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   15732篇
  免费   1331篇
  国内免费   480篇
医药卫生   17543篇
  2023年   153篇
  2022年   205篇
  2021年   592篇
  2020年   320篇
  2019年   428篇
  2018年   424篇
  2017年   376篇
  2016年   386篇
  2015年   540篇
  2014年   631篇
  2013年   693篇
  2012年   1132篇
  2011年   1199篇
  2010年   716篇
  2009年   603篇
  2008年   876篇
  2007年   850篇
  2006年   819篇
  2005年   771篇
  2004年   694篇
  2003年   598篇
  2002年   520篇
  2001年   464篇
  2000年   401篇
  1999年   396篇
  1998年   158篇
  1997年   164篇
  1996年   190篇
  1995年   152篇
  1994年   113篇
  1993年   91篇
  1992年   196篇
  1991年   184篇
  1990年   158篇
  1989年   141篇
  1988年   132篇
  1987年   110篇
  1986年   108篇
  1985年   103篇
  1984年   78篇
  1983年   73篇
  1982年   57篇
  1981年   56篇
  1980年   49篇
  1979年   62篇
  1978年   50篇
  1977年   34篇
  1975年   27篇
  1974年   44篇
  1968年   25篇
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
71.
Intracellular pH (pHi) of cultured bovine trabecular cells was measured using video-imaging techniques with a pH-sensitive intracellular fluorescent dye, BCECF. In bicarbonate-rich Ringer at pH 7.4, pHi was 7.29 +/- 0.03 (+/- SEM, n = 12 monolayers, 120 cells sampled). Exposure to 20 mM NH4Cl immediately alkalinized pHi: replacement with a Na(+)-rich solution acidified pHi before recovery to resting levels. When NH4Cl was replaced by a low Na+ solution, acidification was sustained but pHi recovery occurred after Na(+)-rich solution. A pHi of 7.11 +/- 0.02 (n = 2 monolayers, 20 cells) occurred in pH 6.8 and pHi was 7.72 +/- 0.03 (n = 2 monolayers, 20 cells) in pH 8.0. Amiloride (1 mM) acidified pHi but DIDS (1 mM) treatment, HCO3(-)-free condition, 1 mM ouabain, 50 mM K+, and 2 mM BaCl2 failed to change pHi. Hydrogen peroxide (1 mM) acidified pHi but no change occurred with 50 microM. Trabecular cells possess an Na+/H+ exchanger similar to that in other cell types.  相似文献   
72.
BACKGROUND: This study investigated the utility of the alveolar - arterial oxygen pressure difference (AaDO (2)) in predicting the short-term prognosis of acute pulmonary embolism (PE). METHODS AND RESULTS: This study retrospectively enrolled 114 consecutive patients with acute PE, diagnosed by either spiral computed tomography or high probability ventilation - perfusion lung scans. During the first 24 h of admission, all patients had initial artery blood gas collected under room air. Patient exclusion criteria were chronic lung disease, septic emboli, and moderate and low probability lung scans. Patients were assigned to 2 groups based on either 30-day death or a 30-day composite event. Receiver operating characteristic analyses was used to determine the AaDO(2) cut-off value for predicting primary and composite endpoints. Statistical analysis demonstrated significant differences in AaDO(2) between the 30-day composite endpoint group and the 30-day composite event-free survival group (p=0.012). The AaDO(2) had a strong trend between the 30-day death group and the survival group (p=0.062). The best cut-off value for AaDO(2) was 53 mmHg and using this, the positive predictive value for 30-day death was 25% and the negative predictive value was 92%. For the 30-day composite endpoint, the positive predictive value for AaDO(2) was 35%, and the negative predictive value was 84%. In this study, thrombocytopenia was also an indicator of poor prognosis for patients with acute PE. CONCLUSION: The AaDO(2) measurement is a highly useful and simple measurement for predicting short-term prognosis in patients with acute PE. It has high negative predictive value and moderate positive predictive value for 30-day death and 30-day composite event. Aggressive thrombolytic treatment strategies should be considered for patients with an initial poor prognostic parameter (ie, AaDO(2) >or=53 mmHg).  相似文献   
73.
目的 探讨计算机体层成像多平面重建(CTMPR)在评价椎间融合中的作用,寻找定量评价椎间融合的新方法.方法 13例行腰椎间融合的患者术后1周、3个月、6个月行CTMPR,行椎间融合器(Cage)内植骨CT值定量测量.结果 术后1周Cage内植骨CT值为(619.52±26.97)Hu,术后3个月为(628.69±42.60)Hu,术后6个月为(657.77±37.43)Hu.术后1周与术后3个月相比无显著性差异,与术后6个月相比有显著性差异.结论 CT值的测量在椎间融合的判断中具有高准确性.  相似文献   
74.
储兆瑞 《中国性科学》2004,13(12):37-37
一日,我接到一位女土的咨询电话,她希望我能解释一下为什么每次过性生活时,丈夫射精她没有感觉.这是一个有关提高夫妻性爱质量的问题. 一般来说,夫妻在做爱过程中,丈夫射精妻子都会有所感觉.要么妻子感到丈夫急促的喘气声,身体激烈地晃动,小腹有紧张感;要么妻子感到阴道中有一股液体暖流;要么妻子的阴道口出现收缩感,随之带来快感乃至达到性高潮妻子在丈夫射精时没感觉,一般表现为以下几种情况.  相似文献   
75.
BACKGROUND: Steroid-induced rosacea-like eruption is characterized by facial rosacea-like dermatitis in patients that have been treated with topical steroids for relatively long periods. OBJECTIVE: To evaluate the efficacy and tolerability of 1% pimecrolimus topical cream for steroid-induced rosacea-like eruption. METHODS: In an open-label pilot study, 40 patients were enrolled and instructed to apply 1% pimecrolimus cream twice daily for 6 weeks. Patients were evaluated by a rosacea clinical score, investigator's global assessment, overall erythema severity, and tolerability at weeks 0, 2, and 6. RESULTS: In 35 patients, the rosacea clinical score decreased significantly from 16.0+/-4.3 at baseline to 8.1+/-3.3 at week 2 and 4.2+/-2.5 at week 6 (P<0.0001). Investigator's global assessment was 4.1+/-1.1 (baseline), then decreased to 1.4+/-0.8 (week 2) and 0.5+/-0.6 (week 6) (P<0.0001). By week 6, 48.6% of the patients were clear. Overall erythema severity was 2.4+/-0.7 (baseline), 0.9+/-0.4 (week 2), and 0.3+/-0.4 (week 6) (P<0.0001). Cutaneous adverse events (local burning, stinging, and itching) occurred in 17.5%. CONCLUSION: Pimecrolimus cream might be efficacious, safe, and well tolerated for steroid-induced rosacea-like eruption. The small sample size and open label nature of this study is its limitation. Further double-blind, vehicle-controlled studies are needed.  相似文献   
76.
BACKGROUND AND PURPOSE: Nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection is difficult to control. Due to a dramatic increase in the nosocomial MRSA infection rate at our hospital from 2000 to 2001, this study was conducted to identify the source of these infections and the effectiveness of control measures. METHODS: 179 healthcare workers (HCWs) were screened for carriage of MRSA. Starting in April 2001, all patients with MRSA infection or colonization were put in strict contact and cohort isolation. The bacterial isolates of HCW carriers and patients with MRSA infection from April 2001 to September 2001 were subjected to antimicrobial susceptibility testing by disk-diffusion method and molecular typing by pulsed-field gel electrophoresis (PFGE). RESULTS: Fifteen HCWs were found to be carriers of MRSA. They were all given topical mupirocin treatment. After these interventions, the nosocomial MRSA infection rate decreased from 1.23 to 0.53 per 1000 patient-days. All 61 MRSA isolates available for antimicrobial susceptibility testing and molecular typing were multidrug resistant. PFGE study revealed 2 predominant types, type C and type Y, comprising 36 and 12 isolates, respectively. CONCLUSIONS: The current study demonstrates the importance of measures to control nosocomial MRSA infections in hospitals that already have a high incidence of endemic MRSA infection. Elimination of carriage by healthcare workers, and strict contact and cohort isolation are the main effective measures.  相似文献   
77.
The purpose of this work was to evaluate the efficacy of labeling human mesenchymal stem cells (hMSCs) by ionic superparamagnetic iron oxide (SPIO) without a transfection agent and verifying its capability to be detected with clinical 1.5 T magnetic resonance (MR) at the single-cell level. Human hMSCs were incubated for 24 h with an ionic SPIO, Ferucarbotran. The labeling efficiency of hMSCs was determined by iron content measurement spectrophotometrically, and the influence of labeling on cell behavior was ascertained by examination of cell viability using the trypan blue exclusion method, cell proliferation analysis using MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, mitochondrial membrane potential (MMP) change, differentiation capacity, and reactive oxygen species (ROS) production measured by dichlorofluorescein diacetate (DCFDA) fluorescent probe. Labeled hMSCs were scanned under 1.5 T MRI with three-dimensional (3D) and two-dimensional (2D) T(2)-weighted gradient echo (GRE) pulse sequences. Human hMSC labeling without transfection agent was efficient. The iron content in hMSCs was 23.4 pg Fe/cell. No significant change was found in viability, proliferation, MMP change, ROS production, or differentiation capacity. About 45.2% of the hMSCs could be detected using 1.5 T MRI at the single cell level with 3D GRE and four repetitions.  相似文献   
78.
全膝置换术治疗膝关节创伤性关节炎   总被引:5,自引:4,他引:1  
目的探讨全膝置换术(TKA)在膝关节创伤性关节炎治疗中的特点。方法对8例膝关节严重创伤后形成的骨性关节炎施行了TKA手术,术中采用植骨、加装金属垫片的方法修复塌陷的胫骨平台,对内、外翻不稳的膝关节选择了CCK假体代偿由侧副韧带损伤引起的不完全功能缺失,严重者甚至使用旋转型铰链膝,其他还有通过后方的软组织松解等技术来增加关节活动度。结果采用HSS膝关节评分系统,8例由术前的平均42分上升至术后的平均88分(P<0.05),关节活动度由术前的平均76°升至术后的平均106°(P<0.05)。所有患者随访至少1年以上,平均2.1年,随访结束时膝关节评分平均82分(P<0.05),关节活动度平均93°(P<0.05)。结论根据膝关节创伤性关节炎的损伤特点因人而异地选择合适的TKA手术方案可以获得满意的结果,术中注意防止因骨折畸形愈合所导致的技术上的失误。  相似文献   
79.
We report a rare case of neonatal biventricular repair of a right interrupted aortic arch (type B), with an aberrant left subclavian artery, ventricular septal defect and retroaortic innominate vein in a 4-week-old, 2.7 kg neonate with DiGeorge syndrome. The patient had an unremarkable postoperative recovery. We discuss the anatomy of this rare congenital anomaly, its surgical implications and issues surrounding the adequacy of the left ventricular outflow tract.  相似文献   
80.
Neurological disorders induced by long-term exposure to organic solvents typically have a slowly progressive clinical course, which may be arrested or even reversed following discontinuation of exposure. We report an unusual case of rapidly progressive toxic leukoencephalomyelopathy in a 29-year-old man who had worked at a chemical factory that used toluene for the manufacture of nylon 66 for 5 years. He presented with progressive weakness of legs, recurrent seizures, and cognitive decline. Widespread white-matter changes in the brain and spinal cord, and myelodysplastic syndrome were noted. He died 6 months after the onset of his symptoms, and autopsy showed discrete multifocal demyelination and necrosis in the central nervous system, and dysplastic cells of erythroid, myeloid, and megakaryotic lineages in blood vessels. The co-occurrence of leukoencephalomyelopathy and myelodysplastic syndrome highlights the vulnerability of the white matter and bone marrow to injury from organic solvents. Intravascular congestion of dysplastic hematopoietic cells might have led to his unusually rapid progression of leukoencephalomyelopathy.  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-23

京公网安备 11010802026262号