全文获取类型
收费全文 | 5543篇 |
免费 | 369篇 |
国内免费 | 43篇 |
专业分类
耳鼻咽喉 | 172篇 |
儿科学 | 126篇 |
妇产科学 | 28篇 |
基础医学 | 737篇 |
口腔科学 | 81篇 |
临床医学 | 497篇 |
内科学 | 1203篇 |
皮肤病学 | 208篇 |
神经病学 | 653篇 |
特种医学 | 347篇 |
外科学 | 969篇 |
综合类 | 24篇 |
一般理论 | 4篇 |
预防医学 | 193篇 |
眼科学 | 65篇 |
药学 | 290篇 |
中国医学 | 8篇 |
肿瘤学 | 350篇 |
出版年
2023年 | 36篇 |
2022年 | 59篇 |
2021年 | 128篇 |
2020年 | 77篇 |
2019年 | 121篇 |
2018年 | 139篇 |
2017年 | 109篇 |
2016年 | 142篇 |
2015年 | 192篇 |
2014年 | 194篇 |
2013年 | 291篇 |
2012年 | 442篇 |
2011年 | 438篇 |
2010年 | 276篇 |
2009年 | 234篇 |
2008年 | 387篇 |
2007年 | 427篇 |
2006年 | 362篇 |
2005年 | 332篇 |
2004年 | 327篇 |
2003年 | 283篇 |
2002年 | 277篇 |
2001年 | 66篇 |
2000年 | 60篇 |
1999年 | 65篇 |
1998年 | 47篇 |
1997年 | 52篇 |
1996年 | 26篇 |
1995年 | 27篇 |
1994年 | 27篇 |
1993年 | 33篇 |
1992年 | 20篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 12篇 |
1988年 | 17篇 |
1987年 | 17篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 18篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1977年 | 10篇 |
1976年 | 12篇 |
1975年 | 8篇 |
1972年 | 4篇 |
1960年 | 4篇 |
排序方式: 共有5955条查询结果,搜索用时 15 毫秒
31.
The effects of imidacloprid (Advantage) on sheep keds (Melophagus ovinus Linné 1758) were studied in vivo and in vitro by means of direct observation (monitored on video tape) and by light and electron
microscopy. It was found that:
1. Imidacloprid acted rapidly on all motile stages of the sheep keds. Within 3–4 min after exposure they became immobile and
their legs and the abdomen started tetanic trembling movements for 15–30 min, leading to death.
2. The compound is apparently taken up by the body, since it also acted on those sheep keds that had been exclusively exposed
to imidacloprid-contaminated filter papers.
3. The compound is available and active for more than 1 month in the wool of sheep; even rainfall does not reduce its efficacy.
Body contact between treated mother sheep and their lambs protects them from infestation with these ectoparasites.
4. The compound initiates an ultimately lethal destruction of the ganglia, nerve chords and related muscle fibers, as can
be seen in electron micrographs.
Received: 7 October 2000 / Accepted: 18 October 2000 相似文献
32.
Lena Möbus Elke Rodriguez Inken Harder Agatha Schwarz Ulrike Wehkamp Dora Stölzl Nicole Boraczynski Sascha Gerdes Thomas Litman Andreas Kleinheinz Susanne Abraham Annice Heratizadeh Christiane Handrick Eva Haufe Jochen Schmitt Thomas Werfel Stephan Weidinger 《The Journal of allergy and clinical immunology》2021,147(5):1959-1965.e2
33.
34.
Uwe-Martin Zurmöhle Jochen Herms Reimar Schlingensiepen Karl-Hermann Schlingensiepen Wolfgang Brysch 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1994,99(1):17-24
Synapsin I is a synaptic phosphoprotein that is involved in the short-term regulation of neurotransmitter release. In this report we present the first extensive study of the developmental expression of its corresponding messenger ribonucleic acid (mRNA) by in situ hybridization and northern blot analysis in rat brain. Synapsin I mRNA showed pronounced differences in expression in different brain regions during postnatal development. The early expression of synapsin I mRNA in ontogenetically older regions such as the thalamus, the piriform cortex and the hippocampus coincides with the earlier maturation of these regions, in contrast to its later expression in ontogenetically younger areas such as the cerebellum and the neocortex. An intriguing expression pattern was found in the hippocampus. In all hippocampal subregions synapsin I mRNA expression increased from postnatal day (PND) 1 to 17. After PND 17, however, there was a marked dissociation between persisting high expression levels in CA3 and the dentate gyrus and a strong decline in synapsin I mRNA expression in CA1. The persistence of synapsin I in some adult rat brain regions indicates that it plays a part in synapse formation during plastic adaption in neuronal connectivities. 相似文献
35.
Olga Tymofiyeva Peter Proff Ernst-Jürgen Richter Peter Jakob Jochen Fanghnel Tomas Gedrange Kurt Rottner 《Annals of anatomy》2007,189(4):356-361
There is a series of tools useful for gathering diagnostic information on patients with temporomandibular joint disorders. Tracings of the joint movement (axiography) provide useful information about the motion of the joints. Since the availability of electronic axiographic tracers, the movement of the condyles can be resolved with high resolution both in space and in time. In order to obtain information about the anatomical relation of the joint surfaces and the disc, magnetic resonance tomography imaging (MRI) is routinely carried out. It is common practice to take MR images of the joints with the mouth closed and fully open. In order to correlate the MR images with the axiographic tracings, a series of images can provide much more information. In this study we examined patients with distinct temporomandibular joint (TMJ) clicks. In one case, the click occurs once a day, while in the other case the click happens every time the mouth is opened. In order to obtain information about both motion and anatomical relation of the TMJ at and around the position where the clicks occur, we recorded a series of MRI scans with the mouth gradually opened and before and after joint clicks. Real-time axiographic tracings during the click were taken with an optimized system where the polar moments were reduced as much as possible to follow the movement during the click. These tracings were correlated with the MRI scans to determine the exact internal conditions of the TMJ and the changes during the click. In particular cases, the additional information provided by this procedure can be useful in deciding whether and which therapeutic intervention is advisable. 相似文献
36.
Reiss J Bonin M Schwegler H Sass JO Garattini E Wagner S Lee HJ Engel W Riess O Schwarz G 《Molecular genetics and metabolism》2005,85(1):12-20
Molybdenum cofactor (Moco)-deficiency is a lethal autosomal recessive disease, for which until now no effective therapy is available. The biochemical hallmark of this disorder is the inactivity of the Moco-dependent sulfite oxidase, which results in elevated sulfite and diminished sulfate levels throughout the organism. In humans, Moco-deficiency results in neurological damage, which is apparent in untreatable seizures and various brain dysmorphisms. We have recently described a murine model for Moco-deficiency, which reflects all enzyme and metabolite changes observed in the patients, and an efficient therapy using a biosynthetic precursor of Moco has been established in this animal model. We now analyzed these mice in detail and excluded morphological brain damage, while expression analysis with microarrays indicates a massive cell death program. This neuronal damage appears to be triggered by elevated sulfite levels and is ameliorated in affected embryos by maternal clearance. 相似文献
37.
Wellinghausen N Sing A Kern WV Perner S Marre R Rentschler J 《International journal of medical microbiology : IJMM》2002,292(1):59-63
A 77-year-old farmer developed cough with sputum production, fever, bloody nasal discharge and a mass in his right maxillary sinus leading to necrotic ulceration of the sinus. Corynebacterium ulcerans, carrying the beta-phage for the diphtheria toxin and secreting the toxin, was detected microscopically and by culture from the sinusoidal and ulcer discharge. Despite immediate antimicrobial chemotherapy the patient died of pulmonary failure associated with the production of large amounts of very viscous sputum. Identification of the causative agent, pathophysiological aspects and risk factors of this unusal infection are discussed. 相似文献
38.
Fischbach C Seufert J Staiger H Hacker M Neubauer M Göpferich A Blunk T 《Tissue engineering》2004,10(1-2):215-229
In vivo and in vitro studies have demonstrated both promise and current limitations in tissue engineering of fat. Herein, we report the establishment of a well-defined three-dimensional (3-D) in vitro model useful for systematic investigations of 3-D adipogenesis. Polyglycolic acid fiber meshes were dynamically seeded with 3T3-L1 preadipocytes; subsequently, cell-polymer constructs were hormonally induced and cultivation under three different conditions was evaluated. Regarding tissue coherence and intracellular lipid content, culture of cell-polymer constructs either dynamically in well plates or in stirred bioreactors yielded similar results, which were distinctly improved compared with static conditions in well plates. At the protein and mRNA levels, significantly increased expression of genes characteristic for a mature adipose phenotype was demonstrated for constructs dynamically cultured in well plates, as compared with static conditions. Furthermore, investigation of lipolysis under stimulating and inhibiting conditions demonstrated functionality of the dynamically differentiated constructs. Using dynamic culture conditions, the presented in vitro model system is suggested as a valuable tool serving both fat tissue engineering and basic research by facilitating investigations of tissue-inherent features not possible under conventional 2-D culture conditions. 相似文献
39.
Ontogeny, differentiation and growth of the endocrine pancreas 总被引:7,自引:0,他引:7
Peters J Jürgensen A Klöppel G 《Virchows Archiv : an international journal of pathology》2000,436(6):527-538
The pancreas develops from the primitive foregut endoderm, which differentiates into ductal, acinar and endocrine cells. This
complex process is probably replicated in the adult pancreas when endocrine cell renewal is required, as may be the case in
diabetes mellitus. This review describes what is known about the morphogenesis of the endocrine pancreas during ontogeny and
the mechanisms regulating its differentiation and growth.
Received: 23 December 1999 / Accepted: 15 February 2000 相似文献
40.
Moraxella catarrhalis--infected alveolar epithelium induced monocyte recruitment and oxidative burst 总被引:1,自引:0,他引:1
Rosseau S Wiechmann K Moderer S Selhorst J Mayer K Krüll M Hocke A Slevogt H Seeger W Suttorp N Seybold J Lohmeyer J 《American journal of respiratory cell and molecular biology》2005,32(2):157-166
The recruitment of monocytes appears to be a crucial factor for inflammatory lung disease. Alveolar epithelial cells contribute to monocyte influx into the lung, but their impact on monocyte inflammatory capacity is not entirely clear. We thus analyzed the modulation of monocyte oxidative burst by A549 and isolated human alveolar epithelial cells. Epithelial infection with Moraxella catarrhalis induced monocyte adhesion, transepithelial migration, and superoxide generation, whereas stimulation with lipopolysaccharide, tumor necrosis factor-alpha, interleukin-1beta, or interferon-gamma induced adhesion or transmigration, but failed to initiate monocyte burst. The effect of microbial challenge was mimicked by phorbol myristate acetate and inhibited by the protein kinase C inhibitor bisindoylmaleimide. Furthermore, evidence for a role of platelet-activating factor-signaling in monocytes is presented. Monocyte burst was neither induced by supernatant nor affected by fixation of A549 cells, excluding the contribution of epithelium-derived soluble factors but emphasizing the mandatory role of intercellular contact. The employment of blocking antibodies, however, denied a role for the adhesion molecules intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, or CD11b/CD18 and CD49d/CD29. In essence, infection of alveolar epithelial cells with M. catarrhalis might amplify the inflammatory capacity of invading monocytes eliciting their superoxide production. The epithelial response to this microbial challenge thus clearly differed from that to proinflammatory cytokines. 相似文献