全文获取类型
收费全文 | 6807篇 |
免费 | 386篇 |
国内免费 | 21篇 |
专业分类
7214篇 |
出版年
2024年 | 11篇 |
2023年 | 96篇 |
2022年 | 250篇 |
2021年 | 361篇 |
2020年 | 334篇 |
2019年 | 481篇 |
2018年 | 372篇 |
2017年 | 264篇 |
2016年 | 349篇 |
2015年 | 372篇 |
2014年 | 461篇 |
2013年 | 585篇 |
2012年 | 542篇 |
2011年 | 543篇 |
2010年 | 286篇 |
2009年 | 245篇 |
2008年 | 273篇 |
2007年 | 276篇 |
2006年 | 243篇 |
2005年 | 204篇 |
2004年 | 150篇 |
2003年 | 114篇 |
2002年 | 103篇 |
2001年 | 16篇 |
2000年 | 16篇 |
1999年 | 20篇 |
1998年 | 21篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 14篇 |
1992年 | 6篇 |
1991年 | 16篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 4篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1972年 | 4篇 |
排序方式: 共有7214条查询结果,搜索用时 15 毫秒
151.
152.
Tanhaeian Abbas Jaafari Mahmoud Reza Ahmadi Farajollah Shahriari Vakili‐Ghartavol Roghayyeh Sekhavati Mohammad Hadi 《Probiotics and antimicrobial proteins》2019,11(3):1034-1041
Probiotics and Antimicrobial Proteins - Nowadays, cancer remains a major cause of death affecting millions of people. Currently, the antimicrobial peptides (AMPs) as potent anticancer therapeutic... 相似文献
153.
154.
Oleanane-type triterpene is one of the most widespread triterpenes found in plants, together with the lupane type, and these two types often occur together in the same plant. Bruguiera gymnorrhiza (L.) Lamk. and Rhizophora stylosa Griff. (Rhizophoraceae) are known to produce both types of triterpenes. Four oxidosqualene cyclase cDNAs were cloned from the leaves of B. gymnorrhiza and R. stylosa by a homology-based PCR method. The ORFs of full-length clones termed BgbAS (2280 bp, coding for 759 amino acids), BgLUS (2286 bp, coding for 761 amino acids), RsM1 (2280 bp, coding for 759 amino acids) and RsM2 (2316 bp coding for 771 amino acids) were ligated into yeast expression plasmid pYES2 under the control of the GAL1 promoter. Expression of BgbAS and BgLUS in GIL77 resulted in the production of beta-amyrin and lupeol, suggesting that these genes encode beta-amyrin and lupeol synthase (LUS), respectively. Furthermore, RsM1 produced germanicol, beta-amyrin, and lupeol in the ratio of 63 : 33 : 4, whereas RsM2 produced taraxerol, beta-amyrin, and lupeol in the proportions 70 : 17 : 13. This result indicates that these are multifunctional triterpene synthases. Phylogenetic analysis and sequence comparisons revealed that BgbAS and RsM1 demonstrated high similarities (78-93%) to beta-amyrin synthases, and were located in the same branch as beta-amyrin synthase. BgLUS formed a new branch for lupeol synthase that was closely related to the beta-amyrin synthase cluster, whereas RsM2 was found in the first branch of the multifunctional triterpene synthase evolved from lupeol to beta-amyrin synthase. Based on these sequence comparisons and product profiles, we discuss the molecular evolution of triterpene synthases and the involvement of these genes in the formation of terpenoids in mangrove leaves. 相似文献
155.
Islam Mohammad Rakibul Yasir Fahim Antor Md. Rakib Hossain Turja Mahmudul Hassan Rahman Ashikur Khan Md. Rezaul Hoque Reza Md. Taslim 《Plasmonics (Norwell, Mass.)》2022,17(1):131-141
Plasmonics - This research illustrates a parametric study based on surface plasmon resonance of a slightly gold-coated photonic crystal fiber (PCF). In verifying sensing accuracy, the proposed... 相似文献
156.
157.
Alptekin Burcu Erfatpour Mohammad Mangel Dylan Pauli Duke Blake Tom Turner Hannah Lachowiec Jennifer Sherman Jamie Fischer Andreas 《Molecular breeding : new strategies in plant improvement》2022,42(10):1-15
Molecular Breeding - Maize amylose is a type of high value-added starch used for medical, food, and chemical applications. Mutations in the starch branching enzyme (SBEIIb), with recessive ae... 相似文献
158.
Elaheh Esmaeili Masoud Soleimani Mohammad Adel Ghiass Shadie Hatamie Saeed Vakilian Mahsa Soufi Zomorrod Negar Sadeghzadeh Manouchehr Vossoughi Simzar Hosseinzadeh 《Journal of cellular physiology》2019,234(8):13617-13628
While the differentiation factors have been widely used to differentiate mesenchymal stem cells (MSCs) into various cell types, they can cause harm at the same time. Therefore, it is beneficial to propose methods to differentiate MSCs without factors. Herein, magnetoelectric (ME) nanofibers were synthesized as the scaffold for the growth of MSCs and their differentiation into neural cells without factors. This nanocomposite takes the advantage of the synergies of the magnetostrictive filler, CoFe2O 4 nanoparticles (CFO), and piezoelectric polymer, polyvinylidene difluoride (PVDF). Graphene oxide nanosheets were decorated with CFO nanoparticles for a proper dispersion in the polymer through a hydrothermal process. After that, the piezoelectric PVDF polymer, which contained the magnetic nanoparticles, underwent the electrospun process to form ME nanofibers, the ME property of which has the potential to be used in areas such as tissue engineering, biosensors, and actuators. 相似文献
159.
160.
Maryam Vahdat-Lasemi Sara Hosseini Vahid Jajarmi Bahram Kazemi Mohammad Salehi 《Journal of cellular physiology》2019,234(8):13858-13866
miR-224 is associated with polycystic ovary syndrome (PCOS) that is an epidemic in reproductive age women. Most studies of miR-224 have focused on in vitro analyses, whereas the in vivo effects are not widely understood. In this study, we have conducted in silico analysis and found two potential miR-224 target genes, Ptx3 and Smad4 that have roles in folliculogenesis. Because patients with PCOS have decreased numbers of follicular cells related to cell apoptosis, we also investigated two apoptotic genes, Bax and Bcl2. We used the intraovarian injection method to deliver miR-224 into a mouse model. Histological examination of the ovaries was done by fluorescent microscope. Fertilization, cleavage, and developmental competence rates were counted under a stereomicroscope and compared between the studied groups. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis of miR-224 was conducted to determine the levels of the studied genes in the oocytes, cumulus cells, and blastocysts. The numbers of oocytes and fertilization rate indicated a higher apoptosis index ( p < 0.05) and increased numbers of degenerated embryos with irregular blastomeres and fragmented cytoplasm in the experimental group. RT-PCR results indicated a significant increase in miR-224 levels in the manipulated group. Of the four analyzed genes, Ptx3, Smad4, and Bcl2 had decreased levels in the transfected group, with increased Bax expression ( p < 0.05). This data showed that miR-224 negatively affected ovulation in the mouse model by decreasing Ptx3 and Smad4 expressions. The changes in Bcl2 and Bax expression levels, as apoptosis biomarkers, showed that apoptosis was a secondary outcome of the effect of miR-224. 相似文献