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   560篇
  免费   42篇
  国内免费   4篇
耳鼻咽喉   3篇
儿科学   9篇
妇产科学   6篇
基础医学   111篇
口腔科学   11篇
临床医学   52篇
内科学   92篇
皮肤病学   14篇
神经病学   53篇
特种医学   14篇
外科学   36篇
综合类   9篇
一般理论   2篇
预防医学   56篇
眼科学   15篇
药学   63篇
中国医学   6篇
肿瘤学   54篇
  2024年   1篇
  2023年   11篇
  2022年   19篇
  2021年   47篇
  2020年   20篇
  2019年   22篇
  2018年   29篇
  2017年   15篇
  2016年   31篇
  2015年   26篇
  2014年   42篇
  2013年   43篇
  2012年   50篇
  2011年   54篇
  2010年   25篇
  2009年   20篇
  2008年   35篇
  2007年   26篇
  2006年   28篇
  2005年   15篇
  2004年   18篇
  2003年   6篇
  2002年   6篇
  2001年   1篇
  2000年   1篇
  1991年   1篇
  1990年   1篇
  1989年   3篇
  1988年   2篇
  1987年   1篇
  1983年   1篇
  1981年   1篇
  1979年   2篇
  1977年   1篇
  1973年   1篇
  1969年   1篇
排序方式: 共有606条查询结果,搜索用时 15 毫秒
1.
2.
A recently independent state, Timor-Leste, is progressing towards socioeconomic development, prioritizing women empowerment while its increased fertility rate (4.1) could hinder the growth due to an uncontrolled population. Currently, limited evidence shows that indicators of women''s empowerment are associated with fertility preferences and rates. The objective of this study was to assess the association between women empowerment and fertility preferences of married women aged 15 to 49 years in Timor-Leste using nationally representative survey data. The study was conducted using the data of the latest Timor-Leste Demographic and Health Survey 2016. The study included 4040 rural residents and 1810 urban residents of Timor-Leste. Multinomial logistic regression has been performed to assess the strength of association between the exposures indicating women''s empowerment and outcome (fertility preference). After adjusting the selected covariates, the findings showed that exposures that indicate women empowerment in DHS, namely, the employment status of women, house and land ownership, ownership of the mobile phone, and independent bank account status, contraceptive use, and the attitude of women towards negotiating sexual relations are significantly associated with fertility preferences. The study shows higher the level of education, the less likely were the women to want more children, and unemployed women were with a higher number of children. Our study also found that the attitude of violence of spouses significantly influenced women''s reproductive choice. However, employment had no significant correlation with decision-making opportunities and contraceptive selection due to a lack of substantial data. Also, no meaningful data was available regarding decision-making and fertility preferences. Our findings suggest that women''s empowerment governs decision-making in fertility preferences, causing a decline in the fertility rate.  相似文献   
3.
4.
5.

Background

In every anatomic lung resection operation, the pulmonary artery itself or its branches must be sealed. This involves either stapling or ligating the vessels. Based on the positive results with the bipolar vessel sealing ≤7 mm in abdominal surgery the present study aimed to evaluate burst pressures of the pulmonary artery after sealing with the sealing instrument SealSafe G3 (Gebrüder Martin & CoKG, Tuttlingen, Germany).

Material and methods

The whole pulmonary artery above the pulmonary valve was exposed up to the periphery of the left lung in freshly removed pig heart–lung blocks. A pressure-measuring cylinder was then implanted in the prepared vessel on the side at the main trunk of the pulmonary artery to determine the pressure in the vessel. After either ligation or bipolar sealing of the pulmonary artery, the pneumatic burst pressure (millimeters of mercury) was determined in a water bath. Three groups (n = 12 for each seal type) with different vessel diameters were examined: group 1: 0–6 mm, group 2: 7–12 mm, and group 3: >12 mm. In all cases, vessel sealing was performed with a MARSEAL 5 instrument (Gebrüder Martin & Co KG, Tuttlingen, Germany) and the SealSafe G3 current. The mean burst pressures of the individual groups (ligature and bipolar sealing) were compared using two-tailed, nonparametric Mann–Whitney U test. Significance was defined as P < 0.05.

Results

The mean burst pressures in group 1 were measured by 340 ± 13.4 mm Hg with ligature and 205 ± 44.4 mm Hg with bipolar sealing (P < 0.001). In group 2, the mean values obtained were 270 ± 28.2 mm Hg for ligature and 162 ± 36.0 mm Hg for bipolar sealing (P < 0.001). In group 3, the mean burst pressures for bipolar sealing were only 52.1 ± 15.1 mm Hg, whereas those for ligated vessels were 253 ± 46.9 mm Hg (P < 0.001). For this size of vessel the burst pressure was also determined after stapling. The mean value in this case was 230 ± 21.8 mm Hg.

Conclusions

In all groups, the mean burst pressures after bipolar sealing were significantly lower than those achieved with ligation, but they were sufficient for a save closure of the pulmonary artery with diameters up to 12 mm.  相似文献   
6.
Optic disc pit (ODP) is small, gray-white, oval depression found at the optic nerve head. It is a congenital defect that occurs due to imperfect closure of superior edge of the embryonic fissure. Cleft lip and palate are also congenital midline abnormalities occurring due to defect in the fusion of frontonasal prominence, maxillary prominence and mandibular prominence. There is only one case report describing the occurrence of ODP in a young patient with cleft lip and palate who also had basal encephalocele. We describe a 52-year-old patient with congenital cleft lip and palate with bilateral ODP with maculopathy but without any other midline abnormality.  相似文献   
7.
The efficiency of μ-opioid receptor signalling is tightly regulated and ultimately limited by the coordinated phosphorylation of intracellular serine and threonine residues. Here, we review and discuss recent progress in the generation and application of phosphosite-specific μ-opioid receptor antibodies, which have proved to be excellent tools for monitoring the spatial and temporal dynamics of receptor phosphorylation and dephosphorylation. Agonist-induced phosphorylation of μ-opioid receptors occurs at a conserved 10 residue sequence 370TREHPSTANT379 in the receptor''s carboxyl-terminal cytoplasmic tail. Diverse opioids induce receptor phosphorylation at S375, present in the middle of this sequence, but only high-efficacy opioids have the ability to drive higher order phosphorylation on flanking residues (T370, T376 and T379). S375 is the initiating residue in a hierarchical phosphorylation cascade. In contrast, agonist-independent heterologous μ-opioid receptor phosphorylation occurs primarily at T370. The combination of phosphosite-specific antibodies and siRNA knockdown screening also facilitated the identification of relevant kinases and phosphatases. In fact, morphine induces a selective S375 phosphorylation that is predominantly catalysed by GPCR kinase 5 (GRK5), whereas multisite phosphorylation induced by high-efficacy opioids specifically requires GRK2/3. By contrast, T370 phosphorylation stimulated by phorbol esters or heterologous activation of Gq-coupled receptors is mediated by PKCα. Rapid μ-opioid receptor dephosphorylation occurs at or near the plasma membrane and is catalysed by protein phosphatase 1γ (PP1γ). These findings suggest that there are distinct phosphorylation motifs for homologous and heterologous regulation of μ-opioid receptor phosphorylation. However, it remains to be seen to what extent different μ-opioid receptor phosphorylation patterns contribute to the development of tolerance and dependence in vivo.

LINKED ARTICLES

This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2  相似文献   
8.
International Journal of Legal Medicine - Age determination of insects collected from vertebrate remains is an essential step in estimating time since colonization as related to the post-mortem...  相似文献   
9.
10.
Highly insoluble inorganic nanoparticles can be prepared in situ by precipitation inside of aqueous nanodroplets of cosonicated inverse miniemulsions containing salts, which are readily soluble in water. If the different salt droplets are fused, a hardly soluble salt is formed in the dispersed phase with a size considerably smaller than the size of the droplets. Subsequent encapsulation of the nanoparticles into a polymer shell is achieved by an interfacial polyaddition reaction between a polyol present in the aqueous phase and a (second) monomer (2,4‐toluene diisocyanate (TDI)) in the continuous phase. The materials are studied by transmission electron microscopy, X‐ray diffraction, dynamic light scattering (DLS), and TGA.  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