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931.
932.
Taizo Nishikawa Masato Aritaki Daisuke Shimizu Toshihiro Wada Masaru Tanaka Masatomo Tagawa 《Fisheries Science》2010,76(5):827-831
The mechanism underlying malformation during flatfish metamorphosis is not clear. Here, the relationship between growth before
metamorphosis and the occurrence of malformation after metamorphosis was examined in individuals reared in a single tank.
Otoliths of starry flounder Platichthys stellatus larvae were labeled with alizarin complexone before metamorphosis [12 days after hatching (DAH)]. The positive linear regression
between the lapillus otolith diameter and body length at 12 DAH enabled the estimation of individual larval size after completion
of metamorphosis. At 12 DAH, the average body length of the typical pseudoalbino juveniles was significantly greater (5.37 mm)
than that of the normal juveniles (5.13 mm) (P < 0.01, n = 100). In addition, of the larvae that were estimated to measure less than 4.8 mm at 12 DAH, approximately 80% metamorphosed
into normal juveniles, whereas more than 60% of the larvae that measured more than 5.4 mm became pseudoalbino juveniles. These
results indicate that the larvae that grow rapidly during the first 12 days are more likely to become pseudoalbino individuals
after metamorphosis. 相似文献
933.
Kazufumi Osako Hiroaki Saito Wuyin Weng Koichi Kuwahara Munehiko Tanaka 《Fisheries Science》2009,75(4):1055-1066
To characterize the 22:6 n-3 (docosahexaenoic acid, DHA) levels of the oriental bonito Sarda orientalis, a coastal migratory tuna species, total lipids (TL) of white muscle, dark muscle, liver, pyloric cecum, gonad, and other
viscera were separated into lipid classes, the constituents of TL were quantified, and the fatty acid composition of TL, triacylglycerols
(TAG), phosphatidylethanolamine, and phosphatidylcholine was analyzed. The crude lipid contents of muscle and other organs
were 0.8–3.2% and 2.3–9.1%, respectively. DHA was found in TL of various organs at levels ranging from 19.2% to 27.6% in muscle
and 16.3% to 28.5% in other organs. The levels of DHA in muscle TAG (8.2–16.0%) were lower than or comparable to those in
visceral TAG (6.9–24.0%). These findings did not coincide with those observed in active-migratory tuna species, which accumulate
DHA in their muscle TAG during migration. These findings suggest that the DHA distribution of S. orientalis is different from that observed in active-migratory tuna species, and that the differences may be due to migration type of
the fish. 相似文献
934.
Akihiro Okamura Yoshiaki Yamada Noriyuki Horie Naomi Mikawa Satoru Tanaka Hideki Kobayashi Katsumi Tsukamoto 《Aquaculture Research》2013,44(10):1531-1538
Usual diets for rearing leptocephalus larvae of Japanese eel Anguilla japonica include eggs of the endangered spiny dogfish Squalus acanthias (SE). We investigated the effects of alternative food materials, hen egg yolk (HEY) and exoskeleton‐free (skinned) Antarctic krill (SAK), on the growth and survival of eel larvae. We found that feed comprising whole krill including exoskeleton (WAK) containing higher levels of fluoride (37.89 mg kg?1) was acutely toxic to eel larvae exposed to this alone. In contrast, extract from SAK containing lower concentrations of fluoride (4.25 mg kg?1) showed no apparent adverse effects. Growth of larvae fed a mixture of SE and SAK in a feed trial of 58 days [mean body weight (BW), 6.0 mg] was about twofold higher than that of larvae fed a mixture of SE and WAK (3.2 mg) (P < 0.01). A mixture of HEY and SAK also had some dietary benefits for eel larvae, enabling them to survive for up to 58 days and to grow significantly (mean BW, 2.4 mg), compared with their initial weight (mean BW, 0.2 mg) (P < 0.001). Although additional nutritional improvements are needed, the present results suggest that combination diet HEY and SAK may be a good alternative to SE as an effective diet for eel larvae. 相似文献
935.
Pham KX Amano M Kurita Y Shimizu A Fujinami Y Amiya N Yamamori K 《Fish physiology and biochemistry》2008,34(4):357-365
The role of gonadotropin (GTH) in the reproduction of the Japanese flounder, Paralichthys olivaceus, was studied by assessing the changes in the apparent activity of follicle-stimulating hormone (FSH) and luteinizing hormone
(LH) in the pituitary gland during gonadal maturation by immunohistochemical analyses. Corresponding changes in plasma levels
of testosterone (T), estradiol-17β (E2), and 17α,20β-dihydroxy-4–pregnen-3-one (DHP) were also studied. Reared fish at the early spawning to termination stages
were sampled from May to August and wild fish at the previtellogenic to termination stages were caught at 3- to 4-week intervals
between April and September offshore from the northern mainland of Japan by gill nets. The gonadosomatic index of the reared
fish decreased from the early spawning stage to the termination stage, while that of the wild fish increased significantly
from the previtellogenic stage to the early spawning stage and decreased thereafter. In the reared fish, the immunostaining
intensities of FSH and LH were high during the spawning period, accompanied by high plasma levels of T, E2, and DHP. In the wild fish, the immunostaining intensities of FSH and LH were low during the previtellogenic stage but increased
during the maturing and spawning stages. These results indicate that both FSH and LH are likely associated with oocyte maturation
in the Japanese flounder. 相似文献
936.
Daisuke Shimizu Yuichiro Fujinami Sayumi Sawaguchi Takahiro Matsubara 《Fisheries Science》2012,78(6):1245-1252
The objective of this study is to establish a method for acquiring large quantities of high-quality eggs for artificial fertilization from hatchery-reared broodstock of spotted halibut Verasper variegatus. We estimated the optimum conditions for implantation of luteinizing hormone-releasing hormone analog (LHRHa) cholesterol pellet (LHRHa-CP) to induce ovulation from two experiments which focused on the dose and the timing combined with monitoring of oocyte development by ovarian cannulation. From the results of cannulation, vitellogenesis of hatchery-reared broodstock was suggested to occur normally, although final oocyte maturation was not initiated in the first clutch of oocytes. In late December, oocytes in the most advanced clutch still underwent vitellogenesis, having diameter of about 0.82?mm. LHRHa-CP implantation during this period had no remarkable effects, except for administration at high dose (100???g/kg). In contrast, in mid January, when oocyte diameter reached about 0.95?mm, ovulation occurred in most individuals, even at low dose (20???g/kg). In mid February atretic oocytes became remarkable and LHRHa-CP implantation showed much lower performance in terms of egg quality. The diameter of growing oocytes converged to about 0.95?mm, which was that of fully grown postvitellogenic oocytes. Thus, oocyte diameter is suggested to be an effective indicator to estimate the timing of LHRHa-CP implantation. 相似文献
937.
Mari Inohana Takeshi Komine Yoshiaki Tanaka Osamu Kurata Shinpei Wada 《Journal of fish diseases》2023,46(1):47-59
Mycobacterium marinum is a prevalent nontuberculous mycobacterium (NTM)-infecting teleosts. Conversely, little is known about mycobacteriosis in elasmobranchs, and M. marinum infection has never been reported from the subclass. This study investigated the histopathological characteristics and localization of this mycobacterium through molecular analysis of two captive sharks, a scalloped hammerhead Sphyrna lewini and a Japanese bullhead shark Heterodontus japonicus, exhibited in the same aquarium tank. We detected genital mycobacteriosis caused by M. marinum infection using molecular analyses, including polymerase chain reaction (PCR) and DNA sequencing targeting the 60 kDa heat-shock protein gene (hsp65), and peptide nucleic acid–fluorescence in situ hybridization (PNA-FISH) targeting the 16S rRNA gene. Both sharks showed granulomas in connective tissues of the gonads without central necrosis or surrounding fibrous capsules, which is unlike the typical mycobacterial granulomas seen in teleosts. This study reveals that elasmobranchs can be aquatic hosts of M. marinum. Because M. marinum is a representative waterborne NTM and a potential zoonotic agent, cautious and intensive research is needed to overcome a lack of data on the relationship between NTM and the aquatic environment in association with this subclass of Chondrichthyes. 相似文献
938.
Hui Chen Atsushi Tamai Masashi Mori Masashi Ugaki Yoshikazu Tanaka Partha P. Samadder Akio Miyao Hirohiko Hirochika Naoto Yamaoka Masamichi Nishiguchi 《Journal of General Plant Pathology》2010,76(2):152-160
RNA-dependent RNA polymerases (RDRs) play a key role in various RNA silencing pathways in many organisms. Using the nucleotide
sequence of SGS2/SDE1/RDR6 in Arabidopsis as the search query for sequences that flank the insertions of rice retrotransposon Tos17, we selected rice mutant lines (OsRDR1). RT-PCR analysis showed that OsRDR1 mRNA was undetectable in leaves and calli of the mutants, while it was detected in wild type. RNA silencing was induced by
particle bombardment to investigate any effects of OsRDR1 on RNA silencing with β-glucuronidase or green fluorescent protein DNA/RNA in the mutant lines. The results showed that RNA
silencing was impaired in these mutant lines by inverted repeat (IR) DNA or in vitro transcribed double-stranded RNA. Further,
the mutant lines were bombarded with Brome mosaic bromovirus (BMV, a ssRNA virus) or Wheat dwarf
geminivirus (WDV, a ssDNA virus), each carrying the IR sequence of a reporter gene. As a result, RNA silencing was impaired by BMV. Interestingly,
however, it was not impaired by WDV. Thus we propose that OsRDR1 is required for RNA silencing mediated by Bromovirus, but not by Geminivirus in this system. 相似文献
939.
Ying-Hong He Sayaka Isono Yoko Kawaguchi-Ito Akito Taneda Ken-ichi Kondo Akihiko Iijima Kazuaki Tanaka Teruo Sano 《Journal of General Plant Pathology》2010,76(5):324-330
A 303-nucleotide viroid was isolated from an apple tree (Malus × domestica, ‘Fuji’) cultivated in Japan. The viroid had 84.9% overall nucleotide sequence homology to Apple dimple fruit viroid (ADFVd), a member of Pospiviroidae, reported from Italy. This viroid differed from the Italian variant by 47 mutations (38 substitutions, six deletions and three insertions), and most of these mutations occurred on either side of the central conserved region. The leaves and branches of the infected trees did not have any disease symptoms, but the fruits were dimpled and yellow. The infected scions were top-grafted onto a healthy ‘Fuji’ apple tree, which tested positive for this viroid in a northern hybridization analysis, and yellow dimple fruits were produced in the second growing season. We propose that this viroid is a new variant of ADFVd and causes yellow dimple fruit formation in ‘Fuji’ apple trees. 相似文献
940.
Tanaka Kenzo Reiji Yoneda Mohamad Alias Azani Nik Muhamad Majid 《Journal of Forest Research》2008,13(2):137-142
Leaf hairs may assist in maintaining high leaf water use efficiency in tropical secondary forest tree species. We compared
leaf temperature, transpiration, photosynthesis and water use efficiency between hairy and depilated leaves in Mallotus macrostachyus (Euphorbiaceae), to determine the role of leaf hair in leaf water use efficiency (WUE) in tropical degraded secondary forest
in Malaysia. Measurements were made on five mature individuals growing in sun-exposed conditions and five in shaded conditions.
The hair dry weight per unit leaf area was significantly greater in sun leaves than in shade leaves. The transpiration rate
(Trmax) of depilated leaves in sun-exposed conditions was slightly higher than in hairy leaves in both morning and afternoon measurements.
In contrast, Trmax in the shade leaves was almost identical in hairy and depilated leaves. Leaf stomatal conductance (g
s) in the morning showed almost the same value among leaf types and light conditions. In the afternoon, g
s slightly decreased from the morning values in both sun and shade conditions. In the morning, the leaf water use efficiency
(A
max/Trmax) in both conditions did not differ significantly between hairy and depilated leaves. However, in the afternoon, WUE in the
depilated leaves was significantly lower than in hairy leaves in sun-exposed conditions. These observations suggest that leaf
hairs in M. macrostachyus contribute to the high leaf water use efficiency in drought conditions, such as high vapor pressure deficit experienced at
midday in degraded tropical secondary forests. 相似文献