首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   175篇
  免费   4篇
林业   13篇
农学   13篇
基础科学   5篇
  43篇
综合类   17篇
农作物   15篇
水产渔业   9篇
畜牧兽医   46篇
园艺   4篇
植物保护   14篇
  2023年   1篇
  2022年   10篇
  2021年   2篇
  2020年   2篇
  2019年   1篇
  2018年   3篇
  2017年   9篇
  2016年   5篇
  2015年   2篇
  2014年   8篇
  2013年   13篇
  2012年   10篇
  2011年   9篇
  2010年   5篇
  2009年   11篇
  2008年   7篇
  2007年   11篇
  2006年   3篇
  2005年   2篇
  2004年   4篇
  2003年   6篇
  2002年   3篇
  2001年   4篇
  2000年   3篇
  1999年   3篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1995年   3篇
  1992年   1篇
  1991年   3篇
  1989年   1篇
  1988年   1篇
  1986年   4篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   2篇
  1980年   4篇
  1979年   3篇
  1978年   3篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1969年   1篇
  1967年   2篇
排序方式: 共有179条查询结果,搜索用时 29 毫秒
31.
Abstract

Nitrogen (N) applied through urea is essential for rice crops and usually it is the most yield-limiting nutrient in irrigated rice production around the world. A field experiment was conducted to evaluate the effect of nitrogen levels (0, 90,120, and 150?kg?ha?1) on the nutritional quality of straw and grain of rice varieties, PR 111, PR 122, and Pusa 44. In rice straw, significant interaction between nitrogen levels and all proximate components was observed. Increase in nitrogen level increased the crude protein by 69.23% (dry matter basis) whereas the neutral detergent fiber, acid detergent fiber, and cellulose content decreased by 7.82%, 11.18%, and 14.16%, respectively. In rice grain, crude protein content, starch content, and gel consistency were positively related to increase in nitrogen levels. Therefore, increase in nitrogen fertilization led to improved nutritive quality of both straw and grain for use as feed resource and human consumption, respectively.  相似文献   
32.
Diversification of rice-wheat cropping system may improve the productivity and sustainability of agricultural production in the Indo-Gangetic plane region (IGPR), but the choice of alternative sequences to be used requires integrated assessment of various crop sequences. A long-term field experiment was initiated during 2000–01 on sandy loam soil at Banaras Hindu University, Varanasi, India to assess 10 rice-based cropping sequences – rice-wheat, rice-chickpea, rice-wheat-green gram, rice-wheat-Sesbania (green manure), rice-mustard-green gram, rice-lentil-cowpea (fodder), rice-pea, rice-lentil + mustard (3:1)-cowpea (fodder), rice-maize (cob) + vegetable pea (1:1)-cowpea (fodder) and rice-potato-green gram in randomized block design with four replications. The data contained in this paper are for the year 2002–03 and 2003–04. Substitution of rice-wheat with 300% intensity cropping sequences particularly with rice-potato-green gram resulted in maximum production cost but gave the highest system productivity, net return, benefit:cost ratio, production efficiency, profitability and energy productivity. Inclusion of summer grain/fodder legume or Sesbania for green manuring improved the content of soil organic matter. The soil P status was positively affected in all the sequences and particularly those with summer crops. Decline in soil available K in all the sequences indicated inadequacy of present recommended rate of fertilizer K to all the component crops in different sequences.  相似文献   
33.
The effect of varying hydrogel (0, 0.5, and 1.0% w/w) supply on some agro-physiological properties, such as dry matter, nutrient contents, chlorophyll contents, proline content, and ionic balance of bean plants in different salt sources and stress due to doses were investigated. Plants were treated with eight salt sources [sodium chloride (NaCl), sodium sulfate (Na2SO4), calcium chloride (CaCl2), calcium sulfate (CaSO4), potassium chloride (KCl), potassium sulfate (K2SO4), magnesium chloride (MgCl2), magnesium sulfate (MgSO4)] and four concentrations (0, 30, 60, and 120 mM doses) for 60 days in a growth media. Salt type, doses, and hydrogel (HG) affected the soil electrical conductivity. Soil salinity affected the parameters considered, and changed the nutrient balance of plants. High salt concentration caused substantial reduction in plant growth. Different salt concentrations negatively affected plant dry weight. The highest decrease of plant root dry weight was obtained with NaCl application followed by Na2SO4, CaCl2, CaSO4, MgCl2, MgSO4, KCl, and K2SO4, and similarly NaCl, Na2SO4, CaCl2, CaSO4, KCl, K2SO4, MgCl2, and MgSO4 in root dry weight. Total chlorophyll and nitrate contents of plants decreased with increasing salt doses, and the lowest value was obtained for NaCl application. Proline contents of plants were increased with increasing salt doses, and the highest value was obtained with the NaCl application. The effects of salt concentrations in nitrogen (N), potassium (K), and phosphorus (P) content of plants were significant. The presence of salt in the growth medium induced an important decrease the macro nutrient of the root and shoot part of plant such as N, P, K, calcium (Ca), and magnesium (Mg) content, but the N and P content of root and shoot part of the plant were increased with increasing of the HG application doses. The highest N and P increases were obtained with the 1.0 HG application for all salt types for both the root and shoots of plants. The HG added to saline soil significantly improved the variables affected by high salinity and also increased plant N and P, reduced soil electricity conductivity, nitrate, proline, and electrolyte leakage of plants, enhanced plant root and shoot dry weight by allowing nutrients and water to release to the plant as needed. The results suggested that HG has great potential for use in alleviating salinity stress on plant growth and growth parameters in saline soils of arid and semi-arid areas. This HG appears to be highly effective for use as a soil conditioner in vegetable growing, to improve crop tolerance and growth in saline conditions. It is intended to confirm the results of these studies by field trials.  相似文献   
34.
Water, Air, &; Soil Pollution - The bacterial communities in the intestinal tracts of earthworm were isolated by culture-dependent approaches. In total, 72 cultures were isolated and purified...  相似文献   
35.
2-(2′,4′-Dibromophenoxy)-4,6-dibromophenol isolated from the marine sponge Dysidea granulosa (Bergquist) collected off the coast of Lakshadweep islands, Indian Ocean, exhibited potent and broad spectrum in-vitro antibacterial activity, especially against methicillin resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), vancomycin resistant Enterococci (VRE), vancomycin sensitive Enterococci (VSE) and Bacillus spp. Minimal inhibitory concentration (MIC) was evaluated against 57 clinical and standard strains of Gram positive and Gram negative bacteria. The observed MIC range was 0.117–2.5 μg/mL against all the Gram positive bacteria and 0.5–2 μg/mL against Gram negative bacteria. The in-vitro antibacterial activity observed was better than that of the standard antibiotic linezolid, a marketed anti-MRSA drug. The results establish 2-(2′,4′-dibromophenoxy)-4,6-dibromophenol, as a potential lead molecule for anti-MRSA and anti-VRE drug development.  相似文献   
36.
Five methods that employed very different testing principles and procedures for assessing gluten quality were compared for 33 North American soft red and white wheats. The three methods analyzed flour (alveograph work, lactic acid solvent retention capacity, and mixograph peak time) and two methods employed ground wheat meal (Glutomatic gluten index and SDS sedimentation volume). Compared against the normalized mean of all five assessments, the ability of the assessment methods to evaluate gluten quality decreased in the order: alveograph work, lactic acid solvent retention capacity, mixograph peak time, Glutomatic gluten index, and SDS sedimentation volume. The methods utilizing flour were substantially superior predictive methods; however, the two meal‐based methods could be sufficient for early generation screening when flour is not available.  相似文献   
37.
38.
The benefits of co-management depend on cooperation between a government agency and stakeholders. However, neither cooperation nor the deliberative processes through which it develops, have been a focus of past co-management research. The paper explores the consensus-building criteria that influence the development of cooperation among and between local stakeholders and a government agency using a comparative case study of two Local Citizens Committees in Ontario, Canada. The study uses cognitive mapping and network analysis techniques to identify key consensus-building criteria, which are grouped into common and idiosyncratic key consensus-building criteria of the two LCCs. All key consensus-building criteria are analysed to generate an explanation of the criteria that influence the development of cooperation. The paper concludes with five lessons regarding the development of cooperation that have implications for consensus-building and co-management theory.  相似文献   
39.
Brucella melitensis Rev 1 organisms were salt-extracted and the cell surface proteins (BCSPs) were found to be mainly 39-42 kDa (group 2 porin proteins) in addition to 31.6, 32.5, 58.5 and 14.7 kDa proteins. DEAE-Sephadex anion-exchange column chromatography of BCSPs yielded fraction 1, which contained one major protein (39.8-42.0 kDa) and a minor protein (31.6 kDa). All these proteins were found to be immunogenic by Western blotting. Fraction 1 along with monophosphoryl lipid A and trehalose dicorynomycolate adjuvants as well as BCSPs alone induced significant (p < or = 0.05) protection in BALB/c mice. Both these immunizing agents produced almost equivalent protection to live B. melitensis Rev 1 vaccine at 15 and 30 days post challenge. Lymphocyte stimulation test as well as delayed-type hypersensitivity reaction revealed that both these preparations induced cell-mediated immune response. These preparations also induced humoral immune response as indicated by indirect ELISA. Neither of the immune responses was significantly less (p < or = 0.05) than that with live B. melitensis Rev 1 vaccine, except that their duration was short.  相似文献   
40.
A 10-year-old neutered male Airedale Terrier was evaluated for inappetance, weight loss, and lameness. Multiple myeloma was diagnosed based on bone marrow plasmacytosis, multiple lytic bone lesions, and hyperglobulinemia with a clonal gammopathy on serum protein electrophoresis. Splenic plasmacytosis, and retinal lesions consistent with hyperviscosity syndrome also were found. Temporary responses to 2 different chemotherapy protocols (melphalan and prednisone, and cyclophosphamide and prednisone) were seen, with remission of clinical signs and a decrease in the biclonal gammopathy but no resolution of the splenic mass. Eventual return of clinical signs led to euthanasia at 175 days postdiagnosis. Necropsy examination confirmed multiple myeloma involving bone marrow and spleen, and glomerulonephritis. An immunoglobulin-A (IgA) gammopathy was demonstrated by immunoelectrophoresis; biclonality was ascertained by immunofixation electrophoresis. The clonal components consisted of intact Ig with a heavy chain of the a class and a light chain of undetermined class. To our knowledge, this is the first report of undimerized biclonal gammopathy in a dog caused by a single heavy chain class involving IgA.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号