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181.
Roth JA Hibbard B Frank DE Kesl L Robb EJ 《Veterinary therapeutics : research in applied veterinary medicine》2002,3(3):347-353
Holstein steer calves received a single injection of Miglyol (Sasol Chemical Industries, Ltd.) subcutaneously as a placebo, dihydroheptaprenol (DHP) (4 mg/kg) emulsified with lecithin subcutaneously, DHP in solution in Miglyol (4 mg/kg) subcutaneously, or DHP in solution in Miglyol (4 mg/kg) intranasally. The DHP emulsified in lecithin emulsion administered subcutaneously caused a substantial increase in body temperature, total leukocyte count, total neutrophil count, neutrophil cytochrome-c reduction, and neutrophil iodination 24 hours after administration and, for some of the parameters, at 48 hours. The DHP formulation in Miglyol did not have any of these effects when administered subcutaneously or intranasally. The carrier and formulation of DHP apparently have major effects on the biologic activity of DHP. 相似文献
182.
Robinson JE Birch RA Taylor JA Foster DL Padmanabhan V 《Domestic animal endocrinology》2002,23(1-2):43-52
It has long been recognised that steroids can have both organisational and activational effects on the reproductive neuroendocrine axis of many species, including the sheep. Specifically, if the ovine foetus is exposed to testosterone during a relatively short 'window' of in utero development (from approximately day 30-90 of a 147 day pregnancy) the neural mechanisms regulating gonadotrophin releasing hormone (GnRH) secretion become organised in a male-specific manner. In post-natal life the consequences of foetal androgen exposure are sexually differentiated responses of the GnRH neuronal network to activation by factors such as photoperiod and ovarian steroid hormones. Studies in the gonadectomized lamb have demonstrated that elevated concentrations of oestrogen (E) are unable to trigger a preovulatory-like GnRH surge in the male and the androgenized ewe lamb. Further, these animals have markedly reduced sensitivity to the inhibitory actions of progesterone on tonic GnRH release compared with normal ewes. The reasons for these abnormal steroid feedback mechanisms may reside in sexually dimorphic inputs to the GnRH neurone, including those from oestrogen-receptive neurones in the arcuate nucleus that synthetize the neuropeptide, neurokinin B (NKB). The consequences of in utero androgen exposure are reflected in a progressive and dramatic impairment of fertility in the ovary-intact ewe. 相似文献
183.
The Virginia-Maryland Regional College of Veterinary Medicine (VMRCVM) agreed to perform outcomes assessment (OA) as part of the accreditation review process for the American Veterinary Medical Association (AVMA). Nine OA instruments were developed and validated by a 20-member accreditation committee. The instruments were also pre-tested by a subset of the target population. The instruments were for alumni one to five years post-graduate, alumni 6-15 years post-graduate, faculty, staff, DVM students, employers of veterinarians, referring veterinarians using the Blacksburg campus, and referring veterinarians using the Leesburg campus. In addition, data were used from OA surveys previously done for the Office of Research and Graduate Studies. Data from the surveys were incorporated into each of the 11 Essentials for Accreditation required by the AVMA. The process of OA provided a comprehensive assessment of the many aspects of the operation of the college. An important follow-up to the OA process is use of data to enhance and/or re-prioritize existing programs. 相似文献
184.
185.
ABSTRACT Five areas in urban Miami were identified to study the spread of Xanthomonas axonopodis pv. citri to determine if the practice of removing exposed citrus trees within 38.1 m of trees affected by citrus canker was adequate to curtail further bacterial spread. To accomplish this, 18,769 trees in dooryards were surveyed, geo-referenced by differential global positioning systems (GPS), and assayed for disease severity, age of infection, citrus cultivar, location of infection in tree, and canopy size. For each tree, the date the tree became infected was estimated and used to separate trees into contiguous 30-day categories. For each area studied, distance measurements between focal trees and newly infected trees were calculated for various temporal periods of 30, 60, 90, and 120 days in duration, corresponding to intervals of inspection survey. A visual basic application was used to calculate the distances between each newly diseased tree and all prior focal trees. The nearest distance was used because it was considered the most conservative estimate possible. It is therefore likely to be an underestimate of spread but is a good estimate of the minimum possible distances of spread. For the first four 30-day periods among the five study areas, calculated maximum distances of spread ranged from 12 to 3,474 m, indicating a broad continuum of distance for bacterial spread was possible. Disease increased during the first two-thirds of the time studied and reached an asymptote due to dry conditions in the final one-third of the duration of the study. Cross correlation analysis indicated that disease was best visualized 107 days following rainstorms with wind. Analysis of regional spatial point patterns was performed temporally for each 30-day period via a modified Ripley's K-function. Spatiotemporal analyses between periods over areas larger than previously examined were accomplished via spatiotemporal semivariogram analysis. These methods in combination demonstrated rapid increases in range of spatial dependency and range of spatiotemporal dependency for all study sites. This corresponded to rapid spread of disease across the regions studied in response to rainstorms with wind followed by a "filling in" of disease on remaining noninfected susceptible trees through time by less intense rain events. A stochastic quadratization technique demonstrated that disease incidence and disease severity were not greatly affected by urban host density but were positively correlated to host susceptibility within local 0.25-km(2) quadrats. 相似文献
186.
Abundance and richness are the two fundamental components of speciesdiversity. They represent two distinct types of variables of which the formerisadditive when aggregated across scales while the latter is nonadditive. Thisstudy investigated the changes in the spatial patterns of abundance andrichnessof tree species across multiple scales in a tropical rain forest of Malaysiaandtheir variations in different regions of the study area. The results showedthatfrom fine to coarse scales abundance had a gradual and systematic change inpattern, whereas the change in richness was much less predictable and ahotspot in richness at one scale may become acoldspot at another. The study also demonstrated that differentmeasures of diversity variation (e.g., variance and coefficient of variation)can result in different or even contradictory results which further complicatedthe interpretation of diversity patterns. Because of scale effect the commonlyused measure of species diversity in terms of unit area (e.g.,species/m2) is misleading and of little use in comparing speciesdiversitybetween different ecosystems. Extra care must be taken if management andconservation of species diversity have to be based on information gathered at asingle scale.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
187.
In association with industry, an extensive database has been established on measurements of sea louse counts on farmed Atlantic salmon for the years 1996 to 2000 from 33 Scottish fish farms. These data include extensive counts on the sea louse species, Lepeophtheirus salmonis, at various stages of the life cycle and in particular the chalimus and mobile stages. There has been considerable speculation as to what factors might affect the abundance of sea lice, much of which is based on limited evidence. Our analyses show that there is tremendous variation in sea louse infestation patterns from year to year, whereas stock type, geographical region and coastal exposure do not appear to affect mean levels of abundance. In contrast, treatments lead to pronounced cycles of sea louse infestation with peaks and troughs at 3-week intervals, and these interventions are important if the sea louse levels on fish are to be controlled. There was no evidence of water temperature affecting the mean annual abundance of sea louse infestation. 相似文献
188.
189.
Brian J McCluskey Brandy Burgess James Glover Hailu Kinde Sharon Hietala 《Journal of veterinary diagnostic investigation》2006,18(3):296-299
The use of sentinel chickens in establishing the negative status of commercial poultry flocks depopulated due to exotic Newcastle disease (END) is considered to be an economically beneficial process. However, the costs and benefits of using sentinel chickens in noncommercial operations are in question. The objective of this study was to use sentinel chickens to evaluate whether adequate cleaning and disinfection coupled with an appropriate time period without susceptible poultry species on the premises would eliminate END virus from a noncommercial poultry operation and preclude the need for placement of sentinels in previously infected operations before declaring them free of virus. Noncommercial poultry operations were selected from the 2002 to 2003 END outbreak database. Operations included in the study had one or more isolations of END virus (ENDV) from cloacal or oropharyngeal swabs of birds on the premises. A total of 546 birds were placed on 53 premises. All sentinel birds sampled after placements were negative by virus detection methods and serologic tests. Results of this study indicate that time and the application of appropriate cleaning and disinfection procedures will adequately mitigate the risk of viable virus persisting in noncommercial poultry operations. In the future, this information may eliminate the need for sentinel bird placement to ensure virus free status of premises before repopulation, thereby decreasing the costs of END eradication. 相似文献
190.
This case report documents an unusual tracheal foreign body (a moth) in Congo African grey parrot (Psittacus erithacus erithacus). Gross postmortem signs and histopathology results are presented. A discussion of the peculiar avian anatomy that may have contributed to the aspiration of the moth is provided. 相似文献