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   24881篇
  免费   1807篇
  国内免费   69篇
耳鼻咽喉   237篇
儿科学   975篇
妇产科学   826篇
基础医学   3233篇
口腔科学   336篇
临床医学   3164篇
内科学   4437篇
皮肤病学   540篇
神经病学   2380篇
特种医学   544篇
外科学   2637篇
综合类   251篇
一般理论   36篇
预防医学   3386篇
眼科学   311篇
药学   1579篇
中国医学   22篇
肿瘤学   1863篇
  2024年   34篇
  2023年   289篇
  2022年   367篇
  2021年   807篇
  2020年   510篇
  2019年   844篇
  2018年   858篇
  2017年   646篇
  2016年   669篇
  2015年   717篇
  2014年   980篇
  2013年   1418篇
  2012年   2127篇
  2011年   2278篇
  2010年   1180篇
  2009年   1059篇
  2008年   1688篇
  2007年   1797篇
  2006年   1589篇
  2005年   1404篇
  2004年   1244篇
  2003年   1107篇
  2002年   1011篇
  2001年   197篇
  2000年   142篇
  1999年   146篇
  1998年   176篇
  1997年   105篇
  1996年   86篇
  1995年   91篇
  1994年   67篇
  1993年   48篇
  1992年   76篇
  1991年   61篇
  1990年   68篇
  1989年   51篇
  1988年   67篇
  1987年   66篇
  1986年   55篇
  1985年   61篇
  1984年   41篇
  1983年   35篇
  1982年   31篇
  1981年   27篇
  1979年   40篇
  1975年   31篇
  1974年   38篇
  1973年   42篇
  1972年   29篇
  1971年   26篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
OBJECTIVE: The purpose of this study was to evaluate a pilot occupational therapy wellness program designed to teach elders the importance of participation in meaningful social and community occupations to their quality of life. METHOD: Sixty-five older adults participated in this pilot wellness program held at each of three senior apartment complexes. Measures of health-related quality of life using the SF-36 Health Survey and frequencies of social and community participation from a program-specific intake form were completed by 39 participants before and after the 6-month program. Participants also evaluated components of the program through a satisfaction survey. RESULTS: Scores on the SF-36 Health Survey were significantly higher in vitality, social functioning, and the mental health summary scores following participation in the program. Participants reported an increased frequency of socialization and community participation with an average of 55% participating in at least three or more activities per week before the program to an average of 66% participating after the program. Participants who benefited the most attended more classes, were older, and were nondrivers. Eighty percent of those polled rated the pilot program as good or excellent. CONCLUSION: This pilot study provides additional support for prevention efforts for elders in the community. Wellness programs for seniors may be most effective if targeted to those who are older and nondrivers.  相似文献   
22.
23.
Abstract: We have analyzed the plasma pharmacokinetics of busulfan in 272 patients receiving high-dose oral busulfan and intravenous cyclophosphamide in conjunction with allogeneic or autologous bone marrow transplantation. The patients ranged in age from 2 months to 59 yr (mean 10, median 12 yr) and had the following diagnoses: thalassemia or sickle cell anemia (n = 74); leukemia or myelodysplasia (n = 112); inborn errors of metabolism (n = 41) or immunodeficiency (n = 45). Plasma specimens were collected following the first dose for each patient which ranged from 1 to 4 mg/kg (mean ± SD, 1.21 ± 0.41, median 1.15). Busulfan was quantitated using ultraviolet absorbance detection after derivatization and HPLC separation. Pharmacokinetic parameters were derived by modeling the raw data to fit first-order single compartment kinetics. The kinetic parameters showed wide interpatient variability independent of age and diagnosis. There was a statistically significant correlation of age with the following parameters: area under the curve (AUC); maximal concentration; minimum concentration; clearance; volume of distribution and absorption half-time. The coefficients of determination (i.e. correlation coefficient squared) were low ranging from 0.04 to 0.12 implying only a small part (i.e. 4–12%) of the variance was explained by age. Although busulfan pharmacokinetics are age-related most of the variability is not explained by age or diagnosis.  相似文献   
24.
Finzi Eric  MD  PhD    Spangler Amy  MPAS  PA-C 《Dermatologic surgery》2005,31(8):916-922
Background. Redundant facial and neck skin is a major feature of aging and historically has been corrected surgically. Recently, monopolar radiofrequency application has been introduced for nonablative tissue tightening of skin by volumetric heating of the deep dermis. It has been able to improve neck and cheek laxity and periorbital rhytides and to elevate eyebrows. However, questions remain as to the ideal parameters needed to optimize the use of radiofrequency.
Objective. To determine the safety and report on the efficacy of a radiofrequency application that involves a multipass vector (mpave) technique to target facial and neck skin laxity.
Methods. Twenty-five patients (skin types I to V) with mild to severe facial and neck laxity received one treatment session with monopolar radiofrequency. Treatment parameters, adverse events, and digital photographs were recorded. All patients were treated with a multipass vector technique consisting of four to five passes targeted over areas of skin that would most improve facial laxity. The multipass vector (mpave) treatment approach is described. Energy levels ranged from 62 to 91 J/cm2 per pulse.
Results. All patients experienced some immediate erythema and edema, which had completely resolved in most patients within 48 hours. No scarring or dyspigmentation was noted on follow-up at 6 and 12 weeks. Photographic analysis of pre- and post-treatment digital images revealed cosmetic improvement in facial and neck laxity in 96% of patients. The majority of patients demonstrated a moderate or better improvement. Stacked pulses in the submental region were shown to reduce fat.
Conclusions. The direct application of monopolar radiofrequency to facial and neck skin using a multipass vector (mpave) treatment approach was safely tolerated in patients of all skin types. Patient satisfaction correlated well with photographic analysis, and the technique was shown to be efficacious for most patients.  相似文献   
25.
When rural/urban differences are found in health status or health care use, it is often desirable to identify those factors (such as age, social structure, income, etc.) that influence such differences. To this end, researchers often test rural/urban differences in age, social structure, income, etc., for statistical significance. Also, researchers commonly perform multivariate analyses (such as multiple regressions) to examine rural-urban differences in the influence of various independent variables on the dependent variable of interest. Frequently, researchers discover: (1) statistically significant rural/urban differences in the independent variables (such as age, social structure, income, etc.) and (2) statistically significant rural/urban differences in the effects of these independent variables (i.e., statistically significant rural/urban differences in regression coefficients). The analysis typically stops here, without addressing the relative contributions of (1) and (2) to the rural/urban differences in the dependent variable. This paper argues that the relative contributions of (1) and (2) have important implications for the way policy-makers address rural health problems. This paper presents a method for assessing the relative contributions of differences in the independent variables and differences in regression coefficients to observed differences in the dependent variable, and illustrates the application of the method by analyzing rural/urban differences in the risk of institutionalization.  相似文献   
26.
27.
This study examined ethical concerns related to exposing participants with childhood victimization histories to both trauma-specific and non-trauma-specific stimuli. We asked participants questions about childhood victimization experiences and exposed participants to a negatively-arousing experimental condition. Following each of these procedures and at a one-week follow-up session, participants completed a measure designed to asses their reactions to participation. The measure included several questions to assess reactions including questions about distress, benefit, and willingness to participate in the study again. Overall, participants reported low levels of distress and described their participation experience as interesting, enjoyable, and somewhat beneficial. Participants also indicated that they would be willing to participate in the study again with the knowledge of what participation was actually like. Participants with childhood trauma histories and PTSD symptoms reported more distress during the childhood maltreatment screening compared to other participants. However, the level of distress they experienced was mild and transitory. Our findings add to the emerging data indicating that individuals find their participation in trauma-related research to be a positive experience overall, rather than a harmful one.  相似文献   
28.
PURPOSE: The purpose of this study was to examine the predictive validity of a collection of prelinguistic skills measured longitudinally in the 2nd year of life to language outcome in the 3rd year in children with typical language development. METHOD: A collection of prelinguistic skills was assessed in 160 children early (M = 14.31 months; SD = 1.36) and late (M = 19.76 months; SD = 1.16) in their 2nd year by using the Communication and Symbolic Behavior Scales Developmental Profile Behavior Sample (A. Wetherby & B. Prizant, 2002). The relation between the prelinguistic skills and the receptive and expressive language near the 3rd birthday was examined. RESULTS: Significant correlations were observed between many prelinguistic skills and language outcome. Regression analyses indicated that comprehension both early and late contributed unique variance to receptive and expressive language outcome. In addition, early in the 2nd year, inventory of conventional gestures contributed uniquely to receptive language outcome, and acts for joint attention contributed uniquely to expressive outcome. Late in the 2nd year, inventory of consonants contributed uniquely to expressive outcome. CONCLUSIONS: The findings demonstrate continuity between prelinguistic and linguistic skills and how individual differences in a number of prelinguistic skills contribute collectively and uniquely to language outcome in typically developing children.  相似文献   
29.
A community sample of 1106 adults was examined to assess the impact of the doctor-patient relationship on participants' avoidance of treatment for a recognized medical or psychological problem. Of five aspects of participants' previous experience with their physicians, all but waiting time predicted participants' self-reported treatment avoidance. In two logistic regression models participants who felt their physicians listened more to their concerns were less likely to avoid treatment for both medical and psychological problems during the previous 12 months. These findings suggest that patients' perceptions of how they are treated by physicians may help explain why many people delay or avoid healthcare treatment, even when faced with a significant health problem.  相似文献   
30.
The NTP has a long history of using Fischer rats and has compiled a large database of incidences of lesions seen in control animals. Such a database is lacking for Harlan Sprague-Dawley (SD) rats. The intention of this paper is to report spontaneous lesions observed in female vehicle control Harlan SD rats, and to compare the incidence in 2 strains of rats (Fischer and Harlan SD) used in NTP studies. Female Harlan SD rats served as the test animals for a special series of 2-year studies. Male rats were not used in these studies. Complete histopathology was performed on all animals, and the pathology results underwent comprehensive NTP pathology peer review. The most commonly observed neoplasms in these female control Harlan SD rats were mammary gland fibroadenoma (71%), tumors of the pars distalis of the pituitary (41%) and thyroid gland C-cell tumors (30%). Female Fischer rats had incidences of 44% for mammary gland fibroadenomas, 34% for tumors of the pars distalis, and 16% for thyroid gland C-cell tumors. Fischer rats had a 15% incidence of clitoral gland tumors, while the Harlan SD rats had an incidence of < 1%. In contrast to Fischer F344 rats, the Harlan SD rats had a high incidence of squamous metaplasia of the uterus (44.2%). Squamous metaplasia is not a lesion commonly observed in NTP control Fischer rats. The Harlan SD rats had a very low incidence of mononuclear cell leukemia (0.5%), compared with an incidence of 24% in female Fischer rats.  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