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   1932篇
  免费   14篇
  国内免费   2篇
电工技术   2篇
综合类   2篇
化学工业   75篇
金属工艺   8篇
机械仪表   10篇
建筑科学   10篇
矿业工程   1篇
能源动力   30篇
轻工业   44篇
水利工程   1篇
石油天然气   1篇
无线电   30篇
一般工业技术   100篇
冶金工业   1607篇
原子能技术   5篇
自动化技术   22篇
  2023年   9篇
  2022年   4篇
  2021年   11篇
  2020年   8篇
  2019年   4篇
  2018年   16篇
  2017年   7篇
  2016年   6篇
  2015年   7篇
  2014年   11篇
  2013年   19篇
  2012年   9篇
  2011年   20篇
  2010年   8篇
  2009年   22篇
  2008年   16篇
  2007年   14篇
  2006年   10篇
  2005年   12篇
  2004年   13篇
  2003年   24篇
  2002年   10篇
  2001年   14篇
  2000年   8篇
  1999年   38篇
  1998年   472篇
  1997年   278篇
  1996年   189篇
  1995年   149篇
  1994年   94篇
  1993年   91篇
  1992年   20篇
  1991年   19篇
  1990年   20篇
  1989年   9篇
  1988年   12篇
  1987年   13篇
  1986年   7篇
  1985年   10篇
  1983年   5篇
  1982年   7篇
  1981年   14篇
  1980年   20篇
  1979年   5篇
  1978年   8篇
  1977年   60篇
  1976年   104篇
  1975年   5篇
  1974年   4篇
  1971年   3篇
排序方式: 共有1948条查询结果,搜索用时 15 毫秒
1.
The separation of iron oxide from banded hematite jasper(BHJ) assaying 47.8% Fe, 25.6% Si O2 and 2.30%Al2O3 using selective magnetic coating was studied. Characterization studies of the low grade ore indicate that besides hematite and goethite,jasper, a microcrystalline form of quartzite, is the major impurity associated with this ore. Beneficiation by conventional magnetic separation technique could yield a magnetic concentrate containing 60.8% Fe with 51% Fe recovery. In order to enhance the recovery of the iron oxide minerals, fine magnetite, colloidal magnetite and oleate colloidal magnetite were used as the coating material. When subjected to magnetic separation, the coated ore produces an iron concentrate containing 60.2% Fe with an enhanced recovery of56%. The AFM studies indicate that the coagulation of hematite particles with the oleate colloidal magnetite facilitates the higher recovery of iron particles from the low grade BHJ iron ore under appropriate conditions.  相似文献   
2.
We characterize the meander of re-entrant excitation in a model of a sheet of mammalian ventricular tissue, and its control by resonant drift under feedback driven stimulation. The Oxsoft equations for excitability in a guinea pig single ventricular cell were incorporated in a two dimensional reaction-diffusion system to model homogeneous, isotropic tissue with a plane wave conduction velocity of 0.35 m s-1. Re-entrant spiral wave solutions have a spatially extended transient motion (linear core) that settles down into rotation with an irregular period of 100-110 ms around an irregular, multi-lobed spiky core. In anisotropic tissue this would appear as a linear conduction block. The typical velocity of drift of the spiral wave induced by low amplitude resonant forcing is 0.4 cm s-1.  相似文献   
3.
The report deals with the development of procedures, evaluation of laser application and prevention of complications involved in intensive chemoradiation therapy of neoplasms of hemopoietic and lymphoid tissue in childhood. The clinical data on 548 patients, aged 2 months-15 years, with leukemia and solid tumor were evaluated. Laser application for treatment of different complications of chemoradiation therapy of pediatric leukemia proved a valuable innovation. It had a pronounced antiinflammatory and analgetic effect, promoted tissue regeneration processes and cut down the duration of complication treatment drastically.  相似文献   
4.
5.
6.
7.
Gonadotropin-releasing hormone (GnRH) molecular variants in the brain and pituitary gland of pejerrey, Odontesthes bonariensis (Atheriniformes), were characterized by gradient reverse phase high performance liquid chromatography (RP-HPLC). Eluted fractions were tested in radioimmunoassays with different antisera. The results show that the brain extract contains three forms of GnRH: one is immunologically and chromatographically similar to cIIGnRH (chicken II), and another is similar to sGnRH (salmon). A third GnRH appears to be chromatographic and immunologically different from the nine other known forms of the vertebrate hormone. This is the only variant present in the pituitary gland.  相似文献   
8.
9.
Investigated all links of oxygen homeostasis of patients in early period afterwards surgical stoppage gastro-intestinal bleeding and urgent intravascular volume replacement. Macrodelivery of oxygen (DO2) was reduced in two and more time in comparison with norm predominant in connection with anemia. In spite of the infringement of transport of oxygen through alveolar-capillary membrane (especially in patients with complications and death in early postoperative period), little affected of degree of hemoglobin saturation by oxygen. Despite decrease of erythrocyte zeta-potential, largely expressed in cases of lethal outcome, considerable infringement of passage through microcirculation vessels is fixed was not. The increase of degree of morbidity and anaerobic metabolism in early postoperative period was accompanied of hyperdynamic hemodynamic reaction. The increase of degree of morbidity was accompanied of increase oxygen deficit owing to infringement of oxidoreduction in fabries also.  相似文献   
10.
RATIONALE AND OBJECTIVES: We compared adverse reactions and image quality for hysterosalpingography (HSG) performed with ionic (diatrizoate meglumine combined with iodipamide meglumine [DM + IM]) and nonionic (iohexol) contrast media. METHODS: We performed a study of 95 patients who had HSG and were randomly selected to receive DM + IM or iohexol. Patients reported episodes of abdominal pain and other adverse reactions immediately and 24 hr after the procedure and categorized severity of symptoms on a subjective scale. Two radiologists evaluated image quality for diagnosis. RESULTS: Prevalence of abdominal pain and other reactions both immediately and 24 hr after HSG was lower in patients who received iohexol than in patients who received DM + IM. Moderate or severe abdominal pain was significantly lower in the iohexol group than in the DM + IM group (p < .05). Visualization of the uterine cavity and ampullary rugae was judged excellent with both contrast media (87% with iohexol and 92% with DM + IM). CONCLUSION: Iohexol and DM + IM are excellent contrast media for use during HSG; iohexol 300 may cause fewer episodes of more severe and prolonged abdominal pain.  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