全文获取类型
收费全文 | 1556篇 |
免费 | 134篇 |
国内免费 | 169篇 |
出版年
2024年 | 11篇 |
2023年 | 20篇 |
2022年 | 53篇 |
2021年 | 85篇 |
2020年 | 42篇 |
2019年 | 43篇 |
2018年 | 61篇 |
2017年 | 46篇 |
2016年 | 59篇 |
2015年 | 74篇 |
2014年 | 83篇 |
2013年 | 105篇 |
2012年 | 139篇 |
2011年 | 147篇 |
2010年 | 70篇 |
2009年 | 69篇 |
2008年 | 112篇 |
2007年 | 75篇 |
2006年 | 71篇 |
2005年 | 50篇 |
2004年 | 45篇 |
2003年 | 47篇 |
2002年 | 39篇 |
2001年 | 44篇 |
2000年 | 37篇 |
1999年 | 21篇 |
1998年 | 14篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 22篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 18篇 |
1988年 | 12篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1971年 | 5篇 |
排序方式: 共有1859条查询结果,搜索用时 46 毫秒
21.
Oral administration of spirobishexahydropyrimidine showed an increase in the activity of serum transaminases, lactate dehydrogenase and alkaline phosphatase. Biological half life and other pharmacokinetic parameters showed rapid absorption and slow elimination of the drug. 相似文献
22.
23.
24.
Expression of reg/PSP, a pancreatic exocrine gene: relationship to changes in islet beta-cell mass 总被引:5,自引:0,他引:5
C Miyaura L Chen M Appel T Alam L Inman S D Hughes J L Milburn R H Unger C B Newgard 《Molecular endocrinology (Baltimore, Md.)》1991,5(2):226-234
A cDNA termed reg was recently isolated by differential screening of a library prepared from regenerating islets isolated from pancreatic remnants of rats subjected to 90% pancreatectomy and nicotinamide treatment. This led to speculation that this gene may be involved in expansion of beta-cell mass. In the current study we have measured reg expression after implantation and resection of a solid insulinoma tumor into rats, maneuvers known, respectively, to reduce and reexpand the volume of beta-cells in the islet. Animals with an implanted insulinoma tumor became profoundly hypoglycemic. Islet beta-cells declined from the normal 75% of total islet volume to less than 30%, in concert with a marked reduction in the reg mRNA level. Removal of the tumor resulted in a sharp increase in beta-cell replication, as measured by [3H]thymidine incorporation and a return to normal beta-cell volume within 4 days of tumor resection. This was associated with a transient induction in reg expression compared to that in tumor-bearing animals, effectively returning the amount of reg mRNA to the levels found in normal animals within 48 h; at later time points after tumor removal (3-7 days) reg expression declined, but then rose toward normal. In situ hybridization analysis localized the initial induction in reg mRNA expression to the exocrine pancreas. Continuous infusion of insulin into normal rats for 4 days, a maneuver that does not significantly reduce beta-cell mass, resulted in dramatically reduced insulin mRNA in islets, but no change in the levels of reg mRNA. We conclude that the diminution in pancreatic beta-cell mass caused by subcutaneous implantation of an insulinoma is associated with reduced reg gene expression and that the increase in beta-cell replication after resection of the tumor is preceded by return of reg gene expression toward normal. 相似文献
25.
M Alam M Ahmad A Rasheed M Saleem M K Javaid S Ikram 《Indian journal of experimental biology》1990,28(10):940-942
The metabolic fate of isatin hydrazone (Ia), isatin-3-thiosemicarbazone (Ib), isatin-3-semicarbazone (Ic), isatin-3-phenylhydrazone (Id), isatin oxime (Ie) and 3-hydroxy-3-acetonyl oxindole (II) was studied in rabbits. The compounds were administered orally in the dose of 300 mg/kg body wt. Isatin anthranilic acid, tryptophan and nicotinic acid were identified as the major metabolites excreted in urine. The 3-hydroxy-3-acetonyl oxindole (II) gave on additional metabolite, oxindole. The major metabolites were separated and identified unambiguously on thin layer silica gel plate. Metabolic pathways have been proposed to explain the biotransformation of the compounds investigated. 相似文献
26.
Reporter genes: application to the study of mammalian gene transcription 总被引:32,自引:0,他引:32
27.
The dinoflagellate was investigated for its sterol composition. Five of the six sterols were isolated and identified as cholest-5-en-3β-ol, (24ξ)-24-methylcholest-5-en-3β-ol, stigmasta-5,22-dien-3β-ol, (22E,24R)-4α,23,24-trimethyl-5α-cholest-22-en-3β-ol, and 4α,23ξ,24ξ-trimethyl-5α-cholestan-3β-ol. 相似文献
28.
栓孔菌属漆酶高产菌株的初步筛选及其产酶条件的优化 总被引:4,自引:1,他引:3
利用显色反应对栓孔菌属(Trametes)进行了漆酶高产菌株的筛选,并对目标菌株的产酶条件进行了优化,在添加愈创木酚的固体培养基中,通过显色反应初步筛选出漆酶高产菌株东方栓孔菌Trametes orientalis Cui 6300;进一步通过单因子分析、正交试验和ABTS法确定了菌株Cui 6300的最适产酶条件:麦芽糖15 g/L,蛋白胨3 g/L,pH 4.8,Cu2+2.0 mmol/L,培养温度28°C,接种饼直径1.5 cm,此时酶活最高可达19.923 U/mL;同时探索了Cu2+浓度及添加时间对其菌丝生物量和漆酶活力的影响。研究表明,Cu2+最适添加浓度为2.0 mmol/L,添加时间为接种后第3天。 相似文献
29.
30.
为建立龙珠果(Passiflora foetida)的快繁再生体系,以实生苗茎段为外植体,研究了植物生长调节剂对丛生芽诱导、壮苗生根的影响,同时对组培苗的耐盐性进行研究.结果表明,MS+6-BA 0.5 mg/L+NAA 0.05 mg/L培养基有利于诱导丛生芽并促进芽的生长;MS+6-BA 3.0 mg/L+NAA ... 相似文献