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   974篇
  免费   55篇
  国内免费   2篇
耳鼻咽喉   11篇
儿科学   34篇
妇产科学   34篇
基础医学   111篇
口腔科学   45篇
临床医学   53篇
内科学   133篇
皮肤病学   5篇
神经病学   105篇
特种医学   22篇
外科学   189篇
综合类   33篇
预防医学   68篇
眼科学   14篇
药学   124篇
中国医学   8篇
肿瘤学   42篇
  2023年   3篇
  2022年   14篇
  2021年   25篇
  2020年   22篇
  2019年   20篇
  2018年   18篇
  2017年   14篇
  2016年   30篇
  2015年   16篇
  2014年   37篇
  2013年   47篇
  2012年   49篇
  2011年   63篇
  2010年   29篇
  2009年   21篇
  2008年   41篇
  2007年   63篇
  2006年   44篇
  2005年   36篇
  2004年   37篇
  2003年   58篇
  2002年   30篇
  2001年   28篇
  2000年   18篇
  1999年   16篇
  1998年   11篇
  1997年   9篇
  1996年   13篇
  1995年   3篇
  1994年   10篇
  1993年   6篇
  1992年   12篇
  1991年   16篇
  1990年   14篇
  1989年   14篇
  1988年   17篇
  1987年   14篇
  1986年   9篇
  1985年   6篇
  1984年   11篇
  1983年   9篇
  1982年   6篇
  1981年   3篇
  1979年   10篇
  1978年   5篇
  1977年   3篇
  1971年   3篇
  1967年   4篇
  1966年   3篇
  1944年   5篇
排序方式: 共有1031条查询结果,搜索用时 364 毫秒
61.
HYPOTHESIS: A focused, surgeon-performed ultrasound examination of the common femoral veins is an accurate screening tool for the detection of common femoral vein thrombosis in high-risk, critically ill patients. DESIGN: A prospective study using a focused ultrasound examination for findings consistent with deep vein thrombosis of the common femoral veins. The results of these examinations were compared with those of duplex imaging or computed tomographic venography studies. SETTING: Surgical intensive care unit. PATIENTS: All critically ill patients who were admitted to the surgical intensive care unit and considered to be at high risk for the development of deep vein thrombosis. MAIN OUTCOME MEASURE: Presence of deep vein thrombosis in the common femoral veins. RESULTS: During a 16-month period, surgeons performed 306 ultrasound examinations on 220 critically ill surgical patients. The results included 295 true negative, 9 true positive, 1 false negative, and 1 false positive, yielding a 90.0% sensitivity, 99.6% specificity, and 99.3% accuracy. CONCLUSION: A focused, surgeon-performed ultrasound examination is a rapid and accurate screening method to detect common femoral vein thrombosis in critically ill patients as well as to examine those patients in whom pulmonary embolism is strongly suspected.  相似文献   
62.
OBJECTIVES: We previously demonstrated that calcineurin inhibitors given intravenously ameliorate experimental lung ischemia-reperfusion injury. This study evaluates whether these effects can be achieved when these agents are delivered endotracheally. METHODS: Left lungs of Long Evans rats were rendered ischemic for 90 minutes and reperfused for up to 4 hours. Treated animals received tacrolimus endotracheally at doses of 0.2, 0.1, or 0.025 mg/kg 60 minutes before ischemia. Injury was quantitated in terms of vascular permeability. Additional animals treated at a dose of 0.1 mg/kg were assessed for lung tissue myeloperoxidase content and bronchoalveolar lavage leukocyte content. Bronchoalveolar lavage fluid was assessed for cytokine and chemokine content by enzyme-linked immunosorbent assay. Tissue samples were processed for nuclear factor-kappaB activation, and blood levels of tacrolimus were measured in treated animals. RESULTS: Left lung vascular permeability was reduced in treated animals in a dose-dependent fashion compared with controls. The protective effects correlated with a 47% (0.50% +/- 0.06% vs 0.27% +/- 0.08%, respectively) reduction in tissue myeloperoxidase content (P <.004) and marked reductions in bronchoalveolar lavage leukocyte accumulation. This protection was also associated with decreased nuclear factor-kappaB activation and diminished expression of proinflammatory mediators. Blood tacrolimus levels in treated animals at 4 hours of reperfusion were undetectable. CONCLUSIONS: Tacrolimus administered endotracheally is protective against lung ischemia-reperfusion injury in our model. This protection is associated with a decrease in nuclear factor-kappaB activation. This route of tacrolimus administration broadens its potential clinical use and decreases concerns about systemic and renal toxicity. It may be a useful therapy in lung donors to protect against lung ischemia-reperfusion injury.  相似文献   
63.
Natural history of moderate aplastic anemia in children   总被引:16,自引:0,他引:16  
BACKGROUND: Moderate aplastic anemia (MAA) in children is a rare, idiopathic condition of bone marrow insufficiency that can resolve spontaneously, persist for months or years, or progress to severe aplastic anemia (SAA). We evaluated the rate of progression to SAA. METHODS: We reviewed the records of 136 children referred for evaluation of bone marrow failure from 1978 to 2002 at St. Jude Children's Research Hospital. MAA was defined by a hypocellular bone marrow (<50%) and 2 or 3 cytopenias (absolute neutrophil count <1,500/mm(3), absolute reticulocyte count <40,000/mm(3), platelet count <100,000/mm(3)) lasting at least 6 weeks. RESULTS: Twenty-four patients met the criteria for MAA. At a median follow-up of 66 months (range, 10-293), 16 patients (67%) progressed to SAA, 5 (21%) had persistent MAA, and 3 (12%) had complete resolution of MAA. No risk factors for progression could be identified. CONCLUSIONS: When childhood MAA is treated with supportive care alone, 2/3 of patients progress to SAA.  相似文献   
64.
Possible reversal of morphine-induced tolerance and dependence by bupropion was studied in mice. A 10-day repeated injection regimen was followed to induce morphine tolerance and dependence. Bupropion (2 and 5 mg/kg) per se, when chronically administered for 9 days, failed to produce any significant change in tail-flick latency compared with the control mice. Chronic administration of bupropion (2 or 5 mg/kg) during the induction phase (days 1-9) delayed the development of tolerance to the antinociceptive action of morphine and also reversed naloxone- (2 mg/kg) precipitated withdrawal jumps. On the other hand, acute administration of bupropion (2 or 5 mg/kg) on day 10, i.e., during the expression phase of morphine dependence, reduced the incidence of naloxone-precipitated withdrawal jumps without affecting tolerance to the analgesic effect. In conclusion, results of the present study suggest the potential use of bupropion in tolerance and dependence.  相似文献   
65.
The term mucositis is coined to describe the adverse effects of radiation and chemotherapy treatments. Mucositis is one of the most common adverse reactions encountered in radiation therapy for head and neck cancers, as well as in chemotherapy, in particular with drugs affecting DNA synthesis (S-phase-specific agents such as fluorouracil, methotrexate, and cytarabine). Mucositis may limit the patient's ability to tolerate chemotherapy or radiation therapy, and nutritional status is compromised. It may drastically affect cancer treatment as well as the patient's quality of life. The incidence and severity of mucositis will vary from patient to patient. It will also vary from treatment to treatment. It is estimated that there is 40% incidence of mucositis in patients treated with standard chemotherapy and this will not only increase with the number of treatment cycles but also with previous episodes. Similarly, patients who undergo bone marrow transplantation and who receive high doses of chemotherapy have a 76% chance of getting mucositis. Patients receiving radiation, in particular to head and neck cancers, have a 30% to 60% chance. The exact pathophysiology of development is not known, but it is thought to be divided into direct and indirect mucositis. Chemotherapy and/or radiation therapy will interfere with the normal turnover of epithelial, cells leading to mucosal injury; subsequently, it can also occur due to indirect invasion of Gram-negative bacteria and fungal species because most of the cancer drugs will cause changes in blood counts. With the advancement in cytology, a more precise mechanism has been established. With this understanding, we can select and target particular mediators responsible for the mucositis. Risk factors such as age, nutritional status, type of malignancy, and oral care during treatment will play important roles in the development of mucositis. Many treatment options are available to prevent and treat this condition, but none of them can completely prevent or treat mucositis. More and more pathological methods are being developed to understand this condition so that better therapeutic regimens can be selected. Emphasis also should be made in assessing the patient's psychologic condition, particular depressive disorders. This is important because treatment with antidepressants will not only contribute in lifting depression but also reduces pain somatization. Although mucositis is rarely life-threatening, it will interfere with treatment of cancer to a great extent.  相似文献   
66.
Obliterative bronchiolitis (OB) affects over half of all survivors following lung or heart-lung transplantation. Respiratory epithelial cell injury, peribronchial inflammation, and proliferation of fibrovascular tissue causing airway occlusion characterize the lesion. While peroxynitrite is known to participate in other models of acute lung injury, its role in the evolution of OB is unclear. Using a rat model of experimental OB, tracheas from Brown-Norway or Lewis rats were transplanted into Lewis recipients. Treated animals received FP-15, a peroxynitrite decomposition catalyst, at 1 mg/kg/day intraperitoneal for 14 days. Luminal obstruction, epithelial loss, and inflammatory infiltrate were examined, as was nitrotyrosine staining by immunohistochemistry in explanted tracheas. By postoperative day 14, control allografts demonstrated marked peribronchial inflammation, near complete loss of respiratory epithelium and extensive intraluminal proliferation of fibrovascular connective tissue, with a mean 83% reduction in airway cross-sectional area. Allograft recipients treated with FP-15 showed reduced nitrotyrosine formation, preservation of respiratory epithelium, limited peribronchial inflammation, and only 14% (P <.001) reduction in airway cross-sectional area. Peroxynitrite therefore appears to play a role in the development of obliterative bronchiolitis in rats. The peroxynitrite decomposition catalyst, FP-15, is protective when administered daily and warrants investigation into its potential clinical utility.  相似文献   
67.
BACKGROUND: Elevated blood pressure is a leading cause of morbidity and mortality throughout the world, as a major contributor to cardiovascular diseases. Blood pressure tends to vary cross-culturally and studies to address the influence of acculturization/modernization on blood pressure are limited from India, particularly from Andhra Pradesh. AIM: To provide information on blood pressure levels and variability across population groups from the State of Andhra Pradesh, India, and to examine the influence of acculturization/modernization on blood pressure levels. SUBJECTS AND METHODS: The blood pressure levels among 1316 individuals (646 men and 670 women) belonging to two tribal (Khondh and Valmiki) and two caste groups (Wadabalija and Settibalija) from rural and urban areas from Andhra Pradesh were collected. Analysis of covariance (ANCOVA) was used to examine the effect of age and sex, and population differences. RESULTS: The distribution of blood pressure showed significant variability among these population groups. Higher levels of blood pressure were noticed in an acculturizing tribe, the Valmiki, than among the Khondh, a traditional tribal population. The results indicate that age had significant effect on both systolic and diastolic blood pressure levels. Also, the systolic blood pressure was relatively more sensitive than diastolic blood pressure to the effect of age. The sex did not contribute significantly to the variability of blood pressure. CONCLUSIONS: The study revealed significant population differences in the variability of blood pressure, with higher levels among acculturizing tribal population than the non-acculturizing group. But no significant variation was noticed between rural and urban slum dwellers. Age had a significant effect on blood pressure levels.  相似文献   
68.
Patients with asthma are a target group for medication with beta2-agonists, often in combination with corticosteroids. Salbutamol is commonly marketed as racemate. R-Salbutamol carries beta2-agonistic property whereas S-salbutamol does not. The racemate undergoes stereoselective sulphatisation by sulfotransferases mainly in the gut and liver, so that S-salbutamol rests for a longer time in the body and reaches higher plasma levels than R-salbutamol. Ten patients with mild stable asthma and at present without cortisone medication were given racemic salbutamol as ventoline 4 mg orally. Plasma and urine levels were estimated until 24 hr after ingestion. For comparison healthy volunteers were treated in the same way. The group of asthma patients was then treated with budesonide inhalations 800 microg daily for one week and the initial programme resumed. Non-cortisone-treated asthmatic patients displayed higher levels of both R- and S-salbutamol in plasma than did healthy volunteers after one single ingestion of racemic salbutamol (CMAX both comparisons P<0.05). Plasma levels of salbutamol isomers in cortisone-treated asthmatic patients resembled the levels in volunteers. The most plausible explanation for the discrepancy in values between asthmatic patients and volunteers is a defective metabolic function by asthmatic patients possibly enzymatic in origin.  相似文献   
69.
Inflammation is the response of living tissue to damage. Cytokines play an important role in inflammatory processes. FK506 (tacrolimus), an immunosuppressant, is known to reduce the activation of microglia in vitro and affect the expression of various cytokines like interleukin-1, interleukin-6 and tumor necrosis factor. With this background the present study was designed to explore the effect of FK506 in animal models of acute inflammation and experimental pleurisy. Acute inflammation in rats was induced by intraplantar injection of carrageenan (1%, w/v). Experimental pleurisy was induced in rats by intrapleural injection of carrageenan (2%, w/v). Pretreatment with FK506 (0.5–3 mg/kg p.o.) significantly and dose-dependently reduced carrageenan-induced increase in paw volume, as well as carrageenan-induced inflammatory nociception. FK506 (1 and 3 mg/kg p.o.) inhibits exudate formation and migration of polymorhonuclear leukocytes and monocytes in carrageenan-induced experimental pleurisy. The myeloperoxidase enzyme level was significantly increased in carrageenan-treated animals, which was significantly reversed by FK506 treatment. The results of the present study suggest the potential anti-inflammatory properties of FK506 against carrageenan-induced acute inflammation and experimental pleurisy.  相似文献   
70.
Flame Atomic Absorption Spectrometer method has been used to determine Zinc and Iron in serum samples of humans with various cataracts. The method for the determination of Zinc includes the dilution of serum (1+9) with water soluble n-butanol 6% (v/v) and calibration with standards containing Zinc in 0.5%(v/v) HCl, diluted in the same way. The method for the determination of Iron includes deprotenization by diluting the serum (1+9) with trichloro acetic acid 5% (v/v). The values obtained for persons with several cataracts were compared with the values reported in the literature for normal persons. Further, the reliability of Flame Atomic Absorption Spectrometer method for the determination of Zinc and Iron in serum samples of humans with several cataracts was tested by inter-comparison with Inductively Coupled Plasma Atomic Emission Spectrometer.  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