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   796篇
  免费   0篇
  国内免费   3篇
电工技术   6篇
化学工业   3篇
金属工艺   3篇
轻工业   1篇
一般工业技术   1篇
冶金工业   784篇
自动化技术   1篇
  2019年   1篇
  2016年   1篇
  2011年   1篇
  2008年   1篇
  2003年   1篇
  1999年   18篇
  1998年   235篇
  1997年   153篇
  1996年   108篇
  1995年   46篇
  1994年   39篇
  1993年   36篇
  1992年   6篇
  1991年   11篇
  1990年   10篇
  1989年   14篇
  1988年   5篇
  1987年   4篇
  1986年   8篇
  1985年   7篇
  1983年   2篇
  1982年   3篇
  1981年   1篇
  1980年   10篇
  1979年   1篇
  1978年   2篇
  1977年   20篇
  1976年   52篇
  1975年   1篇
  1972年   1篇
  1955年   1篇
排序方式: 共有799条查询结果,搜索用时 0 毫秒
81.
82.
83.
The effect of the neuroprotective kappa opioid agonist CI-977 on glutamate (GLU)-stimulated calcium signaling was studied in individual primary rat cortical neurons. Using laser scanning confocal microscopy and the fluorescent calcium probe fluo-3, both the sustained and biphasic intracellular calcium concentration [Ca2+]i changes induced by GLU (20-40 microM) were altered by CI-977 (25-100 nM), thereby shifting the neuronal population response from unbuffered to buffered patterns of [Ca2+]i flux. This effect was consistent with the previously demonstrated neuroprotective action of CI-977 against glutamate toxicity in vitro. The effect of CI-977 in altering GLU-induced [Ca2+]i signaling was attenuated by naloxone, consistent with a neuroprotective action of CI-977 at opioid receptors, presumably of the kappa subtype.  相似文献   
84.
85.
Our previous study indicated that 5-hydroxytryptamine (5-HT) immunoreactive fiber densities were decreased in specific areas of the brain in alcohol-preferring rats (P) when compared with alcohol-nonpreferring rats (NP). The results of our current study show that there are quantitative and qualitative differences in 5-HT innervation in other selected regions of the forebrains of P rats. The 5-HT fiber density in the brains of young adult P and NP rats was measured by immunocytochemistry and quantitative image analysis. A routine error of two-dimensional quantitation of nerve fiber was addressed and an adjustment was made. The amount of 5-HT fibers was significantly lower in CA4 and fasciola cinereum of the dorsal hippocampus, caudate-putamen, and hypothalamus of the P as compared with NP rats (unpaired Student's t tests). In examining the fiber types, we found that, in the frontal cortical and hippocampal regions, where normally fine 5-HT fibers with small varicosities and thick 5-HT fibers with large varicosities coexist, fewer fine 5-HT fibers were seen in P rats as compared with NP rats. The fine fibers are known to be vulnerable to abusive drugs. These observations indicate that (a) there are quantitative differences in 5-HT innervation or that the 5-HT in some 5-HT fibers is reduced to a level undetectable by immunocytochemistry, and (b) the fine 5-HT fibers are specifically reduced to a greater degree in the selected brain regions of P rats when compared with that of NP rats. The involvement of the 5-HT system in the alcohol abuse is discussed.  相似文献   
86.
The purpose of this article is to deliberate the moral and legal dilemma entailed in the weapon of the labour strike as a pressure tactic on the Israeli Finance Ministry regarding job slots, budgets and, in effect, violating the collective agreement signed by the nurses and impairing patients' treatment, as opposed to refraining from striking and suffering the heavy burden of work, the lack of trained personnel, low wages, and the inability to give patients proper, high quality treatment.  相似文献   
87.
BACKGROUND: The use of kidneys from non-heartbeating donors (NHB) remains controversial. An increased incidence of delayed primary function and primary nonfunction is common. We report a characteristic syndrome of transaminitis and thrombocytopenia after NHB renal transplantation, which may be predictive of graft outcome. METHODS: Two case histories are presented, followed by a retrospective analysis of 38 NHB renal grafts performed at Guy's Hospital from 1988 to 1994. Changes in alanine aminotransferase (ALT) and platelet count were compared between recipients of kidneys from NHB and heartbeating donors (HB). To control for possible effects of antilymphocyte globulin (ALG), two matched control groups receiving HB kidneys with (n=32) and without (n=32) ALG were also compared. RESULTS: ALT was elevated in 32 of 38 (84%) of NHB recipients and 19 of 64 (30%) controls (P<0.001). Mean peak ALT was 172+/-20 U/L in NHB and 42+/-6 U/L in HB kidneys (P<0.001). Use of ALG did not influence mean peak ALT. Elevated ALT predicted impaired graft function (P<0.02) and was associated with an increased length of delayed primary function (P<0.001) and risk of transplant nephrectomy (P<0.05). Thrombocytopenia (<100 x 10(9) cells/L) occurred in 18 of 38 (47%) NHB recipients and in 20 of 64 (31%) controls (P<0.05). Mean nadir platelet count (x 10(9) cells/L) was 113+/-10 in NHB, 128+/-9 in HB with ALG, and 164+/-9 in HB without ALG (both P<0.05 vs. NHB). Patients who underwent graft nephrectomy (n=9) had a disproportionate fall in platelet count (mean nadir, 80+/-11 x 10(9) cells/L; P<0.05). CONCLUSIONS: Transaminitis and thrombocytopenia occur commonly after NHB kidney transplantation and are predictive of graft outcome. Recognition of these changes may assist the early management of NHB renal recipients, and also reduce investigation of "anomalous" results in this setting.  相似文献   
88.
Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time and the ultimate compressive strength. Three cement formulations were tested. The previously developed Biocement H was made of a powder containing alpha-tertiary calcium phosphate and precipitated hydroxyapatite. Biocement B2 powder was made by adding some CaCO3 to Biocement H, whereas Biocement B1 was made by adding some CaCO3 but with simultaneous adjustment of the amount of precipitated hydroxyapatite.The liquid/ powder ratio of the cement paste and the accelerator concentrations (percentage Na2HPO4) in cement liquid were varied. For Biocement H there was no combination of L/P ratio and percentage Na2HPO4 for which all clinical requirements were satisfied. However, there was an area of full compliance for Biocements B1 and B2, of which that for B1 was the largest. Therefore, Biocement B1 may be applied in clinical situations as those in orthopaedics, plastic and reconstructive surgery and oral and maxillofacial surgery, even when early contact with blood is inevitable.  相似文献   
89.
90.
The sensitivity of the single intradermal comparative tuberculin test, as applied in the Republic of Ireland, was estimated in 353 cattle with tuberculous lesions. These cattle had been removed from 47 herds which were depopulated owing to chronic or extensive infection with Mycobacterium bovis. The test had a sensitivity of 90.9 per cent, because 321 (90.9 per cent) of the 353 cattle with tuberculous lesions gave a positive or inconclusive result, and 32 gave a negative result. These 32 negative cattle came from 17 (36 per cent) of the 47 depopulated herds.  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