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   872篇
  免费   1篇
化学工业   14篇
建筑科学   5篇
能源动力   4篇
轻工业   12篇
无线电   9篇
一般工业技术   28篇
冶金工业   761篇
原子能技术   2篇
自动化技术   38篇
  2019年   2篇
  2017年   2篇
  2016年   2篇
  2015年   1篇
  2014年   3篇
  2013年   25篇
  2012年   3篇
  2011年   3篇
  2009年   3篇
  2008年   1篇
  2006年   2篇
  2004年   2篇
  2003年   3篇
  2002年   3篇
  2001年   2篇
  2000年   3篇
  1999年   20篇
  1998年   241篇
  1997年   112篇
  1996年   78篇
  1995年   54篇
  1994年   48篇
  1993年   41篇
  1992年   8篇
  1991年   13篇
  1990年   17篇
  1989年   13篇
  1988年   15篇
  1987年   12篇
  1986年   11篇
  1985年   12篇
  1984年   3篇
  1983年   3篇
  1982年   3篇
  1981年   5篇
  1980年   8篇
  1979年   1篇
  1978年   5篇
  1977年   16篇
  1976年   64篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1971年   2篇
  1970年   2篇
  1965年   1篇
  1955年   1篇
排序方式: 共有873条查询结果,搜索用时 259 毫秒
1.
A prospective longitudinal study of patients with early RA was performed to examine the influence of disease duration, disease activity and physical activity on bone loss. Sixty-seven patients with non-steroid treated RA of less than 5 yr duration, including 16 patients with disease duration less than 6 months, had BMD measurements of the femoral neck and the lumbar spine over a 12-month period using dual energy X-ray absorptiometry. The BMD changes were compared with values from 72 control patients and were also correlated with serial measurements of disease activity (measured by the Stoke Index) and disability [measured by the Health Assessment Questionnaire (HAQ) score], at 3-monthly intervals over the 12-month period. No significant differences in BMD changes were found between RA patients and controls overall. Patients with disease duration of less than 6 months had significantly greater loss of BMD at the femoral neck (-3.9%, S.E.M. 1.5) than the remainder of the cohort (-0.2%, S.E.M. 0.7) (P = 0.02) and controls (-0.8%, S.E.M. 0.6). Lumbar spine BMD changes correlated with the initial Stoke Index (Rs-0.373, P = 0.01) but not mean Stoke Indices. There was no correlation of BMD changes with age or HAQ scores. These findings suggest that significant bone loss occurs within the first few months of disease in patients with RA.  相似文献   
2.
Although there have been recent molecular biological studies for evidence of possible changes in trypanosome biochemistry, such studies are not yet complemented by parallel clinical studies to determine the possible implications to the sleeping sickness patient. The study of the duration of symptoms and the case fatality of T. b. rhodesiense showed that the disease progressed to the stage of central nervous system involvement between three weeks to two months of infection. Most (> 80%) deaths occurred within six months of illness. The case fatality rate of treated sleeping sickness patients was 6% of which the rate in the late-stage of sleeping sickness was more than two and a half times that in the early stage. The incidence of melarsoprol encephalopathy was 2.5% and case fatality due to this condition was 1.0% and similar to previous findings. Thus it appears the virulence of T. b. rhodesiense circulating in south east Uganda has not changed during the past decades.  相似文献   
3.
Rotational and functional motor behavioral changes were studied in five MPTP lesioned chronic hemiparkinsonian Macaca nemestrina monkeys after i.m. pramipexole, a predominant D2 subfamily agonist. Pramipexole induced contraversive rotations in a dose-dependent manner with an optimal dose of 56 microg/kg for approximately 2 to 4 hr after injection. Three different rating scales were used to determine drug-induced functional improvement. They included a monkey parkinsonism rating scale, volitional responses to fruit presentations, and number of hand movements that appeared volitional. A dose of 56 microg/kg of pramipexole produced functional improvements on hand disability, and on a parkinsonian rating scale for monkeys in a dose-dependent manner from 32 to 100 microg/kg. These doses produced an increase in significant hand movements in the affected (contralateral) as well as in the normal (ipsilateral) hand to the side of the brain lesion compared with 5% dextrose in water vehicle control. With a dose of 100 microg/kg, the therapeutic effects of pramipexole on hand movements were less than with 56 microg/kg, due to side effects such as scratching.  相似文献   
4.
Radiation therapy exerts both acute and chronic effects on normal tissue included within treatment fields. The physics of radiation therapy and treatment techniques to minimize deleterious effects of radiation are presented. Management of radiation-damaged skin is discussed. Radiation effect on tissue, wound healing, and tumorigenesis also are reviewed.  相似文献   
5.
The present study, based on 158 HIV seropositives and 167 HIV seronegatives, demonstrates that saliva collected with the Omni-SAL device and tested with GACELISA (an IgG antibody capture ELISA) is an effective non-invasive alternative to serum for anti-HIV IgG antibody screening. The study also shows that a conventional serum Western blot kit can be used, with slight modifications, for confirmatory testing of saliva specimens. Collecting saliva with the Omni-SAL device had a very good acceptance rate among Tanzanian subjects, and although this diagnostic method is not yet known by the general public, 65% of the study participants preferred to give saliva instead of blood for HIV testing.  相似文献   
6.
7.
8.
For discrete systems, the set of all state covariances X which can be assigned to the closed-loop system via a dynamic controller is characterized explicitly. For any assignable state covariance X , the set of all controllers that assign this X to the closed-loop system is parameterized with an arbitrary orthonormal matrix U of proper dimension  相似文献   
9.
10.
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