全文获取类型
收费全文 | 2804篇 |
免费 | 165篇 |
国内免费 | 5篇 |
出版年
2023年 | 27篇 |
2022年 | 82篇 |
2021年 | 171篇 |
2020年 | 70篇 |
2019年 | 95篇 |
2018年 | 113篇 |
2017年 | 90篇 |
2016年 | 99篇 |
2015年 | 140篇 |
2014年 | 166篇 |
2013年 | 191篇 |
2012年 | 196篇 |
2011年 | 205篇 |
2010年 | 95篇 |
2009年 | 85篇 |
2008年 | 113篇 |
2007年 | 99篇 |
2006年 | 102篇 |
2005年 | 71篇 |
2004年 | 53篇 |
2003年 | 57篇 |
2002年 | 50篇 |
2001年 | 56篇 |
2000年 | 41篇 |
1999年 | 42篇 |
1998年 | 9篇 |
1997年 | 14篇 |
1995年 | 9篇 |
1994年 | 22篇 |
1993年 | 14篇 |
1992年 | 35篇 |
1991年 | 27篇 |
1990年 | 35篇 |
1989年 | 24篇 |
1988年 | 24篇 |
1987年 | 25篇 |
1986年 | 19篇 |
1985年 | 28篇 |
1984年 | 21篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1974年 | 15篇 |
1973年 | 11篇 |
1972年 | 9篇 |
1971年 | 8篇 |
排序方式: 共有2974条查询结果,搜索用时 468 毫秒
111.
Mahmud Hussain Dustin Lockney Ruqi Wang Nimish Gera Balaji M. Rao 《Biotechnology progress》2013,29(1):237-246
Immunoaffinity separation of large multivalent species such as viruses is limited by the stringent elution conditions necessary to overcome their strong and highly avid interaction with immobilized affinity ligands on the capture surface. Here we present an alternate strategy that harnesses the avidity effect to overcome this limitation. Red clover necrotic mosaic virus (RCNMV), a plant virus relevant to drug delivery applications, was chosen as a model target for this study. An RCNMV binding protein (RBP) with modest binding affinity (KD ~100 nM) was generated through mutagenesis of the Sso7d protein from Sulfolobus solfataricus and used as the affinity ligand. In our separation scheme, RCNMV is captured by a highly avid interaction with RBP immobilized on a nickel surface through a hexahistidine (6xHis) tag. Subsequently, disruption of the multivalent interaction and release of RCNMV is achieved by elution of RBP from the nickel surface. Finally, RCNMV is separated from RBP by exploiting the large difference in their molecular weights (~8 MDa vs. ~10 kDa). Our strategy not only eliminates the need for harsh elution conditions, but also bypasses chemical conjugation of the affinity ligand to the capture surface. Stable non‐antibody affinity ligands to a wide spectrum of targets can be generated through mutagenesis of Sso7d and other hyperthermophilic proteins. Therefore, our approach may be broadly relevant to cases where capture of large multivalent species from complex mixtures and subsequent release without the use of harsh elution conditions is necessary. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013 相似文献
112.
Atika?MansoorEmail author Lubna?Ali Noor-ul?Sabah Asraf?Hussain?Hashmi Mohammad?Haroon?Khan Syed?Ali?Raza?Kazmi Nafees?Ahmad Saima?Siddiqi Khalid?Mehmood?Khan 《Virology journal》2013,10(1):352
Background
Hepatitis C virus (HCV) is a major cause of liver cirrhosis and hepatocellular carcinoma and infects about 3% world population. Response to interferon therapy depends upon the genotype of the virus and factors associated with the host. Despite a good response to interferon therapy, a considerable number of genotype 3a infected patients remains unalleviated.Results
In total forty-nine patients including twenty-five non-responders (non-SVR) and twenty-four responders (SVR) were recruited. Patients were tested for viral status at different intervals and the isolated RNA was sequenced for the NS5A region in both groups. The comparison of PKRBD of HCV between the SVR and non-SVR patients did not confirm any significant difference in the number of mutations. However, when the sequence downstream to the PKRBD of NS5A was compared, two important statistically significant mutations were observed; at positions 2309 (Ala to Ser) and 2326 (Gly to Ala). These mutations were then analysed for tertiary protein structure and important structural changes were observed. Statistically significant difference was also observed when age groups of patients were compared; younger patients showed better response than the older ones.Conclusions
The region between PKRBD and IRRDR may be important for prediction of response to IFN therapy for genotype 3a. ISDR and PKRBD have not shown any involvement in treatment response. Further functional analyses of these findings can help in understanding the involvement of the NS5A region in interferon treatment of HCV-3a infected patients.113.
114.
115.
Sanghamitra Pati Mohammad Akhtar Hussain Abhimanyu Singh Chauhan Diptimayee Mallick Sukdev Nayak 《Cancer epidemiology》2013,37(6):973-978
Cancer is a leading cause of mortality worldwide. Early diagnosis and treatment of cancer may curb the growing burden of the disease. Understanding cancer patients’ navigation pathways for seeking treatment is important in order to facilitate early diagnosis and treatment. With this background we conducted a hospital-based cross-sectional study comprising 68 randomly selected cancer inpatients in a tertiary cancer specialty hospital in Odisha, India, to explore the treatment-seeking pathways of the cancer patients and the barriers and enablers in seeking treatment. Financial constraint is one of the major reasons for the delay in accessing treatment, even when patients are suspected of or diagnosed with cancer. Low awareness of the presenting signs and symptoms of cancer and limited knowledge of the availability of cancer diagnosis and treatment facilities are major factors contributing to delay. Family and friends’ support is found to be the major enabling factor toward seeking treatment. Generation of awareness of cancer among the general population and primary-care practitioners – including those in alternative systems of medicine – is important. Information on diagnostic and treatment services appears to be a felt need. 相似文献
116.
117.
Yongqiang Liu Fuqian Yang Hongtie Pu Junping Su Zongjiang Liu Khalid Hussain Dhiloo Zhongyue Wang 《PloS one》2016,11(11)
Grape phylloxera, Daktulosphaira vitifoliae (Fitch) (Hemiptera, Phylloxeridae), is a very destructive insect pest of grapevines. Intercropping of Achyranthes bidentata Blume (f. Amaranthaceae) and Vitis spp. grapevines can be useful to control this pest. In the present study, the toxicity of 22 compounds, known to be present in A. bidentata, to grape phylloxera was evaluated. All treatments were toxic towards grape phylloxera but the degree of toxicity differed between treatments. Among the 22 tested compounds, several of which proved toxic towards grape phylloxera. However β-ecdysterone had higher toxic effects against grape phylloxera, with LC50 values of 175.73 mg a.i. liter-1. In addition, we assessed the sublethal effects of LC10, LC20 and LC40 of β-ecdysterone on grape phylloxera. The fourth instar and adult developmental periods and total life span were significantly prolonged by LC40 of β-ecdysterone. Fecundity decreased when grape phylloxera were exposed to LC20 and LC40 of β-ecdysterone. In addition, LC40 of β-ecdysterone decreased the intrinsic rate of increase (rm) and the finite rate of increase (λ) and prolonged the population doubling time (DT). The net reproductive rate (R0) was significantly reduced by both the LC20 and LC40 β-ecdysterone treatments. Our results demonstrated that β-ecdysterone had higher toxic effects and significant sublethal effects on grape phylloxera, and showed potential control of grape phylloxera. 相似文献
118.
Ahtesham Hussain Mukesh Kumar Yadav Shambhunath Bose Jing-Hua Wang Dongwoo Lim Yun-Kyung Song Seong-Gyu Ko Hojun Kim 《PloS one》2016,11(11)
BackgroundObesity has become a major global health challenge due to its increasing prevalence, and the associated health risk. It is the main cause of various metabolic diseases including diabetes, hypertension, cardiovascular disease, stroke and certain forms of cancer.
Methods and Results
In the present study we evaluated the anti-obesity property of Daesiho-tang (DSHT), an herbal medicine, using high fat diet (HFD)-induced obese mice as a model. Our results showed that DSHT ameliorated body weight gain, decreased total body fat, regulated expression of leptin and adiponectin genes of adipose tissue and exerted an anti-diabetic effect by attenuating fasting glucose level and serum insulin level in HFD-fed animals. In addition, DSHT-treatment significantly reduced total cholesterol (TC), triglycerides (TG) and increased high density lipoprotein-cholesterol (HDL), glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) levels in serum and reduced deposition of fat droplets in liver. DSHT treatment resulted in significantly increased relative abundance of bacteria including Bacteroidetes, Bacteroidetes/Firmicutes ratio, Akkermansia Bifidobacterium., Lactobacillus, and decreased the level of Firmicutes. Using RT2 profiler PCR array, 39 (46%) genes were found to be differentially expressed in HFD-fed mice compared to normal control. However, normal gene expressions were restored in 36 (92%) genes of HFD-fed mice, when co-exposed to DSHT.Conclusion/Major Findings
The results of this study demonstrated that DSHT is an effective herbal formulation in attenuation of obesity in HFD-fed mice through alteration of gene expressions and modulation of intestinal microbiota. 相似文献119.
Md Dilshad Manzar Mohammad Muntafa Rajput Wassilatul Zannat Seithikurippu R. Pandi-Perumal Ahmed S. BaHammam M. Ejaz Hussain 《PloS one》2016,11(3)
Purpose
To study spontaneous K-complex (KC) densities during slow-wave sleep. The secondary objective was to estimate intra-non-rapid eye movement (NREM) sleep differences in KC density.Materials and Methods
It is a retrospective study using EEG data included in polysomnographic records from the archive at the sleep research laboratory of the Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia, India. The EEG records of 4459 minutes were used. The study presents a manual identification investigation of KCs in 17 healthy young adult male volunteers (age = 23.82±3.40 years and BMI = 23.42±4.18 kg/m2).Results
N3 had a higher KC density than N2 (Z = -2.485, p = 0.013) for all of the probes taken together. Four EEG probes had a higher probe-specific KC density during N3. The inter-probe KC density differed significantly during N2 (χ2 = 67.91, p < .001), N3 (χ2 = 70.62, p < .001) and NREM (χ2 = 68.50, p < .001). The percent distribution of KC decreased uniformly with sleep cycles.Conclusion
The inter-probe differences during N3 establish the fronto-central dominance of the KC density regardless of sleep stage. This finding supports one local theory of KC generation. The significantly higher KC density during N3 may imply that the neuro-anatomical origin of slow-wave activity and KC is the same. This temporal alignment with slow-wave activity supports the sleep-promoting function of the KC. 相似文献120.