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   38028篇
  免费   2211篇
  国内免费   205篇
耳鼻咽喉   459篇
儿科学   1180篇
妇产科学   1028篇
基础医学   3813篇
口腔科学   1247篇
临床医学   3337篇
内科学   8181篇
皮肤病学   681篇
神经病学   2250篇
特种医学   1375篇
外国民族医学   4篇
外科学   6917篇
综合类   865篇
现状与发展   3篇
一般理论   27篇
预防医学   2555篇
眼科学   1370篇
药学   2932篇
  1篇
中国医学   274篇
肿瘤学   1945篇
  2024年   42篇
  2023年   427篇
  2022年   1078篇
  2021年   1679篇
  2020年   1014篇
  2019年   1294篇
  2018年   1605篇
  2017年   1160篇
  2016年   1277篇
  2015年   1369篇
  2014年   1729篇
  2013年   2113篇
  2012年   3167篇
  2011年   3064篇
  2010年   1722篇
  2009年   1491篇
  2008年   2277篇
  2007年   2347篇
  2006年   2055篇
  2005年   1809篇
  2004年   1652篇
  2003年   1377篇
  2002年   1197篇
  2001年   381篇
  2000年   327篇
  1999年   296篇
  1998年   201篇
  1997年   134篇
  1996年   144篇
  1995年   110篇
  1994年   98篇
  1993年   77篇
  1992年   150篇
  1991年   167篇
  1990年   132篇
  1989年   131篇
  1988年   114篇
  1987年   111篇
  1986年   96篇
  1985年   123篇
  1984年   81篇
  1983年   55篇
  1982年   58篇
  1981年   57篇
  1980年   42篇
  1979年   52篇
  1978年   41篇
  1975年   36篇
  1974年   36篇
  1973年   37篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
963.
The coronavirus disease 2019 (COVID-19) pandemic has now affected more than 5 million people globally. Typical symptoms include fever, cough, and shortness of breath. Patients with underlying medical comorbidities such as cardiovascular disease and diabetes are more likely to become severely ill. To date there is limited information on how COVID-19 affects patients with a history migraine. Here, we present the cases of 2 women with a history of migraine whose first symptom of COVID-19 was a severe persistent headache.  相似文献   
964.
Left atrial (LA) invasion by lung cancer via hematogenous pathways is relatively uncommon. Herein we report the case of a 68-year-old male without any medical history, in whom lung cancer was diagnosed by transesophageal echocardiographic detection of the LA and left ventricle tumoral invasion via the left upper pulmonary vein. The primary source of tumor was found out by computed tomography.  相似文献   
965.
Trichophyton interdigitale is the second most frequent cause of superficial fungal infections of various parts of the human body. Studying the population structure and genotype differentiation of T. interdigitale strains may lead to significant improvements in clinical practice. The present study aimed to develop and select suitable variable-number tandem-repeat (VNTR) markers for 92 clinical strains of T. interdigitale. On the basis of an analysis of four VNTR markers, four to eight distinct alleles were detected for each marker. The marker with the highest discriminatory power had eight alleles and a D value of 0.802. The combination of all four markers yielded a D value of 0.969 with 29 distinct multilocus genotypes. VNTR typing revealed the genetic diversity of the strains, identifying three populations according to their colonization sites. A correlation between phenotypic characteristics and multilocus genotypes was observed. Seven patients harbored T. interdigitale strains with different genotypes. Typing of clinical T. interdigitale samples by VNTR markers displayed excellent discriminatory power and 100% reproducibility.  相似文献   
966.
Neisseria meningitidis is one of the major causes of meningitis in children and adolescents, but it is rarely found during the neonatal period. Here, we describe a neonate with meningococcal sepsis who was admitted to the hospital on postnatal day 10, and we discuss the clinical features of neonatal infection with N. meningitidis in relation to the literature (analysis of a 97-year period).  相似文献   
967.
This study investigated whether or not the anesthetic effect of ketamine in rats is dependent on adrenal gland hormones. The study was performed on two main rat groups, intact and adrenalectomized. Rat were divided into subgroups and given appropriate doses of ketamine, metyrapone or metyrosine. Durations of anesthesia in the groups were then recorded. Endogenous catecholamine levels were measured in samples taken from peripheral blood. This experimental results showed that ketamine did not induce anesthesia in intact rats at doses of 15 or 30 mg/kg, and that at 60 mg/kg anesthesia was established for only 11 min. However, ketamine induced significant anesthesia even at a dose of 30 mg/kg in animals in which production of endogenous catecholamine (adrenalin, noradrenalin dopamine) was inhibited with metyrosine at a level of 45–47%. Ketamine at 60 mg/kg in animals in which endogenous catecholamine was inhibited at a level of 45–47% established anesthesia for 47.6 min. However, ketamine at 30 and 60 mg/kg induced longer anesthesia in adrenalectomized rats with higher noradrenalin and dopamine levels but suppressed adrenalin production. Adrenalin plays an important role in the control of duration of ketamine anesthesia, while noradrenalin, dopamine and corticosterone have no such function. If endogenous adrenalin is suppressed, ketamine can even provide sufficient anesthesia at a 2-fold lower dose. This makes it possible for ketamine to be used in lengthy surgical procedures.  相似文献   
968.
Several attenuated and non-pathogenic bacterial species have been demonstrated to actively target diseased sites and successfully deliver plasmid DNA, proteins and other therapeutic agents into mammalian cells. These disease-targeting bacteria can be employed for targeted delivery of therapeutic and imaging cargos in the form of a bio-hybrid system. The bio-hybrid drug delivery system constructed here is comprised of motile Escherichia coli MG1655 bacteria and elliptical disk-shaped polymeric microparticles. The transport direction for these vehicles can be controlled through biased random walk of the attached bacteria in presence of chemoattractant gradients in a process known as chemotaxis. In this work, we utilize a diffusion-based microfluidic platform to establish steady linear concentration gradients of a chemoattractant and investigate the roles of chemotaxis and geometry in transport of bio-hybrid drug delivery vehicles. Our experimental results demonstrate for the first time that bacterial chemotactic response dominates the effect of body shape in extravascular transport; thus, the non-spherical system could be more favorable for drug delivery applications owing to the known benefits of using non-spherical particles for vascular transport (e.g. relatively long circulation time).  相似文献   
969.

Background

Although in its infancy, the field of e-mental health interventions has been gaining popularity and afforded considerable research attention. However, there are many gaps in the research. One such gap is in the area of attrition predictors at various stages of assessment and treatment delivery.

Objective

This exploratory study applied univariate and multivariate analysis to a large dataset provided by the Anxiety Online (now called Mental Health Online) system to identify predictors of attrition in treatment commencers and in those who formally withdrew during treatment based on 24 pretreatment demographic and personal variables and one clinical measure.

Methods

Participants were assessed using a complex online algorithm that resulted in primary and secondary diagnoses in accordance with the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR). Those who received a primary or secondary diagnosis of 1 of 5 anxiety disorders (generalized anxiety disorder, social anxiety disorder, obsessive-compulsive disorder, posttraumatic stress disorder, and panic disorder) were offered an online 12-week disorder-specific treatment program.

Results

Of 9394 potential participants, a total of 3880 clients enrolled and 5514 did not enroll in one of the treatment programs following the completion of pretreatment assessment measures (pretreatment attrition rate: 58.70%). A total of 3199 individuals did not formally withdraw from the 12-week treatment cycle, whereas 142 individuals formally dropped out (formal withdrawal during treatment dropout rate of 4.25%). The treatment commencers differed significantly (P<.001-.03) from the noncommencers on several variables (reason for registering, mental health concerns, postsecondary education, where first heard about Anxiety Online, Kessler-6 score, stage of change, quality of life, relationship status, preferred method of learning, and smoking status). Those who formally withdrew during treatment differed significantly (P=.002-.03) from those who did not formally withdraw in that they were less likely to express concerns about anxiety, stress, and depression; to rate their quality of life as very poor, poor, or good; to report adequate level of social support; and to report readiness to make or were in the process of making changes.

Conclusions

This exploratory study identified predictors of pretreatment attrition and formal withdrawal during treatment dropouts for the Anxiety Online program.

Trial Registration

Australian and New Zealand Clinical Trials Registry ACTRN121611000704998; http://www.anzctr.org.au/trial_view.aspx?ID=336143 (Archived by WebCite at http://www.webcitation.org/618r3wvOG).  相似文献   
970.
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