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   817篇
  免费   8篇
  国内免费   8篇
电工技术   15篇
综合类   1篇
化学工业   137篇
金属工艺   13篇
机械仪表   20篇
建筑科学   57篇
矿业工程   2篇
能源动力   14篇
轻工业   100篇
水利工程   6篇
石油天然气   2篇
无线电   50篇
一般工业技术   91篇
冶金工业   267篇
原子能技术   13篇
自动化技术   45篇
  2021年   11篇
  2019年   8篇
  2018年   8篇
  2017年   7篇
  2016年   7篇
  2015年   6篇
  2014年   8篇
  2013年   33篇
  2012年   19篇
  2011年   13篇
  2010年   26篇
  2009年   25篇
  2008年   20篇
  2007年   26篇
  2006年   15篇
  2005年   16篇
  2004年   11篇
  2003年   16篇
  2002年   15篇
  2001年   13篇
  2000年   16篇
  1999年   21篇
  1998年   82篇
  1997年   45篇
  1996年   44篇
  1995年   21篇
  1994年   18篇
  1993年   19篇
  1992年   7篇
  1991年   9篇
  1990年   7篇
  1989年   6篇
  1988年   9篇
  1987年   7篇
  1986年   7篇
  1985年   7篇
  1984年   15篇
  1983年   23篇
  1982年   14篇
  1981年   6篇
  1980年   8篇
  1979年   10篇
  1978年   9篇
  1977年   19篇
  1976年   26篇
  1975年   15篇
  1974年   8篇
  1973年   9篇
  1971年   6篇
  1970年   5篇
排序方式: 共有833条查询结果,搜索用时 218 毫秒
61.
62.
PURPOSE: The relationship between green tea intake and serum concentrations of total cholesterol, triglycerides, and high density lipoprotein cholesterol was examined. METHODS: The subjects were 630 middle-aged men and their 370 wives sampled from five regions of Japan during 1989-1991. Consumption frequency of 38 foods, including green tea, was determined by interview. Three-day food records were collected from 207 of the men and 164 of the wives. The mean serum concentrations of the three lipids were compared according to the three levels of daily green tea intake (< 1 cup, 1-4 cups, and > 4 cups), with adjustments for various health habits, food frequencies, and nutrient intakes. RESULTS: After extensive multivariate adjustments for nondietary and dietary covariates, green tea was not associated with any of the lipid levels. CONCLUSIONS: The results of this cross-sectional study do not support the beneficial effects of green tea on serum lipid levels.  相似文献   
63.
64.
OBJECTIVE: The purpose of this study was to assess the efficacy of fluvoxamine in the treatment of binge-eating disorder. Binge-eating disorder is a newly described eating disorder characterized by recurrent episodes of binge eating but without purging behaviors. Uncontrolled reports have suggested that serotonin selective reuptake inhibitors (SSRIs) may be effective in treating this disorder. METHOD: Eighty-five outpatients with a DSM-IV diagnosis of binge-eating disorder were randomly assigned to receive either fluvoxamine (N=42) or placebo (N=43) in a 9-week, parallel-group, double-blind, flexible dose (50-300 mg) study at three centers. The primary outcome measures were frequency of binge eating, expressed as log ([binges/week]+1), and Clinical Global Impression (CGI) scale ratings. Secondary measures included the level of response (based on the percentage change in frequency of binges), body mass index, and Hamilton Rating Scale for Depression score. Except for the level of response, the outcome measures were analyzed by random regression methods; the treatment-by-time interaction was the measure of treatment effect. RESULTS: Compared with placebo, fluvoxamine was associated with a significantly greater rate of reduction in the frequency of binges, rate of reduction in CGI severity scores, rate of increase in CGI improvement scores, level of response for patients who completed the 9-week study, and rate of reduction in body mass index. There was no significant difference between placebo and fluvoxamine groups in the rate of decrease in Hamilton depression scale scores. A significantly greater proportion of patients receiving fluvoxamine than those receiving placebo discontinued treatment because of an adverse medical event. CONCLUSIONS: In this placebo-controlled trial, fluvoxamine was found to be effective according to most outcome measures in the acute treatment of binge-eating disorder.  相似文献   
65.
66.
Translational recruitment of maternal mRNAs is an essential process in early metazoan development. To identify genes required for this regulatory pathway, we have examined a collection of Drosophila female-sterile mutants for defects in translation of maternal mRNAs. This strategy has revealed that maternal-effect mutations in the cortex and grauzone genes impair translational activation and cytoplasmic polyadenylation of bicoid and Toll mRNAs. Cortex embryos contain a bicoid mRNA indistinguishable in amount, localization, and structure from that in wild-type embryos. However, the bicoid mRNA in cortex embryos contains a shorter than normal polyadenosine (poly(A)) tail. Injection of polyadenylated bicoid mRNA into cortex embryos allows translation demonstrating that insufficient polyadenylation prevents endogenous bicoid mRNA translation. In contrast nanos mRNA, which is activated by a poly(A)-independent mechanism, is translated in cortex embryos, indicating that the block in maternal mRNA activation is specific to a class of mRNAs. Cortex embryos are fertilized, but arrest at the onset of embryogenesis. Characterization of grauzone mutations indicates that the phenotype of these embryos is similar to cortex. These results identify a fundamental pathway that serves a vital role in the initiation of development.  相似文献   
67.
68.
Sharing risk with HMOs requires the patience of a kindergarten teacher, the finesse of a U.N. negotiator, and the agility of a fighter pilot. Intimidated yet? Neither are these executives. Our exclusive data show how hospitals handle risk contracts.  相似文献   
69.
Partitioning of long-lived minor actinides (americium and curium) from the nuclear wastes issuing the reprocessing of nuclear spent fuels, in order to transmute them into short-lived nuclides or to condition them into stable crystalline matrices, was the subject of intense research within the NEWPART research program of the European 4th Frame Work Program, FWP (1996–1999). The target waste considered was the acidic raffinate (HAR) issuing the reprocessing of the used nuclear fuels by the PUREX process. A two step separation process based on liquid-liquid extraction was designed. The first step consists in the co-separation of the mixture of trivalent actinides and lanthanides from the HAR by extraction with a malonamide extractant (DIAMEX process), while the second step concerns the actinides(III)/lanthanides(III) group separation (SANEX process). Several DIAMEX and SANEX processes were developed and successfully tested with cold, spiked and genuine high active effluents. The research carried out also included basic and fundamental works in order to better understand the relationships between the structures of the extractants and their affinities for the target metal ions. The lecture highlighted both the basic and applied aspects of the research. This work will be pursued (PARTNEW program) within the 5th FWP of the European Union during the period 2000–2003.  相似文献   
70.
Twelve naive and nine test-vaccinated horses which developed clinical signs of rabies as a result of the required protocol of a vaccine trial were prospectively observed. Nineteen of the 21 cases were confirmed positive for rabies infection of the brain by fluorescent antibody test. The two horses with negative results had ganglioneuritis of the trigeminal ganglion or lymphocytic perivascular cuffing in the brain stem in addition to clinical signs. Average incubation period was 12.3 days and average morbidity was 5.5 days. Naive animals had significantly shorter incubation and morbidity periods (P < 0.05). Muzzle tremors were the most frequently observed (81%) and most common initial sign. Other common signs were pharyngeal spasm or pharyngeal paresis (71%), ataxia or paresis (71%), lethargy or somnolence (71%). The furious form was manifested in 43% of rabid horses and some of these furious animals initially manifested the dumb form. The paralytic form was not observed. Histopathology was characteristics for rabies. The results of this trial do not reflect on the efficacy of commercially licensed equine rabies vaccines.  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