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   3398篇
  免费   154篇
  国内免费   25篇
耳鼻咽喉   65篇
儿科学   58篇
妇产科学   27篇
基础医学   473篇
口腔科学   51篇
临床医学   206篇
内科学   983篇
皮肤病学   79篇
神经病学   209篇
特种医学   89篇
外科学   583篇
综合类   3篇
预防医学   61篇
眼科学   45篇
药学   174篇
中国医学   5篇
肿瘤学   466篇
  2023年   21篇
  2022年   32篇
  2021年   62篇
  2020年   25篇
  2019年   37篇
  2018年   48篇
  2017年   56篇
  2016年   65篇
  2015年   70篇
  2014年   90篇
  2013年   96篇
  2012年   159篇
  2011年   173篇
  2010年   107篇
  2009年   108篇
  2008年   213篇
  2007年   207篇
  2006年   200篇
  2005年   210篇
  2004年   224篇
  2003年   236篇
  2002年   229篇
  2001年   63篇
  2000年   70篇
  1999年   97篇
  1998年   62篇
  1997年   61篇
  1996年   45篇
  1995年   34篇
  1994年   29篇
  1993年   28篇
  1992年   46篇
  1991年   49篇
  1990年   27篇
  1989年   36篇
  1988年   31篇
  1987年   23篇
  1986年   18篇
  1985年   15篇
  1984年   15篇
  1983年   25篇
  1982年   14篇
  1981年   13篇
  1980年   12篇
  1979年   11篇
  1978年   13篇
  1977年   9篇
  1976年   7篇
  1973年   13篇
  1969年   7篇
排序方式: 共有3577条查询结果,搜索用时 15 毫秒
141.
The present study was designed to provide a systemic analysis of prognosis in 62 patients who underwent hepatic resection for colorectal liver metastasis. The analyzed factors included microvessel counts stained by CD34 and expression of two adhesion molecules, E-cadherin and CD44 variant exon 6-(v6) in these tumors. No significant factors related to recurrence were identified and only negative expression of CD44v6 tended to correlate with recurrence (P = 0.075). A short disease-free period to recurrence was noted in patients with high CEA levels (>10 ng/ml) and H2/3 classification. A short surgical margin, H2/3 classification, high microvessel counts (>60/field, x200), and negative expression of CD44v6 and E-cadherin tended to be associated with poor prognosis. A high microvessel count was the most significant prognostic factor by multivariate Cox proportional hazards regression model. Hepatic resection without tumor exposure and a careful follow-up in cases identified with poor prognostic factors are necessary.  相似文献   
142.
143.
144.
Since sentinel lymph node(SLN) biopsy has a higher negative predictive value than that of four-node sampling, SLN biopsy might become the new acknowledged standard of clinical care for patients with early breast cancer. SLN biopsy is widely used in Western countries despite the lack of data from randomized trials. Clinical practice guidelines document that SLN biopsy should be performed with prudent informed consent and thorough surgical technique. Before surgeons replace axillary dissection with SLN biopsy as the staging procedure at their institution, they should perform backup axillary dissection until a detection rate of more than 90% and a false-negative rate of less than 5% are achieved. Recently, SLN biopsy has more often been indicated for multicentric breast cancer, larger tumors, prior excisions, and noninvasive carcinoma. While SLN biopsy is widely used in Western countries, there is little experience in Japan. If randomized studies, clinical practice guidelines, and the coverage of lymphoscintigraphy under health insurance were introduced, SLN biopsy would be used more widely in Japan.  相似文献   
145.
Purpose. Vascular endothelial growth factor C (VEGF-C) is known to be associated with the development of the lymphatic vessel system. Recently, VEGF-C is thought to be correlated with lymph node metastasis in some malignant tumors. In this study, we investigated the correlation between VEGF-C expression and lymph node metastasis in early carcinoma of the colon and rectum. Methods. Two hundred and twenty-one endoscopically biopsied specimens from patients with T1 colorectal carcinoma prior to operation were investigated by an immunohistochemical study. Results. VEGF-C expression was more frequently observed in the tumors with nodal metastasis than in those without metastasis. Moreover, a multivariate analysis indicated that VEGF-C expression is an independent predictor of lymph node metastasis. Conclusion. VEGF-C staining using endoscopically biopsied specimens prior to operation could be of use in the prediction of lymph node metastasis and in preoperative selection of treatment in patients with T1 colorectal carcinoma.  相似文献   
146.
Purpose Our purpose was to study the characteristics of colorectal neoplasms in patients with gastric cancer (GC). Methods The study group comprised GC patients who underwent colonoscopy before resection of their GC. We examined the prevalence, site, and histology of colorectal neoplasms, as well as the clinicopathological features and treatment of the patients who had synchronous colorectal cancers (CRC). The logistic regression model was applied to investigate the features of the GC patients with concurrent CRC. Results We studied 466 GC patients (mean age 64.5 years; 147 women, 319 men), 143 (31%) of whom had a family history of gastrointestinal cancer. Synchronous colorectal adenoma and cancer were detected in 182 (39%) and 18 (4%) patients, respectively. Among the 18 synchronous CRCs, 11 were in the early stages and 10 of these were resected endoscopically. The other eight required simultaneous open radical surgery. All the GC patients with synchronous CRC were older than 50 years. Statistical analysis did not show a significant difference between the features of the patients with and those without concurrent CRC. Conclusions The possibility of synchronous colorectal neoplasms in GC patients cannot be disregarded in clinical practice; however, screening of the large bowel may not be necessary in GC patients younger than 50 years.  相似文献   
147.
We report a patient with cystic lymphangiomas diagnosed by endoscopic ultrasonography and resected by partial polypectomy. A 42-year-old woman consulted a nearby physician because of a positive fecal occult blood test. Barium enema and colonoscopy revealed the presence of abnormalities. On March 11, 1997, she was admitted to our department for further evaluation and treatment. A barium enema examination revealed two protruding lesions in the transverse colon. Colonoscopy showed a teardrop-type mass in the left side of the transverse colon. The mass was cushion-sign positive, and its shape readily changed on respiration and with changes in body position. Another superficial smooth mass was found in the right side of the transverse colon. Ultrasonography of the colon confirmed the presence of a submucosal mass showing a cyst-like pattern. Cystic lymphangiomas were diagnosed and resected endoscopically. Histopathological examination revealed markedly dilated ducts consisting of a single layer of endothelial cells in the submucosa of the colon. The diagnosis was cystic lymphangioma. Received: June 22, 1998 / Accepted: February 26, 1999  相似文献   
148.
Cyclic nucleotides (cAMP and cGMP) phosphodiesterase (PDE) activities and expression are altered in the cardiac muscle of cardiomyopathic heart failure, and PDE inhibitors improve the abnormal muscle condition through changing the cyclic nucleotide concentration. These observations prompted us to investigate the role of calmodulin (CaM) in the regulation of cyclic nucleotide PDE activities, and moreover to study the modulation of the PDE isozymes in heart failure, using cardiac muscles of cardiomyopathic hamster. The CaM concentrations in the heart muscle of the normal control and cardiomyopathic hamsters (each of three to four hamsters) varied with cell fraction and with the age of the animal. The CaM concentrations in the soluble fraction obtained from cardiomyopathic hamster tissue were significantly increased at 25 and 32 weeks of age (2.02 +/- 0.62 microg/mg protein (mean +/- S.E.), and 3.21 +/- 0.95) compared with that obtained from the control (0.60 +/- 0.04) or cardiomyopathic (0.95 +/- 0.12) hamsters at 8 weeks of age. The solubilized PDE isolated from the hamster heart muscle (three or four hamsters in each age) by column chromatography on diethylaminoethyl (DEAE)-cellulose revealed three peaks of activity, which may correspond to the isozymes of PDE classified recently, namely PDE I, II, and III. These three peaks of activity, particularly peak III, seen in the soluble fraction of cardiomyopathic hamster heart declined in proportion to the age of the animal compared with that of the control hamster heart. In the cGMP-PDE assay system, the concentration of CaM inhibitor W-7 required for 50% inhibition (IC(50)) of PDE I, II, and III peak activities was 140, 29, and 46 microM, respectively, suggesting that PDE II is more sensitive to W-7. These results suggest that alteration in these isozyme activities accompanied with changes of CaM concentration may influence the cardiac muscle contractility in cardiomyopathic hamster via changes of cyclic nucleotide concentration.  相似文献   
149.
Monitoring minimal residual disease (MRD) in patients with acute lymphoblastic leukemia (ALL) is a useful way for assessing treatment response and relapse. We studied the value of MRD and showed a correlation with relapse for 34 adult patients with ALL. MRD was evaluated by real-time quantitative polymerase chain reaction (RQ-PCR) with probes derived from fusion chimeric genes (BCR/ABL) (n = 12) or PCR-based detection of clonal immunoglobulin and T cell receptor gene rearrangements (n = 16), or both (n = 6). We analyzed 27 of the 34 patients who could be examined for MRD on day 100 after induction therapy. The overall survival (OS) rate (45.0%) and relapse-free survival (RFS) rate (40.0%) at 2 years in complete remission (CR) patients with MRD level ≥10?3 (n = 12) were significantly lower than those in CR patients with MRD level <10?3 (n = 15) (OS rate 79.0%, RFS rate 79.4%) (log-rank test, P = 0.017 and 0.0007). We also applied multicolor flow cytometry for comparison with MRD results analyzed by PCR methods. The comparison of results obtained in 27 follow-up samples showed consistency in 17 samples (63.0%) (P = 0.057). MRD analysis on day 100 is important for treatment decision in adult ALL.  相似文献   
150.
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