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   4948篇
  免费   4篇
电工技术   15篇
综合类   1篇
化学工业   225篇
金属工艺   72篇
机械仪表   111篇
建筑科学   9篇
矿业工程   20篇
能源动力   6篇
轻工业   7篇
水利工程   8篇
石油天然气   76篇
无线电   218篇
一般工业技术   605篇
冶金工业   3344篇
原子能技术   148篇
自动化技术   87篇
  2021年   25篇
  2020年   31篇
  2019年   43篇
  2018年   57篇
  2017年   42篇
  2016年   56篇
  2014年   46篇
  2013年   54篇
  2012年   45篇
  2011年   41篇
  2010年   49篇
  2009年   43篇
  2008年   35篇
  2007年   37篇
  2006年   34篇
  2005年   37篇
  2004年   32篇
  2003年   27篇
  2002年   25篇
  2001年   29篇
  1999年   87篇
  1998年   954篇
  1997年   560篇
  1996年   411篇
  1995年   261篇
  1994年   178篇
  1993年   202篇
  1992年   42篇
  1991年   50篇
  1990年   51篇
  1989年   55篇
  1988年   46篇
  1987年   46篇
  1986年   43篇
  1985年   47篇
  1984年   36篇
  1983年   31篇
  1982年   49篇
  1981年   55篇
  1980年   66篇
  1979年   40篇
  1978年   36篇
  1977年   179篇
  1976年   290篇
  1975年   41篇
  1974年   23篇
  1973年   26篇
  1972年   26篇
  1971年   30篇
  1966年   23篇
排序方式: 共有4952条查询结果,搜索用时 46 毫秒
51.
Two cases of female patients operated fo the tumors of the stomach are presented. Result of histologic examination was rather surprising in both cases--leiomyoma.  相似文献   
52.
53.
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   
54.
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   
55.
56.
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   
57.
58.
59.
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   
60.
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