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   2577篇
  免费   136篇
  国内免费   8篇
耳鼻咽喉   56篇
儿科学   110篇
妇产科学   51篇
基础医学   227篇
口腔科学   55篇
临床医学   250篇
内科学   500篇
皮肤病学   23篇
神经病学   204篇
特种医学   69篇
外国民族医学   7篇
外科学   533篇
综合类   37篇
一般理论   2篇
预防医学   179篇
眼科学   54篇
药学   188篇
中国医学   2篇
肿瘤学   174篇
  2023年   21篇
  2022年   42篇
  2021年   81篇
  2020年   58篇
  2019年   71篇
  2018年   90篇
  2017年   74篇
  2016年   69篇
  2015年   65篇
  2014年   100篇
  2013年   125篇
  2012年   232篇
  2011年   222篇
  2010年   110篇
  2009年   87篇
  2008年   162篇
  2007年   172篇
  2006年   148篇
  2005年   121篇
  2004年   135篇
  2003年   96篇
  2002年   99篇
  2001年   36篇
  2000年   25篇
  1999年   27篇
  1998年   16篇
  1997年   4篇
  1996年   21篇
  1995年   13篇
  1994年   7篇
  1993年   6篇
  1992年   23篇
  1991年   19篇
  1990年   12篇
  1989年   12篇
  1988年   20篇
  1987年   14篇
  1986年   9篇
  1985年   7篇
  1984年   6篇
  1983年   6篇
  1982年   6篇
  1981年   5篇
  1979年   9篇
  1977年   3篇
  1975年   8篇
  1972年   3篇
  1971年   3篇
  1968年   4篇
  1965年   3篇
排序方式: 共有2721条查询结果,搜索用时 46 毫秒
31.
32.
33.

Background

Although used as criterion for early drain removal, postoperative day (POD) 1 drain fluid amylase (DFA) ≤ 5000 U/L has low negative predictive value for clinically relevant postoperative pancreatic fistula (CR-POPF). It was hypothesized that POD3 DFA ≤ 350 could provide further information to guide early drain removal.

Methods

Data from a pancreas surgery consortium database for pancreatoduodenectomy and distal pancreatectomy patients were analyzed retrospectively. Those patients without drains or POD 1 and 3 DFA data were excluded. Patients with POD1 DFA ≤ 5000 were divided into groups based on POD3 DFA: Group A (≤350) and Group B (>350). Operative characteristics and 60-day outcomes were compared using chi-square test.

Results

Among 687 patients in the database, all data were available for 380. Fifty-five (14.5%) had a POD1 DFA > 5000. Among 325 with POD1 DFA ≤ 5000, 254 (78.2%) were in Group A and 71 (21.8%) in Group B. Complications (35 (49.3%) vs 87 (34.4%); p = 0.021) and CR-POPF (13 (18.3%) vs 10 (3.9%); p < 0.001) were more frequent in Group B.

Conclusions

In patients with POD1 DFA ≤ 5000, POD3 DFA ≤ 350 may be a practical test to guide safe early drain removal. Further prospective testing may be useful.  相似文献   
34.
35.
36.
BACKGROUND: Increased sodium intake has been positively associated with high blood pressure (BP) and hypertensive target organ damage, but associations with cardiac structure in nonhypertensive individuals have yielded inconsistent results. We tested the hypothesis that sodium intake is associated with left ventricular (LV) mass and left ventricular hypertrophy (LVH), independent of BP, in the community. METHODS: We analyzed the cross-sectional relationships between urinary sodium excretion and LV measurements in a community-based sample of 2660 Framingham Offspring Study participants (mean age 58 years, 56% women and 44% men). Participants with known coronary artery disease, congestive heart failure, or renal failure as well as those using diuretics were excluded. Urinary sodium excretion was measured on a spot urine sample and was indexed to urinary creatinine. RESULTS: In sex-specific, multivariable linear regression models adjusting for covariates known to influence LV measurements, log urinary sodium was not associated with LV mass, wall thickness, end-diastolic dimensions, or left atrial size in either sex. Urinary sodium was not related to LVH defined as LV mass >/= sex-specific 80th percentile value. In analyses restricted to hypertensive individuals (n = 983, 470 women), urinary sodium was not associated with LV mass or LVH. CONCLUSIONS: In our large community-based sample, urinary sodium excretion was not related to LV mass, function, or hypertrophy.  相似文献   
37.
OBJECTIVE: Our objective was to compare the effects of oral vs. transdermal estrogen therapy on C-reactive protein (CRP), IL-6, E- and P-selectin, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule-1, serum amyloid A, transferrin, prealbumin, IGF-I, SHBG, thyroxine-binding globulin (TBG), and cortisol-binding globulin (CBG) in naturally menopausal women. DESIGN: This was a randomized, open-label crossover clinical trial. A 6-wk withdrawal from prior hormone therapy (baseline) was followed in randomized order by 12-wk oral conjugated equine estrogens (CEEs) (0.625 mg/d) and 12-wk transdermal estradiol (E2) (0.05 mg/d), with oral micronized progesterone (100 mg/d) given continuously during both regimens. RESULTS: A total of 27 women enrolled, and 25 completed both treatment periods. Nine parameters changed significantly during oral CEE (median percent change from baseline; P value): CRP (192%; P <0.001); E-selectin (-16.3%; P = 0.003); P-selectin (-15.3%; P = 0.012); ICAM-1 (-5%; P = 0.015); transferrin (5.3%; P = 0.024); IGF-I (-30.5%; P < 0.001); SHBG (113%; P < 0.001); TBG (38%; P < 0.001); and CBG (20%; P < 0.001). With transdermal E2, only three parameters changed significantly and to a lesser degree: ICAM-1 (-2.1%; P = 0.04); IGF-I (-12.5%; P < 0.001); and SHBG (2.6%; P = 0.042). During oral CEE the intrasubject changes in CRP correlated strongly with the changes in serum amyloid A (r = 0.805; P < 0.001), and were only weakly associated with the changes in SHBG (r = 0.248; nonsignificant), TBG (0.430; P = 0.031), and CBG (r = 0.072; nonsignificant). The log-log relationship between CRP and IL-6 observed at baseline showed a parallel shift during oral CEE, suggesting an amplified hepatic response or a greater sensitivity to IL-6 stimulation. CONCLUSION: Compared with oral CEE, transdermal E2 exerts minimal effects on CRP and the other inflammation and hepatic parameters.  相似文献   
38.
The cytotoxic T lymphocyte (CTL) response was evaluated in adults given live attenuated varicella vaccine, using target cells expressing varicella-zoster virus (VZV) immediate-early protein (IE62) or VZV glycoproteins gpI, gpIV, or gpV to determine viral protein specificity. The frequency of CTL that recognized IE62 was 1:171,000 +/- 46,000 SE in subjects tested 10 days to 8 weeks after the initial vaccine dose; the induction of CTL specific for gpI was equivalent. CTL recognition of VZV proteins was mediated by CD4+ or CD8+ cells. CTL recognition of IE62 and gpIV persisted in vaccinees (tested approximately 4 years later) and was comparable to that in the naturally immune. The mean frequency of CTL specific for gpV was lower (but not significantly) in vaccinees than in naturally immune subjects. Assay of responder cell frequencies showed persistence of equivalent numbers of T lymphocytes that recognized IE62 and gpI in vaccinees and naturally immune subjects. Immunization with this vaccine elicited memory T lymphocyte responses to VZV comparable to those induced by natural infection.  相似文献   
39.
Epstein–Barr virus (EBV) is a ubiquitous herpesvirus with rare but severe potential for lymphoproliferative complications. EBV is associated with a variety of presentations of haemophagocytic lymphohistiocytosis (HLH). HLH is a life-threatening hyperinflammatory syndrome that can occur in patients with genetic defects associated with dysregulation of the immune response (familial HLH) or arise in patients with underlying infection or malignancy (non-familial or secondary HLH). EBV can both serve as the incidental trigger of familial HLH or as the driving factor in patients with selective inherited vulnerability (e.g. X-linked lymphoproliferative disease). Alternatively, acute infection can idiosyncratically cause non-neoplastic HLH in patients without inherited predisposition (i.e. secondary HLH), while EBV-associated T/natural killer (NK)-cell lymphoproliferative disorders and lymphomas can cause neoplasia-associated HLH. The present review will discern between EBV-associated familial and non-familial HLH and highlight diagnostic and therapeutic considerations. Non-familial EBV-associated HLH is a major diagnostic dilemma, as it represents a diverse spectrum of disease ranging from highly curable (non-neoplastic EBV-HLH) to indolent but incurable (chronic active EBV) to acutely fatal (systemic EBV-positive T-cell lymphoma of childhood). Increased clinical awareness and understanding of this rare and potentially devastating subset of EBV-related complications is desperately needed to improve survival for patients with neoplasia-associated HLH.  相似文献   
40.
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