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   1776篇
  免费   131篇
  国内免费   5篇
耳鼻咽喉   10篇
儿科学   63篇
妇产科学   56篇
基础医学   196篇
口腔科学   20篇
临床医学   353篇
内科学   295篇
皮肤病学   23篇
神经病学   169篇
特种医学   31篇
外科学   160篇
综合类   16篇
一般理论   5篇
预防医学   260篇
眼科学   12篇
药学   112篇
中国医学   5篇
肿瘤学   126篇
  2023年   18篇
  2022年   29篇
  2021年   40篇
  2020年   30篇
  2019年   50篇
  2018年   53篇
  2017年   47篇
  2016年   48篇
  2015年   39篇
  2014年   75篇
  2013年   114篇
  2012年   115篇
  2011年   136篇
  2010年   83篇
  2009年   73篇
  2008年   110篇
  2007年   123篇
  2006年   105篇
  2005年   110篇
  2004年   96篇
  2003年   74篇
  2002年   85篇
  2001年   13篇
  2000年   10篇
  1999年   24篇
  1998年   32篇
  1997年   17篇
  1996年   10篇
  1995年   9篇
  1994年   13篇
  1993年   11篇
  1992年   9篇
  1991年   7篇
  1990年   5篇
  1989年   11篇
  1987年   8篇
  1985年   4篇
  1984年   4篇
  1983年   5篇
  1981年   4篇
  1980年   5篇
  1979年   5篇
  1978年   5篇
  1977年   5篇
  1975年   3篇
  1974年   3篇
  1972年   3篇
  1971年   6篇
  1969年   3篇
  1964年   3篇
排序方式: 共有1912条查询结果,搜索用时 41 毫秒
11.
Human populations have lived at high altitudes for lengths of time which are likely to be shortest in Colorado, intermediate in Peru, and longest in Tibet. We hypothesized that the longest-resident high-altitude populations have beccome better adapted than shorter-resident groups as a result of superior abilities to transport and/or utilize O2. Because birth weights are reduced at high altitude and decreased birth weight is associated with increased infant mortality, our criterion for assessing adaptation was preservation of birth weights close to values associated with the lowest mortality risk. Colorado (3,100 m) and Peru (4,300 m) birth weights averaged 3,186±70 g and 2,920±90 g respectively. A sample of 15 births from Tibet (3,658 m) weighed 3,307±110 g which was more than their altitude counterparts and close to sea-level norms. Pregnancy increased maternal ventilation at all three study sites. In Peru, the resultant elevation in arterial O2 saturation offset the pregnancy-induced fall in hemoglobin concentration to preserve arterial O2 content at nonpregnant levels. Arterial O2 content decreased slightly in Colorado and more markedly in Tibet in the pregnant compared to the nonpregnant state. The Colorado and Peru women with the greatest rise in ventilation and ventilatory sensitivity to hypoxia produced the heaviest birthweight infants, suggesting that maternal arterial oxygenation was an important determinant of fetal growth. The pregnant women in Tibet did not have higher levels of arterial O2 content than the pregnant Colorado or Peru women nor did maternal arterial O2 content relate to birth weight in Tibet. Infant birth weight in Tibet tended to be correlated with the ratio of uterine artery to common iliac artery mean flow velocity, suggesting that redistribution of lower-extremity blood flow to favor the uterine circulation may have acted to augment uterine O2 delivery in the Tibet women. Thus, the limited data available suggested that the Tibetans may be better adapted as judged by less fetal growth retardation and may utilize maternal O2 transport mechanisms not reliant upon increased arterial O2 content.  相似文献   
12.
Therapist affirmation was examined in two studies, the first with cognitive-behavioral therapy (CBT, N = 22) and the second with time-limited dynamic psychotherapy (TLDP, N = 20). Affirmation was identified using Structural Analysis of Social Behavior (SASB), and sequential analysis used to gauge its impact on therapy process and outcome. It was hypothesized that affirmation would correspond with patients' continuation of the current topic of conversation, but relate negatively to outcome if generally offered after maladaptive statements. Patients in Study 1 (CBT) were more likely to continue a topic after it was affirmed, and affirmation of maladaptive statements reliably differentiated patients who evidenced clinically significant change from those who did not at termination and at 12-months posttreatment. Affirmation of maladaptive statements in Study 2 (TLDP) corresponded with poorer outcome in relationships with significant others, but unexpectedly with improvements in self-concept.  相似文献   
13.
MethodsData on patients aged ≤19 years with a positive SARS-CoV-2 PCR test recorded in the period March 12-May 12 (first wave) and June 19-July 19, 2020 (second wave) were retrospectively analyzed. The periods were separated by several weeks with no incident cases.ResultsWe analyzed data on 289 children and adolescents (6.5% of all cases; incidence rate [IR] = 3.54, 95% confidence interval [CI] 3.14-3.97/million person-days), 124 in the first wave (IR = 2.27) and 165 in the second wave (IR = 6.37): IRR second/first = 2.71 (2.13-3.44). During the first wave, the incidence was highest in infants (IR = 3.48), while during the second wave it progressively increased to IR = 7.37 in 15-19-year olds. Family members were the key epidemiological contacts (72.6% cases), particularly during the first wave (95.8% vs 56.3%). Overall, 41.3% patients were asymptomatic, 25.3% in the first and 52.6% in the second wave. Age 15-19 years (vs younger) was associated with a higher (RR = 1.26, 1.02-1.54) and infection in the second wave with a lower probability (RR = 0.66, 0.53-0.81) of being symptomatic. The most common symptoms were fever, cough, and rhinorrhea. In children aged ≥7 years, headache, anosmia/ageusia, and sore throat were also recorded. Only one child suffered a severe disease. All but 18 (7.8%) children were treated only symptomatically, and all fully recovered.ConclusionA large proportion of SARS-CoV-2 PCR-positive children/adolescents were asymptomatic. The associated disease was predominantly mild, comparably so in the first and second pandemic wave.

Since the late December 2019, coronavirus disease 2019 (COVID-19) caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread quickly worldwide and as of early December accounts for more than 65 million cases diagnosed in more than 200 countries (1). At this point, the most affected countries in Europe are Russia, Spain, France, United Kingdom (UK), and Italy with consequently the highest mortality rates. The first case in Croatia was reported in the late February 2020, and within the next two months the infection expanded nationwide. During this first epidemic wave, Croatia was under a one-month lockdown, which rapidly decreased the disease incidence, and only a few newly diagnosed cases were reported between May 25 and June18, 2020. Easing of restrictions increased the incidence in late June, causing a second wave of COVID-19 in Croatia, with >147 000 cases reported so far (1,2).Over the last two decades, there were two other coronavirus outbreaks. Severe acute respiratory syndrome coronavirus appeared in 2002, affecting around 8000 people, with 10% mortality. Children (4 months-17 years) accounted for <0.02% of total cases, and there was no reported death in this age group. During the outbreak of the Middle East respiratory syndrome coronavirus, around 2300 people were infected, and children (<19 years of age) were rarely affected as well (2% of total cases; 2 reported deaths) (3,4). COVID-19 has exhibited a similar epidemiological pattern. Although early reports from China, Italy, and the United States (US) suggested that children and adolescents accounted for only 1%-2% of the overall COVID-19 cases (5-7), later reports around the world indicated a higher proportions of pediatric cases, between 1%-8% (8-10). Children of all ages can be affected by SARS-CoV-2 infection, but in contrast to other respiratory viruses, they usually suffer a mild or asymptomatic infection. Compared with adults, severe infections and fatal outcomes in children are rare, and several immunopathological mechanisms could be responsible for such differences in disease severity (11). Although many studies have reviewed the features of adults with COVID-19, overall data regarding pediatric cases are scarce, and most of them are reports from China and the US, with only a few studies describing disease in children from European countries.We aimed to describe epidemiological and clinical features of children and adolescents with COVID-19 confirmed by the polymerase chain reaction (PCR) test for SARS-CoV-2 in Croatia and to assess potential differences between the first (March-May 2020) and second (on-going) pandemic wave (June-July 2020).  相似文献   
14.

Background  

An integrated sense of professionalism enables health professionals to draw on relevant knowledge in context and to apply a set of professional responsibilities and ethical principles in the midst of changing work environments [1, 2]. Inculcating professionalism is therefore a critical goal of health professional education. Two multi-professional courses for first year Health Science students at the University of Cape Town, South Africa aim to lay the foundation for becoming an integrated health professional [3]. In these courses a diagram depicting the domains of the integrated health professional is used to focus the content of small group experiential exercises towards an appreciation of professionalism. The diagram serves as an organising framework for conceptualising an emerging professional identity and for directing learning towards the domains of 'self as professional' [4, 5].  相似文献   
15.
16.
Direct-acting antiviral (DAA) therapy has transformed the management of human immunodeficiency virus (HIV) and hepatitis C (HCV) coinfected patients with advanced liver disease. STOP-Coinfection was a multicenter prospective and retrospective, open-label study using sofosbuvir-based DAA therapy to treat HIV/HCV-coinfected participants pre– or post–liver transplant (LT). Sixty-eight participants with end-stage liver disease (Child-Turcotte-Pugh score ≥7 and Model for End-Stage Liver Disease score 6–29) were enrolled, 26 had hepatocellular carcinoma. Forty-two participants were treated pre–LT and 26 post–LT. All participants completed therapy without need for dose reduction or transfusion; eight required two or more courses of therapy. Ninety-three percent achieved a sustained virologic response and DAA therapy was well tolerated. Despite HCV cure, 12 end-stage liver disease participants required subsequent LT, 7 for decompensated liver disease. Thirteen participants died, 10 with decompensated liver disease pre–LT and three post–LT. Overall, transplant free survival was 42.8% at 4 years and post–LT survival was 87.9% at 5 years. We conclude that sofosbuvir-based DAA therapy is safe and highly effective in HCV-HIV patients with decompensated liver disease and post–LT, with post–LT survival rates comparable to other indications. This removes one of the last barriers to liver transplantation in this challenging cohort of recipients.  相似文献   
17.
AimWith the aim of providing a foundation for evidence-based public health actions, as well as the more individualised clinical treatment of migraine in Slovenia, the objective of our study was to assess the association between poor self-rated health (PSRH) and migraine, adjusted for selected comorbidity and socioeconomic factors.MethodsThe survey, conducted between August and December 2014, involved included 6,262 adults aged 15 years and over. Binary logistic regression was used in univariate as well as multivariate analysis. Three multivariate models were defined: MODEL 1 (migraine and comorbidities related to the physical dimension of health); MODEL 2 (comorbidities related to the mental dimension of health); MODEL 3 (demographic and socioeconomic factors).ResultsIn univariate as well as all three multivariate models, the odds of PSRH were statistically significantly higher in migraine sufferers in comparison to non-sufferers (univariate model: ORmigraine=yes vs. migraine=no=2.22 (p<0.001); MODEL 1: ORmigraine=yes vs. migraine=no=2.27 (p<0.001); MODEL 2: ORmigraine=yes vs. migraine=no=1.51 (p=0.002); MODEL 3: ORmigraine=yes vs. migraine=no=1.56 (p=0.001)).ConclusionMigraine is an important PSRH-related factor. Comorbidities related to the physical dimension of health do not reduce the power of association between migraine and PRSH, while comorbidities related to the mental dimension reduce the power of association of migraine and other health conditions. The power of the association between migraine and PRSH is also independent of demographic/socioeconomic factors. We can also conclude that migraine seems to be a phenomenon that is in a bi-directional relationship with mental states (thus having an impact on PSRH) and is itself a stressor.  相似文献   
18.

Purpose

There is conflicting evidence as to whether the effect of mannitol on brain bulk arises from haemodynamic, rheologic, or osmotic mechanisms. If mannitol alters cerebral haemodynamics by inducing vasoconstriction, this change should be reflected in cerebral blood flow velocity (CBFV) in the middle cerebral artery (MCA). The purpose of this study was to evaluate the effect of mannitol on CBFV in children.

Methods

Children scheduled for intracranial surgery were enrolled. After a loading dose of 10 μg · kg?1 of fentanyl, general anaesthesia was maintained with fentanyl (3 μg · kg?1 · hr?1), 66% nitrous oxide, and isoflurane (0.2–0.5% inspired). Mean and systolic CBFV (Vm and Vs) and pulsatility index (PI) were recorded with a transcranial Doppler (TCD) directed at the M1 segment of the MCA. Mannitol was administered, 1 gm · kg?1 iv over 15 min. The osmolality (Osm), haematocrit (Hct), mean arterial pressure (MAP), heart rate (HR), and TCD variables were recorded before and 15, 30, 45, and 60 min after the mannitol infusion.

Results

Mannitol infusion resulted in an increase in Osm and decrease in Hct (P < 0.05). Heart rate, MAP and arterial carbon dioxide tensions did not change (P > 0.05) during the measuring period. The Vm did not vary from baseline. The Vs and P1 both increased briefly (P < 0.01 at 15 min and P < 0.05 at 30 min) after the mannitol, suggesting an increase in resistance distal to the MCA.

Conclusion

The time course of CBFV changes produced by mannitol corresponds with previous animal data concerning cerebrovascular tone. Our results suggest that mannitol briefly increases cerebrovascular resistance and thereby diminishes cerebral blood volume.  相似文献   
19.
PURPOSE: Women with breast cancer were provided with an audiotape of their primary adjuvant treatment consultation, and the following patient outcomes were measured at 12 weeks postconsultation: perceived degree of information provision, audiotape satisfaction and use, communication satisfaction with oncologist, mood state, and cancer-specific quality of life. PATIENTS AND METHODS: Participants included 628 women newly diagnosed with breast cancer and 40 oncologists from six cancer centers in Canada. The patients were block randomized to one of four consultation groups: standard care control, not audiotaped; audiotaped, no audiotape given; audiotaped, patient given audiotape; and audiotaped, patient offered choice of receiving audiotape or not. RESULTS: Patients receiving the consultation audiotape had significantly better recall of having discussed side effects of treatment than patients who did not receive the audiotape. Audiotape benefit was not significantly related to patient satisfaction with communication, mood state, or quality of life at 12 weeks postconsultation, and was not significantly affected by choice of receiving the audiotape. Patients rated the audiotape intervention positively, with an average score of 83.9 of 100. CONCLUSION: Audiotape provision benefits patients by facilitating their perception of being informed about treatment side effects, but does not significantly influence patient satisfaction with communication, mood state, or quality of life.  相似文献   
20.
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