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   7793篇
  免费   817篇
  国内免费   476篇
耳鼻咽喉   31篇
儿科学   36篇
妇产科学   73篇
基础医学   1096篇
口腔科学   80篇
临床医学   1066篇
内科学   1435篇
皮肤病学   60篇
神经病学   427篇
特种医学   277篇
外国民族医学   15篇
外科学   848篇
综合类   924篇
现状与发展   4篇
预防医学   452篇
眼科学   66篇
药学   807篇
  35篇
中国医学   585篇
肿瘤学   769篇
  2024年   18篇
  2023年   155篇
  2022年   313篇
  2021年   633篇
  2020年   482篇
  2019年   423篇
  2018年   418篇
  2017年   360篇
  2016年   391篇
  2015年   568篇
  2014年   658篇
  2013年   624篇
  2012年   760篇
  2011年   786篇
  2010年   506篇
  2009年   405篇
  2008年   385篇
  2007年   349篇
  2006年   306篇
  2005年   326篇
  2004年   64篇
  2003年   58篇
  2002年   25篇
  2001年   17篇
  2000年   14篇
  1999年   9篇
  1998年   6篇
  1997年   5篇
  1996年   3篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1988年   1篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1964年   1篇
排序方式: 共有9086条查询结果,搜索用时 656 毫秒
101.
Background: The spatial orientation rules of the important skull base structures are essential for performing endoscopic surgery. However, there is no satisfactory three-dimensional (3-D) anatomy study available to the surgeon at present. The aims of this study are to construct a new method to learn the spatial orientation of anatomical features under endoscopy and to help the surgeon establish a 3-D image of skull base structures in his mind. Methods: A modified MicronTracker navigation system was used to measure the pitch angle, direction angle and distance from the reference points to various anatomical landmarks of the pterygopalatine fossa and related structures (PPFRS) at the skull base in 10 fresh cadavers (20 sides). Results: The location data of the positions of the major landmarks were acquired and a digital model of the anatomical structures of the PPFRS was built, which can be moved, whirled or demonstrated easily. Conclusion: It is practical to measure the positions of the anatomical structures of the PPFRS with a modified binocular vision-based MicronTracker navigation system. It is a valuable exploration tool to help the surgeon establish the orientation of surgical landmarks in his mind by the 3-D parameters and model.  相似文献   
102.
103.
Abstract

Background: Investigation of allele and genotype frequencies of microsatellite loci in various populations is an essential pre-requisite in forensic application.

Aim: The present study obtained population genetic data and forensic parameters of 39 autosomal Short Tandem Repeats (STRs) loci from a Chinese Li ethnic group and estimated the genetic relationships between Li and other reference populations.

Subjects and methods: Thirty-nine STR loci, which include D19S433, D5S818, D21S11, D18S51, D6S1043, D3S1358, D13S317, D7S820, D16S539, CSF1PO, Penta D, D2S441, vWA, D8S1179, TPOX, Penta E, TH01, D12S391, D2S1338, FGA, D6S477, D18S535, D19S253, D15S659, D11S2368, D20S470, D1S1656, D22-GATA198B05, D8S1132, D4S2366, D21S1270, D13S325, D9S925, D3S3045, D14S608, D10S1435, D7S3048, D17S1290 and D5S2500, were amplified in two multiplex DNA-STR fluorescence detection systems for 189 unrelated healthy individuals of the Chinese Li ethnic group. The allele frequency distribution and several parameters commonly used in forensic science were statistically analysed.

Results: A total of 378 alleles were observed with corresponding allelic frequencies ranging from 0.0026–0.5899. The power of discrimination and power of exclusion ranged from 0.7569–0.9672 and 0.2513–0.7355, respectively. The power of exclusion (PE) ranged from 0.2580–0.7943 for trio paternity cases and 0.1693–0.5940 for duo paternity cases. The polymorphism information content (PIC) ranged from 0.5001–0.8611. The cumulative match probability across these 39 loci was 2.4242?×?10?38.

Conclusion: The results indicate that 39 STR loci are polymorphic among the Li ethnic group in Hainan Island in the South China Sea. This set of polymorphic STR loci provide highly polymorphic information and forensic efficiency for forensic individual identification and paternity testing, as well as basic population data for population genetics and anthropological research.  相似文献   
104.
Intestinal tuberculosis (ITB) and Crohn''s disease (CD) are granulomatous disorders with similar clinical manifestations and pathological features that are often difficult to differentiate. This study evaluated the value of fluorescent quantitative polymerase chain reaction (FQ-PCR) for Mycobacterium tuberculosis (MTB) in fecal samples and biopsy specimens to differentiate ITB from CD. From June 2010 to March 2013, 86 consecutive patients (38 females and 48 males, median age 31.3 years) with provisional diagnoses of ITB and CD were recruited for the study. The patients'' clinical, endoscopic, and histological features were monitored until the final definite diagnoses were made. DNA was extracted from 250 mg fecal samples and biopsy tissues from each patient. The extracted DNA was amplified using FQ-PCR for the specific MTB sequence. A total of 29 ITB cases and 36 CD cases were included in the analysis. Perianal disease and longitudinal ulcers were significantly more common in the CD patients (P<0.05), whereas night sweats, ascites, and circumferential ulcers were significantly more common in the ITB patients (P<0.05). Fecal FQ-PCR for MTB was positive in 24 (82.8%) ITB patients and 3 (8.3%) CD patients. Tissue PCR was positive for MTB in 16 (55.2%) ITB patients and 2 (5.6%) CD patients. Compared with tissue FQ-PCR, fecal FQ-PCR was more sensitive (X2=5.16, P=0.02). We conclude that FQ-PCR for MTB on fecal and tissue samples is a valuable assay for differentiating ITB from CD, and fecal FQ-PCR has greater sensitivity for ITB than tissue FQ-PCR.  相似文献   
105.
106.
107.
108.
109.
110.
目的 了解县城乡镇初中生幸福感水平及其影响因素.方法 采用Rosenberg自尊问卷、一般自我效能感量表和中学生应对方式问卷等对706名初中生进行调查.结果 觉得“很幸福”或“幸福”的学生占70.4%;女生的幸福感水平显著高于男生(x2=9.714,P<0.01);家庭经济状况较好的学生,幸福感水平较高(x2=58.184,P<0.001);幸福感水平年级间无显著差异(x2=0.471,P>0.05);自尊、自我效能感、问题解决、寻求社会支持、积极的合理化解释得分幸福组显著高于非幸福组(t1=9.257,t2=3.988,t3=4.245,t4=4.150,t5=5.184,P5<0.001).忍耐、“幻想、否认”、逃避得分幸福组显著低于非幸福组(t1=-3.090,t2=-3.073,Ps<0.01;t3=-3.830,P<0.001).家庭经济状况、自尊、寻求社会支持、逃避应对方式能显著预测县城乡镇初中生的幸福感(x2=136.165,P<0.001).结论 县城乡镇初中生总体上是幸福的,性别、家庭经济状况、自尊、自我效能感和应对方式等因素会影响其幸福感水平,并且家庭经济状况、自尊、寻求社会支持及逃避应对方式能有效预测其幸福感水平.  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