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   3172篇
  免费   284篇
  国内免费   10篇
耳鼻咽喉   39篇
儿科学   84篇
妇产科学   40篇
基础医学   361篇
口腔科学   89篇
临床医学   365篇
内科学   644篇
皮肤病学   17篇
神经病学   366篇
特种医学   116篇
外科学   358篇
综合类   103篇
一般理论   3篇
预防医学   405篇
眼科学   39篇
药学   224篇
肿瘤学   213篇
  2023年   28篇
  2022年   29篇
  2021年   68篇
  2020年   39篇
  2019年   71篇
  2018年   88篇
  2017年   64篇
  2016年   51篇
  2015年   43篇
  2014年   94篇
  2013年   176篇
  2012年   194篇
  2011年   186篇
  2010年   110篇
  2009年   113篇
  2008年   197篇
  2007年   196篇
  2006年   166篇
  2005年   161篇
  2004年   150篇
  2003年   172篇
  2002年   112篇
  2001年   85篇
  2000年   61篇
  1999年   76篇
  1998年   26篇
  1997年   31篇
  1996年   22篇
  1995年   18篇
  1994年   23篇
  1993年   14篇
  1992年   57篇
  1991年   33篇
  1990年   48篇
  1989年   36篇
  1988年   52篇
  1987年   36篇
  1986年   39篇
  1985年   54篇
  1984年   30篇
  1983年   24篇
  1982年   15篇
  1981年   14篇
  1979年   19篇
  1978年   17篇
  1976年   8篇
  1975年   12篇
  1974年   13篇
  1973年   11篇
  1969年   9篇
排序方式: 共有3466条查询结果,搜索用时 15 毫秒
11.
Women's life situation and experiences during pregnancy were prospectively studied in relationship to the development of congenital malformations (CMs) in their offspring, within samples of 84 offspring of pregnant index women with a history of nonorganic psychosis and 100 offspring of pregnant control women. Within both samples, offspring CMs were related to more problematic maternal life situations during pregnancy, the common denominator in these problems across samples being difficulties associated with the husband. Little relationship was found between CMs and the woman's own attitude toward the pregnancy or her mental condition during pregnancy. In both groups, total life situational problems and distress were more strongly related to the development of very minor CMs (termed "variants") than to the major, classical CMs.  相似文献   
12.
Burnout is a syndrome of emotional exhaustion, depersonalization, and reduced personal accomplishment that can occur among individuals who do "people work" of some kind. Health care providers, including dentists, are at high risk for burnout because their occupation often requires intense interaction with fearful, demanding patients on a daily basis. The purpose of this study was to assess the prevalence of burnout among Texas dentists using a standardized measurement device, the Maslach Burnout Inventory (MBI). Dentists attending the 1989 Texas Dental Association Annual Session were surveyed using the MBI. The respondents' results were analyzed and compared to each other as well as to the norms of medicine and to society (human service workers nationwide). Among the Texas sample, male dentists scored significantly higher for emotional exhaustion and depersonalization than did female dentists. When compared to the norms of medical workers, Texas dentists scored higher burnout in the depersonalization subscale, but lower burnout for personal accomplishment. The Texas sample again scored lower for burnout in the personal accomplishment subscale when compared to societal norms. At no time did the Texas sample fall into the high range of experienced burnout as defined by the survey instrument. Texas dentists did not appear "burned out" as a group and actually demonstrated an increased sense of personal accomplishment in their profession.  相似文献   
13.
An outbreak of nosocomial fungemia due to the unusual yeast, Pichia anomala occurred in the pediatric wards of our hospital over a period of 23 months (April 1996 to February 1998). A total of 379 neonates and children (4.2% admissions) were infected. The probable index case was admitted to the pediatric emergency ward, with subsequent transmission to the premature nursery, pediatric intensive care units, and other children wards. Carriage on the hands of health care personnel was likely to be responsible for dissemination of the fungus. The outbreak could only be controlled after a health education campaign to improve hand-washing practices was instituted and after nystatin-fluconazole prophylaxis to all premature neonates and high-risk infants was introduced. In a case-control study, we identified a lower gestational age, a very low birth weight (<1,500 g), and a longer duration of hospital stay as significant risk factors associated with P. anomala fungemia in premature neonates. We conducted a culture prevalence survey of 50 consecutive premature neonates and found that 28% were colonized with P. anomala at a skin or mucosal site on the date of delivery and that 20% of these neonates subsequently developed P. anomala fungemia. We performed multilocus enzyme electrophoresis on 40 P. anomala outbreak isolates (including patient and health care workers' hand isolates), and the results suggested that these isolates were identical. Our study highlights the importance of P. anomala as an emerging nosocomial fungal pathogen.  相似文献   
14.
OBJECTIVE: To examine psychosocial predictors of distress (mood disturbance, perceived stress, caregiver burden) in parents of children undergoing stem cell or bone marrow transplantation (BMT). METHOD: Measures of prior illness experiences, premorbid child behavior problems, family environment, social support, and parental coping behavior were obtained from the resident parents of 151 children prior to the children's admission for BMT. Parents subsequently completed assessments of their mood disturbance, perceived stress, and caregiving burden on a weekly basis through week +6 post-BMT, and then monthly through month +6 post-BMT. RESULTS: Significant changes were observed in parental distress across the course of BMT. After correcting for demographic and medical factors, several significant predictors of parental distress trajectories were identified, including prior parent and patient illness-related distress, premorbid child internalizing behavior problems, the family relationship dimensions of the family environment, and parental avoidant coping behaviors. Multivariable models were developed using a hierarchical modeling approach. The best-fit model accounted for approximately 50% of the variance in parental global distress. CONCLUSIONS: Subgroups of parents at higher risk for increased distress during the acute phase of transplant have been identified. These findings can help target parents who may be in greater need of intervention aimed at reducing transplant-related distress.  相似文献   
15.
During an outbreak of pseudobacteremia in a children's hospital, Ewingella americana was found in blood cultures from 20 patients. E. americana was inoculated into blood culture bottles at the time of specimen collection due to cross contamination from nonsterile, citrated blood collection tubes used for coagulation studies. Antimicrobial susceptibility testing and plasmid profiling were used to assess the association between patient isolates and isolates from unused blood collection tubes. All E. americana isolates had similar antibiograms (i.e., resistance only to cephalothin) when tested at 37 degrees C. However, when the same isolates were tested for antimicrobial susceptibility at 25 degrees C, a different antibiogram (i.e., resistance to chloramphenicol, ampicillin, and cephalothin) was found. The majority of these isolates also demonstrated a unique four-plasmid profile (130, 56, 4.6, and 3.1 megadaltons), and two of these plasmids (130 and 56 megadaltons) were characterized as temperature-sensitive plasmids. An epidemiologic link between outbreak-associated isolates obtained from different time periods in the outbreak was supported by evidence of a significant trend in the ability of the outbreak-associated isolates to reduce nitrate, together with the presence of the resistance antibiogram at 25 degrees C and the demonstration of the unique four-plasmid profile.  相似文献   
16.
Pseudomonas pickettii caused respiratory tract colonization in five infants in the special care nursery of a Chicago hospital. All organisms had the same antimicrobial susceptibilities. Endotracheal suctioning with saline from 5-ml unit-dose vials was identified by epidemiologic investigation as a risk factor for colonization. The vials of saline were contaminated with a strain of P. pickettii having the same antimicrobial susceptibility pattern as the isolates from patients. As part of an investigation of the manufacturing plant where the saline solution was produced, P. pickettii was recovered from deionized water used to make the product and from several sites in the processing line. Bypassing of a 180 degrees F (ca. 82 degrees C) water-holding tank appeared to be temporally related to product contamination. The ability of P. pickettii to survive and grow in this solution has been demonstrated in the laboratory. This outbreak demonstrates that, despite pertinent Food and Drug Administration regulations and company programs for identifying such contamination, intrinsically contaminated solutions can occasionally reach the bedside of the patient.  相似文献   
17.
This is a cohort study of pediatric outpatients receiving total parenteral nutrition (TPN) and follow-up care in a Tennessee hospital between January and June 1999. The study was conducted following an increase in the incidence of candidemia. Of 13 children receiving home TPN, five had candidemia; three were due to Candida parapsilosis. Case patients were more likely to have an underlying hematologic disease (P = 0.02) as well as previous history of fungemia (P = 0.02). Two case patients had successive candidemia episodes 3 months apart; karyotypes and RAPD profiles of each patient's successive C. parapsilosis isolates were similar. Candida spp. were frequently detected in hand cultures from cohort members (four of 10) and family member caregivers (nine of 11); C parapsilosis was isolated from five caregivers. Our findings underscore the challenges of maintaining stringent infection control practices in the home health care setting and suggest the need for more intensive follow-up and coordination of home TPN therapy among pediatric patients.  相似文献   
18.
Patients with the hyper-IgE syndrome have greatly elevated percentages of IgE Fc receptor (Fc epsilon R)-positive B cells, but they have less than 0.1% Fc epsilon R+ T cells (T epsilon cells) and few, if any, Fc epsilon R+ natural killer cells. They also have markedly decreased numbers of IgG receptor positive (Fc gamma R+) T cells (T gamma cells). Patients with the hyper-IgE syndrome resemble in this respect patients with severe atopic dermatitis. Since a portion of T epsilon and T gamma cells of mildly atopic patients react with monoclonal antibody OKT8, they may have a suppressor function. However, whether the low number of T epsilon cells is responsible for the high IgE serum level in hyper-IgE syndrome and atopic dermatitis patients remains to be demonstrated. Attempts to obtain a reliable assay for human IgE synthesis in vitro to investigate the function of Fc epsilon R-positive lymphocytes proved to be difficult. Even isolated B cells from atopic donors seldom produced more than twice the quantity of IgE released from cells incubated in the presence of the protein synthesis inhibitor cycloheximide.  相似文献   
19.
Nocardia brasiliensis, the second most frequently isolated aerobic actinomycete in the clinical laboratory, is usually associated with localized cutaneous infections. However, 22% of 238 N. brasiliensis isolates from the United States and 12% of 66 isolates from Queensland, Australia, which had been collected over a 17-year period, were associated with extracutaneous and/or disseminated diseases. Of the 62 invasive isolates, 37 (60%) were susceptible to ciprofloxacin and/or were susceptible to clarithromycin and resistant to minocycline, compared with only 6 (3%) of 242 localized cutaneous isolates. The 43 isolates with this susceptibility pattern appeared to define a new taxon. They were similar to Nocardia asteroides complex isolates clinically in proportions from persons with pulmonary (70%), central nervous system (23%), and/or disseminated diseases (37%) in the setting of corticosteroids (74%) or AIDS (14%). This putative new taxon differed from N. brasiliensis in the hydrolysis of adenine (92 versus 4%), beta-lactamase patterns on isoelectric focusing, and the presence of two early mycolic acid-ester peaks by high-performance liquid chromatography. Restriction analysis of a 439-bp fragment of the 65-kDa heat shock protein gene revealed that N. brasiliensis and the new taxon had different restriction patterns with 8 of the 11 enzymes tested. Screening of invasive isolates of N. brasiliensis for susceptibility to ciprofloxacin will identify most isolates of the new taxon, which likely represents a new Nocardia species.  相似文献   
20.
BACKGROUND. In 1987, a cooperative study group consisting of five institutions was formed to determine the relative benefits of magnetic resonance imaging (MRI) and endorectal (transrectal) ultrasonography in evaluating patients with clinically localized prostate cancer (stage Ta or Tb). METHODS. Over a period of 15 months, 230 patients were entered into the study and evaluated with identical imaging techniques. We compared imaging results with information obtained at the time of surgery and on pathological analysis. RESULTS. MRI correctly staged 77 percent of cases of advanced disease and 57 percent of cases of localized disease; the corresponding figures for ultrasonography were 66 and 46 percent (P not significant). These figures did not vary significantly between readers; moreover, simultaneous interpretation of MRI and ultrasound scans did not improve accuracy. In terms of detecting and localizing lesions, MRI identified only 60 percent of all malignant tumors measuring more than 5 mm on pathological analysis and ultrasonography identified only 59 percent. CONCLUSIONS. The MRI and ultrasonography equipment that is currently available is not highly accurate in staging early prostate cancer, mainly because neither technique has the ability to identify microscopic spread of disease. Further evaluation with improved equipment may improve the accuracy of these techniques.  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