全文获取类型
收费全文 | 1664篇 |
免费 | 105篇 |
出版年
2022年 | 10篇 |
2021年 | 17篇 |
2020年 | 9篇 |
2019年 | 17篇 |
2018年 | 22篇 |
2017年 | 22篇 |
2016年 | 26篇 |
2015年 | 58篇 |
2014年 | 61篇 |
2013年 | 87篇 |
2012年 | 98篇 |
2011年 | 87篇 |
2010年 | 78篇 |
2009年 | 71篇 |
2008年 | 115篇 |
2007年 | 102篇 |
2006年 | 89篇 |
2005年 | 86篇 |
2004年 | 95篇 |
2003年 | 92篇 |
2002年 | 93篇 |
2001年 | 33篇 |
2000年 | 36篇 |
1999年 | 26篇 |
1998年 | 18篇 |
1997年 | 20篇 |
1996年 | 12篇 |
1995年 | 18篇 |
1994年 | 19篇 |
1993年 | 17篇 |
1992年 | 22篇 |
1991年 | 17篇 |
1990年 | 28篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1986年 | 14篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 5篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 12篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1966年 | 6篇 |
排序方式: 共有1769条查询结果,搜索用时 15 毫秒
21.
Shoji Machida 《Primates; journal of primatology》1990,31(2):205-211
The vocal behavior of threat calls was investigated in a captive group of Japanese monkeys (Macaca fuscata fuscata). The vocalizations were heard most often when they undertook winner-support during triadic agonistic interactions. The likelihood
of call emission in support of the winner was affected by the attributes of the participants, and not by the types of agonistic
behavior. The calls were emitted by intermediate ranking animals frequently in support of high ranking animals and in support
of females. The calling behavior of winner-supporters appears to advertise the partner and distant group members of their
support for reciprocation in the near future. 相似文献
22.
23.
Yoshihiko Machida 《Ichthyological Research》1990,36(4):507
The online version of the original article can be found at 相似文献
24.
Prosaposin Facilitates Sciatic Nerve Regeneration In Vivo 总被引:3,自引:0,他引:3
Yasunori Kotani Seiji Matsuda Masahiro Sakanaka Keiji Kondoh Shu-ichi Ueno Akira Sano 《Journal of neurochemistry》1996,66(5):2019-2025
Abstract: Prosaposin, a multifunctional protein, is the precursor of saposins, which activate sphingolipid hydrolases. In addition to acting as a precursor for saposins, prosaposin has been shown to rescue hippocampal CA1 neurons from lethal ischemic damage in vivo and to promote neurite extension of neuroblastoma cells in vitro. Here we show that prosaposin, when added to a collagen-filled nerve guide after sciatic nerve transection in guinea pigs, increased dramatically the number of regenerating nerve fibers within the guide. To identify the target neurons of prosaposin during peripheral nerve regeneration, we determined the degree of atrophy and chromatolysis of neurons in the spinal anterior horn and dorsal root ganglia on the prosaposin-treated and untreated side. The effect of prosaposin on large spinal neurons and small neurons of the dorsal root ganglion was more conspicuous. Subsequent immunohistochemistry demonstrated that the atrophy of cholinergic large neurons in the anterior horn is prevented to significant extent by prosaposin treatment. These findings suggest that prosaposin promotes peripheral nerve regeneration by acting on α-motor neurons in the anterior horn and on small sensory neurons in the dorsal root ganglion. The present study raises the possibility of using prosaposin as a tool for the treatment of peripheral nerve injuries. 相似文献
25.
Toshio Ariga Shama Bhat Takashi Kanda Masanaga Yamawaki Tadashi Tai Yasunori Kushi Takeshi Kasama Shizuo Handa Robert K. Yu 《Glycoconjugate journal》1996,13(2):135-145
We analysed the glycolipid composition of glioma cells (N-370 FG cells), which are derived from a culture of transformed human fetal glial cells. The neutral and acidic glycolipid fractions were isolated by column chromatography on DEAE-Sephadex and analysed by high-performance thin-layer chromatography (HPTLC). The neutral glycolipid fraction contained 1.6 µg of lipid-bound glucose/galactose per mg protein and consisted of GlcCer (11.4% of total neutral glycolipids), GalCer (21.5%), LacCer (21.4%), Gb4 (21.1%), and three unknown neutral glycolipids (23%). These unknown glycolipids were characterized as Lewisx (fucosylneolactonorpentaosyl ceramide; Lex), difucosylneolactonorhexaosyl ceramide (dimeric Lex), and neolactonorhexaosyl ceramide (nLc6) by an HPTLC-overlay method for glycolipids using specific mouse anti-glycolipid antibodies against glycolipid and/or liquid-secondary ion (LSI) mass spectrometry. The ganglioside fraction contained 0.6 µg of lipid-bound sialic acid per mg protein with GD1a as the predominant ganglioside species (83% of the total gangliosides) and GM3, GM2, and GM1 as minor components. Trace amounts of sialyl-Lex and the complex type of sialyl-Lex derivatives were also present. Immunocytochemical studies revealed that GD1a and GalCer were primarily localized on the surface of cell bodies. Interestingly, Lex glycolipids and sialyl-Lex were localized not only on the cell bodies but also on short cell processes. Especially, sialyl-Lex glycolipid was located on the tip of fine cellular processes. The unique localization of the Lex glycolipids suggests that they may be involved in cellular differentiation and initiation of cellular growth in this cell line. 相似文献
26.
The reason for failure to initiate fertilization internally was examined in a cottid fish, the elkhorn sculpin, Alcichthys alcicornis which has internal gametic association and external fertilization. While eggs could be activated in calcium free hypertonic media but not be fertilized, fertilization occurred in isotouic media rich in calcium ions. The rate of fertilization was dependent on calcium concentration, and eggs were not fertilized in solutions with a calcium ion concentration of less than 0·57 mmol kg−1 . Calcium ions could be replaced to some extent by magnesium ions, but the former were the more effective in fertilization. Since calcium ion concentration of ovarian fluid of A. alcicornis was 0·41 mmol kg−1 , it was inferred that low calcium concentration in the ovarian fluid was the cause of the failure of A. alcicornis eggs to fertilize internally. 相似文献
27.
Autotrophic picoplankton in southern Lake Baikal: abundance, growth and grazing mortality during summer 总被引:5,自引:0,他引:5
Nagata Toshi; Takai Kenji; Kawanobe Kyoko; Kim Dong-Sup; Nakazato Ryoji; Guselnikova Nina; Bondarenko Nina; Mologawaya Oliga; Kostrnova Tatyana; Drucker Valentine; Satoh Yasuhiro; Watanabe Yasunori 《Journal of plankton research》1994,16(8):945-959
Autotrophic picoplankton were highly abundant during the thermalstratification period in late July in the pelagic area (waterdepth 5001300 m) of southern Lake Baikal; maximum numberswere 2 x 106 cells ml1 in the euphotic zone ({small tilde}15m). Unicellular cyanobacteria generally dominated the picoplanktoncommunity, although unidentified picoplankton that fluorescedred under blue excitation were also abundant (maximum numbers4 x 105 cells ml1) and contributed up to {small tilde}40%of the total autotrophic picoplankton on occasions. Carbon andnitrogen biomasses of autotrophic picoplankton estimated byconversion from biovolumes were 1484 µg C l1and 3.621 µg N l1. These were comparableto or exceeded the biomass of heterotrophic bacteria. Autotropicpicoplankton and bacteria accounted for as much as 33% of paniculateorganic carbon and 81% of nitrogen in the euphotic zone. Measurementsof the photosynthetic uptake of [l4C]bicarbonate and the growthof picoplankton in diluted or size-fractionated waters revealedthat 80% of total primary production was due to picoplankton,and that much of this production was consumed by grazers inthe <20 µ.m cell-size category. These results suggestthat picoplankton-protozoan trophic coupling is important inthe pelagic food web and biogeochemical cycling of Lake Baikalduring summer. 相似文献
28.
Susumu Ikegami Yasunori Ooe Takahiko Shimizu Toshihiko Kasahara Tatsuhiko Tsuruta Masako Kijima Minoru Yoshida Teruhiko Beppu 《Development genes and evolution》1993,202(3):144-151
Summary External application of 10 rig/ml (R)-trichostatin A (TSA), a potent and specific inhibitor of mammalian histone deacetylase, to the embryo of the starfish Asterina pectinifera inhibited development during the early gastrula stage before formation of mesenchyme cells. The TSA-sensitive period was limited to the mid-blastula stage before hatching. The pulse-chase experiment clearly demonstrated that TSA induced an accumulation of acetylated histone species in blastulae through inhibition of historic deacetylation. Similar blockage of development at the early gastrula stage was observed with n-butyrate, which has been known as a weak inhibitor of historic deacetylase. These results suggest an intimate role for historic acetylation-deacetylation equilibria in starfish development.
Correspondence to: S. Ikegami 相似文献
29.
30.
Toyomasu Tomonobu; Yamane Hisakazu; Yamaguchi Isomaro; Murofushi Noboru; Takahashi Nobutaka; Inoue Yasunori 《Plant & cell physiology》1992,33(6):695-701
Four 13-hydroxygibberellins, gibberellin A1 (GA1), 3-epi-GA1,GA19 and GA20 were identified by full-scan GC/MS in extractsof lettuce seedlings (Lactuca sativa L. cv. Grand Rapids). Theresults suggest that the early-13-hydroxylation biosyntheticpathway to GA1 functions in the lettuce seedlings. It was alsofound that GA1 is active per se in the control of hypocotylelongation in lettuce seedlings. To investigate the relationshipbetween control by light of hypocotyl elongation and levelsof endogenous GAs in lettuce, endogenous levels of GAs werequantified by radioimmunoassay in seedlings that had been grownfor 5 days in the dark (5D) and in those that had been grownfor 4 days in the dark and then under white light for 1 day(4D1L). The endogenous level of GA1 in the upper and lower partsof hypocotyls in 5D seedlings was about four times higher thanthat in 4D1L seedlings. The response of explants (hypocotylsegments with cotyledons) from dark-grown seedlings to GA1 isknown to be similar in the dark and under white light when theexplants are treated with inhibitors of the biosynthesis ofGA. Therefore, the above information suggests that the highlevel of GA1 in hypocotyls of dark-grown seedlings is responsiblefor the rapid elongation of hypocotyl, while irradiation bywhite light decreases the endogenous level of GA1 in the hypocotylswith a resultant decrease in the rate of hypocotyl elongation. (Received March 13, 1992; Accepted May 21, 1992) 相似文献