全文获取类型
收费全文 | 7487篇 |
免费 | 47篇 |
国内免费 | 14篇 |
专业分类
林业 | 728篇 |
农学 | 245篇 |
基础科学 | 49篇 |
921篇 | |
综合类 | 332篇 |
农作物 | 506篇 |
水产渔业 | 462篇 |
畜牧兽医 | 3600篇 |
园艺 | 201篇 |
植物保护 | 504篇 |
出版年
2022年 | 14篇 |
2019年 | 10篇 |
2018年 | 121篇 |
2017年 | 186篇 |
2016年 | 171篇 |
2015年 | 236篇 |
2014年 | 204篇 |
2013年 | 155篇 |
2012年 | 447篇 |
2011年 | 306篇 |
2010年 | 108篇 |
2009年 | 73篇 |
2008年 | 63篇 |
2007年 | 38篇 |
2006年 | 40篇 |
2005年 | 774篇 |
2004年 | 652篇 |
2003年 | 446篇 |
2002年 | 110篇 |
2001年 | 130篇 |
2000年 | 33篇 |
1999年 | 146篇 |
1992年 | 117篇 |
1991年 | 145篇 |
1990年 | 168篇 |
1989年 | 147篇 |
1988年 | 171篇 |
1987年 | 113篇 |
1986年 | 143篇 |
1985年 | 117篇 |
1984年 | 91篇 |
1983年 | 81篇 |
1982年 | 33篇 |
1981年 | 17篇 |
1980年 | 23篇 |
1979年 | 133篇 |
1978年 | 96篇 |
1977年 | 91篇 |
1976年 | 77篇 |
1975年 | 137篇 |
1974年 | 129篇 |
1973年 | 116篇 |
1972年 | 138篇 |
1971年 | 118篇 |
1970年 | 88篇 |
1969年 | 102篇 |
1968年 | 113篇 |
1967年 | 125篇 |
1966年 | 102篇 |
1965年 | 70篇 |
排序方式: 共有7548条查询结果,搜索用时 15 毫秒
241.
Ilhami Kiziro?lu Levend Turan Ali Erdo?an ?zdemir Adizel Nahit Pamuko?lu 《Anzeiger für Sch?dlingskunde》2002,37(1):99-102
Analysis of nestling food in four species of Parus and one species of Ficedula using the 'Halsringmethode' showed a high quota of adults and caterpillars of the important forest pests: Tortrix viridana, Euproctis chrysorrhoea, Diprion pini, and Lymantria dispar. These four major pest species amounted in the nestling food of Parus major to 50%, P. coeruleus to 52.6%, P. ater to 40.9%, and Ficedula hypoleuca to 30.2%. 相似文献
242.
Phytophthora root rot, caused byPhytophthora cinnamomi Rands, is the most important disease of avocado (Persea americana Miller). In an attempt to identify root rot-resistant rootstocks that could ultimately be used under conditions in southern
Florida, we screened open-pollinated progeny of avocado from the National Germplasm Repository in Miami. From 1996 to 1998,
a total of 2,355 seedlings from 51 accessions were examined in potting mix artificially infested withP. cinnamomi. Most seedlings developed severe root rot, but tolerance was observed in some families (i.e., progeny of certain accessions). Although the most susceptible families developed mean disease ratings of up to 97% root
necrosis, mean ratings for the most tolerant families were less than 60%. There was also a strong relationship between the
racial background of the female parent and the tolerance of seedlings. Seedlings of the West Indian race and hybrids between
it and the Guatemalan race were significantly more tolerant than those from other parents (P< 0.05). Individuals in several
families developed < 50% root necrosis, the arbitrary standard of tolerance in this study. Twelve families accounted for 82%
(188 of 229) of the tolerant seedlings, and only two of these did not have a West Indian or Guatemalan × West Indian pedigree.
Broad-sense heritability for PRR tolerance was 0.45. This is the first report on the inheritance of PRR tolerance in avocado
and on the influence of genotype and racial pedigree under controlled conditions. 相似文献
243.
Orobanche amethystea Thuill.,O. loricata Reichenb. andO. pubescens D’Urv. were found to parasitize the roots of cultivated plants in Israel.Orobanche pubescens is known from the local flora, and was now found to cause damage in parsley fields and toTropaeolum majus L. (nasturtium) in ornamental gardens.Orobanche amethystea andO. loricata are known as occasional weeds in Europe and were recently found for the first time in Israel.Orobanche amethystea densely populated vetch fields in Israel, andO. loricata was found in ornamental gardens. A key for the identification ofOrobanche species in cultivated areas in Israel is given, based on morphological features.
http://www.phytoparasitica.org posting Jan. 13, 2002. 相似文献
244.
Nickolas?G.?KavallieratosEmail author George?J.?Stathas Christos?G.?Athanassiou George?Th.?Papadoulis 《Phytoparasitica》2002,30(3):231-242
The role of the self-sown shrubsDittrichia viscosa (L.) W. Greuter andRubus ulmifolius Schott as reservoirs of aphid parasitoids was investigated. In the field studies conducted,D. viscosa grew adjacent to crops of durum wheat and barley andR. ulmifolius grew adjacent to cotton. The relative abundance of the parasitoids of(a) Capitophorus inulae (Passerini) onD. viscosa, (b) Rhopalosiphum padi (Linnaeus) on durum wheat and barley,(c) Aphis ruborum (Börner) onR. ulmifolius, and(d) Aphis gossypii Glover on cotton in various parts of Greece, was assessed during the years 1996–2000. In 2000, the fluctuation of parasitization of the above four aphid species was recorded and the action of the aphidophagous predators of the family Coccinellidae was studied. It was observed thatAphidius matricariae Haliday predominated onC. inulae andR. padi in all sampling cases. In contrast,Lysiphlebus fabarum (Marshall) was the dominant species parasitizingA. ruborum onR. ulmifolius andA. gossypii on cotton in Thessaly (central Greece) and Macedonia (northern Greece), whereasLysiphlebus confusus Tremblay et Eady andBinodoxys acalephae (Marshall) were the dominant parasitoid species in Thrace (northern Greece).Coccinella septempunctata Linnaeus was the most abundant coccinellid species on durum wheat, whereasAdonia variegata (Goeze) predominated on cotton. However, coccinellid individuals were scarce on bothD. viscosa andR. ulmifolius. The present study indicated that these two shrubs can be regarded as useful reservoirs of aphid parasitoids. 相似文献
245.
Dry mycelium (DM) of killedPenicillium chrysogenum and its water extract (DME) were used to induce resistance in cotton plants againstFusarium oxysporum f.sp.vasinfectum (Fov). Results showed that the efficacy of either DM or DME in controlling the disease depends on both the concentration and the
mode of application. DM amended to the soil at 0.25–2% (w/w) provided 32–75% protection againstFov. Soil drench with 2–5% DME (w/v) and pre-sowing seed soakage with 5–10% DME provided 51–77% and 28–35% protection against
the wilt disease, respectively, whereas no protection was obtained with foliar sprays of 1–10% DME. DM and its water extract
had no direct antifungal activity on growth ofFov in vitro, suggesting that disease control with DM or DME resulted from the induction of natural defense mechanisms in the cotton plants.
Soil drench with 5% DME was as effective as 2% DM powder in inducing resistance againstFov, implying that the resistance-inducing substances were mostly water-soluble. Four cotton cultivars with various genetic resistance
levels againstFov were tested at the seedling stage: two resistant ‘Pima’ cultivars and two susceptible ‘Acala’ cultivars. The level of protection
achieved in the two susceptible cultivars with DME was equal to, or higher than, that of the two resistant cultivars treated
with water. Innate and induced peroxidase activity in cotyledons or hypocotyls and roots coincided with the level of genetic
resistance and DME-induced resistance, respectively. Based on our results, an integrated control strategy ofFov with both genetic resistance and induced resistance is suggested. 相似文献
246.
Laura H Waitt Christopher K Cebra Susan J Tornquist Christiane V L?hr 《Journal of veterinary diagnostic investigation》2006,18(4):405-408
A 22-year-old pinto mixed breed mare was admitted for evaluation of severe colic signs and gastric reflux. Multiple nonpainful, variably sized hard masses were palpated in the subcutis over the thorax, abdomen, and hindquarters of the horse. The mare was diagnosed with sterile peritonitis and had systemically high gamma-glutamyltransferase, amylase, and lipase. Three days into treatment she became febrile with signs of persistent and mild abdominal discomfort; euthanasia was elected. Necropsy revealed peripancreatitis, pancreatic fibrosis, abdominal steatitis and panniculitis. Panniculitis associated with peripancreatitis has been described in humans and dogs but not in horses. Pathogenic models for this entity are discussed. 相似文献
247.
Hanspeter W Steinmetz Rainer Vogt Sabine K?stner Barbara Riond Jean-Michel Hatt 《Journal of veterinary diagnostic investigation》2007,19(4):382-388
The i-STAT portable clinical analyzer (PCA) was evaluated for performance in avian species. With the EG7+ cartridge, which provided results for hydrogen ion concentration, oxygen tension, carbon dioxide tension, sodium, potassium, ionized calcium, hematocrit, and various calculated parameters, analytical accuracy and precision were tested by comparing obtained values to those of established traditional blood gas and chemistry analyzers. Deming's regression and bias plots were used to compare i-STAT results with those obtained by laboratory professionals using benchtop analyzers. The reliability of the i-STAT PCA with EG7+ cartridges was good, with 0-5.7% system failures in measured values. Regression statistics were good for all blood gas analytes and acceptable for electrolytes and calculated parameters, except for potassium and base excess, for which the regression data or the discrepancy between the methods was too large. The system was reliable and easy to use and had an overall acceptable accuracy in avian species. These features, together with portability and small required blood volumes, make the i-STAT suitable for point-of-care use in critical avian patients, although single values require careful interpretation. 相似文献
248.
249.
Hughes Guyot José Sulon Jean-Fran?ois Beckers Jean Closset Pascal Lebreton Laurent Alves de Oliveira Frédéric Rollin 《Journal of veterinary diagnostic investigation》2007,19(6):643-651
In mammals, thyrotropin, or thyroid-stimulating hormone (TSH), assay is used for the diagnosis of primary hypothyroidism. Hypothyroidism is the most common type of thyroid disorder in cattle. The aim of this study was to develop and validate, under physiologic and pathologic conditions, a radioimmunoassay (RIA) for bovine TSH (bTSH). Double RIA was performed with purified bTSH and specific bovine antiserum. Laboratory validation included research of minimal detection limit, accuracy, and reproducibility. The physiologic validation included a thyrotropin-releasing hormone (TRH) challenge performed on euthyroid cows and a follow-up of bTSH concentration over a 24-hour period. Furthermore, bTSH concentration was assayed in a large population of healthy dairy and beef cows to define reference interval. The pathologic validation was made by assaying bTSH and thyroid hormones on healthy and goitrous newborn calves. The minimum detection limit (MDL) for bTSH assay was 1.3 microU/ml. The recovery was 101% to 106%. The intra- and interassay coefficients of variation (CVs) ranged from 5% to 11% and 11% to 15%, respectively. The RIA covered the whole range of physiologic bTSH values, as shown by bTSH values induced by TRH-challenge. A pulsatile secretion of bTSH was observed, accompanied by a diurnal variation with lower night values than day values. Reference intervals of bTSH ranged from 1.3 to 13.0 microU/ml for beef and dairy breeds. Finally, bTSH easily discriminated goitrous newborn calves from healthy ones, leading to the definition of a cutoff value of 35 microU/ml. The bTSH assay positively reacted to physiologic and pathologic conditions. The accuracy and precision of the RIA were satisfying. 相似文献
250.