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   4983篇
  免费   223篇
  国内免费   12篇
耳鼻咽喉   47篇
儿科学   138篇
妇产科学   247篇
基础医学   714篇
口腔科学   109篇
临床医学   360篇
内科学   990篇
皮肤病学   71篇
神经病学   429篇
特种医学   135篇
外科学   686篇
综合类   83篇
一般理论   4篇
预防医学   431篇
眼科学   123篇
药学   299篇
中国医学   16篇
肿瘤学   336篇
  2024年   26篇
  2023年   52篇
  2022年   95篇
  2021年   206篇
  2020年   100篇
  2019年   138篇
  2018年   158篇
  2017年   103篇
  2016年   118篇
  2015年   139篇
  2014年   176篇
  2013年   235篇
  2012年   366篇
  2011年   353篇
  2010年   184篇
  2009年   146篇
  2008年   285篇
  2007年   275篇
  2006年   264篇
  2005年   255篇
  2004年   236篇
  2003年   200篇
  2002年   203篇
  2001年   41篇
  2000年   43篇
  1999年   33篇
  1998年   44篇
  1997年   45篇
  1996年   25篇
  1995年   28篇
  1994年   41篇
  1993年   31篇
  1992年   32篇
  1991年   28篇
  1990年   32篇
  1989年   23篇
  1988年   31篇
  1987年   22篇
  1986年   25篇
  1985年   17篇
  1984年   20篇
  1983年   17篇
  1982年   24篇
  1981年   20篇
  1980年   21篇
  1979年   24篇
  1978年   17篇
  1976年   14篇
  1975年   14篇
  1969年   10篇
排序方式: 共有5218条查询结果,搜索用时 15 毫秒
1.

Background

Unintentional underfeeding is common in patients receiving enteral nutrition (EN), and is associated with increased risk of malnutrition complications. Protocols for EN in critically ill patients have been shown to enhance adequacy, resulting in better clinical outcomes; however, outside of intensive care unit (ICU) settings, the influence of a protocol for EN is unknown.

Objective

To evaluate the efficacy and safety of implementing an EN protocol in a noncritical setting.

Design

Randomized controlled clinical trial.

Participants and settings

This trial was conducted from 2014 to 2016 in 90 adult hospitalized patients (non-ICU) receiving exclusively EN. Patients with carcinomatosis, ICU admission, or <72 hours of EN were excluded.

Intervention

The intervention group received EN according to a protocol, whereas the control group was fed according to standard practice.

Main outcome measures

The proportion of patients receiving ≥80% of their caloric target at Day 4 after EN initiation.

Statistical analyses performed

Student t test or Wilcoxon rank-sum test were used for continuous variables and the difference between the groups in the time to receipt of the optimal amount of nutrition was analyzed using Kaplan-Meier curves.

Results

Forty-five patients were randomized to each group. At Day 4 after EN initiation, 61% of patients in the intervention arm had achieved the primary end point compared with 23% in the control group (P=0.001). In malnourished patients, 63% achieved the primary end point in the intervention group compared with 16% in the control group (P=0.003). The cumulative deficit on Day 4 was lower in the intervention arm compared with the control arm: 2,507 kcal (interquartile range [IQR]=1,262 to 2,908 kcal) vs 3,844 kcal (IQR=2,620 to 4,808 kcal) (P<0.001) and 116 g (IQR=69 to 151 g) vs 191 g (IQR=147 to 244 g) protein (P<0.001), respectively. The rates of gastrointestinal complications were not significantly different between groups.

Conclusions

Implementation of an EN protocol outside the ICU significantly improved the delivery of calories and protein when compared with current standard practice without increasing gastrointestinal complications.  相似文献   
2.
Calcium hydroxide is advocated as an intracanal medication for various purposes, including prevention of posttreatment symptoms. This study assessed whether calcium hydroxide had a pain-controlling effect at different times when compared with no intracanal medication. One hundred forty patients participated. Conditions diagnosed were pulp/periapical pathosis with or without symptoms. At least partial cleaning and shaping was completed. At random, either Ca(OH)2 plus H2O paste or a dry cotton pellet was placed in the canals of half the teeth, respectively. All teeth were temporized with Intermediate Restorative Material. Patients assessed posttreatment pain up to 48 h as none, mild, moderate, or severe. The pain levels in each test group [Ca(OH)2 versus cotton pellet] at each time period were compared statistically with a multiple-regression analysis. There was no significant difference in posttreatment pain between the two groups at any time period or with any diagnosis or symptom. The use of calcium hydroxide as an intracanal medication was unrelated to the incidence and/or severity of posttreatment pain.  相似文献   
3.
The aim of the present study was to evaluate the possible relationship between tobacco smoking and alcohol drinking and the anatomical sites of squamous cell carcinoma (SCC) of the lip and oral cavity. For this purpose, a case-case study has been performed in 690 patients. The study was focused on the relative risk (RR) or developing SCC at various (sub)sites, for smokers and drinkers of alcohol (divided into moderate and heavy users) relative to non-smokers and non-drinkers. Estimates of ratios of these relative risks were obtained. The relative risk associated with tobacco smoking, adjusted for the use of alcohol, appeared to be highest for SCC in the retromolar area, followed by the floor of mouth, whereas the lowest RR was found in the cheek mucosa. For alcohol drinking, adjusted for tobacco smoking, RR of SCC of the floor of mouth was significantly higher than for the tongue, whereas the RR of SCC of the cheek appeared to be lowest. Furthermore, this study suggests that the contrasts between relative risks, observed by anatomical site of oral SCC, are more pronounced for tobacco smoking than for the use of alcohol. The possible local and systemic factors responsible for these variations of susceptibility for tobacco and alcohol within the oral cavity are discussed.  相似文献   
4.
5.
6.
7.
8.
The development of melanoma brain metastasis is largely dependent on mutual interactions between the melanoma cells and cells in the brain microenvironment. Here, we report that the extracellular cysteine protease inhibitor cystatin C (CysC) is involved in these interactions. Microglia-derived factors upregulated CysC secretion by melanoma. Similarly, melanoma-derived factors upregulated CysC secretion by microglia. Whereas CysC enhanced melanoma cell migration through a layer of brain endothelial cells, it inhibited the migration of microglia cells toward melanoma cells. CysC was also found to promote the formation of melanoma three-dimensional structures in matrigel. IHC analysis revealed increased expression levels of CysC in the brain of immune-deficient mice bearing xenografted human melanoma brain metastasis compared to the brain of control mice. Based on these in vitro and in vivo experiments we hypothesize that CysC promotes melanoma brain metastasis. Increased expression levels of CysC were detected in the regenerating brain of mice after stroke. Post-stroke brain with melanoma brain metastasis showed an even stronger expression of CysC. The in vitro induction of stroke-like conditions in brain microenvironmental cells increased the levels of CysC in the secretome of microglia cells, but not in the secretome of brain endothelial cells. The similarities between melanoma brain metastasis and stroke with respect to CysC expression by and secretion from microglia cells suggest that CysC may be involved in shared pathways between brain metastasis and post-stroke regeneration. This manifests the tendency of tumor cells to highjack physiological molecular pathways in their progression.  相似文献   
9.
Allogeneic hematopoietic stem cell transplantation (HSCT) is beneficial for pediatric patients with relapsed or (very) high-risk acute lymphoblastic leukemia (ALL) in remission. A total of 1115 consecutive patients were included in the ALL SCT 2003 BFM study and the ALL SCT 2007 I-BFM study and were stratified according to relapse risk (standard versus high versus very high risk of relapse) and donor type (matched sibling versus matched donor versus mismatched donor). A total of 148 patients (60% boys; median age, 8.7 years; B cell precursor ALL, 75%) were transplanted from mismatched donors, which was defined as either less than 9/10 HLA-compatible donors or less than 5/6 unrelated cord blood after myeloablative conditioning regimen (total body irradiation based, 67%) for high relapse risk (HRR; n?=?42) or very HRR (VHRR) disease (n?=?106). The stem cell source was either bone marrow (n?=?31), unmanipulated peripheral stem cells (n?=?28), T cell ex vivo depleted peripheral stem cells (n?=?59), or cord blood (n?=?25). The median follow-up was 5.1 years. The 4-year rates of overall survival (OS) and event-free survival were 56%?±?4% and 52%?±?4%, respectively, for the entire cohort. Patients transplanted from mismatched donors for HRR disease obtained remarkable 4-year OS and event-free survival values of 82%?±?6% and 80%?±?6%, respectively, whereas VHRR patients obtained values of 45%?±?5% and 42%?±?5% (P?<?.001), respectively. The cumulative incidence of relapse was 29%?±?4% and that of nonrelapse mortality 19%?±?3%. The cumulative incidence of limited and extensive chronic graft-versus-host disease was 13%?±?3% and 15%?±?4%, respectively, among the 120 patients living beyond day 100. Multivariate analysis showed that OS was lower for transplanted VHRR patients (P?=?.002; hazard ratio [HR], 3.62; 95% confidence interval [CI], 1.60 to 8.20) and for patients beyond second complete remission (CR2) versus first complete remission (P?<?.001; HR, 3.68; 95% CI, 1.79 to 7.56); relapse occurred more frequently in patients with VHRR disease (P?=?.026; HR, 3.30; 95% CI, 1.16 to 9.60) and for those beyond CR2 (P?=?.005; HR, 4.16; 95% CI, 1.52 to 10.59). Nonrelapse mortality was not significantly higher for cytomegalovirus-positive recipients receiving cytomegalovirus-negative grafts (P?=?.12; HR, 1.96; 95% CI, .84 to 4.58). HSCT with a mismatched donor is feasible in pediatric ALL patients but leads to inferior results compared with HSCT with better matched donors, at least for patients transplanted for VHRR disease. The results are strongly affected by disease status. The main cause of treatment failure is still relapse, highlighting the urgent need for interventional strategies after HSCT for patients with residual leukemia before and/or after transplantation  相似文献   
10.

Objective

To determine whether stratification of complexity models in congenital heart surgery (RACHS-1, Aristotle basic score and STS-EACTS mortality score) fit to our center and determine the best method of discriminating hospital mortality.

Methods

Surgical procedures in congenital heart diseases in patients under 18 years of age were allocated to the categories proposed by the stratification of complexity methods currently available. The outcome hospital mortality was calculated for each category from the three models. Statistical analysis was performed to verify whether the categories presented different mortalities. The discriminatory ability of the models was determined by calculating the area under the ROC curve and a comparison between the curves of the three models was performed.

Results

360 patients were allocated according to the three methods. There was a statistically significant difference between the mortality categories: RACHS-1 (1) - 1.3%, (2) - 11.4%, (3)-27.3%, (4) - 50 %, (P<0.001); Aristotle basic score (1) - 1.1%, (2) - 12.2%, (3) - 34%, (4) - 64.7%, (P<0.001); and STS-EACTS mortality score (1) - 5.5 %, (2) - 13.6%, (3) - 18.7%, (4) - 35.8%, (P<0.001). The three models had similar accuracy by calculating the area under the ROC curve: RACHS-1- 0.738; STS-EACTS-0.739; Aristotle- 0.766.

Conclusion

The three models of stratification of complexity currently available in the literature are useful with different mortalities between the proposed categories with similar discriminatory capacity for hospital mortality.  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