全文获取类型
收费全文 | 897篇 |
免费 | 69篇 |
国内免费 | 63篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 47篇 |
妇产科学 | 2篇 |
基础医学 | 103篇 |
口腔科学 | 24篇 |
临床医学 | 92篇 |
内科学 | 172篇 |
皮肤病学 | 24篇 |
神经病学 | 17篇 |
特种医学 | 257篇 |
外科学 | 38篇 |
综合类 | 57篇 |
预防医学 | 33篇 |
眼科学 | 5篇 |
药学 | 134篇 |
肿瘤学 | 22篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 12篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 11篇 |
2014年 | 16篇 |
2013年 | 16篇 |
2012年 | 4篇 |
2011年 | 9篇 |
2010年 | 20篇 |
2009年 | 27篇 |
2008年 | 10篇 |
2007年 | 39篇 |
2006年 | 19篇 |
2005年 | 27篇 |
2004年 | 13篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 26篇 |
2000年 | 13篇 |
1999年 | 27篇 |
1998年 | 57篇 |
1997年 | 63篇 |
1996年 | 57篇 |
1995年 | 57篇 |
1994年 | 34篇 |
1993年 | 42篇 |
1992年 | 15篇 |
1991年 | 19篇 |
1990年 | 25篇 |
1989年 | 49篇 |
1988年 | 35篇 |
1987年 | 39篇 |
1986年 | 25篇 |
1985年 | 28篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 18篇 |
1981年 | 20篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1975年 | 9篇 |
排序方式: 共有1029条查询结果,搜索用时 15 毫秒
21.
22.
23.
The prevalence of microalbuminuria was assessed in 50 patients of non-insulin dependent diabetes mellitus. The mean age of patients was 52.1 ± 11.6 years and the duration of diabetes was 8.3 ± 6.8 years. Twenty (40%) patients had microalbuminuria. Microalbuminuria was more common in patients with a longer duration of diabetes (more than 5 years), a poor glycaemic control, and higher systolic blood pressure.KEY WORDS: Microalbuminuria, Diabetes mellitus, Diabetic nephropathy, Chronic renal failure 相似文献
24.
A nationwide study of intracellular drug metabolite concentrations in children prescribed 6-mercaptopurine for the treatment of lymphoblastic leukaemia was carried out to assess interpatient variability at a standardised dose. Nine children (2% of the total) had completely undetectable metabolites, indicative of non-compliance. Five were adolescents, but otherwise they had no obvious distinguishing characteristics. Not taking any 6-mercaptopurine at all is uncommon, but the problem cannot be predicted. The total number of children who do not comply cannot be determined from this study, but the nine children described represent only a fraction of these. 相似文献
25.
Zhao P Cao J Zhao LJ Qin ZL Ke JS Pan W Ren H Yu JG Qi ZT 《第二军医大学学报》2006,27(5):506-506
The nucleocapsid (N) protein of SARS-coronavirus (SARS-CoV) is the key protein for the formation of the helical nucleocapsid during virion assembly. This protein is believed to be more conserved than other proteins of the virus, such as spike and membrane glycoprotein. In this study, the N protein of SARS-CoV was expressed in Escherichia coli DHSalpha and identified with pooled sera from patients in the convalescence phase of SARS. A plasmid pCI-N, encoding the full-length N gene of SARS-CoV, was constructed. Expression of the N protein was observed in COS1 cells following transfection with pCI-N. The immune responses induced by intramuscular immunization with pCI-N were evaluated in a murine model. Serum anti-N immunoglobutins and splenocytes proliferative responses against N protein were observed in immunized BALB/c mice. The major immunoglobulin G subclass recognizing N protein was immunoglobulin G2a, and stimulated splenocytes secreted high levels of gamma interferon and IL-2 in response to N protein. More importantly, the immunized mice produced strong delayed-type hypersensitivity (DTH) and CD^8+ CTL responses to N protein. 相似文献
26.
Diffusion-Weighted Magnetic Resonance Imaging as a Cancer Biomarker: Consensus and Recommendations 总被引:3,自引:0,他引:3 下载免费PDF全文
Anwar R Padhani Guoying Liu Dow Mu-Koh Thomas L Chenevert Harriet C Thoeny Taro Takahara Andrew Dzik-Jurasz Brian D Ross Marc Van Cauteren David Collins Dima A Hammoud Gordon JS Rustin Bachir Taouli Peter L Choyke 《Neoplasia (New York, N.Y.)》2009,11(2):102-125
On May 3, 2008, a National Cancer Institute (NCI)-sponsored open consensus conference was held in Toronto, Ontario, Canada, during the 2008 International Society for Magnetic Resonance in Medicine Meeting. Approximately 100 experts and stakeholders summarized the current understanding of diffusion-weighted magnetic resonance imaging (DW-MRI) and reached consensus on the use of DW-MRI as a cancer imaging biomarker. DW-MRI should be tested as an imaging biomarker in the context of well-defined clinical trials, by adding DW-MRI to existing NCI-sponsored trials, particularly those with tissue sampling or survival indicators. Where possible, DW-MRI measurements should be compared with histologic indices including cellularity and tissue response. There is a need for tissue equivalent diffusivity phantoms; meanwhile, simple fluid-filled phantoms should be used. Monoexponential assessments of apparent diffusion coefficient values should use two b values (> 100 and between 500 and 1000 mm2/sec depending on the application). Free breathing with multiple acquisitions is superior to complex gating techniques. Baseline patient reproducibility studies should be part of study designs. Both region of interest and histogram analysis of apparent diffusion coefficient measurements should be obtained. Standards for measurement, analysis, and display are needed. Annotated data from validation studies (along with outcome measures) should be made publicly available. Magnetic resonance imaging vendors should be engaged in this process. The NCI should establish a task force of experts (physicists, radiologists, and oncologists) to plan, organize technical aspects, and conduct pilot trials. The American College of Radiology Imaging Network infrastructure may be suitable for these purposes. There is an extraordinary opportunity for DW-MRI to evolve into a clinically valuable imaging tool, potentially important for drug development. 相似文献
27.
Further comparison of contractions of the smooth muscle of the guinea-pig isolated vas deferens induced by ATP and related analogs 总被引:8,自引:0,他引:8
Some structural requirements which are important for the contractile activity of adenine nucleotides at P2-purinergic receptors in the guinea-pig isolated vas deferens were examined. The consequences of deletions, substitutions and isosteric rearrangements in 1-N, C-2, C-8, N-9 and N6 of adenine, in the ribose hydroxyls, and in the polyphosphate chain were examined. Several kinds of effects on activity were observed, including potentiation of responses, losses in activity, modifications of response duration, and transitions from biphasic concentration-response curves, which are characteristic of ATP, to monophasic curves. Generally, deletions and substitutions to adenine reduced activity. Ribose modifications were better-tolerated. The presence of 5'-phosphate or phosphorothioate moieties was required for maximum activity. A comparison of the present results with previous reports indicates that certain modifications to ATP result in similar effects in both the vas deferens and urinary bladder, which are opposite those which occur in the taenia coli. 相似文献
28.
千层塔中三萜成分的研究 总被引:5,自引:0,他引:5
前曾报道自千层塔[Huperzia serrata Thunb.(Trev)=Lycopodium serratum Thunb(Trev.)]中分得具有胆碱酯酶抑制活性的新生物碱——石杉碱甲、石杉碱乙、甲基石杉碱乙及已知生物碱8-deoxyserratinine,serratinine,lycodoline及lycoclavine。为进一步阐明该植物的化学成分,我们对其三萜成分进行了研究。从浙江安吉产的千层塔植物中分到六个石松三萜,其中一个为新化合物,经下述方法推定为serratenediol-21-acetate(Ⅰ)。另五 相似文献
29.
本文报道我国西南产麻黄——丽江麻黄Ephedra likiangensis Florin、匍枝丽江麻黄E.likiangensis f.mairei(Florin)C.Y.Cheng、藏麻黄E.saxatilis Royle ex Florin、山岭麻黄E.gerardiana Wall、垫状山岭麻黄E.gerardiana Var.congesta C.Y.Cheng、矮麻黄E.minuta Florin和异株矮麻黄E.minuta var.dioeca C.Y.Cheng,以及形态组织特征较特殊的宁夏产斑子麻黄E.lepidosperma C.Y.Cheng、新疆产窄膜麻黄E.lomatolepis Schrenk,西藏产西藏中麻黄E.intermedia var.tibetica Stapf的生药形态组织学研究结果。并根据对国产麻黄的生药形态组织学的系统研究结果,分别编写了各种国产麻黄(包括13种3变种1变型)的生药性状和生药显微特征检索表。 相似文献
30.