全文获取类型
收费全文 | 50419篇 |
免费 | 3969篇 |
国内免费 | 1535篇 |
专业分类
耳鼻咽喉 | 629篇 |
儿科学 | 1213篇 |
妇产科学 | 1023篇 |
基础医学 | 6386篇 |
口腔科学 | 757篇 |
临床医学 | 4861篇 |
内科学 | 8804篇 |
皮肤病学 | 1073篇 |
神经病学 | 3482篇 |
特种医学 | 1629篇 |
外国民族医学 | 14篇 |
外科学 | 6457篇 |
综合类 | 4495篇 |
现状与发展 | 4篇 |
一般理论 | 42篇 |
预防医学 | 4853篇 |
眼科学 | 1633篇 |
药学 | 3647篇 |
21篇 | |
中国医学 | 1221篇 |
肿瘤学 | 3679篇 |
出版年
2024年 | 88篇 |
2023年 | 614篇 |
2022年 | 1281篇 |
2021年 | 1989篇 |
2020年 | 1306篇 |
2019年 | 1478篇 |
2018年 | 1706篇 |
2017年 | 1390篇 |
2016年 | 1412篇 |
2015年 | 1780篇 |
2014年 | 2260篇 |
2013年 | 2490篇 |
2012年 | 3750篇 |
2011年 | 3845篇 |
2010年 | 2235篇 |
2009年 | 1830篇 |
2008年 | 2746篇 |
2007年 | 2851篇 |
2006年 | 2753篇 |
2005年 | 2578篇 |
2004年 | 2082篇 |
2003年 | 1848篇 |
2002年 | 1623篇 |
2001年 | 1129篇 |
2000年 | 1091篇 |
1999年 | 1020篇 |
1998年 | 531篇 |
1997年 | 460篇 |
1996年 | 346篇 |
1995年 | 358篇 |
1994年 | 300篇 |
1993年 | 213篇 |
1992年 | 454篇 |
1991年 | 426篇 |
1990年 | 434篇 |
1989年 | 423篇 |
1988年 | 358篇 |
1987年 | 343篇 |
1986年 | 310篇 |
1985年 | 252篇 |
1984年 | 179篇 |
1983年 | 128篇 |
1982年 | 72篇 |
1981年 | 83篇 |
1979年 | 118篇 |
1978年 | 70篇 |
1977年 | 69篇 |
1974年 | 86篇 |
1973年 | 83篇 |
1972年 | 84篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Performance standards for toric soft contact lenses. 总被引:1,自引:0,他引:1
Jacqueline Tan Eric Papas Nicole Carnt Isabelle Jalbert Cheryl Skotnitsky Maki Shiobara Edward Lum Brien Holden 《Optometry and vision science》2007,84(5):422-428
PURPOSE: To simplify the clinical assessment of toric soft contact lens (TSCL) on-eye behavior by establishing a set of standard clinical evaluation techniques. The likely performance range expected among the TSCL wearing population was determined for a series of lens designs and acceptable performance standards indicated for each variable. METHODS: Four prism-ballast, two peri-ballast and one dynamic stabilization TSCL designs were each worn by groups of 20 subjects in a nondispensing study. After 20 min of lens wear, lenses were assessed, in right eyes only, for subjective comfort (100-point scale), lens mislocation (degrees deviation from vertical) and rotational recovery after deliberate 30 degrees mislocation (degrees/10 blinks). The percentage of lenses orienting within +/-10 degrees of target orientation (zero rotation) and the variability of orientation (standard deviation of mislocation) were also calculated for each lens group. RESULTS: Based on partitioning of the data distributions for each variable, performance was designated as excellent, acceptable or poor. Corresponding performance cut-offs were determined at > or =90, 89 to 80, and <80 for subjective comfort, < or =+/-6 degrees , +/-7 degrees to 10 degrees , and >+/-10 degrees for mislocation, >10 degrees /10 blinks, 10 degrees to 6 degrees /10 blinks, and <6 degrees /10 blinks for rotational recovery. For groups of wearers the appropriate cut-offs were > or =90%, 89 to 70%, and <70% of lenses orienting within +/-10 degrees of target orientation and <+/-6 degrees , +/-6 degrees to 10 degrees , and >+/-10 degrees for variability of orientation. CONCLUSION: Techniques suitable for the evaluation of TSCL clinical performance have been described and guidelines for the assessment of such lenses established. In the process, we have identified potential performance differences that may relate to variations in TSCL design. 相似文献
122.
123.
124.
Acute Cellular Rejection with CD20-Positive Lymphoid Clusters in Kidney Transplant Patients Following Lymphocyte Depletion 总被引:1,自引:0,他引:1
L. K. Kayler F. G. Lakkis C. Morgan A. Basu D. Blisard H. P. Tan J. McCauley C. Wu R. Shapiro P. S. Randhawa 《American journal of transplantation》2007,7(4):949-954
Lymphoid clusters (LC) containing CD20-positive B cells in kidney allografts undergoing acute cellular rejection (ACR) have been identified in small studies as a prognostic factor for glucocorticoid resistance and graft loss. Allograft biopsies obtained during the first episode of ACR in 120 recipients were evaluated for LC, immunostained with CD20 antibody, and correlated with conventional histopathologic criteria, response to treatment and outcome. LC were found in 71 (59%) of the 120 biopsies. All contained CD20 positive B cells that accounted for 5-90% of the LC leukocyte content. The incidence of LC was highest in the patients who had no lymphoid depletion or had been treated with Thymoglobulin preconditioning (79% vs. 75%, respectively) compared to 37% in patients pretreated with Campath (p = 0.0001). Banff 1a/1b ACR were more frequent in the LC-positive than the LC-negative group (96% vs. 80%, respectively; p = 0.0051). With a posttransplant follow-up of 953 +/- 430 days, no significant differences were detected between LC-postitive and LC-negative groups in time to ACR, steroid resistance, serum creatinine and graft loss. CD20+LC did not portend glucocorticoid resistance or worse short to medium term outcomes. CD20+LC may represent a heterogenous collection in which there may be a small still to be fully defined unfavorable subgroup. 相似文献
125.
126.
Tumor necrosis factor-alpha in whole blood cultures of preeclamptic patients and healthy pregnant and nonpregnant women. 总被引:4,自引:0,他引:4
Ilse Beckmann Shlomo Ben Efraim Monica Vervoort Wil Visser Henk C S Wallenburg 《Hypertension in pregnancy》2004,23(3):319-329
OBJECTIVES: Tumor necrosis factor-alpha (TNF-alpha) is recognized as a likely mediator of the excessive endothelial activation and injury that is a key pathogenetic mechanism of preeclampsia. We used whole blood cell cultures from 12 patients with severe preeclampsia and from 12 healthy pregnant and nonpregnant women to determine the release of TNF-alpha by unstimulated leukocytes as a measure of their state of activation, and their response to stimulation with lipopolysaccharide (LPS) as an indicator of their state of priming. METHODS: Blood was cultivated without and with LPS, and TNF-alpha release was measured after six and 24 hours of cultivation by enzyme-linked immunoassays. Differential leukocyte counts were performed, and TNF-alpha values calculated per 10(5) monocytes. RESULTS: In unstimulated whole blood cultures, TNF-alpha release after six hours of cultivation was similar in all three groups; but after 24 hours, TNF-alpha concentrations in culture supernatants from preeclamptic patients were significantly higher than were values obtained in blood from normotensive pregnant women. In LPS-stimulated blood cultures with a maximum of TNF-alpha release at six hours cultivation time, TNF-alpha concentrations were significantly lower in preeclamptic women than they were in both control groups. We showed in an additional experiment that a strong LPS challenge following preactivation with high doses of LPS resulted in reduced release of TNF-alpha compared with release of TNF-alpha following preactivation with low doses of LPS. CONCLUSIONS: The observed high capacity for spontaneous TNF-alpha release by leukocytes in preeclampsia indicates activation of TNF-alpha producing leukocytes by the disease process. Preactivation and exhaustion of leukocytes by leakage of TNF-alpha could lead to the reduced response to TNF-alpha inducer LPS as observed in blood cultures from preeclamptic patients. 相似文献
127.
目的探讨肾动脉狭窄支架植入术的临床疗效.方法1997年1月~2004年12月,我院行支架介入治疗肾动脉狭窄27例.对27例术前、术后及随访期内血压、肾功能以及生活质量进行评估,并与同期单纯药物治疗肾动脉狭窄27例进行比较.结果介入组27例植入支架40枚,手术成功24例(88.9%,24/27),失败3例(11.1%,3/27),手术并发症5例(18.5%,5/27).术后在血压下降(包括收缩压舒张压)肌酐下降,肾小球滤过率增加方面,介入组获益率明显优于药物组,两组比较差异均有显著性,术后随访6个月~8年6个月,中位数为1年9个月,介入组有19例能比较健康的生活和工作,药物组仅12例能维持生活和工作.结论支架介入治疗较单纯药物治疗肾动脉狭窄疗效显著. 相似文献
128.
Greg A Kossena William N Charman Ben J Boyd Christopher J H Porter 《Journal of controlled release》2004,99(2):217-229
The existence of a novel cubic liquid crystalline phase is described within the pseudo-ternary system comprising lauric acid, monolaurin, and simulated endogenous intestinal fluid (SEIF). This phase behaviour has been characterized using cross-polarizing light microscopy (CPLM), and the structure of the cubic phase identified by small angle X-ray scattering (SAXS). The presence of the cubic phase was found to be temperature sensitive within the 20-37 degrees C range making it putative material for in situ gelation purposes. The cubic phase was shown to have a high capacity to solubilise a model poorly water-soluble drug, cinnarizine, and initial in vitro release data highlight the potential of this phase to provide sustained release. Absorption of cinnarizine from the cubic phase was studied in an unconscious rat model via duodenal administration and blood sampling via the carotid artery. The rate of absorption was significantly reduced when compared to a simple suspension formulation, a likely combination of retarded erosion of the cubic phase together with hindered drug release from the cubic matrix. The results of this study suggest that this cubic phase may potentially be of benefit in the delivery of poorly water-soluble compounds due to its high loading capacity and potential for sustained release. The ability to manipulate this system using temperature may warrant further interest in delivery applications via other routes of administration. 相似文献
129.
Thomas Rimmelé Sophie Malhière Alexandre Ben Cheikh Emmanuel Boselli Monique Bret Charles-Eric Ber Paul Petit Bernard Allaouchiche 《Journal canadien d'anesthésie》2007,54(8):652-656
PURPOSE: In France, legislation mandates that the clinical diagnosis of brain death be confirmed by one paraclinical test before organ donation is allowed. That test may be either the electroencephalogram (EEG) or cerebral angiography. We report a case in which the clinical diagnosis of brain death was first confirmed by two EEGs performed according to the French guidelines, but ruled out by cerebral angiography. Considering that the EEG is no longer recommended to establish the diagnosis of brain death, we discuss the relevance of maintaining the EEG for brain death diagnosis in France. CLINICAL FINDINGS: A 58 yr-old man was admitted to the intensive care unit because of coma secondary to a massive subarachnoid hemorrhage with herniation below the falx shown by computed tomography. Clinical criteria of brain death were rapidly present. Two EEGs first confirmed the diagnosis but a four-vessel cerebral angiography was finally performed because the patient moved spontaneously. This cerebral angiography showed flow in the right internal carotid artery. A computed tomography performed the next day definitely confirmed the absence of brain death and organ donation did not occur. CONCLUSIONS: This case demonstrates the limitations of the EEG for this indication and suggests that angiography should be preferred. French legislation is probably maladjusted and would benefit by incorporating guidelines of other countries like Canada. International harmonization of criteria for brain death diagnosis would also be welcome. 相似文献
130.
去带盲升结肠可控膀胱术后远期并发症(附105例报告) 总被引:2,自引:0,他引:2
目的 探讨去带盲升结肠可控膀胱术后远期并发症的发生及防治.方法 回顾性分析1995年10月至2003年1月105例去带盲升结肠可控膀胱术后患者资料.男83例,女22例.年龄32~78岁,平均60岁.随访时间9~82个月,平均40.5个月.结果 发生远期并发症27例(25.7%),其中导尿插管困难4例(3.8%),3例行尿道扩张后治愈,1例再次手术利用末段回肠重建输出道;贮尿囊结石5例(4.8%),4例行贮尿囊切开取石治愈,1例无自觉症状者未行处理;贮尿囊穿孔1例(0.9%),行手术修补后痊愈;贮尿囊过度扩张1例(0.9%),行贮尿囊缩小术;肾积水8例(7.6%),合并输尿管返流1例,合并下段输尿管狭窄4例,其中2例行狭窄段输尿管切除再吻合,1例术前为氮质血症者发展为尿毒症需行规律血透;血氯增高7例(6.7%),1例出现高氯性酸中毒需长期口服碳酸氢钠;单纯表现为症状性泌尿系感染1例(0.9%).27例中另合并症状性泌尿系感染10例,根据尿培养结果予敏感抗生素治愈.结论 去带盲升结肠可控膀胱术后远期并发症多与症状性泌尿系感染相关,积极防治泌尿系感染,规律、充分的贮尿囊冲洗及定时清洁导尿对远期并发症的预防有重要作用. 相似文献