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51.
We investigated heat tolerance at the reproductive stage in six spring‐type B. rapa accessions and one B. juncea accession as a control. Plants were subjected to two temperature treatments for seven days in controlled environmental rooms, beginning one day before the first open flower on the main stem inflorescence. The high‐temperature treatment ranged from 25 °C to 35 °C during 16 h light and 25 °C during 8 h dark. The control temperature treatment was set at 23 °C during 16 h light and 15 °C during 8 h dark. Soil moisture was maintained at close to field capacity to avoid drought stress. Main stem buds that emerged during the treatment period were tagged, and pod and seed production was recorded at each reproductive node. Leaf temperature depression and leaf conductance increased in the high‐temperature treatment which indicated that plants were not drought stressed. A leafy vegetable type of B. rapa from Indonesia was the most tolerant to high temperature, as defined by its ability to set seed equally well in the control and high‐temperature treatments, followed by an oilseed type from Pakistan. Pollen viability remained above 87 % in all accessions and treatments. We conclude that bud number and length, and pod number produced under high temperatures, might provide a useful preliminary screen for high‐temperature tolerance and that B. rapa may be a valuable source of heat tolerance in canola (B. napus). 相似文献
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53.
C. R. Tyler J. J. Nagler T. G. Pottinger M. A. Turner 《Fish physiology and biochemistry》1994,13(4):309-316
Virgin female rainbow trout, Oncorhynchus mykiss, were unilaterally ovariectomised at various stages of ovarian development to investigate the effect of the removal of one
ovary on subsequent recruitment and growth of follicles in the remaining ovary. The right ovary was removed from groups of
12–15 fish, 12, 7 and 4 months before they were due to ovulate, and the gonadosomatic index and follicle number and size determined
just prior to ovulation. There were no differences in fecundity or follicle size in fish unilaterally ovariectomised at 12
and 7 months prior to ovulation compared to the controls. However, in the females unilaterally ovariectomised 4 months prior
to ovulation, the remaining ovary either had the normal number of follicles for a single ovary but of a significantly larger
size than follicles in the controls, or alternatively had almost 70% more than the normal number of vitellogenic follicles
but comprising two distinctly different size populations. Differences in plasma oestradiol-17β concentrations at the final
sample were seen only in females unilaterally ovariectomised 4 months prior to ovulation, where the levels were significantly
lower than both the sham operated and control fish (p < 0.05).
These data show that in the rainbow trout, complete compensatory ovarian hypertrophy following unilateral ovariectomy can
occur throughout a major part of ovarian development, but that follicle recruitment is limited to stages up to (and therefore
fecundity is determined by) mid-vitellogenesis. 相似文献
54.
Y. M. Guo N. C. Turner S. Chen M. N. Nelson K. H. M. Siddique W. A. Cowling 《Journal of Agronomy and Crop Science》2015,201(4):267-279
Brassica rapa L. is a genetically diverse parent species of the allotetraploid species, oilseed rape (B. napus) and a potential source of drought tolerance for B. napus. We examined the effect of a 13‐day drought stress period during the early reproductive phase, relative to a well‐watered (WW) control, on subsequent growth and development in nine accessions of B. rapa and one accession of Brassica juncea selected for their wide morphological and genetic diversity. We measured leaf water potential, stomatal conductance, water use, and leaf and bud temperatures during the stress period and aboveground dry weight of total biomass at maturity. Dry weight of seeds and reproductive tissue were not useful measures of drought tolerance due to self‐incompatibility in B. rapa. The relative total biomass (used as the measure of drought tolerance in this study) of the 10 accessions exposed to drought stress ranged from 47 % to 117 % of the WW treatment and was negatively correlated with leaf‐to‐air and bud‐to‐air temperature difference when averaged across the 13‐day stress period. Two wild‐type (B. rapa ssp. sylvestris) accessions had higher relative total and non‐reproductive biomass at maturity and cooler leaves and buds than other types. We conclude that considerable genotypic variation for drought tolerance exists in B. rapa and cooler leaves and buds during a transient drought stress in the early reproductive phase may be a useful screening tool for drought tolerance. 相似文献
55.
L F Karcher J L Le Net B F Turner T J Reimers B C Tennant 《The Cornell veterinarian》1990,80(2):153-162
An 18-year-old Appaloosa mare was examined because of squamous cell carcinoma of the vulva, anorexia with pronounced weight loss, and hypercalcemia. The tumor had developed rapidly over a period of 3 months and externally extended ventrally involving the perineum and the dorsal aspect of the udder. Necropsy examination demonstrated a large primary squamous cell carcinoma of the vulva, perineum, and mammary gland with metastases to the supramammary, sublumbar, deep inguinal, and mediastinal lymph nodes. No gross renal lesions were observed and, histologically, there was only mild vacuolation of renal tubular epithelium. Based on the normal concentration of serum parathyroid hormone, the absence of evidence of hypervitaminosis D, and normal renal function, a diagnosis was made of hypercalcemia of malignancy or pseudohyperparathyroidism. The mechanism responsible for hypercalcemia was not determined, but the histologic type of the neoplasm and the clinical course suggested possible production of a humoral hypercalcemic factor by the neoplasm, similar to that demonstrated in certain types of human squamous cell carcinoma. 相似文献
56.
J. Turner 《The Journal of small animal practice》1990,31(7):367-367
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59.
After rising steadily between 1954 and 1968, the percentage of all bachelor's degrees awarded in the arts and sciences declined dramatically. These swings cannot be explained by demographic variables; however, they have been affected by changes in the academic profiles of educational institutions that were in turn related to trends in enrollment. Even more important have been the changing choices of fields of study made by men and women (particularly in the case of the humanities), in part as a consequence of widening opportunities for women. The flight from the arts and sciences now appears to be over, and in the future gender-related variables can be expected to have less impact on the distribution of degrees conferred. 相似文献
60.
A passage line of a spontaneous hamster fibrosarcoma is contaminated by the virus. of lymphocytic choriomeningitis. Tumors from animals receiving implants when newborn contain high titers of infectious lymphocytic-choriomeningitis virus and complement-fixing antigen, and hamsters receiving implants when weanlings develop high titers of complement-fixing antibody against lymphocytic-choriomeningitis virus. In contrast with the specific reactions of tumorous hamsters to the initiating virus in virus-induced tumors, the development of complement-fixing antibody to lymphocytic-choriomeningitis virus does not depend on the development of tumors. Infant hamsters bearing the tumor have a generalized subclinical infection and seem able to spread virus to other hamsters and to humans. 相似文献