首页 | 官方网站   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   26562篇
  免费   1792篇
  国内免费   83篇
医药卫生   28437篇
  2021年   342篇
  2020年   227篇
  2019年   368篇
  2018年   427篇
  2017年   290篇
  2016年   362篇
  2015年   418篇
  2014年   627篇
  2013年   950篇
  2012年   1427篇
  2011年   1582篇
  2010年   952篇
  2009年   963篇
  2008年   1504篇
  2007年   1678篇
  2006年   1673篇
  2005年   1762篇
  2004年   1619篇
  2003年   1547篇
  2002年   1533篇
  2001年   425篇
  2000年   351篇
  1999年   404篇
  1998年   379篇
  1997年   340篇
  1996年   294篇
  1995年   277篇
  1994年   255篇
  1993年   236篇
  1992年   319篇
  1991年   305篇
  1990年   280篇
  1989年   258篇
  1988年   223篇
  1987年   221篇
  1986年   239篇
  1985年   224篇
  1984年   211篇
  1983年   202篇
  1982年   224篇
  1981年   236篇
  1980年   190篇
  1979年   146篇
  1978年   136篇
  1977年   143篇
  1976年   122篇
  1975年   119篇
  1974年   102篇
  1973年   107篇
  1972年   100篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.

Introduction

Bilateral adrenal hemorrhage remains a rare disease. It has several etiologies, and clinical presentation is not specific.

Case report

We report a 45-year old man without known prothrombotic factor who presented with acute left sided abdominal pain left revealing a bilateral adrenal hemorrhage. The diagnostic work-up identified a significant hyperhomocysteinemia associated with a previously undiagnosed homozygous mutation of the 5,10 methylene–tetrahydrofolate reductase gene. The outcome was associated with the occurrence of an adrenal insufficiency.  相似文献   
992.
993.
994.
Iron deficiency anemia (IDA) is the most common form of anemia worldwide. Although oral iron is used as first‐line treatment, many patients are unresponsive to or cannot take oral iron. This Phase III, open‐label, non‐inferiority study compared the efficacy and safety of ferumoxytol, a rapid, injectable intravenous (IV) iron product with low immunological reactivity and minimal detectable free iron, with IV iron sucrose in adults with IDA of any cause. Patients (N = 605) were randomized 2:1 to receive ferumoxytol (n = 406, two doses of 510 mg 5 ± 3 days apart) or iron sucrose (n = 199, five doses of 200 mg on five nonconsecutive days over 14 days) and followed for 5 weeks. Ferumoxytol demonstrated noninferiority to iron sucrose at the primary endpoint, the proportion of patients achieving a hemoglobin increase of ≥2 g dL?1 at any time from Baseline to Week 5 (ferumoxytol, 84.0% [n = 406] vs. iron sucrose, 81.4% [n = 199]), with a noninferiority margin of 15%. Ferumoxytol was superior to iron sucrose (2.7 g dL?1 vs. 2.4 g dL?1) in the mean change in hemoglobin from Baseline to Week 5 (the alternative preplanned primary endpoint) with P = 0.0124. Transferrin saturation, quality‐of‐life measures, and safety outcomes were similar between the two treatment groups. Overall, ferumoxytol demonstrated comparable safety and efficacy to iron sucrose, suggesting that ferumoxytol may be a useful treatment option for patients with IDA in whom oral iron was unsatisfactory or could not be used. Am. J. Hematol. 89:646–650, 2014. © 2014 Wiley Periodicals, Inc.  相似文献   
995.
Activated protein C resistance assays can detect factor V Leiden with high accuracy, depending on the method used. Factor Xa inhibitors such as rivaroxaban and direct thrombin inhibitors including dabigatran, argatroban, and bivalirudin can cause falsely normal results. Lupus anticoagulants can cause incorrect results in most current assays. Assays that include dilution into factor V‐deficient plasma are needed to avoid interference from factor deficiencies or elevations, which can arise from a wide variety of conditions such as warfarin, liver dysfunction, or pregnancy. The pros and cons of the currently available assays are discussed. Am. J. Hematol. 89:1147–1150, 2014. © 2014 Wiley Periodicals, Inc.  相似文献   
996.
BCR-ABL inhibitors for treating chronic myeloid leukemia in chronic phase have transformed a previously incurable malignancy into a manageable condition. However, suboptimal medication adherence has been observed with these agents affecting clinical outcomes and healthcare costs. In order to raise awareness of the problem of adherence, and before developing pragmatic strategies to enhance medication adherence, a deep understanding of the best approaches for measuring adherence in chronic myeloid leukemia patients and identifying non-adherence is required. A systematic literature review on the prevalence, measurement methods, consequences and risk factors for non-adherence to BCR-ABL inhibitors and adherence-enhancing interventions was performed and critically appraised. Of the 19 included articles, 9 were retrospective. Average adherence varied from 19% to almost 100% of the proportion of prescribed drug taken, but it was measured through various different methods and within different study groups. Suboptimal adherence was associated with a negative impact on both clinical and economic outcomes. There is a lack of supportive evidence demonstrating a difference in adherence across BCR-ABL inhibitors and even contradictory results between the 2nd generation inhibitors. Drug-related adverse events and forgetfulness were common reasons for intentional and unintentional non-adherence, respectively, but further research is required to identify additional reasons behind non-adherence or patients at risk of non-adherence. Non-adherence in chronic myeloid leukemia patients treated with BCR-ABL inhibitors is common and associated with critical outcomes. However, this review highlights important existing gaps, reveals inconsistent definitions, and a lack of standardized methods for measuring adherence in chronic myeloid leukemia. All require further investigation.  相似文献   
997.
We have reported encouraging results of unrelated cord blood transplantation for patients with lymphoid malignancies. Whether those outcomes are comparable to matched unrelated donor transplants remains to be defined. We studied 645 adult patients with mature lymphoid malignancies who received an allogeneic unrelated donor transplant using umbilical cord blood (n=104) or mobilized peripheral blood stem cells (n=541) after a reduced-intensity conditioning regimen. Unrelated cord blood recipients had more refractory disease. Median follow-up time was 30 months. Neutrophil engraftment (81% vs. 97%, respectively; P<0.0001) and chronic graft-versus-host disease (26% vs. 52%; P=0.0005) were less frequent after unrelated cord blood than after matched unrelated donor, whereas no differences were observed in grade II–IV acute graft-versus-host disease (29% vs. 32%), non-relapse mortality (29% vs. 28%), and relapse or progression (28% vs. 35%) at 36 months. There were also no significant differences in 2-year progression-free survival (43% vs. 58%, respectively) and overall survival (36% vs. 51%) at 36 months. In a multivariate analysis, no differences were observed in the outcomes between the two stem cell sources except for a higher risk of neutrophil engraftment (hazard ratio=2.12; P<0.0001) and chronic graft-versus-host disease (hazard ratio 2.10; P=0.0002) after matched unrelated donor transplant. In conclusion, there was no difference in final outcomes after transplantation between umbilical cord blood and matched unrelated donor transplant. Umbilical cord blood is a valuable alternative for patients with lymphoid malignancies lacking an HLA-matched donor, being associated with lower risk of chronic graft-versus-host disease.  相似文献   
998.

Background

Invasive assessment of coronary physiology (IACP) offers important prognostic insights in ST-segment elevation myocardial infarction (STEMI) but the dynamics of coronary recovery are poorly understood.

Objectives

This study sought to examine the evolution of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), ratio of distal coronary pressure (Pd) to mean aortic pressure (Pa), and fractional flow reserve (FFR) in patients undergoing primary percutaneous coronary intervention (PPCI).

Methods

82 patients with STEMI underwent IACP at PPCI. Repeat IACP was performed in 61 patients (74%) at day 1 and in 46 patients (56%) at 6 months. Contrast-enhanced cardiac magnetic resonance imaging (CMR) was performed in 45 patients (55%) at day 1 and in 41 patients (50%) at 6 months. Changes in IACP were compared between patients with and without microvascular obstruction (MVO) on CMR.

Results

MVO was present in 21 of 45 patients (47%). Patients with MVO had lower CFR at PPCI and day 1 (p < 0.05) and a trend toward higher IMR values (p = 0.07). At 6 months, CFR and IMR were not significantly different between the groups. Baseline flow and Pd/Pa remained stable over time but FFR reduced significantly between PPCI and 6 months (p = 0.008); this reduction was mainly observed in patients with MVO (p = 0.006) but not in those without MVO (p = 0.21).

Conclusions

In PPCI-treated patients with STEMI, coronary microcirculation begins to recover within 24 h and recovery progresses further by 6 months. FFR significantly reduces from baseline to 6 months. The presence of MVO indicates a highly dysfunctional microcirculation.  相似文献   
999.
STING (stimulator of IFN genes) activates the IFN-dependent innate immune response to infection on sensing the presence of DNA in cytosol. The quantity of STING accumulating in cultured cells varies; it is relatively high in some cell lines [e.g., HEp-2, human embryonic lung fibroblasts (HEL), and HeLa] and low in others (e.g., Vero cells). In a preceding publication we reported that STING was stable in four cell lines infected with herpes simplex virus 1 and that it was actively stabilized in at least two cell lines derived from human cancers. In this report we show that STING is exported from HEp-2 cells to Vero cells along with virions, viral mRNAs, microRNAs, and the exosome marker protein CD9. The virions and exosomes copurified. The quantity of STING and CD9 exported from one cell line to another was inoculum-size–dependent and reflected the levels of STING and CD9 accumulating in the cells in which the virus inoculum was made. The export of STING, an innate immune sensor, and of viral mRNAs whose major role may be in silencing viral genes in latently infected neurons, suggests that the virus has evolved mechanisms that curtail rather than foster the spread of infection under certain conditions.The stimulator of IFN genes (STING) is a sensor of cytoplasmic DNA and activates immune responses to intracellular pathogens (13). Knockout of STING exacerbates the pathogenicity of herpes simplex virus (HSV-1) and of other pathogens in mice (2, 3). Two observations reported earlier add to the role of STING in HSV-1 infected cells. Specifically, (i) STING was readily detectable and stable in four different cell lines infected with wild-type virus (4). The stability of STING in cells infected with an HSV-1 mutant lacking the gene encoding ICP0 (infected cell protein no. 0), a key viral regulatory protein, varied. STING was stable in ΔICP0 mutant virus infected cells derived from normal tissues but was rapidly degraded in infected cells derived from human cancers (4). Implicit in this observation is that ICP0 is required to stabilize STING, although STING could also be stabilized in the absence of ICP0 by a cellular function. (ii) Depletion of STING increased wild-type virus yield 10-fold in cells derived from normal tissues but decreased the yield by the same amount in cells derived from human cancer (4). Thus, at least in cells derived from normal tissues, HSV-1 expresses ICP0 that enables the stabilization of STING even though STING is inimical to virus growth. The results of these studies suggest that HSV-1 recruits STING for a specific function, even though the persistence of STING is not beneficial to virus growth, at least in cells derived from normal tissues (4).Here we report that STING, along with viral RNAs contained in structures that coprecipitate with exosome marker proteins, is exported from the cells in which virus is produced to uninfected cells. The quantities introduced into uninfected cells are dose-dependent and reflect the amounts produced in donor cells.Cells continuously secrete a large number of microvesicles, macromolecular complexes, and small molecules into the extracellular space (5, 6). Of the secreted microvesicles, exosomes are 30–120 nm in diameter, containing nucleic acid and proteins, and are perceived to be carriers of this cargo between diverse locations. They are distinguished in their genesis by being budded into endosomes to form multivesicular bodies (MVBs) in the cytoplasm. The exosomes are released to extracellular fluids by fusion of these multivesicular bodies with the cell surface, resulting in secretion (710).Several pathogens use the exosomes to manipulate their microenvironment (11, 12). Viruses, especially small retroviruses such as HIV, use the exosome pathway for egress and immune evasion (1315). The hepatitis C virus uses exosomes for invasion and spread (1618). EBV-infected cells release exosomes containing the latent membrane protein 1 to induce T-cell anergy (1923). In the case of human cytomegalovirus the exosomes carrying viral antigens exacerbate the transplant rejection process (24). It is likely that viruses that establish long-term, latent, or chronic infections modulate exosomes to enhance their persistence (11).Here we report that the exosomes secreted by HSV-1–infected cells deliver to uninfected cells the innate immune sensor STING along with viral RNAs. We speculate that in the long run the strategy serves the virus to fulfill its mission: to spread effectively from person to person.  相似文献   
1000.

Background

Despite extensive translational research, no validated biomarkers predictive of bevacizumab treatment outcome have been identified.

Methods

We performed a meta-analysis of individual patient data from six randomized phase III trials in colorectal, pancreatic, lung, renal, breast, and gastric cancer to explore the potential relationships between 195 common genetic variants in the vascular endothelial growth factor (VEGF) pathway and bevacizumab treatment outcome.

Results

The analysis included 1,402 patients (716 bevacizumab-treated and 686 placebo-treated). Twenty variants were associated (P < 0.05) with progression-free survival (PFS) in bevacizumab-treated patients. Of these, 4 variants in EPAS1 survived correction for multiple testing (q < 0.05). Genotype-by-treatment interaction tests revealed that, across these 20 variants, 3 variants in VEGF-C (rs12510099), EPAS1 (rs4953344), and IL8RA (rs2234671) were potentially predictive (P < 0.05), but not resistant to multiple testing (q > 0.05). A weak genotype-by-treatment interaction effect was also observed for rs699946 in VEGF-A, whereas Bayesian genewise analysis revealed that genetic variability in VHL was associated with PFS in the bevacizumab arm (q < 0.05). Variants in VEGF-A, EPAS1, and VHL were located in expression quantitative loci derived from lymphoblastoid cell lines, indicating that they affect the expression levels of their respective gene.

Conclusions

This large genetic analysis suggests that variants in VEGF-A, EPAS1, IL8RA, VHL, and VEGF-C have potential value in predicting bevacizumab treatment outcome across tumor types. Although these associations did not survive correction for multiple testing in a genotype-by-interaction analysis, they are among the strongest predictive effects reported to date for genetic variants and bevacizumab efficacy.  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-23

京公网安备 11010802026262号