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   521篇
  免费   15篇
  国内免费   9篇
耳鼻咽喉   1篇
儿科学   42篇
妇产科学   9篇
基础医学   52篇
口腔科学   9篇
临床医学   44篇
内科学   149篇
皮肤病学   10篇
神经病学   3篇
特种医学   131篇
外科学   18篇
综合类   10篇
预防医学   12篇
眼科学   9篇
药学   21篇
  1篇
中国医学   6篇
肿瘤学   18篇
  2022年   3篇
  2021年   4篇
  2018年   5篇
  2017年   4篇
  2016年   3篇
  2015年   5篇
  2014年   10篇
  2013年   12篇
  2012年   8篇
  2011年   5篇
  2010年   23篇
  2009年   21篇
  2008年   12篇
  2007年   14篇
  2006年   10篇
  2005年   3篇
  2004年   3篇
  2003年   9篇
  2002年   3篇
  2001年   12篇
  2000年   6篇
  1999年   6篇
  1998年   27篇
  1997年   27篇
  1996年   40篇
  1995年   36篇
  1994年   34篇
  1993年   18篇
  1992年   3篇
  1991年   10篇
  1990年   4篇
  1989年   18篇
  1988年   23篇
  1987年   17篇
  1986年   14篇
  1985年   16篇
  1984年   11篇
  1983年   7篇
  1982年   6篇
  1981年   9篇
  1980年   11篇
  1979年   3篇
  1978年   3篇
  1977年   8篇
  1976年   7篇
  1975年   4篇
  1973年   2篇
  1970年   1篇
  1965年   1篇
  1959年   1篇
排序方式: 共有545条查询结果,搜索用时 62 毫秒
51.

INTRODUCTION

Since the invasion of Iraq in 2003, the conflict has evolved from asymmetric warfare to a counter-insurgency operation. This study investigates the pattern of wounding and types of injuries seen in casualties of hostile action presenting to a British military field hospital during the present conflict.

PATIENTS AND METHODS

Data were prospectively collected on 100 consecutive patients either injured or killed from hostile action from January 2006 who presented to the sole coalition field hospital in southern Iraq.

RESULTS

Eighty-two casualties presented with penetrating missile injuries from hostile action. Three subsequently died of wounds (3.7%). Forty-six (56.1%) casualties had their initial surgery performed by British military surgeons. Twenty casualties (24.4%) sustained gunshot wounds, 62 (75.6%) suffered injuries from fragmentation weapons. These 82 casualties were injured in 55 incidents (mean, 1.49 casualties; range 1–6 casualties) and sustained a total 236 wounds (mean, 2.88 wounds) affecting a mean 2.4 body regions per patient. Improvised explosive devices were responsible for a mean 2.31 casualties (range, 1–4 casualties) per incident.

CONCLUSIONS

The current insurgency in Iraq illustrates the likely evolution of modern, low-intensity, urban conflict. Improvised explosive devices employed against both military and civilian targets have become a major cause of injury. With the current global threat from terrorist bombings, both military and civilian surgeons should be aware of the spectrum and emergent management of the injuries caused by these weapons.  相似文献   
52.
The Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) Phase 1 Schizophrenia trial compared the effectiveness of one typical and four atypical antipsychotic medications. Although trials such as CATIE present important opportunities for pharmacogenetics research, the very richness of the clinical data presents challenges for statistical interpretation, and in particular the risk that data mining will lead to false-positive discoveries. For this reason, it is both misleading and unhelpful to perpetuate the current practice of reporting association results for these trials one gene at a time, ignoring the fact that multiple gene-by-phenotype tests are being carried out on the same data set. On the other hand, suggestive associations in such trials may lead to new hypotheses that can be tested through both replication efforts and biological experimentation. The appropriate handling of these forms of data therefore requires dissemination of association statistics without undue emphasis on select findings. Here we attempt to illustrate this approach by presenting association statistics for 2769 polymorphisms in 118 candidate genes evaluated for 21 pharmacogenetic phenotypes. On current evidence it is impossible to know which of these associations may be real, although in total they form a valuable resource that is immediately available to the scientific community.  相似文献   
53.

Background and purpose:

Angiotensin II receptor antagonists (ARBs), originally developed for antihypertensive properties, have pleiotropic effects including direct vascular actions. We tested the hypothesis that the ARB irbesartan would be effective against micro- and macrovascular complications of the prediabetic metabolic syndrome using the obese, insulin-resistant JCR : LA-cp rat that exhibits micro- and macrovascular disease with ischaemic myocardial lesions and renal disease.

Experimental approach:

Obese male rats were treated with irbesartan (30 mg·kg−1·day−1, incorporated into chow) from 12 to 25 weeks of age.

Key results:

Irbesartan treatment caused no change in food intake or body weight. Fasting glycaemic control of the JCR : LA-cp rats was marginally improved, at the expense of increased plasma insulin levels (∼50%). Fasting plasma triglycerides were marginally reduced (∼25%), while cholesterol concentrations were unchanged. Elevated concentrations of adiponectin, monocyte chemotactic protein-1 and plasminogen activator inhibitor-1 were reduced along with severity of glomerular sclerosis. Macrovascular dysfunction (aortic hypercontractile response to noradrenergic stimulus and reduced endothelium-dependent relaxation) was improved and frequency of ischaemic myocardial lesions reduced (62%).

Conclusions and implications:

Irbesartan reduces markers of inflammation and prothombotic status, improves macrovascular function and reduces glomerular sclerosis and myocardial lesions in a model of the metabolic syndrome. Unlike pharmaceutical agents targeted on metabolic dysfunction, irbesartan reduced end-stage disease without major reduction of plasma lipids or insulin. The protective effects appear to be secondary to unknown intracellular mechanisms, probably involving signal transduction pathways. Understanding these would offer novel pharmaceutical approaches to protection against cardiovascular disease.  相似文献   
54.
Twenty-six patients over the age of 50 years with proven iron deficiency anaemia were identified, investigated and followed up in general practice over a five-year period. The anaemia was symptomatic in 50% of patients but only 20% had symptoms related to the gut. Faecal occult blood testing was positive in five patients only and negative tests occurred in three patients with significant disease, including one caecal carcinoma. All patients agreed to oesophagogastroduodenoscopy (OGD) and fibreoptic sigmoidoscopy carried out on the same occasion. In eight patients, significant abnormalities were found on OGD and in two patients on sigmoidoscopy. Four patients declined barium enema examinations, two of whom had significant OGD abnormalities. Barium enema examination of the other 22 patients showed polyposis of the colon and a caecal carcinoma and initially missed one carcinoma of the caecum which was found subsequently. The likelihood of finding significant disease in iron-deficient patients over 50 years of age is high and should be assumed to be due to blood loss into the gut. Investigation by OGD, sigmoidoscopy and barium enema in the first instance seems warranted and is a condition that can be safely managed by the GP. (Br J Clin Pract 1997; 51(2) : 78-80)  相似文献   
55.
The amino acid sequence of guinea pig MSEL-neurophysin has been determined using tryptic peptides derived from the performic acid-oxidized protein and staphylococcal proteinase peptides obtained from the reduced-carboxamidomethylated neur-ophysin. Guinea pig MSEL-neurophysin consists of a 93-residue polypeptide chain that shows 12 substitutions and 2 deletions when compared to bovine MSEL-neurophysin. It displays the highest number of variations among known mammalian MSEL-neurophysins. These variations are mainly found in the C-terminal region (residues 88–93). Moreover guinea pig MSEL-neurophysin, like rat homologous protein, exhibits substitutions in positions 2, 5, 29 and 81 and lacks an arginine in the penultimate position. Comparison between eight mammalian MSEL-neurophysins reveals a highly conserved region (residues 1 to 88) and a hypervariable region (residues 89 to 93/95). On the other hand the eight species examined are endowed with arginine vasopressin except pig, which has a lysine vasopressin. In the vasopressin-MSEL-neurophysin precursor, the hormonal moiety and the MSEL region of neurophysin (residues 1–9) are encoded by a common exon in ox, rat and man; it can be concluded that this exon is evolutionarily conservative in contrast to the one encoding the C-terminal region of MSEL-neurophysin.  相似文献   
56.
Erythropoietin kinetics in rats: generation and clearance   总被引:1,自引:0,他引:1  
Steinberg  SE; Garcia  JF; Matzke  GR; Mladenovic  J 《Blood》1986,67(3):646-649
Detailed studies to analyze the early events of erythropoietin (Ep) secretion and clearance were performed in a rat model using a double antibody radioimmunoassay. Ep clearance was determined following intravenous injection of 1 mL of Ep-rich plasma, 1,080 mU/mL, obtained from phlebotomized rats. Analysis revealed a disappearance curve that conformed to a two-compartment model with an alpha half-life t1/2 of 3.6 minutes and a beta t1/2 of 86 minutes. The volume of distribution was similar to the calculated plasma volume. In anephric animals, there was no change in the plasma clearance rate or the volume of distribution. Rapid Ep secretion was elicited by a single 15 mL/kg phlebotomy (hematocrit decrement 45% to 30%), so that levels reached 20 to 30 times baseline (524 +/- 76 v 24 +/- 7 mU/mL) at five hours, whereas they plateaued for at least 33 hours. The increase in the rate of secretion was geometric, from 9.9 mU/h baseline secretion to 429 mU/h. These data identify a very sensitive and rapidly responsive system for Ep modulation in the rat.  相似文献   
57.
58.
Linkage analysis was performed on a large pedigree with an autosomal dominant platelet disorder and a striking propensity in affected family members to develop hematologic malignancy, predominantly acute myelogenous leukemia. We report the linkage of the autosomal dominant platelet disorder to markers on chromosome 21q22. Four genetic markers completely cosegregate with the trait and yield maximum logarithm of difference scores ranging from 4.9 to 10.5 (theta = .001). Two flanking markers, D21S1265 and D21S167, define a critical region for the disease locus of 15.2 centimorgan. Further analysis of this locus may identify a gene product that affects platelet production and function and contributes to the molecular evolution of hematologic malignancy.  相似文献   
59.
Clonal rearrangements of the Ig heavy chain (IGH) locus occur in nearly all cases of B-cell precursor acute leukemia (BCP-ALL). Some of these rearrangements may be detected by polymerase chain reaction (PCR) using VH gene framework III (FRIII) and JH consensus primers. However, about 20% of BCP-ALLs fail to amplify with this technique. To determine the causes of these PCR failures and to investigate any possible association with specific subgroups of disease, we analyzed 72 acute leukemias of defined immunophenotype and cytogenetics, comparing FRIII with VH-family leader-specific PCR methods and Southern blotting. Of 37 BCP-ALL cases, 6 (16.2%) failed totally to amplify with FRIII and JH primers. None of these cases amplified with VH leader primers. Additionally, all cases retained germline VH6 genes and 5 of 11 rearranged alleles amplified with a consensus DH primer, indicating that these rearrangements represented biallelic DH-JH recombinations. Among the 6 FRIII and VH leader PCR-negative BCP-ALL cases, there was no common immunophenotype or consistent cytogenetic abnormality, although all showed structural chromosomal abnormalities and 3 of 5 successfully karyotyped had abnormalities of chromosome 12p. 13 cases with t(9;22)(q34;q11) Philadelphia chromosome-positive [Ph+]) and IGH rearrangements (9 BCP-ALL and 4 biphenotypic cases) were also analyzed. Of 23 rearranged IGH alleles, 19 (82%) were positive by FRIII PCR, and all 4 remaining alleles were amplified by VH leader primers. Use of the leader primers in these Ph+ cases also detected 3 additional clonal rearrangements that were not anticipated from Southern blotting; such unexpected bands were not observed in 21 other Ph- cases. The additional bands represented "new" and unrelated VH rearrangements rather than VH-VH replacement events. We conclude that biallelic DHJH rearrangements occur in a subgroup of BCP-ALL; in these cases, the activation of the full VHDHJH recombination mechanism had not occurred. Therefore, these cases of BCP-ALL were arrested at an early stage of B- cell differentiation. In contrast, all Ph+ BCP-ALLs and biphenotypic acute leukemias, which may represent the transformation of multipotent hemopoietic stem cells, had undergone VHDHJH recombination. Of 9 Ph+ BCP-ALL cases, 3 also showed ongoing VHDHJH rearrangement, reflecting the persistent expression of the VHDHJH recombinase. Finally, sequence analysis of 33 rearranged VHDHJH genes showed that only 3 including 2 Ph+ BCP-ALL maintained an intact open-reading frame. Loss of the open- reading frame occurred not only because of out-of-frame VHDH and DHJH joining, but also because of VH gene mutation and deletion. These data show that most BCP-ALLs may represent the neoplastic transformation of BCPs destined to die in the bone marrow.  相似文献   
60.

Background

Direct stenting without balloon dilatation may reduce procedural costs and duration, and hypothetically, the restenosis rate. This study was designed to compare the in-hospital and long-term outcomes of direct stenting (DS) versus stenting after pre-dilatation (PS) in our routine clinical practice.

Methods

The 1 603 patients treated with stenting for single coronary lesions were enrolled into a prospective registry. Patients with acute myocardial infarction (MI) within the preceding 48 hours, and those with highly calcified lesions, total occlusions, or a lesion in a saphenous graft were excluded. The baseline, angiographic and procedural data, inhospital outcomes and follow-up data were recorded in our database and analysed with appropriate statistical methods.

Results

Eight hundred and fifty-seven patients (53.5%) were treated with DS and 746 (46.5%) underwent PS. In the DS group, lesions were shorter in length, larger in diameter and had lower pre-procedural diameter stenosis. Type C and diffuse lesions and drug-eluting stents were found less often (p < 0.001). With univariate analysis, dissection and non-Q-wave MI occurred less frequently in this group (0.2 and 0.6% vs 3.9 and 2.1%, p < 0.001 and p = 0.01, respectively). However, the cumulative major adverse cardiac events (MACE) did not differ significantly (4.9 vs 4.6%, p = 0.79). With multivariate analysis, direct stenting reduced the risk of dissection (OR = 0.07, 95% CI: 0.01–0.33, but neither the cumulative endpoint of MACE (OR = 1.1, 95% CI = 0.58–2.11, p = 0.7) nor its constructing components were different between the groups.

Conclusions

Direct stenting in the real world has at least similar long-term outcomes in patients treated with stenting after pre-dilatation, and is associated with lower dissection rates.  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