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   12727篇
  免费   29篇
  国内免费   1篇
教育   9823篇
科学研究   1295篇
各国文化   18篇
体育   427篇
文化理论   394篇
信息传播   800篇
  2022年   9篇
  2021年   14篇
  2020年   30篇
  2019年   48篇
  2018年   2212篇
  2017年   2130篇
  2016年   1594篇
  2015年   135篇
  2014年   149篇
  2013年   381篇
  2012年   243篇
  2011年   716篇
  2010年   860篇
  2009年   455篇
  2008年   668篇
  2007年   1166篇
  2006年   83篇
  2005年   411篇
  2004年   464篇
  2003年   372篇
  2002年   141篇
  2001年   17篇
  2000年   36篇
  1999年   14篇
  1998年   18篇
  1997年   23篇
  1996年   10篇
  1995年   8篇
  1994年   10篇
  1993年   16篇
  1992年   10篇
  1991年   22篇
  1990年   13篇
  1989年   9篇
  1988年   14篇
  1986年   9篇
  1985年   7篇
  1984年   7篇
  1983年   7篇
  1982年   11篇
  1981年   8篇
  1980年   8篇
  1979年   11篇
  1978年   16篇
  1977年   11篇
  1976年   11篇
  1973年   8篇
  1970年   7篇
  1964年   6篇
  1960年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
To analyse the association of high sensitivity C-reactive (hsCRP) protein levels and −717A/G single nucleotide polymorphism of CRP with acute myocardial infarction (AMI) in the Indian population. Study population included 100 MI cases wherein 32 patients had experienced previous MI (MI-Group-1), 68 MI cases were recruited at presentation (MI-Group-2) and equal number of age and gender matched healthy individuals. hsCRP levels were determined by ELISA and genotyping of −717A/G was carried out by polymerase chain reaction-based restriction digestion method. The −717A/G genotypes did not influence hsCRP level and their distribution did not differ between groups. However, in the present study hsCRP demonstrated significant correlation with BMI in controls of both the genders and with triglycerides in females of AMI at presentation who otherwise are with low risk profile. Identifying traditional risk factors associated with inflammation may help in controlling the acute event.  相似文献   
973.
Breast cancer is one of the most frequent malignancies in the world. Available staging procedures to detect breast cancer are bone scan, chest X-ray, liver ultrasonography, computerized tomography, estimation of tumor markers like carbohydrate antigen (CA15-3) and carcino embryonic antigen. These procedures are expensive and may not be required in all cases. Out of 70 patients studied, 55 had normal CA15-3 and 15 had elevated levels of Ca15-3. Eight (14.5%) of the 55 patients with normal CA15-3 had abnormal bone scan. Fifteen patients had CA15-3 levels above the normal range and among these 9 (60%) had abnormal bone scan. While prime facie it would appear that a high level of CA15-3 correlate with abnormal bone scan, it is also true that the numbers are small at present and conclusions about the validity of CA15-3 as marker of bone metastasis may be premature.  相似文献   
974.
975.
##正##Dr.Gruntzig et al.(1979) successfully completed the world's first percutaneous coronary intervention (PCI),a percutaneous transluminal coronary  相似文献   
976.
The aim of this study is to build two mathematical models of canine ionic currents specific to right atria and left atria.The canine left atria mathematical model was firstly modified from the Ramirez-Nattel-Courtemanche(RNC) model using the recently available experimental data of ionic currents and was further developed based on our own experimental data.A model of right atria was then built by considering the differences between right atria and left atria.The two developed models well reproduced the exper...  相似文献   
977.
Neurochip based on light-addressable potentiometric sensor(LAPS),whose sensing elements are excitable cells,can monitor electrophysiological properties of cultured neuron networks with cellular signals well analyzed.Here we report a kind of neurochip with rat pheochromocytoma(PC12) cells hybrid with LAPS and a method of de-noising signals based on wavelet transform.Cells were cultured on LAPS for several days to form networks,and we then used LAPS system to detect the extracellular potentials with signals d...  相似文献   
978.
Congenital atresia of the left main coronary artery is a rare occurrence, and surgical revascularizationbypass graft is required. We here report a rare case of congenital coronary anomaly in an infant. A 10-month-old male infant was admitted to the hospital with heart failure symptoms. Echocardiographic examinations revealed mitral valve regurgitation and ischemic changes of the anterolateral papillary muscle and chordae. Coronary angiography showed atresia of the left main coronary artery with a severe hypoplastic left anterior descending artery and a circumflex coronary artery. Unfortunately, sudden cardiac arrest occurred after catheterization and the infant did not recover despite of immediate cardiopulmonary resuscitation. Further studies are needed to find a newer diagnostic method to detect coronary anomaly in an infant, and coronary angiography, if necessary, has to be performed very carefully.  相似文献   
979.
This paper reports on the electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter. The coupling coils and human tissues, including the skin, fat, muscle, liver, and blood, were considered. Specific absorption rate (SAR) and current density were analyzed by a finite-length solenoid model. First, SAR and current density as a function of frequency (10–107 Hz) for an emission current of 1.5 A were calculated under different tissue thickness. Then relations between SAR, current density, and five types of tissues under each frequency were deduced. As a result, both the SAR and current density were below the basic restrictions of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The results show that the analysis of these data is very important for developing the artificial anal sphincter system.  相似文献   
980.
This paper seeks to examine the quality and equality of basic education of Hong Kong based on the first three cycles of the Program for International Student Assessment (PISA). Results from these three assessments suggested that the Hong Kong students have an outstanding performance in mathematics, science and reading. In particular, the performance of reading improves substantially in PISA 2006. As far as equality in education is concerned, the achievement gap of students from different socio-economic backgrounds in Hong Kong is relatively small compared with other countries. However, the academic performance variation between-schools suggest that, there is still academic segregation among secondary schools in Hong Kong although it has been reduced slightly in the PISA 2006.  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