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   1101篇
  免费   92篇
  国内免费   5篇
耳鼻咽喉   4篇
儿科学   29篇
妇产科学   22篇
基础医学   156篇
口腔科学   11篇
临床医学   114篇
内科学   228篇
皮肤病学   38篇
神经病学   100篇
特种医学   19篇
外科学   104篇
综合类   7篇
一般理论   4篇
预防医学   138篇
眼科学   39篇
药学   94篇
中国医学   7篇
肿瘤学   84篇
  2024年   3篇
  2023年   35篇
  2022年   46篇
  2021年   104篇
  2020年   41篇
  2019年   57篇
  2018年   72篇
  2017年   41篇
  2016年   40篇
  2015年   49篇
  2014年   47篇
  2013年   57篇
  2012年   105篇
  2011年   102篇
  2010年   55篇
  2009年   50篇
  2008年   68篇
  2007年   64篇
  2006年   32篇
  2005年   40篇
  2004年   25篇
  2003年   22篇
  2002年   15篇
  2000年   3篇
  1999年   3篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1995年   2篇
  1994年   5篇
  1993年   3篇
  1991年   1篇
  1989年   2篇
  1988年   1篇
  1985年   1篇
  1980年   1篇
排序方式: 共有1198条查询结果,搜索用时 15 毫秒
41.
42.
Papanicolaou tests are often repeated just before the procedure for women who have been referred for colposcopy. The validity and clinical usefulness of this practice, however, is unclear. We retrospectively assessed the value of repeated cytology in a cohort of 1,087 consecutive patients who underwent repeated Papanicolaou testing at first colposcopy. The repeated cytology was considered clinically useful if the results could conceivably have influenced the physician's decision about more invasive diagnostic/therapeutic evaluation based on contemporary practice guidelines. Repeated cytology provided potentially clinically useful information in only a small proportion (3.6%) of the cases analyzed overall, including 41% (26/63) and 1.8% of the high- and low-grade squamous intraepithelial lesions referral cytology cases, respectively. Our data indicate that repeated cytology provides potentially clinically useful information in only a small percentage of overall cases but a substantial proportion of high-grade squamous intraepithelial lesion referral cytology cases, suggesting that high-risk referral cytology case subsets can be defined wherein the routine performance of repeated cytology would be most efficacious.  相似文献   
43.
Apolipoprotein E4 (apoE4), the major genetic risk factor of Alzheimer's disease (AD), is associated with enhanced brain inflammation. Genome-wide gene expression profiling was employed to study the effects of apoE genotype on hippocampal gene expression in LPS-treated mice, transgenic for either apoE4 or the AD benign allele, apoE3. This revealed that the expression of inflammation-related genes following intracerebroventricular injection of LPS was significantly higher and more prolonged in apoE4 than in apoE3 transgenic mice. Clustering analysis revealed gene clusters which responded differently in apoE4 and apoE3 mice and were significantly enriched in NF-kappaB response elements. Direct measurement of NF-kappaB-regulated genes revealed that their extent of activation was greater in the apoE4 mice. Immunohistochemistry experiments revealed that microglial and NF-kappaB activation were more pronounced in apoE4 than in apoE3 mice. These findings suggest that the increased brain inflammation in apoE4 mice is related to disregulation of NF-kappaB signaling pathway.  相似文献   
44.
We report the first case of disseminated Mycobacterium colombiense infection in a solid organ transplant recipient. Co‐infection with Cryptococcus neoformans led to fatal multisystem organ failure. We review the pathogen and host factors contributing to these opportunistic infections.  相似文献   
45.

Background

Eotaxin (CCL11) is a small protein produced in the lungs of patients with asthma, and is a potent chemoattractant for eosinophils.

Aim

To elucidate the role of eotaxin in asthma by an association study of functional and novel eotaxin polymorphisms in case–control and family‐based study designs.

Methods

Eotaxin +67G/A, –384A/G and –426C/T single‐nucleotide polymorphisms and a hexanucleotide (GAAGGA)n repeat 10.9 kb upstream of the gene were genotyped in a cohort of age, sex and ethnically matched patients with asthma (n = 235) and healthy controls (n = 239), and also in a study population of 230 families with asthma recruited from north/northwest India. Total serum IgE (TsIgE) and plasma eotaxin levels were measured using ELISA.

Results

+67G/A polymorphism was found to be significantly associated with asthma in case–control (p = 0.009) and family‐based studies (p = 0.006). Its functional role, as it was correlated with plasma eotaxin levels (p = 0.006), was also demonstrated. Further, –384C/T single‐nucleotide polymorphism was found to be significantly associated with log10 TsIgE (p = 0.016 in case–control and p = 0.018 in families) and eotaxin levels (p = 0.007). Most interestingly, for the first time, a highly significant association of the newly studied (GAAGGA)n hexanucleotide repeat with asthma (p = 3×10−6), log10TsIgE (p = 0.006) and eotaxin levels (p = 0.004) was observed. G_A_C_8 was also identified as an important risk haplotype associated with high TsIgE and plasma eotaxin levels.

Conclusions

This study provides further evidence that eotaxin polymorphisms are associated with the development of asthma by regulating eotaxin levels and reinforces towards the scanning of other chemokine genes present at 17q21 locus for their association with asthma and related phenotypes.Eosinophils play a major role in the pathogenesis of allergic diseases including asthma by releasing various granular proteins, reactive NO, cytokines and chemokines at the site of inflammation, thus causing tissue damage.1 Interplay between chemokines and their receptors are considered to be crucial for the trafficking of eosinophil and other lymphocytes from the circulation to the bronchoalveolar spaces of the patients with asthma.2 Eotaxin (chemokine, CC motif, ligand; CCL11) is a predominant eosinophil chemoattractant, which binds to chemokine receptor 3.3,4 Chemokine receptor 3 is also present on the Th2 CD4+ lymphocytes, basophils, dendritic cells and mast cells.5,6 Thus, the role of eotaxin in asthma is not confined to eosinophil migration and activation only, but extended to many other effector cells involved in disease pathogenesis. It has also been observed that along with interleukin 5, eotaxin prolongs the viability of eosinophils.7 Eotaxin mRNA and protein are found to be elevated in the induced sputum, bronchial epithelium and airways of the patients with moderate to severe asthma.8,9,10 Bronchoalveolar lavage fluid of the patients with asthma also showed increased levels of eotaxin after allergen inhalation.11 In addition, higher plasma eotaxin levels have been observed in subjects with symptoms of acute asthma and airflow obstruction than subjects with stable asthma. Plasma eotaxin levels have been correlated with severity of asthma even in the presence of steroid treatment.12,13Eotaxin gene is present on chromosome 17q21.1, where linkage with asthma and related phenotypes has been previously reported in various ethnic populations.14,15 Previous studies on eotaxin gene polymorphisms and asthma remain inconclusive as most of them failed to establish a strong association.16,17,18,19,20 However, in few other studies, eotaxin single‐nucleotide polymorphisms (SNPs) have been correlated significantly with asthma‐associated phenotypes including lung function, serum IgE, circulating blood eosinophils, eosinophil migration and activation, and plasma eotaxin levels.16,17,18,21,22 Studies have also been undertaken to demonstrate the functional implication of various promoter and exonic variants of the eotaxin.20,22 Notably, the variant and the direction of association are inconsistent across different ethnic populations owing to some inherent reasons. However, no such studies have yet been undertaken in an ethnically divergent Indian population.Importantly, the 17q11–17q21 chromosomal region harbours many other important chemokines including RANTES, MCP1, MCP3 and so on, and also the gene for inducible nitric oxide synthase. Recently, we have reported the association of the gene for inducible nitric oxide synthase microsatellite repeats with asthma and related phenotypes in an Indian population, demonstrating the importance of 17q region in asthma predisposition.23 The results of our previous study and the well‐documented role of eotaxin in asthma prompted us to undertake an association study of eotaxin gene with asthma and associated phenotypes in case–control and family‐based study designs. We have also measured the plasma eotaxin level and attempted to correlate it with eotaxin gene variants.  相似文献   
46.
Oxacillin-resistant Staphylococcus aureus (ORSA) is a virulent pathogen responsible for both health care-associated and community onset disease. We used SmaI-digested genomic DNA separated by pulsed-field gel electrophoresis (PFGE) to characterize 957 S. aureus isolates and establish a database of PFGE patterns. In addition to PFGE patterns of U.S. strains, the database contains patterns of representative epidemic-type strains from the United Kingdom, Canada, and Australia; previously described ORSA clonal-type isolates; 13 vancomycin-intermediate S. aureus (VISA) isolates, and two high-level vancomycin-resistant, vanA-positive strains (VRSA). Among the isolates from the United States, we identified eight lineages, designated as pulsed-field types (PFTs) USA100 through USA800, seven of which included both ORSA and oxacillin-susceptible S. aureus isolates. With the exception of the PFT pairs USA100 and USA800, and USA300 and USA500, each of the PFTs had a unique multilocus sequence type and spa type motif. The USA100 PFT, previously designated as the New York/Tokyo clone, was the most common PFT in the database, representing 44% of the ORSA isolates. USA100 isolates were typically multiresistant and included all but one of the U.S. VISA strains and both VRSA isolates. Multiresistant ORSA isolates from the USA200, -500, and -600 PFTs have PFGE patterns similar to those of previously described epidemic strains from Europe and Australia. The USA300 and -400 PFTs contained community isolates resistant only to beta-lactam drugs and erythromycin. Noticeably absent from the U.S. database were isolates with the previously described Brazilian and EMRSA15 PFGE patterns. These data suggest that there are a limited number of ORSA genotypes present in the United States.  相似文献   
47.
ATRX is a SWI/SNF-like chromatin remodeling protein mutated in several X-linked mental retardation syndromes. Gene inactivation studies in mice demonstrate that ATRX is an essential protein and suggest that patient mutations likely retain partial activity. ATRX associates with the nuclear matrix, pericentromeric heterochromatin, and promyelocytic leukemia nuclear bodies (PML-NBs) in a speckled nuclear staining pattern. Here, we used GFP-ATRX fusion proteins to identify the specific domains of ATRX necessary for subnuclear targeting and the effect of patient mutations on this localization. We identified two functional nuclear localization signals (NLSs) and two domains that target ATRX to nuclear speckles. One of the latter domains is responsible for targeting ATRX to PML-NBs. Surprisingly, this domain encompassed motifs IV-VI of the SNF2 domain suggesting that in addition to chromatin remodeling, it may also have a role in subnuclear targeting. More importantly, four different patient mutations within this domain resulted in an approximately 80% reduction in the number of transfected cells with ATRX nuclear speckles and PML colocalization. These results demonstrate that patient mutations have a dramatic effect on subnuclear targeting to PML-NBs. Moreover, these findings support the hypothesis that ATRX patient mutations represent functional hypomorphs and suggest that loss of proper targeting to PML-NBs is an important contributor to the pathogenesis of the ATR-X syndrome.  相似文献   
48.

Background

The use of mobile phone technologies for health promotion and disease prevention has advanced rapidly in recent years. Text4baby is a theory-based mobile health (mHealth) program in which text messages are delivered to pregnant women and new mothers to improve their health care beliefs and behaviors and improve health status and clinical outcomes. Recent evaluations of Text4baby have found that it improves targeted health attitudes and beliefs, but effects on behavior have not yet been determined.

Objective

In this study, investigators aimed to evaluate Text4baby in the military women’s population.

Methods

Investigators conducted a randomized controlled trial at Madigan Army Medical Center in Tacoma, Washington, from December 2011 through September 2013. All participants were pregnant women first presenting for care at Madigan. Investigators conducted a baseline assessment using a 24-item, self-administered online survey of attitudes and behaviors related to Text4baby message content. Participants were randomized to Text4baby plus usual care (intervention) or usual care alone (control). Investigators analyzed treatment effects of Text4baby on short-term targeted outcomes 4 weeks post enrollment.

Results

For this study, 943 patients were randomized and completed a baseline assessment. The average patient age was 28 years and nearly 70% self-identified as Caucasian. 48.7% of enrollees (459/943) completed the first follow-up assessment. Higher rates of single and working/in-school patients dropped out of the intervention arm of the study, and we adjusted for this finding in subsequent models. However, while investigators were unable to re-survey these participants, only 1.9% of Text4baby enrollees (18/943) dropped the service during the study period. Adjusted and unadjusted logistic generalized estimating equation models were developed to assess intervention effects on measured outcomes. In the model adjusting for age, marital status, having had a previous baby, and race/ethnicity, there was a significant effect of Text4baby intervention exposure on increased agreement with belief in the importance of taking prenatal vitamins (OR 1.91, 95% CI 1.08-3.34, P=.024). All of these attitudes had been targeted by at least one text message during the 4-week evaluation period examined in this study. In unadjusted models, there was a significant effect of intervention exposure on belief in the importance of visiting a health care provider to be a healthy new mother (OR 1.52, 95% CI 1.01-2.31, P=.046) and in the health risks of alcohol during pregnancy (OR 2.06, 95% CI 1.00-4.31, P=.05). No behavioral effects of the intervention were observed in this analysis.

Conclusions

Text4baby is a promising program that offers lessons for future mHealth activities. This large-scale study demonstrated initial effects of the program on attitudes and beliefs targeted by the messages received by women during the study period. Results confirm previous findings from Text4baby studies and other mHealth research. Future analyses will examine dosage effects of the intervention on behaviors and clinical outcomes.  相似文献   
49.
Because epithelial cells are the major cell type productively infected with Chlamydia during genital tract infections, the overall goal of our research was to understand the contribution of infected epithelial cells to the host defense. We previously showed that Toll-like receptor 3 (TLR3) is the critical pattern recognition receptor in oviduct epithelial (OE) cells that is stimulated during Chlamydia infection, resulting in the synthesis of beta interferon (IFN-β). Here, we present data that implicates TLR3 in the expression of a multitude of other innate-inflammatory immune modulators including interleukin-6 (IL-6), CXCL10, CXCL16, and CCL5. We demonstrate that Chlamydia-induced expression of these cytokines is severely disrupted in TLR3-deficient OE cells, whereas Chlamydia replication in the TLR3-deficient cells is more efficient than in wild-type OE cells. Pretreatment of the TLR3-deficient OE cells with 50 U of IFN-β/ml prior to infection diminished Chlamydia replication and restored the ability of Chlamydia infection to induce IL-6, CXCL10, and CCL5 expression in TLR3-deficient OE cells; however, CXCL16 induction was not restored by IFN-β preincubation. Our findings were corroborated in pathway-focused PCR arrays, which demonstrated a multitude of different inflammatory genes that were defectively regulated during Chlamydia infection of the TLR3-deficient OE cells, and we found that some of these genes were induced only when IFN-β was added prior to infection. Our OE cell data implicate TLR3 as an essential inducer of IFN-β and other inflammatory mediators by epithelial cells during Chlamydia infection and highlight the contribution of TLR3 to the inflammatory cytokine response.  相似文献   
50.
Conventional indirect drug susceptibility testing of Mycobacterium tuberculosis with liquid medium is well established and offers time-saving and reliable results. This multicenter study was carried out to evaluate if drug susceptibility testing (DST) can be successfully carried out directly from processed smear-positive specimens (direct DST) and if this approach could offer substantial time savings. Sputum specimens were digested, decontaminated, and concentrated by the laboratory routine procedure and were inoculated in Bactec MGIT 960 as well as Lowenstein-Jensen (LJ) medium for primary isolation. All the processed specimens which were acid-fast bacterium (AFB) smear positive were used for setting up direct DST for isoniazid (INH) and rifampin (RIF). After the antimicrobial mixture of polymyxin B, amphotericin B, nalidixic acid, trimethoprim, and azlocillin (PANTA) was added, the tubes were entered in the MGIT 960 instrument using the 21-day protocol (Bactec 960 pyrazinamide [PZA] protocol). Results obtained by direct DST were compared with those obtained by indirect DST to establish accuracy and time savings by this approach. Of a total of 360 AFB smear-positive sputum specimens set up for direct DST at four sites in three different countries, 307 (85%) specimens yielded reportable results. Average reporting time for direct DST was 11 days (range, 10 to 12 days). The average time savings by direct DST compared to indirect DST, which included time to isolate a culture and perform DST, was 8 days (range, 6 to 9 days). When results of direct DST were compared with those of indirect DST, there was 95.1% concordance with INH and 96.1% with rifampin. These findings indicate that direct DST with the Bactec MGIT 960 system offers further time savings and is a quick method to reliably detect multidrug resistance (MDR) cases.  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