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   2304篇
  免费   146篇
  国内免费   8篇
耳鼻咽喉   31篇
儿科学   70篇
妇产科学   97篇
基础医学   327篇
口腔科学   51篇
临床医学   197篇
内科学   517篇
皮肤病学   55篇
神经病学   213篇
特种医学   50篇
外科学   310篇
综合类   8篇
预防医学   199篇
眼科学   63篇
药学   148篇
中国医学   17篇
肿瘤学   105篇
  2023年   13篇
  2022年   23篇
  2021年   63篇
  2020年   34篇
  2019年   51篇
  2018年   70篇
  2017年   52篇
  2016年   58篇
  2015年   57篇
  2014年   82篇
  2013年   92篇
  2012年   138篇
  2011年   148篇
  2010年   83篇
  2009年   63篇
  2008年   119篇
  2007年   131篇
  2006年   117篇
  2005年   121篇
  2004年   105篇
  2003年   105篇
  2002年   101篇
  2001年   87篇
  2000年   66篇
  1999年   62篇
  1998年   14篇
  1997年   21篇
  1996年   23篇
  1995年   14篇
  1994年   12篇
  1993年   8篇
  1992年   44篇
  1991年   44篇
  1990年   30篇
  1989年   19篇
  1988年   14篇
  1987年   15篇
  1986年   20篇
  1985年   15篇
  1984年   11篇
  1982年   12篇
  1980年   7篇
  1979年   21篇
  1978年   13篇
  1977年   5篇
  1976年   7篇
  1975年   6篇
  1974年   6篇
  1969年   4篇
  1968年   4篇
排序方式: 共有2458条查询结果,搜索用时 15 毫秒
61.
62.
63.
A total of 316 samples of nasopharyngeal aspirate from infants up to two years of age with acute respiratory-tract illnesses were processed for detection of respiratory syncytial virus (RSV) using three different techniques: viral isolation, direct immunofluorescence, and PCR. Of the samples, 36 (11.4%) were positive for RSV, considering the three techniques. PCR was the most sensitive technique, providing positive findings in 35/316 (11.1%) of the samples, followed by direct immunofluorescence (25/316, 7.9%) and viral isolation (20/315, 6.3%) (p < 0.001). A sample was positive by immunofluorescence and negative by PCR, and 11 (31.4%) were positive only by RT-PCR. We conclude that RT-PCR is more sensitive than IF and viral isolation to detect RSV in nasopharyngeal aspirate specimens in newborn and infants.  相似文献   
64.
Introduction

Disruption of intestinal barrier is a key component to various diseases. Whether barrier dysfunction is the cause or effect in these situations is still unknown, although it is believed that translocation of luminal content may initiate gastrointestinal or systemic inflammatory disorders. Since trauma- or infection-driven epithelial permeability depends on Toll-like receptor (TLR) activity, inhibition of TLR signaling has been proposed as a strategy to protect intestinal barrier integrity after infection or other pathological conditions. Recently, selective serotonin recapture inhibitors including sertraline and citalopram were shown to inhibit TLR-3 activity, but the direct effects of these antidepressant drugs on the gut mucosa barrier remain largely unexplored.

Materials and methods

To investigate this, two approaches were used: first, ex vivo studies were performed to evaluate sertraline and citalopram-driven changes in permeability in isolated intestinal tissue. Second, both compounds were tested for their preventive effects in a rat model of disrupted gut barrier, induced by a low protein (LP) diet.

Results

Only sertraline was able to increase transepithelial electrical resistance in the rat colon both when used in an ex vivo (0.8 μg/mL, 180 min) or in vivo (30 mg/kg p.o., 20 days) fashion. However, citalopram (20 mg/kg p.o., 20 days), but not sertraline, prevented the increase in phospho–IRF3 protein, a marker of TLR-3 activation, in LP-rat ileum. Neither antidepressant affected locomotion, anxiety-like behaviours or stress-induced defecation.

Conclusion

Our data provides evidence to support the investigation of sertraline as therapeutic strategy to protect intestinal barrier function under life-threatening situations or chronic conditions associated with gut epithelial disruption.

  相似文献   
65.
The objective of this study was to evaluate the infectivity of Toxocara canis eggs after interacting with isolated nematophagous fungi of the species Duddingtonia flagrans (AC001) and Pochonia chlamydosporia (VC4), and test the predatory activity of the isolated AC001 on T. canis second stage larvae after 7 days of interaction. In assay A, 5000 embryonated T. canis eggs previously in contact with the AC001 and VC4 isolated for 10 days were inoculated into domestic chickens (Gallus gallus domesticus), and then these animals were necropsied to collect material (digested liver, intestine, muscles and lungs) at 3-, 7-, 14-, and 21-day intervals after inoculation. In assay A, the results demonstrated that the prior interaction of the eggs with isolated AC001 and VC4 decreases the amount of larvae found in the collected organs. Difference (p?<?0.01) was observed in the medium larvae counts recovered from liver, lung, intestine, and muscle of animals in the treated groups when compared to the animals in the control group. At the end of assay A, a percentage reduction of 87.1 % (AC001) and 84.5 % (VC4) respectively was recorded. In the result of assay B, the isolated AC001 showed differences (p?<?0.01) compared to the control group, with a reduction of 53.4 % in the recovery of L2. Through these results, it is justified to mention that prior interaction of embryonated T. canis eggs with the tested fungal isolates were efficient in reducing the development and migration of this parasite, in addition to the first report of proven predatory activity on L2.  相似文献   
66.
Although pica, the craving and purposive consumption of non‐food substances, is common among many populations, especially during pregnancy, the health consequences are not well understood. Further, very little is known about pica among Mexican populations in the United States and Mexico. Therefore, we conducted formative research to understand pica in this understudied population. Our objectives were to identify the frequency and types of pica behaviours, to understand perceived aetiologies and consequences of pica and to ascertain if the behaviour was common enough to warrant a larger study. We held nine focus group discussions (three in the Salinas Valley, California; six in Xoxocotla, Morelos, Mexico) with 76 Mexican‐born women who were currently pregnant or had delivered within the past 2 years. Earth, adobe, bean stones and ice were the most commonly reported pica substances. Twenty‐eight of the 76 participants (37%) reported ever engaging in pica; 22 participants (29%) reported doing so during pregnancy. The proportion of women reporting pica in the United States and Mexico was 43% and 34%, respectively. Women attributed pica to the overwhelming organoleptic appeal of pica substances (especially smell and texture) and to micronutrient deficiencies. Perceived consequences of unfulfilled pica cravings were birthmarks or fetal loss; fulfilled pica cravings were also thought to be generally harmful to the mother or child, with several women specifying toxic lead, pesticides or ‘worms’. In sum, pica among Mexican women is common enough to warrant a larger epidemiologic study of its sociodemographic correlates and physiological consequences.  相似文献   
67.

Objective

To compare the effects of classic progressive resistance training (PRT) versus eccentric strength-enhanced training (EST) on the performance of functional tests and different strength manifestations in the lower limb of people with multiple sclerosis (PwMS).

Design

Experimental trial.

Setting

Strength training program.

Participants

PwMS (N=52; 19 men, 33 women) belonging to MS associations from the Castilla y León, Spain.

Interventions

Participants were assigned to 1 of 2 groups: a control group that performed PRT or an experimental group that performed EST. In both groups, the knee extensor muscles were trained for 12 weeks.

Main Outcome Measures

Before and after 12 weeks of training, maximal voluntary isometric contraction and 1 repetition maximum (1RM) of the knee extensors were evaluated, as were the Chair Stand Test (CST) and Timed 8-Foot Up and Go (TUG) functional tests.

Results

No differences were found between the groups in the initial values for different tests. Intragroup comparisons found significant differences in CST (F=69.4; P<.001), TUG (F=40.0; P<.001), and 1RM (F=57.8; P<.001). For intergroup comparisons, EST presented better results than PRT in the CST (EST, 4.7%±2.8%; PRT, 1.9%±2.8%; F=13.1; P=.001) and TUG (EST, ?2.9±4.7; PRT, ?.41±5.6; F=5.6; P=.022).

Conclusions

In PwMS, EST leads to improvements in 1RM, TUG, and CST that are similar to those of PRT. However, for patients who participated in this study, the EST seems to promote a better transfer of strength adaptations to the functional tests, which are closer to daily-living activities.  相似文献   
68.
69.
70.
The present study explores the potential utility of peripheral versus central administration of glucagon-like peptide-1 (GLP-1) receptor agonists in the regulation of feeding behavior in Wistar and Zucker obese rats. Acute central (intracerebroventricular [i.c.v.]) and peripheral (subcutaneous [s.c.]) administration of both GLP-1 (7-36) amide and exendin-4 resulted in a reduction in food intake for at least 4 hours, exendin-4 being much more potent than GLP-1 (7-36) amide, especially after peripheral administration. Both Zucker obese rats (fa/fa) and their lean littermates (Fa/-) responded to acute central and peripheral administration of exendin-4. Moreover, in situ hybridization revealed specific labeling for the mRNA for GLP-1 receptors in several brain areas of both the obese and lean rats. The presence of this receptor was also detected by affinity cross-linking assays. Long-term s.c. administration of exendin-4 (1 single injection per day, 1 hour prior to the onset of the dark phase of the cycle) decreased daily food intake and practically blocked weight gain in obese rats. In contrast to previous studies, these findings show that peripheral (s.c.) administration of both GLP-1 receptor agonists also induces satiety and weight loss in rats, and suggest the potential usefulness of exendin-4 as a therapeutic tool for the treatment of diabetes and/or obesity.  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