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   912篇
  免费   51篇
  国内免费   18篇
耳鼻咽喉   4篇
儿科学   26篇
妇产科学   13篇
基础医学   85篇
临床医学   71篇
内科学   278篇
皮肤病学   15篇
神经病学   85篇
特种医学   18篇
外科学   195篇
综合类   3篇
预防医学   29篇
眼科学   28篇
药学   71篇
中国医学   2篇
肿瘤学   58篇
  2023年   11篇
  2022年   21篇
  2021年   32篇
  2020年   14篇
  2019年   33篇
  2018年   29篇
  2017年   19篇
  2016年   34篇
  2015年   33篇
  2014年   44篇
  2013年   33篇
  2012年   58篇
  2011年   71篇
  2010年   38篇
  2009年   25篇
  2008年   49篇
  2007年   59篇
  2006年   50篇
  2005年   37篇
  2004年   45篇
  2003年   47篇
  2002年   43篇
  2001年   15篇
  2000年   6篇
  1999年   10篇
  1998年   12篇
  1997年   7篇
  1996年   6篇
  1995年   4篇
  1994年   4篇
  1993年   6篇
  1992年   18篇
  1991年   8篇
  1990年   10篇
  1989年   13篇
  1988年   4篇
  1987年   2篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   4篇
  1979年   4篇
  1978年   3篇
  1977年   2篇
  1976年   1篇
  1975年   5篇
  1974年   1篇
  1967年   1篇
  1966年   2篇
  1965年   1篇
排序方式: 共有981条查询结果,搜索用时 15 毫秒
41.
BACKGROUND: Giant myomas of the uterus are uncommon, particularly in developed countries. CASE: This report illustrates a case of a woman with a bilobated giant myoma of the uterus weighed in total 27.7 kg. The patient had an abdominal distension first noted 18 months before and the personal history evidenced difficulties in walking and tiredness. Abdominal hysterectomy and bilateral salpingo-oophorectomy were carried out. CONCLUSIONS: The knowledge of the different clinical manifestation of these myomas may allow to face that with adequate perioperative care, in order to assure a carefully and successfully surgery, although sometimes a benign pathology may be not easy to suspect in a first time.  相似文献   
42.

Purpose

We retrospectively report strategies used for medulloblastoma patients progressing after craniospinal irradiation where we aimed for: symptom control, a satisfactory quality of life, accrual in phase 1–2 trials, when available, and the first two conditions could no longer be satisfied by already experienced second-line strategies.

Methods

Surgery was used in cases of doubtful relapse or when only one site was affected. Radiotherapy was given whenever possible, especially to relieve symptoms. The main chemotherapy regimens were oral temozolomide/etoposide, intravenous (iv.) cisplatin/etoposide, iv. gemcitabine/oxaliplatin, an oral sonic hedgehog pathway inhibitor and oral melphalan.

Results

Between 1998 and 2011, we treated 18 patients relapsed after median 20 months. Nine had relapsed locally, four had dissemination, three single metastases, and two had one synchronous local and metastatic recurrence. Responses to chemotherapy were seen in 32 % of cases. The median hospital stay for treatments/complications was 19 days. The 1- and 3-year progression-free survival (PFS) rates were 28?±?10 % and 0 %, respectively, for OS, they were 44?±?12 % and 22?±?10 % but no patient was cured. The median PFS after a first relapse was 7 months (range 1–29); the median OS was 7 months (range 4–44). No patients died due to treatment toxicity. Late recurrence (more than 1–2 years after diagnosis) and involvement of single sites were favorable prognostic factors.

Conclusions

Without succeeding in patients cure, we ensured them further treatment with short hospital stay thus affording low personal and social costs. The chances of cure may emerge from tailored therapies according to genetic stratification.  相似文献   
43.
Background: Alcohol addiction is a complex brain disease caused by alterations in crucial neurotransmitter systems, including gamma‐aminobutyric acid (GABA) and glutamate. These disturbances could be revealed by changes in cortical excitability parameters, as assessed by transcranial magnetic stimulation (TMS). This study was aimed to further investigate the complex pathophysiology of alcohol withdrawal syndrome (AWS). Methods: Motor cortex excitability was examined in 13 subjects with AWS in a mild predelirial state, in 12 chronic alcoholics and in 15 age‐matched control subjects, using a range of TMS protocols. Central motor conduction time, resting and active motor threshold, duration of the cortical silent period, short latency intracortical inhibition (SICI), and intracortical facilitation (ICF) to paired TMS were examined. Results: Intracortical facilitation was significantly increased in the AWS patients when compared with the chronic alcoholics and the control subjects. The other TMS parameters did not differ significantly from the controls. Administration of a single oral dose of the glutamatergic antagonist riluzole in a subgroup of 8 patients significantly reduced ICF; motor threshold and SICI were not affected by riluzole. Conclusion: Transcranial magnetic stimulation shows a selective increase in intracortical facilitation after ethanol withdrawal. Our findings support the theory that altered glutamatergic receptor function plays an important role in the pathogenesis of human alcohol withdrawal. This study provides further physiological evidence that antiglutamatergic approaches represent an efficacious alternative for treating alcohol withdrawal symptoms.  相似文献   
44.
45.
46.
Osteoarthritis (OA) is a complex disease whose pathogenesis includes the contribution of biomechanical and metabolic factors which, altering the tissue homeostasis of articular cartilage and subchondral bone, determine the predominance of destructive over productive processes. A key role in the pathophysiology of articular cartilage is played by cell/extra-cellular matrix (ECM) interactions, which are mediated by cell surface integrins. In a physiologic setting, integrins modulate cell/ECM signaling, essential for regulating growth and differentiation and maintaining cartilage homeostasis. During OA, abnormal integrin expression alters cell/ECM signaling and modifies chondrocyte synthesis, with the following imbalance of destructive cytokines over regulatory factors. IL-1, TNF-alpha and other pro-catabolic cytokines activate the enzymatic degradation of cartilage matrix and are not counterbalanced by adequate synthesis of inhibitors. The main enzymes involved in ECM breakdown are metalloproteinases (MMPs), which are sequentially activated by an amplifying cascade. MMP activity is partially inhibited by the tissue inhibitors of MMPs (TIMPs), whose synthesis is low compared with MMP production in OA cartilage. Intriguing is the role of growth factors such as TGF-beta, IFG, BMP, NGF, and others, which do not simply repair the tissue damage induced by catabolic factors, but play an important role in OA pathogenesis.  相似文献   
47.
Chronic hypoxia: a model for cyanotic congenital heart defects   总被引:4,自引:0,他引:4  
OBJECTIVE: The postoperative course of cyanotic children is generally more complicated than that of acyanotic children. A possible reason is reoxygenation injury at the beginning of cardiopulmonary bypass. In this study we tested the hypothesis that reoxygenation of chronically hypoxic hearts is worse than that of normoxic hearts. METHODS: Two groups of rats (n = 9 each) were exposed to either room air (fraction of inspired oxygen, 0.21%) or chronic hypoxia (fraction of inspired oxygen, 0.10%) for 2 weeks. Hearts were then isolated and perfused for 30 minutes with hypoxic buffer (oxygen saturation, 10%), followed by 30 minutes of reoxygenation (oxygen saturation, 100%). RESULTS: In hypoxic rats hematocrit values, hemoglobin concentrations, and red cells were higher (69% +/- 6% vs 40% +/- 6%, 219 +/- 14 vs 124 +/- 12 g/L, and 10.30 +/- 0.6 vs 6.32 +/- 0.5/microL/1000, respectively; P <.0001); the amount of ingested food was less (22.3 +/- 4.8 vs 30.7 +/- 3.9 g/d, P <.001), as was the amount of ingested water (21.0 +/- 3.1 vs 50.4 +/- 14.6 mL/d, P <.0001); and body weight was lower (182 +/- 14.2 vs 351 +/- 40.1 g, P <.0001), as was heart weight (1107 +/- 119 vs 1312 +/- 128 mg, P <.005). The heart weight/body weight ratio was higher (6.10 +/- 0.8 vs 3.74 +/- 0.1 mg/g, P <.0001). Systolic and diastolic functions, not different during the hypoxic baseline period, were more impaired in hypoxic than in normoxic hearts after the reoxygenation, whereas coronary resistance remained lower. During the hypoxic perfusion, the venous partial pressure of oxygen remained low in both groups, whereas during reoxygenation, partial pressure of oxygen was higher in hypoxic hearts, with a lower (P <.01) oxygen uptake. During hypoxic baseline adenosine triphosphate turnover, lactate production and lactate turnover were lower in hypoxic hearts (P <.005, P <.0001, and P <.0001, respectively). CONCLUSIONS: Body and blood values are severely affected by chronic hypoxia, and the cardiac effects of uncontrolled reoxygenation after chronic hypoxia are more severe than after acute hypoxia.  相似文献   
48.
BACKGROUND: The purpose of this study was to evaluate the correlation between the midterm angiographic results of mammary artery grafts and the preoperative stenosis of the target vessel. METHODS: We analyzed preoperative and postoperative angiograms of 93 patients who underwent postoperative midterm (> or = 3 years) angiograms of an internal mammary artery (IMA) to left anterior descending artery graft for clinical or study purposes. Patients were divided into three groups on the basis of the percentage of the coronary artery stenosis at preoperative angiography: < 70%, 70% to 90%, and > 90% stenosis. RESULTS: Preoperative characteristics were similar in the three groups. The overall incidence of IMA occlusion was 19% in the entire population, without significant differences between groups (19% versus 29% versus 14%). The mean mammary artery diameter significantly increased in direct proportion to the severity of the coronary stenosis (2.0 +/- 0.2 mm in the < 70% versus 2.5 +/- 0.3 mm in the 70% to 90% and 2.7 +/- 0.4 mm in the > 90% series; p < 0.05). CONCLUSIONS: Chronic native competitive flow does not significantly affect midterm graft status but does influence mammary graft diameter.  相似文献   
49.
Management of pulmonary embolism during acrylic vertebroplasty   总被引:14,自引:0,他引:14  
A 55-year-old man diagnosed with osteogenesis imperfecta had multiple pulmonary embolism from acrylic cement during vertebroplasty. The patient immediately developed respiratory distress, renal failure, and right cardiac failure. A computed tomographic scan showed the presence of cement in the right and left pulmonary arteries, and in both lungs. Cardiac and respiratory functions did not improve with medical treatment, therefore the patient underwent pulmonary artery embolectomy. Cement was easily removed from both pulmonary arteries. The patient quickly recovered from respiratory and cardiac failure. We believe pulmonary embolectomy is a reliable and effective procedure to treat this rare and dreadful complication of acrylic vertebroplasty.  相似文献   
50.
In this study, the authors attempted to validate answers to smoking-habit questions contained in the European Community Respiratory Health Survey questionnaire. The respondents were invited to visit the chest clinic at Verona, Italy, and their serum cotinine levels were measured. The authors invited each of 504 subjects to complete a respiratory interview and to give a blood sample for a radioimmunoassay serum cotinine measurement. A total of 375 subjects responded, of whom 129 were smokers (34.4%), 79 were exsmokers (21.1%), and 167 (44.5%) had never smoked. Exposure to environmental tobacco smoke was reported by 216 subjects (57.6% [mean exposure = 3.8 hr/day (+/- 3.4 hr/day standard deviation)]). In smokers, serum cotinine levels were directly related to the number of cigarettes smoked/day. The authors excluded from analysis nonsmokers who had serum cotinine levels that were > or = 14 ng/ml, and the resulting mean values were 1.7 ng/ml (+/- 2.1 ng/ml standard deviation) in nonsmokers unexposed to environmental tobacco smoke and 2.6 ng/ml (+/- 2.6 ng/ml standard deviation) (p < .002) in nonsmokers exposed to environmental tobacco smoke. There was a relationship between serum cotinine levels and hours of exposure to environmental tobacco smoke (R2 = .136, p < .05). Serum cotinine, which is an objective and accepted measure of tobacco exposure, confirmed the validity of the European Community Respiratory Health Survey questionnaire with respect to smoking habits and environmental tobacco smoke exposure.  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