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   8324篇
  免费   469篇
  国内免费   41篇
耳鼻咽喉   90篇
儿科学   316篇
妇产科学   274篇
基础医学   781篇
口腔科学   285篇
临床医学   797篇
内科学   1920篇
皮肤病学   248篇
神经病学   627篇
特种医学   306篇
外科学   1462篇
综合类   106篇
一般理论   7篇
预防医学   464篇
眼科学   199篇
药学   464篇
中国医学   36篇
肿瘤学   452篇
  2024年   12篇
  2023年   108篇
  2022年   184篇
  2021年   397篇
  2020年   257篇
  2019年   354篇
  2018年   341篇
  2017年   253篇
  2016年   266篇
  2015年   272篇
  2014年   387篇
  2013年   409篇
  2012年   719篇
  2011年   700篇
  2010年   406篇
  2009年   350篇
  2008年   504篇
  2007年   519篇
  2006年   422篇
  2005年   382篇
  2004年   327篇
  2003年   301篇
  2002年   254篇
  2001年   82篇
  2000年   70篇
  1999年   66篇
  1998年   37篇
  1997年   43篇
  1996年   36篇
  1995年   24篇
  1994年   18篇
  1993年   27篇
  1992年   24篇
  1991年   28篇
  1990年   29篇
  1989年   14篇
  1988年   24篇
  1987年   19篇
  1986年   16篇
  1985年   26篇
  1984年   24篇
  1983年   15篇
  1982年   10篇
  1981年   11篇
  1980年   7篇
  1979年   9篇
  1978年   8篇
  1977年   7篇
  1974年   7篇
  1973年   5篇
排序方式: 共有8834条查询结果,搜索用时 15 毫秒
71.
Heart Failure Reviews - An increase in left ventricular volumes between baseline and follow-up imaging is the main criteria for the quantification of left ventricular remodelling (LVR) after...  相似文献   
72.
73.
The patency of a polytetrafluoroethylene (Gortex®) graft 9½ years after coronary artery bypass graft surgery (CABG) is demonstrated. While this material is not commonly used as a conduit because of limited success in the past, this case demonstrates that, given the right circumstances, longterm patency is possible. Since available conduits for CABG are quite often limited, viable alternatives may be lifesaving and require further evaluation. In addition to mechanical considerations such as size, length, and material, anticoagulation and strict management of hyperlipidemia may be critical.  相似文献   
74.
BACKGROUND: Hypercholesterolemia (HC) is a risk factor for renal disease that may activate the angiotensin II type 1 (AT1) receptor and accelerate renal damage. Early diet-induced HC impairs renal perfusion responses, but it is yet unknown whether the AT1 receptor is involved. This study tested the hypothesis that AT1 receptor blockade improved renal perfusion and functional responses in hypercholesterolemic pigs. METHODS: Regional renal hemodynamics and function in vivo were quantified bilaterally in pigs, at baseline and during vasoactive challenge (acetylcholine or sodium nitroprusside), using electron beam computed tomography after 12 weeks of normal (n = 6) or HC diet (n = 6), or HC diet supplemented (100 mg/d) with the AT1-receptor antagonist irbesartan (HC + AT1, n = 6). RESULTS: Basal cortical and medullary perfusion was similar among the groups. Basal tubular function was similar on normal and HC diets, whereas HC + AT1 showed decreased proximal and distal fluid reabsorption. Hypercholesterolemic pigs had blunted cortical perfusion (P = .22) and augmented tubular responses to acetylcholine, whereas on HC + AT1 diet, cortical perfusion (P = .002) and tubular function were similar to normal animals. This was associated with decreased systemic levels of the oxidative stress markers thiobarbituric acid reactive substances. CONCLUSIONS: The AT1 receptor blockade in HC improves renal perfusion and tubular functional responses to endothelium-dependent vasodilators, in association with a decrease in oxidative stress. These results imply involvement of the renin-angiotensin system in the blunted renal cortical perfusion responses observed in HC, and suggest a potential role for these agents in preservation of intrarenal hemodynamics and function in HC.  相似文献   
75.
Abstract:   Thoracic splenosis (TS) is autoimplantation of ectopic splenic tissue in the thoracic cavity that occurs following splenic injury. The majority of cases of TS are asymptomatic and are diagnosed in the course of an evaluation of incidentally discovered pulmonary lesions. Some cases may be difficult to diagnose, especially if features suggesting TS are not recognized. This may lead to an extensive work-up and unnecessary invasive diagnostic procedures including thoracotomy. This case report describes a 40-year-old man, who was diagnosed incidentally with TS, several years after the initial injury. Multiple, asymptomatic, left-sided pleural based lesions associated with a history of thoracoabdominal injury and splenectomy are the key points that should alert suspicion of TS, which can then simply be confirmed by a Tc-99m sulphur colloid radionuclide scan. Most patients are treated conservatively unless they are symptomatic. Physicians must recognize the key features suggesting a diagnosis of TS, order appropriate imaging studies and avoid unnecessary invasive diagnostic procedures.  相似文献   
76.
BACKGROUND: Risk stratification in Brugada syndrome is controversial, especially in asymptomatic individuals. OBJECTIVE: The purpose of this study was to evaluate tissue Doppler echocardiography in risk stratification of Brugada syndrome. METHODS: Patients with Brugada ECG pattern were enrolled in the study. Left ventricular (LV) preejection period was defined as the time interval between onset of the QRS complex and onset of LV lateral wall systolic wave. Right ventricular (RV) preejection period was defined as the time interval between onset of the QRS complex and onset of RV lateral wall systolic wave. Delay in onset of contraction between RV and LV was defined as RV preejection time - LV preejection time [PET((RV-LV))]. RESULTS: Type 1, 2, and 3 Brugada ECG pattern was found in 30, 56, and 31 patients, respectively. PET((RV-LV)) was significantly greater in type 1 Brugada patients (39.2 +/- 3.2 ms) compared with type 2 (5 +/- 0.3 ms) and 3 (5 +/- 0.4 ms) Brugada patients as well as controls (4.6 +/- 0.3 ms, P <.01 for all comparisons). Among type 1 Brugada patients, PET((RV-LV)) was significantly greater in patients who had previous cardiac events compared with asymptomatic subjects (48.2 +/- 4.3 ms vs 29.5 +/- 3.6 ms, P <.05). In the presence of type 1 Brugada ECG pattern, PET((RV-LV)) > or =40 ms identifies patients likely to have cardiac events, with 85.7% sensitivity and 93.7% specificity. CONCLUSION: PET((RV-LV)) is an important risk indicator for Brugada syndrome.  相似文献   
77.
Graft-versus-host disease (GVHD) is a severe disorder and despite therapeutic efforts to decrease its distressing clinical manifestations, treatment is still not optimal. Here we report the results of studies, in which the purine analogue, fludarabine phosphate, was used in an attempt to modify and decrease GVHD after stem cell transplantation, across major histocompatibility barriers for murine leukemia. B-cell leukemia (BCL-1) bearing (BALB/c x C57BL/6) F1 mice received two cycles of fludarabine (0.8 mg/kg) for 5 days every 2 weeks, followed by 400 mg/kg cyclophosphamide i.p. Animals were then transplanted with C57BL/6 precursor cells and the development of leukemia and extent of GVHD was monitored both clinically and histopathologically. In the fludarabine-treated group, only nine of 28 (32%) mice developed leukemia, compared to 25 of 33 (76%) of control animals (P=0.0006 ). Mice treated with fludarabine-containing regimens prior to transplantation also had much less GVHD both clinically and at autopsy, while graft-versus-leukemia appeared to be augmented in the same animals.  相似文献   
78.
OBJECTIVE: The recently introduced Bayer wide‐range C‐reactive protein (wr‐CRP) assay might be relevant for the real‐time low‐cost and online determination of inflammatory bowel disease (IBD) activity. Our aim was to examine whether wr‐CRP can substitute for the Dade Behring high sensitivity C‐reactive protein (hs‐CRP) assay in IBD patients. METHODS: A total of 71 patients with IBD, of whom 48 had Crohn's disease CD and 23 had ulcerative colitis (UC) with various intensities of disease activity participated in the study. The CRP of patients who were under treatment at the Department of Gastroenterology and Liver Diseases were measured using both wr‐CRP and the hs‐CRP. RESULTS: A significant (r = 0.995; P < 0.001) correlation was noted between the hs‐CRP and wr‐CRP measurements for the whole sample as well as for the two diseases, CD (r = 0.994; P < 0.001) and UC (r = 0.997; P < 0.001), which were analyzed separately. CONCLUSION: The Bayer wr‐CRP assay might be a useful low‐cost and real‐time inflammation‐sensitive biomarker in patients with IBD.  相似文献   
79.
80.
Three-dimensional assessment of optically cleared, entire organs and organisms has recently become possible by tissue clearing and selective plane illumination microscopy (“ultramicroscopy”). Resulting datasets can be highly complex, encompass over a thousand images with millions of objects and data of several gigabytes per acquisition. This constitutes a major challenge for quantitative analysis. We have developed post-processing tools to quantify millions of microvessels and their distribution in three-dimensional datasets from ultramicroscopy and demonstrate the capabilities of our pipeline within entire mouse brains and embryos. Using our developed acquisition, segmentation, and analysis platform, we quantify physiological vascular networks in development and the healthy brain. We compare various geometric vessel parameters (e.g. vessel density, radius, tortuosity) in the embryonic spinal cord and brain as well as in different brain regions (basal ganglia, corpus callosum, cortex). White matter tract structures (corpus callosum, spinal cord) showed lower microvascular branch densities and longer vessel branch length compared to grey matter (cortex, basal ganglia). Furthermore, we assess tumor neoangiogenesis in a mouse glioma model to compare tumor core and tumor border. The developed methodology allows rapid quantification of three-dimensional datasets by semi-automated segmentation of fluorescently labeled objects with conventional computer hardware. Our approach can aid preclinical investigations and paves the way towards “quantitative ultramicroscopy”.  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