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   1331篇
  免费   0篇
化学工业   29篇
金属工艺   1篇
机械仪表   1篇
矿业工程   1篇
能源动力   1篇
轻工业   14篇
水利工程   2篇
无线电   5篇
一般工业技术   9篇
冶金工业   1257篇
自动化技术   11篇
  2023年   1篇
  2021年   1篇
  2017年   1篇
  2014年   1篇
  2013年   2篇
  2012年   2篇
  2010年   2篇
  2009年   1篇
  2008年   4篇
  2007年   2篇
  2006年   3篇
  2005年   3篇
  2004年   1篇
  2003年   4篇
  2002年   5篇
  2001年   3篇
  2000年   1篇
  1999年   28篇
  1998年   385篇
  1997年   232篇
  1996年   119篇
  1995年   83篇
  1994年   62篇
  1993年   76篇
  1992年   14篇
  1991年   9篇
  1990年   16篇
  1989年   19篇
  1988年   8篇
  1987年   7篇
  1986年   17篇
  1985年   14篇
  1984年   5篇
  1983年   5篇
  1982年   9篇
  1981年   7篇
  1980年   16篇
  1979年   1篇
  1978年   1篇
  1977年   31篇
  1976年   118篇
  1975年   3篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1970年   1篇
  1969年   2篇
  1968年   1篇
  1955年   2篇
排序方式: 共有1331条查询结果,搜索用时 15 毫秒
21.
Dairy calves and their dams from the dairy herd of the institute were used for this investigation. Calvings were watch carefully and jugular venous blood samples taken immediately after delivery from the cow and the calf and in the calf at 24 hours and at 48 hours of postnatal age as well were analyzed for T4, FT4, T3 and FT3 by luminescence enzyme immunoassay (LEIA). Higher thyroid values in calves than in their dams could be found increasing short after birth and reaching their highest level within 24 hours of postnatal life. The individual thyroid hormone values at birth and at 24 hours and at 48 hours of age are well correlated meaning the changes during the first days are specific for each calf. Strong correlation between the thyroid hormone values of the cows and those of the calves could be found. Mean values of thyroid hormones were significantly higher in female than in male calves all time but not different in the dams of these calves.  相似文献   
22.
23.
24.
DNA preparations from three different groups of serum samples were examined for HBV-DNA via a nested polymerase chain reaction assay (lower detection limit: 10 viral genomes in 100 microliters serum): Group I consisted of 11 uninfected control sera, group II consisted of sera obtained from 11 HBV infected patients and group III consisted of 21 isolated anti-HBc positive samples. The 21 samples from group III were HBV-DNA negative according to a conventional non-nested PCR assay and hybridization with a 32P-labelled probe. Using nested PCR and mass spectrometry, HBV-DNA was detected in none of group I and in all of group II samples. In 11 out of 21 (52%) of the isolated anti-HBc positive sera from group III, HBV-DNA was detected. No correlation was observed between HBV-DNA positivity and anti-HBc titers. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry provided a fast, sensitive and non-radioactive assay for the detection of PCR products without the need for gel electrophoresis or hybridization with labelled probes.  相似文献   
25.
26.
27.
In a pilot study to establish fetal nucleated red blood cell (NRBC) detection in maternal blood, trisomy 13 was diagnosed by FISH analysis at 11 weeks' gestation. The NRBCs were detected after a single-step ficoll density gradient enrichment. In blood samples taken both before and after CVS, 52 and 80 NRBCs, respectively, were found to be positive for fetal haemoglobin. In 47 per cent of these cells, FISH analysis for X and Y chromosomes confirmed the fetal sex. Moreover, 48 per cent of these NRBCs showed three fluorescent signals for a chromosome 13 probe, which confirmed the diagnosis of trisomy 13, previously detected at CVS karyotyping. This is the first report of non-invasive prenatal diagnosis of trisomy 13, i.e., pre-CVS, in the first trimester. The high number of fetal NRBCs detected indicates a connection with aneuploidy, probably due to early impairment of the feto-maternal barrier.  相似文献   
28.
29.
"Interventional ultrasound," defined as any diagnostic and therapeutic procedure performed under ultrasound guidance was first introduced in Europe, where its early development took place in Vienna, in Copenhagen, in Italy and in Switzerland. However, many of the applications of interventional ultrasound have been based on important pioneer work using other less-suitable needle guiding methods from the pre-ultrasound era. The European contributions to "interventional ultrasound" have especially been in the development of new puncture equipment, in the dissemination of various biopsy techniques, and draining procedures and, more recently, in the development of many different tissue-ablation techniques. The above contributions, which are outlined in this historical review, have, together with significant contributions from the rest of the world-not least from the United States and Japan-created a most efficient diagnostic as well as therapeutic tool for the benefit of our patients.  相似文献   
30.
Mutations in a gene encoding a multitransmembrane protein, termed presenilin 1 (PS1), are causative in the majority of early-onset cases of AD. To determine the topology of PS1, we utilized two strategies: first, we tested whether putative transmembranes are sufficient to export a protease-sensitive substrate across a lipid bilayer; and second, we examined the binding of antibodies to specific PS1 epitopes in cultured cells selectively permeabilized with the pore-forming toxin, streptolysin-O. We document that the "loop," N-terminal, and C-terminal domains of PS1 are oriented toward the cytoplasm.  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