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   469篇
  免费   0篇
电工技术   1篇
化学工业   6篇
能源动力   1篇
轻工业   4篇
石油天然气   1篇
一般工业技术   4篇
冶金工业   442篇
原子能技术   8篇
自动化技术   2篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2011年   1篇
  2010年   1篇
  2007年   1篇
  2006年   1篇
  2005年   1篇
  2003年   1篇
  2002年   1篇
  2000年   1篇
  1999年   9篇
  1998年   120篇
  1997年   80篇
  1996年   53篇
  1995年   27篇
  1994年   25篇
  1993年   18篇
  1992年   7篇
  1991年   5篇
  1990年   5篇
  1989年   4篇
  1988年   5篇
  1987年   16篇
  1986年   6篇
  1985年   4篇
  1984年   1篇
  1983年   1篇
  1982年   4篇
  1981年   7篇
  1980年   2篇
  1979年   1篇
  1978年   2篇
  1977年   19篇
  1976年   28篇
  1975年   1篇
  1973年   1篇
  1970年   3篇
  1968年   1篇
  1967年   1篇
  1965年   1篇
  1962年   1篇
排序方式: 共有469条查询结果,搜索用时 31 毫秒
461.
The phenomenon of Hydrachnidae association with the tick-borne encephalitic viruses complex has been found out during the study of the role of the Hydrachnidae in the arboviruses circulation. We investigated the fauna, studied the quantity variation and trophic relations of these arthropods and blood-sucking Diptera. It was revealed no trophic relations between blood-sucking Diptera and mite species, where TBE strains were isolated from. On the basis of faunistic and virological study we suppose, that Hydroacarinae got an infection with the virus in the nymphal and imago stages, as well as larvae of mosquitos. Authors also note, that trophic relations between blood-sucking Diptera and chiggers (Trombidiidae) may be important in the arboviruses ecology.  相似文献   
462.
A systematic search for cases of adult-onset hereditary ataxia was conducted on location in Scotland. The investigation resulted in the discovery of eight pedigrees with 42 patients of whom 16 were alive in 1975. Nine patients were examined by the authors and recent hospital records were available on the remaining seven. The clinical features were quite variable. In declining order of frequency, findings were gait and limb ataxia, dysarthria, hyperreflexia, extrapyramidal motor disturbances, impaired vibratory sense, spasticity, defects of extraocular movements and nystagmus, reflex depression, Babinski signs, impaired joint position sense, muscle weakness, optic atrophy, and mental abnormalities. Foot deformity occurred only once. Inheritance was compatible with autosomal dominant transmission, but complicated by consanguinity in two families. The minimum prevalence was calculated as 0.31/100,000. Autopsy in two members in one family revealed olivopontocerebellar degeneration.  相似文献   
463.
Twelve patients with bilateral symptomatic lesions of internal carotid arteries have had bilateral carotid endarterectomy at single operations without complications. These were patients up to age 80 who had prior mycardial infarction, stroke with recovery, and hemispheric and nonhemispheric episodes. Neurologist's clearance and three- or four-vessel intracranial-extracranial angiography preceded all operations, which were performed with the patient under general anesthesia. Stump pressure measurements were the principal guideline of adequacy of collateral flow and predictor of safe outcome. The safety of this concept of bilateral operations during one anesthesia can eliminate uncertainties of sequence and timing, obviate delay and indecision, and avoid the hazards of a second anesthetic-operative experience.  相似文献   
464.
Survey forms were sent to 360 Ob./Gyn, residency programs in the United States and Canada with responses from 279 concerning usage of various types of fetal monitoring. The results are presented and discussed.  相似文献   
465.
Kaolin-induced hydrosyringomyelia in dogs has been investigated by radioisotope ventriculography using both cerebrospinal fluid radioassay and scintigraphy. The hydromyelic central canal can be differentiated from the spinal subarachnoid space by scintigraphy, Serial studies show that hydromyelia arises rapidly to decompress the associated hydrocephalus in surviving animals. Syringomyelia, after a delayed onset, originates from the enlarged central canal. Radioisotope ventriculography may be a useful clinical aid in the diagnosis of hydrosyringomyelia.  相似文献   
466.
1H-NMR and circular dichroism studies have been carried out on osteocalcin, a 49-residue, calcium-binding protein, the sequence of which contains a disulphide bridge, a proline-rich segment and three gamma-carboxyglutamic acid (Gla) residues. These latter residues have been proposed to lie on one face of an alpha helix and interact with the mineral phase, leading to incorporation of the protein into the bone matrix. Circular dichroism shows an increase in the alpha-helical structure on Ca2+ binding to bovine osteocalcin. This induced structure is lost on heating the protein, giving a spectrum close to that of the Ca(2+)-free protein. 1H-NMR studies of rabbit osteocalcin gave a set of resonance assignments and NOEs which could be interpreted in terms of distance constraints. These did not allow a single conformation to be defined for the protein in solution but reflect rather a flexible structure which may be essential for the function of the protein. The calculated structures contain a hydrophobic core (comprising Leu2, Leu32, Val36 and Tyr42, seen to be slowly flipping in the Ca(2+)-bound form) and have the gamma-carboxyglutamic acid side chains exposed on one face of the molecule.  相似文献   
467.
Monomeric products of the 5,6-dihydroxy-dihydrothymine type are produced in the DNA by both ultraviolet and ionizing radiations. The capacity of nuclear preparations from normal and Xeroderma pigmentosum (XP) cells (Complementation groups A, B, C and D) to excise such products from ultraviolet or gamma-irradiated T7DNA was comparable and was independent of radiation induced strand breaks.  相似文献   
468.
469.
Kumar  PV Arul  Vivek  J.  Senniangiri  N.  Nagarajan  S.  Chandrasekaran  K. 《SILICON》2022,14(4):1831-1849
Silicon - Carbon Fiber Reinforced Polymers (CFRPs) have been applied potentially for various application components owing to their lightweight and better mechanical properties. However, the...  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