首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   59651篇
  免费   5643篇
  国内免费   4435篇
耳鼻咽喉   488篇
儿科学   759篇
妇产科学   745篇
基础医学   6837篇
口腔科学   1208篇
临床医学   7922篇
内科学   9050篇
皮肤病学   517篇
神经病学   2821篇
特种医学   2109篇
外国民族医学   28篇
外科学   6276篇
综合类   10046篇
现状与发展   15篇
一般理论   6篇
预防医学   4044篇
眼科学   1601篇
药学   6658篇
  37篇
中国医学   3573篇
肿瘤学   4989篇
  2024年   246篇
  2023年   1000篇
  2022年   2559篇
  2021年   3209篇
  2020年   2454篇
  2019年   2054篇
  2018年   2095篇
  2017年   2052篇
  2016年   1839篇
  2015年   2809篇
  2014年   3585篇
  2013年   3175篇
  2012年   4575篇
  2011年   4790篇
  2010年   3242篇
  2009年   2574篇
  2008年   3326篇
  2007年   3137篇
  2006年   3001篇
  2005年   2786篇
  2004年   2020篇
  2003年   1843篇
  2002年   1539篇
  2001年   1256篇
  2000年   1283篇
  1999年   1286篇
  1998年   842篇
  1997年   782篇
  1996年   673篇
  1995年   639篇
  1994年   573篇
  1993年   353篇
  1992年   413篇
  1991年   327篇
  1990年   261篇
  1989年   205篇
  1988年   216篇
  1987年   190篇
  1986年   172篇
  1985年   121篇
  1984年   62篇
  1983年   52篇
  1982年   24篇
  1981年   25篇
  1980年   15篇
  1979年   21篇
  1978年   5篇
  1977年   4篇
  1975年   3篇
  1929年   2篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Vegetation water content (VWC) is the key input parameter for a soil moisture retrieval algorithm based on microwave remote sensing, and VWC uncertainty can limit the estimated accuracy of soil moisture. There has been little research on VWC algorithm development and validation in China, and the uncertainty of the VWC estimation method has not been well evaluated. Therefore, the aim of this study is to evaluate the uncertainty of the VWC estimation method used in the SMAP (Soil Moisture Active Passive) algorithm on three spatial scales (the point-scale, 30 m scale, and 1 km scale) for maize in northeast China. Results from three ground experimental datasets showed that the SMAP VWC estimation method was strongly biased with an average overestimation of 1.16 kg m?2,1.04 kg m?2, and 1.13 kg m?2 for the point-scale, 30 m scale, and 1 km scale respectively, and maximum bias occurred in the mid-stage of maize. Also, a new power relationship between NDVI (Normalized Difference Vegetation Index) and VWC was proposed for the 30 m scale based on Sentinel 2 NDVI and field VWC values from 2017 experiment, with respective R2 (coefficient of determination) and Root Mean Squared Error (RMSE) values of 0.80 and 0.67 kg m?2. The results confirmed that this power relationship was still suitable for VWC estimation at the 1 km scale, and it has smaller bias than the original SMAP VWC method. Future work will be carried out to evaluate the applicability of this VWC estimation method over a lager region. It is expected that it can improve the accuracy of soil moisture by providing high precision VWC input parameters.  相似文献   
2.
3.
Based on the physical randomization of completely randomized experiments, in a recent article in Statistics in Medicine, Rigdon and Hudgens propose two approaches to obtaining exact confidence intervals for the average causal effect on a binary outcome. They construct the first confidence interval by combining, with the Bonferroni adjustment, the prediction sets for treatment effects among treatment and control groups, and the second one by inverting a series of randomization tests. With sample size n, their second approach requires performing O(n4)randomization tests. We demonstrate that the physical randomization also justifies other ways to constructing exact confidence intervals that are more computationally efficient. By exploiting recent advances in hypergeometric confidence intervals and the stochastic order information of randomization tests, we propose approaches that either do not need to invoke Monte Carlo or require performing at most O(n2)randomization tests. We provide technical details and R code in the Supporting Information . Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
4.
Objective: To evaluate the long-term clinical effect of high-intensity focussed ultrasound (HIFU) as a non-invasive modality for ablation of abdominal wall endometriosis (AWE) foci.

Methods: All women who were diagnosed with cutaneous endometriosis and underwent HIFU ablation and 4-year follow-up were included. Patient symptoms, imaging performed, HIFU ablation, recurrence, lesion location, size and number were collected and analyzed.

Results: A total of 51 women with 57 painful abdominal wall masses with a median volume of 4.00?cm3 and a mean age of 30.5±2.12 years were treated with HIFU. The main symptoms were a palpable painful abdominal mass (93%), protrusion of the skin (28.1%, 16) or lack of protrusion of the skin (71.9%, 41). Ultrasound was initially performed in 100% (51) of women, whereas 6% (3) required MRI examinations to distinguish the features and range of the masses. Ablation was performed with a median 300?s of sonication time, 40?min treatment time, 150?W of power and 41800?J of total energy to treat lesions that were a median volume of 3.83?cm3. No severe complications occurred, except in one patient with a first-degree skin burn, during the 48-month follow-up period. The pooled recurrence of cutaneous endometriosis occurred in 3.9% (2) of women.

Conclusion: The diagnosis of AWE should be confirmed with imaging of the lesion number, location, size and features before HIFU ablation. HIFU should be the first choice for the treatment of AWE as it is a non-invasive method, with high efficiency and safety and rapid postoperative recovery.  相似文献   

5.
6.
7.
目的观察关节镜下采用自体腘绳肌腱经胫骨隧道前交叉韧带(anterior cruciate ligament, ACL)双束八股解剖重建的临床效果。方法随访上海交通大学附属第六人民医院运动医学科2018年12月—2020年1月收治的103例ACL断裂患者资料,其中男78例,女25例,年龄18~45岁,平均(26.8±5.86)岁;左侧47例,右侧56例,均采用关节镜下自体腘绳肌腱经胫骨隧道打股骨骨隧道,ACL双束八股解剖重建。按照Lysholm评分、国际膝关节评分委员会(IKDC)膝关节评分、Tegner膝关节评分标准和膝关节自我效能量表K-SES评价疗效。结果所有患者术后获随访12~42个月,平均(24±8.18)个月;手术前、末次随访评分比较,Lysholm评分分别为(48.41±4.44)分和(95.34±1.91)分,2组比较差异有统计学意义(P<0.001);IKDC评分分别为(44.05±4.36)分和(95.66±1.89)分,2组比较差异有统计学意义(P<0.001);Tegner评分分别为(2.84±0.95)分和(6.15±0.89)分,2组比较差异有统计学意义(P<0.001);膝关节自我效能量表K-SES量表(3.10±0.83)分和(7.12±1.10)分,2组比较差异有统计学意义(P<0.001)。末次随访103例患者前抽屉试验阴性,轴移试验阴性。98例(95.1%)Lachman试验阴性,5例(4.9%)Lachman试验1°阳性。结论关节镜下采用自体腘绳肌腱经胫骨隧道双束八股解剖重建前交叉韧带是一种恢复膝关节稳定性,恢复伤前活动水平的有效方法。  相似文献   
8.
9.
Temporomandibular joint osteoarthritis (TMJOA) is a chronic degenerative disease for which the underlying mechanism still remains unclear. Compared with apoptosis and autophagy, necroptosis causes greater harm to tissue homeostasis by releasing damage-associated molecular patterns (DAMPs). However, the role of necroptosis and downstream key DAMPs in TMJOA is unknown. Here, rodent models of TMJOA were established by the unilateral anterior crossbite (UAC). Transmission electron microscopy (TEM) and immunohistochemistry of receptor interacting protein kinase 3 (RIPK3)/phosphorylation of mixed lineage kinase domain-like protein (pMLKL) were conducted to evaluate the occurrence of necroptosis in vivo. The therapeutic effects of blocking necroptosis were achieved by intra-articularly injecting RIPK3 or MLKL inhibitors and using RIPK3 or MLKL knockout mice. In vitro necroptosis of condylar chondrocyte was induced by combination of tumor necrosis factor alpha (TNFα), second mitochondria-derived activator of caspases (SMAC) mimetics and carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]- fluoromethylketone (z-VAD-fmk). The possible DAMPs released by necroptotic chondrocytes were screened by quantitative proteomics and blocked by specific antibody. Translucent cytosol, swollen organelles, and ruptured cell membranes, features of necroptosis, were frequently manifested in chondrocytes at the early stage of condylar cartilage degeneration in TMJOA, which was accompanied by upregulation of RIPK3/pMLKL. Inhibiting or knocking out RIPK3/MLKL significantly prevented cartilage degeneration. DAMPs released by necroptotic condylar chondrocytes, such as syndecan 4 (SDC4) and heat shock protein 90 (HSP90), were verified. Furthermore, blocking the function of SDC4 significantly attenuated the expression of TNFα in cartilage and synovium, and accordingly increased cartilage thickness and reduced synovial inflammation. Thus, the necroptotic vicious cycle of TNFα-SDC4-TNFα contributes to cartilage degeneration and synovitis, and can serve as a potential therapeutic target for treating TMJOA. © 2022 American Society for Bone and Mineral Research (ASBMR).  相似文献   
10.
Background: Previous genome-wide association study (GWAS) has revealed the association between MYP10 at 8p23 and MYP15 at 10q21.1 and high myopia (HM) in a French population. This study is managed to discover the connection between some single nucleotide polymorphism (located at MYP10 and MYP15) and Han Chinese HM.

Methods and Results: This case-control association study contained 1673 samples, including 869 ophthalmic patients and 804 controls. Twelve tag SNPs have been selected from the MYP10 and MYP15 loci and genotyped by SNaPshot method. Among 12 SNPs, rs4840437 and rs6989782 in TNKS gene were found significant association with HM. Carriers of rs4840437G allele and rs4840437GG genotype created a low risk of high myopia (P = .036, OR = 0.81, 95%CI = 0.71–0.93; P = .016, OR = 0.73, 95%CI = 0.56–0.96; respectively). Carriers of rs6989782T allele and rs6989782TT+CT genotype also had a decreased risk of high myopia (P = .048, OR = 0.82, 95%CI = 0.71–0.94; P = .006, OR = 0.74, 95%CI = 0.59–0.92; respectively). Other 10 SNPs displaced nonsignificant association with HM. Additionally, the risk haplotype AC and the protective haplotype GT, generated by two SNPs in TNKS, were considerably more likely to be association with HM (for AC, P = .002 and OR = 1.26; for GT, P = .027 and OR = 0.84).

Conclusions: Our results demonstrated that some heritable variants in the TNKS gene are associated with HM in the Han population. The possible functions of TNKS in the development and pathogenesis of hereditary high myopia still require further researches to identify.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号