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   411篇
  免费   12篇
  423篇
  2022年   2篇
  2021年   4篇
  2020年   8篇
  2019年   8篇
  2018年   5篇
  2017年   4篇
  2016年   16篇
  2015年   17篇
  2014年   11篇
  2013年   13篇
  2012年   35篇
  2011年   51篇
  2010年   15篇
  2009年   10篇
  2008年   21篇
  2007年   16篇
  2006年   21篇
  2005年   23篇
  2004年   21篇
  2003年   20篇
  2002年   15篇
  2001年   5篇
  2000年   6篇
  1999年   3篇
  1998年   3篇
  1997年   3篇
  1995年   3篇
  1992年   3篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1988年   5篇
  1987年   3篇
  1986年   3篇
  1985年   2篇
  1984年   2篇
  1983年   3篇
  1975年   2篇
  1973年   3篇
  1971年   1篇
  1970年   6篇
  1969年   4篇
  1968年   1篇
  1967年   2篇
  1966年   1篇
  1965年   4篇
  1962年   1篇
  1960年   1篇
  1959年   1篇
  1958年   1篇
排序方式: 共有423条查询结果,搜索用时 0 毫秒
1.
2.
This study aims at substituting the essential functions of photoreceptors in patients who are blind owing to untreatable forms of hereditary retinal degenerations. A microelectronic neuroprosthetic device, powered via transdermal inductive transmission, carrying 1500 independent microphotodiode-amplifier-electrode elements on a 9 mm2 chip, was subretinally implanted in nine blind patients. Light perception (8/9), light localization (7/9), motion detection (5/9, angular speed up to 35 deg s−1), grating acuity measurement (6/9, up to 3.3 cycles per degree) and visual acuity measurement with Landolt C-rings (2/9) up to Snellen visual acuity of 20/546 (corresponding to decimal 0.037 or corresponding to 1.43 logMAR (minimum angle of resolution)) were restored via the subretinal implant. Additionally, the identification, localization and discrimination of objects improved significantly (n = 8; p < 0.05 for each subtest) in repeated tests over a nine-month period. Three subjects were able to read letters spontaneously and one subject was able to read letters after training in an alternative-force choice test. Five subjects reported implant-mediated visual perceptions in daily life within a field of 15° of visual angle. Control tests were performed each time with the implant''s power source switched off. These data show that subretinal implants can restore visual functions that are useful for daily life.  相似文献   
3.
4.
5.
Human enterovirus 109 (EV109) is a recently identified recombinant enterovirus in family Picornaviridae from acute paediatric respiratory illness in Nicaragua. EV109 have not been reported elsewhere. Our aims were the molecular detection and genetic analysis of EV109 from acute childhood respiratory infections in Hungary. Nasopharyngeal aspirates were collected from children under age of 10 years with acute respiratory infections treated in Department of Pulmonology, Kaposi Mór Teaching Hospital, Mosdós, Hungary. Samples were taken from 15 October to 15 May in two respiratory seasons 2005/2006 and 2006/2007. Samples were tested using EV109 specific VP1 primers by RT-PCR method. One (1.1%) of the 92 nasopharyngeal aspirates was positive for EV109 collected from a 2.5-year-old child in January, 2007. The main symptoms were dropping nose, fever (38.1°C), hard cough and wheezing associated with bronchitis and pneumonia. Based upon the VP1 gene region EV109 (L87/HUN/2007, JN900470) has 93% nucleotide identity and identical recombinant pattern to the prototype EV109. This is the first detection of the novel recombinant enterovirus, EV109, in Hungary (in Europe). This study supports the possibility that EV109 is able to cause acute respiratory infections, in addition, it might be plays a part in lower respiratory disease with hospitalization in children.  相似文献   
6.
Identifying the membrane proteome of HIV-1 latently infected cells   总被引:11,自引:0,他引:11  
Profiling integral plasma membrane proteins is of particular importance for the identification of new biomarkers for diagnosis and for drug development. We report in this study the identification of surface markers by performing comparative proteomics of established human immunodeficiency virus-1 (HIV-1) latent cell models and parental cell lines. To this end we isolated integral membrane proteins using a biotin-directed affinity purification method. Isolated proteins were separated by two-dimensional gel electrophoresis and identified by matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) after in gel digestion. Seventeen different proteins were found to vary on the surface of T-cells due to HIV-1 infection. Of these proteins, 47% were integral membrane proteins, and 18% were membrane-associated. Through the use of complementary techniques such as Western blotting and fluorescent staining, we confirmed the differential expression of some of the proteins identified by MALDI-TOF including Bruton's tyrosine kinase and X-linked inhibitor of apoptosis. Finally, using phosphatidylinositol 3-kinase inhibitors and flavopiridol to inhibit Bruton's tyrosine kinase localization at the membrane and X-linked inhibitor of apoptosis protein expression, respectively, we showed that HIV-1 latently infected cells are more sensitive to these drugs than uninfected cells. This suggests that HIV-1 latently infected cells may be targeted with drugs that alter several pathways that are essential for the establishment and maintenance of latency.  相似文献   
7.
    
Microbial transglutaminase (EC 2.3.2.13) (mTGase) catalyses a calcium-independent acyl-transfer reaction in which -(γ-glutamyl)lysine bonds are formed using the γ-carboxyamide groups of peptide-bound glutamine residues and the amino group of lysine side-chains. Here we present a comparative study on alternative lysine and glutamine substitutes in mTGase catalysis. A homologous series of ω-amino acids, serving as lysine substitutes, was incorporated into carbobenzoxy-l-glutaminylglycine (CBZ-Gln-Gly). The rate constants and particular conversion rates increased with increasing chain length. As for the glutamine substitutes, adipic diamide, glutaric monoamide, and glutaric diamide were converted with monodansylcadaverine (DNS-cadaverine) under mTGase catalysis. For the synthetic glutamine substitutes, the substrates of natural chain length, glutaric mono- and diamide, are better converted than the longer adipic diamide indicating that the window of opportunity seems to be smaller. Synthetic substrates, serving as amine acceptors, offer new opportunities in the field of transglutaminase-catalysed reactions.  相似文献   
8.
The main problem of craniospinal irradiation (CSI) is the matching of the fields. The use of a suitable technique is very important because matching of the fields is necessary to use for the optimal cancer irradiation of the long planning target volume (PTV). Since 2007, 8 patients have received CT-based, 3D-planned conformal CSI in our Institute. Patient immobilization was made in prone position in a vacuum bed, using skull and pelvis masks. Organ-at-risk (OAR) contours were made by radiographers. PTV was contoured by radiation oncologists. The prescribed dose to the PTV was 36 Gy with 1.8 Gy dose per fraction. In the planning process the following aspects were taken under consideration: all points of the PTV had to receive at least 95% of the prescribed dose (according to ICRU 50, 62); at junction field edges the overlapping parts were eliminated using a multisegmental technique, where the adjacent segment ends of the neighbouring fields were shifted two times 2 cm, so that the three equally weighted segments used in one field had 2-2 cm distance from each other. In the CSI planning the shape of the patient and so the length of the PTV has made a big emphasis on determining the number of field matching. Thus in some cases instead of two, only one field matching was sufficient - this could be achieved by increasing the source-to-skin distance (SSD) of the fields. The verification made with a solid-water phantom justified the precision of the field matching. The offset used at junction field edges in between one treatment facilitates the verification of field matching - and so the patient positioning. Thus the possibility of having overdosed regions could be reduced, which was very important from a radiation biological point of view.  相似文献   
9.
Breast screening programs along with advances in diagnostic methods and oncologic treatment have resulted in full recovery for a decisive number of patients diagnosed with early-stage breast cancer. The results of the ultra-radical-, followed by the breast conserving era pose new opportunities and challenges for the oncologic breast surgeon. The focus of oncoplastic surgery is not only on the tumor, but also on the female patient, allowing for individualized immediate breast reconstruction with acceptable esthetic result following radical tumor exstirpation. Modern procedures differ both in concept and technique from that of traditional breast surgery. This paper provides a comprehensive and detailed overview of reconstructive and oncoplastic breast surgery.  相似文献   
10.
The aim of this study was to evaluate the usefulness of quantitative real-time PCR (RQ-PCR) for the monitoring of molecular remission in follicular lymphoma (FL) patients during long-term follow-up. RQ-PCR by the use of TaqMan detection system is a sensitive tool to monitor minimal residual disease (MRD) in FL through amplification of the t(14;18) fusion gene during and post-therapy. In most cases the breakpoint region occurs within the major breakpoint region (MBR). Among 75 patients diagnosed with FL, cells harboring the fusion gene BCL2/JH were found in peripheral blood of 31 patients (41%). We further monitored 30 of these patients in a period varying from 6 months to 5 years by RQ-PCR. In our study the level indicating the possibility of the presence of MRD was established at more than five t(14;18)-positive cells in the background of 83,000 normal cells. The results of this work also confirmed that the presence of MRD detected by RQ-PCR is an indication for careful observation of patients because of a higher risk of disease recurrence.  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