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   6716篇
  免费   400篇
  国内免费   40篇
耳鼻咽喉   141篇
儿科学   204篇
妇产科学   67篇
基础医学   817篇
口腔科学   80篇
临床医学   623篇
内科学   1869篇
皮肤病学   91篇
神经病学   581篇
特种医学   228篇
外国民族医学   7篇
外科学   1130篇
综合类   36篇
预防医学   358篇
眼科学   63篇
药学   412篇
中国医学   6篇
肿瘤学   443篇
  2023年   36篇
  2022年   55篇
  2021年   132篇
  2020年   74篇
  2019年   135篇
  2018年   175篇
  2017年   119篇
  2016年   136篇
  2015年   172篇
  2014年   217篇
  2013年   279篇
  2012年   438篇
  2011年   434篇
  2010年   229篇
  2009年   232篇
  2008年   367篇
  2007年   367篇
  2006年   423篇
  2005年   384篇
  2004年   327篇
  2003年   342篇
  2002年   304篇
  2001年   130篇
  2000年   137篇
  1999年   122篇
  1998年   76篇
  1997年   52篇
  1996年   60篇
  1995年   40篇
  1994年   39篇
  1993年   35篇
  1992年   97篇
  1991年   86篇
  1990年   64篇
  1989年   72篇
  1988年   54篇
  1987年   83篇
  1986年   62篇
  1985年   69篇
  1984年   43篇
  1983年   43篇
  1982年   24篇
  1981年   22篇
  1979年   45篇
  1977年   21篇
  1976年   25篇
  1974年   28篇
  1973年   28篇
  1972年   21篇
  1971年   34篇
排序方式: 共有7156条查询结果,搜索用时 15 毫秒
221.
Bidens pilosa is an Asteraceae widely used in traditional medicine for the treatment of various ailments including pain and inflammation. The present work was undertaken to assess the analgesic and antiinflammatory properties of the ethyl acetate fraction of methylene chloride/methanol (1:1) extract of leaves of Bidens pilosa at the gradual doses of 50, 100 and 200 mg/kg in mice and rats, respectively. The analgesic properties of Bidens pilosa were investigated using the acetic acid writhing, hot plate, capsaicin and formalin-induced pain models. This was followed by a study of the antiinflammatory properties using carrageenan, dextran, histamine and serotonin to induce acute inflammation in rat hind paw. The extract provided a significant (p < 0.01) reduction in pain induced by all four models of nociception. It also presented significant (p < 0.05) antiinflammatory activity in all four models of acute inflammation. These results show that the ethyl acetate fraction of methylene chloride/methanol (1:1) of Bidens pilosa has both analgesic and antiinflammatory properties. The qualitative analysis of the fraction by the high-performance liquid chromatography (HPLC) fingerprint revealed the presence of two flavonoids, namely quercetin and iso-okanin, known to have antiinflammatory and antinociceptive properties, which could be responsible for the analgesic and antiinflammatory effects observed.  相似文献   
222.
223.
224.
BackgroundA surveillance program was performed in colorectal cancer (CRC) patients after surgery, to diagnose asymptomatic recurrence.AimsTo assess whether 18-FDG positron emission tomography/CT (PET/CT) improved the detection of recurrence during a 3-year follow-up.MethodsA multicentre, two-arm randomised prospective trial comparing different 36-month follow-up strategies. Complete colonoscopy was performed at baseline and after 3 years and clinical exams with imaging every 3 months. The conventional arm (A) received carcinoembryonic antigen, liver echography, and alternated between lung radiography and computed tomography (CT) scans. The experimental arm (B) received PET/CT.ResultsA total of 365 patients with colon (79.4%) or rectal cancer (20.6%), stages II (48.2%) or III (50.8%), were enroled in this study. At 36 months, intention-to-treat analysis revealed recurrence in 31 (17.2%) patients in arm A and 47 (25.4%) in arm B (p = 0.063). At 3 years, 7 of 31 relapses (22.5%) in arm A were surgically treated with curative intent, compared to 17 of 47 (36.2%) in arm B (p = 0.25). The rates of recurrence and new cancers were higher in arm B than arm A (p = 0.038).ConclusionsPET/CT follow-up every 6 months did not increase the rate of recurrence at 3 years or the rate of surgically treated recurrence compared with conventional follow-up.  相似文献   
225.
Solary  E; Bertrand  R; Kohn  KW; Pommier  Y 《Blood》1993,81(5):1359-1368
The effects of monocytic/macrophage and granulocytic differentiation induced by phorbol myristate acetate (TPA) and all-trans retinoic acid, respectively, were tested on the induction of apoptosis in human promyelocytic leukemia HL-60 cells treated with topoisomerase I and II inhibitors. Using a filter-binding assay, we observed a strong inhibition of DNA fragmentation induced by 3- and 24-hour continuous exposure to camptothecin, VP-16, VM-26, and m-AMSA in TPA- differentiated cells. The inhibition of the typical internucleosomal DNA fragmentation was confirmed by agarose gel electrophoresis. By contrast, drug-induced DNA fragmentation was not inhibited in retinoic acid-differentiated cells, and apoptosis occurred in these cells after 4 to 5 days in the absence of drug treatment. The TPA inhibitory effect was maximal after 24 hours of treatment and was correlated with differentiation, because phorbol dibutyrate ester was active, whereas 4- alpha-TPA, a nontumor promoter that does not induce differentiation, was not active. Using alkaline elution, we observed that TPA and retinoic acid differentiation were associated with changes in topoisomerase-mediated DNA breaks that were not correlated with their differential effects on drug-induced DNA fragmentation. Moreover, TPA also inhibited DNA fragmentation induced by vinblastine, cycloheximide, calphostin C, and x-rays. Using a cell-free system, we observed that DNA fragmentation was not inhibited in nuclei from TPA-differentiated cells. Rather, inhibition of apoptosis seemed to take place in the cytoplasm. We conclude that phenotypic changes associated with TPA- induced differentiation include inactivation of a cytoplasmic activity that can induce DNA fragmentation associated with apoptosis.  相似文献   
226.
227.
228.

Background

Sinonasal undifferentiated carcinoma (SNUC) is a very rare entity with a poor prognosis. Due to the lack of studies on the subject, evidence is lacking concerning its management.

Methods

A multicenter collaborative study was conducted to assess treatment strategy, oncological outcome, and prognostic factors.

Results

Definitive analyses focused on 54 patients with a majority of advanced stage; the 3‐year overall survival (OS) and 3‐year recurrence‐free survival (RFS) rates were, respectively, 62.4% and 47.8%. During the follow‐up, 18 patients (33.3%) died, 10 (18.5%) developed metastases, 7 had lymph‐node involvement (13%), and 12 (22.2%) showed recurrence or local progression. In univariate analyses, treatment modalities associated with improved RFS were induction chemotherapy (p = 0.02) and intensity‐modulated radiotherapy (p = 0.007). In the multivariate analyses, only induction chemotherapy (p = 0.047, hazard ratio [HR] = 0.39) was significantly associated with improved RFS.

Conclusion

Multimodal therapies including induction chemotherapy and intensity‐modulated radiotherapy may improve the prognosis of SNUC; surgery might improve local control. Further multicenter studies are required.
  相似文献   
229.
230.
The case of a 20 year old woman followed up since adolescence for a progressive congestive cardiomyopathy with mitral regurgitation is reported. She was reinvestigated after hospital admission for cardiac decompensation and supraventricular arrhythmias; 2D echocardiography showed signs of severe mitral regurgitation with thickened mitral leaflets prolapsing into a dilated left atrium and, above all, abnormal diastolic wall motion related to restriction of left ventricular filling with no apparent systolic dysfunction : pulsed Doppler studies confirmed the diagnosis of mitral regurgitation but also showed retrograde diastolic flow in the aortic arch (without aortic regurgitation) and in the main pulmonary artery. Angiography showed these disturbances to be due to an abnormal origin of the left coronary artery in the main pulmonary artery. Reimplantation of the left coronary in the aorta and mitral annuloplasty were justified by the poor spontaneous prognosis of this congenital abnormality which has rarely been described in adults.  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