全文获取类型
收费全文 | 2141篇 |
免费 | 109篇 |
国内免费 | 1篇 |
出版年
2022年 | 9篇 |
2021年 | 17篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 27篇 |
2017年 | 27篇 |
2016年 | 32篇 |
2015年 | 73篇 |
2014年 | 75篇 |
2013年 | 132篇 |
2012年 | 124篇 |
2011年 | 136篇 |
2010年 | 76篇 |
2009年 | 87篇 |
2008年 | 144篇 |
2007年 | 138篇 |
2006年 | 113篇 |
2005年 | 134篇 |
2004年 | 133篇 |
2003年 | 137篇 |
2002年 | 147篇 |
2001年 | 32篇 |
2000年 | 24篇 |
1999年 | 35篇 |
1998年 | 37篇 |
1997年 | 27篇 |
1996年 | 15篇 |
1995年 | 22篇 |
1994年 | 21篇 |
1993年 | 19篇 |
1992年 | 29篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 26篇 |
1988年 | 22篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1972年 | 6篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1962年 | 5篇 |
排序方式: 共有2251条查询结果,搜索用时 15 毫秒
41.
42.
Ryoichi Sato Masahiko Kobayashi Hitoshi Watanabe 《Journal of invertebrate pathology》1982,40(2):260-265
Nosema bombycis, two Nosema spp., and a Pleistophora sp. were propagated in the silkworm and the fine structures of their spores were studied. The morphology of the polaroplast, the appearance of the nucleus, and the number of coils in the polar filament differed among the spores of the four species. The spores of the three Nosema species, however, had several identical components; e.g., the polaroplast was made up of two parts, they had two nuclei, and the ribosome arrangement was similar. On the other hand, the spore of Pleistophora sp. had a polaroplast composed of three parts, a single nucleus, and ribosomes arranged around the polar filament. Thus the fine structures of the spore differentiate microsporidan species. 相似文献
43.
Tatsunosuke Nakamura Masahiko Nishikawa Keizo Inoue Shoshichi Nojima Toshiyuki Akiyama Ushio Sankawa 《Chemistry and physics of lipids》1980,26(1):101-110
The effect of the length of the side chain of sterols on their interaction with phosphatidylcholine was studied by measuring the permeability properties of liposomes constituted with sterol analogues with side chains of various lengths. The sensitivities of liposomes constituted with these sterol analogues toward digitonin and polyene antibiotics were also examined.The effects of sterols on phase transition of phosphatidylcholine were examined by measuring their effects on permeability increase due to perturbation of phase equilibrium and by differential scanning calorimetry. An analogue with a short side chain, isopropyl (C-22), had a very similar effect to cholesterol in suppressing the permeability increase, suggesting that the full length of the side chain is not necessary for this effect.The permeability of egg yolk phosphatidylcholine at 42°C was suppressed as much by the analogue C-22 as by cholesterol. Androstene-3-β-ol, an analogue without a side chain, however, had little suppressive effect. Thus it is concluded that the condensing effect of sterol requires a side chain, but not the full length of side chain.Liposomes constituted with analogues having a side chain with more than 5 carbon atoms showed maximum reactivity with a polyene antibiotic, amphotericin B, whereas those constituted with analogues having a side chain with less than 4 carbon atoms showed weaker reactivity. These findings indicate that a side chain with more than 5 carbon atoms is essential for the maximum interaction of liposomes with amphotericin B. Unlike amphotericin B, filipin reacted almost equally well with liposomes containing C-22 and with those containing cholesterol. Thus the chain length of the side chain of sterol is less important for interaction of liposomes with filipin than for their interaction with amphotericin B.Liposomes containing analogues having a side chain with more than 6 carbon atoms showed maximum reactivity with digitonin. Thus for the maximum interaction of liposomes with digitonin, the side chain of sterol should be longer than 6 carbon atoms. 相似文献
44.
45.
Two formerly-uncharacterized subunits of 9 kDa and 14 kDa were found in spinach PSI complex. The 9 kDa subunit was released upon removal of antenna chlorophyll complex, whereas the 14 kDa subunit was tightly bound to the core complex. We determined the N-terminal amino acid sequence of the 9 kDa, and an internal sequence of the 14 kDa subunit after protease treatment, since the N-terminus of the latter protein was blocked. These partial sequences suggested that both subunits are new PSI components. 相似文献
46.
Presomite stage rat embryos were cultured for 45–49 hr with medium containing various adrenergic agonists and antagonists.
-Norepinephrine but not
-norepinephrine (several orders of magnitude less potent than the
-isomer at α-1 adrenergic receptors) resulted in a dose-dependent increase of situs inversus similar to that found for phenylephrine, an α-1 adrenergic agonist. Prazosin, an α-1 adrenergic antagonist, inhibited phenylephrine-induced situs inversus in a dose-dependent manner. Neither dexmedetomidine, an α-2 adrenergic agonist, nor isoproterenol, a β adrenergic agonist, caused situs inversus. These results provide pharmacological evidence that stimulation of α-1 but not of α-2 and β adrenergic receptors modulates the control of left/right sidedness in rat embryos. 相似文献
47.
48.
Intravenous administration of short-chain fatty acid (SCFA), such as propionate, butyrate, valerate and caproate, caused a transient increase in transmural potential difference (p.d.) across the small intestine of rat . There was a sigmoid relationship between the change in the p.d. and the logarithm of the dose of SCFA. The median effective dose of propionate, n-butyrate, n-valerate and n-caproate, which was calculated from the each dose-response curve obtained from the terminal ileum, 1.31, 1.43, 0.83 and 0.81 μmole, respectively. Repeated administrations of the same dose of propionate evoked progressively smaller response. The dose-response curve of propionate was shifted to the left by neostigmine and to the right by atropine, suggesting that the action of SCFA may be mediated by acetylcholine, which was released from a nerve ending. 相似文献
49.
Cartilage-derived factor (CDF) : II. Somatomedin-like action on cultured chondrocytes 总被引:2,自引:0,他引:2
Yukio Kato Yoshio Nomura Mitsuko Tsuji Hiroaki Ohmae Masahiko Kinoshita Shinji Hamamoto Fujio Suzuki 《Experimental cell research》1981,132(2):339-347
Previously, we showed that fetal bovine cartilage contains a polypeptide that stimulates the incorporation of [35S]sulfate into proteoglycans synthesized by rat and rabbit costal chondrocytes in culture. In this paper, we report that the cartilage-derived factor (CDF) increases not only [35S]sulfate incorporation but also [3H]thymidine incorporation into rabbit chondrocytes in monolayer culture. The dose-response curve of CDF stimulation of DNA synthesis was similar in profile to that of CDF stimulation of proteoglycan synthesis. In addition, CDF markedly enhanced [3H]uridine incorporation into rabbit chondrocytes and significantly enhanced [3H]serine incorporation into total protein. These findings indicate that fetal bovine cartilage contains a factor that shows somatomedin-like activity in monolayer cultures of rabbit chondrocytes. 相似文献