全文获取类型
收费全文 | 4002篇 |
免费 | 510篇 |
国内免费 | 1677篇 |
出版年
2024年 | 34篇 |
2023年 | 112篇 |
2022年 | 190篇 |
2021年 | 215篇 |
2020年 | 178篇 |
2019年 | 218篇 |
2018年 | 155篇 |
2017年 | 133篇 |
2016年 | 168篇 |
2015年 | 260篇 |
2014年 | 323篇 |
2013年 | 260篇 |
2012年 | 404篇 |
2011年 | 427篇 |
2010年 | 293篇 |
2009年 | 315篇 |
2008年 | 326篇 |
2007年 | 339篇 |
2006年 | 289篇 |
2005年 | 275篇 |
2004年 | 184篇 |
2003年 | 175篇 |
2002年 | 166篇 |
2001年 | 147篇 |
2000年 | 115篇 |
1999年 | 76篇 |
1998年 | 42篇 |
1997年 | 38篇 |
1996年 | 37篇 |
1995年 | 33篇 |
1994年 | 33篇 |
1993年 | 18篇 |
1992年 | 30篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 19篇 |
1987年 | 24篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 4篇 |
排序方式: 共有6189条查询结果,搜索用时 890 毫秒
121.
Y染色体上的短串联重复序列(Y chromosome short tandem repeats, Y-STRs)在法医鉴定,尤其是混合斑中男性成分的检测分析和家系排查中具有重要作用。随着Y-STR试剂盒的不断推出和数据库的建立,国内外针对不同地区和群体的Y-STR多态性研究日益增多,而有关铜川汉族Y-STR研究鲜有报道。基于此,采用YfilerTM Platinum复合扩增试剂盒对陕西铜川汉族669名无关男性个体进行38个Y-STR基因座遗传多态性调查,并探索铜川地区汉族与其他群体之间的遗传关系。调查共检出657种单倍型,单倍型多样性和识别能力分别为0.999 937 345和0.982 1。38个Y-STR基因座共检出428个等位基因,基因多样性值在0.108 9(DYS645)~0.969 9(DYS385)。群体遗传分析中,多维尺度分析(multi-dimensional scaling, MDS)和系统发育树分析结果显示铜川汉族与其他地区的汉族群体遗传距离更近。综上,研究结果中38个Y-STR基因座在铜川汉族群体中具有较高的遗传多态性,适合铜川地区法庭科学应用。 相似文献
122.
采用常规营养物质测定方法和气质联用(GC-MS)技术,研究了三疣梭子蟹软壳硬化阶段肝胰腺的基本营养成分和脂肪酸组成。结果发现在其软壳硬化的过程中肝胰腺指数、粗脂肪和灰分含量逐渐降低,而粗蛋白含量趋势相反;表明脂类是主要的能源物质。共检测出42种脂肪酸,其中C16:0(棕榈酸)、C18:1(n-9)(油酸)和C22:6(n-3)(DHA)是主要脂肪酸;蜕壳后0~6 h,单不饱和脂肪酸(MUFA)在肝胰腺中的含量显著降低(P<0.05),而饱和脂肪酸(SFA)和多不饱和脂肪酸(PUFA)的含量则均有不同程度的上升;6~48 h,MUFA在肝胰腺中的含量逐渐上升,PUFA的含量则与其相反;SFA在6~24 h时降低,随后升高;∑EPA+DHA在肝胰腺中的含量与∑PUFA的含量变化趋势一致。 相似文献
123.
Qingye Ou Jian’an He Chunqiao Liu Lei Shi Chunzhong Zhao Yungqing Xu Dayong Gu 《Biotechnology and Bioprocess Engineering》2013,18(5):1031-1037
The aim of this study was to construct a gene chip system based on a surface plasmon resonance technique, where peptide nucleic acid (PNA) oligomers are used as probes. Since the self-assembled monolayer (SAM) technology offers good control at the molecular level, we prepared 2D surface chemistry via SAM for probe attachments. PNA, which was designed according to the bioinformatics, was immobilized on the SAM-modified chip, and subsequently, relevant parameters of the experiment were ensured and optimized. Our results suggest that the ion strength and pH value of the buffer solution do not play significant roles in PNA or its complementary strand hybridization. The PNA probe binds to its complementary nucleic acid strand with a higher sensitivity and specificity compared to those of a traditional DNA probe. The PNA probe combined with surface plasmon resonance (SPR) technology has the benefits of being a label-free and in-real time monitor, as well as having improved hybridization and stability efficiency, which highlight the PNA gene chip detection system as a promising biosensor for clinical applications. 相似文献
124.
125.
Hongchi Yu Xianliang Huang Yunlong Ma Min Gao Ou Wang Ting Gao Yang Shen Xiaoheng Liu 《International journal of biological sciences》2013,9(9):966-979
Interleukin-8 (IL-8) is a common inflammatory factor, which involves in various non-specific pathological processes of inflammation. It has been found that increased endothelial permeability accompanied with high expression of IL-8 at site of injured endothelium and atherosclerotic plaque at early stages, suggesting that IL-8 participated in regulating endothelial permeability in the developing processes of vascular disease. The purpose of this study is to investigate the regulation effects of IL-8 on the vascular endothelial permeability, and the mRNA and protein expression of tight junction components (i.e., ZO-1, Claudin-5 and Occludin). Endothelial cells were stimulated by IL-8 with the dose of 50, 100 and 200 ng/mL, and duration of 2, 4, 6, 8h, respectively. The mRNA and protein expression level of tight junction components with IL-8 under different concentration and duration was examined by RT-PCR and Western blot, respectively. Meanwhile, the integrins induced focal adhesions event with IL-8 stimulation was also investigated. The results showed that IL-8 regulated the permeability of endothelium by down-regulation of tight junction in a dose- and time-dependence manner, but was not by integrins induced focal adhesions. This finding reveals the molecular mechanism in the increase of endothelial cell permeability induced by IL-8, which is expected to provide a new idea as a therapeutic target in vascular diseases. 相似文献
126.
Shengfu Chen Rongpei Wu Yanping Huang Fufu Zheng Yangbin Ou Xiangan Tu Yadong Zhang Yong Gao Xin Chen Tao Zheng Qiyun Yang Zi Wan Yuanyuan Zhang Xiangzhou Sun Guihua Liu Chunhua Deng 《PloS one》2013,8(12)
Background
Insulin resistance (IR) triggers endothelial dysfunction, which contributes to erectile dysfunction (ED) and cardiovascular disease.Aim
To evaluate whether IR was related to ED in young adult patients.Methods
A total of 283 consecutive men complaining of ED at least six months were enrolled, with a full medical history, physical examination, and laboratory tests collected. Quantitative Insulin Sensitivity Check Index (QUICKI) was used to determine IR. The severity of ED was assessed by IIEF-5 questionnaire. Endothelial function was assessed by ultrasonographic examination of brachial artery flow mediated dilation (FMD).Results
IR was detected in 52% patients. Subjects with IR had significant higher total cholesterol, triglycerides, low density lipoprotein-cholesterol (LDL-c), glycated haemoglobin (HBA1c), high sensitivity C-reactive protein (hs-CRP) and body mass index (BMI), but showed significant lower IIEF-5 score, FMD%, high density lipoprotein -cholesterol (HDL-c), testosterone, sex hormone binding globulin (SHBG) levels than patients without IR. Multiple regression analysis showed QUICKI and testosterone were independent predictors of IIEF-5 score. Furthermore, the incidence of IR was correlated with the severity of ED.Conclusions
Compared with other CVFs, IR was found as the most prevalent in our subjects. Besides, IR was independently associated with ED and its severity, suggesting an adverse effect of insulin resistance on erectile function. 相似文献127.
128.
Alphonse Ouédraogo Alfred B. Tiono Désiré Kargougou Jean Baptiste Yaro Esperance Ouédraogo Youssouf Kaboré David Kangoye Edith C. Bougouma Adama Gansane Noelie Henri Amidou Diarra Souleymane Sanon Issiaka Soulama Amadou T. Konate Nora L. Watson Valerie Brown Jenny Hendriks Maria Grazia Pau Isabella Versteege Edison Wiesken Jerald Sadoff Issa Nebie Sodiomon B. Sirima 《PloS one》2013,8(11)
Background
Ad35.CS.01 is a pre-erythrocytic malaria candidate vaccine. It is a codon optimized nucleotide sequence representing the P. falciparum circumsporozoite (CS) surface antigen inserted in a replication deficient Adenovirus 35 backbone. A Phase 1a trial has been conducted in the USA in naïve adults and showed that the vaccine was safe. The aim of this study is to assess the safety and immunogenicity of ascending dosages in sub Saharan Africa.Methods
A double blind, randomized, controlled, dose escalation, phase Ib trial was conducted in a rural area of Balonghin, the Saponé health district (Burkina Faso). Forty-eight healthy adults aged 18-45 years were randomized into 4 cohorts of 12 to receive three vaccine doses (day 0, 28 and 84) of 109, 1010, 5X1010, 1011 vp of Ad35.CS.01 or normal saline by intra muscular injection. Subjects were monitored carefully during the 14 days following each vaccination for non serious adverse events. Severe and serious adverse events were collected throughout the participant study duration (12 months from the first vaccination). Humoral and cellular immune responses were measured on study days 0, 28, 56, 84, 112 and 140.Results
Of the forty-eight subjects enrolled, forty-four (91.7%) received all three scheduled vaccine doses. Local reactions, all of mild severity, occurred in thirteen (27.1%) subjects. Severe (grade 3) laboratory abnormalities occurred in five (10.4%) subjects. One serious adverse event was reported and attributed to infection judged unrelated to vaccine. The vaccine induced both antibody titers and CD8 T cells producing IFNγ and TNFα with specificity to CS while eliciting modest neutralizing antibody responses against Ad35.Conclusion
Study vaccine Ad35.CS.01 at four different dose levels was well-tolerated and modestly immunogenic in this population. These results suggest that Ad35.CS.01 should be further investigated for preliminary efficacy in human challenge models and as part of heterologous prime-boost vaccination strategies.Trial Registration
ClinicalTrials.gov NCT01018459 http://clinicaltrials.gov/ct2/show/NCT01018459 相似文献129.
Yu-Ling Tu Su-Wei Chang Hui-Ju Tsai Li-Chen Chen Wen-I Lee Man-Chin Hua Ju-Hui Cheng Liang-Shiou Ou Kuo-Wei Yeh Jing-Long Huang Tsung-Chieh Yao for the PATCH study group 《PloS one》2013,8(11)
Background
Total serum immunoglobulin (IgE) test is usually performed to aid in the diagnosis of allergic diseases, but its reference values may vary among people of different ethnic backgrounds.Objectives
To establish reference values of total IgE in Asian children and to assess their significance in the diagnosis of atopy and allergic diseases.Study design
1321 Asian children aged 5-18 years in the Prediction of Allergies in Taiwanese CHildren (PATCH) study, a population-based cohort, were evaluated for total and specific IgE by ImmunoCAP and Phadiatop Infant, respectively.Results
Male, atopy, allergic diseases, recent symptoms of upper respiratory infection, and lower FEV1/FVC, were associated with higher total IgE levels in univariate analyses. Multivariate analysis revealed that atopy was the single most important determinant explaining 66.1% of the variability of total IgE levels in this population. The area under the receiver-operator characteristic (ROC) curve of total IgE for diagnosing atopy, asthma, rhinitis, and eczema were 0.92, 0.72, 0.70, and 0.70, respectively. The sensitivity, specificity, and positive and negative predictive values of total IgE at the optimal cutoff of 77.7 kU/L on the ROC curve for diagnosing atopy were 82.3%, 87.1%, 89.5%, and 78.6%, respectively. The corresponding values using the upper 95% CI of total IgE (164.3 kU/L) in non-atopic children were 61.2%, 95.0%, 94.3%, and 64.6%, respectively; whereas a customary cutoff (100 kU/L) provided accuracy between that of the aforementioned two cutoffs. Total IgE at the cutoff of 77.7 kU/L provided modest sensitivity and specificity (49.0%-78.3%) for diagnosing allergic diseases, but had high negative predictive values (84.2%-97.9%).Conclusions
Total serum IgE discriminates Asian children with and without atopy independent of allergic symptoms, with an optimal cutoff of 77.7 kU/L. The study confirms the insufficient diagnostic accuracy of total IgE alone to detect allergic diseases, but low total IgE levels may help exclude allergic diseases. 相似文献130.
采用黑暗摇瓶发酵和蓝光照射静置培养的两步培养法,进行蛹虫草(Cordyceps militaris L.)液体发酵产类胡萝卜素的蓝光诱导。结果表明蛹虫草在2d的黑暗培养和5d的蓝光照射静置培养后,其类胡萝卜素的含量可达到最高值558.4μg/gFW。而以黑暗摇瓶培养2d后,进行不同时间的蓝光照射静置培养。结果表明,蓝光照射最初2d,蛹虫草类胡萝卜素含量变化不明显,随后快速增加,并在第5天达到最大值558.4μg/gFW,随后类胡萝卜素的含量并无明显变化。通过研究解决了蛹虫草液体发酵产类胡萝卜素的培养过程中蓝光的给光问题。 相似文献