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排序方式: 共有137条查询结果,搜索用时 31 毫秒
31.
Csar Tiago Forte Ubirajara Russi Nunes Alberto Cargnelutti Filho Leandro Galon Leonardo Chechi Rodrigo Roso Andr Dalponte Menegat Emanuel De Oliveira Rossetto Milena Barretta Franceschetti 《Weed Biology and Management》2019,19(4):113-120
Solanum americanum Mill. is a weed that occurs with a number of crops, and it is known for its high seed production and its staggered germination. The objective of this work was to evaluate the germination behavior of S. americanum seeds under the influence of chemical and environmental factors. In the laboratory, we tested the effect on germination of (i) constant and alternating temperatures, (ii) seed washing, (iii) exposure time and concentration of chemical treatments and (iv) seeding depth and soil covered with plant residue on seedling emergence. The variables analyzed were germination percentage, germination rate index, seedling emergence and length of the seedlings. The results indicated that alternating temperatures are the main way to promote germination of S. americanum; however, chemical treatments can help to increase the germination percentage and rate index. There was no increase in germination with seed washing, with the exception of KNO3 application. A GA3 concentration of 0.84 g L?1 and an exposure time of 21.22 h in 0.2% of KNO3 promoted the highest germination of S. americanum. Germination occurs when seeds remain on the soil surface and are not covered by crop residue. 相似文献
32.
33.
The presence and vasoactive effects of native calcitonin gene-related peptide (CGRP), substance P (SP), and neurokinin A (NKA)
were studied on isolated small branches of the coeliac artery from Atlantic cod, Gadus morhua, using immunohistochemistry and myograph recordings, respectively. Immunohistochemistry revealed nerve fibers containing
CGRP- and SP/NKA-like material running along the wall of the arteries. CGRP induced vasorelaxation of precontracted arteries
with a pD2 value of 8.54 ± 0.17. Relaxation to CGRP (10−8 M) was unaffected by l-NAME (3 × 10−4 M) and indomethacin (10−6 M) suggesting no involvement of nitric oxide or prostaglandins in the CGRP-induced relaxation. SP and NKA (from 10−10 to 3 × 10−7 M) contracted the unstimulated arteries at concentrations from 10−8 M and above in 42% and 33%, respectively, of the vessels. It is concluded that the innervation of the cod celiac artery includes
nerves expressing CGRP-like and tachykinin-like material, and that a vasodilatory response to CGRP is highly conserved amongst
vertebrates while the response to tachykinins is more variable. 相似文献
34.
Costa JF Kiperstok AC David JP David JM Giulietti AM de Queiroz LP dos Santos RR Soares MB 《Fitoterapia》2007,78(7-8):510-514
Ethyl acetate and chloroform extracts from aerial parts of Portulaca werdermannii and P. hirsutissima were tested in lymphoproliferation assays and axenic cultures of Leishmania amazonensis and Trypanosoma cruzi. Both extracts of P. werdermannii and P. hirsutissima had a potent inhibitory activity on lymphocyte proliferation. On the contrary, only the chloroformic extract of both plants inhibited L. amazonensis growth, without effect on T. cruzi cultures. These results indicate these Portulaca species as potential sources of new active molecules for the treatment of leishmaniasis and immune-mediated pathologies. 相似文献
35.
36.
Agnes šÖmen Joksič Sidney A. Katz Milena Horvat Radmila Milačič 《Water, air, and soil pollution》2005,162(1-4):265-283
Potential uses of dredged sediments have raised questions about leaching of contaminants from such material once transported to other locations and exposed to other environments. In order to estimate leachable, i.e. available fractions of chemical elements in such materials, a number of analytical protocols were proposed, of which none is internationally accepted as a standard procedure. As a consequence, comparability of the results obtained by different protocols in various laboratories is difficult to demonstrate. In the present study some commonly used protocols including a leaching test with (i) seawater, following the modified German Standard Method (DIN), (ii) a single extraction with 25% acetic acid, following the method proposed by the United Nations Environment Programme (UNEP), and (iii) a three-step sequential extraction, following both the original and the modified protocols of the Standards, Measurements and Testing Programme (formerly Community Bureau of Reference – BCR), were performed for assessing the availability of lead, zinc, nickel and copper leachable from dredged marine sediments. A comparison of the results obtained by the different protocols indicated that the single extraction with acetic acid is a reliable simplified technique and allows more rapid evaluations of dredged areas of coastal lagoons in the Northern Adriatic. This procedure provides information on the potentially bioavailable portion of metals. 相似文献
37.
Mendoza L Araya-Maturana R Cardona W Delgado-Castro T García C Lagos C Cotoras M 《Journal of agricultural and food chemistry》2005,53(26):10080-10084
The effect on mycelial growth of the fungus Botrytis cinerea of a set of structurally related tricyclic hydroquinones [9,10-dihydroxy-4,4-dimethyl-2,3,5,8-tetrahydroantracen-1(4H)-one and 9,10-dihydroxy-4,4-dimethyl-5,8-dihydroanthracen-1(4H)-one derivatives] and tricyclic quinones [4,4-dimethylanthracen-1,9,10(4H)-trione derivatives] was studied. In general, the anthraquinones presented higher activity than the anthrahydroquinones. Anthraquinone and anthrahydroquinone derivatives with methyl groups on the A ring showed higher antifungal activity than the unsubstituted ones, 4,4,6,7-tetramethyl-(4H)-anthracene-1,9,10-trione being the most active compound of this set. The presence of a polar group such as hydroxymethyl reduced the activity. The effect of two anthrahydroquinones and two anthraquinones on the conidia germination of the fungus was also determined. Anthrahydroquinones did not affect the germination. The most active compound was 4,4-dimethylanthracene-1,9,10(4H)-trione, with 100% inhibition of germination at 7 h of incubation. These results again suggest that the structure of the anthraquinones is important in exerting an antifungal effect on B. cinerea. Furthermore, possible mechanisms of action of compound 4,4-dimethylanthracene-1,9,10(4H)-trione were studied. This compound did not produce lipoperoxidation of membrane and did not induce the formation of oxygen reactive species, but it was able to permeabilize the plasmatic membrane of B. cinerea, increasing the phosphorus concentration in the intracellular medium. 相似文献
38.
Kuzumitsu Matsumoto Milena Luz Barbosa Luiz Augusto Copati Souza João Batista Teixeira 《Euphytica》1995,84(1):67-71
Summary The selection of tolerant variants to race 1 fusarium wilt of banana was carried out through the effects of fusaric acid onin vitro banana multiple bud clumps (MBCs). The MBCs of Maçã cultivar (Musa sp., AAB, Silk), which is susceptible to the race 1 fusarium wilt, were used. And, Nanicão cultivar (AAA, Cavendish subgroup) was used in the tolerant tests as control of a disease tolerant variety. Firstly, to aim at determining an appropriate concentration of the toxin for the tolerant selection, the MBCs were cultured on the Modified Murashige & Skoog medium supplemented with 0.05 to 1.6 mM fusaric acid. The growth on both cultivars was completely inhibited on the medium containing 0.1 mM fusaric acid.Tolerant variants of Maçã were, then, selected with 0.1 mM fusaric acid after chemical mutagen treatment. The results showed an increased tolerance of the selected Maçã plants to the race 1 fungus in greenhouse tests.
In vitro selection by fusaric acid is a very useful method for obtaining fusarium disease tolerance, although the tolerance mechanism of the selected plants may be different from that of existing tolerant cultivars. 相似文献
39.
Prediction of deoxynivalenol and zearalenone concentrations in Fusarium graminearum inoculated backcross populations of maize by symptom rating and near‐infrared spectroscopy
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Thomas Miedaner Sen Han Bettina Kessel Milena Ouzunova Tobias Schrag Friedrich H. Utz Albrecht E. Melchinger 《Plant Breeding》2015,134(5):529-534
Gibberella ear rot (GER) caused by Fusarium graminearum is a destructive disease in maize of temperate regions resulting in yield reduction and contamination by the mycotoxins deoxynivalenol (DON) and zearalenone (ZON). We wanted to analyse whether prediction of DON and ZON concentrations is feasible either by GER severity ratings or by near‐infrared spectroscopy (NIRS). We analysed 80 and 102 lines developed by backcrossing doubled‐haploid lines from segregating populations to the resistant and susceptible parent, respectively, by artificial infection at three locations in Germany and France. Both backcross (BC) populations differed substantially in their means for all traits with significant (P < 0.01) genotypic variances. DON and ZON concentrations measured by immunotests were significantly (P < 0.01) correlated with each other and with GER severity within each BC population (0.6 ≤ r ≤ 0.9, P < 0.01). DON concentration measured by immunotest and NIRS significantly correlated (r ≈ 0.9, P < 0.01). In conclusion, DON and ZON concentrations could be reliably predicted by GER severity. Additional NIRS analysis of DON concentration might be useful for the positively selected fraction. 相似文献
40.
Jörgen Jensen Paul Karila Ann-Cathrine Jönsson Göran Aldman Susanne Holmgren 《Fish physiology and biochemistry》1993,12(3):237-247
The innervation of the cod stomach by neurons showing substance P-like immunoreactivity (SPLI), and the effect and mechanism
of action of substance P (SP) on the vascularly perfused cod stomach and on isolated muscle strip preparations from the pyloric
sphincter have been investigated.
Infusion of SP produced a contraction of the stomach wall, which could not be blocked by tetrodotoxin, atropine or methysergide,
indicating a direct effect on the stomach smooth muscle. Similarly, the contraction produced by SP on preparations from the
pyloric sphincter was unaffected by tetrodotoxin.
Nerves showing SPLI were frequent in the myenteric plexus of the whole stomach, and in the submucosa and mucosa of the pyloric
part of the stomach. SPLI was also observed in fibres in the intestinal branch of the vagus and occasionally in the splanchnic
nerves. Ligation of the nerves showed an accumulation of SPLI above as well as below the ligature, being more prominent proximal
to the ligature in the vagus and distal to the ligature in the splanchnic nerve. In the vagus nerve, descending and ascending
SPLI-fibres were seen surrounding non-reactive cell bodies. No reduction in intensity of the immunoreaction of the neurons
in the stomach wall was observed after ligation or sectioning of the vagosympathetic trunk or the splanchnic nerves, nor were
SP-levels measured by radioimmunoassay reduced. After denervation of vagal branches close to the stomach wall an insignificant
decrease of immunoreactivity was observed in the myenteric plexus. Capsaicin treatment had no conclusive effect on the distribution
of SPLI.
It is concluded that the innervation showing SPLI may be of intrinsic as well as extrinsic origin, with pathways in both vagal
and splanchnic branches. Only a direct effect of SP on the smooth muscle could be demonstrated. 相似文献