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Does public infrastructure affect state output? This paper uses both a Cobb-Douglas and a translog production function to examine the impact of public infrastructure spending on state output. Like labor and private capital, the stock of public capital is considered to be an input into the production process. The data are based on Alicia Munnell's work and were provided by the Federal Reserve Bank of Boston. Unlike many of the earlier studies employing Ordinary Least Squares (OLS) techniques, this analysis employs estimating methods that take advantage of the longitudinal nature of the data set. While these methods lend support to the public capitol hypothesis, there is evidence that studies relying on OLS have reported a coefficient on public capital that is upward biased. This paper, which controls for heterogeneity in the data, finds the coefficient on public capital to be smaller than that presented in previous studies. This finding has important policy implications. It indicates that while investment in public capital may have a positive impact on the private sector, this impact will be much smaller than predicted by previous studies. 相似文献
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Yun Sang CHO Sang Eun LEE Jong-Tae WOO Jinsik OH Hwan Won CHOI Jin Hyeok KWON Jeong-Tae KIM Gunwoo HA Sukchan JUNG 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2020,82(11):1631
Bovine tuberculosis (bTB) is a zoonosis caused by Mycobacterium bovis. Test-and-cull protocols and gross pathological examinations of abattoir animals as well as milk pasteurization have been implemented to prevent the spread of tuberculosis from animals to humans worldwide. Despite the importance of precise and rapid diagnostic tests, conventional methods including intradermal skin tests and γ-interferon assays are limited by the high rate of false-negative results for cattle in the late infectious stage and due to laborious and time-consuming procedures. Therefore, antibody detection methods such as enzyme-linked immunosorbent assay (ELISA) are urgently needed to supplement the established approaches and expand the diagnostic window. This study was conducted to develop a bTB ELISA by evaluating recombinant and native proteins and various assay parameters. We produced recombinant MPB70 and SahH (M70S) and a native 20-kDa protein (20K) and optimized the ELISA protocol. The 20K ELISA showed 94.4% sensitivity and 98.2% specificity with an optimal sample-to-positive ratio cut-off of 0.531. The sensitivity and specificity of M70S ELISA were 94.4% and 97.3%, respectively, with an optimal sample-to-negative ratio cut-off of 1.696. Both assays showed acceptable diagnostic efficiency and could be used for bTB diagnosis in combination with established methods for herd screening and to expand the diagnostic window. 相似文献
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The behavior of soil organisms inhabiting soil pore spaces can be influenced by soil compression, which can affect their avoidance behavior to pollutants. In this study, we aimed to evaluate the effect of soil compression on the avoidance behavior of Allonychiurus kimi (Collembola) to heavy metals cadmium and copper. Initially, to assess the applicability of the avoidance test guideline of the International Organization for Standardization (ISO) developed for Folsomia candida, we investigated the avoidance behavior of A. kimi to cadmium and copper in an artificial soil with a loose structure (bulk density of 0.25 g cm-3), the porous texture of which was sufficiently loose to enable A. kimi to move between pore spaces. The effect of soil compression on the avoidance behavior of A. kimi to both metals was evaluated in compressed soil (bulk density of 0.64 g cm-3) with a uniformly compressed soil surface, and avoidance behavior was investigated at 24-h intervals over a 120-h period. Given that A. kimi is unable to burrow into compressed soil, the compressed soil test can minimize the effects of differences in soil factors, such as soil porosity and bulk density, on the behavior of this collembolan. In the artificial soil, a statistically significant avoidance behavior of A. kimi was observed at cadmium and copper concentrations greater than 50 and 200 mg kg-1, respectively, thereby indicating the applicability of the ISO avoidance test guidelines for A. kimi. When compared at the same exposure time point, the avoidance response to both metals in compressed soil was less sensitive than that in uncompressed soil. In addition, we observed differences in the effects of metals on avoidance response in the compressed soil over time, with the effect of cadmium increasing with time and the effect of copper showing the opposite trend. Overall, we found that soil compression can affect the avoidance behavior of A. kimi to cadmium and copper, and we discussed the advantages and limitations of using compressed soil for assessments of pollutant toxicity. 相似文献
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DAVID A. BOMMARITO MICHAEL S. KENT KIM A. SELTING CAROLYN J. HENRY JIMMY C. LATTIMER 《Veterinary radiology & ultrasound》2011,52(2):207-212
Canine nasal tumors are typically treated with radiation therapy but most patients develop local recurrence. Our purpose was to evaluate tumor and normal tissue response to reirradiation in nine dogs. The median dose delivered with the first protocol was 50 Gy (range 44–55 Gy) and the median fraction number was 18 (range 15–20). For the second protocol, the median dose was lower intentionally, median of 36 Gy (range 23–44 Gy), without changing the median fraction number of 18 (range 14–20) to avoid late effects. The median time between protocols was 539 days (range 258–1652 days). Median survival was 927 days (95% confidence interval [CI] 423–1767 days). Median time to progression following the first and second courses was 513 days (95% CI 234–1180 days) and 282 days (95% CI 130–453 days), respectively. These were not significantly different (P=0.086). The qualitative response assessment was better for the first course compared with the second (P=0.018). Severity and timing of skin, mucous membrane, and ocular effects were similar for early side effects between the two courses (P>0.05 for all comparisons). All dogs experienced some late side effects, with two out of nine being classified as severe. These severe effects were blindness in each dog, possibly related to tumor recurrence. Reirradiation of canine nasal tumors resulted in a second clinical remission in eight of nine dogs, although the second response was less complete. Acute and late effects for seven of nine patients were not life threatening, indicating that reirradiation of canine nasal tumors may be a viable treatment option after recurrence. 相似文献
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