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   679篇
  免费   0篇
  国内免费   1篇
电工技术   1篇
化学工业   4篇
金属工艺   1篇
矿业工程   1篇
能源动力   1篇
无线电   2篇
一般工业技术   3篇
冶金工业   665篇
自动化技术   2篇
  2020年   1篇
  2013年   1篇
  2012年   1篇
  2004年   3篇
  2003年   1篇
  2002年   1篇
  2000年   1篇
  1999年   23篇
  1998年   195篇
  1997年   109篇
  1996年   78篇
  1995年   46篇
  1994年   26篇
  1993年   50篇
  1992年   16篇
  1991年   11篇
  1990年   8篇
  1989年   11篇
  1988年   6篇
  1987年   6篇
  1986年   5篇
  1985年   8篇
  1983年   1篇
  1982年   1篇
  1981年   4篇
  1980年   4篇
  1979年   1篇
  1978年   1篇
  1977年   19篇
  1976年   37篇
  1975年   1篇
  1968年   1篇
  1963年   1篇
  1960年   1篇
  1955年   1篇
排序方式: 共有680条查询结果,搜索用时 15 毫秒
111.
112.
113.
The MURCS association is traditionally regarded as a disorder limited to the female sex. It has been hypothesized that men displaying the combination of azoospermia, segmentation abnormalities of the cervicothoracic spine and renal anomalies may have a male analogue of MURCS. Here we describe a patient with non-obstructive azoospermia and Klippel-Feil anomaly type II and suggest that this may represent another case of 'MURCS in the male'.  相似文献   
114.
Spermine decreased distinctly the activity of Ca2+ -phospholipid-dependent protein kinases, whereas not affected the protein kinase A activity. Content of cytosol estradiol receptors was drastically decreased in rat uterine in presence of the polyamine. The data obtained and literature data suggest that activation of estradiol receptors appears to occur after phosphorylation by means of Ca2+ - dependent protein kinases, which are regulated via phosphoinositide-involving mechanism, i.e. these receptors acquire the ability to bind hormones.  相似文献   
115.
116.
The effect of low-energy infrared laser irradiation on the phospholipid pool, lipid peroxidation, and superoxide dismutase activity in the brain of white rats was studied in experimental ischemia, reperfusion, and acute edema. These models are characterized by oxidative stress; the contents of tri- and diphosphoinositides and sphingomyelins were lowered, whereas the levels of phosphatidylserine and phosphatidylethanolamine did not change, and the amount of phosphatidylcholine was increased. In acute brain edema, the contents of hydroperoxides and malonic dialdehyde in enzymatic and nonenzymic lipid peroxidation systems were increased in mitochondrial and microsomal fractions and the level of arachidonic acid was significantly elevated. Infrared laser irradiation contributes to the correction of the changes in the phospholipid pool; laser irradiation lowered the increased levels of hydroperoxides and malonic dialdehyde and elevated superoxide dismutase activity in the brain during ischemia, reperfusion, and acute edema of the brain. The data suggest that low-energy infrared laser irradiation has certain neuroprotective activity in various types of oxidative stress including ischemia, reperfusion, and acute edema of the brain.  相似文献   
117.
118.
An anonymous postal survey was undertaken to assess the frequency of hygiene service engineers finding sharp objects (including needles) in the washrooms in which they worked. Data on the type of sharps found and their exact location were collected along with information on the type and number of accidents which had occurred. As a result of the survey it was clear that, although the number of recorded accidents was small, a significant number of accidents were not being reported and that finding sharps was a common occurrence for these workers. Recommendations to management on working practises and procedures and on the need for immunization are outlined.  相似文献   
119.
OBJECTIVE: To evaluate the impact of HIV illness on psychiatric and psychosocial functioning over 3 years in a sample of male and female HIV-positive injecting drug users (IDU), with a comparison group of HIV-negative male and female IDU. DESIGN: As part of a multidisciplinary study, 121 men (69 HIV-positive, 52 HIV-negative) and 66 women (36 HIV-positive, 30 HIV-negative) were evaluated semiannually for seven visits. Attrition, unrelated to sex or serostatus, was 33%. RESULTS: At baseline, rates of major depression and dysthymia ranged from 15% (HIV-negative men) to 33% (HIV-positive men and HIV-negative women). Global impairment was in the range found in psychiatric patients (mean Global Assessment of Functioning scores, 46-51). Higher levels of social support and less social conflict were independently associated with decreased distress and improved global functioning among both men and women. For both HIV-positive groups, degree of improvement over time was related to degree to HIV progression: those who remained healthier in terms of CD4 count and illness stage showed more improvement. HIV-seronegative status was associated with less distress for men but not for women. Overall, women reported higher levels of psychiatric distress than men. CONCLUSIONS: High rates of psychopathology were found in this IDU cohort, independent of HIV status and sex. Although rates of psychopathology, injecting drug use and distress declined slightly during the study, they remained elevated; accordingly, psychiatric services are indicated for this population.  相似文献   
120.
We report a 38-year-old female of Puerto Rican descent with Hermansky-Pudlak syndrome and decreased levels of von Willebrand factor. Histologic and ultrastructural findings of non-sunexposed skin showed melanocytes with short dendritic processes and decreased numbers of melanosomes. Ultrastructural examination of platelets revealed greatly reduced numbers of delta granules. Recognition of this syndrome is important because skin neoplasms, ceroid deposition and hemorrhagic manifestations can be causes of morbidity and of potential death in patients affected with this syndrome.  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