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91.
Morphology, endocrinology, and environmental modulation of gonadal sex differentiation in teleost fishes 总被引:1,自引:0,他引:1
Successful reproduction by an adult depends on the normal ontogenesis of the gonads, a complex process of cellular and histological
differentiation that starts early in life. This process is theoretically predetermined by genetic factors and includes sensitisation
of the bipotential gonads to endogenous endocrine factors prior to, during and even after commitment to maleness or femaleness.
However, young fish are relatively vulnerable to a host of environmental (physical and chemical) factors that can affect this
endogenous endocrine axis, disturbing or even overriding the putative developmental pathway. This sexually lability can be
exploited to our advantage for the production of monosex fish populations of the most valuable sex for food production or
aquarium fish trade. On the other hand, it represents also a potential path for undesirable influences from endocrine-disrupting
chemicals and climatic factors, particularly environmental temperature. This paper provides a detailed account of the early
histological process of gonadal sex differentiation, with special reference to gonochoristic species, and reviews the criteria
employed to positively identify ovarian and testicular differentiation. It also reviews the development of endocrine competence
and sensitivity of the differentiating gonads to exogenous influences in the context of the relative stability of genotypic
sex determination in various fish species. Sex differentiation in some species seems to be under strong genetic control and
may not require endogenous sex steroid production. Conversely, reliance on endogenous sex steroids for gonadal differentiation
is observed in other species and this phenomenon is apparently associated with a higher incidence of environment (mainly temperature)-labile
sex differentiation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
92.
Kenji Katayama Seiji Tamiya Tetsufumi Sakai Yumi Kai Akiko Ohara-Takada Toshikazu Kuranouchi Masaru Yoshinaga 《Breeding Science》2015,65(4):352-356
Sweetpotato (Ipomoea batatas (L.) Lam.), which is an outcrossing hexaploid, is one of the most important starch-producing crops in the world. During the last decade, new sweetpotato cultivars, e.g. ‘Quick Sweet’, which have approximately 20°C lower pasting temperature, slower retrogradation and higher digestibility of raw starch than ordinary cultivars, have been developed in Japan. Genetic analysis of these variants with low pasting temperature starch was conducted in this study. Using 8 variants and 15 normal clones, 26 families were generated. The results from analyzing these progenies suggested that this trait is a qualitative character controlled by one recessive allele (designated spt), which is inherited in a hexasomic manner. A dosage effect of the wild-type Spt allele was found for starch pasting temperature, although the effect was not linear. These results will aid breeders to develop sweetpotato cultivars with a range of starch pasting temperatures. 相似文献
93.
Michinari YOKOHAMA Kenta WADA Masaru FUJITA Mai KOTANI Yoshio NAGURA Masako KANNO Kou NOMURA Takashi AMANO Yoshiaki KIKKAWA 《Animal Science Journal》2011,82(6):773-781
The coat of a goat, like that of many mammalian species, consists of an outer coat of coarse hairs and an under coat of fine, downy hairs. The coarse guard hairs are produced by primary follicles and the finer cashmere hairs by secondary follicles. We previously reported that hair keratins are components of cashmere hair, and proteomic analysis revealed that their expression is elevated in winter coat hair. To determine detailed characterization, we have cloned keratin 33A gene, a major highly expressed keratin in winter, and then analyzed the expression of goat hair coat. By Western analysis, we detected that keratin 33A protein is expressed only in hair coat among the various goat tissues. Moreover, the expression level in winter has increased in cashmere high‐producing Korean native breed, whereas the expression levels between summer and winter had not changed in cashmere low‐producing Saanen. In addition, by immunohistochemistry we determined that keratin 33A is localized in the major cortex portion of cashmere fiber. These results confirm that keratin 33A is a structural protein of goat cashmere hair fiber. 相似文献
94.
Takahiro Nonaka Eriko Oka Megumi Asano Sachiko Kuwayama Hiromu Tasaki Dong-Sheng Han Toshinari Godo Masaru Nakano 《Scientia Horticulturae》2011
Lychnis (Caryophyllaceae) consists of about 30 species distributed throughout the temperate regions of the Northern Hemisphere, from East Asia to Europe. Many Lychnis spp. have high ornamental value and cultivated as pot or garden plants. In the present study, in vitro chromosome doubling of several Lychnis spp. was examined in order to widen their variability in horticultural traits. Initially effect of various spindle toxin treatments [100, 500 or 1000 mg l−1 colchicine (COL), 10, 20 or 50 mg l−1 oryzalin (ORY), or 1, 5, 10 mg l−1 amiprophos-methyl (APM)] of nodal segments of a triploid genotype of L. senno (3x) was investigated on survival of nodal segments and chromosome doubling in nodal segment-derived plantlets. Significantly higher percentage (75.0%) of surviving segments after spindle toxin treatment was obtained in 10 mg l−1 ORY treatment. Flow cytometry (FCM) analysis of leaf tissues showed that 9.4–13.8% of plantlets, which were derived from 10 to 20 mg l−1 ORY, or 5 mg l−1 APM treatments, were hexaploid (6x) or ploidy chimera (3x + 6x, 4x + 6x, 5x + 6x, 3x + 4x + 6x). The results obtained by FCM analysis were confirmed by chromosome observation in root tip cells. Thus 10 mg l−1 ORY treatment of nodal segments is suitable for in vitro chromosome doubling of triploid L. senno. Efficient chromosome doubling was also achieved in diploid L. fulgens (2x) and L. sieboldii (2x) by treating nodal segments with 10 mg l−1 ORY: 68.9–88.7% of nodal segments survived after ORY treatment, and 24.7–26.5% of plantlets derived from ORY-treated nodal segments were tetraploid (4x) or ploidy chimera (2x + 4x) in both species. These results indicate that the in vitro chromosome doubling method established for triploid L. senno may be applicable to a wide range of Lychnis spp. Tetraploid L. fulgens and L. sieboldii showed a compact plant form, and had thick stems and deep green leaves compared with the diploid mother plants. On the other hand, hexaploid L. senno showed very poor growth and died before flowering. 相似文献
95.
Diesel exhaust particle toxicity on spermatogenesis in the mouse is aryl hydrocarbon receptor dependent 总被引:1,自引:0,他引:1
Izawa H Kohara M Watanabe G Taya K Sagai M 《The Journal of reproduction and development》2007,53(5):1069-1078
Diesel exhaust particles (DEPs) are particulate matter from diesel exhaust containing many toxic compounds, such as polyaromatic hydrocarbons (PAHs). Some toxicities of PAH are considered to express via aryl hydrocarbon receptor (AhR). We hypothesized that the male reproductive toxicity of DEPs may depend on PAHs. BALB/c male mice received 24.7, 74.0 or 220 microg/mouse DEP suspension or vehicle injected into the dorsal subcutaneous layer 10 times during 5 weeks. The mice were euthanized, and blood and organs were collected 2 weeks after the last treatment. The epididymis weights, relative epididymis weights per body weight and daily sperm productions and viabilities of the 74.0 and 220 microg/mouse DEP-treated groups decreased significantly compared with those of the vehicle group. The total incidence of sperm abnormalities in the 74.0 and 220 microg/mouse DEP-treated groups increased significantly compared with the vehicle group. The seminiferous epithelium area ratios of the 74.0 and 220 microg/mouse DEP-treated groups were significantly higher compared with the vehicle and 24.6 microg/mouse DEP-treated groups. The ratios of seminiferous tubules with elongated-type spermatids in the 74.0 and 220 microg/mouse DEP-treated groups were significantly decreased compared with the vehicle group. The testosterone level and hepatic ethoxyresorufin-O-deethylase (EROD) activity as an indirect index of AhR activity in the 74.0 microg/mouse DEP-treated group were significantly increased compared with those of the vehicle group. These results clearly demonstrated that DEPs suppress testicular function, especially spermatogenesis and sperm motility. These effects may be AhR dependent. 相似文献
96.
Hajime Iri Isamu Maruta Isao Takahashi Masaru Kubota 《Soil Science and Plant Nutrition》2013,59(1):36-47
Rice fields are kept under flooded condition during the growing period of rice plant for at least three months. Soil of rice fields therefore shows consequently remarkable differences as compared with that of upland fields. This may be understood as a kind of redoxy system. Many soil constituents suffer big changes during floodtime. One of the most important constituents is iron because of its abundance in soil and its color change. 相似文献
97.
Masaru Takeya Fukuhiro Yamasaki Sachiko Hattori Akito Kaga Norihiko Tomooka 《Genetic Resources and Crop Evolution》2013,60(7):1945-1951
The National Institute of Agrobiological Sciences (NIAS) Genebank coordinates the conservation of plant, microorganism, and animal genetic resources related to food and agriculture in Japan. It also coordinates the distribution of genetic resources in the public domain for research, breeding, and educational purposes. To operate the NIAS Genebank efficiently, we have developed a genetic resources database, data management software, and web-based data retrieval systems to make the data available worldwide. This article describes the NIAS Genebank’s Core Collections of global and Japanese soybean (Glycine max (L.) Merr.), Japanese azuki bean (Vigna angularis (Willd.) Ohwi et Ohashi), and Japanese wheat (Triticum aestivum L. s. l.), all of which are available through the Genebank website. This article also describes new features of the NIAS Genebank database, such as the ability to select single-seed-derived germplasm of soybean in the plant search system and to download photographic data on accessions. By using the downloaded plant image PDF files, users can obtain detailed passport and agronomic information by clicking on the image of an accession of interest. 相似文献
98.
Masaru Sakai Yosihiro Natuhara Keitaro Fukushima Ayumi Imanishi Kensuke Imai Makoto Kato 《Journal of Forest Research》2013,18(2):190-199
Stream macroinvertebrate assemblages are expected to be affected by the abundance and constitution of litter from surrounding forests. We compared forest floor cover, overland flow, stream environment, and stream macroinvertebrate assemblages between the catchments of a Japanese cedar plantation (CP) and a primary deciduous forest (DF). Both systems experience excessive deer browsing. Understory vegetation cover was higher in the DF than in the CP in summer, although cover was low (<20 %), possibly because of excessive deer browsing. Litter cover was much higher in the CP than in the DF in summer as a result of the long abscission period, slow breakdown, and low rate of dispersal of Japanese cedar litter compared to deciduous litter. Monthly overland flow was always lower in the CP than in the DF, and substrate size was smaller in the DF stream. In the CP, cedar litter accumulated in the stream, probably because of its low breakdown rate and morphology, and abundant shredder taxa characterized the macroinvertebrate assemblage. In contrast, abundant burrower taxa characterized the macroinvertebrate assemblage in the DF stream. These results imply that Japanese cedar litter functions in structuring the macroinvertebrate assemblage by supplying persistent food resources for detritivores, and by buffering fine sedimentation via overland flow under excessive deer browsing. 相似文献
99.
Nobuo Kobayashi Masashi Matsunaga Akira Nakatsuka Daiki Mizuta Masayoshi Shigyo Masaru Akabane 《Euphytica》2013,191(1):121-128
The inheritance of organelle DNA was investigated using PCR–RFLP markers in reciprocal cross combinations of inter-subgeneric azalea hybrids between evergreen azaleas (Rhododendron nakaharai and its hybrids) and fragrant deciduous azaleas (R. arborescens and R. viscosum) for the purpose of breeding fragrant evergreen azaleas. The hybrid progenies included green leaf, pale green leaf, variegated leaf and albino seedlings. Most viable green leaf seedlings had inherited ptDNA from the deciduous parent and non-viable albino and pale green leaf seedlings had inherited ptDNA from the evergreen parent. On the other hand, variegated leaf seedlings had chimerically inherited ptDNA from both parents. Their green leaf segments had ptDNA from the deciduous parent, and the pale green and white segments had biparental or maternal ptDNA depending on the progeny. In this study, we obtained interesting inter-subgeneric azalea hybrid progenies that had chimerically inherited organelle DNA and had different colored leaf segments corresponding to the composition of ptDNA from each parent. These results suggest that variegated leaf progenies with chimeric ptDNA from both parents can be subsistent, whereas albino seedlings resulting from plastome–genome incompatibility between the plastid genome from evergreen azalea and the nuclear genome from deciduous azalea are non-viable. 相似文献
100.
Bogado-Villalba Liz Nakayama Nakashima Héctor Britos Rosanna Iehisa Julio Cesar Masaru Flores Giubi María Eugenia 《Journal of Crop Science and Biotechnology》2021,24(2):145-152
Journal of Crop Science and Biotechnology - Stevia rebaudiana (Bertoni) Bertoni is a widely grown species in various regions of the world, mainly due to its sweetening properties attributed to... 相似文献