收费全文 | 38144篇 |
免费 | 1809篇 |
国内免费 | 304篇 |
耳鼻咽喉 | 343篇 |
儿科学 | 694篇 |
妇产科学 | 436篇 |
基础医学 | 5033篇 |
口腔科学 | 1019篇 |
临床医学 | 2409篇 |
内科学 | 9433篇 |
皮肤病学 | 867篇 |
神经病学 | 2578篇 |
特种医学 | 1313篇 |
外科学 | 6848篇 |
综合类 | 170篇 |
一般理论 | 1篇 |
预防医学 | 1035篇 |
眼科学 | 664篇 |
药学 | 2292篇 |
中国医学 | 137篇 |
肿瘤学 | 4985篇 |
2023年 | 210篇 |
2022年 | 552篇 |
2021年 | 912篇 |
2020年 | 464篇 |
2019年 | 670篇 |
2018年 | 876篇 |
2017年 | 678篇 |
2016年 | 789篇 |
2015年 | 832篇 |
2014年 | 1118篇 |
2013年 | 1413篇 |
2012年 | 2310篇 |
2011年 | 2689篇 |
2010年 | 1527篇 |
2009年 | 1260篇 |
2008年 | 2312篇 |
2007年 | 2531篇 |
2006年 | 2376篇 |
2005年 | 2543篇 |
2004年 | 2463篇 |
2003年 | 2451篇 |
2002年 | 2487篇 |
2001年 | 463篇 |
2000年 | 384篇 |
1999年 | 511篇 |
1998年 | 600篇 |
1997年 | 477篇 |
1996年 | 446篇 |
1995年 | 387篇 |
1994年 | 336篇 |
1993年 | 306篇 |
1992年 | 260篇 |
1991年 | 243篇 |
1990年 | 232篇 |
1989年 | 245篇 |
1988年 | 193篇 |
1987年 | 165篇 |
1986年 | 176篇 |
1985年 | 180篇 |
1984年 | 144篇 |
1983年 | 128篇 |
1982年 | 90篇 |
1981年 | 104篇 |
1980年 | 92篇 |
1979年 | 100篇 |
1978年 | 68篇 |
1977年 | 48篇 |
1975年 | 48篇 |
1974年 | 42篇 |
1973年 | 44篇 |
The common marmoset (Callithrix jacchus) is a useful experimental animal to evaluate the pharmacokinetics of drug candidates. Cytochrome P450 (P450) 2B enzyme in marmoset livers has been identified; however, only limited information on the enzymatic properties and distribution has been available.
Marmoset P450 2B6 amino acids showed high sequence identities (>86%) with those of primates including humans and cynomolgus monkeys. Phylogenetic analysis using amino acid sequences indicated that marmoset P450 2B6 was closer to human and cynomolgus monkey P450 2B6 than to P450 2B orthologs of other species, including pigs, dogs, rabbits and rodents.
Quantitative polymerase chain reaction analysis using specific primers showed P450 2B6 mRNA predominantly expressed in livers among the five marmoset tissues, similar to those of humans and cynomolgus monkeys.
Marmoset P450 2B6 heterologously expressed in Escherichia coli membranes oxidized 7-ethoxycoumarin, pentoxyresorufin, propofol and testosterone, at roughly similar rates to those of humans and/or cynomolgus monkeys. A high capacity of marmoset P450 2B6 with propofol 4-hydroxylation (at low ionic strength conditions) with a low Km value was relatively comparable to that for marmoset livers.
These results collectively indicated a high propofol 4-hydroxylation activity of P450 2B6 expressed in marmoset livers.
Methods: Hybrid cells containing a fragment of human chromosome 8 in scid cells (RD13B2) were used. DNA-PK activity was measured by an in vitro assay. Immunoprecipitation of the nuclear extract was performed with an anti-Ku80 antibody. Proteins co-precipitated with Ku80 were separated by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis and detected by Western blotting using anti-heat shock protein (HSP)72 and anti-heat shock cognate protein (HSC)73 antibodies. HSC73 was overexpressed with the pcDNA3.1 vector. Short hairpin (sh)RNA was used to downregulate HSC73 and HSP72.
Results: The activity of heat-inactivated DNA-PK recovered to about 50% of control during an additional incubation at 37?°C after heat treatment at 44?°C for 15?min in the presence of cycloheximide (which inhibits de novo protein synthesis). Maximal recovery was observed within 3?h of incubation at 37?°C after heat treatment. Constitutively expressed HSC73, which folds newly synthesized proteins, reached maximal levels 3?h after heat treatment using a co-immunoprecipitation assay with the Ku80 protein. Inhibiting HSC73, but not HSP72, expression with shRNA decreased the recovery of DNA-PK activity after heat treatment.
Conclusions: These results suggest that de novo protein synthesis is unnecessary for recovery of some heat-inactivated DNA-PK. Rather, it might be reactivated by the molecular chaperone activity of HSC73, but not HSP72. 相似文献
Methods: Individuals who visited the outpatient clinic or were admitted to the palliative care unit were eligible. Patients with a performance status of 4 and/or those unable to complete questionnaires were excluded. PA was evaluated using a bioanalyzer device. The correlation coefficient between PA and the variables of interest was analyzed.
Results: A total of 102 patients were analyzed. PA was weakly correlated with age (ρ = ?0.22), performance status (ρ = ?0.30), functional well-being (ρ?=?0.20), anorexia/cachexia subscale (ρ?=?0.22), and Functional Assessment of Anorexia/Cachexia Therapy trial outcome index (ρ?=?0.26). PA was also correlated with fluid retention (ρ = ?0.34) and albumin (ρ?=?0.32), C-reactive protein (ρ = ?0.31), and hemoglobin (ρ?=?0.41) levels. Sub-analysis stratified according to sex revealed that males demonstrated the same results; however, female sex demonstrated a correlation between PA and social well-being (ρ = ?0.43).
Conclusions: PA was correlated with physical condition, but not with psychological well-being. 相似文献
![点击此处可从《Clinical endocrinology》网站下载免费的PDF全文](/ch/ext_images/free.gif)