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   1622篇
  免费   89篇
  国内免费   33篇
耳鼻咽喉   26篇
儿科学   65篇
妇产科学   20篇
基础医学   154篇
口腔科学   27篇
临床医学   147篇
内科学   378篇
皮肤病学   111篇
神经病学   38篇
特种医学   217篇
外科学   180篇
综合类   42篇
预防医学   103篇
眼科学   6篇
药学   36篇
中国医学   3篇
肿瘤学   191篇
  2020年   11篇
  2019年   13篇
  2017年   15篇
  2016年   22篇
  2015年   30篇
  2014年   35篇
  2013年   82篇
  2012年   31篇
  2011年   37篇
  2010年   63篇
  2009年   68篇
  2008年   34篇
  2007年   48篇
  2006年   36篇
  2005年   54篇
  2004年   35篇
  2003年   32篇
  2002年   35篇
  2001年   40篇
  2000年   21篇
  1999年   31篇
  1998年   86篇
  1997年   75篇
  1996年   77篇
  1995年   50篇
  1994年   63篇
  1993年   51篇
  1992年   17篇
  1991年   24篇
  1990年   23篇
  1989年   43篇
  1988年   45篇
  1987年   32篇
  1986年   26篇
  1985年   28篇
  1984年   23篇
  1983年   12篇
  1982年   21篇
  1981年   19篇
  1980年   13篇
  1979年   19篇
  1978年   14篇
  1977年   16篇
  1976年   18篇
  1975年   15篇
  1974年   8篇
  1973年   18篇
  1972年   10篇
  1971年   11篇
  1970年   10篇
排序方式: 共有1744条查询结果,搜索用时 15 毫秒
71.
72.
Detection of multiple pathogens, particularly a combination of viruses and bacteria, is infrequently documented in outbreaks of gastroenteritis. This paper reports the presence of Norwalk-like virus (NLV) and enterohaemorrhagic verotoxin-producing Escherichia coli in one individual, and NLV and verotoxin-producing Aeromonas sobria in another individual, both part of a large gastroenteritis outbreak. The causes of gastroenteritis in such outbreaks may be more complex than previously thought.  相似文献   
73.
74.
Parent‐of‐origin–dependent (epi)genetic factors are important determinants of prenatal development that program adult phenotype. However, data on magnitude and specificity of maternal and paternal genome effects on fetal bone are lacking. We used an outbred bovine model to dissect and quantify effects of parental genomes, fetal sex, and nongenetic maternal effects on the fetal skeleton and analyzed phenotypic and molecular relationships between fetal muscle and bone. Analysis of 51 bone morphometric and weight parameters from 72 fetuses recovered at day 153 gestation (54% term) identified six principal components (PC1–6) that explained 80% of the variation in skeletal parameters. Parental genomes accounted for most of the variation in bone wet weight (PC1, 72.1%), limb ossification (PC2, 99.8%), flat bone size (PC4, 99.7%), and axial skeletal growth (PC5, 96.9%). Limb length showed lesser effects of parental genomes (PC3, 40.8%) and a significant nongenetic maternal effect (gestational weight gain, 29%). Fetal sex affected bone wet weight (PC1, p < 0.0001) and limb length (PC3, p < 0.05). Partitioning of variation explained by parental genomes revealed strong maternal genome effects on bone wet weight (74.1%, p < 0.0001) and axial skeletal growth (93.5%, p < 0.001), whereas paternal genome controlled limb ossification (95.1%, p < 0.0001). Histomorphometric data revealed strong maternal genome effects on growth plate height (98.6%, p < 0.0001) and trabecular thickness (85.5%, p < 0.0001) in distal femur. Parental genome effects on fetal bone were mirrored by maternal genome effects on fetal serum 25‐hydroxyvitamin D (96.9%, p < 0.001) and paternal genome effects on alkaline phosphatase (90.0%, p < 0.001) and their correlations with maternally controlled bone wet weight and paternally controlled limb ossification, respectively. Bone wet weight and flat bone size correlated positively with muscle weight (r = 0.84 and 0.77, p < 0.0001) and negatively with muscle H19 expression (r = –0.34 and –0.31, p < 0.01). Because imprinted maternally expressed H19 regulates growth factors by miRNA interference, this suggests muscle‐bone interaction via epigenetic factors. © 2014 American Society for Bone and Mineral Research.  相似文献   
75.
As the COVID-19 pandemic continues its journey around the world, it has triggered a global nursing response, with nurses everywhere working to save the lives of their extremely sick patients. In parallel with the frontline response, the International Council of Nurses, the World Health Authority and the International Confederation of Midwives have used their biennial Triad meetings to set out what needs to be done from a global perspective to protect nurses and the people they serve. At a time of crisis, it is imperative that the world’s nursing leaders, through ICN’s National Nursing Associations, step up to give support and guidance at this historically unsettling time.  相似文献   
76.

Background

Early environmental exposures may help shape the development of the autonomic nervous system (ANS) and hypothalamic–pituitary–adrenal (HPA) axis, influencing vulnerability for health problems across the lifespan. Little is known about the role of maternal sensitivity in influencing the development of the ANS in early life.

Aims

To examine associations among maternal sensitivity and infant behavioral distress and ANS and HPA axis reactivity to the Repeated Still-Face Paradigm (SFP-R), a dyadic stress task.

Study design

Observational repeated measures study.

Subjects

Thirty-five urban, sociodemographically diverse mothers and their 6-month-old infants.

Outcome measures

Changes in infant affective distress, heart rate, respiratory sinus arrhythmia (RSA), and T-wave amplitude (TWA) across episodes of the SFP-R were assessed. A measure of cortisol output (area under the curve) in the hour following cessation of the SFP-R was also obtained.

Results

Greater maternal insensitivity was associated with greater infant sympathetic activation (TWA) during periods of stress and tended to be associated with greater cortisol output following the SFP-R. There was also evidence for greater affective distress and less parasympathetic activation (RSA) during the SFP-R among infants of predominantly insensitive mothers.

Conclusions

Caregiving quality in early life may influence the responsiveness of the sympathetic and parasympathetic branches of the ANS as well as the HPA axis. Consideration of the ANS and HPA axis systems together provides a fuller representation of adaptive versus maladaptive stress responses. The findings highlight the importance of supporting high quality caregiving in the early years of life, which is likely to promote later health.  相似文献   
77.
78.
79.
Serum interleukin-10 in non-Hodgkin's lymphoma: a prognostic factor   总被引:13,自引:4,他引:13  
Serum interleukin-10 (IL-10) was measured retrospectively in 153 patients with a fully documented history of non-Hodgkin's lymphoma (NHL) using an enzyme-linked immunosorbent assay (ELISA) detecting both human IL-10 and the Epstein-Barr virus (EBV) molecule BCRF1/viral IL- 10. IL-10 was detectable in 47 (46%) of the 101 patients with active NHL, 3 of 52 (6%) patients in first partial or complete response, and none of the 60 healthy blood donors. Serum IL-10 was detectable with a similar frequency in all subtypes of NHL and in all clinical stages, as well as in EBV-seropositive and EBV-negative patients. In patients with intermediate or high-grade NHL, the presence of detectable serum IL-10 at diagnosis was correlated to a significantly shorter overall (P = .025) and progression-free (P = .030) survival. Patients with stage IV disease and detectable serum IL-10 had a particularly poor prognosis (4 years of survival: 0%). Multivariate analysis showed that IL-10 was an independent prognosis factor. These results indicate that IL-10 is detectable in a subgroup of patients with active NHL and correlates to a poor survival in patients with intermediate or high-grade NHL.  相似文献   
80.
Previous reports indicate that metronidazole is highly effective in the therapy of colonic amebiasis and in the treatment of hepatic amebic abscesses when combined with aspiration. A retrospective review of 15 cases of intestinal amebiasis and 12 patients with amebic liver abscesses treated with metronidazole alone is reported. Based on the literature and the clinical response of the patients reported herein, metronidazole is the initial drug of choice in the therapy of amebic colitis because of its ease of administration, efficacy, and low toxicity. In the treatment of hepatic amebic abscesses, metronidazole alone is adequate therapy for most cases, but occasionally there will be progression of the disease despite standard dosages of the drug.  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