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   251篇
  免费   7篇
儿科学   2篇
妇产科学   1篇
基础医学   47篇
口腔科学   1篇
临床医学   20篇
内科学   41篇
皮肤病学   2篇
神经病学   6篇
特种医学   1篇
外科学   24篇
预防医学   26篇
眼科学   1篇
药学   19篇
中国医学   1篇
肿瘤学   66篇
  2023年   2篇
  2021年   8篇
  2020年   2篇
  2019年   8篇
  2018年   3篇
  2017年   2篇
  2016年   7篇
  2015年   4篇
  2014年   6篇
  2013年   11篇
  2012年   10篇
  2011年   12篇
  2010年   6篇
  2009年   4篇
  2008年   8篇
  2007年   8篇
  2006年   22篇
  2005年   9篇
  2004年   14篇
  2003年   10篇
  2002年   8篇
  2001年   8篇
  2000年   9篇
  1999年   11篇
  1997年   3篇
  1996年   5篇
  1995年   3篇
  1994年   5篇
  1992年   6篇
  1991年   2篇
  1990年   3篇
  1988年   2篇
  1987年   3篇
  1986年   3篇
  1985年   4篇
  1984年   2篇
  1983年   2篇
  1982年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   3篇
  1975年   2篇
  1974年   4篇
  1973年   1篇
  1972年   2篇
  1970年   1篇
  1969年   1篇
  1968年   2篇
  1966年   2篇
排序方式: 共有258条查询结果,搜索用时 203 毫秒
1.
Alcohol and other drug (AOD) use behaviors of health professions students (HPS) were assessed by surveying both university-based HPS and other nursing programs in a Midwestern state in 1999. Response was 2,646 (56.4%) of surveyed students. Family history of alcohol-related and drug-related problems were reported by 39.8% and 13.9%, respectively, with 42.6% of respondents reporting one or both. Among nursing respondents, 48.1%, 19.2% and 51.1%, respectively, reported family problems with alcohol, drugs, or one or both. Past-year alcohol use was comparable to undergraduate college students (UCS) nationally (83%); heavy drinking, tobacco and recreational drug use by HPS were lower. Past year drug use was highest among medical students. Marijuana was the predominant illicit drug; medical students and males most often reported use. Health professions educational systems should proactively address student AOD prevention, education and assistance needs.  相似文献   
2.
Thoracoscopic Retrieval of Foreign Bodies After Penetrating Chest Trauma   总被引:1,自引:0,他引:1  
Video-assisted thoracic surgery or thoracoscopy has proved to be valuable in many settings in thoracic surgery. The use of video-assisted thoracic surgery in trauma has been limited, especially with respect to penetrating trauma. We report the use of thoracoscopy to remove intrathoracic fragments of glass and avert the need for a thoracotomy.  相似文献   
3.
Deregulated cell cycle and defective genome-integrity checkpoints are among the hallmarks of cancer.Here we summarize our recent studies of key components of the GI/S machinery in normal human spermatogenesis, and their abnormalities in testicular germ cell tumours (TGCTs), with special emphasis on carcinoma in situ lesions (CIS). Our combined immunohistochemical and immunoblotting analyses of normal human adult and fetal testes, CIS, seminomas, embryonal carcinomas, and teratomas, revealed an 'unorthodox' spectrum of defects within the so-called RB pathway in TGCTs. The early aberrations included lack of expression of the retinoblastoma tumour suppressor (pRB) and the CDK inhibitor pl9ink4d, and overexpression of cyclin D2. Progression from CIS to invasive TGCTswas associated with loss of another two CDK inhibitors and tumour suppressors: pl6ink4a and pl8ink4c. We also found the lack of pRB and pl9ink4d in fetal gonocytes, the candidate target cell for all types of TGCTs. These findings, together with the status of the Chk2-p53 DNA-integrity checkpoint, are considered in relation to the origin, biology and pathogenesis of TGCTs, and potential implications of the GI/S defects for the curability of these tumours.  相似文献   
4.
Seventy-two samples of infant breasts, aged from newborn to 2 years, were collected at necropsy. Whole-mount preparations and histological sections were made. A system of classification was devised to study the extent of the structural development of the ductal system (morphological types I, II, and III) and the functional differentiation of the lining epithelium (functional stages I to V). There was no correlation between the age of the infant and the type of development of the ductal system. In contrast, the epithelial differentiation followed a chronological pattern, starting with secretory changes and apparently going through a period characterized by apocrine metaplasia before post-secretory involution. These epithelial changes were not associated with the morphological type of the ductal system. There were no distinguishing features between the breasts from the two sexes. Immunoperoxidase staining for actin and kappa-casein was carried out to study the myoepithelial cells and secretory cells, respectively. Myoepithelial cells were present at all stages and prominent staining for casein was observed up to 2 months of age. Embryonic-type adipose tissue was seen in 7 cases, in one of which it was associated closely with the developing ductal system. Extramedullary hematopoiesis was observed in the periductal connective tissue until 4 months of age. This paper describes the most extensive anatomical and histological study of the human infant breast to date and lays the foundation for a detailed study of the epithelial and stromal changes that take place during human breast development.  相似文献   
5.
Prolonged excitation of fluorescent probes leads eventually to loss of their capacity to emit light. A decrease in the number of detected photons reduces subsequently the resolving power of a fluorescence microscope. Adverse effects of fluorescence intensity loss on the quality of microscopic images of biological specimens have been recognized, but not determined quantitatively. We propose three human-independent methods of quality determination. These techniques require no reference images and are based on calculation of the actual resolution distance, information entropy, and signal-to-noise ratio (SNR). We apply the three measures to study the effect of photobleaching in cell nuclei stained with propidium iodide (PI) and chromomycin A3 (CA3) and imaged with fluorescence confocal microscopy. We conclude that the relative loss of image quality is smaller than the corresponding decrease in fluorescence intensity. Furthermore, the extent of quality loss is related to the optical properties of the imaging system and the noise characteristics of the detector. We discuss the importance of these findings for optimal registration and compression of biological images.  相似文献   
6.
The perforin (PFN) protein is essential for the elimination of target cells by cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. The study of cells releasing PFN has been hampered by a lack of sensitive methods. We therefore produced PFN-reactive monoclonal antibodies (mAb) and developed capture enzyme-linked immunosorbent (ELISA) and enzyme-linked immunospot (ELISpot) assays. Three mAbs were generated and shown to react with unique determinants of PFN. All mAbs recognized intracellular PFN in human peripheral blood mononuclear cell (PBMC) as assessed by flow cytometry and immunohistochemistry. Functional PFN capture ELISA and ELISpot assays were developed utilizing two of the mAbs for capture and the third mAb for detection. When examining PFN release by the YT lymphoma cell line, the ELISpot displayed a greater detection sensitivity than the ELISA. Assessment of PFN release by a CTL clone using ELISpot gave results consistent with a parallel (51)Cr-release cytotoxicity assay. Moreover, PFN release by PBMC could be quantified by ELISpot and ELISA after ex vivo stimulation with defined CTL epitopes from common viruses. These novel immunoassays will be valuable for further investigations of the mechanisms underlying granule-mediated apoptosis. In addition, the capture immunoassays could provide tools for studying CTL responses in infectious and tumor diseases as well as for vaccine development.  相似文献   
7.
8.
9.
A 53 year old patient was hospitalized because of retrosternal oppression which was unrelated to effort and recurred in the early morning hours. An esophageal diverticulum and a hiatal hernia were found. The patient had complaints in spite of medical therapy and an operation was performed because of his oesophageal disorders. After operation the patient had the same pain. A cardiologist was asked, who suggested Prinzmetal variant angina. During arteriography coronary artery disease was found. Coronary bypass surgery was indicated and performed, after that procedure the patient was and remained free of any complaints. This observation reaffirmed Prinzmetal original statement "The key to the diagnosis ... is the taking of a painstaking history".  相似文献   
10.
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