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   337篇
  免费   8篇
儿科学   1篇
妇产科学   3篇
基础医学   42篇
口腔科学   45篇
临床医学   22篇
内科学   74篇
皮肤病学   9篇
神经病学   40篇
特种医学   7篇
外科学   44篇
综合类   2篇
预防医学   16篇
眼科学   10篇
药学   22篇
肿瘤学   8篇
  2022年   7篇
  2021年   8篇
  2020年   5篇
  2019年   2篇
  2018年   2篇
  2017年   3篇
  2016年   4篇
  2015年   9篇
  2014年   10篇
  2013年   7篇
  2012年   18篇
  2011年   19篇
  2010年   7篇
  2009年   11篇
  2008年   20篇
  2007年   30篇
  2006年   22篇
  2005年   16篇
  2004年   11篇
  2003年   10篇
  2002年   27篇
  2001年   8篇
  2000年   10篇
  1999年   13篇
  1998年   3篇
  1997年   3篇
  1996年   2篇
  1995年   4篇
  1994年   2篇
  1992年   3篇
  1991年   5篇
  1986年   1篇
  1985年   3篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1979年   3篇
  1978年   2篇
  1977年   1篇
  1974年   1篇
  1973年   3篇
  1972年   3篇
  1971年   2篇
  1970年   6篇
  1969年   3篇
  1968年   1篇
  1962年   2篇
  1961年   1篇
  1958年   2篇
排序方式: 共有345条查询结果,搜索用时 31 毫秒
121.
BACKGROUND AND OBJECTIVE: The objective of this study was to develop a specific instrument for measuring health-related quality of life (HRQL) in patients receiving home mechanical ventilation (HMV). METHODS: The Severe Respiratory Insufficiency (SRI) Questionnaire was developed and tested for its psychometric properties following a multicentric clinical trial including 226 patients receiving HMV (mean age 57.3+/-14.0 years). RESULTS: Forty-nine items passed the selection process and were allocated to seven subscales: Respiratory Complaints, Physical Functioning, Attendant Symptoms and Sleep, Social Relationships, Anxiety, Psychologic Well-Being, and Social Functioning. Cronbach's alpha was >0.7 in all subscales and >0.8 in four subscales indicating high internal consistency reliability. Construct validity was confirmed by factor analysis, indicating one summary scale that accounts for 59.8% of the variance. Concurrent validity was confirmed by correlating subscales of the SRI and the SF-36 (0.21相似文献   
122.
The synthesis and the effect of a combination of 6-glycine and 14-phenylpropoxy substitutions in N-methyl- and N-cycloproplymethylmorphinans on biological activities are described. Binding studies revealed that all new 14-phenylpropoxymorphinans (11-18) displayed high affinity to opioid receptors. Replacement of the 14-methoxy group with a phenylpropoxy group led to an enhancement in affinity to all three opioid receptor types, with most pronounced increases in δ and κ activities, hence resulting in a loss of μ receptor selectivity. All compounds (11-18) showed potent and long-lasting antinociceptive effects in the tail-flick test in rats after subcutaneous administration. For the N-methyl derivatives 13 and 14, analgesic potencies were in the range of their 14-methoxy analogues 9 and 10, respectively. Even derivatives 15-18 with an N-cyclopropylmethyl substituent acted as potent antinociceptive agents, being several fold more potent than morphine. Subcutaneous administration of compounds 13 and 14 produced significant and prolonged antinociceptive effects mediated through peripheral opioid mechanisms in carrageenan-induced inflammatory hyperalgesia in rats.  相似文献   
123.
High-flow oxygen via nasal cannulas represents a new noninvasive treatment option for patients with hypoxemic respiratory failure. Here, a warmed and humidified air–oxygen mixture is delivered at a high-flow rate of 20–60 l/min and with a defined fraction of inspired oxygen (FiO2). High-flow oxygen is a further treatment option that is increasingly used next to conventional oxygen support and noninvasive positive pressure ventilation in the intensive care unit and is in focus of current research. Studies comparing high-flow oxygen and both conventional oxygen support and noninvasive positive-pressure ventilation in hypoxemic respiratory failure have suggested comparable treatment success and outcome. Furthermore, high-flow oxygen is reportedly better tolerated by patients with fewer side effects compared to conventional oxygen support and noninvasive positive-pressure ventilation.  相似文献   
124.
Congenital central hypoventilation syndrome (CCHS) typically presents in the newborn period. A case series of five adults is presented, each heterozygous for a documented polyalanine expansion mutation in the PHOX2B gene and evidence of nocturnal alveolar hypoventilation. All cases had symptoms in childhood, but survived to adulthood without ventilatory support. After identification of physiologic compromise, artificial ventilation was initiated. These adults have the mildest of the CCHS-related PHOX2B polyalanine expansion mutations, coding for only five extra alanines; three of the adults have affected offspring. Report of these cases should lead to a more rapid identification of CCHS presenting in adulthood.  相似文献   
125.
OBJECTIVE AND BACKGROUND: Endotracheal tube resistance is known to be flow-dependent and this understanding has improved the application of invasive ventilation. However, similar physiological studies on the interface between patients and non-invasive positive pressure ventilation (NPPV) have not been performed. Therefore, this study was aimed at investigating the resistance of nasal masks used for NPPV. METHODOLOGY: The flow-dependent pressure drop of the small (S), medium-small (MS) and medium (M) Contour Nasal Mask (Respironics Inc., Murrysville, PA, USA) was measured with and without a connecting tube (length 18 cm, internal diameter 1.5 cm) in a laboratory study. The resistance was calculated by Rohrer's equation using the standard least-squares-fit technique. The present study explicitly differentiated between the resistance of the nasal mask alone when measured against atmosphere and the additional resistance caused by the nasal mask when airtightly fitted to a model head (interaction with the face). RESULTS: Higher flow rates resulted in a non-linearly increasing pressure drop across the interface. This flow-dependent resistance of the S/MS/M mask was comparably low when not interacting with the face, but increased when interacting with the face. This flow-dependent resistance of the mask was several-fold higher when adding the connection tube and tended to be higher during expiration. CONCLUSION: There is a non-linear flow-dependent pressure drop across the nasal mask which is low and independent of its size, but increases when interacting with the face. The connecting tube is the major determinant of the resistance originating from facial appliances used for NPPV.  相似文献   
126.
BACKGROUND: Dyspnea and fatigue are frequent but poorly understood symptoms in sarcoidosis patients. This study was aimed at assessing the clinical impact of inspiratory muscle impairment on dyspnea and exercise tolerance. This is the first study using nonvolitional tests that are independent of the patient's cooperation and motivation in addition to volitional tests of inspiratory muscle strength in patients with sarcoidosis. METHODS: Peak maximal inspiratory mouth pressure (Pimaxpeak), maximal inspiratory pressure sustained for 1.0 s (Pimax1.0), twitch mouth pressure (TwPmo), lung function test results, blood gas measurements, 6-min walking distance (6MWD), and Borg dyspnea scale (BDS) scores were assessed in 24 male sarcoidosis patients and 24 healthy male control subjects matched for age and body mass index. RESULTS: Mean (+/- SD) Pimaxpeak (95.2 +/- 25.3% vs 124.6 +/- 23.4% predicted, respectively; p < 0.001) and Pimax1.0 (85.6 +/- 31.4% vs 125.8 +/- 26.8% predicted, respectively; p < 0.001) were lower in sarcoidosis patients compared to control subjects. TwPmo tended to be lower in sarcoidosis patients, and there were three patients who had TwPmo values of < 1.0 kPa, which is a strong indicator of inspiratory muscle weakness. The mean 6MWD was 582 +/- 97 m in sarcoidosis patients and 638 +/- 65 in control subjects (p = 0.025). The mean BDS score was higher in sarcoidosis patients (3.3 +/- 1.7 vs 0.2 +/- 0.5, respectively; p < 0.001). Compared to maximal inspiratory pressure, lung function parameters, and blood gas levels, TwPmo was the strongest predictor for 6MWD (r = 0.663; p = 0.003) and BDS score (r = 0.575; p = 0.012) in sarcoidosis patients following multiple linear regression analysis. CONCLUSIONS: Impairment of inspiratory muscle strength occurs in sarcoidosis patients, and has been suggested to be an important factor causing dyspnea and reduced walking capacity, but this is only reliably detectable when using nonvolitional tests of inspiratory muscle strength.  相似文献   
127.
One-day-old turkey poults were vaccinated against histomonosis (syn. histomoniasis) via the oral route by application of in vitro attenuated Histomonas meleagridis. Subsequently, two different groups composed of 14 birds each were challenged cloacally with highly virulent histomonads after 2 or 4 weeks. Two additional groups of non-vaccinated birds were infected with the challenge inoculum at the same time points. In addition, a group of 19 birds, of which 14 were vaccinated but not challenged, were kept for clinical and serological examinations. Non-vaccinated and non-challenged birds (n=10) represented the negative control group. All non-vaccinated but infected birds and 10 out of 14 vaccinated turkeys challenged 2 weeks post vaccination (w.p.v.) contracted severe histomonosis. Turkeys challenged 4 w.p.v. and all remaining birds used in this experiment did not show any pathognomonic clinical signs. In addition, no adverse effect regarding the weight gain could be observed in birds that were vaccinated but not challenged. The excretion of attenuated and virulent live histomonads was observed very infrequently by re-isolation, but transmission to in-contact birds was very efficient. Presence of antibodies was first noticed 3 w.p.v. and antibody levels remained above the cut-off value until termination of the experiment at 16 w.p.v. The present experiment demonstrates for the first time the potential efficacy of in vitro attenuated histomonads used as an orally applied vaccine to 1-day-old turkeys for protection against fatal histomonosis without affecting performance.  相似文献   
128.
The improvement of health-related quality of life (HRQL) is an important goal in managing patients with chronic respiratory failure (CRF) receiving long-term oxygen therapy (LTOT) and/or domiciliary noninvasive ventilation (NIV). Two condition-specific HRQL questionnaires have been developed to specifically assess these patients: the Maugeri Respiratory Failure Questionnaire (MRF) and the Severe Respiratory Insufficiency Questionnaire (SRI). The MRF is more advantageous in its ease of completion; conversely, the SRI measures diversified health impairments more multi-dimensionally and discriminatively with greater balance, especially in patients receiving NIV. The SRI is available in many different languages as a result of back-translation and validation processes, and is widely validated for various disorders such as chronic obstructive pulmonary disease, restrictive thoracic disorders, neuromuscular disorders, and obesity hypoventilation syndrome, among others. Dyspnea and psychological status were the main determinants for both questionnaires, while the MRF tended to place more emphasis on activity limitations than SRI. In comparison to existing generic questionnaires such as the Medical Outcomes Study 36-item short form (SF-36) and disease-specific questionnaires such as the St. George's Respiratory Questionnaire (SGRQ) and the Chronic Respiratory Disease Questionnaire (CRQ), both the MRF and the SRI have been shown to be valid and reliable, and have better discriminatory, evaluative, and predictive features than other questionnaires. Thus, in assessing the HRQL of patients with CRF using LTOT and/or NIV, we might consider avoiding the use of the SF-36 or even the SGRQ or CRQ alone and consider using the CRF-specific SRI and MRF in addition to existing generic and/or disease-specific questionnaires.  相似文献   
129.

Background

Chronic central serous chorioretinopathy (CSR) is an idiopathic, often self-limiting disease usually occurring in younger patients. A characteristic sign of CSR is a serous detachment of the neurosensory retina. Prognosis with regard to visual acuity is generally good. The disease is chronic or recurrent in up to 30% of cases. There is a risk for the development of secondary choroidal neovascularization. Therapeutic options include photocoagulation or photodynamic therapy (PDT) with verteporfin. In recent years there have been several approaches aiming to minimize the side-effects of PDT and the treatment protocols were designated half-dose, reduced fluence or low fluence PDT.

Patients and Methods

A total of 7 eyes from 6 male patients with CSR were analyzed retrospectively. Beforehalf-dose PDT and at the end of follow-up best corrected visual acuity and retinal thickness were measured by spectral domain-optical coherence tomography.

Results

The mean age of the patients was 40.7?±?10.3 years, 5 eyes were treated with a single session of half-dose PDT (25?J?/?cm2), 1 with 2 PDTs and 1 with a total of 3 PDTs. Mean follow-up was 79.8?±?104.5 months. Mean visual acuity (Snellen) before PDT was 0.4?±?0.2 and 0.4?±?0.3 after PDT (p?=?0.49). During the observation period the mean retinal thickness (RT) decreased from 479???m?±?233 to 242???m?±?60 (p?=?0.08).

Conclusions

Half-dose PDT is a safe option for patients with long-standing CSR. All patients showed a decrease of retinal thickness, 6 eyes showed a total resolution of subretinal fluid and 5 eyes also showed functional improvement.  相似文献   
130.
BACKGROUND: The goal of this study was to evaluate clinically and histologically the healing of advanced intrabony defects following regenerative periodontal surgery with an enamel matrix derivative (EMD) combined with a new biphasic calcium phosphate (BCP). METHODS: Ten subjects, each of them displaying advanced combined 1- and 2-wall intrabony defects around teeth scheduled for extraction because of advanced chronic periodontitis and further prosthodontic considerations, were included in the study. The defects were consecutively treated with a combination of EMD + BCP. A notch was placed at the most apical extent of the calculus present on the root surface or at the most apical part of the defect (if no calculus was present) to serve as a reference for the histologic evaluation. At 9 months after regenerative surgery, nine of 10 teeth were extracted with some of their surrounding soft and hard tissues and processed for histologic evaluation. RESULTS: There were no adverse effects related to EMD or the graft material used in any of the treated subjects. One tooth was not extracted because of the excellent clinical outcome. The clinical measurements at the nine biopsied teeth demonstrated a mean probing depth reduction of 3.3 +/- 1.4 mm and a mean clinical attachment level gain of 3.0 +/- 1.6 mm. The histologic findings indicated formation of cementum with inserting collagen fibers to a varying extent. A long junctional epithelium was observed in three of the nine biopsies. Mean new connective tissue attachment (i.e., new cementum with inserting collagen fibers) varied from 0.0 to 2.1 mm. The amount of newly formed bone was limited and varied from 0.0 to 0.7 mm. At 9 months, graft particles were still present and were mostly encapsulated in connective tissue, whereas formation of bone around the graft particles was observed only occasionally. Direct contact between the graft particles and the root surface (cementum or dentin) was not observed in any of the analyzed specimens. CONCLUSIONS: The combination of EMD with a BCP bone substitute did not interfere with the regenerative potential reported for EMD and may result in formation of new cementum with an associated periodontal ligament. However, the combination of EMD + BCP resulted in no to minimal new bone formation.  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