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   4910篇
  免费   89篇
  国内免费   1篇
电工技术   19篇
综合类   3篇
化学工业   220篇
金属工艺   28篇
机械仪表   94篇
建筑科学   47篇
矿业工程   3篇
能源动力   40篇
轻工业   123篇
水利工程   7篇
石油天然气   3篇
无线电   171篇
一般工业技术   220篇
冶金工业   3794篇
原子能技术   7篇
自动化技术   221篇
  2023年   16篇
  2022年   31篇
  2021年   50篇
  2020年   23篇
  2019年   39篇
  2018年   44篇
  2017年   40篇
  2016年   69篇
  2015年   41篇
  2014年   54篇
  2013年   101篇
  2012年   59篇
  2011年   73篇
  2010年   50篇
  2009年   74篇
  2008年   50篇
  2007年   42篇
  2006年   53篇
  2005年   59篇
  2004年   42篇
  2003年   36篇
  2002年   28篇
  2001年   21篇
  2000年   14篇
  1999年   147篇
  1998年   1315篇
  1997年   716篇
  1996年   433篇
  1995年   255篇
  1994年   197篇
  1993年   266篇
  1992年   42篇
  1991年   51篇
  1990年   43篇
  1989年   31篇
  1988年   28篇
  1987年   45篇
  1986年   28篇
  1985年   27篇
  1983年   9篇
  1982年   13篇
  1981年   17篇
  1980年   18篇
  1979年   4篇
  1978年   5篇
  1977年   66篇
  1976年   118篇
  1975年   5篇
  1972年   2篇
  1965年   2篇
排序方式: 共有5000条查询结果,搜索用时 46 毫秒
61.
62.
A 10-year-old, previously healthy female presented to the emergency department via emergency medical service transport, with her tongue tightly entrapped inside a glass bottle (9 oz, Yoohoo brand of chocolate drink). The tongue was massively edematous and ecchymotic due to impaired venous return from constriction by the neck of the bottle. After repeated attempts at mechanically reducing the tongue out of the bottle, a professional glazier was contacted, who was able to remove the bottle in the operating room with a steel glass cutter. Needle evacuation of a small hematoma was then performed to decrease the pressure ischemia to the tongue, which began to improve quickly.  相似文献   
63.
64.
65.
A simple commercially available compression device allowed intermittent ultrasound scanning of the compression site during compression repair of a femoral artery pseudoaneurysm in six patients. All six of the pseudoaneurysms (five superficial femoral and one common femoral) were compressed without compression of the underlying vessels. The procedure was successful in four of the six patients, without complications. Use of this device may decrease operator fatigue during compression repair of pseudoaneurysm.  相似文献   
66.
67.
Molecular cloning of a novel melanocortin receptor   总被引:2,自引:0,他引:2  
Using the technique of the polymerase chain reaction primed with oligonucleotides based on the homologous transmembrane regions of seven transmembrane G protein-linked receptors, we isolated three full-length human genes that encode a novel subgroup of this receptor family. Recently, two of these receptors were identified as specific for alpha-melanocyte-stimulating hormone (alpha-MSH) and adrenocorticotropic hormone. We report the molecular cloning and pharmacologic characterization of a third member of this subgroup. The gene for this receptor encodes a protein of 361 amino acids in length. Its pharmacology characterizes it as an MSH receptor specific to the heptapeptide core common to adrenocorticotropic hormone and alpha-, beta-, and gamma-MSH. By Northern blot hybridization and polymerase chain reaction, it is expressed in brain, placental, and gut tissues but not in melanoma cells or in the adrenal gland. These findings may yield insight into the physiology of peptides derived from pro-opiomelanocortin post-translational processing.  相似文献   
68.
Exploring the antigenic and genetic diversities of Babesia ovata, we obtained several field isolates from grazing cattle in the Okushiri island, Japan. Parasite isolation was greatly facilitated by using bovine red blood cell-substituted SCID mice (Bo-RBC-SCID mice), into which the blood samples of the cattle were inoculated. Isolates from different individuals within a herd of cattle were compared in immunoblot analysis with an anti-B. ovata serum and also in Southern blot analysis with a probe for the small subunit ribosomal RNA gene. In both analyses, the isolates exhibited banding patterns that were significantly different from each other. We were also able to obtain a series of parasite isolates from a single cow in different seasons of a nine months period, including winter when active vector ticks were not in the field environment. Different seasonal isolates showed different banding patterns in both immunoblot and Southern blot analyses. By contrast, these analyses detected little difference among the parasites that had been passed various times in Bo-RBC-SCID mice, where no specific immune responses should be generated. These results indicate that individual animals within a herd of cattle were infected with antigenically and genetically diversified populations of B. ovata, and that the parasites could persistently infect a single animal with dynamic change in their predominant subpopulations.  相似文献   
69.
A dietary treatment plan that considers both quality-of-care and quality-of-life issues is most beneficial for elderly patients. Diabetes can be successfully managed in most elderly patients with a liberalized diet that is low in simple sugars and includes variety and moderation in food choices. Although dietary management in osteoporosis may be most compelling in its preventive capacity, clinicians treating elderly patients with osteoporosis are well advised to consider supplementation of the diet with calcium and vitamin D in amounts equal to the RDAs if patients are unable to consume adequate calcium and vitamin D and if exposure to sunlight is minimal. Encouraging calcium intake, moderate exercise, maintenance of desirable body weight, and avoidance of laxative and antacid abuse with patients throughout the life cycle is appropriate preventive advice. The elderly renal failure patient may benefit from dietary modification of protein, potassium, sodium, fluid, vitamins, and minerals when complications associated with these nutrients are present. Because clinicians treat significant numbers of elderly diabetic, osteoporotic, and renal failure patients, and because many skilled nursing facilities are developing specialty and rehabilitation units for such high-acuity level patients, the clinician is well advised to know how to maximize quality of care and quality of life for these patients through appropriate dietary intervention.  相似文献   
70.
Purkinje cell toxicity is one of the characteristic features of the Gordon phenomenon, a syndrome manifested by ataxia, muscular rigidity, paralysis, and tremor that may lead to death (Gordon, 1933). Two members of the RNase superfamily found in humans, EDN (eosinophil-derived neurotoxin) and ECP (eosinophil cationic protein), cause the Gordon phenomenon when injected intraventricularly into guinea pigs or rabbits. We have found that another member of the RNase superfamily, an antitumor protein called onconase, isolated from Rana pipiens oocytes and early embryos, will also cause the Gordon phenomenon when injected into the cerebrospinal fluid of guinea pigs at a dose similar to that of EDN (LD50, 3-4 micrograms). Neurologic abnormalities of onconase-treated animals were indistinguishable from those of EDN-treated animals, and histology showed dramatic Purkinje cell loss in the brains of onconase-treated animals. The neurotoxic activity of onconase correlates with ribonuclease activity. Onconase modified by iodoacetic acid to eliminate 70% and 98% of the ribonuclease activity of the native enzyme displays a similar decrease in ability to cause the Gordon phenomenon. In contrast, the homologous bovine pancreatic RNase A injected intraventricularly at a dose 5000 times greater than the LD50 dose of EDN or onconase is not toxic and does not cause the Gordon phenomenon. A comparison of the RNase activities of EDN, onconase, and bovine pancreatic RNase A using three pancreatic RNA substrates demonstrates that onconase is orders of magnitude less active enzymatically than EDN and RNase A. Thus, another member of the RNase superfamily in addition to EDN and ECP can cause the Gordon phenomenon.(ABSTRACT TRUNCATED AT 250 WORDS)  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