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   2194篇
  免费   119篇
  国内免费   8篇
耳鼻咽喉   29篇
儿科学   70篇
妇产科学   33篇
基础医学   160篇
口腔科学   75篇
临床医学   217篇
内科学   450篇
皮肤病学   94篇
神经病学   139篇
特种医学   51篇
外科学   470篇
综合类   47篇
一般理论   4篇
预防医学   51篇
眼科学   140篇
药学   112篇
中国医学   8篇
肿瘤学   171篇
  2023年   19篇
  2022年   33篇
  2021年   93篇
  2020年   43篇
  2019年   89篇
  2018年   97篇
  2017年   71篇
  2016年   76篇
  2015年   93篇
  2014年   126篇
  2013年   150篇
  2012年   167篇
  2011年   197篇
  2010年   96篇
  2009年   85篇
  2008年   115篇
  2007年   110篇
  2006年   114篇
  2005年   94篇
  2004年   101篇
  2003年   79篇
  2002年   82篇
  2001年   10篇
  2000年   10篇
  1999年   9篇
  1998年   17篇
  1997年   11篇
  1996年   11篇
  1995年   12篇
  1994年   14篇
  1993年   6篇
  1992年   7篇
  1991年   10篇
  1990年   7篇
  1989年   11篇
  1988年   10篇
  1987年   7篇
  1986年   4篇
  1985年   3篇
  1983年   1篇
  1982年   2篇
  1981年   5篇
  1980年   1篇
  1979年   6篇
  1978年   3篇
  1977年   2篇
  1976年   3篇
  1974年   2篇
  1973年   2篇
  1971年   3篇
排序方式: 共有2321条查询结果,搜索用时 531 毫秒
91.

Objective

The aim of this work was to evaluate the hypothesis that the distribution of circulating immune cell subsets, or their activation state, is significantly different between peripartum cardiomyopathy (PPCM) and healthy postpartum (HP) women.

Background

PPCM is a major cause of maternal morbidity and mortality, and an immune-mediated etiology has been hypothesized. Cellular immunity, altered in pregnancy and the peripartum period, has been proposed to play a role in PPCM pathogenesis.

Methods

The Investigation of Pregnancy-Associated Cardiomyopathy (IPAC) study enrolled 100 women presenting with a left ventricular ejection fraction of <0.45 within 2 months of delivery. Peripheral T-cell subsets, natural killer (NK) cells, and cellular activation markers were assessed by flow cytometry in PPCM women early (<6 wk), 2 months, and 6 months postpartum and compared with those of HP women and women with non–pregnancy-associated recent-onset cardiomyopathy (ROCM).

Results

Entry NK cell levels (CD3–CD56+CD16+; reported as % of CD3– cells) were significantly (P?<?.0003) reduced in PPCM (6.6?±?4.9% of CD3– cells) compared to HP (11.9?±?5%). Of T-cell subtypes, CD3+CD4–CD8–CD38+ cells differed significantly (P?<?.004) between PPCM (24.5?±?12.5% of CD3+CD4–CD8– cells) and HP (12.5?±?6.4%). PPCM patients demonstrated a rapid recovery of NK and CD3+CD4–CD8–CD38+ cell levels. However, black women had a delayed recovery of NK cells. A similar reduction of NK cells was observed in women with ROCM.

Conclusions

Compared with HP control women, early postpartum PPCM women show significantly reduced NK cells, and higher CD3+CD4–CD8–CD38+ cells, which both normalize over time postpartum. The mechanistic role of NK cells and “double negative” (CD4–CD8–) T regulatory cells in PPCM requires further investigation.  相似文献   
92.
Familial hemophagocytic lymphohistiocytosis (FHL) is an inherited, fatal disorder of infancy. We report here a 17-day-old female infant who presented with high fever, hepatosplenomegaly, hypertriglyceridemia, hypofibrinogenemia, thrombocytopenia, and liver failure. Leukocytosis was detected with circulating "atypical" lymphoid cells. Flow cytometric studies revealed expanded subpopulations of CD8+ T cells with unusual immunophenotypic features, including a subset that lacked CD5 expression. A liver biopsy showed hemophagocytic lymphohistiocytosis with exuberant infiltrates of CD8+ T cells that lacked perforin. Mutational studies revealed a 666C-->A (H222Q) missense mutation in the perforin gene. T-cell receptor studies on flow-sorted T-cell subpopulations revealed no evidence of monoclonality. Analysis of T-cell receptor excision circle levels indicated long proliferative history in the aberrant CD8+ T-cell subsets. This case provides an instructive example of uncontrolled reactive proliferation of CD8+ T cells in FHL, resulting in atypical morphology and unusual immunophenotypic features that might suggest malignancy in other clinical settings.  相似文献   
93.
94.
95.
Monoclonal gammopathy of undetermined significance (MGUS) affects 3·2% of adults aged >50 years. MGUS carries a life-long risk of progression to multiple myeloma and causes complications including infection and renal impairment; common causes of hospital admission. This study aimed to assess MGUS prevalence in emergency medical hospital admissions. Patients were recruited from unselected emergency medical admissions in a hospital in the United Kingdom. Serum protein electrophoresis was performed, with immunofixation of abnormal results. Reason for admission and routine test results were recorded. After education about MGUS and myeloma, patients chose whether they wished to be informed of new diagnoses. A total of 660 patients were tested and 35 had a paraprotein suggestive of MGUS. The overall rate of MGUS was 5·3%. MGUS prevalence in those aged >50 years was 6·94%, higher than the previously published rate of 3·2% (P < 0·0005). There were higher rates in those with chronic kidney disease (13·75% vs. 4·14%, P = 0·002), heart failure (14% vs. 4·59%, P = 0·012), anaemia (8·96% vs. 3·41%, P = 0·003) or leucocytosis (9·33% vs. 3·04%, P = 0·002). In all, 96% of patients wished to be informed of their screening results. The prevalence of MGUS in emergency hospital admissions is higher than expected based on previous population-based rates. This may suggest a selected population for screening.  相似文献   
96.
Recurrence after curative resection of gastrointestinal (GI) cancers is common. Early detection of resectable recurrences may result in a curative resection. In un-resectable recurrences, early detection may improve the quality of life by palliation or with the use of newer chemotherapeutic drugs. The guidelines regarding follow-up of patients after curative resection of GI cancers are from the West which is very different from the Indian population in terms of a disease pattern and social milieu. The guidelines which are commonly used are also not strictly followed. We have proposed in this article the protocols which we follow at our centre after curative resection of GI cancer and how these are different from the guidelines proposed by the West.  相似文献   
97.
98.
99.
100.
BackgroundApproximately 20% of the US population live in states where MAiD is a legal, though highly contentious, practice. Little generalizable data exists on the experiences of MAiD providers who comprise a small, and intentionally hidden, population.ObjectiveTo examine the nature, extent, and consequences of physicians’ participation in MAiD.DesignAn anonymous, multi-wave, mailed survey (RR= 55%).ParticipantsAn enriched sample (n=583) of Colorado physicians caring for potential MAiD patients.Main MeasuresPhysician willingness, preparedness, and participation in a continuum of MAiD activities. Other outcomes include the effects of providing MAiD and the barriers physicians face related to MAiD.Key ResultsOverall, 81.1% of respondents were willing to discuss MAiD with a patient, 88.3% to refer for MAiD, 46.3% to be a consultant, and 28.1% to be an attending. Fewer felt prepared to discuss MAiD (54.4%), provide a MAiD referral (62.8%), be a consultant (30.7%), or be an attending (18.0%). More than half of respondents (52.3%) had discussed MAiD with a patient, 27.3% provided a MAiD referral, 12.8% had been a MAiD consultant, and 8.5% had been a MAiD attending. Among MAiD consultants and attendings, 75% reported that their most recent MAiD case was emotionally fulfilling and professionally rewarding, though 75% also reported that it was time consuming and 46.9% reported that it was ethically challenging. Common barriers to physician participation in MAiD include lack of knowledge about MAiD (46.8%), the emotional (45.6%) and time (41.7%) investments, and ethical concerns (41.7%).ConclusionsMany physicians in our sample are both willing and prepared to discuss MAiD with patients and to provide MAiD referrals. Fewer are prepared and willing to serve as an attending or consultant and fewer have provided these services. MAID consultants and attendings largely report the experience to be emotionally fulfilling and professionally rewarding, but all respondents reported multiple barriers to participation.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11606-021-07300-8.KEY WORDS: physician assisted death, physician assisted suicide, medical aid in the dying  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