首页 | 官方网站   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   8356篇
  免费   569篇
  国内免费   81篇
医药卫生   9006篇
  2024年   16篇
  2023年   136篇
  2022年   272篇
  2021年   394篇
  2020年   256篇
  2019年   327篇
  2018年   328篇
  2017年   273篇
  2016年   307篇
  2015年   378篇
  2014年   426篇
  2013年   535篇
  2012年   799篇
  2011年   792篇
  2010年   415篇
  2009年   323篇
  2008年   464篇
  2007年   446篇
  2006年   417篇
  2005年   341篇
  2004年   275篇
  2003年   250篇
  2002年   182篇
  2001年   70篇
  2000年   66篇
  1999年   56篇
  1998年   45篇
  1997年   19篇
  1996年   22篇
  1995年   22篇
  1994年   9篇
  1993年   13篇
  1992年   38篇
  1991年   20篇
  1990年   27篇
  1989年   34篇
  1988年   26篇
  1987年   21篇
  1986年   29篇
  1985年   18篇
  1984年   17篇
  1983年   11篇
  1979年   12篇
  1978年   6篇
  1977年   8篇
  1976年   8篇
  1975年   11篇
  1973年   6篇
  1972年   8篇
  1969年   5篇
排序方式: 共有9006条查询结果,搜索用时 15 毫秒
91.
92.
INTRODUCTION: Biventricular pacing system implantation is a time-consuming and challenging procedure. A critical step in biventricular pacemaker implantation is coronary sinus (CS) cannulation. CS cannulation can be achieved either using dedicated guiding catheters (guiding catheter alone positioning strategy, GCA) or with the aid of an electrophysiology catheter advanced inside the guiding catheter (electrophysiology catheter aided positioning strategy, EPA). AIM OF THE STUDY: To evaluate whether the EPA technique is useful for reducing CS cannulation time compared to a conventional GCA technique. METHODS: Thirty-four consecutive patients were randomly assigned to the GCA (18 patients) or EPA (16 patients) CS cannulation strategy. RESULTS: Time to successful catheterization of CS was 5.0 +/- 2.4 min in the EPA group versus 10.1 +/- 5.4 min in the GCA group p = 0.004. Fluoroscopy time was 4.6 +/- 2.3 min in the EPA group versus 9.2 +/- 4.9 min in the GCA group p = 0.004. Total contrast dye volume to search and engage the CS ostium was 0.0 ml in the EPA group versus 14.3 +/- 3.4 ml in the GCA group p < 0.001. CONCLUSIONS: Cannulation of CS with the adjunct of an electrophysiology catheter to dedicated delivery systems significantly reduces procedural time, fluoroscopy time and contrast dye volume compared to a conventional strategy.  相似文献   
93.
94.

Objectives

Systemic sclerosis (SSc) causes functional and structural microcirculatory dysfunction, affecting also distal extremities. Optical Near-InfraRed Spectroscopy (NIRS) of blood HbO2 saturation (stO2) is able to evaluate O2 delivery/consumption balance in the explored tissue. The NIRS-sensitive camera non-invasively detects stO2 values in superficial tissues, automatically generating 2D-imaging maps in real time. We aimed at testing whether NIRS hand imaging may evaluate peripheral microcirculatory dysfunction and its spatial heterogeneity in SSc patients compared to controls.

Methods

Forty SSc patients (aged 55.1?±?15.6 years) and twenty-one healthy controls (aged 54.3?±?14.5years, p?=?0.89) were studied by palmar hand NIRS-2D imaging. A blood pressure cuff was applied to the forearm and 3 min ischemia was induced. Images were acquired at basal conditions and every 10 seconds during 3 minutes of ischemia and 5 minutes of reperfusion. Five regions of interest were positioned on each fingertip, from the second to the fifth finger and one on the thenar eminence.

Results

A significant difference was found between controls and SSc patients in basal stO2 (84.3?±?7.5?vs. 75.4?±?10.9%, p?<?0.001), minimum stO2 (65.2?±?8.0?vs. 53.4?±?10.1%, p?<?0.001) and time to maximum stO2 during hyperemia (63?±?38?vs. 85?±?49?s, p?<?0.05). Among clinical characteristics, anti-Scl70 antibody positivity, digital ulcers history and smoke exposure affected NIRS parameters, as well as sildenafil and statins therapy. Conversely, no significant differences were found in NIRS-2D values between different nailfold-videocapillaroscopy patterns.

Conclusion

NIRS-2D imaging is a simple, automated tool to non-invasively detect regional microcirculatory impairment in SSc, which seems to add significant functional information to the morphological picture of nailfold-videocapillaroscopy.  相似文献   
95.
96.
Protein kinase A (PKA) is a key regulatory enzyme that, on activation by cAMP, modulates a wide variety of cellular functions. PKA isoforms type I and type II possess different structural features and biochemical characteristics, resulting in nonredundant function. However, how different PKA isoforms expressed in the same cell manage to perform distinct functions on activation by the same soluble intracellular messenger, cAMP, remains to be established. Here, we provide a mechanism for the different function of PKA isoforms subsets in cardiac myocytes and demonstrate that PKA-RI and PKA-RII, by binding to AKAPs (A kinase anchoring proteins), are tethered to different subcellular locales, thus defining distinct intracellular signaling compartments. Within such compartments, PKA-RI and PKA-RII respond to distinct, spatially restricted cAMP signals generated in response to specific G protein-coupled receptor agonists and regulated by unique subsets of the cAMP degrading phosphodiesterases. The selective activation of individual PKA isoforms thus leads to phosphorylation of unique subsets of downstream targets.  相似文献   
97.
We summarize the clinical history and laboratory results following the introduction of tenofovir among 6 patients coinfected with human immunodeficiency virus (HIV) and hepatitis B virus (HBV) who presented with severe liver disease while receiving lamivudine-based highly active antiretroviral therapy. In all cases, the introduction of tenofovir led to a sustained undetectable HBV and HIV loads, with marked clinical and laboratory improvement in liver function. We provide supporting evidence for the role of tenofovir in the management of advanced HBV infection in HIV-positive patients after the development of lamivudine resistance.  相似文献   
98.
99.
Rationale:Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal tumor that is prevalent among children and adolescents. Surgery is the most important therapeutic approach for IMT and complete resection is recommended. Although 50% of IMTs show anaplastic lymphoma kinase (ALK) rearrangements, crizotinib has proven an effective therapeutic approach. However, the genetic landscape of this tumor is still not fully understood and treatment options are limited, especially in the majority of ALK-negative tumors.Patient concerns:We describe the clinical case of a healthy 18-year-old female in whom a pulmonary nodule was incidentally detectedDiagnoses:Following a small increase in the size of the nodule, the patient underwent both 18FDG-PET/CT and 68Ga-PET/CT, resulting in a suspicion of bronchial hamartoma.Interventions:The patient underwent surgery and a salivary gland-like lung tumor was diagnosed.Outcomes:After surgery, the patient was referred to our cancer center, where a review of the histology slides gave a final diagnosis of ALK-negative lung IMT. Given the histology, it was decided not to administer adjuvant therapy and the patient was placed in a 3-monthly follow-up program. The patient is still disease-free 2 years post-surgery.Lessons:Although there is no standard of care for the treatment of IMT, identifying genomic alterations could help to redefine the management of patients with negative-ALK disease. Our review of the literature on IMT and other kinase fusions revealed, in addition to ALK rearrangements, the potential association of ROS1, NTRK, RET, or PDGFR beta alterations with the tumor.  相似文献   
100.
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-23

京公网安备 11010802026262号