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   11358篇
  免费   1977篇
  国内免费   66篇
耳鼻咽喉   268篇
儿科学   3161篇
妇产科学   31篇
基础医学   532篇
口腔科学   2043篇
临床医学   1313篇
内科学   1227篇
皮肤病学   212篇
神经病学   395篇
特种医学   202篇
外国民族医学   1篇
外科学   1561篇
综合类   427篇
一般理论   3篇
预防医学   449篇
眼科学   260篇
药学   559篇
  23篇
中国医学   174篇
肿瘤学   560篇
  2024年   70篇
  2023年   592篇
  2022年   363篇
  2021年   620篇
  2020年   904篇
  2019年   912篇
  2018年   808篇
  2017年   768篇
  2016年   671篇
  2015年   589篇
  2014年   816篇
  2013年   996篇
  2012年   609篇
  2011年   515篇
  2010年   482篇
  2009年   460篇
  2008年   421篇
  2007年   428篇
  2006年   320篇
  2005年   299篇
  2004年   178篇
  2003年   174篇
  2002年   133篇
  2001年   133篇
  2000年   101篇
  1999年   78篇
  1998年   85篇
  1997年   84篇
  1996年   69篇
  1995年   63篇
  1994年   50篇
  1993年   64篇
  1992年   59篇
  1991年   59篇
  1990年   45篇
  1989年   50篇
  1988年   53篇
  1987年   34篇
  1986年   23篇
  1985年   47篇
  1984年   43篇
  1983年   24篇
  1982年   22篇
  1981年   10篇
  1980年   25篇
  1979年   11篇
  1978年   11篇
  1977年   8篇
  1974年   7篇
  1973年   6篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
Development and evaluation of a presurgical preparation program   总被引:2,自引:1,他引:1  
Three presurgical preparation programs were developed and evaluated in an Australian hospital utilizing an additive component design. The component basic to all three preparation programs was modeling. This technique was compared with the additional components of teaching child coping skills and parent coping skills via videotape. Subjects were 28 children between the ages of 4 and 13 years who were scheduled for elective surgery. Anxiety of both the children and parents was assessed by self-report and behavior observation. Results indicated that there was no further anxiety reduction by the addition of child and parent coping skills. Results are discussed in terms of the viability of teaching coping skills via videotape particularly to parents. Methodological difficulties associated with research in this area are examined.  相似文献   
42.
We evaluated variables associated with improved late graft survival in 290 children transplanted between 11/1/1984 and 12/31/1997, and who had > 1 year graft survival. We studied the following variables: age, gender, race, primary disease (diseases prone to recurrence, i.e. hemolytic uremic syndrome, focal segmental glomerulosclerosis or oxalosis vs. others), primary vs. retransplant; donor source, acute tubular necrosis, acute rejection episodes in the first year, transplant era and discharge serum creatinine. Graft half-life was defined as the time taken for 1/2 of the grafts functioning at 1 year to fail. There were 205 living donor and 85 cadaveric transplant. The cumulative graft survival at 5 and 10 years was 88% and 75% for living donor, and 72% and 46% for cadaveric, respectively. Multivariate analyses showed a higher late graft survival to be associated with: no acute rejection episodes (risk ratio 0.16, p = 0.0001), age 2-5 years (risk ratio 0.24, p = 0.0007), living donor (risk ratio 0.46, p = 0.017), primary nonrecurrent disease (risk ratio 0.29, p = 0.001), Caucasian race (risk ratio 0.40, p = 0.006). A high half-life was seen with living donor transplant (21.3 years) and the age group 2-5 years (27.5 years). Further, living donor patients with no acute rejection episodes had the best half-life of 37.6 years, while children with hemolytic uremic syndrome, focal segmental glomerulosclerosis or oxalosis had the lowest overall half-life of 5.6 years. This study finds that living donor, no acute rejection episodes, age 2-5 years, Caucasian race and having a disease not prone to recurrence are strong predictors of late graft survival. Hence, preferential use of living donor and prevention of acute rejection episodes in the first year are key variables that can improve long-term renal graft survival in children.  相似文献   
43.
OBJECTIVES: Vasodilator use during cardiopulmonary bypass is important in pediatric cardiac surgery, but the full range of their effects on hemodynamics remains to be clarified. We studied the effects of chlorpromazine, a potent alpha-blocking agent, in neonates. METHODS: Subjects were 60 neonates undergoing arterial switch operations for complete transposition of the great arteries with an intact ventricular septum. Of these, 37 received 2.1 to 6.5 mg/kg of chlorpromazine during cardiopulmonary bypass (CPZ group) and 23 received no vasodilator (control group). We then compared hemodynamic parameters between groups during and early after surgery. RESULTS: The systemic vascular resistance index and mean arterial pressure during cardiopulmonary bypass were significantly lower in the CPZ group (p < 0.05), but systolic pressure 15 minutes after cessation of cardiopulmonary bypass did not differ between groups. The rise in peripheral temperature during rewarming after hypothermia was significantly higher and the acid-base status 40 minutes after cardiopulmonary bypass less acidotic in the CPZ group. Urine output during cardiopulmonary bypass was higher in the CPZ group. CONCLUSIONS: Chlorpromazine effectively counteracts systemic vasoconstriction induced by cardiopulmonary bypass without serious side effects in neonatal cardiac surgery.  相似文献   
44.
OBJECTIVE: Since we developed the procedure in 1996, we have now performed 100 pediatric open heart operations using a lower midline skin incision and a minimal sternotomy approach. METHODS AND RESULTS: To elucidate the benefits of this approach, we analyzed these 100 cases retrospectively. There was no death, and no major complication, caused by this approach, and the resulting scarring in each patient is difficult to be seen under a common undershirt. CONCLUSION: This review shows that the technique of a lower midline skin incision and minimal sternotomy approach is a safe reliable and cosmetically advantageous method for a pediatric cardiac operation.  相似文献   
45.
Background. Extreme hemodilution caused by relatively large prime volumes required for cardiopulmonary bypass in infants causes a dilutional coagulopathy, characterized by low concentrations of fibrinogen and other circulating coagulation factors. Modified ultrafiltration results in hemoconcentration and is associated with decreases in postoperative bleeding and transfusion requirements in children. This study was undertaken to quantify the effect of modified ultrafiltration on concentrations of fibrinogen, plasma proteins, and platelets in infants and small children.

Methods. Twenty patients less than 15 kg were studied. Cardiopulmonary bypass circuits were primed with crystalloid solutions. Red blood cells were added during cardiopulmonary bypass for hematocrits less than 15%. Colloid solutions were not administered. Concentrations of fibrinogen, plasma proteins, and platelets, and hematocrit were measured before cardiopulmonary bypass, before modified ultrafiltration, and after modified ultrafiltration.

Results. Modified ultrafiltration was associated with significant (p < 0.001) increases in hematocrit (19% ± 6% to 31% ± 9%), fibrinogen (65 ± 29 to 101 ± 45 mg/dL), and total plasma proteins (2.7 ± 0.3 to 4.9 ± 0.7 g/dL), but no change (p = 0.129) in platelet count.

Conclusions. We conclude that modified ultrafiltration significantly attenuates the dilutional coagulopathy associated with cardiopulmonary bypass in infants.  相似文献   

46.
Background: Most paediatric cardiac arrest studies have been conducted in the USA, where paramedics provide prehospital emergency care. We wanted to study the outcome of paediatric cardiac arrest patients in an emergency medical system which is based on physician staffed emergency care units.
Methods: We analysed retrospectively the files of 100 prehospital cardiac arrest patients from Southern Finland during a 10-year study period. The patients were less than 16 years of age.
Results: Fifty patients were declared dead on the scene (DOS) without attempted resuscitation, and cardiopulmonary resuscitation (CPR) was initiated in 50 patients. The sudden infant death syndrome was the most common cause of arrest in the DOS patients (68%) as well as in those receiving CPR (36%). Asystole was the initial cardiac rhythm in 70% of the patients in whom CPR was attempted. Resuscitation was successful in 13 patients, 8 of whom were ultimately discharged. Six of the patients survived with mild or no disability and 4 of them had near-drowning aetiology. In multivariate analysis, the short duration of CPR (≤15 min) was the only factor significantly associated with better survival.
Conclusions: Although prehospital care was provided by physicians, the overall rate of survival was found to be equally poor as reported from systems with paramedics. The only major difference between physician- and paramedic-staffed emergency care units is the ability of physicians to refrain from resuscitation already on the scene when prognosis is poor.  相似文献   
47.
The case of a 7-year-old girl with acquired immunodeficiency syndrome treated for 5 years with AZT and intravenous gamma globulin is reported. Shortly before her demise she developed a pulmonary leiomyosarcoma and leiomyoma. Does prolonged survival in pediatric acquired immune deficiency syndrome increase the incidence of secondary malignancies?  相似文献   
48.
Chronic rejection accounted for 32% of all graft losses in 7123 pediatric transplants. In a previous study acute, multiple acute and late acute rejections were risk factors for the development of chronic rejection. We postulated that the recent decrease in acute rejections would translate into a lower risk for chronic rejection among patients with recent transplants. We reviewed our data on patients transplanted from 1995 to 2000, and using multivariate analysis and a proportional hazards model developed risk factors for patients whose grafts had failed due to chronic rejection. A late initial rejection increased the risk of chronic rejection graft failure 3.6-fold (p < 0.001), while a second rejection resulted in further increase of 4.2-fold (p < 0.001). Recipients who received less than 5 mg/kg of cyclosporine at 30 days post-transplant had a relative risk (RR) of 1.9 (p = 0.02). Patients transplanted from 1995 to 2000 had a significantly lower risk (RR = 0.54, p < 0.001) of graft failure from chronic rejection than those who received their transplants earlier (1987-94). Since we were able to demonstrate that there is a decreased risk of chronic rejection graft failure in our study cohort, we would conclude that the goal of future transplants should be to minimize acute rejections.  相似文献   
49.
Objectives:  The aims of this paper are to provide an overview of neuroimaging findings specific to bipolar disorder and suicide, and to consider rational approaches to the design of future in vivo studies in youth at risk.
Methods:  Neuroimaging and related neurobiological literature pertaining to bipolar disorder and suicide in adult and pediatric samples was reviewed in a non-quantitative manner.
Results:  Specific structural and functional brain findings in bipolar disorder are described, where possible in the context of relevant current neurobiological theories of etiology. Diagnostic and prognostic implications are discussed.
Conclusions:  The simultaneous use of complementary neurobiological approaches may be a powerful way of identifying and validating factors reliably associated with bipolar disorder and suicide. A profile of neurobiological markers with which to screen for bipolar disorder and suicide risk may provide for earlier and more accurate diagnosis, perhaps even in the pre- or subsyndromal stages in high-risk youth.  相似文献   
50.
The optimal use of kidneys from small pediatric deceased donors remains undetermined. Using data from the Scientific Registry of Transplant Recipients, 2886 small (< 21 kg) pediatric donors between 1993 and 2002 were identified. Donor factors predictive of kidney recovery and transplantation (1343 en bloc; 1600 single) were identified by logistic regression. Multivariable Cox regression was used to assess the risk of graft loss. The rate of kidney recovery from small pediatric donors was significantly higher with increasing age, weight and height. The odds of transplant of recovered small donor kidneys were significantly higher with increasing age, weight, height and en bloc recovery (adjusted odds ratio = 65.8 vs. single; p < 0.0001), and significantly lower with increasing creatinine. Compared to en bloc, solitary transplants had a 78% higher risk of graft loss (p < 0.0001). En bloc transplants had a similar graft survival to ideal donors (p = 0.45) while solitary transplants had an increased risk of graft loss (p < 0.0001). En bloc recovery of kidneys from small pediatric donors may result in the highest probability of transplantation. Although limited by the retrospective nature of the study, kidneys transplanted en bloc had a similar graft survival to ideal donors but may not maximize the number of successfully transplanted recipients.  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