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   2009篇
  免费   136篇
  2023年   4篇
  2022年   10篇
  2021年   20篇
  2020年   8篇
  2019年   20篇
  2018年   29篇
  2017年   27篇
  2016年   38篇
  2015年   51篇
  2014年   74篇
  2013年   157篇
  2012年   108篇
  2011年   123篇
  2010年   66篇
  2009年   74篇
  2008年   114篇
  2007年   130篇
  2006年   100篇
  2005年   96篇
  2004年   118篇
  2003年   105篇
  2002年   130篇
  2001年   27篇
  2000年   46篇
  1999年   45篇
  1998年   36篇
  1997年   26篇
  1996年   21篇
  1995年   24篇
  1994年   14篇
  1993年   20篇
  1992年   30篇
  1991年   23篇
  1990年   19篇
  1989年   20篇
  1988年   26篇
  1987年   28篇
  1986年   18篇
  1985年   14篇
  1984年   10篇
  1983年   16篇
  1982年   16篇
  1981年   6篇
  1980年   5篇
  1979年   6篇
  1978年   5篇
  1977年   8篇
  1975年   3篇
  1974年   8篇
  1973年   7篇
排序方式: 共有2145条查询结果,搜索用时 953 毫秒
141.
Surgical stress is difficult to evaluate quantitatively. It has been reported that mitochondrial membrane potential (delta psi(m)) in the peripheral blood lymphocytes (PBLs) is decreased by surgical stress. Thioredoxin (TRX), a small protein with redox-active dithiol/disulfide in the active site, is induced by a variety of oxidative stresses and secreted from the cells. Accumulating evidence shows that plasma levels of TRX are elevated in oxidative stress-associated disorders. In the present study, we examined plasma levels of TRX in cases undergoing operations for gastrointestinal cancer. Plasma levels of TRX were significantly elevated on the first postoperative day compared with the pre-operative levels. The changes in the plasma TRX levels tended to show an inverse relationship with the changes in delta psi(m) in PBLs, which shows a significant decrease caused by surgical stress. Plasma TRX levels as well as delta psi(m) in PBLs are valuable markers to evaluate surgical stress.  相似文献   
142.
The monogenean Pseudodactylogyrus kamegaii sp. n. is described, based on specimens collected from the gills of wild Japanese eel Anguilla japonica caught in Chiba Prefecture, Japan. This species is the most similar to P. anguillae (Yin and Sproston, 1948), but different in the shape and measurements of the male copulatory organ, vagina and marginal hook. This new species was collected from the eel in brackish waters, while P. anguillae and P. bini, the other known pseudodactylogyrids of Japanese eel, have been recorded only in fresh waters.  相似文献   
143.
We examined whether interleukin (IL)-6 exerts the stimulatory effects on the secretion of histamine from human mast cells triggered by crosslinking of the high affinity IgE receptor (FcepsilonRI) with IgE and anti-IgE. As target cells, we used peripheral blood-derived cultured mast cells grown with SCF, because they were superior in FcepsilonRIalpha expression to cord blood-derived mast cells. Incubation with SCF+IL-6 for 1 week increased the IgE-dependent release as well as intracellular content of histamine in the cultured mast cells, as compared with the values obtained by incubation with SCF alone. The magnitude of these increases was higher than that for priming with SCF+IL-4. A striking difference was also found in the expression of FcepsilonRIalpha between the two-factor combinations. The addition of IL-6 during FcepsilonRI crosslinking with IgE/anti-IgE in the presence of SCF did not influence histamine secretion. When SCF, IL-6 and IL-4 were used together, a further increase was observed in the anti-IgE-dependent liberation of histamine from the cultured mast cells, compared with the two-factor combinations. These results suggest that IL-6 functions as a secretagogue for the inflammatory mediator of human mast cells in the presence of SCF.  相似文献   
144.
145.
Endoscopic eyebrow lift was performed on 51 patients presenting with eyebrow ptosis due to facial paralysis. The resulting anthropometric measurements of eyebrow position were analyzed statistically to evaluate the effectiveness of this method. When preoperative eyebrow differences between the paralyzed and nonparalyzed sides were measured, the average difference at midpoint was 4.4 mm, and at the highest point, 4.6 mm. When the same points were measured postoperatively, the average difference at midpoint was 2.4 mm, and at the highest point, 2.3 mm. The difference in eyebrow height between the paralyzed and nonparalyzed sides correlated positively with age, both preoperatively and postoperatively. However, differences between preoperative and postoperative eyebrow height (which reflects the effectiveness of endoscopic eyebrow lift) at the highest point did not correlate with age and at the midpoint displayed a slightly negative correlation with age. These results suggest that endoscopic eyebrow lift is effective among young patients whose eyebrow ptosis is minor and is relatively ineffective among elderly patients whose eyebrow ptosis is severe. The conventional method of juxta-brow excision is indicated for elderly patients, for whom the operative scar is almost inconspicuous.  相似文献   
146.
From the polar portion of the methanolic extract of cumin (fruit of Cuminum cyminum L.), two sesquiterpenoid glucosides, cuminoside A and B, and two alkyl glycosides were isolated together with five known compounds. Their structures were established as (1S,5S,6S,10S)-10-hydroxyguaia-3,7(11)-dien-12,6-olide beta-D-glucopyranoside, (1R,5R,6S,7S,9S,10R,11R)-1,9-dihydroxyeudesm-3-en-12,6-olide 9-O-beta-D-glucopyranoside, methyl beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside and ethane-1,2-diol 1-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside, respectively.  相似文献   
147.
148.
Eight glycosides of 2-C-methyl-D-erythritol (1) were isolated from the fruit of anise, and their structures were clarified as 1-O-beta-D-glucopyranoside, 3-O-beta-D-glucopyranoside, 4-O-beta-D-glucopyranoside, 1-O-beta-D-fructofuranoside, 3-O-beta-D-fructofuranoside, 4-O-beta-D-fructofuranoside, 1-O-beta-D-(6-O-4-hydroxybenzoyl)-glucopyranoside and 1-O-beta-D-(6-O-4-methoxybenzoyl)-glucopyranoside of 2-C-methyl-D-erythritol (2-9), respectively. Furthermore, 2 and 4 were isolated from the fruit of coriander, and 2, 3 and 4 were isolated from the fruit of cumin. Though the phosphate of 1 was known to be one of the first precursors of isoprenoids in the non-mevalonate pathway, and 1 is considered to be a common constituent in Umbelliferous plants, the glycosides of 1 are found for the first time.  相似文献   
149.
150.
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