全文获取类型
收费全文 | 15757篇 |
免费 | 1233篇 |
国内免费 | 8篇 |
专业分类
16998篇 |
出版年
2024年 | 24篇 |
2023年 | 96篇 |
2022年 | 247篇 |
2021年 | 459篇 |
2020年 | 243篇 |
2019年 | 312篇 |
2018年 | 422篇 |
2017年 | 367篇 |
2016年 | 599篇 |
2015年 | 871篇 |
2014年 | 949篇 |
2013年 | 1123篇 |
2012年 | 1440篇 |
2011年 | 1428篇 |
2010年 | 887篇 |
2009年 | 680篇 |
2008年 | 1048篇 |
2007年 | 929篇 |
2006年 | 900篇 |
2005年 | 857篇 |
2004年 | 749篇 |
2003年 | 630篇 |
2002年 | 619篇 |
2001年 | 113篇 |
2000年 | 80篇 |
1999年 | 112篇 |
1998年 | 134篇 |
1997年 | 94篇 |
1996年 | 71篇 |
1995年 | 54篇 |
1994年 | 50篇 |
1993年 | 57篇 |
1992年 | 48篇 |
1991年 | 29篇 |
1990年 | 40篇 |
1989年 | 42篇 |
1988年 | 19篇 |
1987年 | 23篇 |
1986年 | 17篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 11篇 |
1974年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
G P Sgaragli R Ninci L Della Corte R Borghesi M Nardini N Battistini 《Bollettino della Società italiana di biologia sperimentale》1984,60(9):1727-1733
Data obtained in this preliminary study show that in patients chronically treated either with Chlorimipramine (n = 6) or with Chlorpromazine (n = 2), significant amounts of the corresponding Nor1- and Nor2-metabolites were detected in plasma. The role of these metabolites in the overall therapeutic effect is under investigation. 相似文献
12.
H. Sinzinger K. Silberbauer A.K. Horsch Andrea Gall 《Prostaglandins & other lipid mediators》1981,21(1):49-51
During successful treatment of peripheral vascular disease with synthetic prostacyclin no alteration in platelet function was reported (1).In 8 patients infused with synthetic prostacyclin continuously for 7 days intraarterially, the platelet function was monitored. Special attention was drawn to the platelet sensitivity in vitro for PGI2, which is discussed as an important factor maintaining the hemostatic balance.In all the patients with peripheral vascular disease between 24 and 48 hours after the beginning of the infusion a sudden decrease in platelet sensitivity accompanied by an increase in platelet count could be seen.These dramatic alterations representing probably a rebound phenomenon occurring during long-term PGI2-treatment might be an explanation for a non-beneficial effect of the treatment and in some cases a limiting factor for the continuation of the infusion itself. It is not clear, if this rebound phenomenon is due to a stimulation of an endogenous inhibitor, lowering the synthesis of a naturally occurring substance acting against this inhibitor or tachyphylaxia. 相似文献
13.
14.
Maura Marinozzi Andrea Carotti Roccaldo Sardella Federica Buonerba Federica Ianni Benedetto Natalini Daniela Passeri Giovanni Rizzo Roberto Pellicciari 《Bioorganic & medicinal chemistry》2013,21(13):3780-3789
An asymmetric synthetic strategy was designed for the preparation of the four possible diastereoisomers of 3,6-dimethyl-1-(2-methylphenyl)-4-(4-phenoxyphenyl)-4,8-dihydro-1H-pyrazolo[3,4-e][1,4]thiazepin-7-one, a non-steroidal FXR agonist, we recently discovered following a virtual screening approach. The results obtained from an AlphaScreen assay clearly demonstrated that only the isomer endowed with 4R,6S absolute configuration is responsible for the biological activity. A deep investigation of the different putative binding modes adopted by these enantiomerically pure ligands using computational modeling studies confirmed the enantioselectivity of FXR towards this class of molecules. 相似文献
15.
Uric Acid Amplifies Aβ Amyloid Effects Involved in the Cognitive Dysfunction/Dementia: Evidences From an Experimental Model In Vitro 下载免费PDF全文
16.
Andrea E Bialocerkowski Mary Galea 《Journal of brachial plexus and peripheral nerve injury》2006,1(1):1-6
Background
Animal studies have demonstrated complex cortical reorganization following peripheral nerve lesion. Central projection fields of intact nerves supplying skin areas which border denervated skin, extended into the deafferentiated cortical representation area. As a consequence of nerve lesions and subsequent reorganization an increase of the somatosensory evoked potentials (SEPs) was observed in cats when intact neighbouring nerves were stimulated. An increase of SEP-components of patients with nerve lesions may indicate a similar process of posttraumatic plastic cortical reorganization.Methods
To test if a similar process of post-traumatic plastic cortical reorganization does occur in humans, the SEP of intact neighbouring hand nerves were recorded in 29 patients with hand nerve lesions. To hypothetically explain the observed changes of SEP-components, SEP recording following paired stimulation of the median nerve was performed in 12 healthy subjects.Results
Surprisingly 16 of the 29 patients (55.2%) showed a reduction or elimination of N35, P45 and N60. Patients with lesions of two nerves showed more SEP-changes than patients with a single nerve lesion (85.7%; 6/7 nerves; vs. 34.2%; 13/38 nerves; Fisher's exact test, p < 0.05). With paired stimulation a suppression of the amplitude of N20, P25 and P45 (p < 0.05; sign test), and a marked increment of N35 (p < 0.05; sign test) and N60 (not significant; sign test) of the second response could be observed.Conclusion
The results of the present investigation do not provide evidence of collateral innervation of peripherally denervated cortical neurons by neurons of adjacent cortical representation areas. They rather suggest that secondary components of the excitatory response to nerve stimulation are lost in cortical areas, which surround the denervated region. 相似文献17.
Reinvasion of pest animals after incomplete control is a major challenge for invasive species management, yet little is known about the behavioural and demographic categories of reinvaders or the mechanisms that drive population‐level responses to control. To understand the fine‐scale mechanisms of reinvasion, we examined changes in demography, movements and activity patterns of reinvading alien black rats Rattus rattus in the short (4 weeks) and longer term (3 months) following localised experimental pest removal. Using recovery and invasion theory, we tested three hypothesised mechanisms of reinvasion: the ‘in situ effect’, the ‘trickle effect’ and the ‘vacuum effect’. We created space for reinvasion by removing black rats from the core of replicate 1‐ha plots (short‐term experiment) and later by removing animals from the entire plot (longer‐term experiment). Reinvaders were characterised as dispersing juveniles, floaters or neighbours. Radio‐tracking quantified home range changes for adjacent resident animals (short‐term experiment only). In the short term, there was no net influx of rats after targeted removal. Radio‐tracked residents’ movements were highly variable and displayed no directional changes after nearby conspecifics were removed. However, in the longer term, removal led to slow population recovery through a mix of reinvading floaters, dispersing juveniles and shifting residents. These responses best support a hypothesis of reinvasion through a trickle effect, with rats being extremely mobile and having a high degree of population turnover, even in untreated sites. Our findings provide the first test of reinvasion theory at a small scale, demonstrating the importance of understanding the differing categories of reinvaders and mechanisms of reinvasion after population control. These mechanisms drive the rate of population recovery and, in turn, should help determine which strategy of pest control should be used, and the frequency with which they are implemented, in order to slow the recovery of pest populations. 相似文献
18.
Falvo S Di Carli M Desiderio A Benvenuto E Moglia A America T Lanteri S Acquadro A 《Proteomics》2012,12(3):448-460
Plants respond to ultraviolet stress inducing a self-defence through the regulation of specific gene family members. The UV acclimation is the result of biochemical and physiological processes, such as enhancement of the antioxidant enzymatic system and accumulation of UV-absorbing phenolic compounds (e.g. flavonoids). Globe artichoke is an attractive species for studying the protein network involved in UV stress response, being characterized by remarkable levels of inducible antioxidants. Proteomic tools can assist the evaluation of the expression patterns of UV-responsive proteins and we applied the difference in-gel electrophoresis (DIGE) technology for monitoring the globe artichoke proteome variation at four time points following an acute UV-C exposure. A total of 145 UV-C-modulated proteins were observed and 119 were identified by LC-MS/MS using a ~144,000 customized Compositae protein database, which included about 19,000 globe artichoke unigenes. Proteins were Gene Ontology (GO) categorized, visualized on their pathways and their behaviour was discussed. A predicted protein interaction network was produced and highly connected hub-like proteins were highlighted. Most of the proteins differentially modulated were chloroplast located, involved in photosynthesis, sugar metabolisms, protein folding and abiotic stress. The identification of UV-C-responsive proteins may contribute to shed light on the molecular mechanisms underlying plant responses to UV stress. 相似文献
19.
Human Cytomegalovirus UL131-128 Genes Are Indispensable for Virus Growth in Endothelial Cells and Virus Transfer to Leukocytes 下载免费PDF全文
20.
Bastien Polizzi Andrea Fanesi Filipa Lopes Magali Ribot Olivier Bernard 《PLoS computational biology》2022,18(4)
We present a spatial model describing the growth of a photosynthetic microalgae biofilm. In this 2D-model we consider photosynthesis, cell carbon accumulation, extracellular matrix excretion, and mortality. The rate of each of these mechanisms is given by kinetic laws regulated by light, nitrate, oxygen and inorganic carbon. The model is based on mixture theory and the behaviour of each component is defined on one hand by mass conservation, which takes into account biological features of the system, and on the other hand by conservation of momentum, which expresses the physical properties of the components. The model simulates the biofilm structural dynamics following an initial colonization phase. It shows that a 75 μm thick active region drives the biofilm development. We then determine the optimal harvesting period and biofilm height which maximize productivity. Finally, different harvesting patterns are tested and their effect on biofilm structure are discussed. The optimal strategy differs whether the objective is to recover the total biofilm or just the algal biomass. 相似文献