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   1905160篇
  免费   137983篇
  国内免费   5342篇
耳鼻咽喉   24600篇
儿科学   62424篇
妇产科学   50666篇
基础医学   284655篇
口腔科学   53020篇
临床医学   180598篇
内科学   364749篇
皮肤病学   39699篇
神经病学   151208篇
特种医学   69316篇
外国民族医学   430篇
外科学   270194篇
综合类   41537篇
现状与发展   3篇
一般理论   603篇
预防医学   155849篇
眼科学   42654篇
药学   142156篇
  9篇
中国医学   5135篇
肿瘤学   108980篇
  2021年   15099篇
  2019年   15788篇
  2018年   22252篇
  2017年   16901篇
  2016年   18432篇
  2015年   21015篇
  2014年   28805篇
  2013年   44228篇
  2012年   60234篇
  2011年   63755篇
  2010年   37200篇
  2009年   34472篇
  2008年   58616篇
  2007年   62149篇
  2006年   62752篇
  2005年   60020篇
  2004年   57601篇
  2003年   54762篇
  2002年   53217篇
  2001年   89237篇
  2000年   91497篇
  1999年   76380篇
  1998年   21059篇
  1997年   18646篇
  1996年   18732篇
  1995年   17787篇
  1994年   16536篇
  1993年   15415篇
  1992年   60110篇
  1991年   58964篇
  1990年   57218篇
  1989年   55121篇
  1988年   50743篇
  1987年   49356篇
  1986年   47019篇
  1985年   44632篇
  1984年   33304篇
  1983年   28378篇
  1982年   16577篇
  1979年   30325篇
  1978年   21436篇
  1977年   17776篇
  1976年   17285篇
  1975年   18131篇
  1974年   21935篇
  1973年   21290篇
  1972年   19789篇
  1971年   18417篇
  1970年   17305篇
  1969年   15838篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
At this study a multi-criteria model was developed to examine the available procedures, techniques and methods of handling infectious waste in the large healthcare unit of University Regional General Hospital of Patras, Western Greece. Particularly, this study examined the: a) current legislation and Directives issued for medical waste management at Greece and among the other EU-members, b) contribution of healthcare wastes (HCW) generation rate on social and economic parameters in selected European countries, c) available procedures, techniques, and methods upon the disposal of infectious wastes at the healthcare studied, and, d) propositions for integrated management of such hazardous wastes. Specifically, the Analytic Hierarchy Process (AHP) methodology was applied under pair wise comparison matrices in two stages: 1) the scale factors and the indicators, and 2) the criteria and their sub–criteria. The assessment of these pair wise matrices included the indicators and the sub–criteria. Subsequently, two pair wise comparison matrices, upon a) the “Fulfillment of environmental objectives” indicator and b) the “Energy consumption” sub criterion, were denoted. The AHP methodology yielded good results; however there is still space of improving the environmental performance. The normalized relative weights obtained for the criteria and sub criteria motivated specific actions that have to be handled. Particularly, the results indicated a very good value in environmental management criteria due the values obtained for the commitment towards the environmental policy standards and the waste management procedures. However, further improvements on staff awareness (such as development programs to enhance sensitivity) and more green purchasing suppliers, should be further addressed.  相似文献   
102.
Few studies have examined the effects of parental incarceration (PI) on outcomes above and beyond other risk and adverse childhood experiences (ACEs). The objectives of this study were to (1) the associations between PI and mental health problems (attention, externalizing, internalizing, and total behavioral problems) and (2) the mediating role of current socioeconomic status and cumulative ACEs. An observational and cross-sectional design was employed. Analyses included hierarchical multivariable linear regression modeling. The analytic sample included 613 adolescents (11–17?years). On average, youth exposed to PI experienced three times as many ACEs compared with youth unexposed. Youth exposed to PI were more likely to have behavioral problems than their unexposed peers. The main effect for all models was attenuated by current economic hardship as well as exposure to increasing numbers of ACEs. Exposure to PI can be viewed as a marker of accumulative risk for intervention since youth impacted by PI are more likely to experience behavioral difficulties and associated adverse childhood experiences. Due to the associated adversity that impact youth exposed to PI, mental health providers need to be able to identify and screen for symptoms associated with trauma.  相似文献   
103.
Neuroscience and Behavioral Physiology - Objective. To determine the frequency, structure, and severity of cognitive impairments in patients with bipolar affective disorder (BAD) in remission....  相似文献   
104.
First described in 1955 in New Jersey, epizootic haemorrhagic disease (EHD) causes a severe clinical disease in wild and domestic ruminants worldwide. Epizootic haemorrhagic disease outbreaks occur in deer populations each year from summer to late autumn. The etiological agent is EHD virus (EHDV) which is a double‐stranded segmented icosahedral RNA virus. EHD virus utilizes point mutations and reassortment strategies to maintain viral fitness during infection. In 2018, EHDV serotype 2 was predominantly detected in deer in Illinois. Whole genome sequencing was conducted for two 2018 EHDV2 isolates (IL41747 and IL42218) and the sequence analyses indicated that IL42218 was a reassortant between different serotypes whereas IL41747 was a genetically stable strain. Our data suggest that multiple strains contribute to outbreaks each year.  相似文献   
105.
PurposeTo examine what proportion of caregivers, if given a choice, would choose medical versus surgical treatment of appendicitis and what factors would be important in their decision.MethodsA survey was devised and given to the caregivers of children presenting to the pediatrician for a routine visit in community and academic pediatric clinics. The survey presented a summary of outcomes after medical (non-operative) and surgical treatment of uncomplicated appendicitis. Participants were then asked to choose medical versus surgical treatment if their child were to develop appendicitis. They were also asked to rate the importance of certain factors in their decision ? 1 being “not important” and 5 being “very important”.ResultsFour hundred surveys were distributed with an 86.2% (345/400) response rate. Six percent (21/342) of respondents reported a history of appendicitis and 49.4% (168/340) reported having known someone who had appendicitis. The majority of respondents, 85.3% (284/333), were mothers. A minority of respondents, 41.7% (95% CI: 36.7, 47.0), chose medical treatment over surgery for appendicitis. There was no statistical difference in the proportion of mothers (41.6%) versus fathers who chose medical treatment (41.3%). Caregivers who chose medical treatment were more likely to rate time in hospital (p = .008) and time out of school (p = 05) as important in decision making when compared with those who chose surgery. Those who chose surgical treatment were more likely to rate risk of recurrent appendicitis (p < .001) as important to decision making. In the multivariate analysis, those who rated time in hospital as very important had more than twice the odds of choosing medical therapy (OR 2.20, p = 0.02) when compared with those who rated it as less important. Not knowing someone who has had appendicitis was significantly associated with choosing medical therapy when compared with those who do know someone who has had appendicitis, OR 2.3, p = .002. Rating pain as very important was also significantly associated with choosing medical therapy, when compared to those rating pain 1–3, OR 3.38, p = .03.ConclusionsIn this survey of caregivers of children presenting for routine care, 41.7% would choose medical, or non-operative, therapy for their children with acute appendicitis. The risk of recurrence, time in hospital, and time out of school, pain, and knowing someone who has had appendicitis were all important factors that families may consider when making a decision. These data may be useful for surgeons counseling patients on which treatment to pursue.  相似文献   
106.
Background: Egyptian street youth use substances including tobacco, illicit drugs, and pharmaceutical drugs. To understand the circumstances, including adverse childhood experiences, that place adolescents at risk for engaging in substance use, we conducted in-depth interviews among a sample of Egyptian street children. Methods: From youth residing at or attending Caritas, a non-profit organization, which provides shelter and education to street youth, seven girls and twelve boys, aged 12–18 years, participated in open-ended, in-depth interviews. Results: Eight out of the 19 participants reported family history (early exposure) to substance use; and seven of them were initiated by either a family member (sibling), friend or coworker. Most of the participants reported a history of conflict with or abuse (verbal or physical) by their parents or siblings, or stressful situations at home; they used substance(s) to alleviate their stress. Few attended school, and some were forced to work and help their family. Conclusions: Among Egyptian youth, adverse childhood experiences, such as poverty, child abuse, and family substance use, challenge somewhat susceptible youths and lead them to the path of substance use and addiction. Prevention intervention should be multifaceted, culturally adaptable, and primarily targeting the social environment during childhood.  相似文献   
107.
Donor site morbidity following radial forearm flap (RFF) harvest remains a controversial issue. The aim of this meta-analysis was to answer the question “Are the range of wrist movements (range of motion, ROM) and hand strength affected after RFF harvesting?” The PubMed, Embase, Scopus, and Cochrane Library electronic databases were systematically searched (to December 2019). Self-controlled studies evaluating hand biomechanics after RFF harvest were included. Weighted mean differences with 95% confidence intervals were calculated using the random-effects model. The outcome variables were ROM, forearm movements, grip, and pinch strengths. Thirteen studies involving a total of 335 patients were included. With the exception of grip strength and supination, which showed statistically significant reductions of about 2.40 kg and 2.86° (P < 0.05), all other ROM, forearm movements, and pinch strengths showed an insignificant difference when the operated hand was compared to the non-operated hand (P > 0.05). Regression analysis showed that the method of donor site closure and size of the donor site defect had an insignificant impact on hand biomechanics. This study confirms the lack of discernible biomechanical morbidity after RFF transfer. The minimal reduction in hand biomechanics after RFF is considered to be clinically negligible.  相似文献   
108.
Fibroepithelial polyps (FEPs) are common, benign intraoral lesions that tend to develop slowly at predictable sites, often in response to local irritation or trauma. Historical precedent often results in referral to oral and maxillofacial surgery (OMFS) departments for biopsy, often irrespective of symptoms, and histological assessment. OMFS and pathology services are struggling to cope with an increasing workload that will potentially lead to widespread delays to diagnosis and treatment. Over the past 20 years, clinical pathways and guidance have been developed to ensure that healthcare interventions, such as the removal of third molars, tonsils, skin tags, and benign moles, are evidence-based, have a net patient benefit, and ensure the best use of finite NHS resources. However, no such guidance exists for intraoral lesions and we regard this as an oversight. We analysed the removal of 682 FEPs over a seven-year period and report sensitivities of 92.4% for a “confirmed clinical suspicion of an FEP” and 99.7% for a “confirmed clinical suspicion of a benign diagnosis”. The incidence of non-benign disease was 0.3%. Primary care dentists should be able to diagnose and monitor FEPs and refer only if symptoms are serious or in high-risk patients or sites. Adopting this practice across the UK could free up to 1825 four-hour OMFS clinics, 405 hours of consultant histopathologists’ time, and recurring savings to the NHS estimated to be in the region of £620 000/annum. We believe that the removal of FEPs should be reclassified as an “intervention not normally funded”, and the time and resources put to better use treating patients with lesions of questionable pathology.  相似文献   
109.
Food-grade titanium dioxide (E171) is widely used as a food additive, and it is known that after oral consumption, E171 is translocated into the bloodstream reaching the highest titanium level at 6 h. E171 is accumulated in some organs triggering toxicity, but the effects on the blood parameters after oral consumption have been less studied. Recently, evidence shows that oral exposure to E171 induces behavioral signs of anxiety and depression. The relation between blood alterations and psychiatric disorders has been previously demonstrated. However, the oral exposure to E171 effects on alterations in blood parameters and effects linked to alterations in animal behavior has not been explored. In this short communication, we aimed to investigate the effects of E171 on specific blood parameters (hematocrit, hemoglobin, number of erythrocytes, and leukocytes) and anxiety and compulsive-like behavior in males and females orally exposed to ~5 mg/kg for 4 weeks. The results showed that E171 decreased hematocrit and hemoglobin in male but not in female mice while leukocyte and erythrocyte count remained unaltered. Oral consumption of E171 decreased the levels of anxiety-like behavior in females but not in male mice, while compulsive-like behavior was increased in both male and female mice.  相似文献   
110.
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