全文获取类型
收费全文 | 1727篇 |
免费 | 38篇 |
国内免费 | 4篇 |
专业分类
1769篇 |
出版年
2024年 | 15篇 |
2023年 | 15篇 |
2022年 | 72篇 |
2021年 | 82篇 |
2020年 | 54篇 |
2019年 | 95篇 |
2018年 | 96篇 |
2017年 | 51篇 |
2016年 | 78篇 |
2015年 | 79篇 |
2014年 | 102篇 |
2013年 | 131篇 |
2012年 | 151篇 |
2011年 | 123篇 |
2010年 | 59篇 |
2009年 | 51篇 |
2008年 | 60篇 |
2007年 | 53篇 |
2006年 | 40篇 |
2005年 | 45篇 |
2004年 | 36篇 |
2003年 | 39篇 |
2002年 | 32篇 |
2001年 | 20篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1967年 | 5篇 |
排序方式: 共有1769条查询结果,搜索用时 18 毫秒
971.
Saeed Mohammadian Haftcheshmeh Amir Tajbakhsh Mohaddese Kazemi Seyed-Alireza Esmaeili Fatemeh Mardani Mostafa Fazeli Amirhossein Sahebkar 《Journal of cellular physiology》2019,234(2):1179-1189
The CD7 antigen is a member of the immunoglobulin superfamily that expresses on the surface of all thymocytes, a majority of mature T cells, and also natural killer cells. Interestingly, under physiological and different pathological conditions, the loss of CD7 antigen occurred in the subset of CD4+ memory T cells. Various functions have been proposed for CD7, including its role in the activation and intercellular adhesiveness of T cells. Several studies indicate that the number of CD4+CD7− T cells increases in diseases such as chronic inflammation and T-cell malignancies, these being skin inflammatory lesions. Therefore, this can be useful for the diagnosis of cancer cells, especially with reference to blood origin, treatment monitoring, and establishment of new therapies. Therefore, a comprehensive review could be useful to increase our knowledge about the clinical importance of these cells in human disease. 相似文献
972.
973.
974.
Elsaadany Mostafa Yan Karen Chang Yildirim-Ayan Eda 《Biomechanics and modeling in mechanobiology》2017,16(3):1049-1063
Biomechanics and Modeling in Mechanobiology - Successful tissue engineering and regenerative therapy necessitate having extensive knowledge about mechanical milieu in engineered tissues and the... 相似文献
975.
Over the past few years, ultrasonic techniques are increasingly used to determine bubble size distribution in gas–liquid two‐phase systems. However, the development of a precise and efficient measuring system is very challenging because bubbles are dynamic and unstable relative to time and space in a moving fluid, thus hindering an accurate validation of the measuring system. Therefore, this study examined the possibility of using artificial bubbles to establish an ultrasonic measuring system. The main concept for this study involved developing an ultrasound‐based measuring system with the aid of a certain type of artificial bubbles. The developed system was subsequently adapted to the bypass pipeline of a propagator to demonstrate the reliability of this concept. The results indicated that the established system could measure a microbubble size distribution with a root mean squared error of validation that corresponded to 0.1243 % v/v. Additionally, the estimates of real bubble measurement agreed well with the reference method. Thus, this study demonstrated that the developed system could be a potential method to determine bubble size distributions in gas–liquid two‐phase systems. 相似文献
976.
Wenping Luo Linghuan Zhang Bo Huang Hongmei Zhang Yan Zhang Fugui Zhang Panpan Liang Qiuman Chen Qianyu Cheng Dongmei Tan Yi Tan Jinlin Song Tianyu Zhao Rex C. Haydon Russell R. Reid Hue H Luu Michael J. Lee Mostafa El Dafrawy Ping Ji Tong-Chuan He Liming Gou 《Journal of cellular and molecular medicine》2021,25(5):2666-2678
Teeth arise from the tooth germ through sequential and reciprocal interactions between immature epithelium and mesenchyme during development. However, the detailed mechanism underlying tooth development from tooth germ mesenchymal cells (TGMCs) remains to be fully understood. Here, we investigate the role of Wnt/β-catenin signalling in BMP9-induced osteogenic/odontogenic differentiation of TGMCs. We first established the reversibly immortalized TGMCs (iTGMCs) derived from young mouse mandibular molar tooth germs using a retroviral vector expressing SV40 T antigen flanked with the FRT sites. We demonstrated that BMP9 effectively induced expression of osteogenic markers alkaline phosphatase, collagen A1 and osteocalcin in iTGMCs, as well as in vitro matrix mineralization, which could be remarkably blunted by knocking down β-catenin expression. In vivo implantation assay revealed that while BMP9-stimulated iTGMCs induced robust formation of ectopic bone, knocking down β-catenin expression in iTGMCs remarkably diminished BMP9-initiated osteogenic/odontogenic differentiation potential of these cells. Taken together, these discoveries strongly demonstrate that reversibly immortalized iTGMCs retained osteogenic/odontogenic ability upon BMP9 stimulation, but this process required the participation of canonical Wnt signalling both in vitro and in vivo. Therefore, BMP9 has a potential to be applied as an efficacious bio-factor in osteo/odontogenic regeneration and tooth engineering. Furthermore, the iTGMCs may serve as an important resource for translational studies in tooth tissue engineering. 相似文献
977.
N.K. Abd El-Aziz A.A Gharib E.A.A. Mohamed A.H. Hussein 《Journal of applied microbiology》2021,130(5):1630-1644
978.
Ghada S. Hassan Shahenda M. El-Messery Fatmah A.M. Al-Omary Hussein I. El-Subbagh 《Bioorganic & medicinal chemistry letters》2012,22(20):6318-6323
A novel series of 2-acetamido- or 2-propanamido-4-(4-substituted phenyl)-1,3-thiazoles (11–34) was designed and synthesized. Compounds were subjected to National Cancer Institute (NCI) in vitro assessment for their antitumor activity, at a single dose of 10 μM. Most of the investigated compounds exhibited broad-spectrum antitumor activity. Compounds 19 and 28 believed to be the most active members in this study, with MG-MID GI50, TGI, and LC50 values of 2.8, 11.4, 44.7; and 3.3, 13.1, 46.8, respectively. Compounds 19 and 28 proved to be nine and sevenfold more active than the standard antitumor drug 5-FU, respectively. 相似文献
979.
Objective In order to examine whether chronic exposure to natural sour gas containing sulfur compounds act as natural selection force
on genetic polymorphisms of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1), the present study was done. Methods The study was performed on two groups of healthy individuals of Masjid-i-Sulaiman (Khozestan province, southwest of Iran)
citizens with the mean ages of 47.5 ± 12.4 (36 male and 58 female) and 16.3 ± 2.4 (47 male and 140 female) that were considered
as first and second generation, respectively. The GSTT1 and GSTM1 genotypes were determined using a PCR-based method. Results The genotypic frequencies of GSTM1 did not change significantly (χ2 = 0.085, df = 1, P = 0.770). The frequency of the GSTT1 null genotype was 52.1% in the first generation and reached to 36.4% in the second generation. There was significant difference
between two generations for the GSTT1 polymorphism (χ2 = 6.397, df = 1, P = 0.011). Conclusion It was suggested that the GSTT1 polymorphism may be under natural selection because of probably favored ability of GSTT1-active genotype to survival and reproduction. 相似文献
980.
Mostafa Khanamani Yaghoub Fathipour Hamidreza Hajiqanbar Amin Sedaratian 《Experimental & applied acarology》2014,62(2):241-252
The blue tick, Rhipicephalus microplus, threatens cattle production in most tropical and subtropical areas of the world. Delayed skin hypersensitivity reactions are thought to cause Nguni cattle to be more resistant to R. microplus than Bonsmara cattle yet the cellular mechanisms responsible for these differences have not been classified. Tick counts and inflammatory cell infiltrates in skin biopsies from feeding sites of adult R. microplus ticks were determined in 9-month-old Nguni and Bonsmara heifers to determine the cellular mechanisms responsible for tick immunity. Nguni heifers (1.7 ± 0.03) had lower (P < 0.05) tick counts than the Bonsmaras (2.0 ± 0.03). Parasitized sites in Nguni heifers had higher counts of basophils, mast and mononuclear cells than those in the Bonsmara heifers. Conversely, parasitized sites in Nguni heifers had lower neutrophil and eosinophil counts than those in the Bonsmara heifers. Tick count was negatively correlated with basophil and mast cell counts and positively correlated with eosinophil counts in both breeds. In the Bonsmara breed, tick count was positively correlated with mononuclear cell counts. Cellular responses to adult R. microplus infestations were different and correlated with differences in tick resistance in Nguni and Bonsmara cattle breeds. It is essential to further characterise the molecular composition of the inflammatory infiltrate elicited by adult R. microplus infestation to fully comprehend immunity to ticks in cattle. 相似文献