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61.

Background  

The effects of lighting on the human circadian system are well-established. The recent discovery of 'non-visual' retinal receptors has confirmed an anatomical basis for the non-image forming, biological effects of light and has stimulated interest in the use of light to enhance wellbeing in the corporate setting.  相似文献   
62.
The diet selection, made by twelve dry and twelve lactating spring‐calving Salers beef cows at the end of the grazing season on an extensively grazed natural mountain pasture in central France, was compared. Sward structure, selection bites, daily grazing time and digestibility of the diet were measured in mid‐October (P1) and mid‐November (P2). Live weights were measured twice monthly throughout the experiment. Daily milk production was assessed in the week before the grazing behaviour measurements. Lactating cows grazed more selectively than dry cows: they took more bites on green patches (0·20 vs. 0·13 of total bites, P < 0·01; Jacob's selectivity index: 0·13 vs. ?0·25, P < 0·001), which is consistent with the higher overall nitrogen concentration in faeces (18·1 vs. 17·3 g kg?1 DM, P < 0·05). Lactating cows tended to slightly increase their daily grazing time compared with dry cows (on average 9·9 vs. 9·5 h, P = 0·07) and grazed faster in mid‐November (74 vs. 69 bites min?1, P < 0·05). The lactating cows lost more live weight (?24 vs. ?12 kg cow?1, P < 0·05) between P1 and P2. A positive correlation was found between consumption of green patches by lactating cows and their daily milk production in P2 (r = 0·574, P = 0·05), whereas no correlation occurred between individual milk production and liveweight loss. Dry cows were less selective, which supports management practices that promote the use of cows with low requirements on extensively grazed pastures in late season.  相似文献   
63.
The aim of the current study was to determine the possible effects of progestagen oestrous synchronization on vascular endothelial growth factor (VEGF) expression during sheep luteogenesis and the peri‐implantation period and the relationship with luteal function. At days 9, 11, 13, 15, 17 and 21 of pregnancy, the ovaries from 30 progestagen treated and 30 ewes cycling after cloprostenol injection were evaluated by ultrasonography and, thereafter, collected and processed for immunohistochemical evaluation of VEGF; blood samples were drawn for evaluating plasma progesterone. The progestagen‐treated group showed smaller corpora lutea than cloprostenol‐treated and lower progesterone secretion. The expression of VEGF in the luteal cells increased with time in the cloprostenol group, but not in the progestagen‐treated group, which even showed a decrease between days 11 and 13. In progestagen‐treated sheep, VEGF expression in granulosa‐derived parenchymal lobule capillaries was correlated with the size of the luteal tissue, larger corpora lutea had higher expression, and tended to have a higher progesterone secretion. In conclusion, the current study indicates the existence of deleterious effects from exogenous progestagen treatments on progesterone secretion from induced corpora lutea, which correlate with alterations in the expression of VEGF in the luteal tissue and, this, presumably in the processes of neoangiogenesis and luteogenesis.  相似文献   
64.
This study was designed to evaluate the effect of single layer centrifugation (SLC) and subsequent cold storage on stallion sperm capacitation‐like status and acrosome reaction. Three stallions were included in the study, with three ejaculates per stallion. The samples were examined 4, 24 and 72 h after collection, extension and SLC, with storage at 6°C. Sperm capacitation‐like status was investigated using the fluorescent dye chlortetracycline (CTC). There was no difference in capacitation‐like status between colloid‐selected and non‐selected spermatozoa. Sperm motility decreased significantly during cold storage, whereas the proportion of apparently capacitated spermatozoa increased. There was no change in the proportion of acrosome‐reacted spermatozoa. In conclusion, SLC through Androcoll?‐E does not adversely affect the capacitation‐like status of stallion spermatozoa, although it did increase with time during cold storage.  相似文献   
65.
We have investigated the speciation and distribution of iron (Fe) and aluminium (Al) between minerals and organic species in A and B horizons of two Aluandic Andosols with X‐ray diffraction, thermal analyses, visible diffuse reflectance and Fourier transform infrared (FTIR) spectroscopies, together with selective and total chemical extractions. The two Aluandic Andosols of the Nilgiri Highlands (south India) have formed at the expense of intensively weathered lateritic formations of the Eocene. Data revealed that Al and Fe were predominantly stored in end‐weathering products of laterites, mainly as gibbsite and Fe (hydr)oxides in B horizons of the Aluandic Andosols. These secondary minerals are gradually replaced by organo‐metallic complexes in the topsoil A horizons exhibiting andic properties. We then indicate that formation of the organo‐metallic complexes results from weathering of the dominant crystalline Al‐ and Fe‐(hydr)oxides mediated by the organic ligands and complexation of the polyvalent metals following the accumulation of organic matter. Such weathering and complexation mechanisms are therefore similar to those recently ascribed to deferralitization and the formation of freely drained Umbric Podzols (Humus‐Podzols) in the upper Amazon Basin. In the present case, large supplies of both Al‐ and Fe‐bearing minerals provide large metal:carbon ratios that prevent the mobility of the organo‐metallic complexes and induce the formation of Aluandic Andosols rather than Podzols.  相似文献   
66.
Chlamydia psittaci was detected by PCR in the lung and equine foetal membranes of two aborted equine foetuses and one weak foal from two different studs in Victoria, Australia. The abortions occurred in September 2019 in two mares sharing a paddock northeast of Melbourne. The weak foal was born in October 2019 in a similar geographical region and died soon after birth despite receiving veterinary care. The detection of C. psittaci DNA in the lung and equine foetal membranes of the aborted or weak foals and the absence of any other factors that are commonly associated with abortion or neonatal death suggest that this pathogen may be the cause of the reproductive loss. The detection of C. psittaci in these cases is consistent with the recent detection of C. psittaci in association with equine abortion in New South Wales. These cases in Victoria show that C. psittaci, and the zoonotic risk it poses, should be considered in association with equine reproductive loss in other areas of Australia.  相似文献   
67.
ABSTRACT To further understand the development of esca disease in grapevine, its physiological impact on plants grown in the vineyard was characterized, focusing mainly on photosynthesis. For this purpose, the state of the photosynthetic apparatus was evaluated in symptomatic and asymptomatic leaves in esca-infected grape plants, and wood carbohydrates stored in annual canes were assayed. In symptomatic leaves, esca greatly affected grapevine physiology. Foliar symptoms were associated with both stomatal closure and alteration of the photosynthetic apparatus as revealed by (i) a decrease in CO(2) assimilation, transpiration, and a significant increase in intercellular CO(2) concentration; (ii) a strong drop in both the maximum fluorescence yield and the effective Photosystem II quantum yield; and (iii) a reduction of total chlorophyll but a stable carotenoid content. On symptomatic canes, all these variables were affected more on leaves with symptoms than without symptoms, suggesting a gradation in photosynthesis disruptions in the plant according to the degree of symptom severity. In addition, canes of symptomatic plants had reduced carbohydrate reserves during the winter rest, whether they exhibit symptoms or not. The following year, the lower pool of reserves may contribute to a significant decrease in plant development, as well as a global loss in plant vigor.  相似文献   
68.
69.
The Miribel canal is a former arm of the Rhône embanked between 1848 and 1857 over a length of 18 km to improve navigation at low discharges. The impact of this was a hydraulic tilting of the long profile characterised by 4 m of degradation upstream and 4-6 m of aggradation of bedload downstream. This phenomenon increased downstream flooding. Since 1937 a diversion dam has controlled upstream water input, thus reducing the transit of the pebble bedload. However, excessive harvesting of sands and gravels occurred between 1970 and 1980, resulting in a general lowering of the river bed and the accompanying water table with ecological consequences in the alluvial plain and for water supply. This development made it all the more necessary to obtain knowledge about the bedload discharges passing through the Miribel canal, and more broadly about the hydraulic conditions as functions of the varying discharge. Calculation of shear stresses and grain size measurements on the lateral bars after several floods in 1989-90 show that movement of bed-material is initiated at a discharge of 440 m3 · s−1 (equalled or exceeded 40 days · year−1), and becomes general at 550 m3 · s−1 (equalled or exceeded 30 days · year−1). Transport discharge is thus relatively frequent and involves distal fluvio-glacial deposits composed of fine-grained materials. Potential transport calculated by the Meyer-Peter formula is around 60,000 t · year−1 for the range of discharges between 440 and 850 m3 · s−1. For these discharge values, the canal experiences a loss of materials without replacement from upstream; for higher rates of discharge, the floodgates let through an unknown quantity of materials which partially make up the loss. Gravel harvesting ceased in 1991 but the diversion dam will have to be operated in a different way in order to increase the input of bedload into the canal.  相似文献   
70.
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