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   3228篇
  免费   1篇
电工技术   1篇
化学工业   17篇
金属工艺   4篇
建筑科学   2篇
矿业工程   2篇
能源动力   2篇
轻工业   15篇
石油天然气   1篇
无线电   1篇
一般工业技术   5篇
冶金工业   3170篇
原子能技术   1篇
自动化技术   8篇
  2020年   2篇
  2018年   1篇
  2015年   1篇
  2013年   2篇
  2012年   4篇
  2011年   3篇
  2010年   2篇
  2008年   2篇
  2007年   2篇
  2006年   4篇
  2005年   4篇
  2004年   4篇
  2003年   4篇
  1999年   70篇
  1998年   924篇
  1997年   538篇
  1996年   391篇
  1995年   236篇
  1994年   163篇
  1993年   183篇
  1992年   20篇
  1991年   33篇
  1990年   27篇
  1989年   30篇
  1988年   24篇
  1987年   19篇
  1986年   18篇
  1985年   19篇
  1983年   6篇
  1982年   19篇
  1981年   25篇
  1980年   33篇
  1979年   3篇
  1978年   11篇
  1977年   131篇
  1976年   258篇
  1975年   9篇
  1973年   1篇
  1965年   1篇
  1964年   1篇
  1954年   1篇
排序方式: 共有3229条查询结果,搜索用时 15 毫秒
41.
42.
Livedo racemosa with cerebrovascular lesions has been described as Ehrmann-Sneddon syndrome. The etiopathogenetic factors provoking the vascular lesions, however, are of high diversity reaching from mechanical to autoimmune causes. We present a male patient with typical livedo racemosa, muscle pain and feeling of coldness of the forearms. By dermatohistopathology and magnetic resonance tomography of the brain, Ehrmann-Sneddon syndrome could be confirmed. At this time a chronic streptococcal infection could be diagnosed. Antibiotics, anticoagulants and vascularity-supplying therapy improved the clinical and subjective symptoms. Six months later, the patient developed dizziness, vision disorder, hypesthesia of the right forehead, malaise and weight loss. A further diagnostic workup including echocardiography revealed a myxoma of the left atrium. This report illustrates the association of Ehrmann-Sneddon syndrome with cardiac myxoma and points out that cardiac diagnostic examination should be included when dealing with small-vessel involvement of the brain.  相似文献   
43.
OBJECTIVE: To determine if patients with the Guillain-Barré syndrome are likely to have had Campylobacter jejuni infection before onset of neurologic symptoms. DESIGN: A case-control study. SETTING: Several university medical centers. PATIENTS: Case patients met clinical criteria for the Guillain-Barré syndrome between 1983 and 1990 and had a serum sample collected and frozen within 3 weeks after onset of neurologic symptoms (n = 118). Disease controls were patients with other neurologic illnesses (n = 56); healthy controls were hospital employees or healthy family members of patients (n = 47). MEASUREMENTS: Serum IgA, IgG, and IgM antibodies to C. jejuni were determined by enzyme-linked immunosorbent assays. Assays were done in a blinded manner. RESULTS: Optical density ratios > or = 2 in two or more immunoglobulin classes were seen in 43 (36%) of patients with the Guillain-Barré syndrome and in 10 (10%) of controls (odds ratio, 5.3; 95% CI, 2.4 to 12.5; P < 0.001). Increasing the optical density ratio or the number of immunoglobulin classes necessary to yield a positive result increased the strength of the association. The number of patients with the Guillain-Barré syndrome who had positive serologic responses was greatest from September to November (P = 0.02). Male patients were three times more likely to have serologic evidence of C. jejuni infection (P = 0.009); the proportion of patients with the syndrome who had a positive serologic response increased with age. CONCLUSIONS: Patients with the Guillain-Barré syndrome are more likely than controls to have serologic evidence of C. jejuni infection in the weeks before onset of neurologic symptoms. Campylobacter jejuni may play a role in the initiation of the Guillain-Barré syndrome in many patients.  相似文献   
44.
45.
In the review there analyzed the results of ground-based studies of rotation effects (at a gravity value near 1 g) on the animals, the experimental findings to determine a minimum effective value of artificial gravity as well as the data of biosatellite experiments. The major trends of animal studies in the artificial gravity area is presented.  相似文献   
46.
47.
48.
Exposure of Farage, a human B-cell line, to interleukin 4 (IL4) reduced the amount of CD38 antigen on the surface of the cells and in cell lysates. No evidence was obtained for accelerated breakdown, shedding, or internalization of CD38 molecules following IL4 treatment, nor the accumulation of CD38 molecules in the cell interior. The inhibition of protein synthesis with cycloheximide (CXM) diminished the down-regulation of CD38 induced by IL4. CXM decreased the expression of CD38 in Farage cells with arrested mitosis, and IL4 failed to further reduce CD38 expression. Staurosporine, an inhibitor of serine/threonine protein kinases, and H7 (1-(5-isoquinolinylsulfonyl)-2-methylpiperazine), a preferential inhibitor of protein kinase C (PKC), abrogated the effect of IL4 on CD38, while inhibitors of other serine protein kinases W7 (N-(aminohexyl)-5-chloro-1-naphthalenesulfoamide) and H8 (N-(2-[methylamino]ethyl)-5-isoquinolinesulfonamide) failed to interfere with the effect of IL4. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, resembled IL4 in decreasing the expression of CD38, and either staurosporine or H7 abolished this effect. Genistein, an inhibitor of tyrosine kinases, increased the expression of CD38, but failed to abrogate the inhibitory effect of IL4 on CD38. It is concluded that serine/threonine protein kinases mediated the IL4-induced down-regulation of the expression of CD38 molecules in B cells.  相似文献   
49.
50.
Through TCD test, observation on the blood flow dynamics change before and after treatment with 31 cases of the child cerebral atrophy was made. It is found that scalp therapy is able to speed up the blood flow of part artery, especially increase the even blood flow speed of MCA, ACA obviously (P < 0.05), which preliminary shows the mechanism of scalp therapy for child cerebral atrophy mean while. It is found that scalp therapy also has the function to restrain epilepsy.  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