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   7282篇
  免费   603篇
  国内免费   8篇
耳鼻咽喉   89篇
儿科学   219篇
妇产科学   197篇
基础医学   944篇
口腔科学   117篇
临床医学   842篇
内科学   1500篇
皮肤病学   48篇
神经病学   751篇
特种医学   172篇
外科学   833篇
综合类   153篇
一般理论   15篇
预防医学   947篇
眼科学   137篇
药学   556篇
中国医学   3篇
肿瘤学   370篇
  2023年   70篇
  2022年   131篇
  2021年   229篇
  2020年   154篇
  2019年   223篇
  2018年   250篇
  2017年   188篇
  2016年   202篇
  2015年   209篇
  2014年   306篇
  2013年   441篇
  2012年   551篇
  2011年   554篇
  2010年   257篇
  2009年   234篇
  2008年   377篇
  2007年   366篇
  2006年   343篇
  2005年   333篇
  2004年   246篇
  2003年   275篇
  2002年   239篇
  2001年   120篇
  2000年   95篇
  1999年   115篇
  1998年   81篇
  1997年   44篇
  1996年   55篇
  1995年   58篇
  1994年   54篇
  1993年   35篇
  1992年   68篇
  1991年   72篇
  1990年   51篇
  1989年   68篇
  1988年   55篇
  1987年   57篇
  1986年   51篇
  1985年   36篇
  1984年   38篇
  1983年   33篇
  1982年   30篇
  1981年   28篇
  1979年   33篇
  1978年   32篇
  1976年   32篇
  1974年   30篇
  1972年   33篇
  1970年   25篇
  1967年   30篇
排序方式: 共有7893条查询结果,搜索用时 15 毫秒
51.
Diabetes mellitus in Huntington disease   总被引:8,自引:0,他引:8  
There have been conflicting reports that individuals with Huntington disease (HD) are prone to abnormalities of carbohydrate metabolism. In this study information about the incidence and control of diabetes mellitus in 620 probands (278 living, 332 deceased) with HD and in their first and second degree relatives was obtained by questionnaire method from participants of the National HD Research Roster. Among the probands, 65 individuals (10.5%) were identified by the informant or verified by examination of Roster family records as diabetic. The prevalence of diabetes, particularly among those less than 50 years of age, is significantly greater than corresponding figures among the general U.S. Caucasian population (Scott 1977, Krolewski & Warram 1985). Incidence rates were not calculated because of ascertainment and other biases in the data. Results from the analysis of family data indicate that HD affected relatives of an HD proband with diabetes are 7 times as likely to have diabetes over the proband's non-HD relatives. A non-diabetic HD proband is equally likely to have an HD or non-HD relative with diabetes.  相似文献   
52.
BACKGROUND: The aim of the European Sero-Epidemiology Network (ESEN2) is to harmonise the serological surveillance of vaccine-preventable diseases in Europe. OBJECTIVE: To allow comparison of antibody prevalence in different countries by standardising results into common units. STUDY DESIGN: For varicella zoster virus (VZV), a reference laboratory established a panel of 148 samples, characterised by indirect enzyme-immunoassay (ELISA), indirect immunofluorescence, and complement fixation test. Fifty-seven samples were also studied by the fluorescence antibody to membrane antigen test. The geometric mean of the antibody activity (GMAA) obtained from four ELISA determinations was used to characterise each sample of the panel as positive (GMAA: >100 mIU/ml), equivocal (GMAA: 50-100 mIU/ml) or negative (GMAA: <50 mIU/ml) for antibody to VZV (anti-VZV). Thirteen laboratories, using five different ELISA tests, tested the panel. RESULTS: Agreement with the reference laboratory was above 85% in all cases, and the R(2) values obtained from regression analysis of the quantitative results were always higher than 0.87. Finally, the regression equations could be used to convert national values into a common unitage. CONCLUSION: This study confirmed that results for anti-VZV obtained by different ELISA methods can be converted into common units, enabling the comparison of the seroprevalence profiles obtained in the participant countries.  相似文献   
53.
54.
A number of metabolites of 17beta-estradiol were tested for their estrogenic activity using the ER-CA-LUX assay based on the increased expression of luciferase in exposed T47D breast cancer cells. E2beta and estrone showed similar potencies in the test, whereas E2alpha was 100 times less active. Incubation of cells with estrone (0.35 microM) resulted in the formation of E2beta, whereas the reverse reaction was observed for E2beta. The resulting equilibrium may explain the similar estrogenic potency of estrone in the test. The synthetic 17-hydroxy benzoate ester of E2beta was 3 times less active than the parent compound. The 17-hydroxy palmitate and oleate esters of E2beta, were respectively 25 and 200 times less active than the parent compound. The 2-hydroxy metabolites of E2beta and estrone showed a 5,000 to 10,000 fold lower activity. The 4-hydroxy metabolites were more potent than the 2-hydroxy metabolites, showing only a 20-200 times lower activity. The 2- and 4-methoxyesters of estrone were 700 times less active. It is concluded that the estrogenic potency of metabolites formed in cattle after treatment with E2beta, like estrone, E2alpha and especially the esters of E2beta, may be significant with respect to the potential risk of the use of estradiol for growth promotion in domestic animals in certain countries.  相似文献   
55.
The influence of the presence of the male on the ovulation process was investigated in ewes after oestrus control by progestagens (intravaginal fluorogestone acetate) and PMSG. Permanent contact with the rams throughout oestrus accelerates the ovulation and the appearance of the LH surge. The results suggest that the action of the presence of the male on ovulation is mediated by way of the ovulatory surge of LH.  相似文献   
56.
57.
We set out to test the hypothesis that home blood pressure reflects "baseline" pressures measured at a general practitioner's surgery or in a hospital outpatient clinic. Twenty patients detected hypertensive during screening in general practice and 30 patients referred to a hospital hypertension clinic for revision of therapy were studied. All were instructed in the use of an electronic semiautomatic sphygmomanometer and measured blood pressure at home for a three day period. Home monitored blood pressure correctly predicted those patients whose diastolic blood pressure fell to below 95 mmHg by the third clinic visit in approximately 90% of all patients. In addition, in those whose blood pressure was high at home it remained so at the clinic or surgery after three visits. These data suggest that home monitoring of blood pressure may be a helpful alternative to repeated clinic visits before embarking on medical therapy.  相似文献   
58.
ObjectivesTo report the initial compliance with new infection control regulations and geographic disparities in nursing homes (NHs) in the United States.DesignRetrospective cohort study from November 27, 2017 to November 27, 2019.Setting and ParticipantsIn total, 14,894 NHs in the continental United States comprising 26,201 inspections and 176,841 deficiencies.MethodsWe measured the cumulative incidence of receiving F880: Infection Prevention and Control deficiencies, geographic variability of F880 citations across the United States, and the scope and severity of the infection control deficiencies.ResultsA total of 6164 NHs (41%) in the continental United States received 1 deficiency for F880, and 2300 NHs (15%) were cited more than once during the 2-year period. Geographic variation was evident for F880 deficiencies, ranging from 20% of NHs in North Carolina to 79% of NHs in West Virginia. Between 0% (Vermont) and 33% (Michigan) of states’ NHs were cited multiple times over 2 years. Facilities receiving 2 or more F880 deficiencies were more reliant on Medicaid, for-profit, and served more acute residents. Infection Prevention and Control deficiencies were of similar severity but of greater scope in NHs that were cited multiple times.Conclusions and ImplicationsAs the coronavirus disease 2019 pandemic challenges hospitals with an increased surge of patients from the community, NHs will be asked to accept convalescing patients who were previously infected with the virus. NHs will need to rely on infection control practices to mitigate the effects of the virus in their facilities. Particular attention to NHs that have fared poorly with repeat infection control practices deficiencies might be a good first step to improving care overall and preventing downstream morbidity and mortality among the highest-risk patients.  相似文献   
59.
PurposeExploring the impact of the COVID-19 pandemic on young people’s mental health is an increasing priority. Studies to date are largely surveys and lack meaningful involvement from service users in their design, planning, and delivery. The study aimed to examine the mental health status and coping strategies of young people during the first UK COVID-19 lockdown using coproduction methodology.MethodsThe mental health status of young people (aged 16–24) in April 2020 was established utilizing a sequential explanatory coproduced mixed methods design. Factors associated with poor mental health status, including coping strategies, were also examined using an online survey and semi-structured interviews.ResultsSince the lockdown, 30.3% had poor mental health, and 10.8% had self-harmed. Young people identifying as Black/Black-British ethnicity had the highest increased odds of experiencing poor mental health (odds ratio [OR] 3.688, 95% CI .54–25.40). Behavioral disengagement (OR 1.462, 95% CI 1.22–1.76), self-blame (OR 1.307 95% CI 1.10–1.55), and substance use (OR 1.211 95% CI 1.02–1.44) coping strategies, negative affect (OR 1.109, 95% CI 1.07–1.15), sleep problems (OR .915 95% CI .88–.95) and conscientiousness personality trait (OR .819 95% CI .69–.98) were significantly associated with poor mental health. Three qualitative themes were identified: (1) pre-existing/developed helpful coping strategies employed, (2) mental health difficulties worsened, and (3) mental health and nonmental health support needed during and after lockdown.ConclusionPoor mental health is associated with dysfunctional coping strategies. Innovative coping strategies can help other young people cope during and after lockdowns, with digital and school promotion and application.  相似文献   
60.
The coronavirus disease pandemic has highlighted the key role epidemiologic models play in supporting public health decision-making. In particular, these models provide estimates of outbreak potential when data are scarce and decision-making is critical and urgent. We document the integrated modeling response used in the US state of Utah early in the coronavirus disease pandemic, which brought together a diverse set of technical experts and public health and healthcare officials and led to an evidence-based response to the pandemic. We describe how we adapted a standard epidemiologic model; harmonized the outputs across modeling groups; and maintained a constant dialogue with policymakers at multiple levels of government to produce timely, evidence-based, and coordinated public health recommendations and interventions during the first wave of the pandemic. This framework continues to support the state’s response to ongoing outbreaks and can be applied in other settings to address unique public health challenges.  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