
综合类   23篇
一般理论   1篇
预防医学   202篇
眼科学   68篇
药学   274篇
中国医学   8篇
肿瘤学   377篇
  2023年   29篇
  2022年   58篇
  2021年   100篇
  2020年   63篇
  2019年   78篇
  2018年   111篇
  2017年   74篇
  2016年   84篇
  2015年   109篇
  2014年   163篇
  2013年   189篇
  2012年   289篇
  2011年   297篇
  2010年   175篇
  2009年   161篇
  2008年   296篇
  2007年   328篇
  2006年   287篇
  2005年   329篇
  2004年   302篇
  2003年   267篇
  2002年   218篇
  2001年   43篇
  2000年   35篇
  1999年   40篇
  1998年   39篇
  1997年   32篇
  1996年   35篇
  1995年   45篇
  1994年   32篇
  1993年   25篇
  1992年   31篇
  1991年   21篇
  1990年   21篇
  1989年   12篇
  1988年   16篇
  1987年   23篇
  1986年   13篇
  1985年   12篇
  1984年   24篇
  1983年   20篇
  1982年   19篇
  1981年   10篇
  1980年   8篇
  1979年   8篇
  1977年   11篇
  1976年   7篇
  1975年   10篇
  1974年   6篇
  1971年   7篇
排序方式: 共有4694条查询结果,搜索用时 31 毫秒
91.
The purpose of this study was to evaluate the safety and efficacy of the new Fox Hollow atherectomy device (FHT) designed for more efficient and easier plaque removal. The FHT has short rigid section and low-profile cutter mounted on a monorail catheter. The FHT catheter was utilized in 77 patients with 98 lesions. Mean reference vessel diameter was 2.75 +/- 0.51 mm. Successful atherectomy with tissue retrieval was performed in 94 lesions (96%). Following atherectomy, mean diameter stenosis was reduced from 71.1% to 31.9% and further to 10.4% following adjunctive treatment. Angiographic complications were one coronary perforation and one adventitial staining, both successfully treated with prolong balloon inflation and stent implantation. Nine patients (11.7%) had in-hospital non-Q-wave myocardial infarction (MI). One patient died (1.3%) for noncardiac reasons and one had MI (1.3%) at 6-month follow-up. Target lesion revascularization was required in 13 (13.8%) lesions and target vessel revascularization in 15 (20.3%) patients. There was target vessel failure in 17 (23.0%) patients. Plaque debulking with the FHT catheter can be performed safely and effectively in relatively small vessels and complex lesions located in mid-distal artery segments with 6-month clinical outcome similar to prior atherectomy devices.  相似文献   
92.
OBJECTIVES: The aim of the study was the assessment of the clinical, angiographic and procedural characteristics correlated with freedom from adverse events at 1 year in a real life setting of consecutive bifurcation lesions. BACKGROUND: Even if stent implantation has shown to be superior to conventional balloon angioplasty in most coronary lesions, bifurcation treatment with stent implantation both in main and in side branch (SB) still raises controversy. METHODS: We reviewed the results obtained in a prospective multicenter registry of 150 patients with 158 bifurcation lesions involving a SB of sufficient diameter to be treated, if necessary, with a polymer based paclitaxel eluting stent (PES, TAXUS). Two stents were used in 118 lesions (74.7%). Final kissing balloon inflation was performed in 87/118 lesions (73.7%) and in 30/40 lesions (75.0%) of the 2 and 1 stent group respectively. RESULTS: At 1-year clinical follow-up we observed 4 stent thromboses, all involving the SBs of the 2 stents group (2.7%). Unlike previous reports, revascularization involved the main vessel in the majority of patients (21/150, 14.0%). After an exploratory multivariable analysis the only parameter predictive of target lesion revascularization (TLR) (HR 0.52; CI 95% 0.11-0.86; p = 0.02) and target vessel revascularization (TVR) (HR 0.47; CI 95% 0.14-0.90; p = 0.03) was postprocedural main branch minimal lumen diameter (MB-MLD). CONCLUSIONS: In a real life setting of consecutive bifurcation lesions, thrombosis rate, concentrated in the SB and the 2-stents group, and need for target lesion revascularization remain higher than in less complex lesion subgroups treated with PES. No differences in immediate success and TLR were observed between 2 stents and 1 stent groups. The frequently observed suboptimal stent expansion and final MB-MLD predict 1 year revascularization.  相似文献   
93.
OBJECTIVE: Hemodynamic measurements are important in the understanding of hemodialysis (HD) hypertension and intradialytic hypotension. The reproducibility of hemodynamic measurements in HD patients is not known and is the objective of this report. METHODS: We enrolled 13 male patients (mean age 63+/-13 years) on stable chronic HD. Blood pressure (BP) and hemodynamic variables were obtained with a pulse dynamic technology device. Measurements were taken before and after HD, in the supine and standing positions over a 2-week period. RESULTS: Ranges for the average intraindividual standard deviation for each hemodynamic variable before and after HD in both supine and standing positions were: 8.3-14.5 mmHg for oscillometric systolic BP; 4.1-10.7 mmHg for oscillometric diastolic BP; 10.7-14.5 mmHg for manual systolic BP; 5.4-8.8 mmHg for manual diastolic BP; 131.4-188.9 mmHg/s for left ventricular dP/dtmax; 0.17-0.27 L/min/m for cardiac index; 142.4-222.6 dynes/s/cm for systemic vascular resistance; 0.59-1.13%/mmHg for brachial artery distensibility; and 0.09-0.15 ml/mmHg for systemic vascular compliance. Repeated measures analysis of variance results showed no significant variability in measures. Intraclass correlation coefficient ranges were 0.58-0.72 for oscillometric systolic BP, 0.46-0.83 for oscillometric diastolic BP, 0.41-0.62 for manual systolic BP, 0.57-0.84 for manual diastolic BP, 0.10-0.78 for left ventricular dP/dtmax, 0.63-0.84 for cardiac index, 0.47-0.80 for systemic vascular resistance, 0.40-0.84 for brachial artery distensibility, and 0.62-0.88 for systemic vascular compliance. No correlation was observed between interdialytic weight gain and hemodynamic variability. CONCLUSION: In this pilot study, hemodynamic variables have acceptable reproducibility in chronic stable HD patients. Our results are relevant to the use of hemodynamic monitoring in HD practice and research.  相似文献   
94.
Peripheral arterial disease (PAD) is a predictor of cardiovascular risk. However, it is unknown whether PAD severity influences inflammatory status and endothelial function, which play a major role in atherosclerosis. Accordingly, we measured brachial artery flow-mediated dilation (FMD), and plasma levels of several inflammatory markers in 15 control subjects, and 19 asymptomatic and 19 symptomatic PAD patients. Each symptomatic patient was matched to an asymptomatic patient for age, sex, risk factors, presence of cardiovascular disease, and pharmacological treatments. Asymptomatic patients had similar inflammatory profiles as controls, but lower median FMD (11.7% vs 8.5%, p < 0.01). Compared with asymptomatic patients, symptomatic patients had higher median C-reactive protein (1.5 mg/l vs 6.0 mg/l, p < 0.05) and interleukine-6 (1.5 pg/ml vs 3.5 pg/ml, p < 0.05), and lower FMD (8.5% vs 5.1%, p < 0.01). In the 38 PAD patients, the ankle/brachial pressure index correlated positively with FMD (p < 0.01), and negatively with C-reactive protein (p < 0.05), soluble intercellular adhesion molecule-1 (p < 0.05) and soluble vascular cell adhesion molecule-1 (p < 0.05). Thus, in PAD, endothelial function and inflammatory status are related to the severity of the circulatory impairment. This finding may contribute to the explanation of the increasingly poor prognosis with increased PAD severity.  相似文献   
95.
As biocompatible matrices, porcine dermal scaffolds have limited application in tissue engineering due to rapid degradation following implantation. This study compared the physical, chemical and biomechanical changes that occurred when genipin and quercetin were used to crosslink dermal scaffolds and to determine whether quercetin could be used as an alternative to genipin. Physicochemical changes in the collagen were assessed using spectroscopic methods [X‐ray diffraction analysis (XRD) and nuclear magnetic resonance (NMR) analysis]. The crosslinking reaction was evaluated by quantification of amino acids and the degree of this reaction by ninhydrin assay. Because the mechanical behaviour of the collagen matrices is highly influenced by crosslinking, the tensile strength of both sets of scaffolds was evaluated. The highest mechanical strength, stiffness, degree of crosslinking and changes in the packing features of collagen (measured by XRD) were achieved using genipin. Some of the results found in the quercetin‐crosslinked scaffolds were possibly due to hydration and dehydration effects elicited by the solvents (phosphate‐buffered saline or ethanol), as seen in the NMR results. In the quercetin‐ethanol‐crosslinked scaffolds, possible reorientation of the amino groups of the collagen molecule may have taken place. Therefore, depending on their proximity to the crosslinking reagent, different types and numbers of interactions may have occurred, inducing a higher crosslinking degree (as evidenced by the ninhydrin assay) and reduction in the free amino acids after reaction. Both crosslinking agents and solvents interfere in the physicochemical properties of collagen thereby inducing variations in the matrix structure. Quercetin‐crosslinked scaffolds may have broader clinical application where a lower degree of crosslinking and stiffness is required. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
96.
The long-term changes of liver stiffness (LS) in patients who achieve viral clearance after direct-acting anti-HCV therapy remain undefined. We conducted a multicentre prospective study to investigate this aspect. Patients with HCV infection treated with DAAs were enrolled from six Italian centres; they underwent clinical, biochemical, ultrasound and transient elastography evaluations before treatment (T0), 12 weeks (SVR12) and 24 months (T24) after the end of therapy. Among the 516 consecutive patients enrolled, 301 had cirrhosis. LS significantly decreased from T0 to SVR (14.3 vs 11.1 kPa, p = .002), with a progressive reduction until T24 (8.7 kPa, p < .001). However, only patients with steatosis and those who developed HCC did not experience a late improvement in LS. Multivariate analysis of baseline and follow-up variables identified steatosis as the only independent predictor of failure of LS improvement (OR 1.802, p = .013). ROC curve analysis of the association of LS with the risk of developing HCC showed that SVR12 ≥14.0 kPa had the highest accuracy (sensitivity 82%, specificity 99%; AUC: 0.774). Multivariate analysis revealed that LS was the only variable independently associated with an increased risk of developing HCC (OR 6.470, p = .035). Achieving an SVR was associated with a progressive, long-term decline of LS, suggesting a late improvement in liver fibrosis, besides the resolution of inflammation. Fatty liver and the development of HCC interfered with late reduction of LS. Patients with an LS ≥14 kPa at 12 weeks after the end of treatment were at higher risk for developing HCC.  相似文献   
97.
Over the past 10 years recombinant activated factor VIIa (rFVIIa) has been successfully used for treatment and prophylaxis of bleeding in patients with platelet defects, including thrombocytopenia and congenital and acquired platelet function abnormalities. Most reported data concern patients with Glanzmann's thrombasthenia and the information available is still limited, especially for surgery. We report on a 15-year-old girl with thrombocytopenia ( approximately 60,000/microl) and platelet dysfunction (bleeding time 30 min, absent platelet aggregation and ATP secretion in response to collagen), related to thrombocytopenia with absent radii syndrome, undergoing two surgical interventions on the upper limbs due to forearm deformities, with prolonged postoperative revisions. In both surgeries rFVIIa was successfully employed as a bolus administration (80 microg/kg every 4 h during the first day, then every 6 h over the following 5 and 3 days, respectively; tranexamic acid was associated from the second day, administered for 2 weeks), avoiding the need for blood products. This report highlights rFVIIa as an attractive, alternative approach to secure hemostasis in patients with platelet defects; on the other hand, the heterogeneity of reported rFVIIa treatment regimens and, in particular, the lack of definite and easily available parameters (or assays) for monitoring rFVIIa efficacy and safety are the main open issues in this setting.  相似文献   
98.
Surveys of prescribing patterns in both hospitals and primary care have usually shown delays in translating the evidence from clinical trials of pharmacological agents into clinical practice, thereby denying patients with heart failure (HF) the benefits of drug treatments proven to improve well-being and prolong life. This may be due to unfamiliarity with the evidence-base for these therapies, the clinical guidelines recommending the use of these treatments or both, as well as concerns regarding adverse events. ACE inhibitors have long been the cornerstone of therapy for systolic HF irrespective of aetiology. Recent trials have now shown that treatment with beta-blockers, aldosterone antagonists and angiotensin receptor blockers also leads to substantial improvements in outcome. In order to accelerate the safe uptake of these treatments and to ensure that all eligible patients receive the most appropriate medications, a clear and concise set of clinical recommendations has been prepared by a group of clinicians with practical expertise in the management of HF. The objective of these recommendations is to provide practical guidance for non-specialists, in order to increase the use of evidenced based therapy for HF. These practical recommendations are meant to serve as a supplement to, rather than replacement of, existing HF guidelines.  相似文献   
99.
Calcification of the mitral annulus is a common echocardiographic finding in the elderly, particularly in females. Calcium deposits are generally located in the posterior mitral ring, sometimes extending to the whole mitral annulus and involving the mitral valve apparatus. The present report refers to 2 patients with a very atypical mass-like calcification of the mitral annulus resembling a cardiac tumor. A detailed evaluation of the mass was obtained at transthoracic and transesophageal echocardiography; the differential diagnosis with other intracardiac masses was aided by the use of computed tomography and magnetic resonance imaging. To our knowledge there has been no prior report of such a lesion evaluated at cardiac magnetic resonance imaging.  相似文献   
100.
Alpha-2a-interferon (IFN) has demonstrable activity in advance and refractory multiple myeloma (MM), because of the in vitro synergism between IFNs and cytotoxic agents we report the preliminary results of a therapeutic trial of 50 patients with MM. Twenty-eight patients were randomized to receive melphalan plus prednisone (MP) and 22 were randomized to receive IFN plus MP (IFN-MP). Criteria for response, progression and relapse were those of the Southwestern Oncology Group. 95% of the patients receiving IFN-MP responded to therapy as opposed to 68% of the patients receiving MP (P less than 0.05). Response was independent of M-component immunoglobulin class but in stage III it was higher in the IFN-MP group than in the MP group (P less than 0.05). The combination IFN-MP was well tolerated without unusual or unexpected toxic effects. The response duration time was longer in the IFN-MP group than in the MP group (P less than 0.025). The median survival was 80 weeks in the MP group and in the IFN-MP group the 93% of patients were still alive after 90 weeks (P less than 0.025). Our results show that the use of the IFN as an adjuvant to MP improves the percentage of responders, the response duration time and the median survival of untreated patients with MM.  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