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排序方式: 共有1943条查询结果,搜索用时 15 毫秒
921.
J .Silvertown和D .Charlesworth的《简明植物种群生物学》(IntroductiontoPlantPopulationBiology)第四版 ,已经由BlackwellPublishing(Oxford)公司于 2 0 0 1年出版发行了。其中文译本也随即由李博教授等人译出 ,并由高等教育出版社于 2 0 0 3年 3月出版发行。这是中国生态学界的一件可喜可贺的大事。它的付梓 ,除了可以为中国广大热切关注生态学发展的人们及时送来营养丰富的最新精神滋养而外 ,还鲜明地昭示出中国的生态学者跟踪和把握世界生态学发展前沿的意识正在变得更加敏锐和准确。种群在具有层次结构的整个生态学的理论框架中…  相似文献   
922.
河南若干小麦品种籽粒戊聚糖含量的初步研究   总被引:11,自引:0,他引:11  
1999-2000年对河南省8个有代表性的小麦品种的戊聚糖进行了测定,不同品种戊聚糖的平均含量变化范围为6%-9%。不同品种和不同生态条件下小麦籽粒戊聚糖含量均有很大差异。5个试点小麦籽粒戊聚糖的平均含量与千粒重,降落值均成负相关关系(r=-0.83,r=-0.31),而与蛋白质的含量却呈正相关关系(r=0.35)。说明戊聚糖含量与生态因素有很大关系,采用Eberhart-Russell模型对小鼠戊聚糖含量的稳定性进行分析。发现豫麦34是戊聚糖含量较理想的品种。  相似文献   
923.
李凤山 《生物多样性》2002,10(4):393-398
于1996年1月对西藏中南部越冬黑颈鹤的食性和谷物性食物的可获得性进行了研究。青梨(Hordeum vulgare),春小麦(Triticum spp.),冬小麦(Triticum spp.)是该地区的3种主要作物。对黑颈鹤粪便的分析表明,越冬黑颈鹤取食大量的农作物,尤其是小麦散落从粒,而冬小麦苗仅上鹤类食物组成的很小一部分。秋收后的翻耕,放牧等农业活动影响地面上作物残物(种子,叶,秆或根)及谷粒残物(裸粒,穗稃)的数量,农地翻耕掩埋了大部分的作物残物。未翻耕青梨地与小麦地上的作物残物覆盖比值相似。谷物残物的密度在未翻耕的小麦地上最大,为了最大限度地增加黑颈鹤的冬季食物来源,减少人为活动对黑颈鹤的干扰,我们建议:在秋收后不要翻耕河流两侧的青梨地和小麦地;在冬小麦种植地区,冬小麦应仅仅种植在主要公路两侧。  相似文献   
924.
Summary This study presents the first comparative analysis of the effect of four different cytokinins, applied to different lentil (Lens culinaris Medik.) explants in four different concentrations. with regard to the regeneration of shoots and roots of the pulse crop. The variables explant, phytohormone and concentration were all found to be highly significant. Mature seed explants showed the highest shoot regeneration over all the phytohormones and concentrations tested. Thidiazuron (TDZ) and benzyladenine (BA) showed a higher number of regenerated shoots than kinetin (KIN) and zeatin (ZEA); an increase from 1.25 μM to 10 μM of any cytokinin in general doubled the number of shoots regenerated. The average length of regenerated shoots was found to be inversely proportional to the number of shoots regenerated. TDZ and BA were found to inhibit root development more than KIN and ZEA. The highest root regeneration frequency was obtained from shoots regenerated on media containing 1.25 μM ZEA. The study concludes that in order to obtain whole plants it is best to regenerate shoots on media containing the cytokinins KIN or ZEA at low concentrations, in order to be able subsequently to regenerate roots.  相似文献   
925.
The aim of this study was to determine whether increasing a lipogenic nutrient (beet pulp; BP) at the expense of a glucogenic nutrient (barley grain; BG) can decrease the body condition score (BCS) of fat cows in late lactation. Eighteen lactating Holstein cows were used in a randomized complete block design. The cows were 171 ± 16.3 days in pregnancy, 289 ± 35.1 days in milk and 4.12 ± 0.351 BCS at the beginning of the study. Cows were assigned randomly to one of three dietary treatments containing: (1) 234.7 g/kg BG (without BP), (2) 148.7 g/kg BG (86 g/kg BP), or (3) 62.7 g/kg BG (172 g/kg BP). By adding BP, the starch (190.2, 151.0, and 123.3 g/kg DM) and NDFom (308.6, 319.3, and 337.9 g/kg DM) levels in the TMR changed. Substituting BG by BP didn’t affect yield of milk protein and lactose, but milk fat level and milk energy output increased as BP replaced BG. Adding BP caused BCS and back fat thickness to reduce. Plasma glucose and cholesterol decreased as BP substituted for BG. Results suggest that inclusion of BP in diets of fat cows during late lactation may slightly reduce BCS, and increase milk fat and energy levels, with no effect on milk yield.  相似文献   
926.
瘿椒树(Tapiscia sinensis Oliv.)为我国特有的珍稀保护植物,5月开花受精以后,以裸露的子房(未发育的幼果)渡过漫长的冬季,次年9月果实成熟,其有性生殖过程持续17个月之久,并发展出一套独特的越冬策略;子房壁和花托表面形成类似周皮的次生保护组织,花托膨大并向下延伸包围果柄,与裸露的子房形成了一个“越冬复合体”。子房壁和膨大花托的基本组织中积累大量淀粉粒,有些细胞形成粘液腔,或发育成含簇晶或单宁的异细胞。瘿椒树特殊的越冬策略体现了它在长期的演化过程中对环境的适应。  相似文献   
927.
杀雄剂SQ-1诱导小麦雄性不育花粉粒差异蛋白质组学研究   总被引:3,自引:0,他引:3  
采用固相pH梯度/SDS-PAGE双向凝胶电泳对经杀雄剂SQ-1处理和未处理的小麦(Triticum aestivum)成熟期花粉总蛋白质进行了分离, 银染显色, 获得了分辨率和重复性较好的双向电泳图谱. 通过PDQuest 2DE图像软件的分析, 在等电点4~7之间可识别350个以上较为清晰的蛋白质点, 其中差异表达明显的蛋白质点数为21个. 将11个差异点采用基质辅助激光解析电离飞行时间质谱进行了肽质量指纹图谱分析, 采用Mascot软件在Swiss-prot数据库查询, 鉴定出了7个蛋白质, 它们分别是液泡转化酶、动力蛋白轻链TCTEX-1、锰超氧化物歧化酶、果糖-1,6-二磷酸醛缩酶、抗坏血酸过氧化物酶、凝集素蛋白激酶和一种未知功能的蛋白. 对已知蛋白的功能进行分析, 推测杀雄剂SQ-1诱导小麦雄性不育可能与能量代谢失衡、淀粉合成受抑制、活性氧积累、细胞凋亡以及花器官发育调节基因作用失控等有关.  相似文献   
928.
In this study, the factors affecting ferulic acid (FA) release from Brewer’s spent grain (BSG), by the crude enzyme extract of Fusarium oxysporum were investigated. In order to evaluate the importance of the multienzyme preparation on FA release, the synergistic action of feruloyl esterase (FAE, FoFaeC-12213) and xylanase (Trichoderma longibrachiatum M3) monoenzymes was studied. More than double amount of FA release (1 mg g−1 dry BSG) was observed during hydrolytic reactions by the crude enzyme extract compared to hydrolysis by the monoenzymes (0.37 mg g−1 dry BSG). The protease content of the crude extract and the inhibitory effect of FA as an end-product were also evaluated concerning their effect on FA release. The protease treatment prior to hydrolysis by monoenzymes enhanced FA release about 100%, while, for the first time in literature, FA in solution found to have a significant inhibitory effect on FAE activity and on total FA release.  相似文献   
929.
Non destructive and mathematical approaches of modeling can be very convenient and useful for plant growth estimation. The leaf of Elaeagnus mollis was taken as the object of research. Leaf length、 leaf width、SPAD value and different combinations of these variables were developed models to predict individual leaf area, saturated fresh weight, and dry weight of Elaeagnus mollis. Ten regression equations were compared. Select fitting the best model as a predictive model in leaf area, saturated fresh weight and dry weight. The three models were as follows: individual leaf area LA=3647+0383LW+0001LWS (R=0968), saturated fresh weight SFW=-0464+0081L+000008LWS (R=0963), and dry weight DW=-0094+0032W+00001LS (R=0960). The best prediction model of LA, SFW and DW was validated with the measured value. The results showed that the predicted values and measured values were highly consistent. It could be used to predict the LA, SFW and DW of actual unknown leaves.  相似文献   
930.
Objective: Prospective studies have suggested that substituting whole grain for refined grain products may lower the risk of overweight and obesity. Breakfast cereal intake is a major source of whole and refined grains and has also been associated with having a lower BMI. The aim of this study was to prospectively assess the association between whole and refined grain breakfast cereal intakes and risk of overweight (BMI ≥ 25 kg/m2) and weight gain. Research Methods and Procedures: We examined 17, 881 U.S. male physicians 40 to 84 years of age in 1982 who were free of cardiovascular disease, diabetes mellitus, and cancer at baseline and reported measures of breakfast cereal intake, weight, and height. Results: Over 8 and 13 years of follow‐up, respectively, men who consumed breakfast cereal, regardless of type, consistently weighed less than those who consumed breakfast cereals less often (p value for trend = 0.01). Whole and refined grain breakfast cereal intake was inversely associated with body weight gain over 8 years, after adjustment for age, smoking, baseline BMI, alcohol intake, physical activity, hypertension, high cholesterol, and use of multivitamins. Compared with men who rarely or never consumed breakfast cereals, those who consumed ≥1 serving/d of breakfast cereals were 22% and 12% less likely to become overweight during follow‐up periods of 8 and 13 years (relative risk, 0.78 and 0.88; 95% confidence interval, 0.67 to 0.91 and 0.76 to 1.00, respectively). Discussion: BMI and weight gain were inversely associated with intake of breakfast cereals, independently of other risk factors.  相似文献   
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