全文获取类型
收费全文 | 1139篇 |
免费 | 122篇 |
国内免费 | 67篇 |
专业分类
1328篇 |
出版年
2024年 | 5篇 |
2023年 | 17篇 |
2022年 | 34篇 |
2021年 | 50篇 |
2020年 | 42篇 |
2019年 | 51篇 |
2018年 | 67篇 |
2017年 | 34篇 |
2016年 | 60篇 |
2015年 | 71篇 |
2014年 | 75篇 |
2013年 | 81篇 |
2012年 | 97篇 |
2011年 | 96篇 |
2010年 | 59篇 |
2009年 | 59篇 |
2008年 | 57篇 |
2007年 | 49篇 |
2006年 | 47篇 |
2005年 | 27篇 |
2004年 | 25篇 |
2003年 | 32篇 |
2002年 | 26篇 |
2001年 | 26篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 3篇 |
排序方式: 共有1328条查询结果,搜索用时 0 毫秒
991.
Loss of rotational mobility of band 3 proteins in human erythrocyte membranes induced by antibodies to glycophorin A. 总被引:2,自引:1,他引:1 下载免费PDF全文
The effect of antibodies to glycophorin A on the rotational diffusion of band 3 in human erythrocyte membranes was investigated by transient dichrosim. Three antibodies that recognize different epitopes on the exofacial domain of glycophorin A all strongly reduce the rotational mobility of band 3. The effect is at most only weakly dependent on the distance of the epitope from the membrane surface. The degree of immobilization obtained with two of the antibodies, BRIC14 and R18, is very similar to that produced by antibodies to band 3 itself. Similar results were obtained with membranes stripped of skeletal proteins. Fab fragments and an antibody to glycophorin C had no effect on band 3 rotational mobility. These results rule out a mechanism whereby band 3 rotational immobilization results from enhanced interactions with the membrane skeleton that are mediated by a conformational change in glycophorin A. Rather, they strongly indicate that the antibodies to glycophorin A cross-link existing band 3-glycophorin A complexes that have lifetimes that are long compared with the millisecond time scale of the transient dichroism measurements. 相似文献
992.
Zili Kong Wenshan Lv Yunyang Wang Yajing Huang Kui Che Huiqi Nan Yu Xin Jiaxuan Wang Jintao Chen Yangang Wang Jingwei Chi 《Journal of biochemical and molecular toxicology》2023,37(10):e23445
Diabetic nephropathy (DN) affects around 40% of people with diabetes, the final outcome of which is end-stage renal disease. The deficiency of autophagy and excessive oxidative stress have been found to participate in the pathogenesis of DN. Sinensetin (SIN) has been proven to have strong antioxidant capability. However, the effect of SIN on DN has not been studied. We examined the effect of SIN on cell viability and autophagy in the podocyte cell line, MPC5 cells, treated with high glucose (HG). For in vivo studies, DN mice models were established by intraperitoneal injected with streptozotocin (40 mg/kg) for 5 consecutive days and fed with a 60% high-fat diet, and SIN was given (10, 20, and 40 mg/kg) for 8 weeks via intraperitoneal injection. The results showed that SIN could protect MPC5 cells against HG-induced damage and significantly improve the renal function of DN mice. Moreover, SIN remarkably restored the autophagy activity of MPC5 cells which was inhibited under HG conditions. Consistent with this, SIN efficiently improved autophagy in the kidney tissue of DN mice. In brief, our findings demonstrated the protective effect of SIN on DN via restoring the autophagic function, which might provide a basis for drug development. 相似文献
993.
The distal aspect of the housefly ommatidium was surveyed by the scanning electron microscope. Attention was directed to the somal eminence of the superior central cell and the lens to large pigment cell junction. The underside of each lens facet exhibits six hexagonally arranged incisures. Into each of these indentations are fitted several large pigment cells. This hexagonal indentation appears to be a tenacious anchorage. Two corneal pigment cells laterally encircle the pseudocone and at their proximal extension they enclose the Semper cells and neck of the retinula. The somal eminence of the superior central cell is about 10 mum from the base of the corneal pigment cell enclosure. Micrographs were used to construct a diagram of the ommatidium above the basement membrane. Suggestions are made as to the functional correlates of the observed ommatidial structures. 相似文献
994.
The paper presents 21Fusarium species occurring in Poland on the field crops /mostly on cereals, maize, potato and Papilionaceae plants/, woody plants, grasses, vegetables and ornamentals as well as on kernels or seeds of these hosts and soils. Additionally the commonly observed symptoms on above-mentioned plants and the informations about regions of the highest disease occurrence are added.However the paper results mainly from authors’ investigation on theFusarium species occurrence in Poland, it encloses also the available, post-war literature data on the fusariosis in Poland in the past.Majority ofFusarium species cited had been identified according to Nelson et al, taxonomic system. Comparative listing of the monographs / 1,11, 21/ is presented. 相似文献
995.
Fusarium graminearum KF-376 isolate was found to be able to form simultaneously three toxic metabolites: zearalenone (FF-2), deoxynivalenol (DON) and 15-acetyldeoxynivalenol (15-AcDON). Toxins were extracted with methanol — water 3:1 (v/v) and purified by liquid chromatography on charcoal — Kieselgel 60 column (preliminary) and Aluminiumoxid 90 column. Final separation of the metabolites was achived on Kieselgel 60 — Aluminiumoxid 90 column. 相似文献
996.
J Sroczyński E Che?mecka J Piotrowski M Snit 《Polski tygodnik lekarski (Warsaw, Poland : 1960)》1991,46(14-16):262-265
The study was aimed at analysing the epidemiological structure of patients with liver cirrhosis without HBsAg treated in 1980-1988. There were 231 of such cases in this period of time. The most frequent cause of liver cirrhosis in patients under 60 years of life was chronic alcoholism whereas 40% of the diagnosed liver cirrhosis in older persons was of unclear etiology. Patients complaints, clinical examinations, and results of the laboratory tests were analysed. The course of the disease was more severe in alcohol-produced liver cirrhosis leading to the haemorrhage from esophageal varices in 36%, and coma in 8% of cases. Alcohol-produced liver cirrhosis promoted other complications such as: cancer of the liver, hepato-renal syndrome or encephalopathy. Liver cirrhosis of unclear etiology in the elderly may be a consequence of the prolonged exposition to environmental pollutants. More severe course of alcohol-produced liver cirrhosis may depend on simultaneous action of two harmful factors: alcohol and environmental pollutants. 相似文献
997.
E Buschman R J Arceci J M Croop M Che I M Arias D E Housman P Gros 《The Journal of biological chemistry》1992,267(25):18093-18099
We have produced antibodies specific for the three P-glycoprotein (P-gp) isoforms encoded by the mouse mdr1, mdr2, and mdr3 genes. The anti-Mdr2 and anti-Mdr3 antibodies were generated against synthetic peptides derived from the "linker" region, whereas the anti-Mdr1 antibody was raised against a fusion protein containing the amino terminus of Mdr1. Western blot analysis showed that the three antibodies could discriminate between the three isoforms in membrane fractions from Hamster cells transfected with the corresponding full-length or chimeric mdr cDNAs. Immunocytochemistry studies of mdr-transfected cells showed that the three antibodies specifically recognized each P-gp isoform expressed in whole cells. Immunoblotting of normal mouse tissues revealed that the Mdr2 isoform was expressed at very high levels in liver canalicular membrane vesicles (CMV) but not in membrane vesicles prepared from the basolateral (sinusoidal) domain (SMV). Mdr3 was detected in intestinal brush border membrane vesicles and also in CMV, although at levels much lower than Mdr2. Mdr1 was not detected in CMV or SMV but was detected in endometrial tissue from the gravid uterus. Photolabeling experiments with [125I]iodoarylazidoprazosin followed by immunoprecipitation with isoform-specific antibodies indicated that, in CMV, Mdr3 but not Mdr2 could bind the drug analogue. 相似文献
998.
A randomly connected network is constructed with similar characteristics (e.g., the ratio of excitatory and inhibitory neurons, the connection probability between neurons, and the axonal conduction delays) as that in the mammalian neocortex and the effects of high-frequency electrical field on the response of the network to a subthreshold low-frequency electrical field are studied in detail. It is found that both the amplitude and frequency of the high-frequency electrical field can modulate the response of the network to the low-frequency electric field. Moreover, vibrational resonance (VR) phenomenon induced by the two types of electrical fields can also be influenced by the network parameters, such as the neuron population, the connection probability between neurons and the synaptic strength. It is interesting that VR is found to be related with the ratio of excitatory neurons that are under high-frequency electrical stimuli. In summary, it is suggested that the interaction of excitatory and inhibitory currents is also an important factor that can influence the performance of VR in neural networks. 相似文献
999.
Considerable progress has been made in understanding the influence of physical and genetic factors on the patterns of cell division in various model systems. However, how each of these factors directs changes in subcellular structures has remained unclear. Generic machineries for the execution of cell expansion and division have been characterized, but how these are influenced by genetic regulators and physical cell properties remains an open question. To a large degree, the complexity of growing post‐embryonic tissues and a lack of precise predictability have prevented the extraction of rigid correlations between subcellular structures and future orientation of cell division. The Arabidopsis embryo offers an exquisitely predictable and simple model for studying such correlations, but so far the tools and methodology for studying subcellular structures in the early embryo have been lacking. Here, we describe a set of markers to visualize a range of subcellular structures in the early Arabidopsis embryo. We have designed a series of fluorescent cellular reporters optimized for embryos, and demonstrate the effectiveness of using these ‘ACE’ reporters with simple three‐dimensional imaging procedures that preserve delicate cellular structures. We describe the ontogeny of subcellular structures in the early embryo and find that central/peripheral cell polarity is established much earlier than suspected. In addition, we show that the actin and microtubule cytoskeleton has distinct topologies in the embryo. These tools and methods will allow detailed analysis of the events of cellular reorganization that underlie morphogenesis in the Arabidopsis embryo. 相似文献
1000.
Application of protoplast technology to CRISPR/Cas9 mutagenesis: from single‐cell mutation detection to mutant plant regeneration 下载免费PDF全文
Choun‐Sea Lin Chen‐Tran Hsu Ling‐Hung Yang Lan‐Ying Lee Jin‐Yuan Fu Qiao‐Wei Cheng Fu‐Hui Wu Han C.‐W. Hsiao Yesheng Zhang Ru Zhang Wan‐Jung Chang Chen‐Ting Yu Wen Wang Li‐Jen Liao Stanton B. Gelvin Ming‐Che Shih 《Plant biotechnology journal》2018,16(7):1295-1310
Plant protoplasts are useful for assessing the efficiency of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR‐associated protein 9 (Cas9) mutagenesis. We improved the process of protoplast isolation and transfection of several plant species. We also developed a method to isolate and regenerate single mutagenized Nicotianna tabacum protoplasts into mature plants. Following transfection of protoplasts with constructs encoding Cas9 and sgRNAs, target gene DNA could be amplified for further analysis to determine mutagenesis efficiency. We investigated N. tabacum protoplasts and derived regenerated plants for targeted mutagenesis of the phytoene desaturase (NtPDS) gene. Genotyping of albino regenerants indicated that all four NtPDS alleles were mutated in amphidiploid tobacco, and no Cas9 DNA could be detected in most regenerated plants. 相似文献