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   6392篇
  免费   495篇
  国内免费   338篇
耳鼻咽喉   126篇
儿科学   122篇
妇产科学   108篇
基础医学   707篇
口腔科学   60篇
临床医学   940篇
内科学   908篇
皮肤病学   34篇
神经病学   484篇
特种医学   194篇
外国民族医学   4篇
外科学   619篇
综合类   748篇
预防医学   458篇
眼科学   180篇
药学   724篇
  1篇
中国医学   239篇
肿瘤学   569篇
  2024年   15篇
  2023年   68篇
  2022年   168篇
  2021年   243篇
  2020年   200篇
  2019年   172篇
  2018年   170篇
  2017年   161篇
  2016年   173篇
  2015年   206篇
  2014年   309篇
  2013年   287篇
  2012年   391篇
  2011年   466篇
  2010年   288篇
  2009年   197篇
  2008年   301篇
  2007年   358篇
  2006年   341篇
  2005年   356篇
  2004年   271篇
  2003年   231篇
  2002年   238篇
  2001年   128篇
  2000年   156篇
  1999年   197篇
  1998年   113篇
  1997年   117篇
  1996年   94篇
  1995年   97篇
  1994年   85篇
  1993年   75篇
  1992年   81篇
  1991年   63篇
  1990年   55篇
  1989年   58篇
  1988年   37篇
  1987年   32篇
  1986年   32篇
  1985年   21篇
  1984年   22篇
  1983年   18篇
  1982年   12篇
  1981年   9篇
  1980年   13篇
  1979年   15篇
  1978年   10篇
  1977年   9篇
  1973年   6篇
  1965年   8篇
排序方式: 共有7225条查询结果,搜索用时 15 毫秒
21.
22.
目的 :探讨MMP 2、TIMP 2、Ki 67表达与库肯勃氏瘤病理生物学行为的关系。方法 :采用免疫组化SP法对 32例库肯勃氏瘤组织和 10例正常卵巢组织进行MMP 2、TIMP 2和Ki 67表达的检测。结果 :MMP 2、TIMP 2、Ki 67在库肯勃氏瘤组织中的表达量显著高于正常卵巢组织 (P <0 .0 1)。有合并转移的库肯勃氏瘤中MMP 2、Ki 67高于无合并转移者 (P <0 .0 5 ) ,TIMP 2低于无合并转移者 (P <0 .0 5 )。MMP 2、Ki 67与术后生存时间呈负相关 (P <0 .0 1) ,TIMP 2与术后生存时间呈正相关 (P <0 .0 1)。结论 :MMP 2、TIMP 2、Ki 67在库肯勃氏瘤发生、发展中起重要作用 ,可作为判断卵巢转移癌恶性程度、临床分期和评估预后的临床参考指标  相似文献   
23.
Polycystic ovary syndrome (PCOS) is associated with low-grade chronic inflammation.This was a retrospective case–control study.In the present study, the risk coefficients of neutrophil to lymphocyte ratio (NLR), high-sensitive C-reactive protein (hs-CRP), and mean platelet volume (MPV) in obese patients with PCOS were determined. This study was designed to investigate NLR, hs-CRP, and MPV levels in 68 obese patients with PCOS and 44 nonobese patients with PCOS, and our study group was matched with 47 obese and 43 nonobese controls, respectively.PCOS group had higher MPV, NLR, insulin, glucose, and HOMA-IR rates than those of the controls. Subgroup analyses revealed that the obese PCOS group had higher NLR, hs-CRP, and MPV levels compared to those of controls. The obese PCOS group had higher NLR, hs-CRP, and MPV levels compared to those of the nonobese PCOS group. The odds ratios and 95% confidence intervals of those variables (NLR, hs-CRP, MPV) were found significant (P < .05). NLR, hs-CRP, and MPV variables were found statistically significant in the analysis of receiver operating characteristics.Our study demonstrated that NLR, hs-CRP, and MPV levels are increased in patients with obese PCOS.  相似文献   
24.
Background:Osteoarthritis is a common degenerative disease with a high incidence, high disability rate, and poor prognosis. Clinical studies have shown that Bushen Huoxue formula can relieve joint swelling and pain and improve limb function and joint mobility, but there is a lack of high-quality scientific basis. Using network pharmacology and molecular docking technology to study the mechanism of Bushen Huoxue formula in the treatment of osteoarthritis.Methods:First, the active ingredients and corresponding target predictions of the formula were obtained through the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and the China National Knowledge Infrastructure. Meanwhile, the osteoarthritis disease targets were obtained through the genome annotation database platform (GeneCards) and the DrugBank database, and the target proteins obtained above were standardized using the Uniprot (https://www.uniprot.org) database standardization of names. Then, the Venn diagram was created by taking the intersection of the active ingredient and the target of the disease, and the “active ingredient-target” network was constructed and analyzed using Cytoscape 3.7.2 software. At the same time, the intersecting targets were imported into the Search Tool for the Retrieval of Interaction Gene/Proteins database to build a protein-protein interaction network and to screen the core targets; the intersecting targets were visualized by using the Database for Annotation, Visualization and Integrated Discovery 6.8 database for gene ontology functional analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and construct the “active ingredient-target-pathway” network. Finally, the main active ingredients of the formula for tonifying the kidney and invigorating the blood were validated by molecular docking with the core targets.Results:A total of 194 active ingredients and 365 targets of the Bushen Huoxue formula were collected, 776 targets for osteoarthritis diseases and 96 targets for the intersection of active ingredients and diseases. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis yielded 104 relevant pathways, including tumor necrosis factor signaling pathways, cancer signaling pathways, nucleotide-binding oligomerization domain-like receptor signaling pathways, Toll-like receptors signaling pathways, and osteoclast differentiation, apoptosis, T-cell receptor signaling pathway, and other related pathways. The molecular docking results showed good binding of the main active ingredients to the core targets.Conclusion:This study shows that the treatment of osteoarthritis involves multicomponent, multitarget, and multipathway processes. The mechanism of anti-inflammatory, antioxidant, inhibition of cartilage matrix degradation, and reduction of subchondral bone destruction may be an important mechanism for the therapeutic effect.  相似文献   
25.
Solid epoxy resin is highly desired in adhesives, electronic materials and coatings due to the attractive characteristics of solvent-free, highly efficient utilization and convenient storage and transportation. However, the challenges remain in fabricating high-toughness solid epoxy resin through a facile and efficient way. Here, a high-performance environment-friendly solid epoxy resin was fabricated by employing maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH) as the flexibilizer via one-step banburying method. The results showed that the modified epoxy resin maintained a high glass transition temperature (Tg) and thermal stability, while its impact strength, tensile toughness and flexural toughness were significantly increased compared with the neat epoxy resin. The impact strength, tensile toughness and flexural toughness of R-EM10 are improved 138%, 195% and 149%, respectively. The EVA-g-MAH was introduced in the epoxy matrix as a separate phase to increase toughness via transfer stress and dissipated energy. The attractive properties of this facile fabrication process and the high-toughness, as well as the environment-friendly performance make this solid epoxy highly promising for large-scale industrial application.

High-toughness and environment-friendly solvent free solid epoxy resin through a low-cost, facile and large-scale fabrication process.  相似文献   
26.
ObjectiveTo describe our experience with the combined use of pedicled neurotrophic flap and distraction osteogenesis in the management of complex lower extremity injuries with composite bone and soft tissue defects and assess the functional and cosmetic results of this method.MethodsA pedicled flap with a marked perforator artery was applied for soft tissue coverage after radical debridement and temporary external fixation. In the second stage, the Ilizarov external fixator was used in place of the temporary external fixator for reconstruction of the segmental bone defect by distraction osteogenesis. Twenty‐five patients (16 men and nine women; mean age, 39.2 years) were treated by using this combined technique between 2008 and 2016. All cases were graded initially as Gustilo–Anderson grade IIIB open fractures. The soft tissue defect after radical debridement ranged from 9 cm × 5 cm to 14 cm × 11 cm, and the average size of segmental defect was 5.2 (Range, 2.5–8.5) cm. Seventeen of these patients had a history of local infection. The bone structure and function were evaluated by two independent evaluators using Paley''s criteria.ResultsTwenty‐five patients were followed up for an average of 28.96 (Range, 15–48) months. The distally based sural neurovascular flap was applied in 13 patients, and the greater saphenous neurocutaneous perforator flap in 12 patients. The flap area ranged from 10 cm × 5 cm to 14 cm × 12 cm. Sufficient coverage of soft tissue defect was achieved in all cases. All flaps survived completely without complications. The bone defects were corrected by a mean lengthening of 6.94 (Range, 4.5–9.5) cm. The residual discrepancy was <1 cm in all cases, which was not clinically significant. The function was evaluated as excellent in 12 patients and good in 13 patients. Bone results were graded as excellent in 18 patients and good in seven patients. Complications during treatment included pain, pin tract infections, ankle midfoot joint stiffness, and docking site nonunion. No recurrence of infection was observed in infected patients. All cases achieved successful limb salvage and satisfactory function recovery without recurrence of infection.ConclusionsThe combined technique of a perforator artery pedicled neurotrophic flap and distraction osteogenesis is an effective alternative approach in the salvage treatment of massively traumatized and chronically infected lower extremities.  相似文献   
27.
The tremendous development of peptide-based cancer vaccine has attracted incremental interest as a powerful approach in cancer management, prevention and treatment. As successful as tumor vaccine has been, major challenges associated with achieving efficient immune response against cancer are (1) drainage to and retention in lymph nodes; (2) uptake by dendritic cells (DCs); (3) activation of DCs. In order to overcome these barriers, here we construct PBE-modified TRP2 nanovaccine, which comprises TRP2 peptide tumor antigen and diblock copolymer PEG-b-PAsp grafted with phenylboronic ester (PBE). We confirmed that this TRP2 nanovaccine can be effectively trapped into lymph node, uptake by dendritic cells and induce DC maturation, relying on increased negative charge, ROS response and pH response. Consistently, this vehicle loaded with TRP2 peptide could boost the strongest T cell immune response against melanoma in vivo and potentiate antitumor efficacy both in tumor prevention and tumor treatment without any exogenous adjuvant. Furthermore, the TRP2 nanovaccine can suppress the tumor growth and prolong animal survival time, which may result from its synergistic effect of inhibiting tumor immunosuppression and increasing cytotoxic lymphocyte (CTL) response. Hence this type of PBE-modified nanovaccine would be widely used as a simple, safe and robust platform to deliver other antigen in cancer immunotherapy.  相似文献   
28.
Visual attention can be allocated to locations or objects, leading to enhanced processing of information at the specific location (space-based effects) or specific object (object-based effects). Previous studies have observed object-based effects to be smaller and less robust than space-based effects, with large individual differences in their temporal occurrence. Studies on space- and object-based effects are often based on a two-rectangle paradigm in which targets appear at cued locations more often than uncued locations. It is, however, unclear whether and how the target''s spatial probability affects the temporal occurrence of these effects. In three experiments with different cue validities (80%, 50% and 33%), we systematically changed the interval between the cue and the target from 50 to 600 ms. On a group level and for individuals, we examined how cue validity affects the occurrence of object- and space-based effects. We observed that the magnitude and the prevalence of space-based effects heavily decreased with reduced cue validity. Object-based effects became even more sparse and turned increasingly negative with decreasing cue validity, representing a different-object rather than a same-object advantage. These findings indicate that changes in cue-validity affect both space- and object-based effects, but it does not account for the low prevalence and magnitude of object-based effects.  相似文献   
29.
The cable-stayed suspension bridge is one type of bridge that has been increasingly applied to bridge engineering, especially in cross-sea projects. However, the complex combined system of this type of bridge makes it quite difficult for researchers to make a quick decision of the parameter values during the design stage. The Hellinger–Reissner method is applied here to analyze the deformation and force of the structural members in the bridge. The advantage of this method is that the solving of deformation and force is independent of each other, which would enhance the accuracy of the final results. Different load conditions are also considered in the analysis. The results from the present method are compared with test results and finite element analysis, and show good agreements. It implies that the Hellinger–Reissner is a comparatively more efficient method to help designers choose the key parameters for cable-stayed suspension bridges.  相似文献   
30.
目的:建立血浆中 B Z类失能剂的高效液相二极管矩阵检测分析方法,为 B Z类失能剂中毒病人的临床诊断提供分析手段。方法:采用 Sep Pak C18 柱固相提取,乙酸乙酯洗脱, Resolve C18 反相柱分离,0.12% 三氟乙酸( T F A)的 50% 甲醇溶液梯度洗脱,二极管矩阵检测器( D A D) 三波长(220±4)nm ,(254±4)nm ,(300±4)nm 检测。结果:血浆中 H P L C D A D 法检测 4 种失能剂的线性范围为 0.1~1.2 μg,回收率为62.76% ~92.20% ,标准偏差为 3.46% ~11.84% ,最低检出限为 100~400 ng。流动相中 T F A 和甲醇浓度及梯度洗脱是影响分离效果和色谱峰形的主要因素。结论:本文为临床诊断提供简便、快速、灵敏的检测方法,血浆蛋白不干扰测定。4 种失能剂在血浆中采用 H P L C D A D 法同时分离测定目前未见报道。  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