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81.
Kaleczyc J Pidsudko Z Franke-Radowiecka A Sienkiewicz W Majewski M Lakomy M Timmermans JP 《Polish journal of veterinary sciences》2004,7(3):199-201
The present study investigated the chemical coding of neurons in the celiac-superior mesenteric ganglion complex supplying the normal (n=4) and inflamed (n=4) ileum (chemically-induced inflammation) in juvenile pigs using retrograde tracing combined with immunohistochemistry. Ileum-projecting neurons (IPN) were predominantly distributed in the left and right superior mesenteric pools of the ganglion. The majority of them were adrenergic (tyrosine hydroxylase-positive) and also contained neuropeptide Y, somatostatin or galanin. No clear-cut differences in the distribution and chemical coding of IPN were found between normal and inflamed pigs. However, in the inflamed group, the density of peptidergic, IPN-associated nerve fibres was higher than that found in the control group. 相似文献
82.
Arthropod predators are abundant in turfgrass systems, and they play an important role in managing pests. Understanding the vertical distribution of predation is critical to developing cultural strategies that enhance and conserve predatory services. However, little is known on how the predation is vertically distributed within the turfgrass canopy. Thus, the objective of this study was to determine the vertical distribution of predation within the turfgrass canopy. Clay models were used to emulate the general appearance of Noctuidae caterpillars, to estimate the predatory activity. The choice and no-choice experiments were conducted by placing clay models at 2.54, 5.08, and 7.62 cm from the thatch surface and denoted as lower, intermediate, and upper levels, respectively, within turfgrass canopy. The predator-mediated impressions, paired mark, scratch, deep cut mark, deep distortion, prick, dent, stacked surface impression, scooped mark, granulation, and U-shaped mark, were identified on clay models. The incidence and severity of impressions were significantly greater on clay models placed at the lower canopy level than on those placed at the intermediate and upper canopy levels in the choice and no-choice experiments (P < 0.05). Thus, predators are more likely to find their prey at the soil level. This information can be used to refine management strategies, such as mowing height and insecticide use for effectively managing soil-borne and foliar-feeding arthropod pests and beneficial arthropods. 相似文献
83.
Distribution of light and heavy fractions of soil organic carbon as related to land use and tillage practice 总被引:10,自引:0,他引:10
Mass distributions of different soil organic carbon (SOC) fractions are influenced by land use and management. Concentrations of C and N in light- and heavy fractions of bulk soils and aggregates in 0–20 cm were determined to evaluate the role of aggregation in SOC sequestration under conventional tillage (CT), no-till (NT), and forest treatments. Light- and heavy fractions of SOC were separated using 1.85 g mL−1 sodium polytungstate solution. Soils under forest and NT preserved, respectively, 167% and 94% more light fraction than those under CT. The mass of light fraction decreased with an increase in soil depth, but significantly increased with an increase in aggregate size. C concentrations of light fraction in all aggregate classes were significantly higher under NT and forest than under CT. C concentrations in heavy fraction averaged 20, 10, and 8 g kg−1 under forest, NT, and CT, respectively. Of the total SOC pool, heavy fraction C accounted for 76% in CT soils and 63% in forest and NT soils. These data suggest that there is a greater protection of SOC by aggregates in the light fraction of minimally disturbed soils than that of disturbed soil, and the SOC loss following conversion from forest to agriculture is attributed to reduction in C concentrations in both heavy and light fractions. In contrast, the SOC gain upon conversion from CT to NT is primarily attributed to an increase in C concentration in the light fraction. 相似文献
84.
C. Rusterucci Z. Zhao K. Haines D. Mellersh M. Neumann R.K. Cameron 《Physiological and Molecular Plant Pathology》2005,66(6):120
As plants mature it has been observed that some become more resistant to normally virulent pathogens. The ability to manifest the Age-Related Resistance (ARR) response in Arabidopsis to Pseudomonas syringae pathovars tomato (Pst) coincided with the transition to flowering in plants both delayed and accelerated in the transition to flowering. ARR was also associated with a change in PR-1 gene expression, such that young plants expressed PR-1 abundantly at 3 days post inoculation (dpi) while mature plants expressed much less. The Arabidopsis ARR response requires SA accumulation via isochorismate synthase (ICS1) [24]. ICS1 was expressed one dpi with virulent and avirulent Pst in both young and mature plants. The ARR response was also effective versus avirulent Pst providing an additional 4-fold limitation in bacterial growth. Arabidopsis ARR was found to be ineffective against two necrotrophs, Erwinia carotovora subspecies carotovora (bacterium) and Botrytis cinerea (fungus) and one obligate biotroph, Erysiphe cichoracearum (fungus). However, mature wild type, SA-deficient sid2 and NahG plants supported little growth of the obligate biotrophic oomycete, Peronospora parasitica. Therefore ARR to P. parasitica appears to be SA-independent, however the level of ARR resistance was somewhat reduced in these mutants in some experiments. Thus, there may be numerous defence pathways that contribute to adult plant resistance in Arabidopsis. 相似文献
85.
N. N. Kakareka Z. N. Kozlovskaya Yu. G. Volkov T. I. Pleshakova 《Russian Agricultural Sciences》2008,34(4):227-229
Infection of pepper caused by an isometric virus with a 30 ± 3 nm virion diameter is revealed. The thermal inactivation point of virus in jimsonweed sap is 75–80°C, longevity in vitro 3 days at 25°C, and dilution end-point of virus 10?3–10?4. The capsid of the virus contains two types of protein with molecular mass 55 and 12.6 kDa. A distant antigenic relatedness to the tobacco ringspot virus of the genus Nepovirus is shown. 相似文献
86.
The use of doubled haploids improves the efficiency of cultivar development in many crops and can be helpful in genetic and molecular studies. The major problem with this approach is the low efficiency of green plant regeneration. We describe here an efficient method for inducing embryos and regenerating green plants directly from isolated microspores of durum wheat cv. ‘Jennah Khetifa’. Tillers from donor plants were pretreated in 0.3 m mannitol and were stored at 4°C at various times: 3, 5, 6, 7, 8, 10 and 12 days. Our results showed clearly that the novel pretreatment combined mannitol 0.3 m and cold for 7 days had a strong effect on the number of embryos produced and regenerated green plants. Under this condition 13 475 mature embryos were produced from 2 693 500 microspores. Moreover, 85 green plants were obtained. High green plants regeneration frequency was recorded. As an average 11.55 green plants were produced per 100 000 microspores (about the equivalent of six plants per spike). Therefore, this study showed clearly that our results are the best ones published until now in durum wheat. 相似文献
87.
There is no knowledge about the differential capacity of canola genotypes to take up potassium (K) and produce dry matter
under conditions of low soil K availability. Hence, 84 canola genotypes were screened for K efficiency in the glasshouse.
Plants were grown in sealed pots containing K-responsive, sandy soil without or with K added. Twelve genotypes were selected
for advanced screening in the glasshouse in a different K-responsive soil. Genotypes with a mean K efficiency ratio (the ratio
of shoot dry weight at deficient and adequate K supply) greater than one standard error above or below the median genotype
value were classified as K-efficient or K-inefficient, respectively. There were significant differences between genotypes
in the K efficiency ratio in both screening experiments, indicating that genotypes responded differently to K availability.
In the initial screening experiment, 19 genotypes were rated as K-efficient and nine genotypes rated as K-inefficient based
on the K efficiency ratio. In the advanced screening experiment with 12 genotypes, three genotypes were rated as K-efficient
and two as K-inefficient. Genotypes Wesbarker and Rainbow were K-efficient and Genkai K-inefficient in both experiments. Correlation
of the K efficiency ratio with (i) shoot K content in the initial and advanced screening and (ii) shoot K concentration in
the advanced screening, indicates that the observed differences in K efficiency were due to genotypic differences in both
the uptake and the utilization of K. K-efficient genotypes have a potential to improve canola yields on soils with low K availability. 相似文献
88.
89.
Field trials in two cropping seasons and two locations in central China were conducted on 60 Chinese autumn‐sown wheat varieties to assess their partial resistance to powdery mildew. Mean levels of disease severity ranged from close to 0 to more than 90%. The method of inoculation and the location in which trials were conducted affected the relative performance of the varieties, but these effects were much smaller than the main effect of variety. The area under the disease progress curve was highly correlated with final disease severity, but both were poorly correlated with apparent infection rate. Disease severity was regressed against frequencies of virulence in the Blumeria graminis (syn. Erysiphe graminis) f sp. tritici populations in the trial plots. A vertical distance (D) from the mean mildew severity to the fitted line was calculated for each variety and was used to quantify partial resistance. Five of the 60 varieties, ‘Hx8541’, ‘E28547’, ‘Chuan1066’, ‘Zhe88pin6’ and ‘Lin5064’, consistently expressed relatively low levels of disease despite high frequencies of virulence in the pathogen and had consistently high D‐values. They may therefore have good levels of partial resistance. 相似文献
90.
B.I.G. Haussmann D.E. Hess B.V.S. Reddy S.Z. Mukuru M. Kayentao H.G. Welz H.H. Geiger 《Euphytica》2001,122(2):297-308
The parasitic weed Striga hermonthica (Del.) Benth. seriously limits sorghum [Sorghum bicolor (L.) Moench] production in Sub-Saharan Africa. As an outbreeder, S. hermonthica is highly variable with an extraordinary capacity to adapt to different hosts and environments, thereby complicating resistance
breeding. To study genotype x environment (G x E) interaction for striga resistance and grain yield, nine sorghum lines, 36
F2 populations and five local checks were grown under striga infestation at two locations in both Mali and Kenya. Mean squares
due to genotypes and G x E interaction were highly significant for both sorghum grain yield and area under striga severity
progress curve(ASVPC, a measure of striga emergence and vigor throughout the season). For grain yield, the entry x location-within-country
interaction explained most of the total G x E while for ASVPC, entry x country and entry x location-within-country interactions
were equally important. Pattern analysis (classification and ordination techniques) was applied to the environment-standardized
matrix of entry x environment means. The classification clearly distinguished Malian from Kenyan locations for ASVPC, but
not for grain yield. Performance plots for different entry groups showed differing patterns of adaptation. The ordination
biplot underlined the importance of entry x country interaction for ASVPC. The F2 derived from the cross of the striga-resistant line Framida with the striga-tolerant cultivar Seredo was the superior entry
for both grain yield and ASVPC, underlining the importance of combining resistance with tolerance in striga resistance breeding.
The observed entry x country interaction for ASVPC may be due to the entries' different reactions to climatic conditions and
putative differences in striga virulence in Mali and Kenya.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献