全文获取类型
收费全文 | 233690篇 |
免费 | 19894篇 |
国内免费 | 9734篇 |
专业分类
耳鼻咽喉 | 2449篇 |
儿科学 | 5227篇 |
妇产科学 | 2586篇 |
基础医学 | 36795篇 |
口腔科学 | 5749篇 |
临床医学 | 22725篇 |
内科学 | 33111篇 |
皮肤病学 | 4721篇 |
神经病学 | 12642篇 |
特种医学 | 6360篇 |
外国民族医学 | 122篇 |
外科学 | 19342篇 |
综合类 | 38012篇 |
现状与发展 | 53篇 |
预防医学 | 9289篇 |
眼科学 | 4257篇 |
药学 | 19392篇 |
103篇 | |
中国医学 | 11971篇 |
肿瘤学 | 28412篇 |
出版年
2024年 | 551篇 |
2023年 | 3321篇 |
2022年 | 5778篇 |
2021年 | 8515篇 |
2020年 | 7686篇 |
2019年 | 7049篇 |
2018年 | 7153篇 |
2017年 | 7666篇 |
2016年 | 8074篇 |
2015年 | 8909篇 |
2014年 | 13820篇 |
2013年 | 15169篇 |
2012年 | 13082篇 |
2011年 | 14473篇 |
2010年 | 11822篇 |
2009年 | 11180篇 |
2008年 | 11758篇 |
2007年 | 12069篇 |
2006年 | 10957篇 |
2005年 | 10032篇 |
2004年 | 8935篇 |
2003年 | 7847篇 |
2002年 | 6568篇 |
2001年 | 5809篇 |
2000年 | 4801篇 |
1999年 | 4280篇 |
1998年 | 4039篇 |
1997年 | 3859篇 |
1996年 | 3353篇 |
1995年 | 3048篇 |
1994年 | 2776篇 |
1993年 | 2246篇 |
1992年 | 1949篇 |
1991年 | 1788篇 |
1990年 | 1395篇 |
1989年 | 1325篇 |
1988年 | 1267篇 |
1987年 | 1004篇 |
1986年 | 948篇 |
1985年 | 1270篇 |
1984年 | 1092篇 |
1983年 | 740篇 |
1982年 | 888篇 |
1981年 | 679篇 |
1980年 | 596篇 |
1979年 | 445篇 |
1978年 | 339篇 |
1977年 | 283篇 |
1976年 | 233篇 |
1975年 | 105篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Johannes Woitzik Elke Lassel Ulf C. Schneider Helmut Schroeck Rudolf Graf 《Experimental neurology》2009,218(1):41-350
Lesion evolution during focal cerebral ischemia may depend on flow restrictions or on accumulation of toxic mediators within the infarct and expansion of these factors to the periinfarct region. So far, the precise contribution of flow dependent versus spreading-mediated impairment of viable periinfarct tissue has not been determined. Therefore, we measured lesion expansion, flow restrictions and glutamate distribution on serial brain sections at different time points after experimental focal ischemia.Permanent focal ischemia was induced by occlusion of the right middle cerebral artery in male rats and the flow reduction was subsequently measured at 1, 12 and 24 h using iodo[14C]antipyrine autoradiography. Additionally, the necrotic volume was determined on serial brain sections and the glutamate content was measured in tissue samples from adjacent microdissections.Twelve hours after focal ischemia no noteworthy viable areas with blood flow restrictions of 20-40 ml 100 g− 1 min− 1 existed but at 24 h the necrotic tissue exceeded the hemodynamically compromised region by 40 ± 21 mm3 (24%). Furthermore, at 12 and 24 h the glutamate content was elevated in areas surrounding the infarct.Relevant flow restrictions are detectable only during early stages of infarct maturation, whereas the propagation of secondary factors may be the predominant mechanism for delayed infarct evolution. 相似文献
53.
Seunghan Ha Minhee Lee Onseok Lee Gunwoo Lee Jeayoung Kim Jongsub Moon Mingi Kim Chilhwan Oh 《Skin research and technology》2009,15(2):200-213
Background/aims: The objective and quantitative assessment of the skin is important in medical and cosmeceutical research. Assessment of color is an important element for analyzing the surface of the skin, which is usually determined subjectively by a doctor or using color analysis devices. These devices, however, cannot provide correct color information because color is construed from the mean value of the observation region, and analysis of color distribution is impossible. The purpose of this paper is to develop an objective analysis method to permit skin color measurement of each pixel unit of an image and analyze the distribution of skin surface color. Methods: The Skin Color Distribution Analyzer (SCDA) is an analysis method newly developed at the Research Institute for Skin Image at Korea University. The SCDA system presented in this paper performed a novel form of quantitative and objective analysis of skin color distribution using each pixel color model parameter found in image wavelength information. In this paper, distribution analysis was conducted on normal skin and skin lesions and skin affected by artificially induced irritant contact dermatitis and pigmented nevous. The method selected a grade using a color model parameter. Twenty healthy Korean males participated in this study. A comparative study of the eight anatomical areas was performed, including the exposure and non‐exposure parts and the medial aspect and the lateral aspect of the forearm. A reliability test for the SCDA system was also conducted with a spectrometer (SPEC) using the color analysis method. Results: Each skin lesion was precisely segmented by grade and each parameter hada different statistical significance for results of analysis of distribution in pigmented nevous and the artificially induced irritant contact dermatitis. Parameters L*, b*, a*, and EI showed salient traits. Showed resemble measured result in the SCDA system and the SPEC of normal skin. The exposed site, in comparison with the non‐exposed site, showed a notable difference in the L* parameter and a significant statistical difference in the x and z parameters, except b*. The comparison of the medial and lateral aspects of the forearm showed a notable difference in the L* parameter and a significant statistical difference in the parameters except y and b*. In the reliability test result using the SCDA system and the SPEC, the SCDA system was highly reliabile in terms of the CV value in all color model parameters. Conclusions: The color distribution analysis method using the SCDA system has revealed an aspect that the existent method of medical research has not shown, and is considered to be more reliable than other methods. This method can provide better study findings because it can be applied to other fields in addition to the medical science field and the ripple effect is thought to be bigger in other science field too. 相似文献
54.
G Gaitanis K Nomikos E Vava EC Alexopoulos ID Bassukas 《Journal of the European Academy of Dermatology and Venereology》2009,23(12):1427-1431
Background/aim Theoretical considerations support the combination of cryosurgery and topical imiquimod to treat basal cell carcinomas (BCC). The aim of the present study was to test the feasibility and efficacy of 'cryosurgery during continued imiquimod application' ('immunocryosurgery') to treat 'high-risk-for-recurrence' BCCs.
Methods Thirteen patients with 21 biopsy-proven tumours (4 of 21 relapses after prior surgery) were included. After 2–5 weeks (median, 3) of daily 5% imiquimod cream application, the tumours were treated by liquid N2 cryosurgery (spray, two cycles, 10–20 s) and imiquimod was continued for additional 2–12 weeks (median, 4). The outcome after at least 18 months of follow-up (18–24 months) is currently reported.
Results Nineteen of 21 tumours responded promptly to immunocryosurgery; two tumours required additional treatment cycles to clear. Thus, the clinical clearance rate was 100%. Only 1 of 21(5%) tumour relapsed after at least 18 months of follow-up (cumulative efficacy: 95%).
Conclusions 'Immunocryosurgery' is a promising non-surgical combination modality to treat 'high-risk-for-recurrence BCCs'. Initial evidence is suggestive of an at least additive effect of the two combined modalities. Further studies comparing immunocryosurgery directly with cryosurgery and imiquimod monotherapies will confirm the reported results. 相似文献
Methods Thirteen patients with 21 biopsy-proven tumours (4 of 21 relapses after prior surgery) were included. After 2–5 weeks (median, 3) of daily 5% imiquimod cream application, the tumours were treated by liquid N
Results Nineteen of 21 tumours responded promptly to immunocryosurgery; two tumours required additional treatment cycles to clear. Thus, the clinical clearance rate was 100%. Only 1 of 21(5%) tumour relapsed after at least 18 months of follow-up (cumulative efficacy: 95%).
Conclusions 'Immunocryosurgery' is a promising non-surgical combination modality to treat 'high-risk-for-recurrence BCCs'. Initial evidence is suggestive of an at least additive effect of the two combined modalities. Further studies comparing immunocryosurgery directly with cryosurgery and imiquimod monotherapies will confirm the reported results. 相似文献
55.
H. Kurokawa M. Zhang S. Matsumoto Y. Yamashita T. Tomoyose T. Tanaka H. Fukuyama T. Takahashi 《Journal of oral pathology & medicine》2005,34(6):329-333
BACKGROUND: Although many histopathologic factors in squamous cell carcinoma of the tongue predict the prognosis, the major predictive factors have not been identified clearly. This study analyzed the prognostic value of the histologic grade at the deep invasive front of tongue squamous cell carcinoma. METHODS: The clinicopathologic features of 124 consecutive patients seen between January 1985 and December 1999 with previously untreated squamous cell carcinoma of the tongue were reviewed. Their mean age was 58.5 years (range: 23-90) and the male-female ratio was 1.8: 1 (79 men and 45 women). There were 41, 40, 30, and 13 cases at stage I to stage IV, respectively. The clinicopathologic factors, especially the histologic grade at the deep invasive front (invasive front grade, IFG), were analyzed to determine factors predicting prognosis. RESULTS: The 5-year disease-free survival rate of the patients treated with curative aim only was 66.7%. Clinicopathologic factors significantly associated with the prognosis were T classification, tumor size, stage classification, tumor depth, macroscopic appearance, cervical lymph node metastasis (nodal metastasis), microvascular invasion, and IFG. In a multivariate analysis, patients with tumor depth >/=4 mm, IFG >/=8 points, and nodal metastasis had a reduced disease-free survival and IFG >/=11 points had a predictive value for nodal metastasis (odds ratio: 7.34; P = 0.0019). CONCLUSION: This study found that a high IFG malignancy score had a high prognostic value for squamous cell carcinoma of the tongue. 相似文献
56.
Transplantation of microencapsulated bovine chromaffin cells reduces lesion-induced rotational asymmetry in rats 总被引:7,自引:0,他引:7
Surrounding bovine chromaffin cells by a semipermeable membrane may protect the transplanted cells from a host immune response and shield them from the inflammatory process resulting from the surgical trauma. Encapsulation of the chromaffin cells was achieved by inter-facial adsorption of a polycation on a polyanionic colloid matrix in which the chromaffin cells were entrapped. Basal and potassium-evoked release of catecholamines from encapsulated bovine chromaffin cells was analyzed over a 4-week period in vitro. Norepinephrine and dopamine release remained constant over time whereas epinephrine release significantly decreased. The chromaffin cells also retained the capacity for depolarization-elicited catecholamine release 4 weeks following the encapsulation procedure. Morphological analysis revealed the presence of intact chromaffin cells with well-preserved secretory granules. Striatial implantation of chromaffin cell-loaded capsules significantly reduced apomorphine-induced rotation compared to empty polymer capsules in animals lesioned with 6-hydroxydopamne frr at least 4 weeks. Intact chromaffin cells expressing tyrosine hydroxylase and dopamine-β-hydroxylase were observed in all capsules implanted in the striatum for 4 weeks. The assessment of the clinical potential of transplanting encapsulated adrenal chromaffin cells of either allo- or xenogeneic origin for Parkinson's disease will require long-term behavioral studies. The present study suggests, however, that the polymer encapsulation procedure may offer an alternative to adrenal autografts as a source of dopaminergic tissue. 相似文献
57.
58.
Objective To obtain the dendritic cells ( DC)-based vaccine modified by adenovirus containing MUC4 gene , and evaluate the anti-tumor efficacy of DC vaccine to pancreatic tumor cells. Meth-ods The mRNA sequence of tumor associated antigen, MUC4, was obtained from NCBI, and MUC4 se-quence was acquired through the restriction enzyme sites and over lap PCR, then subcloned into adenovirus plasmid to create recombinant adenovirus ( rAd-MUC4) . The DCs were infected by rAd-MUC4 virus and then stimulated the lymph cells from the same donor to induce MUC4 specific cytotoxicity T lympbocytes ( CTL) . The efficacy of CTL was analyzed by LDH releasing assay. Elispot was used to detect the IFN-γ release. Results The recombinant adenovirus containing MUC4 ( sv12) gene was obtained. The MUC4-induced CTL could specifically kill the Capan-1 pancreatic tumor cells [ ( 13. 7±6.0)% , ( 21.4± 4. 7)% , (36.1±9. 5)% at ratios of 10: ,20: ,40: ] , higher than MCF-7 and Bxpc-3 cells respectively, P < 0. 05. The spots number of CTL induced by rAd-MUC4 was ( 139.1±23.3) , more than GFP and PBS control group,P<0.05. Conclusion The Muc4 gene modified DC vaccine could induce the proliferation of CTL, which provided a significant cytotoxicity to HLA-matched MUC4 positive tumor cell lines in vitro. 相似文献
59.
T. Saarne L. Kaiser H. Grönlund O. Rasool G. Gafvelin M. van Hage-Hamsten 《Clinical and experimental allergy》2005,35(5):657-663
BACKGROUND: Allergen-specific immunotherapy is the only treatment for allergic disease providing long-lasting symptom relief. Currently, it is mainly based on the use of crude allergen extracts. The treatment may be improved by the use of genetically engineered allergens, hypoallergens, aiming at a more effective and safer therapy. OBJECTIVE: The aim of this study was to provide a rational design of hypoallergen candidates for immunotherapy by using structural information and knowledge of B and T cell epitopes of an allergen. METHODS: The three-dimensional structure of the major cat allergen Fel d 1 was systematically altered by duplication of selected T cell epitopes and disruption of disulphide bonds. Seven Fel d 1 derivatives were generated and screened for allergenic reactivity in comparison with recombinant Fel d 1 in competition-ELISA. The allergenicity was further evaluated in basophil activation experiments and T cell reactivity was assessed in a lymphoproliferation assay. RESULTS: Three out of seven Fel d 1 derivatives, with two duplicated T cell epitopes and one or two disulphide bonds disrupted, were carefully evaluated. The three derivatives displayed a strong reduction in allergenicity with 400-900 times lower IgE-binding capacity than recombinant Fel d 1. In addition, they induced a lower degree of basophil activation and similar or stronger T cell proliferation than recombinant Fel d 1. CONCLUSION: By a rational approach, we have constructed three Fel d 1 hypoallergens with reduced IgE-binding capacities and retained T cell reactivities. This strategy may be applied to any well-characterized allergen to improve immunotherapy for allergic patients. 相似文献
60.