全文获取类型
收费全文 | 105753篇 |
免费 | 9731篇 |
国内免费 | 210篇 |
专业分类
耳鼻咽喉 | 1480篇 |
儿科学 | 2914篇 |
妇产科学 | 2288篇 |
基础医学 | 14805篇 |
口腔科学 | 2367篇 |
临床医学 | 12869篇 |
内科学 | 19144篇 |
皮肤病学 | 1629篇 |
神经病学 | 8725篇 |
特种医学 | 3615篇 |
外国民族医学 | 10篇 |
外科学 | 15450篇 |
综合类 | 1842篇 |
一般理论 | 116篇 |
预防医学 | 11157篇 |
眼科学 | 2431篇 |
药学 | 8262篇 |
1篇 | |
中国医学 | 97篇 |
肿瘤学 | 6492篇 |
出版年
2022年 | 959篇 |
2021年 | 2098篇 |
2020年 | 1226篇 |
2019年 | 1956篇 |
2018年 | 2308篇 |
2017年 | 1659篇 |
2016年 | 1799篇 |
2015年 | 2033篇 |
2014年 | 2827篇 |
2013年 | 3897篇 |
2012年 | 5640篇 |
2011年 | 5943篇 |
2010年 | 3123篇 |
2009年 | 2957篇 |
2008年 | 4830篇 |
2007年 | 5105篇 |
2006年 | 4819篇 |
2005年 | 4795篇 |
2004年 | 4349篇 |
2003年 | 3998篇 |
2002年 | 3761篇 |
2001年 | 2823篇 |
2000年 | 2898篇 |
1999年 | 2564篇 |
1998年 | 1164篇 |
1997年 | 942篇 |
1996年 | 902篇 |
1995年 | 802篇 |
1994年 | 834篇 |
1993年 | 756篇 |
1992年 | 2109篇 |
1991年 | 2033篇 |
1990年 | 1902篇 |
1989年 | 1873篇 |
1988年 | 1779篇 |
1987年 | 1781篇 |
1986年 | 1691篇 |
1985年 | 1676篇 |
1984年 | 1395篇 |
1983年 | 1267篇 |
1982年 | 845篇 |
1981年 | 720篇 |
1979年 | 1221篇 |
1978年 | 876篇 |
1977年 | 761篇 |
1976年 | 717篇 |
1975年 | 715篇 |
1974年 | 861篇 |
1973年 | 753篇 |
1972年 | 734篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Leonard A. Jason PhD Steven B. Pokorny PhD Monica Adams MPH Annie Topliff MA Courtney Harris BA Yvonne Hunt PhD 《The American journal on addictions / American Academy of Psychiatrists in Alcoholism and Addictions》2009,18(5):367-374
This study evaluated the effects of tobacco Purchase, Use and Possession (PUP) laws on student perceptions of adolescent tobacco use within towns and schools. Twenty‐four towns were randomly assigned into two conditions, the experimental condition (E PUP) involved efforts to increase both PUP law enforcement and reduce minors' access to commercial sources of tobacco, whereas the control condition (C) focused only on efforts to reduce minors' access to commercial sources of tobacco. A hierarchical linear modeling analytical approach was selected due to the multilevel data and nested design. The present study found that over time, youth in the experimental PUP condition observed less youth tobacco usage at school and in their town, and perceived lower rates of tobacco among their peers at school and among friends than youth in the control condition. The findings suggest that PUP law enforcement might be used to strengthen community norms against youth tobacco use. 相似文献
53.
Joanne Dollard Jacquie Smith David R Thompson Simon Stewart 《European Journal of Cardiovascular Nursing》2004,3(1):27-42
BACKGROUND: Cardiac rehabilitation (CR) has an evidence base but traditional models may not readily apply to people living in rural and remote regions. AIM:: To outline published comprehensive and non-hospital based CR models used for people discharged from hospital after a cardiac event that have potential relevance to those living in rural and remote areas in Australia. METHODS: The PubMed database was searched using Medical subject headings (MeSH) terms and the key word 'cardiac rehabilitation' limited to clinical trials. Articles were retrieved if they included at least two components of CR and were not based in an outpatient setting. RESULTS: No CR models specifically developed for rural and remote areas were identified. However, 14 studies were found that outlined 11 non-conventional comprehensive CR models. All provided CR in a home-based setting. Health professionals provided support via telephone contact or home visits, and via resources such as the Heart Manual. Reported outcomes from these CR programs varied: ranging from an increase in knowledge of risk factors, to improvements in physical activity, decreased risk factor profile, improved psychological and social functioning and reductions in health service costs and mortality. CONCLUSION: Home-based, CR models have the most substantive evidence base and, therefore the greatest potential to be developed and made accessible to eligible people living in rural and remote areas. 相似文献
54.
A A Gianelly J B Smith J R Bednar V S Dietz 《American journal of orthodontics and dentofacial orthopedics》1986,90(4):335-341
In a vertically slotted 0.022 X 0.028 inch edgewise system, the use of a two-dimensional ribbon arch--0.022 X 0.016 inch from lateral incisor to lateral incisor and 0.016 X 0.022 inch from the canine to the molars--plus an uprighting spring on the canine maintained incisor position while unilaterally protracting a molar-premolar unit by means of sliding mechanics. Five degrees of labial crown torque was placed in the incisor portion of the wire and the uprighting spring exerted a force of 200 to 250 g. The intra-arch force applied to protract the molar--premolar unit was 300 to 350 g. 相似文献
55.
Superficial bladder cancer: intravesical chemotherapy and tumour progression to muscle invasion or metastases 总被引:2,自引:0,他引:2
G Smith R A Elton G D Chisholm J E Newsam T B Hargreave 《British journal of urology》1986,58(6):659-663
Of 299 patients who presented with superficial bladder cancer (Ta, T1), 60 were treated by intravesical chemotherapy (Epodyl, methotrexate or mitomycin C). The rate of tumour progression to muscle invasion or metastases was identical for each intravesical regime. There was no evidence that mitomycin C promoted tumour progression. Carcinoma in situ in non-tumour-bearing urothelium was the most significant predictive factor for progression to muscle invasion or metastases. 相似文献
56.
Birgit T Priest Kenneth M Blumenthal Jaime J Smith Vivien A Warren McHardy M Smith 《Toxicon》2007,49(2):194-201
The tarantula venom peptides ProTx-I and ProTx-II inhibit voltage-gated sodium channels by shifting their voltage dependence of activation to a more positive potential, thus acting by a mechanism similar to that of potassium channel gating modifiers such as hanatoxin and VSTX1. ProTx-I and ProTx-II inhibit all sodium channel (Nav1) subtypes tested with similar potency and represent the first potent peptidyl inhibitors of TTX-resistant sodium channels. Like gating modifiers of potassium channels, ProTx-I and ProTx-II conform to the inhibitory cystine knot motif, and ProTx-II was demonstrated to bind to sodium channels in the closed state. Both toxins have been synthesized chemically, and ProTx-II, produced by recombinant means, has been used to map the interaction surface of the peptide with the Nav1.5 channel. In comparison, beta-scorpion toxins activate sodium channels by shifting the voltage dependence of activation to more negative potentials, and together these peptides represent valuable tools for exploring the gating mechanism of sodium channels. 相似文献
57.
To evaluate use of a digital photostimulable phosphor imaging system in the neonatal nursery, 150 newborns were divided into three groups of 50. In the first two groups, screen-film and computed radiographs of the chest were obtained at the same radiation exposure; in the third group, computed radiographs were obtained with a 50% dose reduction (half-exposure computed radiographs). All images were blindly evaluated by three readers who scored the quality of visualization of the mediastinum, lung, bone, soft tissues, and endotracheal and nasogastric tubes, and also image density. No statistical differences in visualization of tubes existed among the three groups. Visualization of the mediastinum, lung, bones, and soft tissues was statistically significantly better on computed radiographs than on half-exposure computed radiographs; visualization of the lungs, bones, and soft tissues was statistically significantly better on screen-film radiographs than half-exposure computed radiographs. Image density was statistically better on computed and half-exposure computed radiographs than on screen-film radiographs. 相似文献
58.
59.
Injections of the retrograde fluorescent tracer fast blue in the striatum (STR) and nuclear yellow in the internal segment of the globus pallidus (GPi) in the squirrel monkey (Saimiri sciureus) revealed a nigropallidal projection whose cellular origin was largely distinct from that of the nigrostriatal pathway. Neurons containing the tracer injected in GPi were scattered throughout the substantia nigra-ventral tegmental area complex where they formed approximately 20-25% of the total number of retrogradely labeled cells. Only about 5-10% of all positive neurons were double-labeled after STR-GPi injections. In experiments combining the use of the fluorescent tracer propidium iodide with immunofluorescence, the majority of neurons projecting to GPi displayed tyrosine hydroxylase immunoreactivity. Hence, in addition to their important role at striatal level, midbrain dopaminergic neurons may influence directly the output neurons of the basal ganglia at pallidal level in primates. 相似文献
60.
Dissociation of GFAP intermediate filaments in EAE: observations in the lumbar spinal cord 总被引:1,自引:0,他引:1
Acute experimental allergic encephalomyelitis (EAE) in the Lewis rat is a cell-mediated autoimmune disease of central nervous system myelin. The lesion has been characterized by breakdown of the blood-brain barrier, edema, and periventricular infiltration of macrophages and lymphocytes. At the early stage of the disease, the astrocytes show a marked increase in immunostaining for glial fibrillary acidic protein (GFAP). A corresponding increase in GFAP content, however, cannot be demonstrated. Electron microscopic examination of the early lesion shows a typical reactive astrocytic response expressed by an enlarged watery cytoplasm, particularly at the level of the processes surrounding neurons and blood vessels and in the neuropil itself. The astroglial processes contain numerous glycogen particles (aggregates and single particles). Glial filaments are also conspicuous and are arranged in small bundles or loose thin filaments adjacent to the bundles. The glial filaments that normally appear as tight bundles have expanded and appear less dense. We suggest that the increase in GFAP immunostaining of the astrocytes in the early lesion is due in part to edema, which causes dissociation of the filaments and thereby exposes more antigenic sites to the antibodies. 相似文献