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   1008篇
  免费   68篇
  国内免费   16篇
耳鼻咽喉   30篇
儿科学   94篇
妇产科学   9篇
基础医学   105篇
口腔科学   15篇
临床医学   94篇
内科学   200篇
皮肤病学   23篇
神经病学   37篇
特种医学   124篇
外科学   80篇
综合类   120篇
预防医学   68篇
眼科学   4篇
药学   41篇
中国医学   2篇
肿瘤学   46篇
  2023年   3篇
  2022年   6篇
  2021年   22篇
  2020年   3篇
  2019年   8篇
  2018年   12篇
  2017年   12篇
  2016年   14篇
  2015年   25篇
  2014年   35篇
  2013年   25篇
  2012年   56篇
  2011年   45篇
  2010年   45篇
  2009年   42篇
  2008年   59篇
  2007年   52篇
  2006年   36篇
  2005年   29篇
  2004年   32篇
  2003年   29篇
  2002年   28篇
  2001年   28篇
  2000年   24篇
  1999年   28篇
  1998年   48篇
  1997年   44篇
  1996年   34篇
  1995年   21篇
  1994年   28篇
  1993年   24篇
  1992年   12篇
  1991年   13篇
  1990年   10篇
  1989年   17篇
  1988年   16篇
  1987年   32篇
  1986年   14篇
  1985年   13篇
  1984年   5篇
  1983年   8篇
  1982年   14篇
  1981年   5篇
  1980年   6篇
  1979年   1篇
  1978年   8篇
  1977年   5篇
  1976年   9篇
  1975年   6篇
  1967年   1篇
排序方式: 共有1092条查询结果,搜索用时 31 毫秒
81.

Background

The United States is implementing plans to immunize 500,000 hospital-based healthcare workers against smallpox. Vaccination is voluntary, and it is unknown what factors drive vaccine acceptance. This study's aims were to estimate the proportion of workers willing to accept vaccination and to identify factors likely to influence their decisions.

Methods

The survey was conducted among physicians, nurses, and others working primarily in emergency departments or intensive care units at 21 acute-care hospitals in 10 states during the two weeks before the U.S. national immunization program for healthcare workers was announced in December 2002. Of the questionnaires distributed, 1,165 were returned, for a response rate of 81%. The data were analyzed by logistic regression and were adjusted for clustering within hospital and for different number of responses per hospital, using generalized linear mixed models and SAS's NLMIXED procedure.

Results

Sixty-one percent of respondents said they would definitely or probably be vaccinated, while 39% were undecided or inclined against it. Fifty-three percent rated the risk of a bioterrorist attack using smallpox in the United States in the next two years as either intermediate or high. Forty-seven percent did not feel well-informed about the risks and benefits of vaccination. Principal concerns were adverse reactions and the risk of transmitting vaccinia. In multivariate analysis, four variables were associated with willingness to be vaccinated: perceived risk of an attack, self-assessed knowledge about smallpox vaccination, self-assessed previous smallpox vaccination status, and gender.

Conclusions

The success of smallpox vaccination efforts will ultimately depend on the relative weight in people's minds of the risk of vaccine adverse events compared with the risk of being exposed to the disease. Although more than half of the respondents thought the likelihood of a bioterrorist smallpox attack was intermediate or high, less than 10% of the group slated for vaccination has actually accepted it at this time. Unless new information about the threat of a smallpox attack becomes available, healthcare workers' perceptions of the vaccine's risks will likely continue to drive their ongoing decisions about smallpox vaccination.
  相似文献   
82.
83.
OBJECTIVE: To generate estimates of sinusitis prevalence for adults in association with the use of tobacco or passive smoke exposure. DESIGN: Analysis of data from the Third National Health and Nutrition Examination Survey, 1988-1994. SETTING: Sample of the noninstitutionalized civilian population of the United States. PARTICIPANTS: A total of 20,050 adults aged 17 years or older. MAIN OUTCOME MEASURE: Presence of self-reported sinusitis or sinus problems. RESULTS: In the United States, 66 million adults, constituting 35% of the adult population, reported having sinusitis or sinus problems at least once during the previous 12 months. Female sex, non-Hispanic white or non-Hispanic black race, higher income levels, and progressively higher educational levels were associated with increased prevalence of sinusitis. The prevalence of both acute and recurrent or chronic sinusitis increased with direct cigarette and other tobacco use but did not rise with passive exposure to cigarette smoke. CONCLUSIONS: Consistent with data for other respiratory ailments, the direct use of tobacco confers a small increased risk of developing sinusitis in the adult population, but contrary to expectation, passive smoke does not. The demographic variables of sex, race/ethnicity, and educational level demonstrated unexpectedly strong associations with the prevalence of sinusitis and should be analyzed and controlled for in future studies of sinusitis.  相似文献   
84.
Informed Consent     
There have been significant changes in the doctor patient relationship with the impact of technology in day-to-day practice. More and more patients are aware of their rights and are keen to make free choice and decision on their treatment. This helps them to choose the treatment of their choice from the options available and to select a physician of their choice. Doctor's decisions are being questioned regarding their correctness and there is a need to educate the patient, on what one offers by way of treatment. In some procedures and types of treatment, patient needs to be educated and informed of the merits and demerits of the treatment available. This will help the patient to make appropriate choice and also to accept some adverse outcome of treatment. Towards this end, all countries are looking afresh at the necessity of Informed Consent. Methods adopted by some countries are highlighted to help our physicians practice them in an appropriate way. A lot of remedial work needs to be done to minimize future litigation, as many doctors misunderstand their legal obligations and haven't caught up with the change in judge's thinking.  相似文献   
85.
The significance of a subcentimetre 18F-FDG PET/CT pulmonary abnormality in a patient with known extrapulmonary primary malignancy can have a major impact on the clinical management of the patient. The clinician’s reliance on the semi-quantitative and qualitative PET/CT analysis of the abnormality has, at times, led to untoward diagnostic problems, given the limited spatial resolution of PET for a small volume lesion performed as part of the standard PET/CT study. This paper highlights a case each of an FDG-positive and an FDG-negative focal pulmonary abnormality in a combined PET/CT study of patients with known extrapulmonary malignancy. © 2010 Biomedical Imaging and Intervention Journal. All rights reserved.  相似文献   
86.
87.
Jaundice persisting beyond the first 2 wk of life is often regarded as an indication for investigation to exclude cholestatic liver disease. Most babies with prolonged jaundice have breast milk-related jaundice, which is a benign condition. Cholestatic liver disease is usually accompanied by pale stools and yellow or orange urine. A community programme was established to ascertain the incidence of prolonged jaundice and determine whether abnormal stool and urine colour could be used to assist primary care staff in referral decisions. Data were collected on normal stool and urine colour and used to devise a colour chart and information sheet for parents. Babies with prolonged jaundice were identified and referred for investigation. In all, 3661 babies were recruited into the study, of which 127 were jaundiced at 28 d of age. Of these, 125 were breastfed. The incidence of jaundice in breastfed babies at 28 d was 9.2% (95% CI 7.8%-11.0%) Abnormal liver function tests (LFTs) were common, but no baby had abnormal stool or urine colour and none was found to have liver disease. Jaundiced breastfed babies who are well are unlikely to have serious disease. Elevated LFTs are compatible with a diagnosis of breast milk-related jaundice. Prolonged jaundice in bottle-fed babies, and persistent pallor of stools or yellow/orange urine, are rare and merit immediate referral. Parents and professionals can be advised to report pale stools without generating a large number of unnecessary referrals. Further work is needed to determine whether a colour chart reduces the mean age of referral and treatment of infants with cholestatic liver disease.  相似文献   
88.
By using five Taiwan Macaca monkeys as experimental animals, three bony defects about 5 x 5 x 3 mm in size were created at each of their buccal region of mandible. Bovine skin collagen and particulate hydroxylapatite were used as implant materials. The artificial defects implanted with hydroxylapatite/collagen mixture were experimental group and the defects implanted with collagen or without any implantation were control groups. The monkeys were sacrificed at the time of 1,2,3,6,9 months after implantation surgery and were injected with tetracycline according to the above intervals at one week before being sacrificed. The specimens were divided into two parts, one of which was decalcified and stained with hemotoxylineeiosin for observation under optic light microscope, the other without decalcification was made into ground section for observation under fluorescent microscope. The result revealed that the healing processes of the two control groups were similar with each other. Bone formation was delayed in HA/Collagen group because it took almost five months to achieve complete bony repair of the mandibular defect. However bone formation at the HA/Collagen implant site was earlier than that at the pure HA implant site in our similar study. What's the role of collagen that played during bone formation still needed further investigation. The tissue response was good without obvious inflammatory cells infiltration. Clinical application of block form of dried HA/Collagen mixture was suggested for it was easier to handle and could decrease the flow of HA particles after implantation.  相似文献   
89.
In vitro neuronal differentiation of Drosophila embryo cells   总被引:5,自引:0,他引:5  
Early gastrula-stage Drosophila embryo cells will differentiate in vitro to form several cell types, including neurons. We report here the morphological appearance of cultured embryo cells, the pattern of DNA synthesis, and the expression of neurotransmitter-metabolizing macromolecules. The cells initially exhibit no overt morphological differentiation, and all cells incorporate 3H-thymidine following a 1 hr pulse-labeling period. As cells undergo morphological differentiation, fewer total cells as well as qualitatively different cell types incorporate label. By the time cells are 8 or 9 hr old, no myocytes or myotubes are labeled. In contrast, some neurons are labeled with a thymidine pulse as late as 18 hr. We have also stained cultured cells of various developmental ages with the insect neuron-specific antibody: anti-HRP. Some positive cells can be detected as early as 5 hr, when no overt morphological differentiation is apparent. As the cells differentiate, the staining is limited to the small, round neuronal type and its processes. These findings suggest that this neuron-specific cell marker is expressed very early in cultured gastrula-stage cells and may be used to identify neuronal precursor cells. We have studied the patterns of expression of several macromolecules involved in acetylcholine metabolism using these cultures. The appearance of choline acetyltransferase (ChAT), the biosynthetic enzyme for ACh production, is first detected in 5-hr-old cells. There is an initial phase of low-level expression, followed by a rapid rise in activity shortly after the differentiating neuron clusters make contact with one another. ChAT activity reaches a plateau in 36-48-hr-old cells. Acetylcholinesterase activity can be detected several hours before ChAT and also shows a period of low-level expression followed by a rapidly increasing phase, reaching a plateau at around 36-48 hr. 125I-alpha-bungarotoxin binding appears in cells about 4 hr old and rapidly approaches maximum levels by about 36 hr. The in vitro expression pattern for ChAT and AChE is similar to that seen in vivo. AChE activity has been localized histochemically to the neurons and their processes in vitro. The normal in vitro expression pattern for ChAT and AChE can be altered by adding various cholinergic drugs to the culture medium during cell differentiation. Medium conditioned by older cultures can also result in lower levels of ChAT and AChE expression.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
90.
The aim of the study was to assess the prevalence of headache with special attention to tension-type headache (TTH) in a rural area in northern Tanzania. A door-to-door study was performed using a standardized and validated questionnaire. A total of 7412 participants were screened. The total headache prevalence during the past year was 12.1%; the overall 1-year prevalence of TTH was 7%; 5% reported episodic TTH and 0.4% chronic TTH. Borderline cases (International Headache Society code 2.3) were described in 1.6%. The prevalence of headache was highest in the 41–50-year-old group in women and in the 61+ age group in men. This is the first account of the prevalence of TTH in a rural Tanzanian population, and shows that headache in general and, more specifically, TTH are prevalent disorders that deserve attention. However, the prevalence of primary headache seems to be lower than in Western countries.  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