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   9468篇
  免费   608篇
  国内免费   127篇
耳鼻咽喉   14篇
儿科学   619篇
妇产科学   984篇
基础医学   584篇
口腔科学   16篇
临床医学   2152篇
内科学   1620篇
皮肤病学   40篇
神经病学   72篇
特种医学   101篇
外科学   1107篇
综合类   1300篇
预防医学   887篇
眼科学   5篇
药学   477篇
  7篇
中国医学   84篇
肿瘤学   134篇
  2023年   221篇
  2022年   186篇
  2021年   452篇
  2020年   348篇
  2019年   340篇
  2018年   309篇
  2017年   388篇
  2016年   362篇
  2015年   339篇
  2014年   684篇
  2013年   709篇
  2012年   516篇
  2011年   596篇
  2010年   505篇
  2009年   437篇
  2008年   410篇
  2007年   463篇
  2006年   380篇
  2005年   355篇
  2004年   319篇
  2003年   244篇
  2002年   219篇
  2001年   198篇
  2000年   183篇
  1999年   127篇
  1998年   116篇
  1997年   89篇
  1996年   78篇
  1995年   77篇
  1994年   80篇
  1993年   56篇
  1992年   44篇
  1991年   44篇
  1990年   28篇
  1989年   36篇
  1988年   33篇
  1987年   19篇
  1986年   23篇
  1985年   25篇
  1984年   19篇
  1983年   17篇
  1982年   23篇
  1981年   21篇
  1980年   16篇
  1979年   9篇
  1978年   8篇
  1977年   8篇
  1976年   15篇
  1974年   6篇
  1973年   7篇
排序方式: 共有10000条查询结果,搜索用时 718 毫秒
1.
2.
Comprehensive evidence regarding the treatment of non-anaemic iron deficiency in patients undergoing valvular heart surgery is lacking. This study aimed to investigate the association between non-anaemic iron deficiency and postoperative outcomes in these patients. We retrospectively analysed 321 patients of which 180 (56%) had iron deficiency (defined as serum ferritin < 100 ng.ml-1 or < 300 ng.ml-1 with transferrin saturation < 20%). While the iron-deficient group had lower pre-operative haemoglobin levels than the non-iron deficient group (median (IQR [range]) 134 (127–141 [120–172]) g.l-1, 143 (133–150 [120–179]) g.l-1, p = 0.001), there was no between-group difference in allogeneic red blood cell transfusion. Median (IQR [range]) days alive and out of hospital at postoperative day 90 was 1 day shorter in the iron-deficient group (80 (77–82 [9–85]) days vs. 81 (79–83 [0–85]) days, p = 0.026). In multivariable analysis, only cardiopulmonary bypass duration (p = 0.032) and intra-operative allogeneic red blood cell transfusion (p = 0.011) were significantly associated with reduced days alive and out of hospital at postoperative day 90. Iron deficiency did not exert any adverse influence on secondary outcomes except length of hospital stay. Our findings indicate that non-anaemic iron deficiency alone is not associated with adverse effects in patients undergoing valvular heart surgery when it does not translate into an increased risk of allogeneic transfusion.  相似文献   
3.
Objective: To determine whether packed red blood cell (PRBC) transfusion affects post-prandial superior mesenteric artery blood flow velocities (SMA BFVs) in very-low birth weight (VLBW) neonates and if so, at what time point after transfusion restoration of previous SMA BFV patterns occurs.

Design/Methods: VLBW pre-term neonates, older than 14 days and tolerating bolus enteral feedings administered every 3?h were enrolled in this prospective observational study. Pulsed Doppler ultrasound was used to measure pre- and post-prandial (at 45?min) time-averaged mean, peak and end diastolic velocities (TAMV, PSV, EDV) immediately before and after 15?ml/kg of PRBC transfusion was given over 3?h; patent ductus arteriosus (PDA) status was also evaluated. Subsequent pre- and post-prandial SMA BFVs were recorded 24 and 48?h after the transfusion.

Results: Pre- and post-prandial measurements were obtained for 21 out of 25 enrolled infants. Post-prandial SMA BFVs were attenuated during the feedings immediately after transfusion; at 24 and 48?h after transfusion, changes in post-prandial SMA BFVs were similar to those measured prior to transfusion; the presence of the PDA did not affect results.

Conclusions: PRBC transfusion blunted SMA BFV responses to feedings immediately after the transfusion with normalization observed 24?h post-transfusion.  相似文献   
4.
5.
6.
PurposeThe aim of this study was to determine how female age at the end of the reproductive spectrum effects success of natural cycle intrauterine insemination (IUI) or IUI in combination with ovarian stimulation.MethodsWe performed a retrospective cohort study of women 43 years of age and older at the time of IUI in a single academic fertility center between January 2011 and March 2018. Primary outcomes were both pregnancies and live births per cycle of IUI. Data are presented as percentage or mean ± SD. Fisher exact and chi-squared analyses were performed.ResultsThere were 9334 IUI cycles conducted during the study period. Of these cycles, 325 IUIs (3.5%) were for women aged 43 years and over at the time of insemination (43.6 ± 0.8, range 43 to 47 years). Analysis of these 325 IUI cycles revealed 5 biochemical pregnancies (1.5%) and only 1 live birth (0.3%). The pregnancy rate did not differ between IUIs using donor sperm (N = 1/49, 2.0%) compared to IUIs with partner sperm (N = 4/276, 1.4%). The pregnancy rate did not differ between IUIs with gonadotropins (N = 2/211, 0.9%), clomiphene or letrozole (N = 2/78, 2.6%), or natural cycle (N = 1/36, 2.8%).ConclusionsThe use of intrauterine inseminations in women 43 years of age and older is an ineffective treatment strategy. This is irrespective of the use of ovarian stimulation or donor sperm. Costly gonadotropin injections did not increase the chance of pregnancy nor did oral medication when compared to natural cycle IUIs.  相似文献   
7.
IntroductionAlthough blood transfusion is common in burns, data are lacking in appropriate transfusion thresholds. It has been reported that a restrictive blood transfusion policy decreases blood utilization and improves outcomes in critically ill adults, but the impact of a restrictive blood transfusion policy in burn patients is unclear. We decided to investigate the outcome of decreasing the blood transfusion threshold.Material and methodsEighty patients with TBSA > 20% who met our inclusion criteria were included. They were randomly divided into control and intervention groups. The intervention group received packed cells only when Hemoglobin declined to less than 8 g/dL at routine laboratory evaluations. While the control group received packed-cell when hemoglobin was declined to less than 10 g/dl. The total number of the received packed cell before, during and after any surgical procedure was recorded. The outcome was measured by the evaluation of the infection rate and other complications.ResultThe mean hemoglobin level before transfusion was 7.7 ± 0.4 g/dL in the restrictive group and 8.8 ± 0.7 g/dL in the liberal group. The mean number of RBC unit transfusion per patient in the restrictive group was significantly lower than the traditional group (3.28 ± 2.2 units vs. 5.9 ± 3.7 units) (p-value = 0.006). The total number of RBC transfused units varied significantly between the two groups (p-value = 0.014). The number of transfused RBC units outside the operation room showed a significant difference between groups (restrictive: 2.8 ± 1.4 units vs. liberal: 4.4 ± 2.6 units) (p = 0.004). We did not find any significant difference in mortality rate or other outcome measures between groups.ConclusionApplying the restrictive transfusion strategy in thermal burn patients who are highly prone to all kinds of infection, does not adversely impact the patient outcome, and results in significant cost savings to the institution and lower rate of infection. We conclude that the restrictive transfusion practice during burn excision and grafting is well tolerated and effective in reducing the number of transfusions without increasing complications.Clinical Trial Registration ReferenceIRCT20190209042660N1.  相似文献   
8.
9.
10.
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