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   1150篇
  免费   57篇
  国内免费   4篇
耳鼻咽喉   5篇
儿科学   14篇
妇产科学   23篇
基础医学   132篇
口腔科学   18篇
临床医学   70篇
内科学   273篇
皮肤病学   13篇
神经病学   114篇
特种医学   37篇
外科学   238篇
综合类   4篇
预防医学   95篇
眼科学   52篇
药学   64篇
中国医学   2篇
肿瘤学   57篇
  2023年   8篇
  2022年   14篇
  2021年   33篇
  2020年   16篇
  2019年   26篇
  2018年   22篇
  2017年   14篇
  2016年   16篇
  2015年   22篇
  2014年   29篇
  2013年   41篇
  2012年   57篇
  2011年   74篇
  2010年   50篇
  2009年   37篇
  2008年   61篇
  2007年   78篇
  2006年   76篇
  2005年   86篇
  2004年   68篇
  2003年   66篇
  2002年   46篇
  2001年   47篇
  2000年   50篇
  1999年   41篇
  1998年   15篇
  1997年   11篇
  1996年   10篇
  1995年   10篇
  1994年   5篇
  1993年   2篇
  1992年   14篇
  1991年   10篇
  1990年   13篇
  1989年   8篇
  1988年   4篇
  1987年   2篇
  1985年   3篇
  1984年   8篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1978年   2篇
  1977年   2篇
  1976年   1篇
  1972年   2篇
  1971年   1篇
  1970年   2篇
  1966年   1篇
排序方式: 共有1211条查询结果,搜索用时 15 毫秒
21.
Vitamin K antagonists have been shown to be effective in the primary and secondary prevention of systemic and cerebral emboli in patients with cardiac causes of embolism, especially atrial fibrillation. The reduced risk of stroke is greater in secondary prevention, although this reduction is accompanied by an inherent risk of hemorrhagic complications, among which cerebral hemorrhage is especially serious. The therapeutic window of these agents is limited and the best benefit/risk profile is obtained with an INR of between 2 and 3. The anticoagulant effect obtained shows marked variability, requiring frequent clinical and laboratory monitoring of the treatment. The introduction of oral anticoagulants that would aid the administration of these agents with equal or greater efficacy and lower risk is required.  相似文献   
22.
Objective: To determine which parameter of the umbilical arterial cord gas analysis, pH, base deficit (BD) or lactate has a bigger predictive ability for neonatal morbidity at term.

Method: We conducted a four-year retrospective cohort study including all non-anomalous, singleton, vertex, term births with neonatal acidemia (umbilical arterial cord gas pH?≤?7.1). The primary outcomes were a composite neurological morbidity and a composite systemic morbidity. The predictive ability of lactate, BD and pH was compared using receiver operator characteristic (ROC) curves. Optimal cutoff values of lactate, BD and pH were estimated based on their maximal Youden Index.

Results: We identified 466 acidemic neonates who had paired and validated cord blood gas data. The ROC curve analysis revealed that pH, BD and lactate had a similar predictive ability for neurological (AUC: 0.81; 0.78; 0.83, respectively) and systemic neonatal morbidity (AUC: 0.77; 0.82; 0.82, respectively). The combination of pH?≤?7.0 and lactate?≥?7.0?mmol/L presented similar validity to that of pH?≤?7.0 and BD?≥?12?mmol/L, but both were comparable to pH alone.

Conclusions: pH, BD and lactate have similar predictive ability for adverse neonatal outcomes among acidemic neonates. Umbilical arterial lactate could replace BD as a measure of the metabolic component in acidemic neonates. However, neither BD nor lactate demonstrated in this study to improve the predictive ability of pH alone for short-term neonatal outcomes.  相似文献   
23.
24.

Purpose:

To evaluate the predictability of the refractive correction achieved with a positional accommodating intraocular lenses (IOL) and to develop a potential optimization of it by minimizing the error associated with the keratometric estimation of the corneal power and by developing a predictive formula for the effective lens position (ELP).

Materials and Methods:

Clinical data from 25 eyes of 14 patients (age range, 52–77 years) and undergoing cataract surgery with implantation of the accommodating IOL Crystalens HD (Bausch and Lomb) were retrospectively reviewed. In all cases, the calculation of an adjusted IOL power (PIOLadj) based on Gaussian optics considering the residual refractive error was done using a variable keratometric index value (nkadj) for corneal power estimation with and without using an estimation algorithm for ELP obtained by multiple regression analysis (ELPadj). PIOLadj was compared to the real IOL power implanted (PIOLReal, calculated with the SRK-T formula) and also to the values estimated by the Haigis, HofferQ, and Holladay I formulas.

Results:

No statistically significant differences were found between PIOLReal and PIOLadj when ELPadj was used (P = 0.10), with a range of agreement between calculations of 1.23 D. In contrast, PIOLReal was significantly higher when compared to PIOLadj without using ELPadj and also compared to the values estimated by the other formulas.

Conclusions:

Predictable refractive outcomes can be obtained with the accommodating IOL Crystalens HD using a variable keratometric index for corneal power estimation and by estimating ELP with an algorithm dependent on anatomical factors and age.  相似文献   
25.
OBJECTIVES: 1) To analyze the clinical features and outcome of patients with rheumatoid arthritis and pyarthrosis seen in a rheumatology department during a 9-year period; 2) To review the available literature about this association in the last decade. METHODS: From the database of our department, we collected all hospitalized cases of infectious arthritis in native joints between January 1990 and December 1998. In 10 cases (27%), pyarthrosis occurred in patients with rheumatoid arthritis. A detailed analysis of each patient was performed. The literature was reviewed by using MEDLINE from 1990 to 1999. RESULTS: The mean age of patients was 63.2 years; six were female. Most patients had long-standing disease and poor functional class, and all received glucocorticoid treatment. Mean diagnostic delay was 7.3 days. Causative organisms were Staphylococcus aureus (4 cases), gram-negative bacilli (3 cases), anaerobic bacteria (2 cases), and Streptococcus pneumoniae (n = 1). Two patients died. In all but two patients who survived, joint function worsened. CONCLUSIONS: Rheumatoid arthritis is a relevant host-related risk factor for septic arthritis. Pyarthrosis in these patients is associated with considerable morbidity and mortality.  相似文献   
26.
27.
DR, C4, and Bf allotypes in juvenile rheumatoid arthritis   总被引:1,自引:0,他引:1  
HLA-DR, C4, and Bf typing was performed in 99 patients with juvenile rheumatoid arthritis (JRA). DR1 was found with higher frequency in patients with polyarticular JRA than in controls (P less than 0.05). DR3 was more common in patients with fever and/or rash than in those without these manifestations (P less than 0.05). A significant negative association between JRA and C4A6 (P less than 0.05), C4BQ0 (P less than 0.0005), and BfF1 (P less than 0.05) was found. It is possible that a disequilibrium between DR and C4/Bf genes plays a role in the pathogenesis of JRA.  相似文献   
28.
The most cases of splenic marginal zone lymphoma (SMZL) seem to respond favorably to splenectomy. The diagnosis of this lymphoma is mainly based on the recognition of a micronodular pattern of splenic involvement with marginal zone differentiation. However, it is possible to find so-called "marginal zone differentiation" in splenic involvement by other small B-cell lymphomas, particularly mantle cell lymphoma (MCL) and follicular lymphoma. We report a case of blastic MCL, large cell/anaplastic variant with a high level of clinical aggressiveness, showing biphasic cytology and a micronodular pattern which resembles SMZL. A single biopsy corresponding to this case shows two phases of tumoral progression in a MCL, a rare finding in MCL. In conclusion, the differential diagnosis of SMZL must take the possibility of a blastic MCL with biphasic cytology into account, as the case here.  相似文献   
29.
Smokeless tobacco (Snus) is a substance that contains nicotine, which has been placed on World Anti‐Doping Agency's 2014 Monitoring Program. A proliferation of nicotine use in sport has been observed in recent years, but little is known regarding its effects, especially on football players' performance. Therefore, the aim of this study was to assess the effect of Snus on physical performance, heart rate variability, subjective activation, mental fatigue, and perceived readiness before a physical test in non‐smoker, non‐Snus user, amateur football players. Participants were administered either Snus or placebo 40 min prior to a fitness test battery (handgrip test, countermovement jump, agility test, and Yo‐Yo intermittent recovery test). Results showed that Snus intake (compared with placebo) increased perceived mental fatigue level and mental load, and reduced perceived readiness level and heart rate variability. No significant differences between the two experimental conditions were found in either performance in the physical tests or perceived physical fatigue levels. In light of these results, Snus could not be considered an ergogenic substance. On the contrary, based on the extant evidence linking mental load and fatigue with physical performance, we argue that the observed negative effects on mental fatigue, perceived readiness, and heart rate variability should be considered.  相似文献   
30.
Idiopathic nephrotic syndrome (INS) is a multifactorial disease, characterized by proteinuria, hypoalbuminemia, edema and hyperlipidemia. Studies in humans and animal models have associated INS with changes in the immune response. The purpose of this article is to review clinical and experimental findings showing the involvement of the immune response in the pathogenesis of INS. The role of the immune system in INS has been shown by clinical and experimental studies. However, the pattern of immune response in patients with INS is still not clearly defined. Many studies show changes in the dynamics of T lymphocytes, especially the regulatory T cells. Alternatively, there are other reports regarding the involvement of the complement system and B lymphocytes in the pathophysiology of INS. Indeed, none of the immunological biomarkers evaluated were undeniably linked to changes in glomerular permeability and proteinuria. On the other hand, some studies suggest a link between urinary chemokines, such as IL-8/CXCL8 and MCP-1/CCL2, and changes in glomerular permeability and/or the deterioration of glomerulopathies. To understand the pathophysiology of INS, longitudinal studies are clearly needed. The characterization of the profile of the immune response might help the development of specific and individualized therapies, leading to clinical improvement and better prognosis.  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