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   3019篇
  免费   200篇
  国内免费   5篇
耳鼻咽喉   22篇
儿科学   110篇
妇产科学   202篇
基础医学   429篇
口腔科学   78篇
临床医学   275篇
内科学   798篇
皮肤病学   47篇
神经病学   375篇
特种医学   65篇
外科学   267篇
综合类   11篇
一般理论   2篇
预防医学   194篇
眼科学   29篇
药学   147篇
中国医学   3篇
肿瘤学   170篇
  2023年   35篇
  2022年   50篇
  2021年   131篇
  2020年   50篇
  2019年   116篇
  2018年   128篇
  2017年   86篇
  2016年   95篇
  2015年   84篇
  2014年   129篇
  2013年   169篇
  2012年   237篇
  2011年   217篇
  2010年   121篇
  2009年   113篇
  2008年   184篇
  2007年   168篇
  2006年   179篇
  2005年   169篇
  2004年   161篇
  2003年   113篇
  2002年   114篇
  2001年   17篇
  2000年   24篇
  1999年   16篇
  1998年   28篇
  1997年   18篇
  1996年   20篇
  1995年   10篇
  1994年   12篇
  1993年   23篇
  1992年   8篇
  1991年   17篇
  1990年   11篇
  1989年   10篇
  1988年   19篇
  1987年   12篇
  1986年   16篇
  1985年   10篇
  1983年   12篇
  1981年   7篇
  1979年   4篇
  1978年   6篇
  1977年   5篇
  1976年   5篇
  1975年   8篇
  1974年   7篇
  1973年   4篇
  1967年   8篇
  1966年   4篇
排序方式: 共有3224条查询结果,搜索用时 15 毫秒
61.
62.
63.
Annals of Hematology - Despite the low risk of peripherally inserted central catheter (PICC) insertion-related bleeding, the practice of administering prophylactic platelets varies greatly....  相似文献   
64.
Folayan  Morenike Oluwatoyin  Ibigbami  Olanrewaju  Brown  Brandon  El Tantawi  Maha  Uzochukwu  Benjamin  Ezechi  Oliver C.  Aly  Nourhan M.  Abeldaño  Giuliana Florencia  Ara  Eshrat  Ayanore  Martin Amogre  Ayoola  Oluwagbemiga O.  Osamika  Bamidele Emmanuel  Ellakany  Passent  Gaffar  Balgis  Idigbe  Ifeoma  Ishabiyi  Anthonia Omotola  Jafer  Mohammed  Khan  Abeedha Tu-Allah  Khalid  Zumama  Lawal  Folake Barakat  Lusher  Joanne  Nzimande  Ntombifuthi P.  Popoola  Bamidele Olubukola  Quadri  Mir Faeq Ali  Rashwan  Maher  Roque  Mark  Shamala  Anas  Al-Tammemi  Ala’a B.  Yousaf  Muhammad Abrar  Abeldaño Zuñiga  Roberto Ariel  Okeibunor  Joseph Chukwudi  Nguyen  Annie Lu 《AIDS and behavior》2022,26(3):739-751
AIDS and Behavior - The aim of the study was to assess if there were significant differences in the adoption of COVID-19 risk preventive behaviors and experience of food insecurity by people living...  相似文献   
65.
66.

Objectives

The purpose of this study was to describe patients with severe symptomatic aortic stenosis with normal flow and low gradients and determine whether they benefit from intervention.

Background

Severe symptomatic aortic stenosis is a progressive disease with high mortality. Although surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR) are indicated for patients with high gradients (>40 mm Hg) or low gradients due to low flow, the approach for patients with normal flow and low gradients is poorly defined.

Methods

Consecutive adult patients who underwent echocardiography between 2012 and 2015 at Tel-Aviv Medical Center and had an aortic valve area of ≤1.0 cm2, a mean gradient of <40 mm Hg, a stroke volume index of >35 ml/m2, and symptoms formed the study group. Patients designated for intervention (SAVR or TAVR) had their procedure within 6 months of the echocardiogram; the others were treated conservatively. The endpoints were all-cause mortality and cardiac-related mortality.

Results

During the study period, 1,358 patients with an aortic valve area of ≤1.0 cm2 and symptoms were identified; 34% of these had normal flow and low gradient aortic stenosis and 303 were included. After mean follow-up of 652 days, 60 patients (20%) had died, with overall mortality rates of 28%, 10%, and 12% for conservatively treated, TAVR, and SAVR patients, respectively (p < 0.001). Using Cox regression with adjustment for other variables, TAVR was associated with improved survival versus conservative treatment (hazard ratio [HR]: 0.49; 95% confidence interval [CI]: 0.26 to 0.93; p = 0.03), and lower cardiac mortality (HR: 0.30; 95% CI: 0.10 to 0.74; p = 0.007) with no significant difference for SAVR versus TAVR. After propensity score matching of TAVR and conservatively treated patients, 25 of 94 (28%) conservatively treated and 10 of 94 (12%) TAVR patients had died (p = 0.016). In the matched cohort, Cox regression showed that TAVR had a significant association with improved survival (HR: 0.42; 95% CI: 0.20 to 0.86; p = 0.03).

Conclusions

Symptomatic patients with an aortic valve area of ≤1.0 cm2, normal flow, and low gradient may benefit from intervention as opposed to conservative treatment.  相似文献   
67.
We studied plasma ghrelin and GH concentrations over a 24-h period in young healthy men and women and in patients with acromegaly. Healthy subjects were restudied after administration of GH-lowering agents, octreotide or GHRH antagonist. Ghrelin concentrations in women studied during the late follicular stage of the cycle were about 3-fold higher than in men. Suppression of GH secretion by GHRH antagonist did not alter ghrelin concentration profiles. In the presence of high GH levels (acromegaly), ghrelin levels were similar to those found in healthy men. Administration of somatostatin analog octreotide suppressed both GH and ghrelin concentration profiles. We conclude that: 1) ghrelin secretion is sexually dimorphic in humans, with women in the late follicular stage having higher levels than men; 2) ghrelin secretion is suppressed by somatostatin; and 3) GH has no influence over ghrelin secretion.  相似文献   
68.
BACKGROUNDThe significant risks posed to mothers and fetuses by COVID-19 in pregnancy have sparked a worldwide debate surrounding the pros and cons of antenatal SARS-CoV-2 inoculation, as we lack sufficient evidence regarding vaccine effectiveness in pregnant women and their offspring. We aimed to provide substantial evidence for the effect of the BNT162b2 mRNA vaccine versus native infection on maternal humoral, as well as transplacentally acquired fetal immune response, potentially providing newborn protection.METHODSA multicenter study where parturients presenting for delivery were recruited at 8 medical centers across Israel and assigned to 3 study groups: vaccinated (n = 86); PCR-confirmed SARS-CoV-2 infected during pregnancy (n = 65), and unvaccinated noninfected controls (n = 62). Maternal and fetal blood samples were collected from parturients prior to delivery and from the umbilical cord following delivery, respectively. Sera IgG and IgM titers were measured using the Milliplex MAP SARS-CoV-2 Antigen Panel (for S1, S2, RBD, and N).RESULTSThe BNT162b2 mRNA vaccine elicits strong maternal humoral IgG response (anti-S and RBD) that crosses the placenta barrier and approaches maternal titers in the fetus within 15 days following the first dose. Maternal to neonatal anti-COVID-19 antibodies ratio did not differ when comparing sensitization (vaccine vs. infection). IgG transfer ratio at birth was significantly lower for third-trimester as compared with second trimester infection. Lastly, fetal IgM response was detected in 5 neonates, all in the infected group.CONCLUSIONAntenatal BNT162b2 mRNA vaccination induces a robust maternal humoral response that effectively transfers to the fetus, supporting the role of vaccination during pregnancy.FUNDINGIsrael Science Foundation and the Weizmann Institute Fondazione Henry Krenter.  相似文献   
69.
70.
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