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   4206篇
  免费   37篇
电工技术   9篇
化学工业   78篇
金属工艺   13篇
机械仪表   9篇
建筑科学   9篇
能源动力   6篇
轻工业   38篇
水利工程   1篇
石油天然气   4篇
无线电   25篇
一般工业技术   108篇
冶金工业   3901篇
原子能技术   1篇
自动化技术   41篇
  2023年   5篇
  2022年   7篇
  2021年   10篇
  2020年   13篇
  2019年   12篇
  2018年   11篇
  2017年   18篇
  2016年   11篇
  2015年   12篇
  2014年   14篇
  2013年   18篇
  2012年   21篇
  2011年   20篇
  2010年   10篇
  2009年   15篇
  2008年   18篇
  2007年   15篇
  2006年   13篇
  2005年   13篇
  2004年   13篇
  2003年   24篇
  2002年   14篇
  2001年   6篇
  2000年   6篇
  1999年   122篇
  1998年   1269篇
  1997年   748篇
  1996年   483篇
  1995年   249篇
  1994年   173篇
  1993年   227篇
  1992年   20篇
  1991年   46篇
  1990年   45篇
  1989年   45篇
  1988年   49篇
  1987年   37篇
  1986年   37篇
  1985年   31篇
  1983年   6篇
  1982年   12篇
  1981年   14篇
  1980年   31篇
  1979年   4篇
  1978年   7篇
  1977年   77篇
  1976年   182篇
  1975年   4篇
  1964年   1篇
  1955年   4篇
排序方式: 共有4243条查询结果,搜索用时 15 毫秒
81.
82.
The rate of nosocomial respiratory syncytial virus (RSV) infection was measured in a large pediatric hospital using an incidence density method. The at-risk days for nosocomial RSV were summed during a defined winter period in which there were 54 admissions with community-acquired RSV infection giving a rate of 2.9 cases per 1,000 at-risk days (95% confidence interval, 0.3-5.4 per 1,000).  相似文献   
83.
84.
Only 19 cases of metastases at the cannula insertion site after laparoscopy for gynecological malignancy have been reported in the literature. One case has been diagnosed with cervical squamous cell carcinoma, whereas the others have been diagnosed with ovarian cancer and borderline ovarian tumor. We present a novel case of laparoscopy-site abdominal wall metastasis from endometrial cancer after laparoscopic-assisted vaginal hysterectomy (LAVH). The 56-year-old female patient exhibited metastases of an abdominal wall trocar site and a perineal site after undergoing LAVH and laparoscopic-assisted (LA) bilateral pelvic lymph node sampling as well as LA para-aortic lymph node sampling for treating endometrial carcinoma, surgical staging IIIC, G3. The interval between the surgical extirpation of endometrial carcinoma and diagnosis of the tumor recurrence was 6 months, suggesting that overmanipulation of the diseased organ during laparoscopic surgery may have resulted in tumor spillage, intraperitoneal dissemination, and wound contamination. Although this procedure has been proven beneficial to patients with benign disease or early-stage gynecologic malignancies, laparoscopic-assisted vaginal hysterectomy may not be efficacious to eradicate advanced gynecological malignancy.  相似文献   
85.
Acute, monophasic experimental allergic encephalomyelitis (EAE) in the Lewis rat shows pathological similarities to the human disease multiple sclerosis (MS). Rats that recover from EAE are essentially resistant to disease reinduction, unlike MS in which relapses are frequently associated with common bacterial and viral infections. As macrophage-derived interleukin (IL)-12 is a critical component of innate resistance to bacterial infection and appears to directly activate encephalitogenic T cells in vivo, the ability of this cytokine to reinduce paralysis in EAE was examined. Paralytic disease was exacerbated by intraperitoneal IL-12 administration and could be reinduced up to 1 week after recovery from the primary clinical episode. Concomitant with worsening of initial clinical signs and relapse was an increase in the ratio of macrophages to T cells in brain stem perivascular cuffs and the expression of inducible nitric oxide synthase in cells with both macrophage and microglial morphology. These findings suggest that IL-12 may contribute to macrophage-mediated disease exacerbation and relapse in patients with MS.  相似文献   
86.
87.
88.
89.
Human infection with a zoonotic Brugia species in the United States is uncommon. Positive identification of the filarial nematode is required for histopathologic diagnosis. Many cases may go unrecognized because of the nonspecific clinical manifestations and the nondiagnostic histologic changes occurring in involved lymph nodes. A case of zoonotic Brugia lymphadenitis is described in a patient from Rhode Island, in which a small nongravid female worm was identified in a lymph node biopsy specimen. The lymph node also showed a spectrum of reaction changes including the presence of florid monocytoid B-cell proliferation, which has not been described in association with zoonotic Brugian filariasis.  相似文献   
90.
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