全文获取类型
收费全文 | 1832篇 |
免费 | 106篇 |
国内免费 | 228篇 |
出版年
2023年 | 11篇 |
2022年 | 23篇 |
2021年 | 18篇 |
2020年 | 57篇 |
2019年 | 43篇 |
2018年 | 30篇 |
2017年 | 33篇 |
2016年 | 55篇 |
2015年 | 75篇 |
2014年 | 88篇 |
2013年 | 155篇 |
2012年 | 80篇 |
2011年 | 61篇 |
2010年 | 85篇 |
2009年 | 77篇 |
2008年 | 81篇 |
2007年 | 74篇 |
2006年 | 74篇 |
2005年 | 58篇 |
2004年 | 47篇 |
2003年 | 57篇 |
2002年 | 60篇 |
2001年 | 43篇 |
2000年 | 53篇 |
1999年 | 76篇 |
1998年 | 82篇 |
1997年 | 68篇 |
1996年 | 45篇 |
1995年 | 41篇 |
1994年 | 46篇 |
1993年 | 36篇 |
1992年 | 45篇 |
1991年 | 43篇 |
1990年 | 36篇 |
1989年 | 26篇 |
1988年 | 28篇 |
1987年 | 20篇 |
1986年 | 16篇 |
1985年 | 14篇 |
1984年 | 29篇 |
1983年 | 12篇 |
1982年 | 16篇 |
1981年 | 12篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1975年 | 5篇 |
1973年 | 2篇 |
1972年 | 3篇 |
排序方式: 共有2166条查询结果,搜索用时 15 毫秒
91.
Smitha Renganathan Anand Srivastava Radhakrishna Gopala Pillai 《Biochemistry and Biophysics Reports》2020
BackgroundHyperglycemia and hyper oxidative stress are indicators of diabetes mellitus which is also accompanied with decreased levels of antioxidant enzymes. While oxidative stress is important in increasing insulin secretion and controlling blood sugar level at the same time excess oxidative stress leads to the destruction of beta cells of pancreas resulting in to low insulin production and hyperglycemia. A balance between the levels of oxidative radicals and insulin production is needed, but is not defined yet. Hyperglycemia also leads to hyperlipidemia which can contribute to various health conditions like cardiovascular diseases.ObjectivesThis study was designed to study the oxidative stress and lipid levels in diabetic rats. This also was designed to elucidate the effect of Dhanwantaram Kashayam, an Ayurvedic polyphenolic derived from plants on lipid metabolism and oxidative radical scavenging in diabetic rats.MethodsRats were made diabetic by injecting streptozotocin. Different enzymes involved in oxidative radical scavenging and lipid profiles including triglycerides, total cholesterol, free fatty acids and phospholipids were estimated using standard methods reported elsewhere.ResultsLevel of antioxidant enzymes were lower in diabetic rats compared to normal controls. Administration of Dhanwantaram Kashayam restored the enzyme activity as well as reduced levels of different lipids in diabetic rats.ConclusionsAdministration of Dhanwantaram Kashayam increased the activity levels of antioxidant enzymes and reduced the levels of total cholesterol, phospholipids and triglycerides. The results of this study point to the possibility of developing Dhanwantaram Kashayam as a dietary supplement which can alleviate the complications associated with diabetes or prevent them altogether. 相似文献
92.
93.
94.
The study was carried out in 31 workers co-exposed to cadmium, lead and zinc fumes and dusts in a zinc ore refinery. Urinary cadmium, lead, zinc, β2-M levels and NAG activities were determined to evaluate the possible dose-effect relationship between these parameters. A correlation was found between urinary cadmium, lead and zinc concentrations, and urinary β2-M levels and NAG activities of the exposed group. A statistically significant increase was also observed for urinary NAG activity in exposed workers who had urinary cadmium concentrations > 2 μg g?1 creatinine. However, in the same exposed group, the increment of β2-M was not statistically significant. In conclusion, the present study thus confirms the earlier observations and may suggest the notion that the urinary NAG seems to be a more sensitive indicator than urinary β2-M level in early stages of renal injury of moderately cadmium co-exposure with lead and zinc even at urinary cadmium concentration as low as 2 μg g?1 creatinine. When the earlier studies on the irreversibility of cadmium-induced tubular dysfunction and the present results were taken into consideration, the present health-based biological limit proposed by the WHO (5 μg g?1 creatinine) seems to be high for the occupational exposure to cadmium. 相似文献
95.
96.
97.
李月灵;金则新;管铭;左威 《植物研究》2013,33(6):684-689
为探讨铜(Cu)胁迫条件下土壤微生物对海州香薷(Elsholtzia splendens)光合生理和叶绿素荧光参数的影响,实验设置添加Cu(Cu胁迫)、接种土壤微生物、添加Cu与接种土壤微生物等3个处理,以不添加Cu与不接种土壤微生物为对照(CK)。结果表明:接种土壤微生物处理的植株相对叶绿素含量、净光合速率(Pn)、水分利用效率(WUE)均显著高于CK;且对初始荧光(Fo)和最大光化学效率(Fv/Fm)均有显著性影响。与CK相比,添加Cu降低了海州香薷的Pn和气孔导度(Gs),但胞间CO2浓度(Ci)的变化与Pn相反,表明其对光合作用的影响主要是非气孔限制因素。添加Cu的植株相对叶绿素含量显著下降,但Cu胁迫下接种土壤微生物提高了植株相对叶绿素含量,差异显著。在Cu胁迫条件下,接种土壤微生物的植株具有较高的Fv/Fm及较低的Fo,显著提高了海州香薷的WUE、Pn、Gs。说明接种土壤微生物可通过提高相对叶绿素含量、改善叶绿素荧光和光合作用来减轻Cu胁迫对海州香薷植株造成的伤害,从而提高海州香薷耐受Cu胁迫的能力。 相似文献
98.
99.
Dr. sc. Erich Kreuz Landw.-Techn. Assistent Kurt Engelhardt Staatl Gepr. Landwirt Erich Grazzeck 《Archives Of Phytopathology And Plant Protection》2013,46(4):359-364
Die herbizide Wirksamkeit von Bromoxynil und Phenmedipham wird in starkem Maße von der Lösungsmittelkomponente der Herbizidformulierung beeinflußt. Es zeigt sich, daß die Photosynthesehemmung — als Maß für die Herbizidwirkung — mit zunehmender Hydrophilie der verwendeten Lösungsmittel sinkt, was insbesondere anhand der untersuchten Essigsäurealkylesterreihe nachweisbar ist. Zwischen der Wirkstoffapplikation auf Ganzblättern und isolierten Chloroplasten treten beträchtliche Wirkungsunterschiede auf. Demnach ist der wirkungsbegrenzende Schritt nicht innerhalb der Thylakoidmembran selbst zu suchen sondern findet auf dem Wege von der Blattoberfläche zum Chloroplasten statt. 相似文献
100.
Rushda Sharf Hisamuddin Shiekh Abbasi Syed Ambreen Akhtar M.I. Robab 《Archives Of Phytopathology And Plant Protection》2013,46(5):622-630
An experiment was conducted to test the effect of different doses of 2, 4 and 8?g/2?kg of soil of Pochonia chlamydosporia against the root-knot nematode (Meloidogyne incognita) on Phaseolus vulgaris. It was observed that inoculation of plant with the nematode alone, and 15?days prior to fungal inoculation, reduced the plant growth when compared with the plant with fungal application followed by the nematode. Plant length, fresh and dry weight, chlorophyll, carotenoid, protein contents and nitrate reductase activity decreased in nematode-infested plants. Application of higher dose of 8?g/2?kg of soil of P. chlamydosporia increased all the plant growth parameters as well as biochemical parameters. Highest number of galls per root system was recorded on the plants infested with nematode but not treated with the fungus. However, application of fungus prior to nematode inoculation improved the plant growth and reduced the number of galls and the number of egg masses per root system. 相似文献