全文获取类型
收费全文 | 1439篇 |
免费 | 76篇 |
国内免费 | 1篇 |
专业分类
1516篇 |
出版年
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 18篇 |
2015年 | 25篇 |
2014年 | 34篇 |
2013年 | 137篇 |
2012年 | 59篇 |
2011年 | 64篇 |
2010年 | 42篇 |
2009年 | 42篇 |
2008年 | 82篇 |
2007年 | 81篇 |
2006年 | 100篇 |
2005年 | 86篇 |
2004年 | 101篇 |
2003年 | 112篇 |
2002年 | 77篇 |
2001年 | 24篇 |
2000年 | 14篇 |
1999年 | 12篇 |
1998年 | 26篇 |
1997年 | 22篇 |
1996年 | 16篇 |
1995年 | 15篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 24篇 |
1991年 | 9篇 |
1990年 | 16篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 18篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 8篇 |
1970年 | 4篇 |
1968年 | 5篇 |
排序方式: 共有1516条查询结果,搜索用时 15 毫秒
91.
Nakazawa M Takenaka S Ueda M Inui H Nakano Y Miyatake K 《Archives of biochemistry and biophysics》2003,411(2):183-188
Pyruvate:NADP(+) oxidoreductase (PNO) is a thiamin pyrophosphate (TPP)-dependent enzyme that plays a central role in the respiratory metabolism of Euglena gracilis, which requires thiamin for growth. When thiamin was depleted in Euglena cells, PNO protein level was greatly reduced, but its mRNA level was barely changed. In addition, a large part of PNO occurred as an apoenzyme lacking TPP in the deficient cells. The PNO protein level increased rapidly, without changes in the mRNA level, after supplementation of thiamin into its deficient cells. In the deficient cells, in contrast to the sufficient ones, a steep decrease in the PNO protein level was induced when the cells were incubated with cycloheximide. Immunofluorescence microscopy indicated that most of the PNO localized in the mitochondria in either the sufficient or the deficient cells. These findings suggest that PNO is readily degraded when TPP is not provided in mitochondria, and consequently the PNO protein level is greatly reduced by thiamin deficiency in E. gracilis. 相似文献
92.
Hasegawa Y Ishida Y Kato K Ijiri R Miyake T Nishimata S Watanabe T Namba I Hayabuchi Y Kigasawa H Tanaka Y 《Acta cytologica》2003,47(4):679-684
BACKGROUND: Pancreatoblastoma (PBL) is a rare neoplasm that generally occurs in the pediatric age group and shows unique histopathology, including squamoid corpuscles that may contain tumor cells with optically clear nuclei (OCN) rich in biotin. In the English-language literature there have been two reports on the cytology of PBL, but neither of them refers to the cytologic features of squamoid corpuscles. CASE: A 3-year-old boy with nausea and general fatigue was referred to our center. Imaging studies showed an approximately 7.5-cm, left-sided abdominal mass and multiple metastases in the lung. The abdominal mass was biopsied, and its histology showed solid cellular nests with occasional acinar differentiation and squamoid corpuscles. Imprint cytology of the biopsied sample displayed cellular epithelial nests with focal acinar structures and foci composed of larger cells with a low nuclear/cytoplasmic ratio. These foci contained a few tumor cells with biotin-rich OCN and were determined to be squamoid corpuscles. CONCLUSION: Detection of occasional squamoid corpuscles with biotin-rich OCN can be useful in making a diagnosis of PBL on cytologic samples. 相似文献
93.
Mannitol-1-phosphate dehydrogenase (MtlD) is required for mannitol and glucitol assimilation in Bacillus subtilis: possible cooperation of mtl and gut operons 下载免费PDF全文
Watanabe S Hamano M Kakeshita H Bunai K Tojo S Yamaguchi H Fujita Y Wong SL Yamane K 《Journal of bacteriology》2003,185(16):4816-4824
94.
95.
96.
Ozaki T Ambe S Minai Y Enomoto S Yatagai F Abe T Yoshida S Makide Y 《Biological trace element research》2001,84(1-3):197-211
Interaction of elements in the course of element uptake by carrot (Daucas carota cv. U.S. harumakigosun) exerted by the addition of elements, such as Rb, Zn, and Al, was investigated. For the purpose of precise evaluation of uptake behavior, the simultaneous determination of absorption of Na, Be, Sr, Mn, Co, Zn, Ce, Pm, and Gd was conducted by the multitracer technique. For root uptakes, Al exhibited its influence on the uptake of essential elements and on the uptake of toxic or unbeneficial ones, presumably as a result of the large electric valency that caused cell membrane disintegrity. On the other hand, Zn as a divalent cation only affected the uptake of essential and beneficial elements. Rubidium, which is a monovalent cation, did not exhibit any effect on the uptake of other ions. Concerning shoot uptakes, inhibition by Zn and Al, but not by Rb, was observed for the uptake of Sr, Mn, Co, and Zn. From the present investigation, it is suggested that there exists an interaction between added ions and the elements taken into plants and that the degree of interaction increases in the increasing order of ionic valency: M+ (Rb), M2+ (Zn), and M3+ (Al). 相似文献
97.
Liposome immunoblotting assay using a substrate-forming precipitate inside immunoliposomes 总被引:1,自引:0,他引:1
A new immunoblotting assay which uses antibody-coupled liposomes containing horseradish peroxidase is proposed. A substrate 4-chloro-1-naphthol permeated through the phospholipid membrane of the antibody-coupled liposomes and formed a colored product precipitating inside the liposomes. The precipitates accumulated in the liposomes and could be detected at the positions where the liposomes coupled with a target in blotted samples. Combination of liposomes with average diameter of 350 nm and a PVDF membrane with a pore size of 450 nm, 0.02 ng of IgM was detected, while the conventional immunoblotting using antibody-HRP conjugates detected 2 ng of IgM. The sensitivity increased about two orders of magnitude by the liposome immunoblotting assay. This liposome immunoblotting assay gives a simple detection method of proteins with a high sensitivity, as well as a high sensitivity Western blotting assay. 相似文献
98.
Noda M Yamashita S Takahashi N Eto K Shen LM Izumi K Daniel S Tsubamoto Y Nemoto T Iino M Kasai H Sharp GW Kadowaki T 《The Journal of biological chemistry》2002,277(44):41817-41826
99.
Regeneration of hippocampal pyramidal neurons after ischemic brain injury by recruitment of endogenous neural progenitors 总被引:129,自引:0,他引:129
Nakatomi H Kuriu T Okabe S Yamamoto S Hatano O Kawahara N Tamura A Kirino T Nakafuku M 《Cell》2002,110(4):429-441
The adult brain is extremely vulnerable to various insults. The recent discovery of neural progenitors in adult mammals, however, raises the possibility of repairing damaged tissue by recruiting their latent regenerative potential. Here we show that activation of endogenous progenitors leads to massive regeneration of hippocampal pyramidal neurons after ischemic brain injury. Endogenous progenitors proliferate in response to ischemia and subsequently migrate into the hippocampus to regenerate new neurons. Intraventricular infusion of growth factors markedly augments these responses, thereby increasing the number of newborn neurons. Our studies suggest that regenerated neurons are integrated into the existing brain circuitry and contribute to ameliorating neurological deficits. These results expand the possibility of novel neuronal cell regeneration therapies for stroke and other neurological diseases. 相似文献