全文获取类型
收费全文 | 1380篇 |
免费 | 19篇 |
国内免费 | 26篇 |
专业分类
教育 | 579篇 |
科学研究 | 123篇 |
体育 | 469篇 |
综合类 | 237篇 |
信息传播 | 17篇 |
出版年
2022年 | 3篇 |
2021年 | 18篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 14篇 |
2015年 | 25篇 |
2014年 | 68篇 |
2013年 | 103篇 |
2012年 | 80篇 |
2011年 | 83篇 |
2010年 | 44篇 |
2009年 | 40篇 |
2008年 | 74篇 |
2007年 | 98篇 |
2006年 | 105篇 |
2005年 | 98篇 |
2004年 | 92篇 |
2003年 | 67篇 |
2002年 | 72篇 |
2001年 | 52篇 |
2000年 | 54篇 |
1999年 | 34篇 |
1998年 | 26篇 |
1997年 | 28篇 |
1996年 | 24篇 |
1995年 | 15篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 12篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 3篇 |
排序方式: 共有1425条查询结果,搜索用时 218 毫秒
141.
急性耐力游泳与静电场对大鼠自由基水平的影响 总被引:2,自引:0,他引:2
分析了0.3、0.6、0.8、1.0、1.2kV/cm静电场作用对应激耐力游泳大鼠血液自由基水平的影响。结果:一次急性耐力性游泳训练,并经适宜的静电场处理,可加速大鼠体内自由基的消除,提高体内抗自由基酶类活性,对加速疲劳机体的恢复具有积极的作用。 相似文献
142.
跑台运动与负重游泳致大鼠力竭性疲劳时心肌骨骼肌组织学变化特征观察 总被引:2,自引:0,他引:2
】通过对大鼠跑台运动和负重游泳致力竭性疲劳时血乳酸的测定及对心肌、骨骼肌组织学损伤程度的观察,研究糖酵解供能条件下不同运动致力竭性疲劳时,心肌、骨骼肌组织学变化特征及致疲劳原因。结果表明,力竭性疲劳时,与游泳组相比,跑台组大鼠心肌和骨骼肌的组织学损伤相对较少,且血乳酸浓度也低于游泳组(P<0.01)。这提示,不同的运动方式对疲劳进程有不同的影响,并且在此运动模型中,血乳酸可能是引起疲劳性损伤的重要因素 相似文献
143.
古典式青年摔跤运动员大强度训练期部分生化指标的监测研究 总被引:4,自引:0,他引:4
采用测试法,跟踪监测古典式青年摔跤运动员大强度训练期间部分生化指标。结果显示:血红蛋白在训练初期明显降低,是反映摔跤训练强度和运动员产生适应的敏感指标;训练期间的血尿素、血清肌酸激酶的“恢复值”可作为医务监督的重要参考指标;血清睾酮、血清皮质醇及其比值用作评价运动员机能状况。 相似文献
144.
BackgroundIndividuals with diabetes have greater central arterial stiffness, wave reflections, and hemodynamics, all of which promote the accelerated cardiovascular pathology seen in this population. Acute aerobic exercise has been shown to be an effective strategy for reducing central arterial stiffness, wave reflections, and hemodynamics in healthy individuals; however, the effects of acute aerobic exercise in reducing these outcomes is not well established in people with diabetes. Recently, implementation of high-intensity interval exercise (HIIE) has shown superior improvements in cardiovascular health outcomes when compared to traditional aerobic exercise. Yet, the effect of HIIE on the aforementioned outcomes in people with diabetes is not known. The purpose of this study was to (i) describe the central arterial stiffness, wave reflections, and hemodynamic responses to a bout of HIIE and moderate-intensity continuous exercise (MICE) in adults with diabetes; and (ii) compare the effects of HIIE and MICE on the aforementioned outcomes.MethodsA total of 24 adult men and women (aged 29–59 years old) with type 1 (n = 12) and type 2 (n = 12) diabetes participated in a randomized cross-over study. All participants completed the following protocols: (i) HIIE: cycling for 4 × 4 min at 85%–95% of heart rate peak (HRpeak), interspersed with 3 min of active recovery at 60%–70%HRpeak; (ii) MICE: 33 min of continuous cycling at 60%–70%HRpeak; and (iii) control (CON): lying quietly in a supine position for 30 min.ResultsA significant group × time effect was found for changes in central systolic blood pressure (F = 3.20, p = 0.01) with a transient reduction for the HIIE group but not for the MICE or CON groups. There was a significant group × time effect for changes in augmentation index at a heart rate of 75 beats/min (F = 2.32, p = 0.04) with a decrease following for HIIE and MICE but not for CON. For all other measures of central arterial stiffness and hemodynamics, no significant changes were observed (p > 0.05).ConclusionA bout of HIIE appears to lead to a greater transient reduction in central systolic blood pressure than the reduction observed following MICE; however, both HIIE and MICE improved augmentation index at a heart rate of 75 beats/min in people with diabetes. There was no significant difference in response to HIIE and MICE in all outcomes. This provides preliminary evidence on the role of HIIE on such outcomes in people with diabetes. 相似文献
145.
Cuhadar S Atay A Koseoglu M Dirican A Hur A 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2012,22(2):202-214
Introduction
The collected and shipped blood samples are exposed to a various extra-analytical factors prior to analysis. The aim of the study was to determine the stability of analytes in serum gel tubes and plain tubes exposed to a range of storage temperatures and times after centrifugation.Materials and methods:
Fifteen healthy volunteers were recruited and venous blood was collected into four tubes, two with and two without gel separator. Analyzing the baseline samples in 30 min, all were stored at 4ºC or 24ºC for 6, 12, 18, 24, 30, 36, 48 and 72 hours and 1 week. Sixteen biochemical anaytes were measured on each sample. Variations remained under the desirable bias considered as clinically insignificant.Results:
On day three, most analytes remained stable including albumin, protein, creatinine, cholesterol, triglycerides, gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), alanine aminotransferase (ALT), creatine kinase (CK), lactate dehydrogenase (LD) regardless of tube types. Glucose concentration decreased markedly (P = 0.001) beginning from the first hours of storage in plain serum. The stability maximized for the analytes including glucose, total bilirubin, urea nitrogen (BUN), uric acid stored at 4 ºC in gel tubes. Aspartate aminotransferase (AST) activity increased significantly (P = 0.002) up to 48-h, however bias was not significant clinically. High density lipoprotein (HDL) concentration was stable in gel tubes at 24 ºC, in plain tubes at 4 ºC stored up to 36-h.Conclusion:
Serum gel or non-gel tubes might be used interchangeably for 11 analytes chilled or at 24 ºC, whereas some restrictions must be applied for glucose, AST, BUN, HDL, and uric acid. 相似文献146.
Simundic AM Lippi G 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2012,22(2):145-149
Preanalytical phase is the most vulnerable part of the total testing process and is considered to be among the greatest challenges to the laboratory professionals. However, preanalytical activities, management of unsuitable specimens and reporting policies are not fully standardized, nor harmonized worldwide. Several standards related to blood sampling and sample transportation and handling are available, but compliance to those guidelines is low, especially outside the laboratory and if blood sampling is done without the direct supervision of the laboratory staff. Furthermore, for some most critical procedures within the preanalytical phase, internationally accepted guidelines and recommendations as well as related quality measures are unfortunately unavailable. There is large heterogeneity in the criteria for sample rejection, the different strategies by which unacceptable samples are managed, processed and test results reported worldwide. Management of unacceptable specimens warrants therefore immediate harmonization. Alongside the challenging and long road of patient safety, preanalytical phase offers room for improvement, and Editors at Biochemia Medica Journal definitely hope to continue providing a respective mean for reporting studies on different preanalytical phase topics. With pleasure and delight we invite potential future authors to submit their articles examining the quality of various preanalytical activities to Biochemia Medica. We will keep nurturing this topic as our prominent feature and by this we hope to be able to deliver valid evidence for some future guidelines and recommendations. 相似文献
147.
本文探讨了以民用建筑消防实际设计工程中遇到的几个问题,基于对建筑设计防火规范的理解存在着不同理解所致的对建筑设计本身带来一定的设计困难。如建筑体积的算法、底层为商业场所的住宅是否应设置消火栓系统、消防栓的布置、管网上阀门设置等问题进行了分析和讨论。 相似文献
148.
本文对送风口径可调的圆盘形散流器进行了实验研究,该散流器呈倒蘑菇形,设计有不同开口高度对应的三档扇叶位置。本文分别对各出风位置进行不同风量下常温射流特性实验和压力特性实验,比较了不同高径比和净面积比下散流器的最大中心速度、射程、全压损失的变化情况。实验结果表明:开口高度设在最小的档位时向下射流,最大中心速度下降快,全压损失大,风量对扩散半径影响很小。随着开口高度增大,风口变为水平送风,射流最大中心速度随开度的增大下降减慢,全压损失减小,到达一定开口高度后,射程几乎不受风量的变化影响。该圆盘形散流器可在高大空间中满足输送冷、暖风所需的不同送风方式。 相似文献
149.
Jian-cang Zhou Qiu-ping Xu Kong-han Pan Chen Mao Chong-wu Jin 《Journal of Zhejiang University. Science. B》2010,11(5):378-385
Increased intra-abdominal pressure(IAP) is common in intensive care patients,affecting aerated lung volume distribution.The current study deals with the effect of increased IAP and decompressive laparotomy on aerated lung volume distribution.The serial whole-lung computed tomography scans of 16 patients with increased IAP were retrospectively analyzed between July 2006 and July 2008 and compared to controls.The IAP increased from(12.1±2.3) mmHg on admission to(25.2±3.6) mmHg(P<0.01) before decompressive lap... 相似文献
150.
利用引力模型对上海世博会客流量进行定性分析,并对上海世博会客流量进行预测.结果表明,利用引力模型对上海世博会客流量的预测与以前常用的渗透率模型和多元回归模型相比有其自身的优越性,考虑因素更为全面. 相似文献