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   1460篇
  免费   108篇
  国内免费   9篇
耳鼻咽喉   14篇
儿科学   17篇
妇产科学   23篇
基础医学   216篇
口腔科学   119篇
临床医学   134篇
内科学   282篇
皮肤病学   44篇
神经病学   129篇
特种医学   56篇
外科学   142篇
综合类   3篇
预防医学   139篇
眼科学   19篇
药学   110篇
中国医学   16篇
肿瘤学   114篇
  2023年   37篇
  2022年   68篇
  2021年   109篇
  2020年   71篇
  2019年   92篇
  2018年   97篇
  2017年   69篇
  2016年   73篇
  2015年   72篇
  2014年   90篇
  2013年   93篇
  2012年   123篇
  2011年   109篇
  2010年   56篇
  2009年   46篇
  2008年   51篇
  2007年   53篇
  2006年   49篇
  2005年   26篇
  2004年   29篇
  2003年   24篇
  2002年   19篇
  2000年   5篇
  1999年   4篇
  1998年   5篇
  1996年   3篇
  1995年   2篇
  1994年   4篇
  1993年   3篇
  1992年   4篇
  1991年   2篇
  1990年   5篇
  1989年   4篇
  1988年   8篇
  1987年   7篇
  1986年   9篇
  1985年   4篇
  1984年   2篇
  1983年   9篇
  1980年   4篇
  1979年   3篇
  1978年   4篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1974年   8篇
  1973年   4篇
  1972年   5篇
  1971年   4篇
  1970年   1篇
排序方式: 共有1577条查询结果,搜索用时 46 毫秒
81.
Maternal salt overload programs cardiovascular and renal alterations in the offspring. However, beneficial and harmful effects of high dose vitamin E supplementation have been described in humans and animals. We investigated the hypothesis as to whether cardiac and renal alterations can be programmed by gestational salt overload, and can become further modified during lactation and after weaning. Male Wistar rats were used, being the offspring of mothers that drank either tap water or 0.3 mol/L NaCl for 20 days before and during pregnancy. α‐Tocopherol (0.35 g/kg) was administered to mothers daily during lactation or to their offspring for 3 weeks post‐weaning. Systolic blood pressure (tcSBP) was measured in juvenile rats aged 210 days. The response of mean arterial pressure (MAP) and heart rate (HR) to intravenous infusion of angiotensin II (Ang II) was also examined. Left ventricle plasma membrane (PMCA) and sarcoplasmic reticulum Ca2+‐ATPase (SERCA) activities, and certain parameters of renal function, were measured. Maternal saline programmed for increased body mass and kidney mass/body mass ratio, increased tcSBP, increased mean arterial pressure and heart rate with anomalous response to infused Ang II. In the heart, saline increased PMCA and α‐Tocopherol per se increased PMCA/SERCA. In the kidney, the most remarkable result was the silent saline programming of CrCl, which was sensitized for a sharp decrease after α‐Tocopherol. In conclusion, the combination of maternal saline overload and high α‐Tocopherol immediately after birth leads to simultaneous cardiovascular and renal alterations in the young offspring, like those encountered in type V cardiorenal syndrome.  相似文献   
82.
This study explores the way the publication of a National White Book on health and safety risks that affect workers in jobs involving Nanotechnologies and Nanomaterials influenced the key Italian stakeholders attitude toward this issue and identifies the standpoints and priorities shared among researchers and stakeholders to develop a policy framework to address this issue.  相似文献   
83.
Few studies have focused on the release of toxic elements from oil well drill cuttings and their effect on soil. The present study evaluated these effects using rice growth as the endpoint. Drill cuttings were collected from a Brazilian well and added in doses of 300, 3,000 and 6,000 mg kg?1 soil, which was maintained at oxidized or reduced conditions. When the redox potential reached approximately ?250 mV, barium concentrations were determined by geochemical fractionation. Overall, doses of 300 and 3,000 mg kg?1 promoted plant development, while a dose of 6,000 mg kg?1 inhibited it due to the associated increase in electrical conductivity and exchangeable sodium concentration. In addition, the lower redox potential promoted solubilization of barite from the drill cuttings, which increased barium absorption by plants and translocation to grain, posing a risk to human health.  相似文献   
84.

Objectives

Weight gain is a concern with the contraceptive depot-medroxyprogesterone acetate (DMPA); however, this issue remains controversial. The objective of this study was to compare body weight (BW) and body composition (BC) in DMPA and copper intrauterine device (IUD) users at baseline and after one year of use.

Study Design

We enrolled new DMPA users and age and weight matched new IUD users into this prospective study. Weight and height were measured, BC (fat and lean mass) was evaluated using dual-energy X-ray absorptiometry, and physical activity was assessed at baseline and at 12 months. Student's paired t test and the Wilcoxon paired test for matched samples were used.

Results

Ninety-seven women were enrolled for the study; 26 matched pairs continued using the initial method for at least one year, and completed the baseline and 12 month assessments. An increase of 1.9 kg occurred in BW (p=.02) in DMPA users at 12 months of use, resulting from an increase in fat mass of 1.6 kg (p=.03). Weight remained stable in IUD users; however, there was an increase in lean mass at 12 months of use (p=.001). The number of women practicing physical activity increased in this group. There was a significant difference between the groups regarding the variation in the percentage of central fat (p=.04).

Conclusion

Weight gain in the DMPA group after the first year of use resulted from an increase in fat mass. Weight remained stable in the IUD group; however, an increase in lean mass and a reduction in localized abdominal fat mass occurred, possibly because more users were practicing physical activity.

Implications statement

There was a greater increase in body weight in DMPA users compared to TCu380A IUD users in the first year of use of the contraceptive method. Furthermore, the weight increase in users of DMPA occurred principally as the result of an increase in fat mass. Physical activity probably could increase the lean mass in the users of TCu380A IUD.  相似文献   
85.

Background:

Physiotherapy in the plastic surgery post-operative (PO) is essential to provide means for an adequate and fast recovery as it restores function through the use of physiotherapeutic procedures.

Aim:

The aim of the following study is to verify the effects of the association between the manual lymphatic drainage and the therapeutic ultrasound on pain, oedema and the tissue fibrosis in liposuction and lipoabdominoplasty PO.

Design:

This is a clinical trial prospective.

Materials and Methods:

Eighteen women aged between 18 and 60 years participated in this study, in the late PO period following lipoabdominoplasty or liposuction in the abdomen, flanks and lower trunk, which showed tissue fibrosis of the flanks and abdomen regions. They were divided into two groups: Liposuction group and lipoabdominoplasty group. A total of twelve sessions of therapeutic ultrasound followed by the manual lymphatic drainage were performed. The patients were assessed with regard to pain, oedema and tissue fibrosis in different moments: Initial assessment, during assessment and final assessment through the application of the protocol of evaluation of cysts fibrosis levels.

Statistical Analysis:

The test of equality for two proportions and the confidence interval test for mean to evaluate the distribution of variables. The significance level adopted for statistical tests was 5% (P < 0.05).

Results:

There was a statistically significant reduction of pain, swelling and tissue fibrosis in both groups.

Conclusion:

the association between manual lymphatic drainage and the therapeutic ultrasound reduced the swelling and the tissue fibrosis and made pain disappear in liposuction and lipoabdominoplasty PO period.KEY WORDS: Oedema, lipectomy, lymphatic system, plastic, surgery, ultrasound therapy  相似文献   
86.
87.
Components of high molecular-weight (PI) obtained from Ascaris suum extract down-regulate the Th1/Th2-related immune responses induced by ovalbumin (OVA)-immunization in mice. Furthermore, the PI down-modulates the ability of dendritic cells (DCs) to activate T lymphocytes by an IL-10-mediated mechanism. Here, we evaluated the role of toll like receptors 2 and 4 (TLR2 and 4) in the modulatory effect of PI on OVA-specific immune response and the PI interference on DC full activation. An inhibition of OVA-specific cellular and humoral responses were observed in wild type (WT) or in deficient in TLR2 (TLR2−/−) or 4 (TLR4−/−) mice immunized with OVA plus PI when compared with OVA-immunized mice. Low expression of class II MHC, CD40, CD80 and CD86 molecules was observed in lymph node (LN) cells from WT, TLR2−/− or TLR4−/− mice immunized with OVA plus PI compared with OVA-primed cells. We also verified that PI was able to modulate the activation of DCs derived from bone marrow of WT, TLR2−/− or TLR4−/− mice induced in vitro by agonists of TLRs, as observed by a decreased expression of class II MHC and costimulatory molecules and by low secretion of pro-inflammatory cytokines. Its effect was accompanied by IL-10 synthesis. In this sense, the modulatory effect of PI on specific-immune response and DC activation is independent of TLR2 or TLR4.  相似文献   
88.
Since Helicobacter spp. DNA was identified in liver tissue resected from patients with hepatocelullar carcinoma (HCC), researchers have suggested a role of this bacterium in hepatic carcinogenesis. Archives of formalin-fixed, paraffin-embedded (FFPE) tissues represent an extraordinary source for clinical studies providing many advantages. However, DNA extraction from FFPE tissues is laborious, time-consuming and still remains a challenge. The aim of this study was to evaluate five protocols for DNA extraction from FFPE liver obtained from patients with HCC in order to detect Helicobacter pylori DNA. These methods were: (1) QIAamp FFPE Tissue Kit, (2) QIAamp DNA Mini Kit, (3) Wizard SV Genomic DNA Purification System, (4) RealiaPrep FFPE gDNA Miniprep System and (5) phenol–chloroform. H. pylori detection was performed using 16S rRNA gene amplification by PCR. The highest total amount of DNA was obtained using the phenol–chloroform method. Analyses of 16S rRNA gene amplification did not show statistically significant differences among the methods (p = 0.466), although the highest percentage of positive cases (70%) was found in samples extracted with phenol-chloroform. We suggest that of the five methods evaluated, phenol/chloroform is the most suitable for detection of H. pylori in FFPE liver from patients with HCC.  相似文献   
89.
90.
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