全文获取类型
收费全文 | 4876篇 |
免费 | 182篇 |
国内免费 | 3篇 |
专业分类
林业 | 245篇 |
农学 | 202篇 |
基础科学 | 36篇 |
749篇 | |
综合类 | 1268篇 |
农作物 | 223篇 |
水产渔业 | 310篇 |
畜牧兽医 | 1528篇 |
园艺 | 110篇 |
植物保护 | 390篇 |
出版年
2023年 | 22篇 |
2022年 | 26篇 |
2021年 | 62篇 |
2020年 | 73篇 |
2019年 | 94篇 |
2018年 | 91篇 |
2017年 | 83篇 |
2016年 | 91篇 |
2015年 | 65篇 |
2014年 | 85篇 |
2013年 | 183篇 |
2012年 | 259篇 |
2011年 | 339篇 |
2010年 | 188篇 |
2009年 | 145篇 |
2008年 | 331篇 |
2007年 | 337篇 |
2006年 | 376篇 |
2005年 | 321篇 |
2004年 | 331篇 |
2003年 | 304篇 |
2002年 | 302篇 |
2001年 | 58篇 |
2000年 | 35篇 |
1999年 | 48篇 |
1998年 | 50篇 |
1997年 | 28篇 |
1996年 | 36篇 |
1995年 | 36篇 |
1994年 | 30篇 |
1993年 | 36篇 |
1992年 | 31篇 |
1991年 | 31篇 |
1990年 | 30篇 |
1989年 | 37篇 |
1988年 | 27篇 |
1987年 | 32篇 |
1986年 | 21篇 |
1985年 | 27篇 |
1984年 | 32篇 |
1983年 | 25篇 |
1982年 | 23篇 |
1981年 | 26篇 |
1980年 | 23篇 |
1979年 | 15篇 |
1978年 | 17篇 |
1977年 | 18篇 |
1976年 | 19篇 |
1975年 | 16篇 |
1974年 | 24篇 |
排序方式: 共有5061条查询结果,搜索用时 15 毫秒
951.
952.
Landscape Ecology - Soil heterogeneity versus homogeneity patterns are observed within and across urban landscapes at multiple scales. To fully evaluate human-mediated influences on soil properties... 相似文献
953.
Michelle T. Hulin Andrea Vadillo Dieguez Francesca Cossu Samantha Lynn Karen Russell Helen C. Neale Robert W. Jackson Dawn L. Arnold John W. Mansfield Richard J. Harrison 《Plant pathology》2022,71(4):949-965
Bacterial canker is a major disease of stone fruits and is a critical limiting factor to sweet cherry (Prunus avium) production worldwide. One important strategy for disease control is the development of resistant varieties. Partial varietal resistance in sweet cherry is discernible using shoot or whole tree inoculations; however, these quantitative differences in resistance are not evident in detached leaf assays. To identify novel sources of resistance to canker, we used a rapid leaf pathogenicity test to screen a range of wild cherry, ornamental Prunus species and sweet cherry × ornamental cherry hybrids with the canker pathogens, Pseudomonas syringae pvs syringae, morsprunorum races 1 and 2, and avii. Several Prunus accessions exhibited limited symptom development following inoculation with each of the pathogens, and this resistance extended to 16 P. syringae strains pathogenic on sweet cherry and plum. Resistance was associated with reduced bacterial multiplication after inoculation, a phenotype similar to that of commercial sweet cherry towards nonhost strains of P. syringae. Progeny resulting from a cross of a resistant ornamental species Prunus incisa with susceptible sweet cherry (P. avium) exhibited resistance indicating it is an inherited trait. Identification of accessions with resistance to the major bacterial canker pathogens is the first step towards characterizing the underlying genetic mechanisms of resistance and introducing these traits into commercial germplasm. 相似文献
954.
Wernecke Anna Eckert Jakob H. Forster Rolf Kurlemann Nils Odemer Richard 《植物病害和植物保护杂志》2022,129(1):93-105
Journal of Plant Diseases and Protection - Currently, more than 360 spray adjuvants are registered in Germany (September 2021). Unlike plant protection products (PPPs), adjuvants are not subjected... 相似文献
955.
Daniel R. Kidd Megan H. Ryan Timothy D. Colmer Richard J. Simpson 《Grass and Forage Science》2021,76(1):57-71
Serradella (Ornithopus) species are high‐quality pasture legumes that originate from the Mediterranean basin and have been increasingly used in southern Australian temperate grazing systems. They are generally regarded as tolerant of soils with low pH and, by inference, elemental toxicities such as aluminium (Al). No studies have examined the effect of high Al concentrations on the growth of French serradella (Ornithopus sativus Brot.) or newly developed cultivars of yellow serradella (O. compressus L.). Several cultivars/accessions of each species were grown in low ionic‐strength nutrient solutions at pHCa 4.5 containing a range of Al concentrations. Their susceptibility to root growth inhibition by Al was benchmarked against reference species ranging from Al‐sensitive to Al‐tolerant. Most serradella cultivars had moderate‐to‐high Al tolerance in solution culture but one yellow and two French serradella cultivars ranked alongside the Al‐sensitive reference species. A subset of cultivars and reference species were then grown in an Al‐toxic soil to test the validity of the solution culture results; these cultivars spanned the apparent range in Al sensitivity/tolerance indicated by the solution culture experiment. Variation in the relative root length achieved in Al‐toxic solution culture explained ~59% of the variation in the relative root length achieved in the acidic Al‐toxic soil. This result supports the conclusion that Al tolerance varies among serradella and that some cultivars may not thrive in soils with pHCa < 4.5 and elevated extractable Al concentrations. 相似文献
956.
957.
Effects of in vitro brevetoxin exposure on apoptosis and cellular metabolism in a leukemic T cell line (Jurkat) 下载免费PDF全文
Harmful algal blooms (HABs) of the toxic dinoflagellate, Karenia brevis, produce red tide toxins, or brevetoxins. Significant health effects associated with red tide toxin exposure have been reported in sea life and in humans, with brevetoxins documented within immune cells from many species. The objective of this research was to investigate potential immunotoxic effects of brevetoxins using a leukemic T cell line (Jurkat) as an in vitro model system. Viability, cell proliferation, and apoptosis assays were conducted using brevetoxin congeners PbTx-2, PbTx-3, and PbTx-6. The effects of in vitro brevetoxin exposure on cell viability and cellular metabolism or proliferation were determined using trypan blue and MTT (1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan), respectively. Using MTT, cellular metabolic activity was decreased in Jurkat cells exposed to 5 – 10 μg/ml PbTx-2 or PbTx-6. After 3 h, no significant effects on cell viability were observed with any toxin congener in concentrations up to 10 μg/ml. Viability decreased dramatically after 24 h in cells treated with PbTx-2 or -6. Apoptosis, as measured by caspase-3 activity, was significantly increased in cells exposed to PbTx-2 or PbTx-6. In summary, brevetoxin congeners varied in effects on Jurkat cells, with PbTx-2 and PbTx-6 eliciting greater cellular effects compared to PbTx-3. 相似文献
958.
Melissa A. Friedman Lora E. Fleming Mercedes Fernandez Paul Bienfang Kathleen Schrank Robert Dickey Marie-Yasmine Bottein Lorraine Backer Ram Ayyar Richard Weisman Sharon Watkins Ray Granade Andrew Reich 《Marine drugs》2008,6(3):456-479
Ciguatera Fish Poisoning (CFP) is the most frequently reported seafood-toxin illness in the world, and it causes substantial physical and functional impact. It produces a myriad of gastrointestinal, neurologic and/or cardiovascular symptoms which last days to weeks, or even months. Although there are reports of symptom amelioration with some interventions (e.g. IV mannitol), the appropriate treatment for CFP remains unclear to many physicians. We review the literature on the treatments for CFP, including randomized controlled studies and anecdotal reports. The article is intended to clarify treatment options, and provide information about management and prevention of CFP, for emergency room physicians, poison control information providers, other health care providers, and patients. 相似文献
959.
About 19 cultivars, which had originated from backcrosses between F1 LA (Longiflorum × Asiatic) hybrids (2n = 2x = 24) as
female parents and Asiatic cultivars as male parents (2n = 2x = 24), were analyzed with genomic in situ hybridization. 17
of them were triploid (2n = 3x = 36), and two aneuploid (2n = 3x + 1 = 37). The triploid cultivars had resulted from the functional
2n eggs produced by the female parents (F1 hybrids) because first division restitution (FDR) occurred in their meiosis during
megasporogenesis. Similarly, the aneuploid cultivars had originated from viable 2n + 1 eggs. The extra chromosome in cultivar
041555 or 041572 resulted from one univalent or one half-bivalent which might have lagged behind when the sister chromatids
of the other univalents and half-bivalents were segregating during the FDR process in their LA hybrid parents, respectively.
That the majority of cultivars possessed recombinant chromosomes showed that intergenomic recombination might play an important
role during the selection of the cultivars directly from BC1 progenies. That five cultivars of the 15 recombinant cultivars
only had reciprocal recombinant chromosomes and 10 cultivars had non-reciprocal recombinant chromosomes indicates that the
latter are more important. Because 9 of the 10 non-reciprocal recombinant cultivars possessed substitutions for recombinant
segments, it also indicated that such substitutions could be an important source for the genetic variation in the sexual triploid
BC1 progenies. In such cases there was a potential for the expression of the recessive genes of the backcross parent in a
nulliplex (aaa) condition in the substituted segments. Genetic variation resulting from such nulliplex loci might have played
a role in the selection of some of the cultivars. 相似文献
960.