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   59289篇
  免费   3141篇
  国内免费   602篇
耳鼻咽喉   226篇
儿科学   1661篇
妇产科学   758篇
基础医学   3755篇
口腔科学   971篇
临床医学   6956篇
内科学   6986篇
皮肤病学   637篇
神经病学   2786篇
特种医学   1017篇
外国民族医学   5篇
外科学   3043篇
综合类   6453篇
现状与发展   4篇
一般理论   6篇
预防医学   17524篇
眼科学   507篇
药学   5872篇
  38篇
中国医学   1784篇
肿瘤学   2043篇
  2023年   1004篇
  2022年   1677篇
  2021年   2538篇
  2020年   2498篇
  2019年   3317篇
  2018年   2959篇
  2017年   2180篇
  2016年   1694篇
  2015年   1834篇
  2014年   4181篇
  2013年   4371篇
  2012年   3575篇
  2011年   3826篇
  2010年   2943篇
  2009年   2799篇
  2008年   2735篇
  2007年   2623篇
  2006年   2093篇
  2005年   1529篇
  2004年   1269篇
  2003年   1095篇
  2002年   864篇
  2001年   732篇
  2000年   625篇
  1999年   535篇
  1998年   491篇
  1997年   430篇
  1996年   319篇
  1995年   301篇
  1994年   271篇
  1993年   254篇
  1992年   262篇
  1991年   230篇
  1990年   200篇
  1989年   190篇
  1988年   192篇
  1987年   185篇
  1986年   167篇
  1985年   417篇
  1984年   544篇
  1983年   396篇
  1982年   449篇
  1981年   391篇
  1980年   341篇
  1979年   322篇
  1978年   267篇
  1977年   219篇
  1976年   193篇
  1975年   156篇
  1974年   131篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
I use 28 (1986–2014) years of restricted geocoded NLSY tract-level data and find positive associations between exposure to childhood neighborhood disadvantage and adult obesity and BMI among individuals growing up and entering adulthood during the rise of obesity in the United States. Sibling fixed effects and cousin fixed effects models partially address unobserved confounding nested in the nuclear as well as extended family. Furthermore, exposure to neighborhood disadvantage in adolescence is most salient, providing insight into when policy intervention may be most effective. Results are robust to alternative specifications for neighborhood disadvantage, ages of exposure, and to alternative sampling strategies.  相似文献   
72.
目的探讨依维莫司联合全反式维甲酸(简称维甲酸)逆转急性早幼粒细胞白血病(APL)细胞株NB4-R1耐药的作用。方法应用CD11b染色流式细胞术及硝基四唑氮蓝(NBT)还原实验检测两药联合应用对细胞分化的影响, 流式细胞术检测细胞周期情况, Annexin V/PI双染色检测细胞凋亡情况, 蛋白质印迹法检测自噬相关蛋白微管结合蛋白轻链3(LC3)、Beclin 1及早幼粒白血病-维甲酸受体融合蛋白(PML-RARα)、磷酸化核糖体S6激酶(P-P70S6K)、磷酸化4E结合蛋白1(P-4E-BP1) 等表达水平。结果与维甲酸组比较, 联用组能诱导耐药细胞株NB4-R1细胞的分化, 并将细胞增殖阻止在G 1期而对细胞凋亡无明显影响。100 nmol/L依维莫司组、1μmol/L维甲酸组、联用组、对照组NB4-R1细胞培养48 h后分化百分率分别为(2.29±0.57)%、(17.06±2.65)%、(54.47±4.91)%、(2.54±0.53)%; 处于G 1期的细胞百分率分别为(35.20±11.97)%、(33.54±6.25)%、(53.70±8.73)%、(27.40±6.01)%; 四组细胞凋亡细胞百分率分别为(2.30±0.14)%、(2.25±0.21)%、(2.40±0.28)%、(1.95±0.07)%。与维甲酸组比较, 联用组mTOR信号通路下游的P70S6K、4E-BP1分子磷酸化水平下降, LC3-II和Beclin 1的表达上调, 且能部分降解融合蛋白PML-RARα。 结论依维莫司联合维甲酸能诱导NB4-R1细胞分化, 且能阻滞细胞周期而不致细胞凋亡, 其机制可能与依维莫司联合维甲酸抑制mTOR信号通路激活自噬作用从而降解PML-RARα蛋白有关。  相似文献   
73.
74.
75.
Despite a population of nearly 60 million, there is currently not a single interventional radiologist in Tanzania. Based on an Interventional Radiology (IR) Readiness Assessment, the key obstacles to establishing IR in Tanzania are the lack of training opportunities and limited availability of disposable equipment. An IR training program was designed and initiated, which relies on US-based volunteer teams of IR physicians, nurses, and technologists to locally train radiology residents, nurses, and technologists. Preliminary results support this strategy for addressing the lack of training opportunities and provide a model for introducing IR to other resource-limited settings.  相似文献   
76.
77.
ObjectivePilates is used increasingly in a variety of clinical settings. However, there is lack of clarity in the literature as to what is meant by the term. Teachers incorporating apparatus based on the designs of Joseph Pilates (1883–1967) into their practice refer to themselves as Comprehensive Teachers, and this group divides itself further into Classical and Contemporary practice. The aim of this research was to explore the meanings of these terms with Comprehensive Teachers and to develop a framework that reflects current views and practice.MethodOnline international survey of Pilates Teachers through closed Facebook forums. Open questions were used to elicit views of the definition and practice of Pilates, and how standards should be set across the sector.ResultsOf 109 participants, 35% were based in the UK and 32% in the USA; 48% identified as Classical teachers, 32% as Contemporary, 5% as both and 15% as Matwork instructors. A thematic analysis of the qualitative data revealed agreement on the scope and content of Classical and Contemporary Comprehensive Pilates, however the discourse indicated there might be stereotyping about each other's practice. Classical teachers, for example, spoke of their own practice as authentic while Contemporary teachers used terms such as strict and inflexible for Classical practice. However, members of either group may incorporate both Classical and Contemporary approaches within their practice. We have designed a Pilates Teaching Framework to take into account the types of apparatus, the types of exercises and the order in which the exercises are executed.ConclusionsA framework that emphasises Pilates teaching rather than teacher practice is proposed for consistency and clarity when describing Pilates in professional and public contexts.  相似文献   
78.
On February 20, 2020, a man living in the north of Italy was admitted to the emergency room with an atypical pneumonia that later proved to be COVID-19. This was the trigger of one of the most serious clusters of COVID-19 in the world, outside of China. Despite aggressive restraint and inhibition efforts, COVID-19 continues to increase, and the total number of infected patients in Italy is growing daily. After 6 weeks, the total number of patients reached 128,948 cases (April 5, 2020), with the higher case-fatality rate (15,887 deaths) dominated by old and very old patients.This sudden health emergency severely challenged the Italian Health System, in particular acute care hospitals and intensive care units. In 1 hospital, geriatric observation units were created, the experience of which can be extremely useful for European countries, the United States, and all countries that in the coming days will face a similar situation.  相似文献   
79.
The inflammatory response induced by cardiopulmonary bypass decreases vascular tone, which in turn can lead to vasoplegic syndrome. Indeed the hypotension consequent to on-pump cardiac surgery often necessitates vasopressor and intravenous fluid support. Methylene blue counteracts vasoplegic syndrome by inhibiting the formation of nitric oxide.We report the use of methylene blue in a 75-year-old man who developed vasoplegic syndrome after cardiac surgery. After the administration of methylene blue, his hypotension improved to the extent that he could be weaned from vasopressors. The use of methylene blue should be considered in patients who develop hypotension refractory to standard treatment after cardiac surgery.  相似文献   
80.
BackgroundDuring COVID-19 pandemic, a shortage of surgical masks (Mask) and respirators (Resp) was experienced worldwide. We aimed to assess its pattern of use, adverse effects and user errors by Portuguese health care professionals (HCP).MethodsA cross-sectional study was conducted through snowball convenience sample, collected by email/ social media to health care organizations. Participants answered an online anonymous survey in March 2021.ResultsMean age of 3052 respondents was 42.1 years old, 83.6% were female and 77.8% provided direct health care to COVID-19 patients. Mean time of use per shift was 6-8 hours in 40.8% of the participants. 28.0% reported never changing it during their shift. Resp use (vs Mask) was more associated with discomfort (58.2% vs 26.8%), affecting task performance (41.5 vs 18.9%) and communication (55.0 vs 40.9%), dyspnea (36.0 vs 14.4%), skin rash (37.5 vs 19.4%) and headache (37.5 vs 19.4%). Frequent user errors included touching the front while in use (70.1% Mask vs 66.3% Resp) and omitting hand hygiene before (61.8% Mask vs 55.0% Resp) or after use (61.3% Mask vs 57.0% Resp). Average number of errors was higher for Mask (4.3), than for Resp (3.2) (all: P < .001).ConclusionsMost HCP admitted an extended use of Mask/ Resp. Resp were more prone to adverse effects and Mask more prone to errors. Strategies to reinforce good practices should be considered.  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