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   164篇
  免费   18篇
  2021年   2篇
  2020年   1篇
  2019年   1篇
  2018年   5篇
  2017年   6篇
  2016年   3篇
  2015年   6篇
  2014年   4篇
  2013年   10篇
  2012年   11篇
  2011年   6篇
  2010年   3篇
  2009年   5篇
  2008年   9篇
  2007年   5篇
  2006年   10篇
  2005年   4篇
  2004年   2篇
  2003年   6篇
  2002年   5篇
  2001年   1篇
  2000年   6篇
  1999年   7篇
  1998年   7篇
  1997年   2篇
  1996年   1篇
  1995年   4篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   3篇
  1990年   2篇
  1989年   2篇
  1988年   3篇
  1987年   5篇
  1986年   5篇
  1985年   4篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1980年   2篇
  1978年   1篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1972年   2篇
  1969年   1篇
  1948年   1篇
排序方式: 共有182条查询结果,搜索用时 78 毫秒
81.
82.
83.
We present a first evaluation of the results of the GRECO project which aims to conceive and realise an innovative device for ocular surgery by ultrafast pulse laser optimised for corneal grafting.  相似文献   
84.
In the present study, the prognostic impact of factors involved in the apoptosis pathway were tested on 67 consecutive patients treated with surgical resection. Included in the study were all patients resected for pancreatic adenocarcinoma from 1988 to 2003. Expression analysis for p53, Bax, and Bcl-2 were performed by immunohistochemical staining. Apoptotic cells were identified by the TUNEL method. These data were correlated with survival. Sixty-seven tumor specimens were included in the study. A strong positive correlation was recorded between p53 overexpression and Bax expression levels (P < 0.001). By univariate analysis, overall survival seemed to be improved with Bcl-2 and Bax expression (respectively, P = 0.0379 and 0.0311). The median survival time in patients with low apoptotic index was better versus those with a high index (P = 0.0127). Lymph node involvement was the only clinico-pathologic parameter that significantly correlated with overall survival (P = 0.0202). By a multivariate Cox regression analysis, the only immunohistochemical parameter that influenced overall survival was the apoptotic index (P = 0.040). Tumor's overexpression of both Bax and Bcl-2 resulted the strongest independent prognostic factor (P = 0.013). This is the first study to report a statistically significant association of apoptosis to overall survival for pancreatic cancer patients treated with surgical resection. The contemporary overexpression of Bax and Bcl-2 represents the strongest prognostic factor.  相似文献   
85.

Background

Female genital tuberculosis is an uncommon disease that is rarely diagnosed in developed countries.

Case presentation

A 61-year-old postmenopausal woman who had undergone surgery and treated with adjuvant chemotherapy for infiltrating ductal carcinoma of the breast five years ago, presented with bloody vaginal discharge, fatigue, weight loss, and low grade fevers at night for two months. Histological examination of the endometrium, done based on the suspicion of a second primary cancer due to the tamoxifen therapy, revealed a granulomatous reaction. Liquid and solid mycobacterial cultures of the tissues were performed. Although the acid fast staining was negative, the liquid culture was positive for Mycobacterium tuberculosis. Involvement of other systems was not detected. The patient was treated with a three-drug antituberculosis regimen for 9 months and recovered fully.

Conclusion

Female genital tuberculosis is a rare but curable disease that should be included in the differential diagnosis of women with menstrual problems. Early diagnosis is important and may prevent unnecessary invasive procedures for the patient.  相似文献   
86.
In addition to providing potable drinking water, U.S. water systems are critical to the maintenance of many vital public services, such as fire suppression and power generation. Disruption of these systems would produce severe public health and safety risks, as well as considerable economic losses. Thus, water systems have been designated as critical to national security by the U.S. government. Previous outbreaks of waterborne disease have demonstrated the vulnerability of both the water supply and the public's health to biological contamination of drinking water. Such experiences suggest that a biological attack, or even a credible threat of an attack, on water infrastructure could seriously jeopardize the public's health, its confidence, and the economic vitality of a community. Despite these recognized vulnerabilities, protecting water supplies from a deliberate biological attack has not been sufficiently addressed. Action in this area has suffered from a lack of scientific understanding of the true vulnerability of water supplies to intentional contamination with bioweapons, insufficient tools for detecting biological agents, and a lack of funds to implement security improvements. Much of what is needed to address the vulnerability of the national water supply falls outside the influence of individual utilities. This includes developing a national research agenda to appropriately identify and characterize waterborne threats and making funds available to implement security improvements.  相似文献   
87.
The limits of maximizing the open‐circuit voltage Voc in solar cells based on poly[2,7‐(9,9‐didecylfluorene)‐alt‐5,5‐(4,7‐di‐2‐thienyl‐2,1,3‐benzothiadiazole)] (PF10TBT) as a donor using different fullerene derivatives as acceptor are investigated. Bulk heterojunction solar cells with PF10TBT and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) give a Voc over 1 V and a power conversion efficiency of 4.2%. Devices in which PF10TBT is blended with fullerene bisadduct derivatives give an even higher Voc, but also a strong decrease in short circuit current (Jsc). The higher Voc is attributed to the higher LUMO of the acceptors in comparison to PCBM. By investigating the photophysics of PF10TBT:fullerene blends using near‐IR photo‐ and electroluminescence, time‐resolved photoluminescence, and photoinduced absorption we find that the charge transfer (CT) state is not formed efficiently when using fullerene bisadducts. Hence, engineering acceptor materials with a LUMO level that is as high as possible can increase Voc, but will only provide a higher power conversion efficiency, when the quantum efficiency for charge transfer is preserved. To quantify this, we determine the CT energy (ECT) and optical band gap (Eg), defined as the lowest first singlet state energy ES1 of either the donor or acceptor, for each of the blends and find a clear correlation between the free energy for photoinduced electron transfer and Jsc. We find that Eg ? qVoc > 0.6 eV is a simple, but general criterion for efficient charge generation in donor‐acceptor blends.  相似文献   
88.
The objective of the present study was to evaluate whether placental mesenchymal stromal cells (PDMSCs) derived from normal and preeclamptic (PE) chorionic villous tissue presented differences in their cytokines expression profiles. Moreover, we investigated the effects of conditioned media from normal and PE-PDMSCs on the expression of pro-inflammatory Macrophage migration Inhibitory Factor (MIF), Vascular Endothelial Growth Factor (VEGF), soluble FMS-like tyrosine kinase-1 (sFlt-1) and free β-human Chorionic Gonadotropin (βhCG) by normal term villous explants. This information will help to understand whether anomalies in PE-PDMSCs could cause or contribute to the anomalies typical of preeclampsia.

Methods

Chorionic villous PDMSCs were isolated from severe preeclamptic (n = 12) and physiological control term (n = 12) placentae. Control and PE-PDMSCs’s cytokines expression profiles were determined by Cytokine Array. Control and PE-PDMSCs were plated for 72 h and conditioned media (CM) was collected. Physiological villous explants (n = 48) were treated with control or PE-PDMSCs CM for 72 h and processed for mRNA and protein isolation. MIF, VEGF and sFlt-1 mRNA and protein expression were analyzed by Real Time PCR and Western Blot respectively. Free βhCG was assessed by immunofluorescent.

Results

Cytokine array showed increased release of pro-inflammatory cytokines by PE relative to control PDMSCs. Physiological explants treated with PE-PDMSCs CM showed significantly increased MIF and sFlt-1 expression relative to untreated and control PDMSCs CM explants. Interestingly, both control and PE-PDMSCs media induced VEGF mRNA increase while only normal PDMSCs media promoted VEGF protein accumulation. PE-PDMSCs CM explants released significantly increased amounts of free βhCG relative to normal PDMSCs CM ones.

Conclusions

Herein, we reported elevated production of pro-inflammatory cytokines by PE-PDMSCs. Importantly, PE PDMSCs induced a PE-like phenotype in physiological villous explants. Our data clearly depict chorionic mesenchymal stromal cells as central players in placental physiopathology, thus opening to new intriguing perspectives for the treatment of human placental-related disorders as preeclampsia.  相似文献   
89.
Biological Invasions - Forests in eastern North America are experiencing high densities of white-tailed deer (Odocoileus virginianus) and encroachment by invasive plants, both of which threaten...  相似文献   
90.

Purpose

Breast cancer follow-up procedures after primary treatment are still a controversial issue. Aim of this study was to investigate, through a web-based survey, surveillance methodologies selected by Italian oncologists in everyday clinical practice.

Methods

Referents of Italian medical oncology units were invited to participate to the study via e-mail through the SurveyMonkey website. Participants were asked how, in their institution, exams of disease staging and follow-up are planned in asymptomatic women and if surveillance continues beyond the 5th year.

Results

Between February and May 2013, 125 out of 233 (53.6%) invited referents of Italian medical oncology units agreed to participate in the survey. Ninety-seven (77.6%) referents state that modalities of breast cancer follow-up are planned according to the risk of disease progression at diagnosis and only 12 (9.6%) oncology units apply the minimal follow-up procedures according to international guidelines. Minimal follow-up is never applied in high risk asymptomatic women. Ninety-eight (78.4%) oncology units continue follow-up in all patients beyond 5 years.

Conclusions

Our survey shows that 90.4% of participating Italian oncology units declare they do not apply the minimal breast cancer follow-up procedures after primary treatment in asymptomatic women, as suggested by national and international guidelines. Interestingly, about 80.0% of interviewed referents performs the so called “tailored follow-up”, high intensity for high risk, low intensity for low risk patients. There is an urgent need of randomized clinical trials able to determine the effectiveness of risk-based follow-up modalities, their ideal frequency and persistence in time.  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