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   713篇
  免费   47篇
  国内免费   3篇
耳鼻咽喉   21篇
儿科学   15篇
妇产科学   8篇
基础医学   67篇
口腔科学   21篇
临床医学   50篇
内科学   283篇
皮肤病学   2篇
神经病学   25篇
特种医学   31篇
外科学   95篇
综合类   2篇
预防医学   45篇
眼科学   14篇
药学   22篇
肿瘤学   62篇
  2024年   1篇
  2023年   4篇
  2022年   11篇
  2021年   23篇
  2020年   21篇
  2019年   15篇
  2018年   17篇
  2017年   13篇
  2016年   25篇
  2015年   10篇
  2014年   31篇
  2013年   32篇
  2012年   61篇
  2011年   67篇
  2010年   36篇
  2009年   41篇
  2008年   25篇
  2007年   47篇
  2006年   41篇
  2005年   27篇
  2004年   24篇
  2003年   34篇
  2002年   25篇
  2001年   16篇
  2000年   12篇
  1999年   9篇
  1998年   3篇
  1997年   8篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1993年   4篇
  1992年   5篇
  1991年   4篇
  1990年   9篇
  1989年   4篇
  1988年   6篇
  1987年   6篇
  1986年   8篇
  1985年   10篇
  1984年   8篇
  1983年   2篇
  1982年   3篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
  1974年   3篇
  1973年   1篇
  1972年   2篇
排序方式: 共有763条查询结果,搜索用时 15 毫秒
91.
BACKGROUND: Lymphangioleiomyomatosis (LAM), a multisystem disease occurring primarily in women, is characterized by cystic lung destruction, and kidney and lymphatic tumors, caused by the proliferation of abnormal-appearing cells (ie, LAM cells) with a smooth muscle cell phenotype that express melanoma antigens and are capable of metastasizing. Estrogen receptors are present in LAM cells, and this finding, along with reports of disease progression during pregnancy or following exogenous estrogen administration, suggest the involvement of estrogens in the pathogenesis of LAM. Consequently, antiestrogen therapies have been employed in treatment. The goal of this prospective study was to evaluate the efficacy of triptorelin, a gonadotrophin-releasing hormone analogue, in 11 premenopausal women with LAM. METHODS: Patients were evaluated at baseline and every 3 to 6 months thereafter, for a total of 36 months. Hormonal assays, pulmonary function tests, 6-min walk tests, high-resolution CT scans of the chest, and bone mineral density studies were performed. RESULTS: Gonadal suppression was achieved in all patients. Overall, a significant decline in lung function was observed; two patients underwent lung transplantation 1 year after study enrollment, and another patient was lost to follow-up. Treatment with triptorelin was associated with a decline in bone mineral density. CONCLUSIONS: Triptorelin appears not to prevent a decline in lung function in patients with LAM. Its use, however, may be associated with the loss of bone mineral density.  相似文献   
92.
Purpose  Some patients, having undergone sphincter-saving operations for rectal cancer, may suffer from fecal incontinence. This study was designed to evaluate the results of rehabilitative treatment in patients with fecal incontinence after sphincter-saving operations and to identify the negative factors that influence therapeutic success. Methods  Between January 2000 and June 2007, 88 incontinent patients (54 women; age range, 47–73 years; 69 had received a low anterior rectal resection; 19 a straight coloanal anastomosis) were included in the study. After a preliminary clinical evaluation, including the Wexner Incontinence Scale score, anorectal manometry was performed. All 88 patients underwent rehabilitative treatment according to the “multimodal rehabilitative program” for fecal incontinence. At the end of program, all 88 patients were reassessed by means of a clinical evaluation and anorectal manometry; their results were compared with the clinical and manometric data from ten healthy control subjects. Postrehabilitative Wexner Incontinence Scale scores were used for an arbitrary schedule of patients divided into three classes: Class I, good (score ≤3); Class II, fair (score >3 to ≤6); Class III, poor (score >6). Results  After rehabilitation, there was a significant improvement in the overall mean Wexner Incontinence Scale score (P < 0.03) for both surgical operation types (low anterior rectal resection: P < 0.05; coloanal anastomosis: P < 0.02). Only 21 patients (23.8 percent) were symptom-free, and 37 (42 percent) were considered Class III. A significant postrehabilitative direct correlation was found between: 1) Wexner Incontinence Scale score and degree of genital relaxation (rρ s 0.78; P < 0.001); 2) Wexner Incontinence Scale score and irradiation (rρ s 0.72; P < 0.01); and 3) Wexner Incontinence Scale score and pelvic (rρ s 0.65; P < 0.01) or anal surgery (rρ s 0.68; P < 0.01). No significant differences were found between prerehabilitative and postrehabilitative anal pressures in low anterior rectal resection and coloanal anastomosis patients. Conclusions  After rehabilitation, some patients become symptom-free, many patients show an improvement in the Wexner Incontinence Scale score, and others exhibit the highest grades of fecal incontinence. Genital relaxation, radiotherapy, and previous pelvic, and/or anal surgery are impeding factors to rehabilitative success.  相似文献   
93.
The relation of exercise-induced left ventricular (LV) outflow tract obstruction to functional capacity in hypertrophic cardiomyopathy (HC) is incompletely defined. Thus, we assessed the patterns of onset of physiologically provoked LV outflow gradients and exercise performance in 74 consecutive patients with HC (age 45 ± 16 years; 74% men) without LV outflow obstruction at rest. The subaortic gradients were measured serially using echocardiography in these 74 patients during maximum, symptom-limited, upright bicycle exercise testing. The time course of the provoked gradients and the relation to exercise performance were assessed. Of the 74 patients, 30 (41%) developed a dynamic LV outflow gradient of ≥30 mm Hg (mean 78 ± 37 mm Hg) during upright exercise testing that correlated highly with the gradients measured with the patients supine during the immediate recovery period (R2 = 0.97). The 16 patients in whom outflow obstruction developed rapidly at low exercise levels (≤5 METs) had a significantly reduced exercise capacity (6.1 ± 1.3 vs 8.0 ± 1.6 METs; p <0.01) compared to the other 14 patients in whom obstruction appeared later at greater exercise levels of >5 METs. The timing of the gradient onset was not predictable from the baseline clinical and echocardiographic features, peak exercise LV outflow tract gradient, or symptoms. In conclusion, in patients with HC without outflow obstruction at rest, the earlier onset of LV outflow tract gradients during physiologic exercise was associated with impaired exercise performance. These findings have provided insights into the determinants of functional impairment in HC and support the potential value of exercise echocardiography in the clinical assessment of patients with HC.  相似文献   
94.

Background:

Diabetes mellitus (DM) represents by itself a major risk factor for cardiovascular events and the coexistence of obesity with consequent left ventricular volumetric overload could be responsible for further damages on left ventricular function. Aim of this study was to demonstrate the effect of body mass index (BMI) on left ventricular function in diabetes patients with no cardiovascular complications and with normal ejection fraction (EF).

Materials and Methods:

We evaluated 71 stable asymptomatic diabetes patients in optimal medical treatment and 24 healthy controls (C) (45% females; mean age: 58.4 +/− 9.4 years; BMI: 23.5 +/− 1.5). We stratified diabetes patients into two groups according to BMI: BMI <30 kg/m2 (A: 44 patients; 47% females; mean age: 60.9 +/− 6.6 years; BMI: 25.7 +/− 1.9; Diabetes duration: 9.1 +/− 9.5 years); BMI >30 kg/m2 (B: 27 patients; 37% females; mean age: 56.2 +/− 7.8 years; BMI: 33.0 +/− 2.1; Diabetes duration: 8.5 +/− 5.2 years). The following parameters were evaluated by conventional two dimensional (2D) echocardiography (GE VIVID 7) and tissue Doppler imaging (TDI): left ventricular dimensions (LVIDd; PWTd; IVSd), Left Ventricular Volumes (EDV, ESV), EF (by biplane Simpson’s method), Left Ventricular Mass (by ASE formula), peak mitral annular velocity at septal and lateral levels (Sm and Sl). Global longitudinal strain (GLS) was obtained off line by Speckle tracking imaging method using Echopac 10 software.

Results:

Groups A, B were comparable for diabetes duration and glycated hemoglobin level, history of hypertension, and lipid profile. The EF was similar in the three groups, (A: 64 +/− 6%; B: 63 +/− 4%; C: 61 +/−5%; P= NS). LVMass2.7 indexed for height was significantly higher in A and B in comparison with C (A: 45.2 +/− 8.1 g/m2.7; B: 46.1 +/− 9.6 g/m2.7; C: 39.5 +/− 4.9 g/m2.7; P < 0.05). The stroke volume index (SVi) was significantly lower in B vs A (B: 35.3 +/− 5.7 ml/m2; A: 39.3 +/7.1 ml/m2; P = 0.033). GLS was significantly lower in group B respect A and C (C: 20.9 +/− 1.3%; A: -20.3+/−2.6%; B: -19 +/− 2; P < 0.05; P < 0.01).

Conclusions:

In uncomplicated asymptomatic DM patients, the presence of first degree obesity plays an incremental role in adversely affecting left ventricular function and remodeling. The conventional echocardiographic methods such as the EF and the TDI are not so sensitive to identify the early LV dysfunction such as the evaluation of GLS by Speckle Tracking echocardiography. The longitudinal subendocardial fibers dysfunction in diabetes/obese patients could be derived by the complex interaction between metabolic (diabetes) and hemodynamic/endocrine abnormalities.  相似文献   
95.
Atrial fibrillation(AF)is the most common sustained arrhythmia in patients with hypertrophic cardiomyopathy(HCM),and represents an important complication in the clinical COUlee of the disease,with adverse consequences on functional status and outcome.Studies on community-based HCM patient populations have shown that AF is associated with long-term clinical deterioration,cardioembolic stroke and increaeed cardiovascular mortality due to heart failure and stroke.Moreover.acute onset of AF may cause severe hemodynamic impairment and represent a trigger of potentially lethal ventricular arrhythmias.However,the consequences of AF on the long-term prognosis of HCM patients are not uniformly unfavorable,and may be compatible with an uneventful course,when properly managed.Management of AF in HCM is challenging,particularly when onset occurs at a young age.Both paroxysmal and permanent AF represent clear indications for oral anticoagulation.In moat patients,maintenance of sinus rhythm is highly desirable but made difficult by the limited long-term efficacy and potentially hazardous side effects of available pharmacological options.In selected patients with HCM and severely symptomatic AF,radiofrequency catheter ablation may represent an effective therapeutic ahemative,improving functional status,and reducing or postponing the need for antiarrhythmic drugs. In patients with persistent AF,in whom maintenance of sinus rhythm is not feasible.adequate ventricular rate control should be pursued aggressively by atrio-ventricular node blocking agents.  相似文献   
96.
Objective  Data on trabecular bone mass in acromegaly are controversial. All the studies are cross-sectional and bone mineral density (BMD) has been evaluated largely by dual X-ray absorptiometry (DXA), which is influenced by bone enlargement. In this study we assessed in acromegalic patients the effects overtime of GH excess on trabecular bone mass measured by single-energy quantitative computed tomography (QCT) which is not influenced by bone size.
Design  Longitudinal retrospective study.
Patients  A total of 46 acromegalic patients followed-up for 48 months (median), subdivided into four groups: group A (eugonadal patients with active disease: n  = 13), group B (hypogonadal patients with active disease; n  = 9), group C (eugonadal patients with controlled disease; n  = 10), group D (hypogonadal patients with controlled disease; n  = 14).
Measurements  Serum GH and IGF-I levels, spinal trabecular BMD, and vertebral fractures were evaluated in all patients. BMD variations were reported as change (Δ) in Z -values (Z-QCT) measured at baseline and end of follow-up per year (Δ Z-QCT).
Results  Δ Z-QCT was greater in group A vs. group B and D ( P = 0·002 and P  = 0·0001, respectively) and in group C vs. group D ( P = 0·009). Multivariate regression analysis showed that hypogonadal status (β = –0·69; P  = 0·001) and baseline duration of hypogonadism (β = 0·44; P  = 0·02) but not baseline duration of acromegaly, length of follow-up and disease activity, were significantly associated with Δ Z-QCT.
Conclusions  This longitudinal study suggests that the effect of chronic GH excess on spinal trabecular bone mass seems to be anabolic in active eugonadal patients but not in hypogonadal ones.  相似文献   
97.
98.
Cardiovascular magnetic resonance (CMR) imaging is widely established, free of radioactive material or ionizing radiation, and the accepted noninvasive gold standard for numerous noninvasive cardiac markers. Using a technique called T2-weighted imaging, CMR can be used to assess myocardial edema as a reliable marker for acute, potentially reversible myocardial injury. Contrast agents are not required as the myocardial free water content affects the magnetic properties of the tissue, thus providing inherent image contrast. In this review, we illustrate the utility of T2-weighted techniques in the assessment of myocardial edema in a range of clinical scenarios. The detection of myocardial edema is clinically relevant in many acute settings and may be further helpful to better understand the pathophysiology of many non-acute clinical diseases. Currently, T2-weighted CMR represents the only imaging modality that can accurately depict and quantify the presence of myocardial edema in a noninvasive fashion. Thus, T2-weighted imaging should be included in a comprehensive CMR imaging protocol, especially if an acute injury is suspected.  相似文献   
99.
Whether, and to what extent, β2-agonists protect against respiratory muscle overloading and breathlessness during bronchoconstriction remains to be defined in patients with asthma. In a double blind placebo-controlled study, 100 μg of fenoterol were administered to six stable asthmatics before a bronchial provocation test, performed by inhaling doubling concentrations of histamine from a Devilbiss 646 nebulizer. We recorded breathing pattern (tidal volume VT, inspiratory time TI, total time of the respiratory cycle TTOT), inspiratory capacity (IC), dynamic pleural pressure swing (Pplsw), total lung resistance (RL) and FEV1. VTwas expressed both in actual values and as % of IC. Changes in VT(%IC) during histamine inhalation reflected changes in dynamic end-inspiratory lung volume (EILV). Pplswwas expressed as % of maximal (the most negative in sign) pleural pressure, obtained under control conditions during a sniff manoeuvre (Pplsn). Pplsw(%Pplsn) is an index of inspiratory muscle effort. The test ended when the concentration of histamine which caused a decrease in FEV1of ≥40% post-saline was reached. Dyspnoea rating was scored by a modified Borg scale. At the ultimate degree of bronchoconstriction (UDB) with histamine: (i) decrease in FEV1was similar after placebo and fenoterol, while increase in RLwas lower after fenoterol (P<0.005); (ii) VT(%IC) increased less after fenoterol (P<0.027); (iii) increases in Pplsw(%Pplsn) was lower after fenoterol (P<0.001); (iv) ΔBorg (from saline) was lower (P<0.01) after fenoterol; (v) differences in ΔBorg, from placebo to fenoterol, related to concurrent changes in VT(%IC) (r2=0.67). In conclusion, at UDB 100 μg of fenoterol produced a beneficial effect on the degree of inspiratory muscle loading and breathlessness, an effect greater than it would be expected from measuring FEV1alone.  相似文献   
100.
Microscopic examination of blood smears remains the gold standard for malaria diagnosis, but is labor-intensive and requires skilled operators. Rapid dipstick technology provides a potential alternative. A study was conducted in The Gambia to compare the performance of OptiMAL, an immunochromatographic antigen detection assay for the diagnosis of malaria using parasite lactate dehydrogenase, against standard microscopy in patients with suspected malaria. For initial diagnosis of Plasmodium falciparum, irrespective of stage, this assay had a sensitivity of 91.3%, a specificity of 92%, a positive predictive value of 87.2%, and a negative predictive value of 94.7%. The sensitivity of the test decreased markedly at parasitemias < 0.01%. This assay can be used for the diagnosis of malaria in areas where microscopy is not available and for urgent malaria diagnosis at night and at weekends, when routine laboratories are closed and when relatively inexperienced microscopists may be on duty.  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