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   341篇
  免费   19篇
  2023年   2篇
  2022年   5篇
  2021年   8篇
  2020年   3篇
  2019年   4篇
  2018年   7篇
  2017年   6篇
  2016年   6篇
  2015年   16篇
  2014年   23篇
  2013年   24篇
  2012年   32篇
  2011年   35篇
  2010年   25篇
  2009年   20篇
  2008年   23篇
  2007年   17篇
  2006年   19篇
  2005年   16篇
  2004年   11篇
  2003年   9篇
  2002年   7篇
  2001年   4篇
  2000年   2篇
  1999年   1篇
  1998年   7篇
  1997年   3篇
  1996年   4篇
  1995年   3篇
  1994年   2篇
  1993年   1篇
  1991年   1篇
  1989年   1篇
  1987年   2篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有360条查询结果,搜索用时 843 毫秒
21.
Background/ObjectivesIn vitro studies have shown that dengue virus (DENV) can thwart the actions of interferon (IFN)-α/β and prevent the development of an antiviral state in infected cells. Clinical studies looking at gene expression in patients with severe dengue show a reduced expression of interferon stimulated genes compared to patients with dengue fever. Interestingly, there are conflicting reports as to the ability of DENV or other flaviviruses to inhibit IFN-α/β signaling.ConclusionsThe ability of DENVs to inhibit IFN-α/β signaling is conserved. Although some variation in the inhibition was observed, the moderate differences may be difficult to correlate with clinical outcomes. DENVs were unable to inhibit pSTAT1 in NHP cell lines, but their ability to inhibit pSTAT1 in primary Rhesus macaque dendritic cells suggests that this may be a cell specific phenomena or due to the transformed nature of the cell lines.  相似文献   
22.

Background

Belgium’s law on euthanasia allows only physicians to perform the act. We investigated the involvement of nurses in the decision-making and in the preparation and administration of life-ending drugs with a patient’s explicit request (euthanasia) or without an explicit request. We also examined factors associated with these deaths.

Methods

In 2007, we surveyed 1678 nurses who, in an earlier survey, had reported caring for one or more patients who received a potential life-ending decision within the year before the survey. Eligible nurses were surveyed about their most recent case.

Results

The response rate was 76%. Overall, 128 nurses reported having cared for a patient who received euthanasia and 120 for a patient who received life-ending drugs without his or her explicit request. Respectively, 64% (75/117) and 69% (81/118) of these nurses were involved in the physician’s decision-making process. More often this entailed an exchange of information on the patient’s condition or the patient’s or relatives’ wishes (45% [34/117] and 51% [41/118]) than sharing in the decision-making (24% [18/117] and 31% [25/118]). The life-ending drugs were administered by the nurse in 12% of the cases of euthanasia, as compared with 45% of the cases of assisted death without an explicit request. In both types of assisted death, the nurses acted on the physician’s orders but mostly in the physician’s absence. Factors significantly associated with a nurse administering the life-ending drugs included being a male nurse working in a hospital (odds ratio [OR] 40.07, 95% confidence interval [CI] 7.37–217.79) and the patient being over 80 years old (OR 5.57, 95% CI 1.98–15.70).

Interpretation

By administering the life-ending drugs in some of the cases of euthanasia, and in almost half of the cases without an explicit request from the patient, the nurses in our study operated beyond the legal margins of their profession.Medical end-of-life decisions with a possible or certain life-shortening effect occur often in end-of-life care.15 The most controversial and ethically debated medical practice is that in which drugs are administered with the intention of ending the patient’s life, whether at the patient’s explicit request (euthanasia) or not. The debate focuses mainly on the role and responsibilities of the physician.6 However, physicians worldwide have reported that nurses are also involved in these medical practices, mostly in the decision-making and sometimes in the administration of the life-ending drugs.13,79 Critical care,10 oncology11 and palliative care nurses12,13 have confirmed this by reporting their own involvement, particularly in cases of euthanasia.14,15In Belgium, the law permits physicians to perform euthanasia under strict requirements of due care, one of which is that they must discuss the request with the nurses involved.16 There are no further explicit stipulations determining the role of nurses in euthanasia. Physician-assisted death is legally regulated in some other countries as well (e.g., the Netherlands, Luxemburg and the US states of Oregon and Washington State), without specifying the role of nurses. Reports from nurses in these jurisdictions are scarce, apart from some that are limited to particular settings, or lack details about their involvement.13,14We conducted this study to investigate the involvement of nurses in Flanders, Belgium, in the decision-making and in the preparation and administration of life-ending drugs with, or without, a patient’s explicit request. We also examined patient- and nurse-related factors associated with the involvement of nurses in these deaths. In a related research article, Chambaere and colleagues describe the findings from a survey of physicians in Flanders about the practices of euthanasia and assisted suicide, and the use of life-ending drugs without an explicit request from the patient.17  相似文献   
23.
24.
The screen of 10 soft coral extracts collected from the Colombian Caribbean Sea in the TPA-induced ear edema model allowed us to identify Eunicea fusca extract among others as an interesting source of active compounds. The new diterpene, fuscoside E (1), along with the known fuscoside B (2), fuscol (3), (+)-germacrene D (4) and a mixture of six sterols (5-10), were isolated from this soft coral. Their structures were elucidated by 1D and 2D NMR spectroscopy techniques. Fuscoside E (1) absolute stereochemistry was determined by chiroptical methods. Fuscoside E (1) and B (2) showed strong anti-inflammatory in the above mentioned bioassay. Additionally, fuscoside E (1) and the sterol mixture (5-10) presented antifouling activity against bacterial strains involved in surface colonization.  相似文献   
25.
Two new compounds, 5-methyl-2-(2-methylbutanoyl)phloroglucinol 1-O-(6-O-β-D-apiofuranosyl)-β-D-glucopyranoside (1) and trans-2,3-dihydrokaempferol 3-O-(4-O-sulfo)-α-L-arabinopyranoside (2), together with 14 known flavonoids, trans-dihydrokaempferol 3-O-α-L-arabinopyranoside (3), trans-taxifolin 3-O-α-L-arabinofuranoside (4), quercetin 3-O-α-L-rhamnopyranoside (5), quercetin 3'-O-α-L-arabinofuranoside (6), catechin 3-O-α-L-rhamnopyranoside (7), trans-taxifolin 3-O-α-L-arabinopyranoside (8), cis-dihydrokaempferol 3-O-α-L-arabinopyranoside (9), catechin (10), myricetin 3-O-α-L-rhamnopyranoside (11), quercetin 3-O-α-L-arabinopyranoside (12), quercetin 3-O-α-L-arabinofuranoside (13), quercetin 3-O-(3″-galloyl)-α-L-rhamnopyranoside (14), quercetin 3-O-(2″-galloyl)-α-L-rhamnopyranoside (15), and epicatechin 3-O-gallate (16), were isolated from the leaves of Ruprechtia polystachya Griseb. (Polygonaceae). Their structures were established on the basis of extensive 1D- and 2D-NMR experiments as well as MS analyses. All compounds, except 1, showed inhibition of the enzyme glucose-6-phosphatase in intact microsomes.  相似文献   
26.
Endothelial cell coverage of blood-contacting devices is crucial to their eventual success in the clinic. Two established human cell lines derived from HUVEC (human umbilical vascular endothelial cells), CRL 2922 and CRL 2873, have been widely utilized to study and model endothelial cell biology. However, it is not clear if these two cell lines would be useful for modeling primary endothelial cell interaction with newly-formulated biomaterials in tissue engineering applications. Hence, this study was conducted to compare the adhesion and proliferation characteristics of HUVEC grown on seven different substrata, tissue culture polystyrene (TCPS), gelatin, chitosan, poly-L-lysine, hyaluronan, poly-L-lactic acid (PLLA), and polylactic-co-glycolic acid (PLGA). The short-term adhesive behavior (2 h) of HUVEC on the various substrata was not closely-replicated by either CRL 2873 or CRL 2922. This was likely because the 2 h timeframe is too short for identification of differences in the interaction among the three cell types grown on various substrata. There was much faster proliferation of CRL 2922 on all seven substrata when compared to HUVEC and CRL 2873. Moreover, the proliferation rates of CRL 2922 on the various substrata showed little variation. In contrast, HUVEC and CRL 2873 displayed similar trends in proliferation rates, with gelatin and TCPS yielding the highest rates, and PLLA and PLGA yielding the lowest rates. Hence, CRL 2873 is better suited for modeling primary endothelial cell interaction with newly-formulated biomaterials than CRL 2922. The advantage of using CRL 2873 over HUVEC for biomaterial screening is that it is immortalized and displays much less inter-batch variability than primary culture.  相似文献   
27.
Alvim E  Ale-Rocha R  Bravo F 《ZooKeys》2011,(125):51-57
The type specimens of Neodiogmites hirtuosus (Wiedemann, 1821), two males and one female, deposited at the Museum für Naturkunde der Humboldt-Universität (ZMHB), Berlin were examined. The specimens show the diagnostic characters of Apoxyria Schiner, 1866: face strongly pronounced, swollen and curved hind tibia, and terminalia with epandrium large and hypandrium short and obtuse. A new combination is suggested, Apoxyria hirtuosa (Wiedemann, 1821), and lectotype and paralectotypes are designated. The species is redescribed, the male terminalia is described and illustrated for the first time, and an identification key to Apoxyria is presented.  相似文献   
28.
29.

Background

The Zimbabwean national prevention of mother-to-child HIV transmission (PMTCT) program provided primarily single-dose nevirapine (sdNVP) from 2002–2009 and is currently replacing sdNVP with more effective antiretroviral (ARV) regimens.

Methods

Published HIV and PMTCT models, with local trial and programmatic data, were used to simulate a cohort of HIV-infected, pregnant/breastfeeding women in Zimbabwe (mean age 24.0 years, mean CD4 451 cells/µL). We compared five PMTCT regimens at a fixed level of PMTCT medication uptake: 1) no antenatal ARVs (comparator); 2) sdNVP; 3) WHO 2010 guidelines using “Option A” (zidovudine during pregnancy/infant NVP during breastfeeding for women without advanced HIV disease; lifelong 3-drug antiretroviral therapy (ART) for women with advanced disease); 4) WHO “Option B” (ART during pregnancy/breastfeeding without advanced disease; lifelong ART with advanced disease); and 5) “Option B+:” lifelong ART for all pregnant/breastfeeding, HIV-infected women. Pediatric (4–6 week and 18-month infection risk, 2-year survival) and maternal (2- and 5-year survival, life expectancy from delivery) outcomes were projected.

Results

Eighteen-month pediatric infection risks ranged from 25.8% (no antenatal ARVs) to 10.9% (Options B/B+). Although maternal short-term outcomes (2- and 5-year survival) varied only slightly by regimen, maternal life expectancy was reduced after receipt of sdNVP (13.8 years) or Option B (13.9 years) compared to no antenatal ARVs (14.0 years), Option A (14.0 years), or Option B+ (14.5 years).

Conclusions

Replacement of sdNVP with currently recommended regimens for PMTCT (WHO Options A, B, or B+) is necessary to reduce infant HIV infection risk in Zimbabwe. The planned transition to Option A may also improve both pediatric and maternal outcomes.  相似文献   
30.
Fidelity of individual animals to breeding sites is a primary determinant of population structure. The degree and scale of philopatry in a population reflect the fitness effects of social facilitation, ecological adaptation and optimal inbreeding. Patterns of breeding-site movement and fidelity are functions of social structure and are frequently sex biased. We report on a female humpback whale (Megaptera novaeangliae) first identified by natural markings off Brazil that subsequently was photographed off Madagascar. The minimum travel distance between these locations is greater than 9800 km, approximately 4000 km longer than any previously reported movement between breeding grounds, more than twice the species' typical seasonal migratory distance and the longest documented movement by a mammal. It is unexpected to find this exceptional long-distance movement between breeding groups by a female, as models of philopatry suggest that male mammals move more frequently or over longer distances in search of mating opportunities. While such movement may be advantageous, especially in changeable or unpredictable circumstances, it is not possible to unambiguously ascribe causality to this rare observation. This finding illustrates the behavioural flexibility in movement patterns that may be demonstrated within a typically philopatric species.  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