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   8060篇
  免费   432篇
  国内免费   74篇
耳鼻咽喉   53篇
儿科学   174篇
妇产科学   657篇
基础医学   912篇
口腔科学   121篇
临床医学   906篇
内科学   1665篇
皮肤病学   80篇
神经病学   536篇
特种医学   242篇
外科学   1065篇
综合类   178篇
预防医学   422篇
眼科学   72篇
药学   591篇
中国医学   117篇
肿瘤学   775篇
  2023年   38篇
  2022年   98篇
  2021年   181篇
  2020年   93篇
  2019年   146篇
  2018年   247篇
  2017年   168篇
  2016年   157篇
  2015年   212篇
  2014年   244篇
  2013年   391篇
  2012年   587篇
  2011年   596篇
  2010年   380篇
  2009年   315篇
  2008年   505篇
  2007年   551篇
  2006年   542篇
  2005年   445篇
  2004年   384篇
  2003年   321篇
  2002年   313篇
  2001年   262篇
  2000年   271篇
  1999年   201篇
  1998年   53篇
  1997年   55篇
  1996年   57篇
  1995年   31篇
  1994年   44篇
  1993年   25篇
  1992年   128篇
  1991年   91篇
  1990年   67篇
  1989年   42篇
  1988年   46篇
  1987年   44篇
  1986年   44篇
  1985年   27篇
  1984年   34篇
  1983年   11篇
  1982年   7篇
  1981年   13篇
  1980年   6篇
  1979年   15篇
  1977年   6篇
  1976年   5篇
  1973年   7篇
  1972年   7篇
  1971年   10篇
排序方式: 共有8566条查询结果,搜索用时 15 毫秒
101.
Most perianal abscesses originate from infected anal glands at the base of the anal crypts. Most abscesses below are usually drained through perianal incision and can be treated successfully. However, when perianal abscesses extend to the high intrapelvic cavity, it may be inadequate treatment through a single route incision through a perianal approach. The aim of this technical note is to show that combined anterior ilioinguinal and perianal incisions may provide optimal surgical field and multiple drainages. Here, we report a 56-year-old male patient with perianal-originating parapsoas abscesses. Residual abscess still remained after initial perianal incision and drainage after 1-month treatment. We presented combined anterior ilioinguinal and perianal incision technique methods for proper drainage in this complicated case. No recurrent or residual abscess remained after 2 weeks of operation. So, combined anterior ilioinguinal incision is feasible for high-located perianal abscess.  相似文献   
102.
103.
PurposePlacental weight has been associated with mammographic pattern and coronary heart disease in the adult offspring, but the mechanisms are unknown. We evaluated the associations of maternal and cord blood hormones with placental weight in normal pregnancies.MethodsProspective study of 167 normal singleton pregnancies in Boston, USA and 256 in Shanghai, China. Maternal hormone levels at the 27th gestational week were available for all pregnancies. Cord blood measurements were available for 86 pregnancies in Boston and 104 in Shanghai. Pearson partial correlation coefficients of log-transformed hormone levels with placental weight were calculated.ResultsMaternal levels of estriol, testosterone, and progesterone (P < .05) were positively associated with placental weight. There was no such evidence for adiponectin, prolactin, and insulin-like growth factor (IGF)-I. Cord blood steroids tended to be inversely associated with placental weight, the results being statistically significant for testosterone (P < .05). There was a marginally significant positive association of cord blood IGF-I with placental weight. Reported results were adjusted for study center.ConclusionsPlacental weight appears to be positively correlated with maternal steroids. Its correlation with cord blood steroids, however, appears inverse, compatible with negative feedback mechanisms. There is also a suggestion for placental weight to be positively associated with cord blood IGF-I.  相似文献   
104.
105.
106.
107.
Purpose.?This study aims to establish an electronic wheelchair system in Taiwan that conforms to multiple master–multiple slave (M3S) standards. The proposed system could enhance the safety and convenience of people with disabilities.

Material and method.?The M3S-based head-controlled electric wheelchair consists of three parts: (A) the input device, (B) the output device, and (C) the safety device. Head movement can be used as the input control to cause the tilting device to produce a corresponding level of analog voltage (backward & forward/left & right) which is then transmitted to the analogy/digital conversion module to control the output device (wheelchair's motor). Ten subjects with C5 uncompleted spinal cord injury were recruited in the clinical assessment. They were randomly assigned into groups A and B. In the group A, the subjects were assigned to operate the head-controlled wheelchair system with M3S standard before operating the head-controlled wheelchair system without M3S standard. In the group B, the subjects were assigned to operate the head-controlled wheelchair system without M3S standard before operating the head-controlled wheelchair system with M3S standard. Two subjects in the group B drop off due to their personal reasons.

Results.?The time cost for group A in completing tasks 1, 2, and 3 with the M3S and without the M3S were insignificant (p > 0.05). The time cost for completing in group B was insignificant (p > 0.05). Thus, the wheelchair operating time is depended on the proficiency of the subjects, not the M3S standard added.

Discussions and conclusions.?The time cost for subjects to operate the wheelchair was determined by their proficiency, not the M3S standard control added to the system. However, the M3S-based system did realize the safety mechanism and complex auxiliary tools with and without the plug-in and play function.  相似文献   
108.
Progression through the mammalian cell cycle is regulated by cyclins, cyclin- dependent kinases (CDKs), and cyclin-dependent kinase inhibitors (CKIs). The function of these proteins in the irreversible growth arrest associated with terminally differentiated cells is largely unknown. The function of Cip/Kip proteins p21(Cip1) and p27(Kip1) during erythropoietin-induced terminal differentiation of primary erythroblasts isolated from the spleens of mice infected with the anemia-inducing strain of Friend virus was investigated. Both p21(Cip1) and p27(Kip1) proteins were induced during erythroid differentiation, but only p27(Kip1) associated with the principal G(1) CDKs-cdk4, cdk6, and cdk2. The kinetics of binding of p27(Kip1) to CDK complexes was distinct in that p27(Kip1) associated primarily with cdk4 (and, to a lesser extent, cdk6) early in differentiation, followed by subsequent association with cdk2. Binding of p27(Kip1) to cdk4 had no apparent inhibitory effect on cdk4 kinase activity, whereas inhibition of cdk2 kinase activity was associated with p27(Kip1) binding, accumulation of hypo-phosphorylated retinoblastoma protein, and G(1) growth arrest. Inhibition of cdk4 kinase activity late in differentiation resulted from events other than p27(Kip1) binding or loss of cyclin D from the complex. The data demonstrate that p27(Kip1) differentially regulates the activity of cdk4 and cdk2 during terminal erythroid differentiation and suggests a switching mechanism whereby cdk4 functions to sequester p27(Kip1) until a specified time in differentiation when cdk2 kinase activity is targeted by p27(Kip1) to elicit G(1) growth arrest. Further, the data imply that p21(Cip1) may have a function independent of growth arrest during erythroid differentiation. (Blood. 2000;96:2746-2754)  相似文献   
109.
Introduction: Epigenetic mechanisms of gene regulatory control play fundamental roles in developmental morphogenesis, and, as more recently appreciated, are heavily implicated in the onset and progression of neoplastic disease, including cancer. Many epigenetic mechanisms are therapeutically targetable, providing additional incentive for understanding of their contribution to cancer and other types of neoplasia.

Areas covered: The Jumonji-domain histone demethylase (JHDM) family exemplifies many of the above traits. This review summarizes the current state of knowledge of the functions and pharmacologic targeting of JHDMs in cancer and other neoplastic processes, with an emphasis on diseases affecting the pediatric population.

Expert opinion: To date, the JHDM family has largely been studied in the context of normal development and adult cancers. In contrast, comparatively few studies have addressed JHDM biology in cancer and other neoplastic diseases of childhood, especially solid (non-hematopoietic) neoplasms. Encouragingly, the few available examples support important roles for JHDMs in pediatric neoplasia, as well as potential roles for JHDM pharmacologic inhibition in disease management. Further investigations of JHDMs in cancer and other types of neoplasia of childhood can be expected to both enlighten disease biology and inform new approaches to improve disease outcomes.  相似文献   

110.
Background: Inhibition of acetylcholinesterase (AChE), a biomarker of organophosphorous and carbamate exposure in environmental and occupational human health, has been commonly used to identify potential safety liabilities. So far, many environmental chemicals, including drug candidates, food additives, and industrial chemicals, have not been thoroughly evaluated for their inhibitory effects on AChE activity. AChE inhibitors can have therapeutic applications (e.g., tacrine and donepezil) or neurotoxic consequences (e.g., insecticides and nerve agents).Objectives: The objective of the current study was to identify environmental chemicals that inhibit AChE activity using in vitro and in silico models.Methods: To identify AChE inhibitors rapidly and efficiently, we have screened the Toxicology in the 21st Century (Tox21) 10K compound library in a quantitative high-throughput screening (qHTS) platform by using the homogenous cell-based AChE inhibition assay and enzyme-based AChE inhibition assays (with or without microsomes). AChE inhibitors identified from the primary screening were further tested in monolayer or spheroid formed by SH-SY5Y and neural stem cell models. The inhibition and binding modes of these identified compounds were studied with time-dependent enzyme-based AChE inhibition assay and molecular docking, respectively.Results: A group of known AChE inhibitors, such as donepezil, ambenonium dichloride, and tacrine hydrochloride, as well as many previously unreported AChE inhibitors, such as chelerythrine chloride and cilostazol, were identified in this study. Many of these compounds, such as pyrazophos, phosalone, and triazophos, needed metabolic activation. This study identified both reversible (e.g., donepezil and tacrine) and irreversible inhibitors (e.g., chlorpyrifos and bromophos-ethyl). Molecular docking analyses were performed to explain the relative inhibitory potency of selected compounds.Conclusions: Our tiered qHTS approach allowed us to generate a robust and reliable data set to evaluate large sets of environmental compounds for their AChE inhibitory activity. https://doi.org/10.1289/EHP6993  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