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   1085篇
  免费   62篇
  国内免费   11篇
耳鼻咽喉   2篇
儿科学   86篇
妇产科学   10篇
基础医学   100篇
口腔科学   35篇
临床医学   137篇
内科学   231篇
皮肤病学   19篇
神经病学   24篇
特种医学   305篇
外科学   68篇
综合类   10篇
预防医学   30篇
眼科学   6篇
药学   36篇
肿瘤学   59篇
  2021年   8篇
  2020年   4篇
  2019年   5篇
  2018年   15篇
  2017年   3篇
  2016年   7篇
  2015年   15篇
  2014年   17篇
  2013年   23篇
  2012年   12篇
  2011年   14篇
  2010年   31篇
  2009年   30篇
  2008年   14篇
  2007年   32篇
  2006年   20篇
  2005年   23篇
  2004年   21篇
  2003年   9篇
  2002年   13篇
  2001年   9篇
  2000年   10篇
  1999年   23篇
  1998年   96篇
  1997年   70篇
  1996年   76篇
  1995年   54篇
  1994年   55篇
  1993年   61篇
  1992年   13篇
  1991年   10篇
  1990年   14篇
  1989年   39篇
  1988年   26篇
  1987年   38篇
  1986年   23篇
  1985年   29篇
  1984年   23篇
  1983年   17篇
  1982年   24篇
  1981年   23篇
  1980年   28篇
  1979年   6篇
  1978年   17篇
  1977年   18篇
  1976年   20篇
  1975年   13篇
  1933年   1篇
  1932年   1篇
  1930年   1篇
排序方式: 共有1158条查询结果,搜索用时 31 毫秒
101.
Detailed invasive haemodynamic studies were performed in 27of 32 patients with severe tetanus. Nineteen had severe uncomplicatedtetanus and eight had associated major complications, chieflyinfection and pulmonary complications. The results were comparedwith those obtained from 15 healthy male volunteers who servedas controls. There were two deaths in 32 patients (mortality6.25 per cent). Severe tetanus without major complications wascharacterized by a high output hyperkinetic circulatory statewith tachycardia (heart rate 131 (19.2) beats/minute), increasedstroke volume index (43.1 (10.7) ml/m2), increased cardiac index(5.48 (0.94)1/min/m2) and a normal left ventricular stroke workindex (60.5 (15.9) g/m/m2). Volume loading demonstrated a significanthaemodynamic response and increased vascular capacitance. Evenso the maximum percent rise from baseline values of these indicesafter volume load was significantly higher in controls (p <0.001). Autonomic cardiovascular disturbances affected bothsympathetic and parasympathetic activity. Hypertension and tachycardiaalternating with hypotension and bradycardia were related tosudden fluctuations in systemic vascular resistance. Our studiessuggested some degree of myocardial dysfunction in patientswith severe uncomplicated tetanus. The haemodynamics of severetetanus were masked and altered by complicating infection, pneumonia,and atelectasis.  相似文献   
102.
This article reviews the pathophysiology and pharmacology of emesis in relation to migraine pathogenesis. Also, the place of antiemetic and gastrointestinal prokinetic agents in current and future acute migraine treatment strategies is reviewed. The mechanisms of action of current and novel acute migraine therapies are considered with respect to the neurogenic and vascular hypotheses. Control of migraine-associated nausea and vomiting is often achieved with the benzamide dopamine D2 receptor antagonist metoclopramide. This drug also has 5HT3 receptor antagonist activity and reproducibly stimulates gastric motility to increase the availability of orally administered drugs. Other antiemetic and gastroprokinetic agents with potential value for the treatment of migraine-associated nausea and vomiting could speed absorption of oral antimigraine therapies without central nervous system side effects. Domperidone, a dopamine D2 receptor antagonist that does not cross the blood brain barrier is relatively free of the central side-effect liability of metoclopramide. Cisapride, a benzamide 5HT4 receptor agonist gastrointestinal prokinetic drug, lacks dopamine antagonist activity. A controlled comparison of these agents as migraine co-therapies could provide information on the importance of peripheral and central mechanisms in migraine-associated nausea and vomiting and improve antimigraine treatment options.  相似文献   
103.
自美国国家骨髓库(NMDP)开展第一例无关供者移植以来,至今已有20年.NMDP目前的库容量已逾700万,已为6大洲提供了30 000多份无关供者造血干细胞.这一辉煌成就是美国国家骨髓库600多名工作人员共同努力的结果,同时也得益于广泛的国际合作,包括171个移植中心,73个供者中心,24个脐血库,97个骨髓采集中心,91个血液净化中心,26个HLA分型实验室和26个合作供者登记处.本文回顾了美国国家骨髓库的历史,阐述了20年来移植病人、移植物来源和预处理方案几方面的主要变化趋势.  相似文献   
104.
BACKGROUND: Chagas' disease, caused by the protozoan parasite Trypanosoma cruzi, is endemic to Latin America and may be transmitted in the United States via blood donated by infected immigrants. Blood- borne pathogens such as T. cruzi require supplemental testing for confirmation of seroreactivity. STUDY DESIGN AND METHODS: A study was undertaken to determine an optimal scheme for confirmation of seroreactivity in repeatedly reactive samples identified by the Chagas antibody enzyme immunoassay (EIA). The procedure for initial confirmation involves three purified antigens coated onto three separate polystyrene beads and uses an EIA format. If the sample is reactive with two of three or three of three antigens, it is confirmed as seroreactive. If none or one of three beads is reactive, the sample is indeterminate and subjected to a radioimmunoprecipitation assay (RIPA). The RIPA must demonstrate characteristic bands at 32, 34, and 90 kDa. RESULTS: When tested with sera from persons with potentially cross-reactive diseases (n = 39) or against a presumed negative population from southeast Wisconsin (n = 289), the confirmatory EIA had a specificity of 100 percent. Sensitivity was 100 percent (28/28) with xenodiagnosis-positive sera and 97.6 percent (80/82) with chagasic sera from Latin America. The RIPA showed a specificity of 100 percent in EIA- nonreactive samples (n = 100) and a sensitivity of 100 percent with both xenodiagnosis-positive (28/28) and chagasic (82/82) sera. CONCLUSION: The confirmatory EIA and the RIPA together provide a highly specific and sensitive means of confirming seroreactivity for antibodies to T. cruzi.  相似文献   
105.
106.
Aim:  This trial evaluated the potential for improving glycaemic control by intensifying a conventional twice-daily therapy with premixed human insulin (HI) to a thrice-daily regimen using premixed formulations of biphasic insulin aspart (BIAsp) in patients with type 1 or type 2 diabetes.
Methods:  This was a multicentre, open-label, parallel group trial. After a 4-week run-in period, patients were randomized 1 : 1 to 16 weeks of treatment. A total of 748 patients were screened, 664 were exposed to trial drug and 604 completed the trial.
Results:  Haemoglobin A1c, the primary efficacy endpoint, was shown to be significantly lower for the BIAsp treatment group compared with the biphasic HI (BHI) 30 group [estimated mean difference: −0.32, 95% confidence interval (CI) (−0.48; −0.16), p = 0.0001]. The average blood glucose level was significantly lower in the BIAsp group [estimated mean difference: −0.79, 95% CI (−1.17; −0.40), p = 0.0001]. There were few major hypoglycaemic episodes, 11 in the BIAsp group and 7 in the BHI 30 group. Although intensification of insulin therapy with BIAsp three times a day was associated with a higher risk of minor hypoglycaemia (relative risk = 1.58, p = 0.0038), the overall rate of minor hypoglycaemia remained low with both the BIAsp and the BHI treatments (13.1 vs. 8.3 episodes/patient year respectively). Overall safety and patient satisfaction were similar with the two insulin therapies.
Conclusions:  This trial confirmed that a thrice-daily BIAsp regimen can safely be used to intensify treatment for patients inadequately controlled on twice-daily BHI. A treat-to-target trial is required to explore the full potential of the BIAsp regimens and evaluate their use as a viable alternative to intensification with a basal-bolus regimen.  相似文献   
107.
This study demonstrates the excellent diagnostic accuracy of the Xpert MTB/RIF test in patients with tuberculous lymphadenitis. The test sensitivity and specificity were 96.7% (95% confidence interval [CI], 86.6 to 100%) and 88.9% (95% CI, 69.6 to 100%), respectively, and it correctly identified 6/6 (100%) of the cytology smear-negative/culture-positive cases and 1 of 2 (50%) rifampin-resistant cases.  相似文献   
108.
OBJECTIVE: To determine for what reasons West African immigrants, who contribute the largest single group of malaria cases in the Netherlands, visit pre-travel preventive health services and whether use of such services is likely to improve use of preventive measures. METHODS: Semi-structured interviews with eligible participants recruited through West African churches and societies and at a large festival. RESULTS: A total of 70% of the total non-random sample of 292 participants said that they always use pre-travel preventive health services before travelling. Being from Ghana (OR = 2.5), having legal residency status (OR = 2.5), visiting friends and relatives rather than going for business or funeral (OR = 6.7), and living in Amsterdam (OR = 5.1) were all independently associated with using pre-travel preventive health services, as were taking general preventive measures (OR = 3.0), and self-reported use of malaria prophylaxis. Higher use of pre-travel preventive health services was not associated with better knowledge of malaria as such. CONCLUSIONS: West Africans, in particular non-Ghanaians, illegal immigrants and West African immigrants leaving at short notice should be encouraged to use pre-travel preventive health services. Adequate methods to reach these groups need to be developed, including health education on the importance of prevention in general.  相似文献   
109.
We measured red blood cell iron incorporation (RBC-inc) in 13 human milk-fed premature infants (birthweight 1037 +/- 289 g, gestational age 27 +/- 2 wk, weight at start of study 1571 +/- 426 g) who were receiving full tube-feedings of human milk fortified with a commercial human milk fortifier (FortHM). The relative RBC-inc of supplemental iron (2 mg/kg/d of ferrous sulfate) was assessed using 57Fe sulfate mixed directly into a 24-h volume of FortHM, and 54Fe sulfate given as a bolus between two FortHM feedings the next day. RBC-inc was similar between the two methods of supplemental iron administration (4.7 +/- 2.5% vs 4.6 +/- 1.5%, respectively). Although these values are lower than RBC-inc expected from iron native to human milk, the relatively large amount of iron in the supplements contributed most of the iron incorporated into RBC by the infants. There was a significant positive correlation between the reticulocyte count and RBC-inc. As the high nutrient (especially calcium) content of the FortHM did not interfere with iron utilization, adding iron directly to FortHM, or incorporating it into commercial fortifiers, may be a practical method to provide iron to premature infants.  相似文献   
110.
Objectives: To assess the influence of clinical status on the association between total plasma bilirubin and unbound bilirubin on death or adverse neurodevelopmental outcomes at 18–22 months corrected age in extremely low birth weight infants. Method: Total plasma bilirubin and unbound bilirubin were measured in 1101 extremely low birth weight infants at 5 ± 1 days of age. Clinical criteria were used to classify infants as clinically stable or unstable. Survivors were examined at 18–22 months corrected age by certified examiners. Outcome variables were death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death prior to follow‐up. For all outcomes, the interaction between bilirubin variables and clinical status was assessed in logistic regression analyses adjusted for multiple risk factors. Results: Regardless of clinical status, an increasing level of unbound bilirubin was associated with higher rates of death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss and death before follow‐up. Total plasma bilirubin values were directly associated with death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death before follow‐up in unstable infants, but not in stable infants. An inverse association between total plasma bilirubin and death or cerebral palsy was found in stable infants. Conclusions: In extremely low birth weight infants, clinical status at 5 days of age affects the association between total plasma bilirubin and death or adverse neurodevelopmental outcomes at 18–22 months of corrected age. An increasing level of UB is associated a higher risk of death or adverse neurodevelopmental outcomes regardless of clinical status. Increasing levels of total plasma bilirubin are directly associated with increasing risk of death or adverse neurodevelopmental outcomes in unstable, but not in stable infants.  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