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   11835篇
  免费   621篇
  国内免费   40篇
耳鼻咽喉   228篇
儿科学   392篇
妇产科学   219篇
基础医学   1382篇
口腔科学   317篇
临床医学   771篇
内科学   3011篇
皮肤病学   358篇
神经病学   775篇
特种医学   241篇
外国民族医学   1篇
外科学   1876篇
综合类   131篇
一般理论   4篇
预防医学   852篇
眼科学   309篇
药学   845篇
中国医学   50篇
肿瘤学   734篇
  2023年   64篇
  2022年   111篇
  2021年   330篇
  2020年   168篇
  2019年   317篇
  2018年   481篇
  2017年   267篇
  2016年   267篇
  2015年   280篇
  2014年   367篇
  2013年   511篇
  2012年   848篇
  2011年   937篇
  2010年   444篇
  2009年   377篇
  2008年   759篇
  2007年   775篇
  2006年   785篇
  2005年   719篇
  2004年   664篇
  2003年   591篇
  2002年   545篇
  2001年   211篇
  2000年   213篇
  1999年   205篇
  1998年   67篇
  1997年   52篇
  1996年   58篇
  1995年   54篇
  1994年   40篇
  1993年   25篇
  1992年   75篇
  1991年   67篇
  1990年   61篇
  1989年   61篇
  1988年   55篇
  1987年   65篇
  1986年   54篇
  1985年   46篇
  1984年   40篇
  1983年   47篇
  1982年   34篇
  1981年   29篇
  1980年   21篇
  1979年   34篇
  1978年   24篇
  1977年   21篇
  1975年   20篇
  1974年   34篇
  1973年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
ObjectiveSeveral studies have reported the association of genes related to vascular tone, hypertension, oxidative stress and preeclampsia. We investigated the possible association among three polymorphisms in eNOS (as well their haplotypes): one of MTHFR, one of GSTP1 and one of AGT, with severe preeclampsia in Mexican-Mestizo women.MethodsTwo hundred thirty women with severe preeclampsia and 350 control subjects were genotyped; for rs2070744 and rs1799983 of eNOS, rs1801133 of MTHFR, rs1695 of GSTP1 and rs699 of AGT we used real-time PCR allelic discrimination and for VNTR of eNOS, PCR. Allele frequency differences were assessed by χ2. Logistic regression was used to test for associations and for haplotype frequencies using Haploview 4.2.ResultsGenotypic and allelic distribution of the polymorphisms was similar between cases and controls; likewise, haplotype frequencies of the three polymorphisms of eNOS did not differ significantly.ConclusionsTo our knowledge, this is the first time that these polymorphisms have been analyzed together and exclusively in women with severe preeclampsia. However, we did not find an association between polymorphisms of eNOS, MTHFR, GSTP1 and AGT with severe preeclampsia in our population. Additionally, we observed differences in the distribution of the alleles and genotypes of these polymorphisms in our population in comparison to those described in other ethnic groups.  相似文献   
72.
73.
Cannabinoid agonists such as Δ9-tetrahydrocannabinol (THC) are more potent and/or efficacious antinociceptive agents in female than male rats using acute pain models. We tested the hypothesis that THC is more effective in females than males using a model of longer-lasting, inflammatory pain. THC’s anti-allodynic, anti-hyperalgesic, and anti-edema effects were examined 1, 3, and 7 days after injection of complete Freund’s adjuvant (CFA) into the hind paw. Systemically administered THC (0.32–3.2 mg/kg, intraperitoneally [i.p.], same dose each day) was significantly more effective in females than males in attenuating CFA-induced thermal hyperalgesia, but was also more sedative in females. When administered locally into the inflamed hind paw, THC (250–500 μg intraplantar, i.pl.) did not affect locomotor activity in either sex, yet produced greater anti-allodynic and anti-hyperalgesic effects in females than males. Despite THC’s greater anti-allodynic and anti-hyperalgesic effects in females, both i.p. and i.pl. THC reduced hind paw thickness (edema) more in males. The anti-hyperalgesic effect of i.p. THC was blocked by the CB1 receptor-selective antagonist rimonabant in both sexes. Similarly, i.pl. rimonabant antagonized i.pl. THC’s effects in both sexes; in contrast, the CB2 antagonist SR144528 significantly attenuated i.pl. THC’s anti-allodynic effect only in females. Intraplantar SR144528 also antagonized i.pl. THC’s anti-edema effect in males. This study suggests that cannabinoids may be better at reducing edema in males while being more effective against inflammatory pain in females. Furthermore, sex differences in THC’s peripheral effects against inflammatory pain may be a result of activation of both types of cannabinoid receptors in females, in contrast to predominantly CB1 receptors in males.  相似文献   
74.
Seventeen strains of alcoholic yeasts were screened for petite mutation frequency and killer phenotypes with an objective to develop them as industrial strains. The frequency of petite mutations varied with the strain. Though some strains have shown high frequency mutations, a few strains were found to be genetically stable. The killer property was found to vary with the strains. Interestingly, though some strains proved to be sensitive, some strains were found to be killer strains for marker killer strain also. Thus, the study provides the evidence that the killer principle varies with the strain.  相似文献   
75.
76.
77.
To investigate 1) the correlation between the proliferative activity of epididymal epithelium plus myoid cells and the increase in the number of these cells and 2) the role of the basal epithelial cells in the renewal of epididymal epithelium, a quantitative evaluation of the proliferation of both epithelial cells and periductal myoid cells in the different epididymal regions (caput, corpus, and cauda) has been carried out during postnatal development of the rat by immunohistochemical evaluation of BrdU-labeling indices. These data were correlated with cell numbers and counted by the optical dissector method. The presence of bcl-2 protein was immunohistochemically detected and evaluated. No significant differences in BrdU indices were observed among epididymal regions in any stage studied. Cell proliferation decreased from the prepubertal period to adulthood in both epithelial and myoid cells in the three regions of the epididymis, suggesting a close relationship between epithelial and mesenchymal components. The numbers of both cell types were significantly higher in the caput than in the corpus and cauda in all stages studied, suggesting functional differences between regions. A negative linear correlation between proliferative activity and cell numbers was noted that might be related to regulation of the cell population size. Basal cells showed a lower proliferation rate than principal cells, but most of the immunoreactive bcl-2 protein, in pubertal and adult epididymides, was observed in basal cells. Therefore, these cells might comprise a low-proliferating and apoptosis-resistant population.  相似文献   
78.
Staphylococcus aureus associated peritonitis and catheter exit site infections (ESI) are an important cause of hospitalization and catheter loss in the patients undergoing chronic peritoneal dialysis (PD). We aimed to determine the potential effectiveness of the application of mupirocin cream at the catheter exit site in preventing exit site infection and peritonitis. METHODS: This prospective historically controlled study was done in a total of 86 patients who entered our PD program from April 1999 to January 2001. They were instructed to apply Mupirocin cream 2% to the exit site daily or on alternate days. The patients were not screened to determine whether they were staphylococcus aureus carriers. One hundred and thirteen patients on PD prior to April 1999 acted as historical controls. Both groups were followed prospectively for a period of 22 months. RESULTS: In the study group application of mupirocin lead to a significant reduction in the incidence rate of both exit site infections overall (0.43 vs. 0.09; p<0.0001) and ESI due staphylococcus aureus (0.14 vs. 0.02; p=0.004) amounting to a relative reduction of 79% and 85% respectively. Although the overall incidence of peritonitis did not change (0.28 vs. 0.26; p=0.7) there was a significant reduction in peritonitis caused by staphylococcus aureus (0.07 vs. 0; p=0.01) Although only one catheter required removal in the mupirocin group as against 5 in the control group, this was not statistically significant. CONCLUSIONS: Mupirocin application at the exit site significantly lowers the incidence of ESI and peritonitis caused by staphylococcus aureus without any significant side effects.  相似文献   
79.
STUDY DESIGN: The 5 year review of patients referred to one center. OBJECTIVE: To report spinal cord infarction secondary to vascular occlusion from disease in a lower thoracic intervertebral foramen. METHOD: The clinical and imaging findings of two cases with acute spinal cord dysfunction are presented. SETTING: Midlands Centre for Spinal Injuries, England. RESULTS: The CT and MR imaging features revealed lower thoracic unilateral foraminal occlusion due to acute facet joint septic arthritis in a diabetic patient, and secondary to chronic hypertrophic osteophytes in a second hypertensive individual. The presumed mechanism of infarction was occlusion of the artery of Adamkiewicz. CONCLUSION: Foraminal disease in the lower thoracic levels needs to be entertained in cases of unexplained nontraumatic acute spinal cord dysfunction.  相似文献   
80.
ObjectiveTo present our centre‘s experience in the surgical treatment of lithiasis in patients with horseshoe kidney.Material and methodsFrom October 2007 to March 2011 we treated 10 patients with renal lithiasis in their horseshoe kidneys. Retrospectively, we reviewed the symptoms, medical and surgical history, the characteristics of the stones (size, location, composition) and treatments that were carried out. In all the cases, the study was carried out by CT, with volume reconstruction and with an angiographic study. A percutaneous nephrolithotomy (PCNL) or an endoscopic retrograde intrarrenal surgery (RIRS) was carried out, depending on the size and location of the stone.ResultsThree percutaneous nephrolithotomies were carried out (2 on staghorn lithiasis stones, 1 pseudocoraliform stone) with a combined rigid and flexible single-access nephroscopy. In one case there was haemorrhage that required treatment by selective embolization. In the rest, RIRS was carried out, all with stones < 30 mm in their greatest diameter without any complications. The mean surgical times were 120 (60-180) minutes for the percutaneous route and of 105 (65-160) minutes for the retrograde route. In all the cases the treatment achieved a complete elimination of the stones or remains of less than 5 mm.ConclusionsThe treatment of renal lithiasis in horseshoe kidneys is complex, given their peculiar anatomy. The usual surgical techniques can be reproduced in these cases with good results. We opt for PCNL in complete staghorn stone and pseudocoraiform stones, whereas RIRS is a valid option in cases with stones < 3 cm.  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