全文获取类型
收费全文 | 13496篇 |
免费 | 977篇 |
国内免费 | 71篇 |
专业分类
耳鼻咽喉 | 104篇 |
儿科学 | 385篇 |
妇产科学 | 227篇 |
基础医学 | 2247篇 |
口腔科学 | 323篇 |
临床医学 | 1203篇 |
内科学 | 3040篇 |
皮肤病学 | 313篇 |
神经病学 | 1700篇 |
特种医学 | 280篇 |
外科学 | 1307篇 |
综合类 | 60篇 |
一般理论 | 9篇 |
预防医学 | 1026篇 |
眼科学 | 139篇 |
药学 | 1011篇 |
中国医学 | 48篇 |
肿瘤学 | 1122篇 |
出版年
2024年 | 19篇 |
2023年 | 134篇 |
2022年 | 327篇 |
2021年 | 626篇 |
2020年 | 345篇 |
2019年 | 442篇 |
2018年 | 496篇 |
2017年 | 391篇 |
2016年 | 446篇 |
2015年 | 472篇 |
2014年 | 577篇 |
2013年 | 711篇 |
2012年 | 1103篇 |
2011年 | 1170篇 |
2010年 | 656篇 |
2009年 | 537篇 |
2008年 | 846篇 |
2007年 | 883篇 |
2006年 | 767篇 |
2005年 | 750篇 |
2004年 | 718篇 |
2003年 | 592篇 |
2002年 | 560篇 |
2001年 | 94篇 |
2000年 | 76篇 |
1999年 | 83篇 |
1998年 | 111篇 |
1997年 | 106篇 |
1996年 | 69篇 |
1995年 | 71篇 |
1994年 | 50篇 |
1993年 | 38篇 |
1992年 | 38篇 |
1991年 | 31篇 |
1990年 | 33篇 |
1989年 | 14篇 |
1988年 | 17篇 |
1987年 | 8篇 |
1986年 | 19篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Gian Marco Moneta Claudia Bracaglia Ivan Caiello Chiara Farroni Denise Pires Marafon Raffella Carlomagno Linda Hiraki Marina Vivarelli Alessandra Gianviti Simone Carbogno Walter Ferlin Cristina de Min Earl Silverman Rita Carsetti Fabrizio De Benedetti Emiliano Marasco 《European journal of immunology》2023,53(7):2250319
92.
Chlorhexidine susceptibility and Eagle effect in planktonic cells and biofilm of nosocomial isolates
Marchi Ana Paula Farrel Côrtes Marina Vásconez Noguera Saidy Rossi Flavia Levin Anna Sara Figueiredo Costa Silvia Perdigão Neto Lauro Vieira 《European journal of clinical microbiology & infectious diseases》2023,42(6):787-792
European Journal of Clinical Microbiology & Infectious Diseases - The aim of this study is to evaluate the chlorhexidine gluconate (CHG) susceptibility in both planktonic cells and biofilm of... 相似文献
93.
Biasi Giovanni; Panozzo Marina; Pertile Paolo; Mezzalira Silvio; Facchinetti Antonella 《International immunology》1994,6(7):983-989
We observed that peripheral T cells activated in vivo or invitro by superantigens are susceptible to cell death when theirantigen receptor is cross-linked with the appropriate anti-ßTCR mAb. TCR ligation by mAbs specifically drove the T cellclonal deletion in both CD4+ and CD8+ cell subsets. An IL-2/1L-2Rinteraction seems to be a critical step In predisposing superantigenactivated cells to death; In fact, in vivo IL-2R bockade reversedT cell deletion In superantlgen plus anti-ß TCR mAbtreated mice. TCR ligatlon by mAbs also produced cell deathof the relevant targets in in vitro IL-2 activated T cells.Surprisingly, no T cell deletion was demonstrable in IL-2 activatedcells following staphylococcal enterotoxin B - TCR Interaction,ruling out the possibility that superantigen in Itself can inducecell death. Thus, while superantigen activation opens the celldeath program, a subsequent TCR-antigen (self) Interaction appearsnecessary to produce clonal deletion in mature T lymphocytes. 相似文献
94.
95.
Caterina Mariotti Graziella Uziel Franco Carrara Marina Mora Alessandro Prelle Valeria Tiranti Stefano DiDonato Massimo Zeviani 《Journal of neurology》1995,242(9):547-556
A male infant, born from consanguineous parents, suffered from birth with a progressive neuromuscular disorder characterized by psychomotor delay, hypotonia, muscle weakness and wasting, deep-tendon areflexia and spastic posture. High levels of lactic acid in blood and cerebrospinal fluid suggested a mitochondrial respiratory chain defect. Muscle biopsy revealed raggedred and cytochromec oxidase-negative fibres, lipid accumulation and dystrophic changes. Multiple defects of respiratory complexes were detected in muscle homogenate, but cultured fibroblasts, myoblasts and myotubes were normal. Southern blot analysis showed markedly reduced levels of mitochondrial DNA (mtDNA) in muscle, while lymphocytes, fibroblasts and muscle precursor cells were normal. Neither depletion of mtDNA nor abnormalities of the respiratory complexes were observed in innervated muscle fibres cultured for as long as 4 months. No mutations were observed in two candidate nuclear genes,mtTFA andmtSSB, retro-transcribed, amplified and sequenced from the proband's mRNA. Sequence analysis of the mtDNA D-loop and of the origin of replication of the mtDNA light strand failed to identify potentially pathogenic mutations of these replicative elements in the proband's muscle mtDNA. Our findings indicate that mtDNA depletion is due to a nuclear encoded gene and suggest that the abnormality underlying defective mtDNA propagation must occur after muscle differentiation in vivo. 相似文献
96.
The inheritance of focal dystonias was investigated in 43 families containing 43 index cases with torticollis (n = 21), blepharospasm (n = 18) and writer's cramp (n = 4). They generated a potential population of 235 first-degree relatives, and 168 out of 179 living first-degree relatives were examined. Ten relatives with dystonia were identified in ten families. Another two parents from two of the same group of ten families were affected according to the family history. The majority of the secondary cases (six patients, five siblings, and one child) were not aware of any dystonia. The tendency for affected relatives to have the same type of dystonia as index patients was observed only for torticollis. Overall, 23% of index patients had relatives with dystonia. Segregation analysis suggested the presence of an autosomal dominant gene or genes with reduced penetrante underlying focal dystonia. 相似文献
97.
Testicular peritubular cells are located in the lamina propria of seminiferous tubules. These cells, significantly contributing to the basal membrane of seminiferous epithelium, have been studied in a number of species. However, there is a lack of data on the development of the lamina propria in the human testis. The aim of our survey was to investigate the characteristics of the lamina propria and, in particular, peritubular cells in the fetal human testes by immunohistological and stereological methods. Therefore, testes (14–39 weeks of gestation, n=45) were dissected and fixed in a 4% buffered paraformaldehyde solution. Several pieces of each testis were embedded in paraffin and processed for immunohistochemical and stereological analysis. All investigated testes have shown sex cords in the process of development and differentiation. Morphologically, peritubular cells in the lamina propria can be divided into two types: fibroblast-like (FL) and myoid-like (ML) type (cells which much resemble mature myoid cells). By immunohistochemistry, both FL and ML cells are found to be strongly positive for the intermediate filament desmin, but negative for -smooth actin. While FL cells intensively express Ki-67 demonstrating proliferative activity, ML cells are found to be negative. The basement membrane of sex cords as well as the blood vessels of the interstitium show strong positivity to collagen IV and laminin. Concerning the correlation between the appearance of the investigated antigens with the gestational age, all antigens have been expressed (in the manner described above) already in the 14th week of gestation. The stereological analysis of the number (Nv) and volume (Vv) of peritubular cells indicates a pulsatile development of these cells in the lamina propria of the human fetal testis. While the stereological variables determined for FL cells show a gradual decrease, the same variables determined for ML cells demonstrate a successive increase. It appears that the lamina propria of the fetal human testes shares many of the properties previously discovered in rodents. 相似文献
98.
Marina Ripamonti Laura Capolongo Giulia Melegaro Carlo Gornati Alberto Bargiotti Michele Caruso Maria Grandi Antonino Suarato 《Investigational new drugs》1996,14(2):139-146
Summary The relationship between different chemical modifications on morpholinylanthracyclines and their ability to overcome multidrug resistance (MDR) has been evaluated testing all compounds in vitro on LoVo and LoVo/DX human colon adenocarcinoma cells and in vivo on disseminated P388 and P388/DX murine leukemias.Results obtained led us to the following conclusions: 1) the insertion of the morpholinyl or the methoxymorpholinyl group on position 3 of the sugar moiety confers the ability to overcome MDR in vitro and in vivo; conversely, 4 morpholinyl compounds are effective on MDR cells only in vitro and result inactive in vivo on DX-resistant leukemia; 2) all chemical modifications performed on 3 morpholinyl or methoxymorpholinyl derivatives, that is substitutions on the aglycone or on position 2 of the morpholino ring, do not interfere with the activity of the compounds: all derivatives present in fact the same efficacy on sensitive and resistant models.It is concluded that position 3 in the sugar moiety plays a crucial role in the ability of morpholinylanthracyclines to overcome MDR. 相似文献
99.
Neuronal Clones in the Cerebral Cortex Show Morphological and Neurotransmitter Heterogeneity during Development 总被引:3,自引:3,他引:0
Lavdas Alexandros A.; Mione Marina C.; Parnavelas John G. 《Cerebral cortex (New York, N.Y. : 1991)》1996,6(3):490-497
The mammalian cerebral cortex, although a structure of greatcomplexity, is characterized by a high degree of organizationwhere the proportions, spatial relationships, and propertiesof the various cell types are rigidly controlled. The mechanismsresponsible for the creation of such a rigid distribution ofcell types are not known. Lineage studies in adult rats havesuggested that each of the cortical progenitor cells liningthe telencephalic ventricles during embryonic development givesrise to progeny of the same phenotype (homogeneous clones).However, the possibility that homogeneous clones are the resultof complex processes affecting both the final number and thephenotype of clonally related cells during development has notbeen investigated. In the present study, we followed the developmentof cortical cell lineages labeled with retroviral injectionsat embryonic day (E) 16 in rats of 7, 14, or 21 d of age usingelectron microscopy and immunocytochemistry for the neurotransmittersglutamate and GABA. We found that a significant number of corticalclones at postnatal day (P) 7 and P14, and fewer at P21, showedmixed pyramidal/nonpyramidal cell composition. We sometimesobserved that "mixed" neuronal clones contained cells immunoreactivefor both glutamate and GABA. In the general population of corticalcells, "bireactive" neurons represented 3.7% of all neuronsat P7, 1.8% at P14, and 0.6% in adult rats. Although the changein the composition of neuronal clones between the third weekof postnatal life and adulthood may be due to changes in thephenotype of some developing neurons, we would like to suggestthat it is probably due to selective neuronal cell death. 相似文献
100.
Nicotine induces glutamate release from thalamocortical terminals in prefrontal cortex. 总被引:6,自引:0,他引:6
It has been proposed that activation of nicotinic acetylcholine receptors (nAChRs) can activate the prefrontal cortex, enhancing attention and cognition. Nicotine can stimulate the release of several different neurotransmitters in many brain regions. In the present study, we found that stimulation of nAChRs by nicotine or the endogenous agonist, acetylcholine (ACh), induces a large spontaneous increase in glutamate release onto layer V pyramidal neurons of the prefrontal cortex. This release of glutamate, measured by spontaneous excitatory postsynaptic currents (sEPSCs) in the prefrontal cortical slice, depends on intact thalamocortical terminals. It can be suppressed by mu-opioids or eliminated by blocking action potentials. The increase in sEPSCs is sensitive to low concentrations of nicotine, suggesting the involvement of high-affinity (eg alpha(4)beta(2)) nAChRs. Recent work has shown alterations in prefrontal alpha(4)beta(2) nAChRs in autism and schizophrenia, two conditions that are distinguished by abnormal prefrontal cortical activation as well as difficulty in certain aspects of cognition and integrating social and emotional cues. We show that mice lacking the beta(2) nAChR subunit do not show increased sEPSCs with either nicotine or ACh, again implicating high-affinity nicotinic receptors. These findings give new insight into the mechanism by which nicotine affects excitatory neurotransmission to the output neurons of the cerebral cortex in a pathway that is critical for cognitive function and reward expectation. 相似文献