全文获取类型
收费全文 | 11609篇 |
免费 | 836篇 |
国内免费 | 8篇 |
出版年
2024年 | 10篇 |
2023年 | 43篇 |
2022年 | 115篇 |
2021年 | 235篇 |
2020年 | 196篇 |
2019年 | 238篇 |
2018年 | 375篇 |
2017年 | 315篇 |
2016年 | 495篇 |
2015年 | 772篇 |
2014年 | 826篇 |
2013年 | 888篇 |
2012年 | 1065篇 |
2011年 | 992篇 |
2010年 | 651篇 |
2009年 | 567篇 |
2008年 | 761篇 |
2007年 | 727篇 |
2006年 | 582篇 |
2005年 | 558篇 |
2004年 | 528篇 |
2003年 | 455篇 |
2002年 | 372篇 |
2001年 | 158篇 |
2000年 | 115篇 |
1999年 | 101篇 |
1998年 | 68篇 |
1997年 | 46篇 |
1996年 | 37篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1966年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Hye Ja Lee Mi Kyung Park Eun Ji Lee Chang Hoon Lee 《The international journal of biochemistry & cell biology》2013,45(12):2801-2807
Epithelial-mesenchymal-transition (EMT) is a key event for tumor cells to initiate metastasis which lead to switching of E-cadherin to N-cadherin. Resolvins are known to promote the resolution of inflammation and phagocytosis of macrophages. However, the role of resolvins in EMT of cancer is not known. Therefore, we examined the effects of resolvins on transforming growth factor, beta 1 (TGF-β1)-induced EMT. Expression of E-cadherin and N-cadherin in A549 lung cancer cells was evaluated by Western blot and confocal microscopy. Involvement of lipoxin A4 receptor/formyl peptide receptor 2 (ALX/FPR2) was examined by gene silencing. TGF-β1 induced expression of N-cadherin in A549 lung cancer cells, and resolvin D1 and D2 inhibited the expression of N-cadherin at low concentrations (1–100 nM). Resolvin D1 and D2 also suppressed the expression of zinc finger E-box binding homeobox 1 (ZEB1). The effects of resolvin D1 and D2 were confirmed in other lung cancer cell lines such as H838, H1299, and H1703. Resolvin D1 and D2 did not affect the proliferation of A549 lung cancer cells. Resolvin D1 and D2 also suppressed the TGF-β1-induced morphological change. Resolvin D1 and D2 also inhibited the TGF-β1-induced migration and invasion of A549 cells. Resolvin D1 is known to act via ALX/FPR2 and GPR32. Thus, we examined the involvement of ALX/FPR2 and GPR32 in the suppressive effects of resolvin D1 on TGF-β1-induced EMT of A549 cells. Gene silencing of ALX/FPR2 and GPR32 blocked the action of resolvin D1. Overexpression of ALX/FPR2 or GPR32 increased the effects of resolvin D1. These results suggest that resolvin D1 inhibited TGF-β1-induced EMT via ALX/FPR2 and GPR32 by reducing the expression of ZEB1. 相似文献
102.
Silkworm hemolymph (SH) was found to exhibit anti-apoptotic activities in mammalian and insect cell systems. An anti-apoptotic mechanism of SH was investigated in a staurosporine-induced HeLa cell using flow cytometry, caspase assay, Immunoblot, and Immunochemistry. The addition of 5% SH to the medium resulted in lower intracellular activities of caspase-3 and caspase-9 after 0.6 μM of staurosporine treatment; however, SH did not directly inhibit the activities of those enzymes. This suggests SH inhibits the event upstream of these caspase activation steps, such as mitochondrial level events. We found from Immunoblot and Immunochemistry that cytochrome c release from the mitochondria was blocked by SH. SH also inhibited Bax translocation to the mitochondria. On the contrary, SH did not block the apoptosis when Bax is not involved in promoting apoptosis. With these results, we propose that SH protects mitochondria from apoptosis signal via blocking Bax translocation, and the subsequent apoptotic events are then inhibited. The inhibition of apoptosis using SH and its components may lead to new approaches for the minimization of cell death during commercial animal cell cultures. 相似文献
103.
Hyo Won Suh Sun-Hee Hyun So-Hyun Kim Seok-Young Lee Hyung-Kyoon Choi 《Process Biochemistry》2013,48(10):1581-1586
In this study, the effects of methyl jasmonate (MJ) and silver nitrate (SN) treatment on metabolic profiles and yields of phytosterols such as campesterol, stigmasterol, and β-sitosterol in whole plant cultures of Lemna paucicostata were investigated using gas chromatography–mass spectrometry coupled with multivariate statistical analysis. The MJ and SN treatments retarded the growth of L. paucicostata plants, while they enhanced the yields of three phytosterols, compared to control. Higher yields of phytosterols were attained at day 28 compared to day 42. Moreover, stigmasterol yield was the highest at 0.85 mg/g from day 28 plants grown under MJ + SN co-treated culture. Among the various metabolites, the levels of palmitic and stearic acids, which might participate in a defense mechanism, were higher in the MJ + SN condition than in control. To determine the optimal timing of MJ + SN addition, MJ + SN was added on days 21, 28, and 35 after inoculation. The total yield and productivity of phytosterol reached maximum levels when the MJ + SN was added at day 35. The highest productivity of stigmasterol (6.08 mg/L) was also achieved when MJ + SN was added on day 35. 相似文献
104.
Flavonoid glycosides are highly attractive targets due to their dominant roles in clinical, cosmetic production and in the food industry. In this research, an Escherichia coli strain bearing the reconstructed uridine-diphosphate glucose (UDP-glucose) pathway cassette and a putative glycosyltransferase from Arabidopsis thaliana, was developed as a host for the production of apigenin-7-O-β-d-glucoside (APG) and baicalein-7-O-β-d-glucoside (BCG) from exogenously supplied flavone aglycones (apigenin and baicalein, respectively). In order to improve the yield, genetic engineering of E. coli strains for optimization of intracellular UDP-glucose generation, as well as media optimization were carried out. The production was scaled up using a fed batch fermentation, and the maximal yield of products reached 90.88 μM (39.28 mg L?1) and 76.82 μM (33.19 mg L?1) of APG and BCG, respectively. And, the maximum bioconversion rate corresponded to 90.88% and 76.82% of apigenin and baicalein, respectively. 相似文献
105.
The intelligent mobile robot with sensors and image processing embedded system combines the suction and aerodynamic attraction to achieve good balance between strong adhesion force and high mobility. Experimental results showed that the robot can move upward on the wall at the speed of 2.9 m/min and carry 5 kg payload in addition to 2.5 kg self-weight, which record the highest payload capacity among climbing robots of similar size. It also implements object detection ability using effective color transform and segmentation technique for the exact target detection on the wall using a embedded camera system, communication module and several active sensors. 相似文献
106.
Joon-Goo Jung Yong Jae Lee Natarajan Velmurugan Young-Joon Ko Hyang-Sim Lee Ki Jun Jeong 《Journal of industrial microbiology & biotechnology》2013,40(7):705-713
For effective control of foot-and-mouth disease (FMD), the development of rapid diagnostic systems and vaccines are required against its etiological agent, FMD virus (FMDV). To accomplish this, efficient large-scale expression of the FMDV VP1 protein, with high solubility, needs to be optimized. We attempted to produce high levels of a serotype O FMDV VP1 epitope in Escherichia coli. We identified the subtype-independent serotype O FMDV VP1 epitope sequence and used it to construct a glutathione S-transferase (GST) fusion protein. For efficient production of the FMDV VP1 epitope fused to GST (VP1e–GST), four E. coli strains and three temperatures were examined. The conditions yielding the greatest level of VP1e–GST with highest solubility were achieved with E. coli BL21(DE3) at 25 °C. For high-level production, fed-batch cultures were conducted in 5-l bioreactors. When cells were induced at a high density and complex feeding solutions were supplied, approximately 11 g of VP1e–GST was obtained from a 2.9-l culture. Following purification, the VP1 epitope was used to immunize rabbits, and we confirmed that it induced an immune response. 相似文献
107.
Koeun Han Hee-Jin Jeong Joohee Sung Young Soo Keum Myeong-Cheoul Cho Jeong-Han Kim Jin-Kyung Kwon Byung-Dong Kim Byoung-Cheorl Kang 《Molecular breeding : new strategies in plant improvement》2013,31(3):537-548
Pungency in pepper (Capsicum annuum L.) has unique characteristics due to the alkaloid compound group, capsaicinoids, which includes capsaicin. Although capsaicinoids have been proved to have pharmacological and physiological effects on human health, the application of capsaicinoids has been limited because of their pungency. Capsinoids found in non-pungent peppers share closely related structures with capsaicinoids and show similar biological effects. Previous studies demonstrated that mutations in the p-AMT gene were related to the production of capsinoids; however, the pathway of capsinoid synthesis has not yet been fully elucidated. In this study, we performed genetic analysis to determine the mechanism of capsinoid synthesis using a F6 recombinant inbred line population. In this population, the presence/absence of capsinoids co-segregated with the genotype of the Pun1 locus, without exception. In addition, we screened the patterns of capsinoid synthesis and the correlation between the Pun1 locus and capsinoid synthesis in p-AMT mutant accessions. In Capsicum germplasms, we selected amino-acid-substituted mutants in the PLP binding domain of the p-AMT gene. Capsinoids were not synthesized with the recessive pun1 gene, regardless of the p-AMT genotype, and no relationship was found between p-AMT mutant type and capsinoid content. We concluded that the Pun1 gene, which is responsible for capsaicinoid synthesis, also controls capsinoid synthesis. 相似文献
108.
Jaekwang Jeong Ivonne Lisinski Anil K. G. Kadegowda Hyunsu Shin F. B. Peter Wooding Brian R. Daniels Jerome Schaack Ian H. Mather 《Traffic (Copenhagen, Denmark)》2013,14(9):974-986
Milk lipid is secreted by a unique process, during which triacylglycerol droplets bud from mammary cells coated with an outer bilayer of apical membrane. In all current schemes, the integral protein butyrophilin 1A1 (BTN) is postulated to serve as a transmembrane scaffold, which interacts either with itself or with the peripheral proteins, xanthine oxidoreductase (XOR) and possibly perilipin‐2 (PLIN2), to form an immobile bridging complex between the droplet and apical surface. In one such scheme, BTN on the surface of cytoplasmic lipid droplets interacts directly with BTN in the apical membrane without binding to either XOR or PLIN2. We tested these models using both biochemical and morphological approaches. BTN was concentrated in the apical membrane in all species examined and contained mature N‐linked glycans. We found no evidence for the association of unprocessed BTN with intracellular lipid droplets. BTN‐enhanced green fluorescent protein was highly mobile in areas of mouse milk‐lipid droplets that had not undergone post‐secretion changes, and endogenous mouse BTN comprised only 0.5–0.7% (w/w) of the total protein, i.e. over 50‐fold less than in the milk‐lipid droplets of cow and other species. These data are incompatible with models of milk‐lipid secretion in which BTN is the major component of an immobile global adhesive complex and suggest that interactions between BTN and other proteins at the time of secretion are more transient than previously predicted. The high mobility of BTN in lipid droplets marks it as a potential mobile signaling molecule in milk . 相似文献
109.
The dairy industry is a multi-billion dollar industry catering the nutritional needs of all age groups globally through the supply of milk. Clinical mastitis has a severe impact on udder tissue and is also an animal welfare issue. Moreover, it significantly reduces animal value and milk production. Mammary tissue damage reduces the number and activity of epithelial cells and consequently contributes to decreased milk production. The high incidence, low cure rate of this highly economic and sometimes deadly disease is an alarming for dairy sector as well as policy makers. Bovine mammary epithelial cells (MECs) and their stem cells are very important in milk production and bioengineering. The adult mammary epithelium consists of two main cell types; an inner layer of luminal epithelial cells, which produce the milk during lactation, and an outer layer of myoepithelial cells resting on a basement membrane, which are responsible for pushing the milk through the ductal network to the teat cistern. Inner layer of columner/luminal cells of bovine MECs, is characterized by cytokeratin18, 19 (CK18, CK19) and outer layer such as myoepithelial cells which are characterized by CK14, α-smooth muscle actin (α-SMA) and p63. Much work has been done in mouse and human, on mammary gland stem cell research, particularly in cancer therapy, but stem cell research in bovine is still in its infancy. Such stem/progenitor cell discoveries in human and mouse mammary gland bring some hope for application in bovines. These progenitors may be therapeutically adopted to correct the structural/cytological defects in the bovine udder due to mastitis. In the present review we focused on various kinds of stem/progenitor cells which can have therapeutic utility and their possibilities to use as a potential stem cell therapy in the management of bovine post-mastitis damage in orders to restore milk production. The possibilities of bovine mammary stem cell therapy offers significant potential for regeneration of tissues that can potentially replace/repair diseased and damaged tissue through differentiation into epithelial, myoepithelial and/or cuboidal/columnar cells in the udder with minimal risk of rejection and side effects. 相似文献
110.
Chung-Hwa Park Si Hyun Bae Hee Yeon Kim Ja Kyung Kim Eun Sun Jung Ho Jong Chun Myeong Jun Song Sung-Eun Lee Seok Goo Cho Jong Wook Lee Jong Young Choi Seung Kew Yoon Nam Ik Han Young Sok Lee 《Cytotherapy》2013,15(12):1571-1579
Background aimsMany rodent experiments and human studies on stem cell therapy have shown promising therapeutic approaches to liver diseases. We investigated the clinical outcomes of five patients with liver failure of various causes who received autologous CD34-depleted bone marrow-derived mononuclear cell (BM-MNC) transplantation, including mesenchymal stromal cells, through the hepatic artery.MethodsCD34-depleted BM-MNCs were obtained from five patients waiting for liver transplantation by bone marrow aspiration and using the CliniMACS CD34 Reagent System (Miltenyi Biotech, Bergisch Gladbach, Germany), and autologous hepatic artery infusion was performed. The causes of hepatic decompensation were hepatitis B virus (HBV), hepatitis C virus (HCV), propylthiouracil-induced toxic hepatitis and Wilson disease.ResultsSerum albumin levels improved 1 week after transplantation from 2.8 g/dL, 2.4 g/dL, 2.7 g/dL and 1.9 g/dL to 3.3 g/dL, 3.1 g/dL, 2.8 g/dL and 2.6 g/dL. Transient liver elastography data showed some change from 65 kPa, 33 kPa, 34.8 kPa and undetectable to 46.4 kPa, 19.8 kPa, 29.1 kPa and 67.8 kPa at 4 weeks after transplantation in a patient with Wilson disease, a patient with HCV, and two patients with HBV. Ascites decreased in two patients. One of the patients with HBV underwent liver transplantation 4 months after the infusion, and the hepatic progenitor markers (cytokeratin [CD]-7, CD-8, CD-9, CD-18, CD-19, c-Kit and epithelial cell adhesion molecule [EpCAM]) were highly expressed in the explanted liver.ConclusionsSerum albumin levels, liver stiffness, liver volume, subjective healthiness and quality of life improved in the study patients. Although these findings were observed in a small population, the results may suggest a promising future for autologous CD34-depleted BM-MNC transplantation as a bridge to liver transplantation in patients with liver failure. 相似文献