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   1206篇
  免费   59篇
  国内免费   16篇
耳鼻咽喉   3篇
儿科学   70篇
妇产科学   27篇
基础医学   111篇
口腔科学   17篇
临床医学   139篇
内科学   294篇
皮肤病学   8篇
神经病学   65篇
特种医学   119篇
外科学   82篇
综合类   32篇
预防医学   133篇
眼科学   17篇
药学   65篇
中国医学   3篇
肿瘤学   96篇
  2020年   14篇
  2019年   10篇
  2018年   15篇
  2017年   15篇
  2016年   15篇
  2015年   14篇
  2014年   31篇
  2013年   35篇
  2012年   46篇
  2011年   45篇
  2010年   29篇
  2009年   26篇
  2008年   31篇
  2007年   27篇
  2006年   34篇
  2005年   32篇
  2004年   33篇
  2003年   35篇
  2002年   36篇
  2001年   28篇
  2000年   25篇
  1999年   29篇
  1998年   36篇
  1997年   24篇
  1996年   23篇
  1995年   20篇
  1994年   23篇
  1993年   20篇
  1992年   27篇
  1991年   27篇
  1990年   32篇
  1989年   50篇
  1988年   42篇
  1987年   34篇
  1986年   36篇
  1985年   49篇
  1984年   23篇
  1983年   17篇
  1982年   15篇
  1981年   16篇
  1980年   13篇
  1979年   30篇
  1978年   12篇
  1977年   8篇
  1976年   12篇
  1975年   12篇
  1974年   9篇
  1973年   11篇
  1972年   8篇
  1970年   9篇
排序方式: 共有1281条查询结果,搜索用时 31 毫秒
1.
2.
3.
Occurrence of the t(2;5)(p23;q35) in non-Hodgkin's lymphoma   总被引:9,自引:3,他引:6  
Primary CD30(Ki-1)-positive anaplastic large-cell lymphoma (ALCL) is considered by some to be a distinct clinicopathologic entity associated with the t(2;5) (p23;q35). However, the specificity of t(2;5) for ALCL has not been carefully studied. Therefore, we performed a detailed analysis of all cases of ALCL with abnormal cytogenetics results in the Nebraska Lymphoma Study Group registry, as well as all other cases of non-Hodgkin's lymphoma with t(2;5) in the registry. We found the t(2;5) in only five of 10 cases of ALCL, four of whom were young patients. However, we also found the t(2;5) in 11 other cases of nonanaplastic lymphoma, including eight children with typical peripheral T-cell lymphomas of various types. The t(2;5) was also found in three older adults with B-cell lymphomas of various types. Thus, the t(2;5) was not specific for CD30+ ALCL. However, t(2;5) may define a clinicopathologic entity in children and young adults characterized by variable morphologies with a T-cell or indeterminate phenotype, CD30-positivity, nodal disease with frequent extranodal involvement, advanced stage, and an excellent response to therapy, including bone marrow transplantation for relapsed disease. The clinical relevance of the t(2;5) in older patients requires further study.  相似文献   
4.
Removing sodium from standard ionic contrastmedia markedly increases the incidence of ventricu-lar fibrillation in patients undergoing coronary arvgiography. Newer nonionic contrast media, Iopa-midol (IOP), Iohexol (IOH) and Ioversol (IOV),contain only trace amounts of sodium. To determinewhether sodium influences the fibrillatory propen-sity of nonionic contrast media, we measured theprolongation in QT interval and performed program-med electrical stimulation with l,2 and 3 ventricularextra stimuli in 40 dogs during 4 ml intracoronaryinjections of IOP, IOH and IOV. Solutions of eachcontrast media with added NaCI at concentrations of0.225To, 0.45% and 0.970 were compared to stockcontrast media. The addition of NaCI markedlyincreased the amount of QT interval prolongationproduced by each contrast media. With IOP, theamount of QT interval prolongation was 40+11msec with standard IOP but was 58+11 msec with0.225'70 NaCI/IOP, 84+17 msec with 0.45'To NaCI/IOP, and 132+42 msec with 0.970 NaCl/IOP(P相似文献   
5.
6.
Winkler  ML; Olsen  WL; Mills  TC; Kaufman  L 《Radiology》1987,165(1):203-207
Two fast magnetic resonance (MR) imaging techniques, advanced Fourier and partial-flip imaging, were used at 0.35 T to examine 21 patients with suspected intracranial lesions; the results were quantitatively compared with a conventional spin-echo study. Both of the fast MR techniques yielded a fourfold reduction in imaging time per section. The advanced Fourier sequence showed contrast that was identical to the conventional spin-echo study with signal-to-noise ratios of 58% and 57% for the first and second echoes, respectively. The partial-flip sequence showed a contrast of 109% and 57% for lesions versus substantia alba, and 107% and 78% for substantia grisea versus substantia alba relative to the first and second echoes of the conventional spin-echo study. The partial-flip sequence was particularly sensitive to magnetic susceptibility; this produced artifacts that may undermine the usefulness of partial flip for routine screening in certain parts of the brain. However, this susceptibility significantly improved the detection of intracranial hemorrhage when compared with the spin-echo sequence, particularly when combined with phase mapping of the partial-flip study.  相似文献   
7.
Pediatric nutrition surveillance system--United States, 1980-1991.   总被引:1,自引:0,他引:1  
The CDC Pediatric Nutrition Surveillance System (PedNSS) monitors the general health and nutritional characteristics of low-income U.S. children who participate in multiple public health programs. This system is intended to characterize trends and patterns in key indicators of nutritional status so that the information can be used for program planning and targeting. The indicators monitored by PedNSS are birth weight, childhood growth status, anemia, and breast-feeding patterns. From 1980 through 1991, the trends for low birth weight, low height-for-age (shortness), low weight-for-height (thinness), and high weight-for-height (overweight) were stable for all children monitored by the PedNSS, with the exception of Asian children, who were predominantly of Southeast Asian refugee background. In the early 1980s, the prevalence of low birth weight and shortness was higher among Asian children than among children of other racial or ethnic groups who were monitored by the PedNSS. However, these prevalences declined steadily from 1980 through 1991. By 1991, the prevalences of low birth weight and shortness for Asian children were similar to those observed for children of other races/ethnic groups. Overall, low-income U.S. children had a slightly lower height-for-age than expected, indicating that some of these children were at a health and nutritional disadvantage. The prevalence of overweight varied among different racial/ethnic groups; Hispanic and Native American children had the highest prevalences of overweight. The 20%-30% prevalence of anemia among low-income children monitored by the PedNSS was higher than among the general population, reflecting in part the preferential enrollment and retention of anemic children by public health nutrition programs and also indicating that many children had inadequate iron nutrition. From 1980 through 1991, the prevalence of anemia declined > 5% for most of the age- and race/ethnicity-specific groups monitored by PedNSS. That decline represents an improvement in iron nutritional status. PedNSS is a useful system for the monitoring and characterization of the nutrition status of low-income children at both state and national levels.  相似文献   
8.
OBJECTIVES. The purpose of the study was to identify cases of hypervitaminosis D caused by the inadvertent overfortification of milk from a home-delivery dairy and to identify risk factors for this illness. METHODS. Hospital discharge, laboratory, and state health department data were used to define, identify, and describe cases of hypervitaminosis D diagnosed in the exposed communities between January 1, 1985, and June 30, 1991. To identify disease risk factors, community-based sex- and age-matched controls were used in a case-control study. RESULTS. Of the 56 case patients identified, at least 41 were hospitalized; 2 died. The study included 33 case patients and 93 control subjects. Nineteen of the 33 case patients had been customers of the implicated dairy. Risk of illness rose with increasing consumption of the dairy's milk and was also associated with vitamin D supplement use, sunburn susceptibility, and cancer history. Accounting for these factors did not alter the association between drinking the dairy's milk and developing hypervitaminosis D. CONCLUSIONS. Overfortification of milk with vitamin D can lead to hypervitaminosis D, manifested by severe illness and death. The episode highlights the need for monitoring the fortification process and enforcing the upper limit for vitamin D addition to milk.  相似文献   
9.
10.
OBJECTIVE: Throughout health care literature, vulnerability is widely accepted as a potential issue for all patients yet the consensus on the meaning of and practical strategies to reduce or manage these 'harmful agents' in the clinical context are rarely offered. Three main themes emerge from the related literature which can be further refined into general terms of; social vulnerability--a person's basic statistical data in relation to their potential for illness; psychological vulnerability--the actual or potential harm to the identity of self and/or other emotional effects such as anxiety or stress caused by the ailment or treatment; and physical vulnerability--which refers to the actual physiological state where an individual is susceptible to further morbidity or mortality. SETTING: Acute care facilities. PRIMARY ARGUMENT: Although there is acknowledgment within the literature that individuals will experience some form of vulnerability when hospitalised, the complexity of what defines vulnerability for individuals causes further problems for patients and health professionals alike. CONCLUSIONS: This paper attempts to define vulnerability within the context of Western health care systems and raises the following issues: all states of vulnerability are accurate and appropriate in the context of the study or incidence alluded to, but further discussion and research is required to achieve a consensus to when, how, why and who is vulnerable. It is this recognition of the potentially differing classifications of vulnerability and the particular contexts that can be used that may assist nurses and other health care professionals with, not only problems associated with a patient's hospitalisation, but in the implementation of appropriate strategies to individual patient's cases.  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