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   408篇
  免费   33篇
  国内免费   11篇
耳鼻咽喉   1篇
儿科学   15篇
妇产科学   11篇
基础医学   61篇
口腔科学   5篇
临床医学   36篇
内科学   74篇
皮肤病学   5篇
神经病学   14篇
特种医学   161篇
外科学   11篇
综合类   5篇
预防医学   6篇
眼科学   6篇
药学   15篇
肿瘤学   26篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2019年   1篇
  2018年   7篇
  2017年   1篇
  2016年   5篇
  2015年   3篇
  2014年   3篇
  2013年   8篇
  2012年   17篇
  2011年   8篇
  2010年   12篇
  2009年   13篇
  2008年   13篇
  2007年   19篇
  2006年   10篇
  2005年   12篇
  2004年   14篇
  2003年   12篇
  2002年   11篇
  2001年   17篇
  2000年   7篇
  1999年   7篇
  1998年   16篇
  1997年   22篇
  1996年   21篇
  1995年   21篇
  1994年   18篇
  1993年   15篇
  1991年   3篇
  1990年   3篇
  1989年   11篇
  1988年   13篇
  1987年   14篇
  1986年   18篇
  1985年   23篇
  1984年   8篇
  1983年   13篇
  1982年   10篇
  1981年   2篇
  1980年   3篇
  1978年   2篇
  1977年   4篇
  1976年   5篇
  1975年   2篇
  1966年   1篇
  1963年   1篇
排序方式: 共有452条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
7.
The complete nucleotide (nt.) sequence of the RNA polymerase (3D) gene and 81 nt. in the 3-untranslated region of foot-and-mouth disease virus (FMDV) serotype Asia1 (IND63/72) was determined and compared with the sequence of other FMDV serotypes. The 3D genomic region was 1410 nt. long encoding 470 amino acids with an inframe stop codon (TAA) at nt. position 1411–1413. The deduced amino acid sequence of the protein showed 8 conserved motifs as reported in other picornaviruses, 2 of which are 100% identical across the serotypes. Antigenic regions in the polymerase protein were predicted and found to be located at the N-terminus of the protein. The phylogenetic analysis showed that the FMD viruses were segregated into different clusters based on geographical origin; the Asia1 virus did not cluster tightly with any of the geographical groups.  相似文献   
8.
9.
To determine whether ultrasonographic findings can predict the karyotype of spontaneous abortions, 137 pregnancies (54 spontaneous, 83 assisted ovulatory cycles) that subsequently aborted and had chromosome analysis performed on the products of conception were studied ultrasonographically. Transvaginal ultrasound was performed using an Acuson 128XP/10 with 7.5 MHz probe. The numbers of empty gestational sacs, small and normal for gestational size, embryonic poles and embryos with documented cardiac activity were calculated. The frequency of each of these findings in pregnancies with normal and abnormal karyotypes was compared. Of the 137 spontaneous abortions, 51 had normal chromosome analyses and 86 had abnormal karyotypes (68 aneuploidies and 18 polyploidies). Ultrasonographic findings in the 51 karyotypically normal pregnancies included 16 (31%) with empty gestational sacs, and 35 (69%) with embryonic poles, of which 24 (69%) were at least 1 week smaller than expected for gestational age and 11 (31%) were the expected size. Embryonic cardiac activity was documented in 22 (63%) of the 35 embryonic poles. Amongst 86 pregnancies with abnormal karyotypes, similar frequencies of ultrasound findings were found: 23 (27%) with empty gestational sacs, 42 (67%) with embryonic poles smaller than expected for gestational age, and 50 (79%) embryos lost after documentation of embryonic cardiac activity. No differences in the frequency of ultrasonographic findings of empty gestational sacs, small embryonic pole and embryonic cardiac activity were observed between karyotypically normal and abnormal spontaneous abortions. Ultrasonographic findings cannot predict the karyotype of spontaneous abortions.   相似文献   
10.
Poor prognosis in nasopharyngeal carcinoma patients may result from resistance to the apoptosis-inducing effect of radio- and/or chemotherapy. Apoptosis depends on proper activation of caspase 3, resulting in cleavage of key proteins like PARP-1. To investigate whether disruption of the apoptosis pathway results in therapy-resistant tumour cells, we investigated whether absence of caspase 3 activation in tumour biopsies of nasopharyngeal carcinoma patients is related to poor clinical outcome. Moreover, we investigated whether absence of caspase 3 activation is related to loss of procaspase 3 expression or expression of the apoptosis regulators p53, bcl-2 and XIAP. We studied 36 Indonesian nasopharyngeal carcinoma patients without evidence of distant metastases who were treated with curative intent by radiotherapy only. Activation of caspase 3 and expression of the different markers were determined using specific antibodies. Levels of caspase 3 activation were determined by quantifying positively staining tumour cells. Nasopharyngeal carcinoma-derived C15 and C17 tumour cells were used as control. Absence of caspase 3 activation was strongly related to a poor clinical response to radiotherapy and to a higher T and N stage, resulting in a particularly poor clinical outcome with regard to progression-free (P<0.0001) and overall survival time (P<0.0001). Absence of caspase 3 activation was significantly correlated to loss of expression of procaspase 3 (P=0.04). In nasopharyngeal carcinoma patients treated with curative intent, absence of active caspase 3-positive neoplastic cells predicts rapid fatal outcome, and is associated with poor response to radiotherapy and high T and N stage at time of presentation.  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