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   838篇
  免费   44篇
  国内免费   16篇
耳鼻咽喉   2篇
儿科学   33篇
妇产科学   3篇
基础医学   95篇
口腔科学   38篇
临床医学   90篇
内科学   134篇
皮肤病学   4篇
神经病学   71篇
特种医学   106篇
外科学   124篇
综合类   46篇
预防医学   85篇
眼科学   6篇
药学   43篇
中国医学   1篇
肿瘤学   17篇
  2022年   4篇
  2021年   6篇
  2020年   4篇
  2019年   13篇
  2018年   11篇
  2017年   6篇
  2016年   8篇
  2015年   15篇
  2014年   17篇
  2013年   25篇
  2012年   32篇
  2011年   25篇
  2010年   36篇
  2009年   24篇
  2008年   29篇
  2007年   33篇
  2006年   23篇
  2005年   27篇
  2004年   22篇
  2003年   34篇
  2002年   23篇
  2001年   22篇
  2000年   18篇
  1999年   26篇
  1998年   30篇
  1997年   31篇
  1996年   29篇
  1995年   20篇
  1994年   19篇
  1993年   15篇
  1992年   6篇
  1991年   17篇
  1990年   14篇
  1989年   28篇
  1988年   24篇
  1987年   25篇
  1986年   11篇
  1985年   13篇
  1984年   14篇
  1983年   16篇
  1982年   8篇
  1981年   9篇
  1980年   14篇
  1979年   10篇
  1978年   8篇
  1977年   10篇
  1976年   8篇
  1971年   4篇
  1970年   4篇
  1968年   3篇
排序方式: 共有898条查询结果,搜索用时 187 毫秒
1.
2.
Sonoelasticity imaging of prostate cancer: in vitro results   总被引:2,自引:0,他引:2  
  相似文献   
3.
Does unaided awareness of a hospital affect former patients' preferences for and intention to use the medical services of that hospital? Do customer preferences toward hospitals influence their intentions to use the medical services of those hospitals? To what extent does satisfaction with previous hospital stays affect former patients' intentions to return to the same hospital? The authors provide some tentative answers to these questions. The results of an exploratory field study of former inpatients of one hospital are reported. Several recommendations for research and hospital marketing strategies are provided.  相似文献   
4.
OBJECTIVE: To describe the rationale, methodology, and general sample characteristics of the Canadian Psychiatric Association (CPA) practice profile survey, a national survey of psychiatrists and psychiatric practice. METHOD: Mail-in interviews were sent to all Canadian psychiatrists listed in their provincial registers and to all active CPA members (total = 3628). Respondents provided general information about their professional activities for one 24-hour day and detailed information for 1 randomly selected hour. Patient information--including sociodemographics, diagnostic profiles, functioning levels, risk of harm to self or others, and disposition--was elicited for 1 patient seen during the random hour as well as for the most seriously ill patient receiving clinical services that day. RESULTS: There was a 45.5% response rate. Questionnaires completed by nonpsychiatrists or with a large percentage of missing or incorrect data were eliminated (107 surveys), resulting in a final sample size of 1570. CPA members and those from Western Canada responded at a higher rate to the survey. The results suggest some cause for concern about future manpower shortages. Most psychiatrists practise eclectically, seeing patients across the life-span, and working in both community and institutional settings. The old and the young appear to be underserviced, compared with adults. CONCLUSIONS: This study represents an important step forward in evaluating the profile and activities of the profession.  相似文献   
5.
Screening for early ovarian cancer   总被引:5,自引:0,他引:5  
Taylor  KJ; Schwartz  PE 《Radiology》1994,192(1):1
  相似文献   
6.
The CT and MR features of cortical calcification and meningeal angiomatosis are typical of Sturge-Weber-Dimitri disease but are unusual in children less than 1 year of age. This case describes a child presenting with both of these features bilaterally in the neonatal period and represents an unusual presentation of this disorder.  相似文献   
7.
8.
The objective of this study was to evaluate the dentoskeletal changes consequent to orthodontic treatment in subjects with Class II subdivision malocclusions, treated with asymmetric extractions, compared with a normal-occlusion control group. The sample consisted of 3 groups, with 30 subjects in each: normal-occlusion subjects (group 1), untreated Class II subdivision subjects (group 2), and Class II subdivision patients treated with asymmetric extractions (group 3). All subjects had a full complement of permanent teeth at the beginning of treatment. The average ages of the subjects were 22.42, 15.76, and 18.57 years, respectively, in groups 1, 2, and 3. Measurements of relative differences in the spatial position of dental and skeletal bilateral landmarks were obtained from the submentovertex and posteroanterior cephalometric (PA) radiographs. The t test for independent samples was used to compare group 1 with groups 2 and 3 at different times. Results from the submentovertex radiograph showed that asymmetric extractions in Class II subdivision malocclusions will maintain the differences in the anteroposterior positions of right and left, maxillary and mandibular first molars, as would be expected with the treatment protocols used. There were no significant skeletal changes that could be attributed to the treatment approaches investigated or transverse collateral effects with the asymmetric mechanics used. It was also demonstrated that treatment of Class II subdivision malocclusions with asymmetric extractions produced corrections of maxillary and mandibular dental midline deviations with the midsagittal plane, without canting the occlusal plane or any other investigated horizontal plane, as seen in the PA radiograph. Treatment of Class II subdivision malocclusions with asymmetric extractions constitutes a beneficial approach to this problem.  相似文献   
9.
Tumor vascular signals in renal masses: detection with Doppler US   总被引:3,自引:0,他引:3  
Ramos  IM; Taylor  KJ; Kier  R; Burns  PN; Snower  DP; Carter  D 《Radiology》1988,168(3):633-637
The vascularity of 49 renal masses (26 malignant and 23 benign lesions) was investigated with duplex Doppler ultrasound. Doppler signals obtained at the margins of renal masses were defined as "tumor signals" when the Doppler-shifted frequency of the lesion exceeded the frequency shift in the ipsilateral main renal artery. These exceeded 2.5 kHz with a 3-MHz insonating frequency. Among the 26 renal masses that subsequently proved to be malignant, tumor signals were obtained in 15 of 18 (83%) untreated renal cell carcinomas, in three of four Wilms tumors, and in two patients with metastases to the kidney, but not in the one patient with lymphoma. None of the 23 benign renal masses demonstrated tumor signals. Tumor vascularity in malignant lesions gives rise to abnormal, high-velocity, Doppler-shifted signals that can help in the differential diagnosis of renal masses.  相似文献   
10.
We examined the factors influencing maternal food intake and pup growth in Norway rats. Mother rats allowed pups in naturally large litters to grow at a slower rate than pups in naturally small litters. Pups reared by dams in a warm ambience (26°C) gained weight more slowly than dams at 22°C, and maternal food intake but not weight gain was depressed in the high ambient temperature. Pup growth at 18°C was unimpaired, with those dams eating no more and gaining no less weight than dams at 22°C. Nest material, however, was found to be essential for the successful rearing of young at cooler ambient temperatures. While restriction of food during gestation resulted in a marginally lower weight gain for the pups during the first 2 weeks postpartum, the dams appeared not to mobilize corporal stores or increase their food intake during lactation. Heavy body weight mothers did not eat any more, nor did they gain any less weight nor rear larger pups than light body weight dams. Rat mothers increased their consumption of a diet diluted with non-nutritive fiber to equal the nutritive intake of their controls, with their pups not differing in their growth rate. Pups reared by dams eating a high quality diet grew faster than pups with dams on the control diet. Food intake by mother rats is required during lactation relative to the amount of milk that is delivered to the pups, rather than to an absolute amount of food. Lactating females with a concurrent pregnancy neither increase their food intake nor appear to mobilize their corporal stores to deal with the added energetic drain of pregnancy. Indeed, their young grew somewhat more quickly than pups nursed by dams that were simply lactating. Taken as a whole, these results suggest that Norway rat dams apparently do not monitor and defend a maximal pup growth rate. Rather, rat dams seem to continue to defend their own homeostasis, and by doing so, allow the young to grow and survive under a wide variety of circumstances.  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