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   2703篇
  免费   12篇
电工技术   21篇
综合类   1篇
化学工业   132篇
金属工艺   27篇
机械仪表   15篇
建筑科学   36篇
矿业工程   1篇
能源动力   16篇
轻工业   97篇
水利工程   14篇
石油天然气   1篇
无线电   75篇
一般工业技术   168篇
冶金工业   1979篇
原子能技术   9篇
自动化技术   123篇
  2021年   5篇
  2019年   7篇
  2017年   7篇
  2016年   8篇
  2015年   5篇
  2014年   8篇
  2013年   107篇
  2012年   19篇
  2011年   36篇
  2010年   24篇
  2009年   29篇
  2008年   25篇
  2007年   37篇
  2006年   25篇
  2005年   37篇
  2004年   26篇
  2003年   29篇
  2002年   27篇
  2001年   24篇
  2000年   21篇
  1999年   65篇
  1998年   591篇
  1997年   327篇
  1996年   242篇
  1995年   119篇
  1994年   135篇
  1993年   113篇
  1992年   32篇
  1991年   37篇
  1990年   34篇
  1989年   30篇
  1988年   39篇
  1987年   29篇
  1986年   34篇
  1985年   42篇
  1984年   10篇
  1983年   14篇
  1982年   18篇
  1981年   17篇
  1980年   24篇
  1979年   5篇
  1978年   13篇
  1977年   46篇
  1976年   112篇
  1975年   12篇
  1973年   5篇
  1971年   6篇
  1968年   4篇
  1967年   4篇
  1966年   5篇
排序方式: 共有2715条查询结果,搜索用时 31 毫秒
21.
Uterine angiomyolipomas are rare lesions composed of mature adipose tissue, smooth muscle, fibrous connective tissue, and blood vessels in varying proportions. We reported the first case of angiomyolipoma associated with a normal pregnancy. Initially, the tumor developed intramurally and could have been confused with a partial molar gestation. After delivery, tumor development was extensive and subserosal, making differential diagnosis from a sarcoma difficult. The question of histological diagnosis, as well as that of immunocytochemical analysis which seems to be helpful in such cases, is discussed here.  相似文献   
22.
23.
The known effects of commonly used nonsteroidal anti-inflammatory drugs (NSAIDs) on hemostatic parameters have led to concern over their use in the perioperative period. Nabumetone, unlike other NSAIDs, has little effect on collagen-induced platelet aggregation. To evaluate the effect of nabumetone 2000 mg daily on other hemostatic parameters (e.g., bleeding time, prothrombin time, and partial thromboplastin time) in the clinical setting, this double-masked study was conducted in patients with osteoarthritis undergoing arthroscopic knee surgery. After a 1-week placebo washout period, 58 patients were randomized to receive nabumetone and 53 were randomized to receive placebo. They were assessed before surgery (after 1 to 2 weeks of treatment) and again after surgery (after an additional 3 weeks of treatment). The study was designed to have 90% power to show equivalence in bleeding time to within 1.5 minutes, a difference assumed to be of no clinical importance. No meaningful differences were observed between the groups in any of the measured hemostatic parameters. Before surgery, the bleeding time increased by only 0.3 minutes with nabumetone and decreased by 0.2 minutes with placebo. The mean (+/- SD) difference between the groups in change from baseline was 0.5 +/- 0.3 minutes. After surgery, the changes were 0.1 minutes and 0.0 minutes, respectively, and the difference between groups was 0.2 +/- 0.3 minutes. These differences were neither statistically nor clinically significant, and maximum individual increases were similar in each group. Furthermore, there were no reports of abnormal bleeding in the operative knees. The results of this study show that nabumetone had little or no effect on hemostasis and suggest that this drug can be used safely in the perioperative period.  相似文献   
24.
25.
26.
27.
28.
29.
Data from the Cancer Registry of Slovenia were used in a cohort study to determine whether the incidence of second primary cancers in patients with first primary breast cancer differs from the incidence expected in the general population. Special interest was given to long-term survivors. The expected numbers of second primary cancers were calculated by multiplying the number of appropriate person-years at risk by the corresponding age- and calendar-period-specific cancer incidence rates for women in Slovenia. The risk of a second primary cancer was expressed as the standardized incidence ratio (SIR). Of the 8,917 patients newly diagnosed in the period 1961-85 and followed-up to the end of 1994, 547 (6.2 percent) developed second primary cancers, whereas 410 (4.7 percent) were expected (SIR = 1.3, 95 percent confidence interval [CI] = 1.2-1.4). The risk was higher among younger patients. In long-term survivors, the risk was increased significantly for second primary cancer of the breast (SIR = 1.4, CI = 1.1-1.7), lung cancer (SIR = 1.6, CI = 1.1-2.3), melanoma (SIR = 2.7, CI = 1.5-4.4) and non-melanoma skin cancers(SIR = 2.0, CI = 1.6-2.4), corpus uteri cancer(SIR = 1.6, CI = 1.2-2.1), ovarian cancer(SIR = 2.3, CI = 1.7-3.0), and thyroid cancer (SIR = 2.5, CI = 1.2-4.6). Our results confirm the findings of several cohort studies carried out in Europe, the United States, and Japan, indicating that breast cancer patients should be monitored carefully for the occurrence of second primary cancers.  相似文献   
30.
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