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   2664篇
  免费   183篇
  国内免费   18篇
耳鼻咽喉   21篇
儿科学   144篇
妇产科学   71篇
基础医学   393篇
口腔科学   91篇
临床医学   240篇
内科学   604篇
皮肤病学   52篇
神经病学   200篇
特种医学   67篇
外科学   298篇
综合类   36篇
一般理论   2篇
预防医学   151篇
眼科学   112篇
药学   166篇
中国医学   13篇
肿瘤学   204篇
  2024年   4篇
  2023年   56篇
  2022年   81篇
  2021年   150篇
  2020年   96篇
  2019年   125篇
  2018年   148篇
  2017年   118篇
  2016年   112篇
  2015年   87篇
  2014年   131篇
  2013年   175篇
  2012年   263篇
  2011年   223篇
  2010年   148篇
  2009年   89篇
  2008年   164篇
  2007年   151篇
  2006年   121篇
  2005年   95篇
  2004年   105篇
  2003年   72篇
  2002年   63篇
  2001年   9篇
  2000年   14篇
  1999年   13篇
  1998年   14篇
  1997年   6篇
  1996年   7篇
  1995年   7篇
  1994年   4篇
  1993年   2篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
  1979年   1篇
  1978年   2篇
  1976年   2篇
  1974年   1篇
排序方式: 共有2865条查询结果,搜索用时 15 毫秒
51.
Treatment of metastatic liver disease is at the crossroads of an evolutionary transformation with more and more reports reiterating the benefits of resectional therapy in various cancers. A quest for application of laparoscopic approaches to the management of liver metastasis has arisen due to the projected benefits of less morbidity, early recovery, and equivalent oncological outcome in selected malignancies. However, the diverse and heterogenous data on indications, operative technique, and outcome evaluation make a comparative analysis of these studies difficult. This review is an appraisal of technique and outcome of minimally invasive liver resection as reported in the current literature with special reference to treatment of metastatic colorectal cancers.  相似文献   
52.
Congenital arterioportal fistulae in the liver are rare malformations which can lead to portal hypertension. We report a hepatic arterioportal fistula in a neonate who presented with intestinal hypoperfusion. Computerised tomography angiography showed a fistulous communication between the left hepatic artery and portal vein with hypoperfusion of small and large bowel. A formal left hepatectomy was done followed by clinical improvement and reduction in portal venous pressures. The case and the literature pertaining to it are discussed.  相似文献   
53.
54.
A series of 2,4-aryl-4-((arylsulfonyl)methyl)-4H-benzo[d][1,3]oxazines in good to excellent yields have directly been obtained from N-(2-vinylphenyl)amides and thiols by employing a mixture of K2S2O8-activated charcoal in aqueous acetonitrile solution at 50 °C. A plausible mechanism for the reaction is reported. It reveals that the reaction follows a radical pathway and the persulfate has been the oxygen source for formation of the sulfone group in the products. It is worth mentioning that this protocol utilizes an easily accessible K2S2O8-activated charcoal mixture and thiols, respectively, as an oxidant and sulfonylating precursors for the first time.

A simple method for the synthesis of 2,4-aryl-4-((arylsulfonyl)methyl)-4H-benzo[d][1,3]oxazines using an easily accessible K2S2O8-activated charcoal mixture and thiols, respectively, as an oxidant and sulfonylating precursors has been described.  相似文献   
55.
56.
Objective: To compare the antioxidant and anti-genotoxic properties of Alpinia (A.) galanga, Curcuma (C.) amada, and C. caesia. Methods: Cytotoxicity of ethanol...  相似文献   
57.
Purpose:To assess the retinal manifestations of Parkinson’s disease using optical coherence tomography.Methods:A prospective case-control study comparing 30 eyes from 15 patients with Parkinson’s disease and 22 eyes from 11 healthy age-matched controls. Total macular subfield thickness and the thickness of the ganglion cell layer, nerve fiber layer, and peripapillary retinal nerve fiber layer were measured with spectral-domain optical coherence tomography (SD-OCT).Results:The mean age of PD patients was 68.4 years ± 10.64 (range: 46–82) and in the control group was 66.36 ± 5.22 (range: 64–68). The average disease duration in patients with PD was 6.7 ± 2.8 years (range: 2–10 years). The mean best-corrected visual acuity in PD was 20/26 and 20/20 in controls, with P = 0.0059, which was significant. Significant difference was also found in the contrast sensitivity between both groups. Structural differences in the central macular thickness (P = 0.0001), subfield thicknesses in the superior (P = 0.003), inferior (P = 0.001), nasal (P = 0.004), and temporal subfields (P = 0.017) was seen. Severe thinning of the ganglion cell layer was seen in PD patients (P = 0.000) as well as of the nerve fiber layer (P = 0.004). Peripapillary retinal nerve fiber thickness measured showed significant thinning in superotemporal (P = 0.000), superonasal (P = 0.04), inferonasal (P = 0.000), inferotemporal (P = 0.000), nasal (P = 0.000), and temporal quadrants (P = 0.000).Conclusion:Visual dysfunction was observed in patients with PD along with structural alterations on OCT, which included macular volumes, ganglion cell layer, and peripapillary retinal nerve fiber layer.  相似文献   
58.
Background: Adverse childhood experiences are significant risk factors for physical and mental illnesses in adulthood. Traumatic brain injury/concussion is a challenging condition where pre-injury factors may affect recovery. The association between childhood adversity and traumatic brain injury/concussion has not been previously reviewed. The research question addressed is: What is known from the existing literature about the association between adverse childhood experiences and traumatic brain injury/concussion in adults?

Methods: All original studies of any type published in English since 2007 on adverse childhood experiences and traumatic brain injury/concussion outcomes were included. The literature search was conducted in multiple electronic databases. Arksey and O’Malley and Levac et al.’s scoping review frameworks were used. Two reviewers independently completed screening and data abstraction.

Results: The review yielded six observational studies. Included studies were limited to incarcerated or homeless samples, and individuals at high-risk of or with mental illnesses. Across studies, methods for childhood adversity and traumatic brain injury/concussion assessment were heterogeneous.

Discussion: A positive association between adverse childhood experiences and traumatic brain injury occurrence was identified. The review highlights the importance of screening and treatment of adverse childhood experiences. Future research should extend to the general population and implications on injury recovery.
  • Implications for rehabilitation
  • Exposure to adverse childhood experiences is associated with increased risk of traumatic brain injury.

  • Specific types of adverse childhood experiences associated with risk of traumatic brain injury include childhood physical abuse, psychological abuse, household member incarceration, and household member drug abuse.

  • Clinicians and researchers should inquire about adverse childhood experiences in all people with traumatic brain injury as pre-injury health conditions can affect recovery.

  相似文献   
59.
Arthrogryposis multiplex congenita affects approximately 1 in 3,000 individuals of different ethnic backgrounds and displays an equal incidence in males and females. The underlying mechanism for congenital contracture of the joints is decreased fetal movement during intrauterine development. This disorder is associated with over 400 medical conditions and 350 known genes that display considerable variability in phenotypic expression. In this report, four fetal or perinatal autopsy cases of arthrogryposis were studied by gross morphology, microscopic histopathologic examination, and whole genome sequencing of postmortem DNA. Two stillborn sibling fetuses with arthrogryposis, pterygia, and amyoplasia had compound heterozygous pathogenic variants in NEB. A neonate with a histopathologic diagnosis of nemaline myopathy had a heterozygous de novo pathogenic variant in ACTA1. Another stillborn infant with pterygia and arthrogryposis had a heterozygous de novo likely pathogenic variant in BICD2. These cases demonstrate the utility of whole genome sequencing as the principal diagnostic method of lethal forms of skeletal muscle disorders that present with arthrogryposis and muscle amyoplasia/hypoplasia. Molecular diagnosis provides an opportunity for studying patterns of inheritance and for family counseling concerning future pregnancies.
  相似文献   
60.
Studies were conducted with extracts of several varieties of tobacco in search of neuronal nitric oxide synthase (nNOS) inhibitors which may be of value in the treatment of stroke. Current therapies do not directly exploit modulation of nNOS activity due to poor selectivity of the currently available nNOS inhibitors. The properties of a potentially novel nNOS inhibitor(s) derived from tobacco extracts, and the concentration‐dependent, modulatory effects of the tobacco‐derived naphthoquinone compound, 2,3,6‐trimethyl‐1,4‐naphthoquinone (TMN), on nNOS activity were investigated, using 2‐methyl‐1,4‐naphthoquinone (menadione) as a control. Up to 31 µM, both TMN and menadione stimulated nNOS‐catalysed l ‐citrulline production. However, at higher concentrations of TMN (62.5–500 µM), the stimulation was lost in a concentration‐dependent manner. With TMN, the loss of stimulation did not decrease beyond the control activity. With menadione (62.5–500 µM), the loss of stimulation surpassed that of the control (78 ± 0.01% of control activity), indicating a true inhibition of nNOS activity. This study suggests that potential nNOS inhibitors are present in tobacco, most of which remain to be identified. Copyright © 2009 John Wiley & Sons, Ltd.  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