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   3402篇
  免费   231篇
  国内免费   79篇
耳鼻咽喉   22篇
儿科学   223篇
妇产科学   41篇
基础医学   414篇
口腔科学   129篇
临床医学   385篇
内科学   694篇
皮肤病学   82篇
神经病学   204篇
特种医学   469篇
外科学   211篇
综合类   73篇
一般理论   1篇
预防医学   311篇
眼科学   25篇
药学   215篇
  2篇
肿瘤学   211篇
  2021年   26篇
  2020年   23篇
  2019年   30篇
  2018年   43篇
  2017年   39篇
  2016年   39篇
  2015年   55篇
  2014年   73篇
  2013年   102篇
  2012年   123篇
  2011年   137篇
  2010年   138篇
  2009年   112篇
  2008年   109篇
  2007年   133篇
  2006年   112篇
  2005年   102篇
  2004年   80篇
  2003年   60篇
  2002年   62篇
  2001年   91篇
  2000年   72篇
  1999年   69篇
  1998年   142篇
  1997年   170篇
  1996年   144篇
  1995年   120篇
  1994年   126篇
  1993年   108篇
  1992年   74篇
  1991年   71篇
  1990年   71篇
  1989年   89篇
  1988年   88篇
  1987年   74篇
  1986年   82篇
  1985年   83篇
  1984年   47篇
  1983年   33篇
  1982年   34篇
  1981年   45篇
  1980年   34篇
  1979年   25篇
  1978年   12篇
  1977年   26篇
  1976年   39篇
  1975年   22篇
  1974年   18篇
  1973年   12篇
  1972年   15篇
排序方式: 共有3712条查询结果,搜索用时 15 毫秒
81.
82.
83.
The aim of this study was to assess the clinical safety of performing microlaryngeal surgery (MLS) under general anaesthesia in selected patients in the ambulatory setting. Twenty-two adult patients were scheduled to have tissue specimens of the larynx taken by biopsy (54%), for vocal cord polypectomy (41%) or for vocal cord cyst excision (5%). Twenty-one ASA I and II patients (95%) were discharged home the same day of the procedure. Two of them presented with laryngospasm after extubation of the trachea. One ASA III patient (5%) had to be admitted overnight because of severe laryngospasm and bronchospasm, but was discharged the day after the operation. None of the patients had significant complications after leaving the recovery room (mean stay 85 min). There were no re-admissions to the hospital. Our data suggests that microlaryngeal surgery in selected patients can be safely performed on a day case basis.  相似文献   
84.
A laboratory model for studying blast overpressure injury   总被引:3,自引:0,他引:3  
Blast injury remains an important source of trauma in both civilian and military settings. We have studied a recently developed blast wave generator to evaluate its effectiveness for laboratory study of blast injury. In order to determine the reliability of the device and the pathology of the lesions caused by the short duration (0.5-1.0 msec), and high intensity (60-375 psi) pressure wave, laboratory rats were exposed to the pressure waves generated by the machine. The animals were divided into three groups: the first exposed to midthoracic blasts, the second to abdominal blasts, and a group of controls exposed to a gentle stream of gas. Group I showed gross and microscopic evidence of lung blast injury of "rib imprint" hemorrhages, intra-alveolar hemorrhage, marked increase in lung weight, prolonged apnea, and bradycardia. Group II showed typical blunt abdominal trauma at the closest ranges, but characteristic submucosal hemorrhages up to 4.0 cm from the blast nozzle. In both groups, a protective effect was seen in heavier animals. The blast wave generator permits reproducible blast injury in the laboratory that is safer and faster than current methods. The lung and bowel lesions induced are grossly and microscopically similar to injuries of blast exposure seen in clinical patients.  相似文献   
85.
86.
Pharmaceutical representatives in academic medical centers   总被引:4,自引:3,他引:4  
OBJECTIVE: To determine the nature, frequency and effects of internal medicine housestaff and faculty contacts with pharmaceutical representatives (PRs). DESIGN AND SETTING: The authors surveyed internal medicine faculty at seven midwest teaching hospitals and housestaff from two of the teaching programs. The survey asked about type and frequency of contacts with PRs and behavior that might be related to these contacts. T-tests and logistic regression were used to estimate the relationship between reported physician contacts and behavioral changes. PARTICIPANTS: Two hundred forty faculty (78%) and 131 house officers (75%) responded to the survey. RESULTS: Faculty and housestaff averaged 1.5 brief contacts per month with PRs. Housestaff averaged more than one meal/month at pharmaceutical company expense. Twenty-five percent of faculty and 32% of residents reported changing their practices at least once based on PR contact. Independent predictors of faculty change in practice were brief or extended conversations and free meals. Predictors of faculty requests for formulary addition were brief conversations and receipt of honoraria or research support. Only brief conversations independently predicted housestaff changes in practice. CONCLUSION: Academic housestaff and faculty have frequent PR contact; such contact is related to changes in behavior. The potential for influence of PRs in academic medical centers should be recognized, and their activities should be evaluated accordingly.  相似文献   
87.
BackgroundThe test battery classically used for return-to-sport (RTS) decision-making after anterior cruciate ligament (ACL) reconstruction (ACLR) may not be sufficient, as it does not include a qualitative analysis of movement. Therefore, the Landing Error Scoring System (LESS) scale was adapted to a primary functional test in the typical RTS test battery: the single leg hop for distance (SHD).Hypothesis/ PurposeThe aim of this study was to determine the intra-rater reliability of the LESS scale adapted to the SHD (SHD-LESS scale) in healthy young athletes.Study DesignReliability analysisMethodsNineteen healthy individuals (14 men, 5 women; mean age: 22.4 years) participated in the study. Participants performed the SHD tasks on both limbs (dominant and non-dominant) using a standardized protocol in two sessions that were one week apart (single reviewer; 2-dimensional video). Intra-class correlation coefficients (ICC2,1) were used to measure the reproducibility of the scale in the dominant (dom) and non-dominant (nondom) limbs. Additionally, limb data (dom and nondom) were pooled and evaluated collectively with intra-class correlation coefficients. The Kappa coefficient was used to assess the reproducibility of each individual item of SHD-LESS scale.ResultsThe intra-rater reliability was good (ICCdom = 0.77; ICCnondom = 0.87; ICCpooled = 0.87) for the overall SHD-LESS scale scores. Agreement of SHD-LESS individual items ranged from 62% to 100%. Dorsiflexion at initial contact (97% agreement; kappa value=0.79) and knee valgus after landing (88% agreement; kappa value=0.65) had excellent agreement and kappa values.ConclusionThe newly-adapted SHD-LESS scale showed good intra-rater reliability overall. Further studies should evaluate the impact of using the SHD-LESS scale within the RTS test battery on outcomes in patients after ACLR.Level of Evidence3  相似文献   
88.
89.
T cells recognize antigen (Ag) in the form of peptides bound to the major histocompatibility complex (MHC) molecule. One of the important issues in evolutionary immunology is to identify the stage in phylogeny when this mode of Ag recognition emerged. At present, there is a considerable controversy as to whether the cartilaginous fish have the bona fide MHC. In our previous study, we showed that the nurse shark, a member of the cartilaginous fish, has (a) gene(s) capable of encoding MHC class II a chains. In the present study, we examined the polymorphism of nurse shark MHC class II a chain genes designated Gici-DAA and Gici-DBA using the polymerase chain reaction. The Gici-DAA and Gici-DBA genes had six and five alleles, respectively, and individual alleles usually differed by multiple nucleotides. In addition, most of the nucleotide substitutions were located at the putative Ag-binding sites, where non-synonymous substitutions occurred more frequently than synonymous substitutions. The fact that the Gici-DAA and Gici-DBA genes display a polymorphism pattern essentially similar to that of mammalian MHC genes playing a major role in Ag presentation suggests that the cartilaginous fish have the bona fide MHC. Thus, the MHC-peptide-based T cell recognition system appears to have arisen at or before the emergence of the cartilaginous fish.  相似文献   
90.
Laboratory monitoring of HIV-infected children is the current standard of care in the United States to guide the appropriate use of antiretroviral therapy (ART). Although ART is becoming a reality in some developing countries, laboratory monitoring of ART is costly, necessitating creative approaches to monitoring. As an initial step to guide monitoring of HIV progression in low resource settings, we assessed the utility of the physical examination to predict clinical progression of HIV. We conducted a retrospective cohort study of HIV-infected children using data from Pediatric AIDS Clinical Trials Group Protocol 300. We developed a clinical predictive model, and compared the utility of the clinical model to the change in HIV RNA viral load as diagnostic tests of ART failure. The clinical model incorporated treatment regimen, age, and height velocity: a three-level clinical predictive model provided likelihood ratios of 0.3, 3.9, and 14. For decline in RNA the likelihood ratios were 0.2 (> 1 log decline), 1.4, and 3.5 (> log increase). We developed a simple clinical predictive model that was able to predict clinical progression of HIV after initiation of new ART. The clinical model performed similarly to using changes in HIV RNA viral load. These data should be validated internationally and prospectively, because the test subjects were from a resource rich environment and growth patterns in undernourished children may be impacted differently by HIV and its treatment. The model was most pertinent to children 36 months of age or younger, and was conducted in children receiving monotherapy and dual therapy.  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