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   2509篇
  免费   6篇
  国内免费   3篇
电工技术   5篇
综合类   1篇
化学工业   23篇
金属工艺   5篇
机械仪表   5篇
建筑科学   9篇
能源动力   4篇
轻工业   12篇
水利工程   1篇
无线电   7篇
一般工业技术   35篇
冶金工业   2387篇
原子能技术   11篇
自动化技术   13篇
  2021年   2篇
  2019年   2篇
  2017年   4篇
  2016年   2篇
  2015年   4篇
  2014年   1篇
  2013年   8篇
  2012年   5篇
  2011年   5篇
  2010年   8篇
  2009年   5篇
  2008年   2篇
  2007年   5篇
  2006年   5篇
  2005年   2篇
  2004年   9篇
  2003年   6篇
  2002年   2篇
  2001年   5篇
  2000年   3篇
  1999年   85篇
  1998年   745篇
  1997年   459篇
  1996年   280篇
  1995年   161篇
  1994年   117篇
  1993年   165篇
  1992年   23篇
  1991年   21篇
  1990年   26篇
  1989年   18篇
  1988年   17篇
  1987年   19篇
  1986年   26篇
  1985年   16篇
  1984年   1篇
  1983年   4篇
  1982年   13篇
  1981年   15篇
  1980年   24篇
  1979年   4篇
  1978年   6篇
  1977年   55篇
  1976年   121篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1971年   1篇
  1969年   1篇
  1955年   4篇
排序方式: 共有2518条查询结果,搜索用时 15 毫秒
121.
Eradication of multiple nodules, papules, and plaques of pigmented basal cell epitheliomas of the back of one patient was achieved by nine months of daily treatment with 5% fluorouracil cream. Such topical chemotherapy offers the physician an alternative to surgery and radiation in treating patients who have widespread nodular superficial epitheliomas. The need for a prolonged period of treatment and follow-up is emphasized.  相似文献   
122.
1. An improved purification was developed for L-lactate oxidase from Mycobacterium smegmatis. 2. The mol.wt. of the native enzyme by a sedimentation-equilibrium analysis was 345 000, and other ultracentrifuge methods gave values in the range 345 000-350 000. 3. An amino acid analysis, determinations of protein and flavin, a sedimentation-velocity analysis and an approach to equilibrium analysis gave values for the subunit mol.wt. in the range 43 500-47 000. 4. It was concluded that L-lactate oxidase contains eight subunits of mol.wt. 43 500. 5. Cross-linking of the subunits with dimethyl suberimidate and electron-microscopy studies were consistent with an octameric structure.  相似文献   
123.
124.
The free sulfhydryls of brain tubulin prepared by cyclic polymerization procedures both with and without glycerol have been examined. The average free sulfhydryl titer of tubulin prepared with glycerol (7.0 sulfhydryls/55,000 mol wt) is greater than that of tubulin prepared without glycerol (4.0 sulfhydryls/55,000 mol wt). Diamide, a sulfhydryl-oxidizing agent, inhibits the polymerization of tubulin. Diamide also disperses the 20S and 30S oligomers of tubulin seen in analytical ultracentrifuge patterns of tubulin solutions and, depending on the temperature at which diamide is added, converts all or part of the oligomeric material to 6S dimers. Electron microscopy demonstrates that diamide also destroys the 450-A ring structures characteristic of tubulin solutions. All diamide effects are reversible by the addition of 10 mM dithioerythreitol, a sulfhydryl-reducing agent. That diamide interacts with sulfhydryls on tubulin is directly demonstrated by a 50% decrease in the free sulfhydryl titer of tubulin measured after diamide treatment. Concentrations of CaCl2 which inhibit polymerization also decrease the free sulfhydryl titer of tubulin.  相似文献   
125.
126.
127.
Films of linolenic acid supported on chromatographic type silica gel undergo autoxidation at a rate which is slow compared to that in homogeneous phase at low surface coverage but comparable to it at coverages approximating a close-packed monolayer. The new observation reported here is that these surface phase oxidations are chemiluminescent. The quantum yield is ca. 10−12 quanta per molecule of fatty acid reacted for a close-packed monolayer and remains approximately constant with decreasing coverage. The emission intensity is temperature dependent, with an apparent activation energy of 10 kcal mol−1, and shows an induction period for close-packed monolayers. The emission spectrum contains a component consistent with excited state ketone emission and a low energy component, ca. 600+ nm, which could be due to singlet oxygen emission. The existence of the emission means that surface autoxidation reactions can be followed in place; the nature of the emission may provide insight into the autoxidation mechanism beyond that which may be inferred from conventional rate measurements.  相似文献   
128.
129.
On the basis of own observations of courses the author adopts a definite attitude to the early symptomatology of the rheumatoid arthritis. During the first weeks of the rheumatoid arthritis the following symptoms are found: articular syndromes, more frequently in form of obstinate polyarthralgias, mono-oligoarthritis, accompanied by morning rigidity and accelerated BSR as well as impairment of the general condition. In the majority of the patients only the tentative diagnosis rheumatoid arthritis may be made. After a one to three months' course of the disease the diagnosis becomes more probable. It is above all based on constancy and symmetry, characteristic localisation of the articular process, morning rigidity, radiologically paraarticular loosening of the structure and morphological symptoms of an acute and subacute synovialitis. 6 to 12 months after the beginning of the disease a clinical picture forms which allows to make the diagnosis of a certain or classical rheumatoid arthritis in accordance with the criteria of the ARA. The occurrence of a high activity of multiple affection of the joints (permanent symmetrical polyarthritis including the small joints of the hands and feet), distinctive morning rigidity, high fever and much accelerated BSR, beginning with the first weeks of the disease, speaks for the possibility of the development of an arthrovisceral form of the course of rheumatoid arthritis.  相似文献   
130.
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