全文获取类型
收费全文 | 688篇 |
免费 | 35篇 |
国内免费 | 56篇 |
出版年
2024年 | 3篇 |
2023年 | 6篇 |
2022年 | 30篇 |
2021年 | 28篇 |
2020年 | 23篇 |
2019年 | 31篇 |
2018年 | 17篇 |
2017年 | 21篇 |
2016年 | 14篇 |
2015年 | 23篇 |
2014年 | 37篇 |
2013年 | 83篇 |
2012年 | 36篇 |
2011年 | 39篇 |
2010年 | 24篇 |
2009年 | 35篇 |
2008年 | 33篇 |
2007年 | 36篇 |
2006年 | 33篇 |
2005年 | 30篇 |
2004年 | 27篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 10篇 |
2000年 | 12篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 12篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有779条查询结果,搜索用时 31 毫秒
81.
82.
地木耳提取物水溶液对花卉营养生长及开花的影响 总被引:2,自引:1,他引:1
在温室条件下,用1%的地木耳提取物水溶液对瓜叶菊(Seneciocruentus)、万寿菊(Tageteserecta)、矮牵牛(Petuniahybrida)、香石竹(Dianthuscaryophyllus)、一品红(Euphorbiapulcherrima)、仙客来(Cyclamenpersium)、一串红(Salviasplendens)等7种花坛花进行叶面喷施后,结果表明,7种花的株高、冠径、株鲜重、叶片数目、叶长、根长比对照均有显著增加(P<0.05);万寿菊,矮牵牛,一品红,一串红的平均株干重有显著增加,而瓜叶菊,香石竹,仙客来的平均株干重增加不显著(P>0.05);除了香石竹的叶宽有显著增加外,其余6种花的叶宽对1%地木耳提取物水溶液的反应不敏感;而7种花卉的叶厚都没有显著的变化。提取物水溶液还可促进花提早开花,增加花数目,并延长花期。 相似文献
83.
大孔吸附树脂对紫锥菊提取物中菊苣酸分离纯化的研究 总被引:7,自引:2,他引:5
采用大孔吸附树脂分离纯化紫锥菊提取物中免疫活性成分菊苣酸,7%(v/v)的甲醇-水溶液洗脱,HPLC法对产品中菊苣酸含量进行检测分析。该法能把紫锥菊提取物中菊苣酸含量(4%)提高9倍左右,回收率达到95%以上,且操作简单,可用于菊苣酸的分离纯化。 相似文献
84.
中草药提取物中缩合类单宁的选择性脱除 总被引:1,自引:0,他引:1
以皮胶原纤维为原料,通过甲醛交联反应制备吸附材料。采用外加单宁的方法研究了这种吸附材料对中草药提取物中缩合类单宁的选择性吸附能力。结果表明,胶原纤维吸附材料对落叶松单宁、黑荆树单宁和杨梅单宁等3种典型的缩合类单宁都具有非常好的吸附选择性,在实验条件下单宁的去除率达到100%,而对有效成份的吸附率较低。该吸附材料对与缩合类单宁具有相似结构的低聚原花青素的吸附率也较低。对比试验表明,胶原纤维吸附材料对单宁的吸附选择性优于聚酰胺。 相似文献
85.
86.
The cell-free extracts from animal Xenopus laevis egg could induce chromatin decon-densation and pronuclear formation from demembranated plant (Orychophragmus violaceus) sperm. The demembranated Orychophragmus violaceus sperm began to swell in 30 min incubation, and then were gradually decondensed. The reassembly of nuclear envelope in the reconstituted nuclei had been visualized by means of electron microscopy and fluorescent microscopy. Membrane vesicles fused to form the double envelope around the periphery of the decondensed chromatin. The morphology of the newly formed nucleus, with a double membrane, was similar to those nuclei after fertilization. Transmission electron microscope micrograph of the whole mount prepared nuclear matrix-lamina showed the reconstituted nucleus to be filled with a dense network. 相似文献
87.
88.
土茯苓提取物抗细菌活性的研究 总被引:4,自引:0,他引:4
通过测定土茯苓提取物对革兰氏阳性菌和革兰氏阴性菌的抑菌活性,来更全面的评价和综合利用土茯苓资源,实验结果表明土苓955乙醇和乙酸乙酯的提取物抑菌范围广,服抑菌活性强,这两种提取物的MIC和MBC值显示了土茯苓作为抗细菌资源的可利用价值。 相似文献
89.
A. Lagarto Parra R. Silva Yhebra I. Guerra Sardias L. Iglesias Buela 《Phytomedicine》2001,8(5):395-400
Artemia salina L. (Artemiidae), the brine shrimp larva, is an invertebrate used in the alternative test to determine toxicity of chemical and natural products. In this study the Medium Lethal Concentrations (LC50 value) of 20 plant extracts, Aloe vera (L.) Burm. F. (Aloeaceae), Artemisia absinthium L. (Asteraceae); Citrus aurantium L. (Rutaceae); Cymbopogon citratus (DC. Ex Nees) Stapf (Poaceae); Datura stramonium L. (Solanaceae); Justicia pectoralis Jacq. (Acanthaceae); Musa x paradisiaca L. (Musaceae); Ocimum basilicum L.; O. gratissimum L.; O. tenuiflorum L. (Lamiaceae); Pimenta dioica (L.) Merr. (Myrtaceae); Piper auritum Kunth (Piperaceae); Plantago major L. (Plantaginaceae); Plectranthus amboinicus (Lour.) Spreng. (Lamiaceae); Ruta graveolens L. (Rutaceae); Senna alata (L.) Roxb. (Fabaceae); Stachytarpheta jamaicensis (L.) Vahl (Verbenaceae); and Thuja occidentalis L. (Cupressaceae), were determined using Artemia salina L. (Artemiidae), with the objective of relating the results to the LD50 values reported in mice (tested at three concentrations: 10, 100, and 1000 microg/mL, for each extract). We found good correlation between the in vivo and the in vitro tests (r = 0.85 p < 0.05), and this method is a useful tool for predicting oral acute toxicity in plant extracts. 相似文献
90.
《Saudi Journal of Biological Sciences》2022,29(6):103287
Triphala is a famous triherbal drug, comprising three herb fruits, including Terminalia chebula (Haritaki), Terminalia bellirica (Bibhitaki), and Phyllanthus emblica (Amalaki). It is enriched with vitamin C, polyphenols, flavonoids, sterols, saponins, etc., and is well-documented for its potent antioxidant, anticancer, chemoprotective, antimicrobial, and anti-inflammatory effects. This research was conducted to evaluate the synergistic antioxidative and cytotoxic potential of mixtures of the individual constituents of Triphala at their nonequivalent ratios along with the chemical characterization of individual constituents of Triphala to identify and quantify individual compounds. The antioxidative potential was measured using total antioxidant capacity (TAC), DPPH free radical scavenging assay, and total phenolic content (TPC) tests. The cytotoxic potential was assessed on brain cancer cells (N4X4) using MTT assay, and phytochemical characterization was performed by GS-MS analysis. Nonequivalent ratios of Triphala constituents exhibited significantly higher synergistic antioxidant and cytotoxic potential than the equivalent ratios of them. Moreover, the nonequivalent ratio where the quantity of Amalaki was doubled than the other two constituents showed the highest synergistic antioxidant and cytotoxic effect. GC-MS analysis of individual constituents of Triphala identified and quantified the presence of a wide array of compounds, and fatty acid, fatty acid ester, triterpene, and aminoglycoside remained the predominant class of compounds. Thus, it can be inferred that the observed bioactivities can be attributed to the phytocompounds characterized and extracts at the nonequivalent ratio of Triphala constituents where Amalaki is doubled can be more effective in treating oxidative degenerative diseases and glioblastoma. 相似文献