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   3523篇
  免费   407篇
  国内免费   1篇
  2021年   53篇
  2020年   43篇
  2019年   82篇
  2018年   69篇
  2017年   37篇
  2016年   47篇
  2015年   83篇
  2014年   93篇
  2013年   143篇
  2012年   144篇
  2011年   162篇
  2010年   93篇
  2009年   86篇
  2008年   150篇
  2007年   134篇
  2006年   151篇
  2005年   111篇
  2004年   99篇
  2003年   111篇
  2002年   107篇
  2001年   122篇
  2000年   102篇
  1999年   98篇
  1998年   51篇
  1997年   48篇
  1996年   63篇
  1995年   54篇
  1994年   44篇
  1993年   51篇
  1992年   66篇
  1991年   80篇
  1990年   74篇
  1989年   75篇
  1988年   66篇
  1987年   66篇
  1986年   49篇
  1985年   62篇
  1984年   57篇
  1983年   48篇
  1982年   35篇
  1981年   49篇
  1980年   36篇
  1979年   34篇
  1978年   33篇
  1977年   32篇
  1975年   34篇
  1974年   29篇
  1973年   28篇
  1972年   32篇
  1971年   38篇
排序方式: 共有3931条查询结果,搜索用时 31 毫秒
1.
Local administration of phencyclidine (PCP) by pressure ejection elicited a dose-dependent slowing of the spontaneous discharge of cerebellar Purkinje neurons. Ketamine also depressed firing and was much less potent than PCP. Effects of both PCP and ketamine were antagonized by local or parenteral administration of antipsychotic drugs. The similarities between the electrophysiological and behavioral actions of phencyclidine suggest that alterations in neuronal discharge may underlie its psychotomimetic properties.  相似文献   
2.
3.
4.
The in vivo effects of dexamethasone administration on liver and extrahepatic tissue carnitine concentrations were assessed in 48-h-starved rats. In heart and kidney, but not in liver, dexamethasone significantly increased total carnitine concentration. Acute (2.5 h) treatment with 2-tetradecylglycidate (TDG), a specific inhibitor of carnitine palmitoyl transferase 1, not only increased total hepatic carnitine concentrations, but also permitted an effect of dexamethasone (a further increase in hepatic carnitine concentration). The results are discussed in terms of acute (substrate-mediated) and chronic (hormonal) control of carnitine turnover.  相似文献   
5.
We have measured the magnetic circular dichroism of cytochrome c peroxidase and some of its derivatives from 250-350 nm. Comparison of the changes observed on conversion to the catalytic intermediate (cytochrome c peroxidase-I) with spectra obtained from horseradish peroxidase and its derivatives and model compounds of protoheme leads us to the conclusion that the observed changes in the magnetic circular dichroism spectra reflect conversion of the heme to the ferryl state. No evidence was found for modification of tryptophan in cytochrome c peroxidase-I.  相似文献   
6.
7.
An evaluation of methods for studying bone marrow obtained from patients with acute lymphoblastic leukemia indicates that both directly prepared and cultured cells are necessary for complete karyotypic analysis, but that both synchronized and unsynchronized cultures may not be necessary.  相似文献   
8.
9.
A case of chromomycosis in which hyperthermia proved effective is reported. The patient was a 56-year-old male bean curd maker who, without any previous history of minor trauma, developed on the extensor side of the left upper arm an eczematous lesion that underwent gradual radial expansion. The lesion showed a well-defined, 7×10 cm infiltrated erythematous plaque with the central area healed and, at the upper and lower borders, adherent scales and crusts on the surface. Histological examination revealed granulomatous changes in the dermis, as well as sclerotic cells within giant cells and microabscesses. On culturing,Fonsecaea pedrosoi was isolated. The patient was treated with disposable chemical pocket warmers, which were secured over the lesion with a rather tight elastic bandage, so that they kept the affected area warm for 24 hours a day. After a month of such hyperthermic treatment, the erythema and infiltration had decreased considerably, and microscopic examination and culture of the crusts both yielded negative results. Examination of biopsy specimens of the lesion after the third month showed that it had cicatrized. The treatment was stopped after 4 months, and no relapse occurred. We also summarize the published results of local hyperthermic treatment of chromomycosis in Japan.  相似文献   
10.
The chromosomes of two patients with ring 13 (r13) were studied using high-resolution RBG banding of prometaphase cells. The rings of the two patients differ slightly in breakpoints. Cell with multiple single, double-sized rings, quadruple-sized rings, rod- and ring-shaped fragments, and fragments showing varied states of condensation were seen, as were cells monosomic for chromosome 13. The evolution of these cell lines as a result of sister chromatid exchange, nondisjunction, ring breakage, and premature chromosome condensation is discussed. Clinical features of these patients reflect the heterogeneity of phenotype for r13 patients. Each case includes a feature of trisomy 13. The significance of mosaicism of cell lines in patients bearing ring chromosomes is considered with respect to variation in clinical findings.  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