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   3098篇
  免费   361篇
  国内免费   31篇
耳鼻咽喉   10篇
儿科学   45篇
妇产科学   59篇
基础医学   414篇
口腔科学   95篇
临床医学   357篇
内科学   703篇
皮肤病学   24篇
神经病学   365篇
特种医学   209篇
外科学   328篇
综合类   104篇
一般理论   4篇
预防医学   359篇
眼科学   21篇
药学   235篇
中国医学   3篇
肿瘤学   155篇
  2021年   57篇
  2020年   36篇
  2019年   47篇
  2018年   57篇
  2017年   32篇
  2016年   41篇
  2015年   53篇
  2014年   54篇
  2013年   94篇
  2012年   119篇
  2011年   155篇
  2010年   86篇
  2009年   74篇
  2008年   130篇
  2007年   144篇
  2006年   136篇
  2005年   144篇
  2004年   124篇
  2003年   110篇
  2002年   87篇
  2001年   94篇
  2000年   86篇
  1999年   79篇
  1998年   65篇
  1997年   49篇
  1996年   41篇
  1995年   29篇
  1994年   54篇
  1993年   45篇
  1992年   74篇
  1991年   57篇
  1990年   54篇
  1989年   72篇
  1988年   64篇
  1987年   45篇
  1986年   47篇
  1985年   56篇
  1984年   49篇
  1983年   29篇
  1982年   33篇
  1981年   32篇
  1979年   36篇
  1978年   34篇
  1976年   31篇
  1975年   29篇
  1973年   29篇
  1972年   30篇
  1969年   28篇
  1968年   34篇
  1966年   34篇
排序方式: 共有3490条查询结果,搜索用时 15 毫秒
81.
82.
83.
Introduction: Multimorbidity, the presence of multiple coexisting diseases or conditions, afflicts the majority of older adults, and is associated with increased mortality and healthcare utilization. In addition, multimorbidity negatively impacts quality of life and increases symptom burden. Yet, there is a dearth of evidence on how to best manage symptoms in patients with multimorbidity.

Methods: We conducted a thematic review of approaches to symptom management in multimorbidity.

Results: Research in this area has been hampered by inconsistent definitions of multimorbidity and challenges in outcome measurement. Investigations of symptom management strategies in specific disease states, like cancer, typically exclude medically complex patients. In the absence of evidence, the American Geriatrics Society's recommendations for the care of adults with multimorbidity provide a useful starting point for clinicians. We present a case to demonstrate how the AGS recommendations can be tailored to the situation of symptom management in patients with multimorbidity. We also present suggestions for future research directions.

Discussion: Multimorbidity is an incredibly common and overlooked problem in our healthcare system, and only stands to increase in relevance as patients live longer and have the opportunity to accrue a greater burden of chronic illness. A comprehensive approach to patients with multimorbidity includes focusing on patient preferences, carefully interpreting the available evidence (including both the benefits and potential harms), and thinking critically about the burden of any treatment. Taking time to elicit patient goals and preferences, and apprise patients of their prognosis if they want to know, are especially important in symptom management discussions with patients with multimorbidity.  相似文献   

84.
85.

Introduction

The median survival of patients with glioblastoma multiforme (astrocytoma grade 4) remains less than 18 months despite radical surgery, radiotherapy and systemic chemotherapy. Surgical implantation of chemotherapy eluting wafers into the resection cavity has been shown to improve length of survival but the current licensed therapy has several drawbacks. This paper investigates in vivo efficacy of a novel drug eluting paste in glioblastoma.

Methods

Poly(lactic-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) self-sintering paste was loaded with the chemotherapeutic agent etoposide and delivered surgically into partially resected tumours in a flank murine glioblastoma xenograft model.

Results

Surgical delivery of the paste was successful and practical, with no toxicity or surgical morbidity to the animals. The paste was retained in the tumour cavity, and preliminary results suggest a useful antitumour and antiangiogenic effect, particularly at higher doses. Bioluminescent imaging was not affected significantly by the presence of the paste in the tumour.

Conclusions

Chemotherapy loaded PLGA/PEG paste seems to be a promising technology capable of delivering active drugs into partially resected tumours. The preliminary results of this study suggest efficacy with no toxicity and will lead to larger scale efficacy studies in orthotopic glioblastoma models.  相似文献   
86.
Increased IgG and oligoclonal bands are found in cerebrospinal fluid of humans with chronic infectious CNS disease. Studies have shown that these oligoclonal bands are antibodies directed against the agent that causes disease. Laser-capture microdissection was used to isolate individual CD38+ plasma cells from the brain of a patient with subacute sclerosing panencephalitis, and single-cell RT-PCR was used to analyze individual IgG heavy and light chains expressed by each cell. Based on overrepresented IgG sequences, we constructed functional recombinant antibodies (recombinant IgGs) and determined their specificities. Five of eight recombinant IgGs recognized measles virus, the cause of subacute sclerosing panencephalitis. These results demonstrate that overrepresented IgG sequences in postmortem brains can be used to produce functional recombinant antibodies that recognize their target antigens. This strategy can be used to identify disease-relevant antigens in CNS inflammatory diseases of unknown etiology.  相似文献   
87.
Transaxial tomograhic imaging with thallium-201 was compared with standard, planar imaging in 38 patients with remote myocardial infarction and in 15 normal patients. Tomographic images were reconstructed from 64 views collected by a gamma camera that rotated about the anterior circumference of the patient's chest. A series of consecutive transverse-section images which encompassed the cardiac volume were reconstructed at a 6 mm plane spacing by filtered back-projection. No correction was made for attenuation losses. The set of transverse-section images was reformatted by 3-dimensional interpolation to obtain tomograms along the long and short axes of the myocardium. Tomographic and planar images were interpreted qualitatively.

Overall, tomography detected 33 of 38 (87%) prior infarctions whereas planar imaging detected 24 of 38 (63 %) (p = 0.01). Improvement of the tomographic imaging method occurred only in the combined subset of transmural inferior and subendocardial infarctions, and not in transmural anterior infarctions. Peak increases in creatinine phosphokinase were smaller in patients detected only by tomography compared with those detected by both the planar and the tomographic approach (3.1 × normal versus 10.4 × normal, p = 0.04). Five patients (13%) with prior infarction were not detected by either approach. For 6 of the 9 patients detected by tomography alone, realignment of the image data along the short and long axes of the heart was essential for making the diagnosis. Fourteen of 15 patients without infarction were normal on both planar and tomographic imaging. A single normal patient had a defect detected by both techniques, yielding a specificity of 93% for each.

We conclude that transaxial tomography significantly improves the detection of thallium-201 myocardial perfusion defects in patients with prior myocardial infarction.  相似文献   

88.
Low doses (50-200 pg or 3.1-12.4 fmol) of interleukin 1 (IL-1) infused into the brain of rats produced rapid suppression of various cellular immune responses in peripheral lymphocytes of rats. Fifteen minutes after infusion of purified IL-1 beta into the lateral ventricle, natural killer cell activity, response to phytohemagglutinin stimulation, and interleukin 2 production were markedly suppressed in lymphocytes isolated from blood and spleen. These effects were due to infusion of IL-1 into brain since they did not occur when IL-1 was infused into the cisterna magna (essentially posterior to brain) or was injected intraperitoneally. Effects of IL-1 in brain could be blocked by simultaneous infusion of alpha-melanocyte-stimulating hormone, which is known to block the biological actions of IL-1. To stimulate release of endogenous IL-1 in brain, lipopolysaccharide was infused; this produced similar effects as IL-1, and these effects also were blocked by alpha-melanocyte-stimulating hormone. At longer intervals after infusion of IL-1 and lipopolysaccharide (3, 6, and 24 hr), immune responses returned to baseline or remained suppressed; i.e., "rebound" immunopotentiation did not occur. Finally, IL-1 infusion suppressed cellular immune responses in adrenalectomized animals, thereby showing that the effects of central IL-1 on peripheral cellular immune responses were, at least in part, independent of the stimulatory effect of IL-1 on secretion of adrenal hormones. These results indicate a link from brain to peripheral immune responses by means of action of a cytokine acting in the brain.  相似文献   
89.
OBJECTIVES: Aboriginal children in tropical Australia have a high prevalence of both iron deficiency and acute infections, making it difficult to differentiate their relative contributions to anaemia. The aims of this study were to compare soluble transferrin receptor with ferritin in iron deficiency anaemia (IDA), and to examine how best to distinguish the effect of iron deficiency from infection on anaemia. METHODS: We conducted a prospective study of 228 admissions to Royal Darwin Hospital in children from 6 to 60 months of age. Transferrin receptor concentrations were measured by a particle-enhanced immunoturbidimetric assay and ferritin by a microparticle enzyme immunoassay. RESULTS: On multiple regression, the best explanatory variables for haemoglobin differences (r2=33.7%, P<0.001) were mean corpuscular volume (MCV), red cell distribution width (RDW) and C-reactive protein (CRP); whereas transferrin receptor and ferritin were not significant (P>0.4). Using > or =2 abnormal indices (MCV, RDW, blood film)+haemoglobin <110 g/l as the reference standard for IDA, transferrin receptor produced a higher area under the curve on receiver operating characteristic curve analysis than ferritin (0.79 vs. 0.64, P<0.001) or the transferrin receptor-ferritin index (0.77). On logistic regression, the effect of acute infection (CRP) on haemoglobin was significant (P<0.001) at cut-offs of 105 and 110 g/l, but not at 100 g/l when only iron deficiency indicators (MCV, RDW, blood film) were significant. CONCLUSIONS: Transferrin receptor does not significantly improve the diagnosis of anaemia (iron deficiency vs. infection) over full blood count and CRP, but in settings with a high burden of infectious diseases and iron deficiency, it is a more reliable adjunctive measure of iron status than ferritin.  相似文献   
90.
The HTLV-I tax gene protein (Tax) is not packaged within the mature viral particle from which the proteins for the commercially available enzyme-linked immunosorbent assay (ELISA) are derived. Screening of 162 individuals within a cohort of white intravenous (IV) drug abusers, previously identified as having an increased incidence of HTLV-I infection, demonstrated that seven of them had antibodies to the HTLV-I Tax protein but tested negative in HTLV-I ELISAs and Western blots prepared from purified virion proteins. Three out of 35 individuals in other behaviorally defined high-risk groups also displayed this limited pattern of reactivity to HTLV-I proteins. The presence of the anti-HTLV- I p40/Tax antibodies was determined by radioimmunoprecipitation assay (RIPA), which also revealed low levels of anti-env reactivity. The specificity of the anti-p40 reactivity was confirmed on specific Tax ELISAs and Western blots prepared from recombinantly produced Tax. In vitro gene amplification by the polymerase chain reaction (PCR) was used to establish the presence of sequences homologous to HTLV-I proviral DNA in four/four of these HTLV-I ELISA negative, Tax ELISA/Tax western blot/RIPA positive individuals. These data suggest that the true incidence of HTLV-I infection within high-risk cohorts is greater than previously reported.  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