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21.
    
Deforestation principally to establish cattle pastures has created large expanses of land dominated by exotic grass prior to the establishment of the Cerro Blanco Protected Forest in Ecuador. A dry forest restoration program was carried out from 2008 to 2017. Tree planting sites were cleared in parallel lines through abandoned pasture and secondary vegetation using manual labor. Native tree species were produced in a nursery on site and used in yearly plantings during the rainy season. A total of 637 hectares were planted at an average stocking density of 1,000 trees per hectare. Growth data was collected from trees planted in nine sites from 2008 to 2017. Mortality rates were determined from a sample of 400 trees of twenty-two species. Survival of all species was greater than 50%. Ten species had survival rates greater than 90%. Vitex gigantea, with high survival rates, also had significantly greater growth rates than the other species (p < 0.0001) and showed the greatest yearly accumulation of total carbon (2.07 Kg C yr ?1 stem?1). Other species with high growth rates were Cordia alliodora and Centrolobium ochroxylum. This restoration program demonstrates that the dry forest restoration with timely maintenance and protection from fire and grazing is possible with intensive tree planting of native species.  相似文献   
22.
    
A field trial was conducted to study Mycoplasma hyopneumoniae (Mh) infection dynamics by nested polymerase chain reaction (nPCR) and serology in pigs of a farm affected by enzootic pneumonia (EP). Moreover, correlation of Mh detection at different respiratory tract sites with presence of EP gross and microscopic lung lesions was assessed. These parameters were studied and compared between vaccinated (two doses at 1 and 3 weeks of age versus one dose at 6 weeks of age) and non-vaccinated pigs. Animals were monitored from birth to slaughter by nPCR from nasal swabs and by serology. From 3 to 22 weeks of age, an average of three pigs per treatment and per batch were necropsied (n = 302). The remaining pigs were sent to the slaughter (n = 103). Nasal, bronchial and tonsillar swabs were taken from the necropsied/slaughtered pigs; gross and microscopic EP-suggestive lung lesions were also assessed. Single and double vaccination resulted in earlier seroconversion and higher percentage of Mh seropositive pigs compared to control group. At slaughter, double vaccinated pigs showed lower percentage of EP-compatible gross lung lesions and lower Mh prevalence at upper respiratory tract sites (nasal cavity and tonsil) than control pigs.  相似文献   
23.
This study looked at measurement of endotoxaemia as a tool in determining prognosis and probable response to treatment in scouring lambs. One hundred eighty-three lambs in the first 15-20 days of life, from eight Merino sheep farms located in the region of La Serena, south-west Spain, were used in this experiment. Scouring and normal/control lambs were selected following a clinical examination, the scouring group was further divided into subgroups, specifically those that did or did not survive 72 h following treatment. At the time of the clinical examination, faecal and blood samples were taken. Faecal culture and commercial faecal antigen tests for detection of enteropathogens in faeces and serum endotoxin measurement using chromogenic lymulus amoebocyte lysate (LAL) were carried out. Scouring lambs received 0.07 mg/kg liveweight halofuginone once a day for 3 days, a single oral dose of 0.20 mg/kg liveweight of spectinomycin and oral rehydration fluid. The pathogens isolated were Cryptosporidium spp. and Escherichia coli. The case fatality rate was 51% in the scouring lambs. Postmortem findings were consistent with enterotoxigenic E. coli infection. The concentration of endotoxin was 0.18 +/- 0.12 ng/ml in the control group, 0.35 +/- 0.17 ng/ml in the surviving lambs and 0.46 +/- 0.14 ng/ml in the non-surviving lambs. Significant differences between groups were found. Case fatality rate of the scouring lambs with endotoxaemia below 0.30 ng/ml was 0%, while it was 100% above 0.50 ng/ml. These results may be utilized as a prognostic indicator in lambs affected by E. coli and Cryptosporidium that will help aid in decision-making as to whether to treat a lamb or not based on its chances of survival.  相似文献   
24.
The review deals with three books focused on two questions dealing with a single problem: how human cultures and crop cultures are interrelated? The two questions dealt with are: Is there a conflict between the evolution of cultivated plants and the present trend of our cultural (including social, economical, ideological or political) evolution? If yes, what can be done to diminish this conflict? The three books focused on these questions deal with (1) growing number of endangered crops on global scale (Khoshbakht and Hammer, Threatened Crop Species Diversity. Shahid Beheshti University Press, Teheran 2010), (2) massive erosion of locally and regionally important crop varieties and associated traditional knowledge followed by collapse of whole agroecosystems and landscapes on a country scale (Antofie, A red list of crop plant varieties for Romania—Lista rosie a varietatilor plantelor de cultura din Romania. Publ. House Lucian Blaga Univ., Sibiu 2011), and (3) the growing number of endangered human communities (ethnic, cultural and linguistic islands) which preserved for centuries many valuable genetic resources (Hammer et al. 2011).  相似文献   
25.
By use of headspace SPME sampling and a PLOT column, on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta(13)C(VPDB) and delta(18)O(VSMOW) values of ethanol in authentic (n = 14) and commercial tequila samples (n = 15) as well as a number of other spirits (n = 23). Whereas with delta(13)C(VPDB) values ranging from -12.1 to -13.2 per thousand and from -12.5 to -14.8 per thousand similar variations were found for 100% agave and mixed tequilas, respectively, the delta(18)O(VSMOW) data differed slightly within these categories: ranges from +22.1 to +22.8 per thousand and +20.8 to +21.7 per thousand were determined for both the authentic 100% agave and mixed products, respectively. The data recorded for commercial tequilas were less homogeneous; delta(13)C(VPDB) data from -10.6 to -13.9 per thousand and delta(18)O(VSMOW) values from +15.5 to +22.7 per thousand were determined in tequilas of both categories. Owing to overlapping data, attempts to differentiate between white, rested, and aged tequilas within each of the two categories failed. In addition, discrimination of tequila samples from other spirits by means of delta(13)C(VPDB) and delta(18)O(VSMOW) data of ethanol was restricted to the products originating from C(3) as well as C(4)/CAM raw materials.  相似文献   
26.
Microbial processes are key elements in determining the productivity of mangroves, and reductions in these processes reflect the loss of microbial biodiversity and function due to fabricated disturbances. Because nitrogen is a major limiting nutrient for the productivity of these ecosystems, the goal of this study was to determine profiles of inorganic nitrogen combined with several environmental parameters, all in relation to the degree of long-term hydraulic impairment of a tropical, monospecific black mangrove (Avicennia germinans) forest that showed degradation ranging from total loss of mangrove cover to no disturbance. N2-fixation, oxygen levels, and nitrite contents decreased significantly with the severity of the disturbance, and almost null levels were reached in the completely degraded zone, whereas salinity achieved very high values. Concomitantly, total N, ammonium, and P contents and ammonia volatilization increased significantly. Pore-water temperature and pH increased moderately. Other soil physical properties (sand, silt, clay, organic matter, and total C), which varied among the sampling sites, were not correlated with the level of disturbance. Principal component analyses, including environmental and biological parameters, suggested that the most significant finding was the considerable loss of N2-fixation with increasing impairment, which was concomitant with significant increases in volatilization of ammonia and salinity. The results show that microbial N-cycling processes are highly sensitive to salinity and to man-made disturbances that modify the water level and flow.  相似文献   
27.
Journal of Crop Science and Biotechnology - Coffee (Coffea Arabica L.) is threatened by biotic and abiotic stresses. Nevertheless, the breeding of Arabica coffee is restricted due to its low...  相似文献   
28.
High dilution rates have been documented as detrimental for boar spermatozoa, shortening their lifespan (Centurion et al. 2003, Biol Reprod 69: 640–646). Addition of seminal plasma (SP) to semen extenders, or selenium (Se) and vitamin E (VE) in diet of boars could increase motility of highly diluted spermatozoa (HDS). The aim of this work was to evaluate the effect of seminal plasma on sperm motility of HDS from boars feed with Se and VE. Sixteen 12 month-old boars were designed to one of four dietary treatments: (i) control, Se 0 ppm–VE 0 IU/kg; (ii) Se 0–VE 250; (iii) Se 0.5–VE 250 and (iv) Se 0.5–VE 0. Boars were treated for 8 weeks before semen collection. Sperm rich fractions from each boar were diluted to 5 × 106 sperm/ml in PBS medium and incubated at 37°C with or without 10% SP. The measurements were done at 0, 2 or 5 h. Data were analyzed as a mixed model for a factorial design [2 (Se) × 2 (VE) × 2 (SP) × 3 (h)]. Percentage of sperm motility (PSM) increases significantly (p < 0.001) with addition of Se (81.3 ± 1.52), VE (81.0 ± 1.62) and SP (81.5 ± 1.57) vs control (73.4 ± 1.61). There was significant interaction Se × VE (p < 0.001) and Se × VE × SP (p < 0.05) in PSM. However, PSM was affected significantly by time (0 h 83.4 ± 1.92; 2 h 80.7 ± 1.92 and 5 h 67.9 ± 1.92; p < 0.001). There was significant interaction SP × Time (p < 0.05) in PSM. These results indicate that Se, VE and SP improve seminal viability. Addition of 10% of SP maintains PSM at least during 5 hours.  相似文献   
29.
    
  • 1. An ecosystem analysis was developed focusing on resource exploitation and biodiversity conservation for the Northern Gulf of California. The main tools employed were a trophic ecosystem model and time dynamic simulations.
  • 2. The ecosystem was represented by an Ecopath model that included 34 functional groups, from primary producers to top predators. It included relevant species in the area such as commercially important shrimp (e.g. Litopenaeus stylirostris) and highly endangered species (Phocoena sinus and Totoaba macdonaldi).
  • 3. Temporal simulations of changing fishing effort allowed the evaluation of fishing impact on the ecosystem components and, particularly, on protected species. Formal optimization methods were applied with the purpose of searching viable temporal patterns of fishing effort that might minimize social, economic and conservationist conflicts in the area.
  • 4. The results of those simulations showed the capability of the model to represent reference temporal series of relative biomass. The search for viable fishing strategies resulted in effort allocation consistent with those proposed by other studies; that is, a decrease in the industrial shrimp fleet (35–65%), a decrease in the gillnet fishing fleet (52–57%), and an increase of the artisanal shrimp fishery (63–222%).
  • 5. The main conflicts in the Northern Gulf of California seem to take place between social and conservation interests, while the economic and ecological benefits seem to be relatively independent. The next steps towards conflict resolution and ecosystem management should consider the design and operation of MPAs already established in the region.
Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
30.
Journal of Crop Science and Biotechnology - To achieve food security and increase crop productivity in a sustainable way, keeping soil fertile and balanced fertilization is vital. Soil fertility...  相似文献   
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