全文获取类型
收费全文 | 320篇 |
免费 | 12篇 |
出版年
2018年 | 10篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 33篇 |
2012年 | 10篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 3篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有332条查询结果,搜索用时 534 毫秒
51.
Discrimination of Porphyra species based on small subunit ribosomal RNA gene sequence 总被引:2,自引:0,他引:2
M. Kunimoto H. Kito Y. Yamamoto D.P. Cheney Y. Kaminishi Y. Mizukami 《Journal of applied phycology》1999,11(2):203-209
The complete nucleotide sequences of ssu rRNA genes were determined for nine species of Porphyra. Ssu rRNA gene structure
was classified into four types by the presence and absence of intron(s). Gene structure even differed within the same species.
Exon nucleotide sequences were identical within the same species, but differed among species. Seventeen species of Porphyra
were discriminated by comparing the sequences of these diversified regions, using the results of this study and previous studies.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
52.
Yamamoto T Niwa S Ohno S Tokumasu M Masuzawa Y Nakanishi C Nakajo A Onishi T Koganei H Fujita S Takeda T Kito M Ono Y Saitou Y Takahara A Iwata S Shoji M 《Bioorganic & medicinal chemistry letters》2008,18(17):4813-4816
In order to find an injectable and selective N-type calcium channel blocker, we have performed the structure–activity relationship (SAR) study on the 2-, 5-, and 6-position of 1,4-dihydropyridine-3-carboxylate derivative APJ2708 (2), which is a derivative of Cilnidipine and has L/N-type calcium channel dual inhibitory activities. As a consequence of the optimization, 6-dimethylacetal derivative 7 was found to have an effective inhibitory activity against N-type calcium channels with more than 170-fold lower activity for L-type channel compared to that of APJ2708. 相似文献
53.
Imamura M Kato N Yoshioka M Okada H Iwamaru Y Shimizu Y Mohri S Yokoyama T Murayama Y 《Journal of virology》2011,85(6):2582-2588
The pathogenic isoform (PrP(Sc)) of the host-encoded cellular prion protein (PrP(C)) is considered to be an infectious agent of transmissible spongiform encephalopathy (TSE). The detailed mechanism by which the PrP(Sc) seed catalyzes the structural conversion of endogenous PrP(C) into nascent PrP(Sc) in vivo still remains unclear. Recent studies reveal that bacterially derived recombinant PrP (recPrP) can be used as a substrate for the in vitro generation of protease-resistant recPrP (recPrP(res)) by protein-misfolding cyclic amplification (PMCA). These findings imply that PrP modifications with a glycosylphosphatidylinositol (GPI) anchor and asparagine (N)-linked glycosylation are not necessary for the amplification and generation of recPrP(Sc) by PMCA. However, the biological properties of PrP(Sc) obtained by in vivo transmission of recPrP(res) are unique or different from those of PrP(Sc) used as the seed, indicating that the mechanisms mediated by these posttranslational modifications possibly participate in reproductive propagation of PrP(Sc). In the present study, using baculovirus-derived recombinant PrP (Bac-PrP), we demonstrated that Bac-PrP is useful as a PrP(C) substrate for amplification of the mouse scrapie prion strain Chandler, and PrP(Sc) that accumulated in mice inoculated with Bac-PrP(res) had biochemical and pathological properties very similar to those of the PrP(Sc) seed. Since Bac-PrP modified with a GPI anchor and brain homogenate of Prnp knockout mice were both required to generate Bac-PrP(res), the interaction of GPI-anchored PrP with factors in brain homogenates is essential for reproductive propagation of PrP(Sc). Therefore, the Bac-PMCA technique appears to be extremely beneficial for the comprehensive understanding of the GPI anchor-mediated stimulation pathway. 相似文献
54.
Keiji Uchiyama Hironori Miyata Masashi Yano Yoshitaka Yamaguchi Morikazu Imamura Naomi Muramatsu Nandita Rani Das Junji Chida Hideyuki Hara Suehiro Sakaguchi 《PloS one》2014,9(10)
Prion infection induces conformational conversion of the normal prion protein PrPC, into the pathogenic isoform PrPSc, in prion diseases. It has been shown that PrP-knockout (Prnp0/0) mice transgenically reconstituted with a mouse-hamster chimeric PrP lacking N-terminal residues 23-88, or Tg(MHM2Δ23-88)/Prnp0/0 mice, neither developed the disease nor accumulated MHM2ScΔ23-88 in their brains after inoculation with RML prions. In contrast, RML-inoculated Tg(MHM2Δ23-88)/Prnp0/+ mice developed the disease with abundant accumulation of MHM2ScΔ23-88 in their brains. These results indicate that MHM2Δ23-88 itself might either lose or greatly reduce the converting capacity to MHM2ScΔ23-88, and that the co-expressing wild-type PrPC can stimulate the conversion of MHM2Δ23-88 to MHM2ScΔ23-88 in trans. In the present study, we confirmed that Tg(MHM2Δ23-88)/Prnp0/0 mice remained resistant to RML prions for up to 730 days after inoculation. However, we found that Tg(MHM2Δ23-88)/Prnp0/0 mice were susceptible to 22L prions, developing the disease with prolonged incubation times and accumulating MHM2ScΔ23-88 in their brains. We also found accelerated conversion of MHM2Δ23-88 into MHM2ScΔ23-88 in the brains of RML- and 22L-inoculated Tg(MHM2Δ23-88)/Prnp0/+ mice. However, wild-type PrPSc accumulated less in the brains of these inoculated Tg(MHM2Δ23-88)/Prnp0/+ mice, compared with RML- and 22L-inoculated Prnp0/+ mice. These results show that MHM2Δ23-88 itself can convert into MHM2ScΔ23-88 without the help of the trans-acting PrPC, and that, irrespective of prion strains inoculated, the co-expressing wild-type PrPC stimulates the conversion of MHM2Δ23-88 into MHM2ScΔ23-88, but to the contrary, the co-expressing MHM2Δ23-88 disturbs the conversion of wild-type PrPC into PrPSc. 相似文献
55.
56.
In this study, we have investigated effects of volatile anesthetics on absorption spectra, proton pumping activity and decay of photointermediate M of bacteriorhodopsin (bR) in differently aggregated states. Anesthetics used in this study are ether-type general anesthetics; enflurane and sevoflurane. The observed effects on bR depend not only on variety or concentration of anesthetics but also strongly on the aggregation state of bR molecules in the membrane. In purple membrane (PM), bR having maximum light absorption at 567 nm (bR567) is formed in the presence of sevoflurane or a small amount of enflurane, while a species absorbing maximally at 480 nm (bR480) is formed upon the addition of large amounts of enflurane. X-ray diffraction studies show that the former species maintains crystallinity of PM, but the latter does not. In reconstituted vesicles where bR molecules exist as monomer, even sevoflurane forms bR480. Flash photolysis experiments show that bR567 contains a shorter-lived M intermediate absorbing maximally at 412 nm in the photoreaction cycle than bR does and that bR480 contains at least two long-lived M intermediates which seem to absorb maximally near and at lower than 380 nm. The measurements of light-induced pH changes of the whole cells and of the reconstituted vesicles in the presence of the anesthetics indicate that bR567 has a enhanced proton pumping efficiency, while bR480 has a quite low or no activity. No significant difference was observed in the anesthetic action between two inversely pumping vesicles. These observations suggest that on the formation of bR480, anesthetics enter into the membrane and affect the protein-lipid interaction. 相似文献
57.
Adaptation of a deep-sea cephalopod to the photic environment. Evidence for three visual pigments
下载免费PDF全文
![点击此处可从《The Journal of general physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Watasenia scintillans, a bioluminescent deep-sea squid, has a specially developed eye with a large open pupil and three visual pigments. Photoreceptor cells (outer segment: 476 micron; inner segment: 99 micron) were long in the small area of the ventral retina receiving downwelling light, whereas they were short (outer segment: 207 micron; inner segment: 44 micron) in the other regions of the retina. The short photoreceptor cells contained the visual pigment with retinal (lambda max approximately 484 nm), probably for the purpose of adapting to their environmental light. The outer segment of the long photoreceptor cells consisted of two strata, a pinkish proximal area and a yellow distal area. The visual pigment with 3-dehydroretinal (lambda max approximately 500 nm) was located in the pinkish proximal area, giving high sensitivity at longer wavelengths. A newly found pigment (lambda max approximately 471 nm) was in the yellow distal area. The small area of the ventral retina containing two visual pigments is thought to have a high and broad spectral sensitivity, which is useful for distinguishing the bioluminescence of squids of the same species in their environmental downwelling light. These findings were obtained by partial bleaching of the extracted pigment from various areas of the retina and by high-performance liquid chromatographic analysis of the chromophore, complemented by microscopic observations. 相似文献
58.
N. Kitamoto M. Go T. Shibayama T. Kimura Y. Kito K. Ohmiya N. Tsukagoshi 《Applied microbiology and biotechnology》1996,46(5-6):538-544
Two endo-1,4-β-glucanase genes, designated celA and celB, from a shoyu koji mold Aspergillus oryzae KBN616, were cloned and characterized. The celA gene comprised 877 bp with two introns. The CelA protein consisted of 239 amino acids and was assigned to the cellulase family
H. The celB gene comprised 1248 bp with no introns. The CelB protein consisted of 416 amino acids and was assigned to the cellulase family
C. Both genes were overexpressed under the promoter of the A. oryzae taka-amylase A gene for purification and enzymatic characterization of CelA and CelB. CelA had a molecular mass of 31 kDa,
a pH optimum of 5.0 and temperature optimum of 55 °C, whereas CelB had a molecular mass of 53 kDa, a pH optimum of 4.0 and
temperature optimum of 45 °C.
Received: 3 July 1996 / Accepted: 15 July 1996 相似文献
59.
Ryutaro Murakami Ayako Shigenaga Morikazu Kawakita Koichi Takimoto Ikuo Yamaoka Koji Akasaka Hiraku Shimada 《Development genes and evolution》1995,205(1-2):89-96
The proctodeum of the Drosophila embryo originates from the posterior end of the blastoderm and forms the hindgut. By enhancer-trap mutagenesis, using a P-element-lacZ vector, we identified a mutation that caused degeneration of the proctodeum during shortening of the germ band and named it aproctous (apro). Expression of the lacZ reporter gene, which was assumed to represent expression of the apro gene, began at the cellular blastoderm stage in a ring that encompassed about 10–15% of the egg's length (EL) and included the future proctodeum, anal pads, and posterior-most part of the visceral mesoderm. In later stages, strong expression of lacZ was detected in the developing hindgut and anal pads. Expression continued in the anal pads and epithelium of the hindgut of larvae; the epithelium of the hindgut of the adult fly also expressed lacZ. The spatial patterns of the expression of lacZ in various mutants suggested that the embryonic expression of apro was regulated predominantly by two gap genes, tailless (tll) and huckebein (hkb): tll is necessary for the activation of apro, while hkb suppressed the expression of apro in the region posterior to 10% EL. Cloning and sequencing of the apro cDNA revealed that apro was identical to the T-related gene (Trg) that is a Drosophila homolog of the vertebrate Brachyury gene. apro appears to play a key role in the development of tissues derived from the proctodeum. 相似文献