全文获取类型
收费全文 | 12308篇 |
免费 | 881篇 |
国内免费 | 58篇 |
专业分类
耳鼻咽喉 | 148篇 |
儿科学 | 283篇 |
妇产科学 | 144篇 |
基础医学 | 1815篇 |
口腔科学 | 189篇 |
临床医学 | 1093篇 |
内科学 | 2460篇 |
皮肤病学 | 167篇 |
神经病学 | 1323篇 |
特种医学 | 525篇 |
外国民族医学 | 1篇 |
外科学 | 1938篇 |
综合类 | 112篇 |
一般理论 | 4篇 |
预防医学 | 856篇 |
眼科学 | 277篇 |
药学 | 1126篇 |
中国医学 | 44篇 |
肿瘤学 | 742篇 |
出版年
2023年 | 77篇 |
2022年 | 118篇 |
2021年 | 221篇 |
2020年 | 166篇 |
2019年 | 227篇 |
2018年 | 280篇 |
2017年 | 169篇 |
2016年 | 209篇 |
2015年 | 272篇 |
2014年 | 347篇 |
2013年 | 527篇 |
2012年 | 771篇 |
2011年 | 839篇 |
2010年 | 498篇 |
2009年 | 463篇 |
2008年 | 791篇 |
2007年 | 836篇 |
2006年 | 832篇 |
2005年 | 830篇 |
2004年 | 794篇 |
2003年 | 705篇 |
2002年 | 668篇 |
2001年 | 174篇 |
2000年 | 127篇 |
1999年 | 173篇 |
1998年 | 167篇 |
1997年 | 131篇 |
1996年 | 118篇 |
1995年 | 106篇 |
1994年 | 86篇 |
1993年 | 91篇 |
1992年 | 112篇 |
1991年 | 97篇 |
1990年 | 82篇 |
1989年 | 97篇 |
1988年 | 60篇 |
1987年 | 61篇 |
1986年 | 74篇 |
1985年 | 77篇 |
1984年 | 74篇 |
1983年 | 72篇 |
1982年 | 65篇 |
1981年 | 57篇 |
1980年 | 44篇 |
1979年 | 38篇 |
1978年 | 29篇 |
1977年 | 31篇 |
1975年 | 30篇 |
1973年 | 37篇 |
1972年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Rawling Jean M.; Driscoll Eric R.; Poirier Guy G.; Kirkland James B. 《Carcinogenesis》1993,14(12):2513-2516
Poly(ADP-ribose) (polymer) is enzymatically synthesized on nuclearproteins in response to DNA strand breaks. NAD+ is the substratefor this reaction, which is catalyzed by Poly(ADP-ribose)polymerase.This post-translational modification occurs in response to DNAstrand breaks and is thought to play an important role in DNArepair. Polymer synthesis resulting from DNA damage has beendescribed in cultured cells, but measurement is more difficultin animal tissues. In this study, modifications were made toan earlier method to measure carcinogen-induced increases inpolymer levels in vivo. RNase I was added to the enzyme mixtureused to digest polymer to ribosyladenosine (RAdo). This preventedthe inhibition of snake venom phosphodiesterase by RNA. TheHPLC analysis was improved, allowing elimination of the secondboronate affinity chromatography step traditionally used topurify 相似文献
43.
Werner Spileers Guy A. Orban Hugo Maes Luc Missotten 《Documenta ophthalmologica. Advances in ophthalmology》1988,68(3-4):363-374
CMSS-VEPs are presented as a sensitive, non-invasive functional investigation technique of the visual function, applicable in clinical practice. New improvements of the technique are presented. The underlying neuronal mechanisms are discussed. The clinical use is illustrated in a case of optic neuritis. 相似文献
44.
B n dicte Brichard Jacques Ninane Serge Gosseye Christine Verellen-Dumoulin Christiane Vermylen Jean Rodhain Guy Comu 《Pediatric hematology and oncology》1991,8(3):215-219
A 9-year-old boy presented with a small subcutaneous tumor of the trunk and diffuse bone marrow involvement. The first histological diagnosis given was undifferentiated malignancy possibly of neural crest origin and chemotherapy was started immediately using vincristine, cyclophosphamide, cisplatin, and teniposide (OPEC). Complete response was achieved after four courses of chemotherapy. Histological slides were then reviewed and the final diagnosis of alveolar rhabdomyosarcoma (RMS) was retained. Moreover, chromosome analysis of malignant cells in the bone marrow revealed a translocation involving chromosomes 2 and 13:t(2;13) (q35;q14). This specific karyotype finding has been recently reported in a few cases and could be specific for alveolar RMS. The patient had a relapse 7 months after diagnosis and died 4 months later. 相似文献
45.
A. Tchelet T. Vogel D. Helman R. Guy C. Neospouolus V. Goffin J. Djiane A. Gertler 《Molecular and cellular endocrinology》1997,130(1-2):141-152
A new analogue of recombinant human growth hormone (hGH), hGH des(1–6,14) was expressed in Escherichia coli, refolded and purified to homogeneity. The mutation decreased the hormone's ability to bind lactogenic and somatogenic receptors through its site 1, and almost completely abolished its ability to bind these receptors through site 2, as evidenced by both binding and gel-filtration experiments. More specifically, the binding to prolactin receptors (PRLRs) from various species or their soluble recombinant extracellular domains (ECDs) was decreased 1.5–4-fold, whereas the binding to hGH receptor (hGHR) was decreased 10–85-fold. These changes caused an almost total loss of hormone agonistic activity in several in vitro bioassays and subsequently, the hGH des(1–6,14) analogue acquired antagonistic properties. This antagonistic activity was dependent upon modification of site 1. In those cases in which the binding was reduced only slightly, e.g. binding to rabbit PRLRs, hGH des(1–6,14) acted as a strong antagonist, whereas in others in which the binding of site 1 was reduced to a higher degree, such as other PRLRs and, in particular, hGHR, the antagonistic activity was correspondingly weaker. Circular dichroism spectra of the analogue suggested that these changes do not result from a decrease in overall -helix content, but rather from minor local structural modifications at the N-terminus. 相似文献
46.
Implementation of a successful endovascular surgical program in a non-teaching tertiary-care centre in Ontario. 总被引:1,自引:0,他引:1
Rod P N Willoughby John A Fenton Santosh R Pudupakkam Robert A Greco Evan W D Roberts Guy DeRose Stewart Kribs 《Canadian journal of surgery》2004,47(3):182-188
Endovascular surgical techniques have become an accepted standard of care for high-risk patients with abdominal aortic aneurysms and for certain patients with thoracic aortic pathology and peripheral arterial aneurysms. In Canada, endovascular surgery has been concentrated in tertiary-care academic teaching institutions. As the technology evolves and as expertise advances, the applicability of endovascular techniques will expand. With time, and as the demand for endovascular techniques rises, this expertise will increasingly need to be delivered by dedicated vascular surgical services in nonteaching institutions. The dissemination of endovascular surgical capabilities represent a unique challenge. We report the successful implementation of an endovascular surgical program in a tertiary-care nonteaching institution using a carefully planned preceptorship model. We review our initial 49 cases and discuss 6 factors important to the successful establishment of an endovascular surgical service: education, teamwork, strict selection of patients, use of a single stent-graft manufacturer, industry support and endovascular preceptorship. Our experience may be used as a model by other institutions in Canada. 相似文献
47.
Guy J Petruzzelli Kelly Cunningham Darl Vandevender 《Otolaryngology--head and neck surgery》2007,137(5):717-721
OBJECTIVE: To determine the role of native condyle preservation in local recurrence after segmental mandibulectomy in patients with head and neck squamous cell carcinoma. METHODS: Retrospective chart review with main outcome measuring local control of cancer. RESULTS: Between 1994 and 2003, 72 patients (48 men, 24 women) with an average age of 73.5 years without previous treatment underwent segmental mandibulectomy. Fifty-four cases (n = 54) involved the mandible posterior to the mental foramen and are the subject of this review. In 36 patients, the condyle was preserved and mandibular continuity was restored. In 18 patients, condyle and ramus were resected without mandibular reconstruction. Reconstructive modalities included primary closure (3), split-thickness skin graft (3), pedicle flap (19), and free tissue reconstructions (29). Overall local-regional recurrence rate was 22 percent (12 of 54); no recurrences were identified in patients who underwent condylar resection. Recurrences were observed in patients with mandibular reconstruction by both plate and pedicle flap (5 of 9) or (osteo) myocutaneous free flap (7 of 27). CONCLUSION: Condylar preservation may predispose patients to local recurrence after segmental mandibulectomy. This does not translate into overall reduction in survival. 相似文献
48.
A W Guy 《Health physics》1987,53(6):569-584
The interpretation of the effects in biological systems exposed to electromagnetic (EM) fields requires knowledge of the internal fields and absorbed energy. The quantification of the specific absorption rate (SAR) is called dosimetry. The SAR given in units of watts per kilogram is a complex function of the source configuration, shape and size of the exposed subjects, orientation of the subject with respect to the source, and the frequency. The average and maximum SAR in the exposed subject may vary over many orders of magnitude for a given exposure level. In order to relate observed biological effects in exposed laboratory animals to safe exposure levels for man, both the fields within the environment and SAR within the exposed tissues must be determined. The environmental fields and the SAR can often be determined from EM theory, but in most cases one must rely on instrumentation such as field survey meters for quantifying the exposure fields and electric field probes, thermocouples, thermistors, fiber optic probes, thermography, and calorimetry for quantifying the SAR in the tissues or equivalent models. A combination of techniques, each valid for a particular model over a particular frequency range, have been used to determine average and peak SARs in humans and animals exposed to plane wave radiation. Though it has been considerably more difficult to quantify these quantities for near field and partial-body exposure conditions, progress is continually being made in this area. 相似文献
49.
In this study 1,466 cases of primary lung cancer diagnosed between 1974 and 1983 and reported to the Provincial Tumour Registry, were reviewed. The incidence of lung cancer in Newfoundland has been lower than that in Canada as a whole. The age-adjusted rates for Canadian males and females were 56 and 14 per 100,000 compared to 45 and 7 in Newfoundland. Census division rates showed no association with socioeconomic indicators. The rate in one census division was higher (63 vs 53) most probably because of the higher risk of men who worked in the St. Lawrence fluorspar mines. Although Newfoundland's current smoking rates (39% of men over 15 and 29% of women over 15) are high, this is not reflected in lung cancer rates. Smoking was not widely accepted in rural areas until the time of World War II, and Newfoundland's lower rates may be due to this delay in exposure. 相似文献
50.