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   15457篇
  免费   1233篇
  国内免费   731篇
耳鼻咽喉   128篇
儿科学   148篇
妇产科学   184篇
基础医学   2729篇
口腔科学   1308篇
临床医学   1009篇
内科学   1952篇
皮肤病学   431篇
神经病学   1034篇
特种医学   317篇
外国民族医学   4篇
外科学   1932篇
综合类   2186篇
现状与发展   2篇
预防医学   449篇
眼科学   460篇
药学   1598篇
  3篇
中国医学   581篇
肿瘤学   966篇
  2024年   14篇
  2023年   202篇
  2022年   239篇
  2021年   542篇
  2020年   521篇
  2019年   429篇
  2018年   486篇
  2017年   463篇
  2016年   497篇
  2015年   641篇
  2014年   940篇
  2013年   1207篇
  2012年   888篇
  2011年   1085篇
  2010年   902篇
  2009年   922篇
  2008年   980篇
  2007年   940篇
  2006年   847篇
  2005年   711篇
  2004年   675篇
  2003年   583篇
  2002年   424篇
  2001年   327篇
  2000年   244篇
  1999年   247篇
  1998年   221篇
  1997年   179篇
  1996年   137篇
  1995年   124篇
  1994年   111篇
  1993年   106篇
  1992年   78篇
  1991年   73篇
  1990年   70篇
  1989年   53篇
  1988年   54篇
  1987年   32篇
  1986年   20篇
  1985年   35篇
  1984年   38篇
  1983年   12篇
  1982年   18篇
  1981年   13篇
  1980年   15篇
  1979年   10篇
  1978年   9篇
  1977年   8篇
  1976年   12篇
  1974年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Collagens are the most abundant proteins in the extracellular matrix. They provide a framework to build organs and tissues and give structural support to make them resistant to mechanical load and forces. Several intra‐ and extracellular modifications are needed to make functional collagen molecules, intracellular post‐translational modifications of proline and lysine residues having key roles in this. In this article, we provide a review on the enzymes responsible for the proline and lysine modifications, that is collagen prolyl 4‐hydroxylases, 3‐hydroxylases and lysyl hydroxylases, and discuss their biological functions and involvement in diseases.  相似文献   
2.
3.
4.
《Journal of vascular surgery》2020,71(6):1921-1929
ObjectiveIdentifying biomarkers for abdominal aortic aneurysms (AAA) could prove beneficial in prognosis of AAA and thus the selection for treatment. Microfibrillar-associated protein 4 (MFAP4) is an extracellular matrix protein that is highly expressed in aorta. MFAP4 is involved in several tissue remodeling-related diseases. We aimed to investigate the potential role of plasma MFAP4 (pMFAP4) as a biomarker of AAA.MethodsPlasma samples and data were obtained for 504 male AAA patients and 188 controls in the Viborg Vascular (VIVA) screening trial. The pMFAP4 levels were measured by Alphalisa. The Mann-Whitney U test assessed differences in pMFAP4 levels between the presence and absence of different exposures of interest. The correlation between pMFAP4 and aorta growth rate were investigated through spearman's correlation analysis. Immunohistochemistry and multiple logistic regression adjusted for potential confounders assessed the association between pMFAP4 and AAA. Multiple linear regression assessed the correlation between pMFAP4 and aorta growth rate. Cox regression and competing risk regression were used to investigate the correlation between AAA patients with upper tertile pMFAP4 and the risk of undergoing later surgical repair.ResultsA significant negative correlation between pMFAP4 and aorta growth rate was observed using spearman's correlation analysis (ρ = −0.14; P = .0074). However, this finding did not reach significance when applying multiple linear regression. A tendency of decreased pMFAP4 was observed in AAA using immunohistochemistry. Competing risk regression adjusted for potential confounders indicated that patients with upper tertile pMFAP4 had a hazard ratio of 0.51 (P = .001) for risk of undergoing later surgical repair.ConclusionsHigh levels of pMFAP4 are associated with a decreased likelihood of receiving surgical repair in AAA. This observation warrants confirmation in an independent cohort.  相似文献   
5.
6.
ObjectivesMeshes/matrices are commonly used in immediate breast reconstruction. There are few studies comparing biological and synthetic meshes and it is unknown what type of mesh gives the best long-term results. The aim of this study was to compare long-term health-related quality of life (HrQoL) and patient satisfaction in implant-based immediate breast reconstruction with a biological mesh (Surgisis®) with that of patients reconstructed with a synthetic mesh (TIGR ® Matrix Surgical Mesh).Material and methodsBoth cohorts were prospectively included and consecutively operated. Clinical data was collected. HrQoL was evaluated with EuroQoL-5 dimension – 3 levels questionnaire (EQ-5D-3L) and the Hospital Anxiety and Depression Scale (HADS) and the Breast-Q.Results and conclusionSeventy-one patients were operated on in the biological group and 49 in the synthetic group. The response rates were 75 and 84 per cent, respectively. Mean follow-up time was 74 months and 23 months, respectively. There were no statistical differences in satisfaction and quality of life between the two groups. Complications and radiation seem to lead to a lower satisfaction. Our findings could indicate that biological and synthetic meshes give an equal long-term result as regards patients’ perceived quality of life.  相似文献   
7.
8.
Ovarian carcinoma is one of the most lethal malignancies, but only very few prognostic biomarkers are known. The degradome, comprising proteases, protease non-proteolytic homologues and inhibitors, have been involved in the prognosis of many cancer types, including ovarian carcinoma. The prognostic significance of the whole degradome family has not been specifically studied in high-grade serous ovarian cancer. A targeted DNA microarray known as the CLIP-CHIP microarray was used to identify potential prognostic factors in ten high-grade serous ovarian cancer women who had early recurrence (<1.6 years) or late/no recurrence after first line surgery and chemotherapy. In women with early recurrence, we identified seven upregulated genes (TMPRSS4, MASP1/3, SPC18, PSMB1, IGFBP2, CFI – encoding Complement Factor I – and MMP9) and one down-regulated gene (ADAM-10). Using immunohistochemistry, we evaluated the prognostic effect of these 8 candidate genes in an independent cohort of 112 high-grade serous ovarian cancer women. Outcomes were progression, defined according to CA-125 criteria, and death. Multivariate Cox proportional hazard regression models were done to estimate the associations between each protein and each outcome. High ADAM-10 expression (intensity of 2–3) was associated with a lower risk of progression (adjusted hazard ratio (HR): 0.51; 95% confidence interval (CI): 0.29-0.87). High complement factor I expression (intensity 2–3) was associated with a higher risk of progression (adjusted HR: 2.30, 95% CI: 1.17–4.53) and death (adjusted HR: 3.42; 95% CI: 1.72–6.79). Overall, we identified the prognostic value of two proteases, ADAM-10 and complement factor I, for high-grade serous ovarian cancer which could have clinical significance.  相似文献   
9.
Matrix metalloproteinase-11 (MMP11) is an enzyme with proteolytic activity against matrix and nonmatrix proteins. Although most MMPs are secreted as inactive proenzymes and are later activated extracellularly, MMP11 is activated intracellularly by furin within the constitutive secretory pathway. It is a key factor in physiological tissue remodeling and its alteration may play an important role in the progression of epithelial malignancies and other diseases. TCGA colon and colorectal adenocarcinoma data showed that upregulation of MMP11 expression correlates with tumorigenesis and malignancy. Here, we provide evidence that a germline variant in the MMP11 gene (NM_005940: c.232C>T; p.(Pro78Ser)), identified by whole exome sequencing, can increase the tumorigenic properties of colorectal cancer (CRC) cells. P78S is located in the prodomain region, which is responsible for blocking MMP11's protease activity. This variant was detected in the proband and all the cancer-affected family members analyzed, while it was not detected in healthy relatives. In silico analyses predict that P78S could have an impact on the activation of the enzyme. Furthermore, our in vitro analyses show that the expression of P78S in HCT116 cells increases tumor cell invasion and proliferation. In summary, our results show that this variant could modify the structure of the MMP11 prodomain, producing a premature or uncontrolled activation of the enzyme that may contribute to an early CRC onset in these patients. The study of this gene in other CRC cases will provide further information about its role in CRC development, which might improve patient treatment in the future.  相似文献   
10.
Daily exposure to sunlight is known to affect the structure and function of the epidermal basement membrane (BM), as well as epidermal differentiation and epidermal barrier function. The aim of this study is to clarify whether the inhibition of BM‐degrading enzymes such as heparanase and matrix metalloproteinase 9 (MMP‐9) can improve the epidermal barrier function of facial skin, which is exposed to the sun on a daily basis. 1‐(2‐hydroxyethyl)‐2‐imidazolidinone (HEI) was synthesized as an inhibitor of both heparanase and MMP‐9. HEI inhibited not only the BM damage at the DEJ but also epidermal proliferation, differentiation, water contents and transepidermal water loss abnormalities resulting from ultraviolet B (UVB). This was determined in this study by the use of UVB‐induced human cultured skins as compared with the control without HEI. Moreover, topical application of HEI improved epidermal barrier function by increasing water content and decreasing transepidermal water loss in daily sun‐exposed facial skin as compared with non‐treated skins. These results suggest that the inhibition of both heparanase and MMP‐9 is an effective way to care for regularly sun‐exposed facial skin by protecting the BM from damage.  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