全文获取类型
收费全文 | 2441篇 |
免费 | 165篇 |
国内免费 | 1篇 |
专业分类
2607篇 |
出版年
2021年 | 22篇 |
2020年 | 13篇 |
2019年 | 12篇 |
2018年 | 29篇 |
2017年 | 23篇 |
2016年 | 45篇 |
2015年 | 77篇 |
2014年 | 79篇 |
2013年 | 166篇 |
2012年 | 85篇 |
2011年 | 134篇 |
2010年 | 94篇 |
2009年 | 101篇 |
2008年 | 123篇 |
2007年 | 140篇 |
2006年 | 125篇 |
2005年 | 123篇 |
2004年 | 104篇 |
2003年 | 100篇 |
2002年 | 121篇 |
2001年 | 94篇 |
2000年 | 71篇 |
1999年 | 72篇 |
1998年 | 24篇 |
1997年 | 28篇 |
1996年 | 20篇 |
1995年 | 24篇 |
1994年 | 32篇 |
1993年 | 26篇 |
1992年 | 42篇 |
1991年 | 40篇 |
1990年 | 41篇 |
1989年 | 35篇 |
1988年 | 37篇 |
1987年 | 29篇 |
1986年 | 28篇 |
1985年 | 33篇 |
1984年 | 25篇 |
1983年 | 22篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 25篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1973年 | 13篇 |
1972年 | 6篇 |
1969年 | 8篇 |
1966年 | 6篇 |
排序方式: 共有2607条查询结果,搜索用时 0 毫秒
61.
62.
Dominance among male chimpanzees in the Mahale Mountains National Park,Tanzania: A preliminary study
Hitoshige Hayaki Michael A. Huffman Toshisada Nishida 《Primates; journal of primatology》1989,30(2):187-197
Dominance relationships among male chimpanzees in the Mahale Mountains National Park, Tanzania, were analyzed. Although all
adolescent males were unequivocally subordinate to all adult males, dominance relationships within the age classes were much
less clear. Especially among adolescent males, few pant-grunts or agonistic interactions occurred. While adolescent males
frequently pant-grunted at adult males, these latter males, except the alpha and the youngest, rarely pant-grunted to one
another. This suggests that a difference of social status exists between adolescent and adult males. Adult males rarely display
overt dominance to one another probably because the presence of other males affects their interactions. Moreover, they seem
to try to keep their dominance relationship ambiguous when making it overt is not advantageous to them. This may be a political
way for males to coexist with one another in a unit-group. 相似文献
63.
H Takeya S Nishida T Miyata S Kawada Y Saisaka T Morita S Iwanaga 《The Journal of biological chemistry》1992,267(20):14109-14117
We determined the complete amino acid sequence of RVV-X, the blood coagulation factor X activating enzyme, isolated from Russell's viper venom and studied structure-function relationships. RVV-X (M(r) 79,000) consists of a disulfide-bonded two-chain glycoprotein with a heavy chain of M(r) 59,000 and a light chain of heterogeneous M(r) 18,000 (LC1) and 21,000 (LC2). These chains were separated after reduction and S-pyridylethylation, and the isolated major component LC1 was used for sequence analysis. The heavy chain consists of 427 residues containing four asparagine-linked oligosaccharides, and its entire sequence was similar to that of the high molecular mass hemorrhagic protein, HR1B, isolated from the venom of Trimere-surus flavoviridis. The heavy chain contains three distinct domains, metalloproteinase, disintegrin (platelet aggregation inhibitor)-like and unknown cysteine-rich domains. On the other hand, light chain LC1 consists of 123 amino acid residues containing one asparagine-linked oligosaccharide and shows sequence homology similar to that found in the so-called C-type (Ca(2+)-dependent) lectins. Therefore, RVV-X is a novel metalloproteinase containing a mosaic structure with distintegrin-like, cysteine-rich, and C-type lectin-like domains. RVV-X potently inhibits collagen- and ADP-stimulated platelet aggregations, probably via its distintegrin-like domain, although this domain does not contain the Arg-Gly-Asp sequence which is conserved in various venom distintegrins and which is thought to be one of the interaction sites for platelet integrins. Our findings also indicate that snake venom factor IX/factor X-binding protein with a C-type lectin structure (Atoda, H., Hyuga, M., and Morita, T. (1991) J. Biol. Chem. 266, 14903-14911) inhibits RVV-X-catalyzed factor X activation; hence, the light chain of RVV-X probably participates in recognizing some portion of the zymogen factor X. 相似文献
64.
Fluorescent microscopy was proved to be effective for structural identification of permineralized plant tissues in calcite
nodules from the Upper Cretaceous of Hokkaido, Japan. A minute, scale-like projection on the bract of a fossil Taxodiaceous
cone is identified as a true ovuliferous scale because it is bordered with a continuous epidermis that exhibits prominent
fluorescence. The presence of the ovuliferous scale suggests that the fossil is aTaiwania archetype. 相似文献
65.
Terashima Ichiro; Sonoike Kintake; Kawazu Tamotsu; Katoh Sakae 《Plant & cell physiology》1991,32(8):1275-1283
To examine the effects of chilling of leaves of cucumber (Cucumissativus L.) in moderate light on the coupling state of thylakoidsin situ, changes in fluorescence, changes in light scatteringand flash-induced changes in absorbance at 518 nm were examinedin intact leaves. After chilling of leaves at 5?C in the lightfor 5 h, the non-photochemical quenching of fluorescence, ameasure of energisation of thylakoids, was largely suppressed.The treatment also caused a suppression of light-induced changesin the light scattering by leaves, which depends on the formationof a pH gradient across thylakoid membranes. When thylakoidswere prepared by very gentle methods from the leaves chilledin the light, through a step of preparation of intact chloro-plasts,the transport of electrons from H2O to ferricyanide was uncoupled,being insensitive to an uncoupler, methylamine. These data provide consistent evidence that the thylakoids areuncoupled in situ by the chilling of leaves in the light and,as a consequence of the uncoupling, the energisation of themembranes is suppressed. However, the decay of the flash-inducedchange in absorbance at 518 nm in leaves was not markedly acceleratedby the treatment. The thylakoids isolated from leaves chilledin the light, which were in the uncoupled state, also did notshow a rapid decay, unless an efficient uncoupler such as gramicidinwas added. These results suggest that even a considerable uncouplingof thylakoids, brought about by chilling of leaves in the light,is not sufficient to cause a marked acceleration of the decayof the flash-induced change in absorbance at 518 nm. Therefore,analysis at 518 nm is not always a sensitive method for assessingthe coupling state of thylakoids. (Received July 1, 1991; Accepted October 4, 1991) 相似文献
66.
Itoh Hiroya Miura Ai Matsui Makoto Arazoe Takayuki Nishida Keiji Kumagai Toshitaka Arita Masanori Tamano Koichi Machida Masayuki Shibata Takashi 《Applied microbiology and biotechnology》2018,102(3):1393-1405
Applied Microbiology and Biotechnology - In the production of useful microbial secondary metabolites, the breeding of strains is generally performed by random mutagenesis. However, because random... 相似文献
67.
H Nishida 《Development (Cambridge, England)》1990,108(4):559-568
Muscle cells of the ascidian larva originate from three different lines of progenitor cells, the B-line, A-line and b-line. Experiments with 8-cell embryos have indicated that isolated blastomeres of the B-line (primary) muscle lineage show autonomous development of a muscle-specific enzyme, whereas blastomeres of the A-line and b-line (secondary) muscle lineage rarely develop the enzyme in isolation. In order to study the mechanisms by which different lines of progenitors are determined to give rise to muscle, blastomeres were isolated from embryos of Halocynthia roretzi at the later cleavage stages when conspicuous restriction of the developmental fate of blastomeres had already occurred. Partial embryos derived from B-line muscle-lineage cells of the 64-cell embryo (B7.4, B7.5 and B7.8) showed autonomous expression of specific features of muscle cells (acetylcholinesterase, filamentous actin and muscle-specific antigen). In contrast, b-line muscle-lineage cells, even those isolated from the 110-cell embryo (b8.17 and b8.19), did not express any muscle-specific features, even though their developmental fate was mainly restricted to generation of muscle. Isolated A-line cells from the 64-cell embryos (A7.8) did not show any features of muscle differentiation, whereas some isolated A-line cells from the 110-cell embryos (A8.16) developed all three above-mentioned features of muscle cells. This transition was shown to occur during the eighth cell cycle. These results suggest that the mechanism involved in the process of determination of the secondary-lineage muscle cells differs from that of the primary-lineage muscle cells. Interaction with cells of other lineages may be required for the determination of secondary precursors to muscle cells. The presumptive b-line and A-line muscle cells that failed to express muscle-specific features in isolation did not develop into epidermal cells. Thus, although interactions between cells may be required for muscle determination in secondary lineages, the process may represent a permissive type of induction and may differ from the processes of induction of mesoderm in amphibian embryos. 相似文献
68.
Sachiko Nishida Koh-Ichi Takakura Takayoshi Nishida Takashi Matsumoto Masahiro M. Kanaoka 《Biological invasions》2012,14(2):439-447
Reproductive interference (RI) has been suggested to play a critical role in native plant displacement by alien congeners.
However, although co-existence of native and alien congeners may provide an opportunity to refute the RI hypothesis, few studies
have examined such a case. Using a native Japanese dandelion, Taraxacum longeappendiculatum, and a co-existing alien congener, Taraxacum officinale, we tested the hypothesis that differences in RI by the alien between native recipient congeners explain whether a native
will co-exist with or be displaced by an alien. We conducted a field survey to investigate the effects of alien relative abundance
on T. longeappendiculatum seed set, and a hand-pollination experiment to identify the extent of pollen interference by the alien on T. longeappendiculatum. We compared these results with those obtained previously for another Japanese native species, Taraxacum japonicum, which was displaced by the alien. In our field survey, alien relative abundance had little effect on seed set in nearby
T. longeappendiculatum, and hand-pollination with mixed pollen grains produced no substantial decrease in seed set of the native species. Model
selection supported these tendencies; the effect of RI by the alien differed between the two native species. Other potential
factors, such as resource competition or habitat changes, could not explain the co-existence of T. longeappendiculatum with and exclusion of T. japonicum by the alien in the same explanatory framework. Considering the consistent explanatory power, the findings suggest that RI
is a critical mechanism that can determine both co-existence with and displacement of native dandelions by an alien congener. 相似文献
69.
70.
Kunimoto K Yamazaki Y Nishida T Shinohara K Ishikawa H Hasegawa T Okanoue T Hamada H Noda T Tamura A Tsukita S Tsukita S 《Cell》2012,148(1-2):189-200
Highlights? Mice expressing truncated Odf2 cough and sneeze due to primary ciliary dyskinesia ? Full-length Odf2 is needed for the formation of basal body-associated basal feet ? In the absence of basal feet, basal bodies fail to align with planar polarity cues ? Polarization of basal bodies by Odf2 is required for coordinated ciliary beating 相似文献