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   928篇
  免费   7篇
电工技术   3篇
综合类   1篇
化学工业   50篇
金属工艺   14篇
机械仪表   14篇
建筑科学   11篇
矿业工程   2篇
能源动力   10篇
轻工业   20篇
石油天然气   8篇
无线电   41篇
一般工业技术   49篇
冶金工业   692篇
原子能技术   4篇
自动化技术   16篇
  2021年   4篇
  2020年   8篇
  2019年   5篇
  2018年   5篇
  2017年   4篇
  2016年   9篇
  2015年   5篇
  2014年   11篇
  2013年   22篇
  2012年   6篇
  2011年   10篇
  2010年   22篇
  2009年   6篇
  2008年   13篇
  2007年   13篇
  2006年   6篇
  2005年   6篇
  2004年   7篇
  2002年   3篇
  2000年   4篇
  1999年   31篇
  1998年   186篇
  1997年   124篇
  1996年   83篇
  1995年   66篇
  1994年   37篇
  1993年   46篇
  1992年   9篇
  1991年   8篇
  1990年   4篇
  1989年   10篇
  1988年   16篇
  1987年   7篇
  1986年   5篇
  1985年   13篇
  1984年   2篇
  1982年   2篇
  1980年   12篇
  1979年   3篇
  1978年   2篇
  1977年   18篇
  1976年   38篇
  1973年   5篇
  1971年   3篇
  1970年   2篇
  1969年   2篇
  1968年   3篇
  1957年   2篇
  1956年   3篇
  1955年   3篇
排序方式: 共有935条查询结果,搜索用时 15 毫秒
51.
J Mack 《Canadian Metallurgical Quarterly》1997,278(8):632; author reply 632-632; author reply 633
  相似文献   
52.
53.
In the last decade a good number of biotechnical methods have been developed. They are available in medical, biological, and ecological fields of work as well as techniques that can replace animal experiments. These methods have been developed on the basis of researchwork in andrology (AI and cryoconservation of spermatozoa), endocrinology (hormonal control of reproduction) and the availability of industrial produced hormones and their analog. On the other hand practical clinical techniques for examination like the availability of sonography advice and clinical practical techniques for non-surgical recovery and transplantation of gamets and embryos have been the prerequisites for a successful work in this field of action. These fields of action are extended from breeding aspects (genetical progress) over the control of epidemics to the exportation of genetic material (especially developing countries to overcome hygienic and adaptation problems), the creation of gen-pools (conservation of breeds-species) and as well as the elimination of genetic defects like BLAD or DUMPS by help of PCR-techniques or the identification of positive characters like milk components and sexing of embryos. The industrial use of bioproducts produced by especially designed biosystems is in work but in Germany not possible by reasons of legislative restrictions. In the light of these developments the veterinary fields of work should be discussed and focussed towards an understanding that the veterinarian should be active and in a polposition in the processing of reproduction and production and presentation of food of animal origin by using these new technologies.  相似文献   
54.
A new presidential administration provides an opportunity to change the course of government in Washington.  相似文献   
55.
In the world of air regulations, the year 2016 will be remembered not for any major action by the Environmental Protection Agency (EPA) in developing, revising, or defending its rules, but for the result of the November 8 presidential election that took most of the United States, if not the world, by surprise. Donald Trump's election and the transition to a Republican administration will undoubtedly be the primary influence (and major question mark) in the air quality regulation landscape in 2017. As Trump prepares to take office, speculation is rampant about whether the promises he made on the campaign trail will translate into action. Chief among those promises was a vow to eliminate or roll back efforts aimed at regulating climate change, including the repeal of the EPA's Clean Power Plan (CPP) and withdrawal from the Paris climate change accord.  相似文献   
56.
57.
The effect of the testosterone derivative oxymetholone alone or in combination with the H1-receptor antagonist ketotifen, which has recently been shown to block tumour necrosis factor alpha (TNF alpha), on weight gain and performance status in human immunodeficiency virus (HIV) patients with chronic cachexia was evaluated in a 30-week prospective pilot study. Thirty patients were randomly assigned to either oxymetholone monotherapy (n 14) or oxymetholone plus ketotifen (n 16). Patients receiving treatment were compared with a group of thirty untreated matched controls, who met the same inclusion criteria. Body weight and the Karnofsky index, which assesses the ability to perform activities of daily life, and several quality-of-life variables were measured to evaluate response to therapy. The average weight gain at peak was 8.2 (SD 6.2) kg (+ 14.5% of body weight at study entry) in the oxymetholone group (P < 0.001), and 6.1 (SD 4.6) kg (+10.9%) in the combination group (P < 0.005), compared with an average weight loss of 1.8 (SD 0.7) kg in the untreated controls. The mean time to peak weight was 19.6 weeks in the monotherapy group and 20.8 weeks in the combination group. The Karnofsky index improved equally in both groups from 56% before to 67% after 20 weeks of treatment (P < 0.05). The quality of life variables (activities of daily life, and appetite/nutrition) improved in 68% (P < 0.05) and 91% (P < 0.01) of the treated patients respectively. Oxymetholone was safe and promoted weight gain in cachectic patients with advanced HIV-1 infection. The addition of ketotifen did not further support weight gain. These results suggest the need for a randomized, double-blind, placebo-controlled multicentre trial.  相似文献   
58.
59.
Tetanus has become an uncommon disease in developed countries. Tetanus is caused by exotoxins from the bacteria Clostridium tetani. This microbe, which is obligate anaerobe, is present in soil, and animal and human faeces. The condition usually appears after contamination of wounds. However, reports have been published of tetanus occurring after both acute and selective gastrointestinal surgery. We present a case of severe postoperative tetanus in a 57 year-old woman who underwent bowel resection after strangulation of the ileum. The patient was treated on an intensive care unit and was artificially ventilated for 64 days. Seven months later she had fully recovered. Clinical presentation, diagnosis, treatment, and complications are discussed in the report. The diagnosis of tetanus is made by clinical observation. Nowadays, lack of suspicion of this condition may cause delay in administering proper treatment. Women and older men are often inadequately immunized. Doctors should therefore examine the immunization status of these groups of patients regularly.  相似文献   
60.
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