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   225篇
  免费   24篇
林业   13篇
农学   5篇
基础科学   4篇
  65篇
综合类   11篇
农作物   17篇
水产渔业   42篇
畜牧兽医   80篇
园艺   6篇
植物保护   6篇
  2023年   4篇
  2022年   5篇
  2021年   1篇
  2020年   4篇
  2019年   11篇
  2018年   16篇
  2017年   17篇
  2016年   15篇
  2015年   4篇
  2014年   15篇
  2013年   17篇
  2012年   10篇
  2011年   14篇
  2010年   14篇
  2009年   9篇
  2008年   8篇
  2007年   8篇
  2006年   10篇
  2005年   10篇
  2004年   6篇
  2003年   5篇
  2002年   4篇
  2001年   2篇
  1999年   2篇
  1998年   4篇
  1997年   5篇
  1996年   2篇
  1995年   1篇
  1994年   4篇
  1993年   5篇
  1992年   1篇
  1991年   4篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1984年   1篇
  1981年   2篇
  1979年   1篇
  1971年   1篇
排序方式: 共有249条查询结果,搜索用时 968 毫秒
11.
The hypothesis was tested that certain physico-chemical characteristics might be used as indicators of total starch availability and rate of starch availability of milled rice. Milled unparboiled (uPB) and parboiled (PB) rice samples (n=93) were characterized using standardized methods of physical tests and chemical analyses and anin vitromethod was used for measuring the rate of starch digestion on a subsample of rice (n=26). The rice varieties were dominated by medium long, bold rice grain with high amylose rice and intermediate gelatinization temperature (GT), but a wide range in all characteristics was measured. Small amounts of resistant starch (RS) were measured in the cooked rice, indicating virtually complete starch availability. The RS of PB rice (0·4 g/100 g rice as eaten) was significantly (P<0·004) higher than the RS of uPB rice (0·1 g/100 g) however. The rate of starch digestion was significantly affected by both variety and parboiling. The starch digestion index (SDI) values of the PB samples (mean value 73·7) were significantly (P<0·001) lower than those of the uPB samples (mean value 79·0). The apparent amylose content (AC) was the strongest determinant for SDI in both uPB and PB rice. The widths and shapes of the raw grains and the elongation after cooking were correlated significantly with SDI values for the uPB rice, while the relatively mild parboiling procedure followed in this study eliminated this correlation. The minimum cooking times were correlated significantly with the SDI values in the uPB samples.  相似文献   
12.
13.
Protoplasts were isolated from young inflorescence-derived suspension cultures of a japonica rice cultivar ‘Taipei 177’. The isolated protoplasts which were cultured either in liquid, agar on Sea plaque agarose underwent sustained division. Maximum plating efficiency of 1.06% occurred in a medium containing macroelements of KM, microelements and vitamins of B5, 0.5 % Sea plaque agarose, 1.0 mg/l of 2,4-D, and glucose as an osmotic stabilizer. Green and albino plants were regenerated from the protocalli in MS semisolid medium containing 4 mg/l BAP, 0.5 mg/l NAA and 500 mg/l casein hydrolysate (MS18–2).  相似文献   
14.
Specialty chemicals based on renewable resources are desirable commodities due to their eco-friendly nature and "green" product characteristics. These chemicals can demonstrate physical and chemical properties comparable to those of conventional petroleum-based products. Suitably functionalized amines in the triacylglycerol structure can function as an antioxidant, as well as an antiwear/antifriction agent. In addition, the amphiphilic nature of seed oils makes them an excellent candidate as base fluid. The reaction of amine and epoxidized seed oils in the presence of a catalyst almost always leads to different intra/intermolecular cross-linked products. In most cases, the triacylglycerol structure is lost due to disruption of the ester linkage. Currently, there is no reported literature describing the aminolysis of vegetable oil without cross-linking. Here the epoxy group of the epoxidized soybean oil has been selectively reacted with amines to give amine-functionalized soybean oil. The optimization procedure involved various amines and catalysts for maximum aminolysis, without cross-linking and disruption of the ester linkage. Diethylamine and ZnCl2 were found to be the best. NMR, IR, and nitrogen analysis were used to characterize the products.  相似文献   
15.
Bromodeoxyuridine (BrdUrd) treatment of the prolactin nonproducing subclone of GH cells (rat pituitary tumor cells) induces amplification of a 20-kilobase DNA fragment including all of the prolactin gene coding sequences. This amplified DNA segment, which is flanked by two unamplified regions, thus designates a unit of BrdUrd-induced amplified sequence. Cloned DNA segments, 10.3 kilobases long, from the 5' end of the rat prolactin gene of BrdUrd-responsive and -nonresponsive cells, were ligated to the thymidine kinase gene of herpes simplex virus type 1 (HSV1TK), and the hybrid DNA was transferred to thymidine kinase-deficient mouse fibroblast cells by transfection. The HSV1TK gene and the rat prolactin gene were amplified together in drug-treated transfectants carrying the hybrid DNA HSV1TK gene and rat prolactin gene of BrdUrd-responsive GH cells. These results suggest that the 10.3-kilobase DNA segment at the 5' end of the rat prolactin gene of BrdUrd-responsive GH cells carries the information for drug-induced gene amplification (amplicon) and that another gene, such as the HSV1TK gene, is also amplified when the latter is placed adjacent to this segment.  相似文献   
16.
Femtosecond laser pulses and coherent two-phonon Raman scattering were used to excite KTaO3 into a squeezed state, nearly periodic in time, in which the variance of the atomic displacements dips below the standard quantum limit for half of a cycle. This nonclassical state involves a continuum of transverse acoustic modes that leads to oscillations in the refractive index associated with the frequency of a van Hove singularity in the phonon density of states.  相似文献   
17.
Conversion of methane to higher hydrocarbons by its low-temperature activation without forming undesirable carbon oxides is of great scientific and practical importance. Methane can be highly activated, yielding high rates of conversion to higher hydrocarbons and aromatics (10 to 45 percent) at low temperatures (400° to 600°C), by its reaction over H-galloaluminosilicate ZSM-5 type (MFI) zeolite in the presence of alkenes or higher alkanes. The methane activation results from its hydrogen-transfer reaction with alkenes.  相似文献   
18.
The present study was to assess informativeness and efficiency of three different molecular markers for genetic diversity among 24 Citrus and its relative species. Sixty one SSR, 33 SRAP and 24 CAPS-SNP markers were used to evaluate the level of polymorphism and discriminating capacity. A total of 596, 656 and 135 polymorphic amplicons were observed in SSR, SRAP and CAPS-SNP markers with average polymorphism information content (PIC) of 0.97, 0.98 and 0.89, respectively. High levels of polymorphism were recorded for SSR and SRAP compared with CAPS-SNP markers. The highest correlations (r = 0.930) were obtained between SSR and SRAP markers, whereas SSR and CAPS-SNP were poorly correlated (r = 0.833). Cluster analysis was performed to construct dendrograms using UPGMA. And the dendrogram from SSR data was most congruent with the general dendrogram. These findings provide basis for future efficient use of these molecular markers in the genetic analysis of Citrus and its relatives.  相似文献   
19.
20.
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