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   2134篇
  免费   1篇
电工技术   1篇
化学工业   10篇
机械仪表   1篇
建筑科学   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
一般工业技术   4篇
冶金工业   2096篇
自动化技术   4篇
  2020年   1篇
  2018年   1篇
  2013年   3篇
  2012年   2篇
  2011年   2篇
  2008年   3篇
  2007年   1篇
  2006年   1篇
  2005年   2篇
  2004年   1篇
  2003年   4篇
  2002年   3篇
  2001年   1篇
  1999年   57篇
  1998年   579篇
  1997年   364篇
  1996年   240篇
  1995年   137篇
  1994年   101篇
  1993年   137篇
  1992年   20篇
  1991年   32篇
  1990年   30篇
  1989年   31篇
  1988年   25篇
  1987年   23篇
  1986年   22篇
  1985年   25篇
  1983年   5篇
  1982年   7篇
  1981年   16篇
  1980年   20篇
  1979年   2篇
  1978年   4篇
  1977年   74篇
  1976年   151篇
  1975年   4篇
  1971年   1篇
  1965年   1篇
  1955年   2篇
排序方式: 共有2135条查询结果,搜索用时 0 毫秒
91.
Occasionally, a major change in vaccine methodology comes along. Such would appear to be the case with the advent of DNA-mediated immunization, colloquially known as DNA vaccines. This represents a radical new way to deliver antigens; it involves the direct introduction of a plasmid DNA encoding an antigenic protein which is then expressed within cells of the organism. This leads to surprisingly strong immune responses, involving both the humoral and cellular arms of the immune system. DNA-mediated immunization to a single antigen can provide protection against infection by a pathogen. Here, a guide is provided comprising twelve steps to help design and carry out DNA-mediated immunization. This approach to immunization will greatly facilitate studies of immunophysiological responses to antigens of pathogenic organisms. An Internet site (URL: http:@www.genweb.com/Dnavax/dnav ax.html) has been created to help promote this potentially revolutionary approach to vaccination in the service of public health.  相似文献   
92.
93.
94.
The current adjustment of cochlear implant (CI) speech processors is based on a knowledge of the lower and upper limits (T- and C-levels) for electrical stimulus currents. These data are usually acquired from subjective classifications of individual patients. In cases with non-reliable patient responses, objective methods are necessary. Especially for the estimation of correct T-levels, auditory evoked potentials (AEP) can be applied, since they allow the determination of response thresholds in a frequency-specific manner. By determining the AEP of different latencies, late cortical responses can be registered almost without artifact contamination. These patients have been examined in 20 patients provided with 22- or 8-channel CI-systems (Nucleus or Med-EI implants). In all cases, clear responses and clearly discernible threshold transitions could be detected. By making use of acoustical stimulation in a free sound field, subjective hearing threshold and the T-levels of electrical stimulation could be verified. Since late responses are generated in the primary auditory cortex, their assessment permits a nearly integral functional control of the aided hearing system. To date, no problems have occurred from maturation or attentional effects in either pediatric or adult patients. The applicability in very young children remains to be explored.  相似文献   
95.
The performance characteristics of the Tandem-MP Ostase assay, a new microplate immunoassay for bone-specific alkaline phosphatase (bone ALP; EC 3.1.3.1) in human sera, are described. Bone ALP is bound to streptavidin-coated microwells by a single biotinylated anti-bone ALP monoclonal antibody. Antigen is detected by the addition of p-nitrophenyl phosphate. The assay is performed at room temperature in <90 min. Imprecision was 2.3-6.1% with a detection limit of 0.6 microg/L. Method comparison of bone ALP measurements with the Tandem-MP Ostase assay and the mass-based Tandem-R Ostase assay (n = 285) indicated regression statistics of Tandem-MP Ostase = 1.03 Tandem-R Ostase + 0.22 microg/L, S(y/x) = 4.0 microg/L, r = 0.97. Serum bone ALP values in apparently healthy men and in pre- and postmenopausal women were also similar between the two Ostase assay formats. Liver ALP reactivity determined using the slope and heat inactivation methods was similar in both Ostase assays. Liver ALP reactivity ranged from 3 microg/L (heat inactivation) to 6 microg/L (slope method) per 100 U/L of liver ALP activity, whereas bone ALP reactivity was 37 microg/L per 100 U/L of bone ALP activity, indicating a liver ALP relative reactivity of 8.1-16.2%. Similar results were obtained with the Alkphase-B bone ALP immunoassay. The Tandem-MP Ostase bone ALP assay demonstrated increased concentrations of serum bone ALP in conditions where bone metabolism is increased and showed a rapid, temporal decrease in serum bone ALP in Paget disease patients on bisphosphonate therapy. In conclusion, the Tandem-MP Ostase assay for serum bone ALP is a rapid, simple, robust nonisotopic alternative to the Tandem-R Ostase immunoradiometric assay that provides an accurate and sensitive assessment of bone turnover.  相似文献   
96.
97.
98.
99.
100.
Noradrenaline was administered through the stomach or peritoneum in thirty patients of the Raza Hospital of the I.M.S.S. in an attempt to control severe gastro-intestinal bleeding as described by Dr. H. H. Le Veen. In 84% of the cases this was accomplished with an average elapsed time of 82 minutes. The method proved to be effective of various etiologies except in those cases in which an important size artery was involved. There were no side effects.  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