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   6093篇
  免费   392篇
  国内免费   16篇
耳鼻咽喉   28篇
儿科学   196篇
妇产科学   139篇
基础医学   1056篇
口腔科学   67篇
临床医学   685篇
内科学   1132篇
皮肤病学   187篇
神经病学   558篇
特种医学   129篇
外科学   498篇
综合类   79篇
一般理论   4篇
预防医学   780篇
眼科学   170篇
药学   313篇
中国医学   17篇
肿瘤学   463篇
  2023年   52篇
  2022年   64篇
  2021年   155篇
  2020年   86篇
  2019年   118篇
  2018年   154篇
  2017年   122篇
  2016年   147篇
  2015年   160篇
  2014年   217篇
  2013年   323篇
  2012年   402篇
  2011年   487篇
  2010年   261篇
  2009年   244篇
  2008年   423篇
  2007年   370篇
  2006年   396篇
  2005年   428篇
  2004年   349篇
  2003年   340篇
  2002年   299篇
  2001年   58篇
  2000年   49篇
  1999年   44篇
  1998年   60篇
  1997年   51篇
  1996年   44篇
  1995年   41篇
  1994年   39篇
  1993年   46篇
  1992年   32篇
  1991年   25篇
  1990年   25篇
  1989年   18篇
  1988年   24篇
  1987年   12篇
  1986年   14篇
  1985年   20篇
  1984年   23篇
  1983年   19篇
  1982年   23篇
  1981年   13篇
  1980年   15篇
  1979年   12篇
  1978年   12篇
  1976年   15篇
  1975年   23篇
  1974年   14篇
  1973年   17篇
排序方式: 共有6501条查询结果,搜索用时 15 毫秒
61.
62.
Objectives: The American Burn Association classifies a burn to the genitalia as a major injury. Isolated burns to the penis, scrotum or vulva are rare as a result of protection provided by the thighs and abdomen. Thus, burned genitalia represent an ominous sign of a more extensive total body surface area burn. Methods: A retrospective analysis of consecutive patients admitted to a Level‐1 Burn Unit with a burn involving the genitalia from January 1995 to December 2009 comprised the study population. Results: A total of 393 patients of 5878 patients (6.7%) admitted to the Burn Unit suffered a burn involving the genitalia, including 253 males (64.4%) and 140 females (35.6%). The median total body surface area was 12% (range 1–100%), the most common cause of genital burn was scald (n = 246, 62.9%) and median length of stay was 9 days (range 1–472 days). A total of 269 patients (68.4%) were discharged to home from the hospital, and in‐hospital mortality was 20.9%. Conclusions: The typical profile for those sustaining a genital burn include younger patients (≤30 years‐of‐age), sustaining a median total body surface area burn of 12% from a scald injury, with extensive genitalia involvement. Length of stay for genital burns is usually extended and, as a result of concomitant injuries, is associated with a 20% in‐hospital death rate.  相似文献   
63.
Objectives: To evaluate aeration/ventilation in saline‐lavaged piglets during a 3‐h follow‐up after a recruitment maneuver (RM)/PEEP titration compared with PEEP 10 cmH2O without a RM. Background: Lung recruitment and PEEP titration are used to find a PEEP preventing repetitive opening/collapsing of lung. Methods: Twenty‐one lung‐lavaged piglets, mean age 7 weeks and mean weight 10 kg; a RM‐group and a PEEP10‐group, were ventilated at PEEP 5 cmH2O (baseline) followed by zero PEEP ventilation. In the RM‐group, tidal elimination of CO2 and dynamic compliance (Cdyn) guided recruitment and PEEP titration, respectively. A final 3‐h ventilation followed using PEEP 2 cmH2O above the first decline of Cdyn and end‐inspiratory pressure (EIP) for a target tidal volume (VT) of 10 ml·kg?1. In the PEEP10‐group, PEEP 10 cmH2O without a RM was used during the final 3‐h ventilation. CT scans and blood gases were repeated every 30 min. Airway pressures, Cdyn and hemodynamics were continuously recorded. Results: Aeration improved without differences between groups. The RM‐group PEEP level of 10 ± 0.6 cmH2O did not differ from the PEEP10‐group. Compared to baseline EIP was lower in the RM‐group after 3‐h ventilation. In both groups, driving pressure (DP) was lower and Cdyn higher than baseline. In the RM‐group, final EIP and DP were lower and Cdyn higher than in the PEEP10‐group. Conclusions: Both RM/PEEP titration and PEEP elevation resulted in improved aeration without differences between groups at the end point. Lung aeration was achieved at lower EIP and DP and higher Cdyn in the RM‐group than in the PEEP10‐group.  相似文献   
64.

Aims

Central venous catheters are essential for the management of pediatric cardiac surgery patients. Recently, an ultrasound-guided access via a supraclavicular approach to the brachiocephalic vein has been described. Central venous catheters are associated with a relevant number of complications in pediatric patients. In this study, we evaluated the frequency of complications of left brachiocephalic vein access compared with right internal jugular vein standard access in children undergoing cardiac surgery.

Methods

Retrospective analysis of all pediatric cases at our tertiary care university hospital over a two-year period receiving central venous catheters for cardiac surgery. Primary endpoint: Frequency of complications associated with central venous catheters inserted via the left brachiocephalic vein vs. right internal jugular vein. Complications were defined as: chylothorax, deep vein thrombosis, sepsis, or delayed chest closure. Secondary endpoints: Evaluation of the insertion depth of the catheter using a height-based formula without adjustment for side used.

Results

Initially, 504 placed catheters were identified. Following inclusion and exclusion criteria, 480 placed catheters remained for final analysis. Overall complications were reported in 68/480 (14.2%) cases. There was no difference in the frequency of all complications in the left brachiocephalic vein vs. the right internal jugular vein group (15.49% vs. 13.65%; OR = 1.16 [0.64; 2.07]), nor was there any difference considering the most relevant complications chylothorax (7.7% vs. 8.6%; OR = 0.89 [0.39; 1.91]) and thrombosis (5.6% vs. 4.5%; OR = 1.28 [0.46; 3.31]). The mean deviation from the optimal insertion depth was left brachiocephalic vein vs. right internal jugular vein 5.38 ± 13.6 mm and 4.94 ± 15.1 mm, respectively.

Conclusions

Among children undergoing cardiac surgery, there is no significant difference between the supraclavicular approach to the left brachiocephalic vein and the right internal jugular vein regarding complications. For both approaches, a universal formula can be used to determine the correct insertion depth.  相似文献   
65.
Growth retardation is a serious side effect of long-term glucocorticoid (GC) treatment. In order to prevent or diminish this deleterious effect, a combination therapy including growth hormone (GH), a stimulator of bone growth, is often recommended. Parathyroid hormone (PTH) and thyroid hormone (T4) are important hormonal regulators of bone growth, and might also be helpful anabolic agents for counteracting the negative effects of GCs. Therefore, we studied the interaction of GCs in combination with a single dose of either PTH or T4 on GC-induced growth retardation. Dexamethasone (Dex) treatment of mice for four weeks induced a significant growth inhibition of body length and weight and weights of several organs. PTH or T4 alone did not affect the normal growth pattern. However, T4 could partially restore the Dex-induced growth inhibition, whereas PTH could not. Although PTH did not affect total body growth, it did affect the height of the proliferative zone, which could be counteracted by Dex. This contrasts with T4 treatment alone or in combination with Dex, which both resulted in a disturbed morphology of the growth plate. IGF-I mRNA, one of the mediators of longitudinal bone growth, was present in proliferative and hypertrophic chondrocytes. However, its expression was not affected by any of the treatments. In conclusion, T4 but not PTH can partially counteract the effects of Dex on general body growth, with possible implications for future treatments of GC-induced growth retardation. Additionally, both T4 and PTH, alone or in combination with Dex, have differential effects on the morphology of the growth plate.This work was presented in part at the IPNA Seventh Symposium on Growth and Development in Children with Chronic Kidney Disease: The Molecular Basis of Skeletal Growth, 1–3 April 2004, Heidelberg, Germany  相似文献   
66.
BACKGROUND: Alveolar macrophages (AMs) are known to be poor antigen-presenting cells, and lack the accessory molecules such as CD40, CD80 or CD86 to activate T cells. The question raised is about the potential changes in phenotypes after lung transplantation, particularly during acute rejection episodes. METHODS: The present study analyzed the phenotype of AMs longitudinally in 45 lung transplant patients, between August 1997 and April 2002, with a follow-up period of 27.2 +/- 2.5 (mean +/- SEM) months. There were 7.7 +/- 0.6 bronchoalveolar lavage (BAL) assessments performed per patient (i.e., 345 BALs), simultaneously with transbronchial biopsies. Transplantation was soon followed by a progressive upregulation of CD40 on 49.7 +/- 8% of AMs during the first month, and this marker remained elevated at 60 +/- 8% after 5 years. RESULTS: Both CD86 and CD80, as well as CD83, a marker of dendritic cells, were enhanced for most AMs during Grade A2 and A3 rejection episodes. A correlation was found between expression of CD83 and CD86, but not between CD1a and CD86. Immunohistology confirmed that CD40-positive cells in the alveoli corresponded to AMs and to some dendritic cells in the basal layers of the airways. In vitro studies showed that harvested AMs with these enhanced accessory molecules remained poor stimulators of allogeneic cells, a phenomenon that may be related to the ongoing immunosuppressive treatments. CONCLUSIONS: AM phenotypes showed marked changes during early or late acute rejection episodes, acquiring CD80, CD83 and CD86, while CD40 expression was further enhanced. This finding may provide clues on how to monitor the tolerance of transplanted lungs and may also provide new insights into the pathophysiology of lung transplantation.  相似文献   
67.
Complement activation plays a key role in mediating apoptosis, inflammation, and transplant rejection. In this study, the role of the complement 5a receptor (C5aR) was examined in human renal allografts and in an allogenic mouse model of renal transplant rejection. In human kidney transplants with acute rejection, C5aR expression was increased in renal tissue and in cells infiltrating the tubulointerstitium. Similar findings were observed in mice. When recipient mice were treated once daily with a C5aR antagonist before transplantation, long-term renal allograft survival was markedly improved compared with vehicle-treatment (75 versus 0%), and apoptosis was reduced. Furthermore, treatment with a C5aR antagonist significantly attenuated monocyte/macrophage infiltration, perhaps a result of reduced levels of monocyte chemoattractant protein 1 and the intercellular adhesion molecule 1. In vitro, C5aR antagonism inhibited intercellular adhesion molecule 1 upregulation in primary mouse aortic endothelial cells and reduced adhesion of peripheral blood mononuclear cells. Furthermore, C5aR blockade markedly reduced alloreactive T cell priming. These results demonstrate that C5aR plays an important role in mediating acute kidney allograft rejection, suggesting that pharmaceutical targeting of C5aR may have potential in transplantation medicine.  相似文献   
68.
Background and aims Occurrence of tumor relapse is frequent in patients with pancreatic cancer despite the absence of residual tumor detectable at primary surgery and in histopathological examination. Therefore, it has to be assumed that current tumor staging procedures fail to identify minimal amounts of disseminated tumor cells, which might be precursors of subsequent metastatic relapse. The aim of this study was to assess the prognostic impact of minimal tumor cell spread detected in lymph nodes classified as “tumor-free” in routine histopathologic evaluation. Materials and methods A total of 154 “tumor-free” lymph nodes from 59 patients with pancreatic cancer who underwent intentionally curative tumor resection were examined by immunohistochemistry for disseminated tumor cells. Results Fifty (32.5%) of the “tumor-free” lymph nodes obtained from 36 (61%) patients displayed disseminated tumor cells. Multivariate survival analysis revealed that the presence of disseminated tumor cells in “tumor-free” lymph nodes is an independent prognostic factor for both a significantly reduced relapse-free survival (p = 0.03) and overall survival (p = 0.02). Conclusions The frequent occurrence and prognostic impact of immunohistochemically identifiable disseminated tumor cells in lymph nodes of patients with operable pancreatic cancer supports the need for a refined staging system of excised lymph nodes, which should include immunohistochemical examination.  相似文献   
69.
Bloch MB  Dyer RA  Heijke SA  James MF 《Anesthesia and analgesia》2002,94(3):523-8; table of contents
We compared continuous IV tramadol as an alternative to neuraxial or systemic opioids for the management of postthoracotomy pain in a prospective, randomized, double-blinded, controlled study. General anesthesia was supplemented by thoracic epidural analgesia with 0.25% bupivacaine. At rib approximation, patients received one of the following: IV tramadol (150-mg bolus followed by infusion, total 450 mg/24 h, n = 29), epidural morphine (2 mg, then 0.2 mg/h, n = 30), or patient-controlled analgesia (PCA) morphine only (n = 30). All patients received PCA morphine and rescue morphine as necessary postoperatively. For the first 24 h, pain and sedation scores and respiratory, cardiovascular, and side effect measures were monitored. There was no significant difference in pain scores and PCA morphine use between tramadol and epidural morphine. Pain scores at rest and on coughing were lower in the Tramadol and Epidural Morphine groups than in the PCA Morphine group at various time points over the first 12 h. The Tramadol and Epidural Morphine groups used significantly less hourly PCA morphine than the PCA Morphine group at specific time points in the first 10 h. Vital capacities in the Tramadol group were significantly closer to baseline values at the 20-h point than in the PCA Morphine group. We conclude that an intraoperative bolus of tramadol followed by an infusion was as effective as epidural morphine and avoided the necessity of placing a thoracic epidural catheter. IMPLICATIONS: A prospective, randomized, double-blinded, placebo-controlled study of postthoracotomy pain relief showed that IV tramadol in the form of a bolus followed by continuous infusion was as effective as epidural morphine. The use of tramadol avoids the necessity of placing a thoracic epidural catheter.  相似文献   
70.
Natural progression of gait in children with cerebral palsy   总被引:16,自引:0,他引:16  
Twenty-eight children with cerebral palsy had two gait analyses an average of 4.4 years apart with no surgical intervention between the tests. The effects of growth and age were examined using three-dimensional kinematics, temporal and stride parameters, and clinical examination measures. Kinematic changes showed decreases in hip, knee, and ankle sagittal plane ranges of motion (ROM), peak hip flexion in swing, and peak knee flexion over time. Temporal and stride parameters showed declines in timing of toe off, cadence, and walking velocity. Clinical measures showed declines in hip abduction ROM (knees flexed and extended), popliteal angle, and sagittal plane ankle ROM (knees flexed and extended). Overall results showed that gait function in these individuals with cerebral palsy decreased longitudinally with respect to temporal/stride measures, passive ROM, and kinematic parameters compared with a group of individuals who had had orthopaedic intervention.  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