全文获取类型
收费全文 | 22167篇 |
免费 | 1989篇 |
国内免费 | 987篇 |
专业分类
耳鼻咽喉 | 232篇 |
儿科学 | 552篇 |
妇产科学 | 252篇 |
基础医学 | 2501篇 |
口腔科学 | 511篇 |
临床医学 | 2494篇 |
内科学 | 4048篇 |
皮肤病学 | 379篇 |
神经病学 | 1336篇 |
特种医学 | 751篇 |
外国民族医学 | 5篇 |
外科学 | 2129篇 |
综合类 | 2669篇 |
现状与发展 | 4篇 |
一般理论 | 2篇 |
预防医学 | 1696篇 |
眼科学 | 716篇 |
药学 | 2058篇 |
24篇 | |
中国医学 | 1129篇 |
肿瘤学 | 1655篇 |
出版年
2024年 | 77篇 |
2023年 | 348篇 |
2022年 | 826篇 |
2021年 | 1152篇 |
2020年 | 864篇 |
2019年 | 785篇 |
2018年 | 922篇 |
2017年 | 778篇 |
2016年 | 681篇 |
2015年 | 980篇 |
2014年 | 1144篇 |
2013年 | 1188篇 |
2012年 | 1707篇 |
2011年 | 1727篇 |
2010年 | 1094篇 |
2009年 | 773篇 |
2008年 | 1115篇 |
2007年 | 1128篇 |
2006年 | 929篇 |
2005年 | 976篇 |
2004年 | 778篇 |
2003年 | 756篇 |
2002年 | 690篇 |
2001年 | 546篇 |
2000年 | 617篇 |
1999年 | 504篇 |
1998年 | 182篇 |
1997年 | 176篇 |
1996年 | 161篇 |
1995年 | 140篇 |
1994年 | 104篇 |
1993年 | 84篇 |
1992年 | 190篇 |
1991年 | 150篇 |
1990年 | 133篇 |
1989年 | 131篇 |
1988年 | 112篇 |
1987年 | 92篇 |
1986年 | 80篇 |
1985年 | 59篇 |
1984年 | 45篇 |
1983年 | 25篇 |
1982年 | 18篇 |
1981年 | 14篇 |
1980年 | 15篇 |
1979年 | 15篇 |
1977年 | 12篇 |
1973年 | 9篇 |
1970年 | 9篇 |
1965年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The purpose of this research is to explore the feasibility of using calcium carbide residue (CCR), a by-product from acetylene gas production, as a solid alkaline activator on the strength development in CCR–Portland cement-stabilized dredged sludge (CPDS). The effects of cement content, CCR content and curing time on the strength development of CPDS were investigated using a series of unconfined compressive strength (UCS), pH and electric conductivity (EC) tests. Scanning electron microscopy and X-ray diffraction analyses were performed to gain additional insight into the mechanism of strength development. Meanwhile, the carbon footprints of CPDS were calculated. Following the results, it was found that CCR can significantly improve the strength of cemented dredged sludge. On the basis of the strength difference (ΔUCS) and strength growth rate (UCSgr), it was recommended that utilizing 20% cement with the addition of 20% CCR is the most effective way to develop the long-term strength of CPDS. In addition, the microstructural analysis verified that the optimum proportion of CCR benefits the formation of hydration products in CPDS, particularly needle-like gel ettringite, resulting in a less-porous and dense inter-locked structure. Furthermore, the solidification mechanism of CPDS was discussed and revealed. Finally, it was confirmed that CCR can be a sustainable alternative and effective green alkaline activator for the aim of improving cemented dredged sludge. 相似文献
102.
Energy harvesting devices made of piezoelectric material are highly anticipated energy sources for power wireless sensors. Tremendous efforts have been made to improve the performance of piezoelectric energy harvesters (PEHs). Noticeably, topology optimization has shown an attractive potential to design PEHs with enhanced energy conversion efficiency. In this work, an alternative yet more practical design objective was considered, where the open-circuit voltage of PEHs is enhanced by topologically optimizing the through-thickness piezoelectric material distribution of plate-type PEHs subjected to harmonic excitations. Compared to the conventional efficiency-enhanced designs, the open-circuit voltage of PEHs can be evidently enhanced by the proposed method while with negligible sacrifice on the energy conversion efficiency. Numerical investigations show that the voltage cancellation effect due to inconsistent voltage phases can be effectively ameliorated by optimally distributed piezoelectric materials. 相似文献
103.
为了观察人工组织神经移植物对大鼠坐骨神经非新鲜损伤的修复作用。我们在成年SD大鼠左侧股中部切除部分坐骨神经制造神经缺损模型。15d后,实验组(9只)用人工组织神经移植物修复神经缺损,自体神经修复作为阳性对照(6只),保持神经缺损为阴性对照(6只)。第二次手术后3个月,电生理学、形态学结果显示实验组的再生神经虽略差于自体对照组,但明显优于缺损对照组,腓肠肌的萎缩形态学指标变化则较接近自体对照组。实验结果表明人工组织神经移植物对已缺损15d的大鼠周围神经具有较好修复作用。 相似文献
104.
Rationale:To report a rare case of calculating the IOL power in a cataract patient who underwent both radial keratotomy (RK) and photorefractive keratectomy (PRK).Patient concerns:A 48-year-old woman underwent bilateral RK at age 22 and bilateral PRK at age 46. She developed bilateral corneal haze and corneal endothelial inflammation and received steroids therapy for long time after PRK. Then she was referred to our hospital due to decreased vision in the both eyes.Diagnoses:The patient was diagnosed with binocular complicated cataract, corneal haze, high myopia and post corneal refractive surgery (RK and PRK).Interventions:The patient underwent bilateral phacoemulsification. The IOL power was calculated using SRK/T formula for RK and Haigis-L formula for PRK, respectively. We finally selected the Haigis-L formula and the intraocular lens (SN60WF) was implanted within the capsular bag.Outcomes:After the surgery, both eyes showed myopia drift, and the right eye continuously fluctuated in refractive results. However, by nearly 1 year later, refractive results in both eyes had stabilized, and no other complications had occurred.Lessons:IOL power in patients who undergo both RK and PRK can be reliably calculated using the Shammas-PL, Average of multiple formulas, or Barret True-K No History formulas. Haigis-L formula is not suitable. Such patients require at least three months after surgery to attain refractive stability in both eyes. 相似文献
105.
Rationale:Femtosecond laser-assisted cataract surgery (FLACS) has grown in popularity among ophthalmologists as a novel surgical technique. However, malignant glaucoma (MG) is a complication of FLACS. Herein, we report a case of MG following FLACS.Patient concerns:A 66-year-old woman presented with complaints of blurred vision in the right eye and a foreign body sensation in both eyes. Ophthalmological examinations showed that the corrected distance visual acuity was 20/50 and 20/25 in the right and left eyes, respectively. Without any topical anti-glaucoma medication, the intraocular pressure (IOP) was 20 mmHg in the right eye and 17 mmHg in the left eye. Slit-lamp examination of the right eye revealed a transparent cornea with a defect in the punctate overlying epithelium; the central anterior chamber depth was shallow the peripheral iris laser shot was visible, the pupil was normal, and the lens was mainly cortical opacified.Diagnoses:Based on the patient''s symptoms, examination results, and preliminary diagnoses, age-related cataract in the right eye, binocular post-antiglaucoma surgery, pseudophakicin in the left eye, and Sjogren syndrome were included.Interventions:FLACS was performed to facilitate anterior capsulotomy and segmentation of the nucleus in the right eye. MG occurred after the femtosecond procedure, and with the treatment of medicines combined with phacoemulsification, IOP was eventually normal without further antiglaucoma therapy.Outcomes:IOP was 16 mmHg on postoperative day 1. Ocular ultrasonography revealed no choroid detachment or hemorrhage in the right eye. Two weeks postoperatively, uncorrected visual acuity was 20/25, and IOP remained normal with no further antiglaucoma treatment on 1 month postoperatively.Conclusions:We describe the occurrence of MG after FLACS and illustrate that miosis and bubble formation after FLACS may be risk factors for MG during FLACS. 相似文献
106.
The high-dose glucocorticosteroid (GC) treatment is the first choice for dermatomyositis complicated with interstitial lung disease (DM-ILD) but patients are resistant to the high-dose GC monotherapy. Besides, the high dose of GC, the secondary immunosuppressive agent(s) is necessary but there is controversy for the selection of immunosuppressive agent(s). The objectives of the study were to analyze the efficacy of different therapeutic options for DM-ILD to identify the optimal therapy. A total of 60 patients had received intravenous 1.0–2.0 mg/ kg/day prednisolone for DM-ILD. In severe conditions, patients had received oral 1 to 3 mg/day tacrolimus (TAC), 500 mg/ m2/month cyclophosphamide (CY), and/or 1 g/ day methylprednisolone pulse (TI cohort, n = 24). In severe conditions, patients had received 1 g/day methylprednisolone pulse and 2–3 mg/ kg/day cyclosporine A (CsA) and/or 500 mg/ m2/month CY (existing historical treatment; CT cohort, n = 36). Patients of the TI cohort did not receive CsA. Patients in the CT cohort were received CY in significantly fewer numbers than those of the TI cohort during treatment (P = .0112). A total of 11 (46%) patients from the TI cohort and 14 (39%) patients from the CT cohort were developed relapsed. At the end of the 30-months, higher numbers of patients of the TI cohort had an event(s) free survival than those of the CT cohort (7 (29%) vs 2 (6%), P = .0229). Also, higher numbers of patients of the TI cohort had survived irrespective of an event(s) than those of the CT cohort (21 (87%) vs 22 (61%), P = .0399). Patients of the TI cohort had developed herpes zoster (2 (8%)) and cytomegalovirus (4 (17%)) infections. Patients of the CT cohort developed renal dysfunction (10 (28%)). Hyperglycemia, hyperlipidemia, and fracture (GC-related toxicities) were also reported in both cohorts and these toxicities were fever in the TI cohort. The addition of TAC to high doses GC with CY is an ideal treatment for severe conditions of DM-ILD (Level of Evidence: III; Technical Efficacy Stage: 4). 相似文献
107.
Background:The purpose of this study was to evaluate the clinical outcomes and complications of displaced proximal humeral fractures treated with proximal humeral internal locking system (PHILOS) plate fixation via a deltoid interfascicular (DI) vs a deltopectoral (DP) approach.Methods:This prospective case-control study was conducted with patients admitted to our hospital from May 2015 to June 2018 who suffered from unilateral displaced proximal humerus fractures. Patients were treated with PHILOS plate fixation via a DI (DI group) or DP approach (DP group). The clinical outcomes and complication data were collected for comparison between the 2 groups. The patients were followed up at 3, 6, and 12 months; and every 6 months thereafter. The patients’ functional recoveries were evaluated according to the normalized Constant-Murley score, range of motion of the shoulder (flexion, abduction, external/internal rotation) and disabilities of the arm, shoulder and hand score.Results:A total of 77 patients, followed for an average of 15 ± 2.2months (range, 12–21), were enrolled (36 in DI group and 41 in DP group) for final analysis. No significant differences in age, sex, affected side, fracture type, injury mechanism or time from injury to operation were found between the 2 groups (all P > .05). The incision length, intra-operative blood loss, and duration of operation in the DI group were significantly less than those in the DP group, respectively (all P < .05). The functional outcomes assessed by the normalized Constant-Murley score and range of motion of flexion and internal rotation in the DI group were superior to those in the DP group at 3 and 6months after the operation (P < .05); however, no significant differences were observed at the 12-month and subsequent follow-ups (all P > .05). There was no significant difference in the range of shoulder external rotation and abduction during the postoperative follow-ups (P > .05). At the last follow-up, the mean disabilities of the arm, shoulder, and hand score was 14.0 (6.6) points in the DI group and 14.4 (6.9) points in the DP group (P = .793). Complications occurred in 1 patient in the DI group and 8 patients in the DP group (P = .049).Conclusion:The current study demonstrates that DI approach is a safe and effective alternative for the treatment displaced proximal humerus fractures. The DI approach rather than DP approach was recommended when lateral and posterior exposure of the proximal humerus is required, especially when fixed with PHILOS plate. 相似文献
108.
Xuan Han WuHu Zhang HeLi Gao TianJiao Li HuaXiang Xu Hao Li PengCheng Li Xu Wang XianJun Yu WenQuan Wang Liang Liu 《Journal of clinical laboratory analysis》2022,36(7)
BackgroundThe selective pressure imposed by chemotherapy creates a barrier to tumor eradication and an opportunity for metastasis and recurrence. As a newly discovered stemness marker of pancreatic ductal adenocarcinoma (PDAC), the impact of CD9 on tumor progression and patient''s prognosis remain controversial.MethodsA total of 179 and 211 PDAC patients who underwent surgical resection with or without neoadjuvant chemotherapy, respectively, were recruited for immunohistochemical analyses of CD9 expression in both tumor and stromal areas prior to statistical analyses to determine the prognostic impact and predictive accuracy of CD9.ResultsThe relationship between CD9 and prognostic indicators was not significant in the non‐neoadjuvant group. Nevertheless, CD9 expression in both tumor (T‐CD9) and stromal areas (S‐CD9) was significantly correlated with the clinicopathological features in the neoadjuvant group. High levels of T‐CD9 were significantly associated with worse OS (p = 0.005) and RFS (p = 0.007), while positive S‐CD9 showed the opposite results (OS: p = 0.024; RFS: p = 0.008). Cox regression analyses identified CD9 in both areas as an independent prognostic factor. The T&S‐CD9 risk‐level system was used to stratify patients with different survival levels. The combination of T&S‐CD9 risk level and TNM stage were accurate predictors of OS (C‐index: 0.676; AIC: 512.51) and RFS (C‐index: 0.680; AIC: 519.53). The calibration curve of the nomogram composed of the combined parameters showed excellent predictive consistency for 1‐year RFS. These results were verified using a validation cohort.ConclusionNeoadjuvant chemotherapy endows CD9 with a significant prognostic value that differs between tumor and stromal areas in patients with pancreatic cancer. 相似文献
109.
测定胃癌患者肿瘤组织与外周血中前列腺素E2的临床意义 总被引:4,自引:0,他引:4
目的 测定胃癌患者肿瘤组织及外周血中前列腺素E2(prostaglandin E2,PGE2)含量.方法 用PGE2酶联免疫试剂盒分别测定40例胃癌患者肿瘤组织、癌旁切缘组织及术前外周血中PGE2含量.结果 胃癌组织的PGE2含量明显高于癌旁切缘组织,分别为(8.225±2.425)、(1.669±0.287)ng/g,两者差异有统计学意义(P<0.01),低分化和高中分化胃癌组织PGE2含量分别为(9.02±2.28)、(5.38±0.35)ng/g,两者有显著性差异(P<0.05).外周血中PGE2含量与胃癌组织PGE2含量呈正相关(r=0.889,P<0.01).肿瘤直径≥5 cm和<5 cm的胃癌患者外周血中PGE2含量差异有统计学意义(P<0.05).低分化和高中分化胃癌患者外周血中PGE2含量差异也有统计学意义(P<0.05).胃癌组织及外周血中PGE2含量与患者年龄、性别无关,与肿瘤部位、浸润深度、临床病理分期及是否淋巴结转移也无关.结论 胃癌患者肿瘤组织中PGE2含量增高,其外周血PGE2含量也随之增高,表明外周血PGE:水平与胃癌组织释放的PGE2含量成正比.测定外周血中PGE2可以间接评估胃癌患者的肿瘤大小与分化程度. 相似文献