全文获取类型
收费全文 | 836篇 |
免费 | 42篇 |
出版年
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 13篇 |
2018年 | 16篇 |
2017年 | 7篇 |
2016年 | 26篇 |
2015年 | 40篇 |
2014年 | 44篇 |
2013年 | 39篇 |
2012年 | 66篇 |
2011年 | 71篇 |
2010年 | 33篇 |
2009年 | 29篇 |
2008年 | 44篇 |
2007年 | 48篇 |
2006年 | 42篇 |
2005年 | 57篇 |
2004年 | 45篇 |
2003年 | 50篇 |
2002年 | 47篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 13篇 |
1997年 | 3篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有878条查询结果,搜索用时 171 毫秒
871.
Isamu Murakoshi Kyoko Fukuchi Joju Haginiwa Shigeru Ohmiya Hirotaka Otomasu 《Phytochemistry》1977,16(9):1460-1461
A new lupin alkaloid, N-(3,-oxobutyl)cytisine, was isolated from the aerial parts of Echinosophora koreensis. Its structure was determined by s 相似文献
872.
Ayumu Yamashita Yuki Sakai Takashi Yamada Noriaki Yahata Akira Kunimatsu Naohiro Okada Takashi Itahashi Ryuichiro Hashimoto Hiroto Mizuta Naho Ichikawa Masahiro Takamura Go Okada Hirotaka Yamagata Kenichiro Harada Koji Matsuo Saori C. Tanaka Mitsuo Kawato Kiyoto Kasai Nobumasa Kato Hidehiko Takahashi Yasumasa Okamoto Okito Yamashita Hiroshi Imamizu 《PLoS biology》2020,18(12)
Many studies have highlighted the difficulty inherent to the clinical application of fundamental neuroscience knowledge based on machine learning techniques. It is difficult to generalize machine learning brain markers to the data acquired from independent imaging sites, mainly due to large site differences in functional magnetic resonance imaging. We address the difficulty of finding a generalizable marker of major depressive disorder (MDD) that would distinguish patients from healthy controls based on resting-state functional connectivity patterns. For the discovery dataset with 713 participants from 4 imaging sites, we removed site differences using our recently developed harmonization method and developed a machine learning MDD classifier. The classifier achieved an approximately 70% generalization accuracy for an independent validation dataset with 521 participants from 5 different imaging sites. The successful generalization to a perfectly independent dataset acquired from multiple imaging sites is novel and ensures scientific reproducibility and clinical applicability.Biomarkers for psychiatric disorders based on neuroimaging data have yet to be put to practical use. This study overcomes the problems of inter-site differences in fMRI data by using a novel harmonization method, thereby successfully constructing a generalizable brain network marker of major depressive disorder across multiple imaging sites. 相似文献
873.
Chiroptical materials have received much attention in diverse fields for applications such as displays, sensors, smart memory devices, and catalysis. Here, we develop a simple fabrication method for polymer films with tunable chiroptical properties using small amounts of self-assembling fluorescent dye as an additive. Both the circular dichroism and circularly polarized luminescence signals of the film can be tuned between positive and negative values by thermal treatment. The chiroptical properties can be varied by slight changes in the orientation of chiral pyrene moieties in self-assembled nanofibril networks. 相似文献
874.
The levels of hepatic fatty acid synthesizing enzymes, acetyl-CoA carboxylase and fatty acid synthetase, are lowered to about one-tenth of the controls in hypophysectomized animals, whereas the lung enzymes decrease by only 25–30%. Administration of 3,5,3′-l-triiodothyronine to the hypophysectomized animals returns the hepatic and lung enzyme activities to the control values. Optimum levels are achieved at a dose of about 150 μg/100 g body wt and 3–4 days after triiodothyronine administration. The triiodothyronine response can be reduced by 80% with actinomycin-D or cycloheximide but not with hydrocortisone hemisuccinate. Antibody-antigen titrations and measurements of the rate of synthesis of fatty acid synthetase are indicative of increased synthesis of fatty acid synthetase and not of activation of the preexisting inactive species. These measurements provide evidence for the involvement of hormones other than insulin in the control of synthesis of fatty acid synthesizing enzymes. 相似文献
875.
In vitro exposure to human serum albumin (HSA) of splenic lymphocytes from mice sensitized for delayed-type hypersensitivity (DTH) against HSA resulted in the release of substances that could induce a footpad inflammatory reaction with a maximum 6 hr after injection into normal mice. The substances were fractionated mainly in a molecular weight range of 30,000 to 70,000 daltons on Sephadex G-200. The ability of sensitized lymphocytes to produce the substances was dependent on T cells, was antigen specific, and correlated well with the ability of the lymphocytes to mediate DTH reactions. Moreover, the substances were produced efficiently by the DTH effector cell population generated in the in vitro culture system and also by the effector cell-enriched fractions on discontinuous bovine serum albumin gradients. These results suggest that the substances are produced by DTH-effector cells. 相似文献
876.
Isamu Murakoshi Eiji Kidoguchi Mohammad Ikram Mohammad Israr Nusrat Shafi Joju Haginiwa Shigeru Ohmiya Hirotaka Otomasu 《Phytochemistry》1982,21(6):1313-1315
The major alkaloids of Sophora mollis are (+)-sparteine and (?)-cytisine, and the minor ones are also of the sparteine-type (lupanine and 5,6-deh 相似文献
877.
Isamu Murakoshi Eiji Kidoguchi Joju Haginiwa Shigeru Ohmiya Kimio Higashiyama Hirotaka Otomasu 《Phytochemistry》1982,21(9):2379-2384
Two new lupin alkaloids, isokuraramine and (?)-7, 11-dihydromatrine, were isolated from the fresh flowers of Sophora flavescens along with 16 kno 相似文献
878.