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   417篇
  免费   128篇
  545篇
  2023年   4篇
  2022年   6篇
  2021年   14篇
  2020年   10篇
  2019年   11篇
  2018年   11篇
  2017年   11篇
  2016年   18篇
  2015年   16篇
  2014年   24篇
  2013年   22篇
  2012年   37篇
  2011年   26篇
  2010年   17篇
  2009年   21篇
  2008年   33篇
  2007年   54篇
  2006年   123篇
  2005年   28篇
  2004年   12篇
  2003年   16篇
  2002年   8篇
  2000年   2篇
  1999年   4篇
  1998年   6篇
  1997年   2篇
  1994年   3篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1985年   1篇
  1981年   1篇
排序方式: 共有545条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
6.
ObjectiveStress induced hyperglycemia occurs in critically ill patients who have normal glucose tolerance following resolution of their acute illness. The objective was to evaluate the association between stress induced hyperglycemia and incident diabetes in survivors of critical illness.DesignRetrospective cohort study.SettingAll adult patients surviving admission to a public hospital intensive care unit (ICU) in South Australia between 2004 and 2011.PatientsStress induced hyperglycemia was defined as a blood glucose ≥ 11.1 mmol/L (200 mg/dL) within 24 hours of ICU admission. Prevalent diabetes was identified through ICD-10 coding or prior registration with the Australian National Diabetes Service Scheme (NDSS). Incident diabetes was identified as NDSS registration beyond 30 days after hospital discharge until July 2015. The predicted risk of developing diabetes was described as sub-hazard ratios using competing risk regression. Survival was assessed using Cox proportional hazards regression.ConclusionsStress induced hyperglycemia identifies patients at subsequent risk of incident diabetes.  相似文献   
7.

Setting

Private practitioners are frequently the first point of healthcare contact for patients with tuberculosis (TB) in India. Inappropriate TB management practices among private practitioners may contribute to delayed TB diagnosis and generate drug resistance. However, these practices are not well understood. We evaluated diagnostic and treatment practices for active TB and benchmarked practices against International Standards for TB Care (ISTC) among private medical practitioners in Chennai.

Design

A cross-sectional survey of 228 practitioners practicing in the private sector from January 2014 to February 2015 in Chennai city who saw at least one TB patient in the previous year. Practitioners were randomly selected from both the general community and a list of practitioners who referred patients to a public-private mix program for TB treatment in Chennai. Practitioners were interviewed using standardized questionnaires.

Results

Among 228 private practitioners, a median of 12 (IQR 4–28) patients with TB were seen per year. Of 10 ISTC standards evaluated, the median of standards adhered to was 4.0 (IQR 3.0–6.0). Chest physicians reported greater median ISTC adherence than other MD and MS practitioners (score 7.0 vs. 4.0, P<0.001), or MBBS practitioners (score 7.0 vs. 4.0, P<0.001). Only 52% of all practitioners sent >5% of patients with cough for TB testing, 83% used smear microscopy for diagnosis, 33% monitored treatment response, and 22% notified TB cases to authorities. Of 228 practitioners, 68 reported referring all patients with new pulmonary TB for treatment, while 160 listed 27 different regimens; 78% (125/160) prescribed a regimen classified as consistent with ISTC. Appropriate treatment practices differed significantly between chest physicians and other MD and MS practitioners (54% vs. 87%, P<0.001).

Conclusion

TB management practices in India’s urban private sector are heterogeneous and often suboptimal. Private providers must be better engaged to improve diagnostic capacity and decrease TB transmission in the community.  相似文献   
8.
Plant‐soil feedback (PSF) theory provides a powerful framework for understanding plant dynamics by integrating growth assays into predictions of whether soil communities stabilise plant–plant interactions. However, we lack a comprehensive view of the likelihood of feedback‐driven coexistence, partly because of a failure to analyse pairwise PSF, the metric directly linked to plant species coexistence. Here, we determine the relative importance of plant evolutionary history, traits, and environmental factors for coexistence through PSF using a meta‐analysis of 1038 pairwise PSF measures. Consistent with eco‐evolutionary predictions, feedback is more likely to mediate coexistence for pairs of plant species (1) associating with similar guilds of mycorrhizal fungi, (2) of increasing phylogenetic distance, and (3) interacting with native microbes. We also found evidence for a primary role of pathogens in feedback‐mediated coexistence. By combining results over several independent studies, our results confirm that PSF may play a key role in plant species coexistence, species invasion, and the phylogenetic diversification of plant communities.  相似文献   
9.
Background: Rolling-circle replication (RCR) is a novel technology that has not been applied to cell-free DNA (cfDNA) testing until recently. Given the cost and simplicity advantages of this technology compared to other platforms currently used in cfDNA analysis, an assessment of RCR in clinical laboratories was performed. Here, we present the first validation study from clinical laboratories utilizing RCR technology. Methods: 831 samples from spontaneously pregnant women carrying a singleton fetus, and 25 synthetic samples, were analyzed for the fetal risk of trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13), by three laboratories on three continents. All the screen-positive pregnancies were provided post-test genetic counseling and confirmatory diagnostic invasive testing (e.g., amniocentesis). The screen-negative pregnancies were routinely evaluated at birth for fetal aneuploidies, using newborn examinations, and any suspected aneuploidies would have been offered diagnostic testing or confirmed with karyotyping. Results: The study found rolling-circle replication to be a highly viable technology for the clinical assessment of fetal aneuploidies, with 100% sensitivity for T21 (95% CI: 82.35–100.00%); 100.00% sensitivity for T18 (71.51–100.00%); and 100.00% sensitivity for T13 analyses (66.37–100.00%). The specificities were >99% for each trisomy (99.7% (99.01–99.97%) for T21; 99.5% (98.62–99.85%) for T18; 99.7% (99.03–99.97%) for T13), along with a first-pass no-call rate of 0.93%. Conclusions: The study showed that using a rolling-circle replication-based cfDNA system for the evaluation of the common aneuploidies would provide greater accuracy and clinical utility compared to conventional biochemical screening, and it would provide comparable results to other reported cfDNA methodologies.  相似文献   
10.
At the end of spermatogenesis, elongated spermatids are released from supporting Sertoli cells via the process termed spermiation. Previous studies have shown that spermiation failure occurs after hormone suppression, in which spermatids are retained instead of releasing. However, the molecular mechanisms involved in spermiation and spermiation failure are largely unknown. The aims of the present study were, first, to characterize the ultrastructural events associated with normal spermiation and spermiation failure using light and electron microscopy and, second, to investigate the localization of cell adhesion-associated (beta1-integrin and cadherins) and junction-associated molecules (integrin-associated kinase [ILK], beta-catenin, and espin) during these processes. Four adult Sprague-Dawley rats received testosterone and estradiol implants and FSH antibody (2 mg kg-1 day-1) for 7 days to suppress testicular testosterone and FSH and to induce spermiation failure. Four rats treated with saline were used as controls. After testosterone and FSH suppression, spermiation at the ultrastructural level appeared to be normal until the final disengagement of the spermatids from Sertoli cells (stage VIII), at which stage a large number of retained spermatids were noted. Immunohistochemical localization of espin showed that during spermiation, removal of the ectoplasmic specialization (ES) occurred 30 h before spermatid disengagement, suggesting that non-ES junctions mediate the spermatid-Sertoli cell interaction before and during disengagement. beta1-Integrin and beta-catenin remained associated with spermatids after ES removal and until disengagement; however, ILK was removed along with the ES. Though detectable, N-cadherin was not associated with the spermatid-Sertoli cell junction. After testosterone and FSH suppression, beta1-integrin, but not N-cadherin or beta-catenin, remained associated with spermatids that failed to spermiate. In conclusion, hormone suppression-induced spermiation failure is caused by defects in the disengagement of spermatids from the Sertoli cell, and this process likely is mediated by beta1-integrin in an ILK-independent mechanism.  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