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41.
42.
An attempt was made to account for quantitatively measured herbicidal performance of foliage-applied 5-hydroxy-3-methyl-2–oxo-imidazolidine-1-carboxamide derivatives by their photosynthesis-inhibiting activity and systemicity. Photosynthesis-inhibiting activity was estimated from the increase of chlorophyll fluorescence intensity in Chlorella vulgaris Beijer cells measured by a microplate scanner, and systemicity was also evaluated by computer-aided chlorophyll fluorescence imaging. The highest herbicidal performance was recorded for N-cyclohexyl-5-hydroxy-3-methyl-2-oxo-imidazo~idine-l-carboxamide, a compound with the second strongest photosynthesis-inhibiting activity and intermediate systemicity. Though neither photosynthesis-inhibiting activity nor systemicity showed significant correlation with the actual herbicidal performance in simple regression analyses, a high predictability was found for a multiple regression on both parameters as two independent variables, suggesting that these two factors work cooperatively in the field performance. 相似文献
43.
44.
Yasuro Iwashita Nobuhiro Suzuki Hiroyuki Matsunari Tsuyoshi Sugita Takeshi Yamamoto 《Fisheries Science》2009,75(5):1307-1315
To investigate the cause of the changes in intestinal morphology and biliary bile status of rainbow trout Oncorhynchus mykiss fed defatted soybean meal (SBM)-based diets, casein-based semipurified diets supplemented with soya saponin, soya lectin,
and cholyltaurine were fed to rainbow trout for 6 weeks. An unsupplemented control diet and a SBM-based diet were also tested
as references. Poor development of microvilli and pinocytotic vacuoles, and accumulation of large vacuoles in the epithelial
cells were observed in the distal intestine of fish fed diets containing saponin but not cholyltaurine. Hyperplastic connective
tissue in the mucosal folds of the distal intestine was observed in fish fed a diet containing both saponin and lectin but
not cholyltaurine. However, intestinal histological features in fish fed diet supplemented with cholyltaurine and lectin and/or
saponin were similar to those in the control diet group. Liver morphology and biliary bile status were not affected by saponin
and lectin. These results suggest that the abnormal features of the distal intestine of rainbow trout fed SBM-based diets
are caused by the combination of soya saponin and soya lectin, and that supplemental cholyltaurine plays certain roles in
normalizing the intestinal abnormalities caused by the saponin and lectin. 相似文献
45.
Neoh TL Yamauchi K Yoshii H Furuta T 《Journal of agricultural and food chemistry》2007,55(26):11020-11026
1-methylcyclopropene (1-MCP), an ethylene inhibiting regulator, is commercially available in the form of an inclusion complex with alpha-cyclodextrin (alpha-CD). In this study, molecular encapsulation of gaseous 1-MCP into aqueous alpha-CD was investigated in a closed, agitated vessel with a flat gas-liquid interface. Molecular encapsulation of gaseous 1-MCP by alpha-CD is a simultaneous two-step reaction which involves the aqueous dissolution of gaseous 1-MCP and the encapsulation of the dissolved molecules by alpha-CD. The kinetics and mechanism of molecular encapsulation were analyzed based on the depletion rate of 1-MCP in the headspace of the vessel. The encapsulation rates could be explained quantitatively by the gas absorption theory with a pseudo-first-order reaction between 1-MCP and alpha-CD. The negative value of the calculated apparent activation energy of encapsulation (-24.4 kJ/mol) implied the significant effect of exothermic aqueous dissolution of 1-MCP. An encapsulation temperature of 15 degrees C was optimal; at this temperature, the highest 1-MCP yield and best inclusion ratio of inclusion complex were obtained. Changes in the X-ray diffraction pattern suggested that the crystal lattice structure of alpha-CD was altered upon inclusion of 1-MCP. 相似文献
46.
Takeshi Katayama Jyoji Tsutsui Kazuo Tsueda Takao Miki Yasuhiro Yamada Murao Sogo 《Journal of Wood Science》2000,46(6):458-465
When (±)--oxo-guaiacylglycerol--(vanillic acid) ether (1) is degraded byFusarium solani M-13-1, the-ketone is initially reduced to giveerythro andthreo guaiacylglycerol--(vanillic acid) ethers (2), arylglycerol--aryl ethers, both of which are enantiomerically pure. The absolute configuration in each2 was determined by Mosher's method; the products were converted to,-di-(R)--methoxy--trifluoromethylphenylacetates (MTPA esters) (3) oferythro (-)- andthreo (+)-veratrylglycerol--(methyl vanillate) ethers (3), whose1H nuclear magnetic resonance (NMR) spectra were examined and compared with those of four di-(R)-MTPA ester (3) diastereomers from chemically synthesizederythro (±)-3 andthreo (±)-3. To assign the- and-MTPA-OCH3 peaks, the1H NMR scans of several compounds that have substructures of 3 and their 3,4,5-trimethoxyphenyl analogues were examined. When a racemic alcohol reacts with (R)-MTPA to give a pair of (R)-MTPA ester diastereomers, the value was defined as the absolute value of the difference in the1H chemical shifts of the peak between the diastereomers. It was found that the values of-MTPA-OCH3 were larger than those of-MTPA-OCH3 owing to a shielding effect of the veratryl ring located on the-MTPA-OCH3, and that the-MTPA-OCH3 peaks in the 3,4,5-trimethoxyphenyl compounds shifted downfield relative to those in the veratryl compounds. On the basis of the1h NMR data of (R)-MTPA esters, the absolute configuration of the four chemically prepared diastereomers (3) were determined. The catabolicerythro
3 [fromerythro (-)-3] andthreo
3 [fromthreo (+)-3] were identical to (R, S, R)-erythro
3 and (R, S, S)- threo
3, respectively. An hydrogen species in the fungal reduction would attack the-ketone fromre-face of both (R)-1 and (S)-1, givingerythro (S, R)-2 andthreo (S, S)-2, respectively.Part of this paper was presented at the 33rd Lignin Symposium, Tsukuba, November 1988 相似文献
47.
Yutaka Kataoka Makoto Kiguchi Takeshi Fujiwara Philip D. Evans 《Journal of Wood Science》2005,51(5):531-536
Low density wood is more rapidly eroded than denser wood when exposed to the weather, possibly because it is more susceptible
to photodegradation. Fourier transform infrared microscopy was used to examine: (1) the depth of photodegradation in earlywood
and latewood of sugi (Japanese cedar) and earlywood of hinoki (Japanese cypress) exposed for up to 1500 h to artificial sunlight
emitted by a xenon lamp (375 W/m2 within the 300 to 700 nm spectral range); and (2) the relationship between the density of wood tissues and depth of photodegradation.
The depth of photodegradation varied between species (sugi and hinoki) as well as within a growth ring (sugi earlywood and
latewood), and there was an inversely proportional relationship between depth of photodegradation and wood density. These
findings may explain why low density earlywood is more rapidly eroded than latewood during weathering, and more generally,
why there is an inverse relationship between the density of wood species and their rate of erosion during artificial and natural
weathering.
Part of this work was presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, August 2004 相似文献
48.
49.
Spermatogenesis and its endocrine regulation 总被引:2,自引:2,他引:2
Three major phases compose spermatogenesis: mitotic proliferation of spermatogonia, meiosis of spermatocytes, and spermiogenesis,
the restructuring of spermatids into flagellated spermatozoa. The process is fuelled by stem cells that, when dividing, either
self-renew or produce spermatogonia that are committed to proliferation, meiosis, and spermiogenesis. During all phases, germ
cells are in close contact with and require the structural and functional support of Sertoli cells. In contrast to germ cells,
these somatic cells express receptors for sex steroids and follicle-stimulating hormone (FSH), the most important hormones
that regulate spermatogenesis. A typical Sertoli cell response to an endocrine stimulus would be to change the release of
a growth factor that would then mediate the hormone's effect to the germ cells. Recent studies in the Japanese eel have shown,
for example, that in the absence of gonadotropin Sertoli cells produce a growth factor (an orthologue of anti-Müllerian hormone)
that restricts stem cell divisions to the self-renewal pathway; also estrogens stimulate stem cell renewal divisions but not
spermatogonial proliferation. Gonadotropin or 11-ketotestosterone (11-KT) stimulation, however, induces spermatogonial proliferation,
which is in part mimicked by another Sertoli cell-derived growth factor (activin B). Since FSH (besides luteinizing hormone,
LH) stimulates steroidogenesis in fish, and since FSH is the only gonadotropin detected in the plasma of sexually immature
salmonids, increased FSH signalling may be sufficient to initiate spermatogenesis by activating both Sertoli cell functions
and 11-KT production. Another important androgen is testosterone (T), which seems to act via feedback mechanisms that can
compromise FSH-dependent signalling or steroidogenesis. The testicular production of T and 11-KT therefore needs to be balanced
adequately. Further research is required to elucidate in what way(s) 11-KT stimulates later stages of development, such as
entry into meiosis and spermiogenesis. At this period, LH becomes increasingly important for the regulation of androgen production.
Results from mammalian models suggest that during the later phases, the control of germ cell apoptosis via Sertoli cell factors
is an important regulatory mechanism. In many species, sperm cells cannot fertilize eggs until having passed a maturation
process known as capacitation, which includes the acquisition of motility. Progestins that are produced under the influence
of LH appear to play an important role in this context, which involves the control of the composition of the seminal plasma
(e.g., pH values).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
50.
Miyazawa K Aso H Honda M Kido T Minashima T Kanaya T Watanabe K Ohwada S Rose MT Yamaguchi T 《Research in veterinary science》2006,81(1):40-45
Dendritic cells (DCs) are professional antigen presenting cells, which initiate primary immune responses and also play an important role in the generation of peripheral tolerance. There is no reliable method established for the isolation of bovine peripheral blood DCs, and furthermore, the phenotypes and the functions of bovine DCs are still not fully clear. In the present study, we have attempted to identify bovine peripheral blood DCs by negative-selection. In bovine peripheral blood mononuclear cells (PBMC), we have newly characterized the phenotype of DCs, which is CD11c+/CD172a+. These cells display features of myeloid type DCs. In the thymic medulla, CD11c+/CD172a+ cells were also present and CD1+/CD172a+ cells were additionally detected as a population of DCs. The data suggest that one of the bovine DCs phenotypes from PBMC is derived from myeloid lineages lacking a CD1 molecule, which then drift to several tissues, and that they then may express a CD1 molecule upon their functional differentiation. 相似文献