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   4446篇
  免费   1篇
电工技术   5篇
化学工业   50篇
机械仪表   2篇
建筑科学   3篇
能源动力   24篇
轻工业   17篇
水利工程   7篇
石油天然气   3篇
无线电   16篇
一般工业技术   34篇
冶金工业   4266篇
原子能技术   2篇
自动化技术   18篇
  2023年   1篇
  2021年   1篇
  2019年   3篇
  2018年   4篇
  2017年   1篇
  2016年   3篇
  2015年   1篇
  2014年   4篇
  2013年   7篇
  2012年   10篇
  2011年   5篇
  2010年   4篇
  2009年   5篇
  2008年   9篇
  2007年   16篇
  2006年   18篇
  2005年   7篇
  2004年   3篇
  2003年   13篇
  2002年   15篇
  2001年   2篇
  2000年   3篇
  1999年   141篇
  1998年   1426篇
  1997年   803篇
  1996年   520篇
  1995年   259篇
  1994年   240篇
  1993年   254篇
  1992年   33篇
  1991年   40篇
  1990年   37篇
  1989年   51篇
  1988年   48篇
  1987年   26篇
  1986年   25篇
  1985年   25篇
  1984年   5篇
  1983年   10篇
  1982年   12篇
  1981年   17篇
  1980年   36篇
  1978年   5篇
  1977年   88篇
  1976年   195篇
  1975年   9篇
  1974年   2篇
  1973年   1篇
  1966年   2篇
  1965年   1篇
排序方式: 共有4447条查询结果,搜索用时 15 毫秒
101.
The present study examined the effect of received support on adjustment by foreign students, with data from 33 Chinese students who completed questionnaires at three occasions: three months (the first period), nine months (the second period), and one year and nine months (the third period) after they arrived in Japan. The Social Support Scale for Chinese Students in Japan (Jou, 1993a) and items for measurement of adjustment were used in the questionnaires. Analysis of Variance results revealed no differences among the amounts of support received during the three periods, but compared with the first or second, adjustment was better during the third period. Results from path analysis indicated that support in the first period was positively related to adjustment in the first period, the first period adjustment and second period support positively to the second period adjustment, and only the second period adjustment positively to the third period adjustment. Thus, the present study suggests that it is especially necessary to provide more support to foreign students during the critical early period in order to facilitate their adjustment.  相似文献   
102.
Although self-report data are generally evaluated as reliable, validity estimates for self-reported drinking behavior are not as favorable. A new method of measurement addressing problems currently associated with the questionable validity of self-report drinking information is introduced. Study 1 tests the correspondence between the new measure (occasions per year blood alcohol level exceeded 0.08%), traditional self-report measures, and laboratory alcohol consumption. The novel measure correlated most strongly with volume of alcohol consumed in the laboratory compared to the traditional measures. In Study 2 the novel measure was favored over a traditional measure when discriminating between the presence and absence of problem-drinking symptoms.  相似文献   
103.
Orocaecal transit time (OCTT) was assessed in six healthy beagles by means of the breath hydrogen test (BH2T) and the sulphasalazine/sulphapyridine method (SLZ) after the administration of a test meal of canned food mixed with sulphasalazine. Orocaecal transit time was defined as the time taken from the oral administration of the test meal to the time when the first portion of the meal reached the colon. In five of the dogs the OCTTs assessed by the BH2T were shorter than those measured by the SLZ method by 30, 15, 45, 30 and 45 minutes. However, the median OCTT assessed by the BH2T (135 minutes, range 120 to 195 minutes) was not significantly different from that measured by the SLZ (180 minutes, range 150 to 210 minutes) and was highly correlated with it (r = 0.94, P = 0.016). The sixth dog maintained baseline hydrogen and plasma sulphapyridine readings throughout the monitoring period and the OCTT could not be measured.  相似文献   
104.
105.
The complexity of the spot patterns of two-dimensional electrophoresis gels made it necessary to use image processing techniques to analyze the gels. An important issue in the analysis is the detection and quantification of the protein spots. In this paper we describe a new technique to segment and model the different spots. For the segmentation of a gel into its different spot regions we apply a watershed technique, which is robust and efficient. For the quantification of the spots, a new spot model is constructed, based on diffusion principles. Besides the advantage of having a physical interpretation, the model is demonstrated to be superior to the commonly used Gaussian models.  相似文献   
106.
107.
108.
109.
OBJECTIVE: To characterize the nature of hepatitis G virus (HGV) infections in hemodialysis patients and to determine the responsiveness of HGV to antiviral therapy in these patients. METHODS: HGV, a recently identified flavivirus, is associated with non-A-E viral hepatitis infections. We studied HGV infections in hepatitis C virus (HCV)-infected hemodialysis patients over a 1-yr period, using two independent PCR assays and nucleic acid sequencing. Thirty-four of 63 study patients were treated with interferon. RESULTS: We observed a 27% prevalence (17/63 patients) and a 4% annual incidence of HGV infections in the study population. HGV was not detected in any of the 10 HGV-infected patients immediately after interferon therapy. Although seven of these 10 patients developed HGV relapses, three had long-term responses. The interferon responsiveness of HGV and HCV appeared to be unrelated. In contrast, all seven untreated HGV-infected patients remained viremic. Sequence analyses of the different HGV isolates revealed only very limited genetic variability in the polymerase chain reaction-amplified regions of HGV during 1 yr of observation. CONCLUSIONS: Our data suggest that HCV-infected hemodialysis patients are at substantial risk of acquiring HGV infection and that HGV infections are prevalent in this population. In addition, HGV infections become chronic but are responsive to interferon treatment.  相似文献   
110.
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