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   10357篇
  免费   484篇
  国内免费   116篇
耳鼻咽喉   55篇
儿科学   249篇
妇产科学   300篇
基础医学   1134篇
口腔科学   138篇
临床医学   762篇
内科学   2588篇
皮肤病学   274篇
神经病学   1021篇
特种医学   413篇
外科学   1881篇
综合类   28篇
一般理论   1篇
预防医学   342篇
眼科学   141篇
药学   648篇
中国医学   27篇
肿瘤学   955篇
  2024年   16篇
  2023年   79篇
  2022年   235篇
  2021年   294篇
  2020年   187篇
  2019年   216篇
  2018年   289篇
  2017年   200篇
  2016年   264篇
  2015年   341篇
  2014年   420篇
  2013年   555篇
  2012年   853篇
  2011年   814篇
  2010年   539篇
  2009年   437篇
  2008年   709篇
  2007年   722篇
  2006年   643篇
  2005年   630篇
  2004年   600篇
  2003年   479篇
  2002年   453篇
  2001年   59篇
  2000年   46篇
  1999年   51篇
  1998年   91篇
  1997年   60篇
  1996年   61篇
  1995年   55篇
  1994年   63篇
  1993年   45篇
  1992年   44篇
  1991年   49篇
  1990年   34篇
  1989年   35篇
  1988年   32篇
  1987年   26篇
  1986年   28篇
  1985年   17篇
  1984年   33篇
  1983年   24篇
  1982年   16篇
  1981年   12篇
  1980年   12篇
  1979年   7篇
  1978年   12篇
  1977年   8篇
  1974年   8篇
  1969年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Cardiovascular Drugs and Therapy - The purpose of the present study was to compare the long-term effectiveness and safety of newly initiated anticoagulation with edoxaban (EDO) versus uninterrupted...  相似文献   
92.
The long-term changes of liver stiffness (LS) in patients who achieve viral clearance after direct-acting anti-HCV therapy remain undefined. We conducted a multicentre prospective study to investigate this aspect. Patients with HCV infection treated with DAAs were enrolled from six Italian centres; they underwent clinical, biochemical, ultrasound and transient elastography evaluations before treatment (T0), 12 weeks (SVR12) and 24 months (T24) after the end of therapy. Among the 516 consecutive patients enrolled, 301 had cirrhosis. LS significantly decreased from T0 to SVR (14.3 vs 11.1 kPa, p = .002), with a progressive reduction until T24 (8.7 kPa, p < .001). However, only patients with steatosis and those who developed HCC did not experience a late improvement in LS. Multivariate analysis of baseline and follow-up variables identified steatosis as the only independent predictor of failure of LS improvement (OR 1.802, p = .013). ROC curve analysis of the association of LS with the risk of developing HCC showed that SVR12 ≥14.0 kPa had the highest accuracy (sensitivity 82%, specificity 99%; AUC: 0.774). Multivariate analysis revealed that LS was the only variable independently associated with an increased risk of developing HCC (OR 6.470, p = .035). Achieving an SVR was associated with a progressive, long-term decline of LS, suggesting a late improvement in liver fibrosis, besides the resolution of inflammation. Fatty liver and the development of HCC interfered with late reduction of LS. Patients with an LS ≥14 kPa at 12 weeks after the end of treatment were at higher risk for developing HCC.  相似文献   
93.
Purpose

To compare the accuracy of Contrast-Enhanced Spectral Mammography (CESM), MG, US, and breast MRI in estimating the size of breast lesions requiring surgery. The postoperative histology size of the lesion was used as the gold standard.

Material and methods

Two hundred thirty-three non-benign lesions in 189 patients were included in the analyses. All the selected patients underwent CESM and at least one other conventional diagnostic exam (US, MG, or MRI). Subsequently, all the patients underwent surgery preceded by cytological/histological examination. The largest diameter of the lesion at imaging was measured by a radiologist with more than 10 years’ experience and then compared with the size of the lesion in the histological sample at the surgery (gold standard).

Results

Among the 233 breast lesions, 196 were evaluated with US, 206 with MG and 160 with MRI. We found no statistically significant differences between size measurements using CESM and MRI compared with the measurements at the surgery (p value 0.63 and 0.51), whereas a significant difference was found for MG and US (p?<?0.001).

Conclusion

CESM is a reliable method for estimating the size of breast lesions: its performance seems superior to US and MG and comparable to MRI.

  相似文献   
94.
BACKGROUND: In cross-sectional studies, it was demonstrated that the therapeutic effect of mesalazine is closely related to its mucosal concentration. AIM: This study was carried out to verify in a longitudinal study if it was possible to improve the clinical course of ulcerative colitis at high risk of recurrence by increasing mucosal mesalazine concentration. METHODS: Eighteen consecutive ulcerative colitis patients on continuous oral 5-ASA treatment (2.4-3.2 g/day) in clinical remission who had had at least four moderate to severe relapses in the preceding 2 years (referred period) were assigned to assume oral (3.2-4.8 g/day) and topical (4 g/day) mesalazine in order to increase mucosal drug concentration and were followed up for 2 years (study period). The localisation of disease was 12 pancolitis, six left colitis. The number and severity of recurrences, number of visits and endoscopies, courses of steroids and days of hospitalisation were compared with those of the previous 2 years. Rank signed test for paired data was used for statistical analysis. RESULTS: The total number of recurrences was significantly lower during the study period in comparison with that of referred period (8 versus 80, respectively, p < 0.0001). No courses of steroids or hospitalisation were necessary during study period in comparison with those of referred period (0 versus 33, p < 0.0001; 0 versus 93, p = 0.03, respectively). A total number of 249 visits were done during the referred period and 116 during the study period (p < 0.0001) with a total of 87 endoscopies during referred period and 44 during study period (p < 0.0001). CONCLUSIONS: The continuous use of topical mesalazine associated with a high oral dosage significantly improves the clinical course of ulcerative colitis patients at high risk of relapse.  相似文献   
95.
96.
97.
We studied the correlation between dexamethasone (Dex) induced growth effects and modulation of epidermal growth factor receptor (EGFR) expression in OVCA 433 ovarian cancer cells. These cells express specific high and low affinity 125I-EGF binding sites and are growth stimulated by EGF. Dex exhibits mitoinhibitory effects by recruiting OVCA 433 cells in the G0-G1 phase of the cycle, but increases the number of both the high and the low affinity EGFR in a dose dependent manner. The maximal EGFR expression increase occurs after 24 h of Dex treatment consistently with Northern blot studies. The mitogenic activity of EGF in OVCA 433 cells is not affected by the presence of Dex. Moreover Dex growth inhibition occurs in JA1 cells, an ovarian cancer cell line which expresses unfunctional EGFR and which is unresponsive to EGF. Our results indicate that the Dex induced growth effects occur independently of EGFR expression.  相似文献   
98.
99.
100.
Candida guilliermondii (teleomorph Meyerozyma guilliermondii) is an ascomycetous species belonging to the Saccharomycotina CTG clade which has been studied over the last 40 years due to its biotechnological interest, biological control potential and clinical importance. Such a wide range of applications in various areas of fundamental and applied scientific research has progressively made C. guilliermondii an attractive model for exploring the potential of yeast metabolic engineering as well as for elucidating new molecular events supporting pathogenicity and antifungal resistance. All these research fields now take advantage of the establishment of a useful molecular toolbox specifically dedicated to C. guilliermondii genetics including the construction of recipient strains, the development of selectable markers and reporter genes and optimization of transformation protocols. This area of study is further supported by the availability of the complete genome sequence of the reference strain ATCC 6260 and the creation of numerous databases dedicated to gene ontology annotation (metabolic pathways, virulence, and morphogenesis). These genetic tools and genomic resources represent essential prerequisites for further successful development of C. guilliermondii research in medical mycology and in biological control by facilitating the identification of the multiple factors that contribute to its pathogenic potential. These genetic and genomic advances should also expedite future practical uses of C. guilliermondii strains of biotechnological interest by opening a window into a better understanding of the biosynthetic pathways of valuable metabolites.  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