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   143篇
  免费   12篇
  155篇
  2023年   1篇
  2022年   2篇
  2021年   1篇
  2020年   5篇
  2016年   2篇
  2015年   5篇
  2014年   5篇
  2013年   8篇
  2012年   18篇
  2011年   6篇
  2010年   3篇
  2009年   5篇
  2008年   3篇
  2007年   10篇
  2006年   8篇
  2005年   3篇
  2004年   1篇
  2003年   3篇
  2002年   4篇
  2001年   2篇
  2000年   3篇
  1999年   5篇
  1998年   4篇
  1997年   1篇
  1996年   1篇
  1995年   2篇
  1994年   2篇
  1992年   3篇
  1989年   1篇
  1987年   3篇
  1986年   1篇
  1984年   1篇
  1983年   4篇
  1982年   2篇
  1981年   1篇
  1979年   6篇
  1978年   2篇
  1977年   4篇
  1976年   2篇
  1974年   2篇
  1973年   1篇
  1972年   1篇
  1970年   2篇
  1969年   1篇
  1968年   1篇
  1965年   1篇
  1958年   1篇
  1943年   1篇
  1932年   1篇
排序方式: 共有155条查询结果,搜索用时 31 毫秒
31.
A panel of monoclonal antibodies was tested immunohistochemically to determine the utility of such reagents in distinguishing among metastatic carcinoma, lymphoma, leukemia and primary brain tumors. The monoclonal antibodies used were: (1) a cocktail comprised of three anti-glial fibrillary acidic protein antibodies (alpha-GFAP); (2) UJ13A, a panneuroectodermal antibody; (3) B72.3, which recognizes a carcinoma-distinctive tumor-associated glycoprotein complex; and (4) 2D1, a pan-leukocyte antibody. Fifty-three specimens (21 cerebrospinal fluids, 1 ventricular fluid, 2 brain cyst fluids, 12 needle washings, 15 imprints, 1 subdural fluid and 1 post-shunt fluid) were obtained from 21 gliomas, 2 meningiomas, 1 pineoblastoma, 11 metastatic tumors, 3 lymphomas, 1 leukemia and 14 cases without tumor. alpha-GFAP stained all 21 gliomas and 5 of 5 cases containing reactive brain fragments. UJ13A had a reactivity pattern similar to that of alpha-GFAP, but also stained the meningiomas, pineoblastoma, oat-cell carcinoma and embryonal rhabdomyosarcoma. B72.3 stained all adenocarcinomas and the large-cell carcinoma. 2D1 stained lymphoma and leukemia, all inflammatory cells and 4 of 12 glioblastomas. Although no single antibody was diagnostic of a specific tumor type, this panel accurately differentiated among most primary brain tumors, metastases, leukemias and lymphomas.  相似文献   
32.
Biosynthesis of jasmonic Acid by several plant species   总被引:36,自引:13,他引:23       下载免费PDF全文
Six plant species metabolized 18O-labeled 12-oxo-cis,cis-10,15-phytodienoic acid (12-oxo-PDA) to short chain cyclic fatty acids. The plant species were corn (Zea mays L.), eggplant (Solanum melongena L.), flax (Linum usitatissimum L.), oat (Avena sativa L.), sunflower (Helianthus annuus L.), and wheat (Triticum aestivum L.). Among the products was jasmonic acid, a natural plant constituent with growth-regulating properties. The pathway is the same as the one recently reported by us for jasmonic acid synthesis in Vicia faba L. pericarp. First, the ring double bond of 12-oxo-PDA is saturated; then β-oxidation enzymes remove six carbons from the carboxyl side chain of the ring. Substrate specificity studies indicated that neither the stereochemistry of the side chain at carbon 13 of 12-oxo-PDA nor the presence of the double bond at carbon 15 was crucial for either enzyme step. The presence of enzymes which convert 12-oxo-PDA to jasmonic acid in several plant species indicates that this may be a general metabolic pathway in plants.  相似文献   
33.
34.
Summary A continuous stirred tank reactor (CSTR) with cell recycle was used to produce lactic acid from glucose usingLactobacillus delbreuckii NRRLB445. A volumetric productivity of 76 gm/1-h was obtained with an effluent concentration of 35 gm/1 lactic acid and a residual glucose concentration of less than 0.02 gm/l.  相似文献   
35.
36.
The perception of pictorial gaze cues was examined in long-tailed macaques (Macaca fascicularis). A computerised object-location task was used to explore whether the monkeys would show faster response time to locate a target when its appearance was preceded with congruent as opposed to incongruent gaze cues. Despite existing evidence that macaques preferentially attend to the eyes in facial images and also visually orient with depicted gaze cues, the monkeys did not show faster response times on congruent trials either in response to schematic or photographic stimuli. These findings coincide with those reported for baboons testing with a similar paradigm in which gaze cues preceded a target identification task [Fagot, J., Deruelle, C., 2002. Perception of pictorial gaze by baboons (Papio papio). J. Exp. Psychol. 28, 298-308]. When tested with either pictorial stimuli or interactants, nonhuman primates readily follow gaze but do not seem to use this mechanism to identify a target object; there seems to be some mismatch in performance between attentional changes and manual responses to gaze cues on ostensibly similar tasks.  相似文献   
37.
The biosynthesis of jasmonic acid: a physiological role for plant lipoxygenase   总被引:30,自引:0,他引:30  
Linolenic acid was converted to a cyclic product, 12-oxo-phytodienoic acid, by lipoxygenase and hydroperoxide cyclase enzymes present in Vicia faba pericarp. Isotope labeling studies in which [U-14C] 12-[180] oxo-phytodienoic acid was incubated with thin sections of pericarp tissue showed that 12-oxo-phytodienoic acid is a biosynthetic precursor to jasmonic acid, a plant growth regulator which promotes senescence. Key enzymes proposed for this pathway are a reductase enzyme which reduces a double bond in the cyclopentenone ring, and beta-oxidation enzymes which remove six carbons from the carboxyl end of the molecule.  相似文献   
38.
39.
40.
Genetic linkage analysis in the laboratory mouse identified chromosomal regions containing genes that contribute to cholesterol accumulation in the liver and plasma. Comparisons between five inbred strains of mice obtained from the Jackson Laboratory (DBA/2, AKR, C57BL/6, SJL, and 129P3) revealed a direct correlation between intestinal cholesterol absorption and susceptibility to diet-induced hypercholesterolemia. This correlation was lost in the F1 generation arising from crosses between high- and low-absorbing strains. Linkage analyses in AKxD recombinant inbred strains and 129xSJL129F1 N2 backcross mice identified four quantitative trait loci (QTL) that influenced Liver cholesterol accumulation (Lcho1-4) and one locus that affected Plasma cholesterol accumulation (Pcho1). These loci map to five chromosomes and, with one exception, are different from the seven QTL identified previously that influence intestinal cholesterol absorption. We conclude that a large number of genes affects the amount of cholesterol absorbed in the small intestine and its accumulation in the liver and plasma of inbred mice.  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