全文获取类型
收费全文 | 790篇 |
免费 | 71篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 37篇 |
妇产科学 | 8篇 |
基础医学 | 86篇 |
口腔科学 | 13篇 |
临床医学 | 87篇 |
内科学 | 158篇 |
皮肤病学 | 56篇 |
神经病学 | 52篇 |
特种医学 | 49篇 |
外科学 | 61篇 |
综合类 | 26篇 |
预防医学 | 91篇 |
眼科学 | 6篇 |
药学 | 86篇 |
中国医学 | 1篇 |
肿瘤学 | 40篇 |
出版年
2021年 | 12篇 |
2020年 | 18篇 |
2019年 | 11篇 |
2018年 | 17篇 |
2017年 | 9篇 |
2016年 | 15篇 |
2015年 | 18篇 |
2014年 | 22篇 |
2013年 | 17篇 |
2012年 | 35篇 |
2011年 | 42篇 |
2010年 | 30篇 |
2009年 | 18篇 |
2008年 | 30篇 |
2007年 | 23篇 |
2006年 | 39篇 |
2005年 | 34篇 |
2004年 | 31篇 |
2003年 | 28篇 |
2002年 | 23篇 |
2001年 | 25篇 |
2000年 | 16篇 |
1999年 | 18篇 |
1998年 | 24篇 |
1997年 | 14篇 |
1996年 | 20篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 16篇 |
1992年 | 18篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 23篇 |
1988年 | 16篇 |
1987年 | 22篇 |
1986年 | 18篇 |
1985年 | 10篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1969年 | 4篇 |
1965年 | 3篇 |
排序方式: 共有868条查询结果,搜索用时 171 毫秒
81.
Mangesh C Deshpande Martin C Garnett M Vamvakaki Lindsey Bailey Steven P Armes Snjezana Stolnik 《Journal of controlled release》2002,81(1-2):185-199
The influence of polymer structure on the characteristics of complexes of a phosphorothioate antisense oligonucleotide (ISIS 5132) was studied, using well-defined cationic copolymers based on 2-(dimethylamino) ethyl methacrylate (DMAEMA) and poly(ethylene glycol) (PEG). The three related copolymer structures were: DMAEMA-PEG (a diblock copolymer) DMAEMA-OEGMA 7 (a brush-type copolymer), DMAEMA-stat-PEGMA (a comb-type copolymer); each of these were examined together with DMAEMA homopolymer, which served as a control. The results revealed that all the polymers exhibited good binding ability with the oligonucleotide (ON). Interestingly, the comb-type polymer DMAEMA-stat-PEGMA demonstrated the highest binding ability and DMAEMA homopolymer the lowest, as judged by a dye displacement assay. DMAEMA homopolymer produced large agglomerates of smaller individual complexes as observed by optical density, photon correlation spectroscopy and transmission electron microscopy studies. In contrast, two PEG-block copolymers, DMAEMA-PEG and DMAEMA-OEGMA 7, formed compact complexes of 80-150 nm which had good long-term colloidal stability. This is attributed to the steric stabilisation effect of the PEG chains on the ON-copolymer complexes. These two copolymers are believed to form complexes with ON that have a micellar structure. Comb-type DMAEMA-stat-PEGMA copolymer formed highly soluble complexes with the ON that did not phase separate from the buffer solution. This study clearly demonstrates that varying the copolymer architecture allows access to a range of ON complexes. In vitro cytotoxicity experiments on HepG2 cells showed that all of the tertiary amine methacrylate copolymers displayed lower cytotoxicity than the control poly(L-lysine). 相似文献
82.
83.
84.
85.
G C Cupit W R Garnett J R Powell J A Romankiewicz 《The American journal of nursing》1972,72(12):2210-2212
86.
Ide Cremin Constance Nyamukapa Lorraine Sherr Timothy B. Hallett Godwin Chawira Simon Cauchemez Ben Lopman Geoffrey P. Garnett Simon Gregson 《AIDS and behavior》2010,14(3):708-715
Voluntary counselling and testing (VCT) is promoted as a potential HIV prevention measure. We describe trends in uptake of
VCT for HIV, and patterns of subsequent behaviour change associated with receiving VCT in a population-based open cohort in
Manicaland, Zimbabwe. The relationship between receipt of VCT and subsequent reported behaviour was analysed using generalized
linear models with random effects. At the third survey, 8.6% of participants (1,079/12,533), had previously received VCT.
Women who received VCT, both those positive and negative, reduced their reported number of new partners. Among those testing
positive, this risk reduction was enhanced with time since testing. Among men, no behavioural risk reduction associated with
VCT was observed. Significant increases in consistent condom use, with regular or non-regular partners, following VCT, were
not observed. This study suggests that, among women, particularly those who are infected, behavioural risk reduction does
occur following VCT. 相似文献
87.
The objective of this study was to evaluate the effectiveness of interventions aimed at improving clinical insulin resistance and/or pre‐diabetes in children. This study is a systematic review and meta‐analysis. Five electronic databases were searched for randomized controlled trials of at least 2‐months' duration. The outcomes were fasting insulin, homeostasis model assessment of insulin resistance (HOMA‐IR), body mass index (BMI) and adverse outcomes. Four randomized controlled trials were identified. All compared the effect of 6 months of metformin plus or minus lifestyle intervention with placebo plus or minus lifestyle intervention. After pooling results from three trials, the mean difference after 6 months favoured the intervention with a statistically significant mean decrease in fasting insulin, HOMA‐IR and BMI of 9.6 µU mL−1 (95% confidence interval [CI]: 6.3, 13.0 µU mL−1; I2 = 76%), 2.7 (95% CI: 1.7, 3.6; I2 = 74%) and 1.7 kg m−2 (95% CI: 1.1, 2.3 kg m−2; I2 = 75) respectively. Mild gastrointestinal symptoms were reported in 19% (2–29%; median and range) of participants taking metformin. Metformin improves markers of insulin sensitivity and reduces BMI in children and adolescents with clinical insulin resistance or pre‐diabetes. Stronger evidence from high‐quality studies of longer duration and larger sample size are required before clinical conclusions about the optimal treatment protocol in this population can be drawn. 相似文献
88.
89.
Vllasaliu D Casettari L Fowler R Exposito-Harris R Garnett M Illum L Stolnik S 《International journal of pharmaceutics》2012,430(1-2):151-160
This work explored the interaction of chitosan with Calu-3 and Caco-2 cell lines, as models of the airway and intestinal epithelium, respectively. The toxicity, tight junction opening and mucoadhesive effects of chitosan were compared in the two cell lines. Additionally, the role of mucus in the absorption-promoting activity of chitosan was studied systematically. Notably, chitosan exhibited a different degree of toxicity on the Calu-3 and Caco-2 cells. Chitosan's tight junction-opening effect, observed in terms of reduction of transepithelial electrical resistance and permeability enhancement, was apparent in both cell lines, though somewhat lower in Caco-2 compared to Calu-3 cell layers (though overall permeability was higher in the former). Tight junction opening and association of chitosan with the epithelial cell layers were more prominent in mucus-containing than in mucus-depleted Calu-3 cells and non mucus-excreting Caco-2 monolayers. Overall, the work suggests that chitosan exhibits a different level of toxicity in airway, as compared to intestinal cells and although absorption enhancement is apparent in both cell lines, enabling its potential use as an absorption-promoting excipient in both pulmonary and oral macromolecular delivery, the magnitude and the duration of the effect are dependent on the level of mucus present on the epithelial surfaces. 相似文献
90.
Expression of activation-induced cytidine deaminase (AID) by germinal center (GC) B cells drives the processes of immunoglobulin (Ig) somatic hypermutation (SHM) and class switch recombination (CSR) necessary for the generation of high affinity IgG serum antibody and the memory B-cell compartment. Increasing evidence indicates that AID is also expressed at low levels in developing B cells but to date, this early, developmentally regulated AID expression has no known function. Does the timing and extent of AID expression in developmentally immature, non-GC B cells provide clues to reveal its physiologic role? 相似文献