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   2172篇
  免费   11篇
  国内免费   1篇
电工技术   6篇
化学工业   55篇
金属工艺   5篇
机械仪表   3篇
建筑科学   7篇
能源动力   14篇
轻工业   31篇
水利工程   1篇
石油天然气   1篇
无线电   10篇
一般工业技术   79篇
冶金工业   1948篇
原子能技术   2篇
自动化技术   22篇
  2023年   2篇
  2022年   2篇
  2021年   7篇
  2020年   3篇
  2019年   2篇
  2018年   3篇
  2017年   5篇
  2016年   5篇
  2015年   3篇
  2013年   13篇
  2012年   10篇
  2011年   17篇
  2010年   9篇
  2009年   12篇
  2008年   12篇
  2007年   12篇
  2006年   11篇
  2005年   10篇
  2004年   9篇
  2003年   10篇
  2002年   3篇
  2001年   7篇
  2000年   5篇
  1999年   50篇
  1998年   589篇
  1997年   317篇
  1996年   250篇
  1995年   155篇
  1994年   105篇
  1993年   108篇
  1992年   20篇
  1991年   42篇
  1990年   37篇
  1989年   20篇
  1988年   26篇
  1987年   34篇
  1986年   30篇
  1985年   36篇
  1982年   5篇
  1981年   8篇
  1980年   10篇
  1978年   4篇
  1977年   30篇
  1976年   111篇
  1975年   10篇
  1926年   1篇
  1925年   3篇
  1907年   1篇
  1904年   2篇
  1903年   1篇
排序方式: 共有2184条查询结果,搜索用时 0 毫秒
991.
992.
Graduates of foreign nursing schools are a unique and valuable resource of the U.S. health care delivery system. Due to inadequate communication skills and a lack of cultural enculturation of many foreign nurse graduates (FNGs), some may not reach their full potential as a professional nurse. Agencies who employ FNGs can greatly improve their integration by providing continuing education to enhance communication and cultural enculturation. This model of a communications skills course addresses all aspects of communication: therapeutic, verbal and non-verbal, while integrating a cultural component. Thus, the implementation of this model can enhance foreign nurse graduates' ability to practice in the U.S. health care system.  相似文献   
993.
We describe the presence of a minisatellite sequence that displays length polymorphisms in the fission yeast Schizosaccharomyces pombe. The minisatellite sequence was found to reside within the propeptide region of the vacuolar carboxypeptidase Y gene. The minisatellite sequence, which was found only at a single locus, was mitotically stable and displayed length polymorphisms between the two varieties of S. pombe (S. pombe var. pombe and S. pombe var. malidevorans). The minisatellite sequence, however, appeared to be species specific and was absent in other members of the Schizosaccharomyces genus. This report constitutes the first experimental demonstration of the presence of such sequences in yeasts.  相似文献   
994.
Pseudomonas aeruginosa is an opportunistic pathogen that causes serious and sometimes fatal infections in the compromised host, especially in patients with major trauma or thermal injuries. Exotoxin A (ETA) is the major and most lethal virulence factor produced by this ubiquitous microorganism. In a recent study (H. S. Elzaim, A. K. Chopra, J. W. Peterson, R. Goodheart, and J. P. Heggers, Infect. Immun. 66:2170-2179, 1998), we identified two major epitopes, one within the translocation domain (amino acid [aa] residues 289 to 333) of ETA and another within the enzymatic domain (aa 610 to 638), by using a panel of antipeptide antibodies. Synthetic peptides representing these two epitopes induced ETA-specific antibodies which were able to abrogate the cytotoxic activity of ETA, as measured by incorporation of [3H]leucine into 3T3 fibroblasts. In the present study, these antibodies were tested for the ability to provide protection against ETA and infection with a toxin-producing strain of P. aeruginosa in a mouse model. Antibodies to either of the synthetic peptides conferred protection against ETA. Also, when used for immunization, both peptides induced active immunity to ETA in mice. Antibodies to the peptide representing a region within the enzymatic domain of ETA, in combination with the antibiotic amikacin, enhanced the survival of mice infected with a toxin-producing strain of P. aeruginosa. Thus, antipeptide antibodies specific for ETA might be paired with antibiotic treatment for passive immunization of patients suffering from P. aeruginosa infection.  相似文献   
995.
996.
The analysis of 70 cases of surgical treatment for intraoperative injuries and cicatricial strictures of extrahepatic bile ducts was carried out. In 25 patients surgical procedure was restorative and in 45--reconstructiver. Most common causes of corrective operations were: iatrogenic injuries of extrahepatic bile ducts (14) and cicatricial strictures of hepaticocholedochal duct due to intraoperative trauma (31). The problems of operative technique in performing biliobilio-, hepato-hepatico and hepatico-jejuno-anastomoses are considered. There were three deaths in the early postoperative period: 2 patients died of hepatic failure, pyogenic cholangiogenic intoxication caused by cholangioectasies and intrahepatic abscesses, and 1-due to generalyzed peritonitis caused by acute gastric ulcer perforation. Special attention is paid to the choice of the method of prolonged drainage used in reconstructive as well as in restorative operations.  相似文献   
997.
Leptin is a hormone that regulates food intake, and its receptor (OB-Rb) is expressed primarily in the hypothalamus. Here, it is shown that OB-Rb is also expressed in human vasculature and in primary cultures of human endothelial cells. In vitro and in vivo assays revealed that leptin has angiogenic activity. In vivo, leptin induced neovascularization in corneas from normal rats but not in corneas from fa/fa Zucker rats, which lack functional leptin receptors. These observations indicate that the vascular endothelium is a target for leptin and suggest a physiological mechanism whereby leptin-induced angiogenesis may facilitate increased energy expenditure.  相似文献   
998.
999.
OBJECTIVES: To study the outcome and complications of assisted ventilation in neonates with hyaline membrane disease (HMD). DESIGN: Retrospective study. SETTING: Hospital based. SUBJECTS: Seventy five premature neonates with HMD needing assisted ventilation born over a period of five years. MAIN OUTCOME MEASURES: Survival rate among those ventilated and complications of assisted ventilation. RESULTS: Survival on assisted ventilation improved from initial 22.2% in 1989 to 77.8% in 1993. Of 19 babies weighing between 750-1000 g, 8(42.1%) survived. Twelve of 27 babies (44.4%) with a gestation of less than 28 weeks survived. Survival rates in babies with gestation of more than 33 weeks was 94%. Intraventricular hemorrhage was the leading cause of death in 52% babies. Nosocomial infections were common and occurred in 50.6% of infants on ventilation and accounted for one-third of deaths. Pneumothorax occurred in one-fifth of babies and was responsible for 3 deaths. Pulmonary interstitial emphysems was observed in 6 babies. Six babies developed bronchopulmonary dysplasia while 7 had retinopathy of prematurity. CONCLUSIONS: Outcome of neonates needing assisted ventilation for HMD has shown consistent improvement over the period of study. Nosocomial infections continue to be a major complication of assisted ventilation in neonates.  相似文献   
1000.
PURPOSE: To evaluate the effectiveness of Guglielmi detachable coils (GDCs) filled with collagen threads in the permanent treatment of experimental aneurysms. METHODS: Seventeen side-wall aneurysms were surgically constructed in the canine common carotid artery; six were treated with conventional GDCs and 11 with collagen-filled GDCs. One aneurysms was removed at 1 week, the others were studied by digital subtraction angiography for a period of 8 to 12 weeks. Longitudinal sections of all aneurysms were examined by light microscopy. RESULTS: Angiograms obtained throughout the follow-up period showed no significant difference between aneurysms treated with conventional GDCs and those treated with collagen-filled GDCs. Light microscopy revealed a dense meshwork of newly formed collagen and fibroblasts near the collagen-filled GDCs, whereas a loose cellular meshwork surrounded the conventional GDCs at 8 and 12 weeks after treatment. CONCLUSION: Collagen threads within GDCs do not noticeably improve angiographic treatment of experimental aneurysms; however, these threads did induce local proliferation of fibroblasts and production of collagen within the aneurysmal cavities.  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