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   4264篇
  免费   211篇
  国内免费   27篇
耳鼻咽喉   18篇
儿科学   54篇
妇产科学   39篇
基础医学   414篇
口腔科学   88篇
临床医学   257篇
内科学   1217篇
皮肤病学   114篇
神经病学   305篇
特种医学   126篇
外科学   703篇
综合类   7篇
预防医学   84篇
眼科学   69篇
药学   197篇
中国医学   11篇
肿瘤学   799篇
  2023年   30篇
  2022年   36篇
  2021年   90篇
  2020年   60篇
  2019年   66篇
  2018年   100篇
  2017年   100篇
  2016年   108篇
  2015年   91篇
  2014年   131篇
  2013年   144篇
  2012年   276篇
  2011年   293篇
  2010年   187篇
  2009年   166篇
  2008年   261篇
  2007年   323篇
  2006年   282篇
  2005年   299篇
  2004年   301篇
  2003年   250篇
  2002年   287篇
  2001年   51篇
  2000年   36篇
  1999年   44篇
  1998年   55篇
  1997年   45篇
  1996年   37篇
  1995年   35篇
  1994年   24篇
  1993年   30篇
  1992年   32篇
  1991年   21篇
  1990年   25篇
  1989年   33篇
  1988年   26篇
  1987年   14篇
  1986年   14篇
  1985年   14篇
  1984年   10篇
  1983年   5篇
  1982年   8篇
  1981年   7篇
  1980年   10篇
  1979年   5篇
  1978年   7篇
  1977年   6篇
  1976年   4篇
  1973年   5篇
  1971年   4篇
排序方式: 共有4502条查询结果,搜索用时 15 毫秒
101.
A 47-year-old man was admitted for follow-up of an abnormal chest x-ray. He had a history of epistaxis and a brain abscess and a family history of pulmonary arteriovenous fistulas. Physical examination showed clubbed fingers and telangiectasia of the tongue. Laboratory data revealed evidence of polycythemia and hypoxia. Contrast echocardiography and pulmonary perfusion scintigraphy were suggestive of a right-to-left shunt. From the oxygen tension and content of blood taken at cardiac catheterization, the shunt ratio was calculated to be 57.8%. Multiple bilateral pulmonary arteriovenous fistulas were confirmed by angiography, and the patient was diagnosed as having hereditary hemorrhagic telangiectasia. A review of x-ray films taken over a 24-year period demonstrated that the fistulas in both lungs had been increasing gradually in size at different rates. A right lower lobectomy relieved the hypoxia, but the patient died unexpectedly on the twelfth postoperative day. There was no evidence of fistula rupture on chest film, but no autopsy was performed.  相似文献   
102.
Observing the entire circumference of the hypopharynx is usually difficult because most of the area is anatomically closed in the resting state. The modified Killian's method, consisting of a combination of the modified Killian position, head torsion, and the Valsalva maneuver, is a recently proposed procedure to improve the endoscopic view of the hypopharynx. A fish bone, which was invisible under regular endoscopy but was identified by CT, was successfully observed and removed under the modified Killian's method in a 71-year-old female. This method can be applied to diagnose and treat benign hypopharyngeal disease such as fish bone foreign body in addition to the detection of cancer.  相似文献   
103.
104.

Background

N-Acetylglucosaminyltransferase V (GnT-V), an enzyme that catalyzes the β1-6 branching of N-acetylglucosamine on asparagine-linked oligosaccharides of cellular proteins, enhances the malignant behaviors of carcinoma cells in experimental models. The aim of this study was to determine clinical significance of GnT-V expression in human pT2 gallbladder carcinoma with simple in vitro experiments.

Methods

Ninety patients with pT2 gallbladder carcinoma were included for this study. The in vitro and in vivo biological effects of GnT-V were investigated using gallbladder carcinoma cells with variable GnT-V expression levels induced by a small interfering RNA.

Results

Of the 90 cases, 57 showed positive staining and the remaining 33 demonstrated negative staining, the subcellular localization in the 57 cases was classified into the granular-type in 31 cases and the diffuse-type in 26 cases. In 76 cases with curative resection, postsurgical survival was significantly poorer in those showing positive staining than in those showing negative staining (P = 0.028). In all of the 76 cases, postsurgical recurrence was significantly more frequent in those showing diffuse-type localization than in those showing negative staining. Experimental analyses demonstrated that the down-regulation of GnT-V expression in gallbladder carcinoma cells induced suppression of cell growth in vitro. The expression levels of GnT-V in the cells were highly correlated with the rapid in vivo growth coupled with the enhanced angiogenesis, and the tendency to form liver metastasis.

Conclusions

GnT-V expression in the subserosal layer of pT2 gallbladder carcinoma is correlated with the aggressiveness of the disease.  相似文献   
105.
This study sought to demonstrate the feasibility of estimating the source strength during implantation in brachytherapy. The requirement for measuring the strengths of the linked sources was investigated. The utilized sources were 125I with air kerma strengths of 8.38–8.63 U (μGy m2 h–1). Measurements were performed with a plastic scintillator (80 mm × 50 mm × 20 mm in thickness). For a source-to-source distance of 10.5 mm and at source speeds of up to 200 mm s–1, a counting time of 10 ms and a detector-to-needle distance of 5 mm were found to be the appropriate measurement conditions. The combined standard uncertainty (CSU) with the coverage factor of 1 (k = 1) was ∼15% when using a grid to decrease the interference by the neighboring sources. Without the grid, the CSU (k = 1) was ∼5%, and an 8% overestimation due to the neighboring sources was found to potentially cause additional uncertainty. In order to improve the accuracy in estimating source strength, it is recommended that the measurment conditions should be optimized by considering the tradeoff between the overestimation due to the neighboring sources and the intensity of the measured value, which influences the random error.  相似文献   
106.
107.
108.
Burns are a common type of skin injury encountered at all levels of medical facilities from private clinics to core hospitals. Minor burns heal by topical treatment alone, but moderate to severe burns require systemic management, and skin grafting is often necessary also for topical treatment. Inappropriate initial treatment or delay of initial treatment may exert adverse effects on the subsequent treatment and course. Therefore, accurate evaluation of the severity and initiation of appropriate treatment are necessary. The Guidelines for the Management of Burn Injuries were issued in March 2009 from the Japanese Society for Burn Injuries as guidelines concerning burns, but they were focused on the treatment for extensive and severe burns in the acute period. Therefore, we prepared guidelines intended to support the appropriate diagnosis and initial treatment for patients with burns that are commonly encountered including minor as well as moderate and severe cases. Because of this intention of the present guidelines, there is no recommendation of individual surgical procedures.  相似文献   
109.
110.
This paper shows how protonated 3,4-ethylene dioxythiophene moieties can be used as an end group to make organic conductors. An organic semiconductor 2,5-bis(5-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene is designed and synthesized. This molecule could be doped by protonic acid in both solution and solid-state, resulting in a broad absorption in the near-infrared range corresponding to polaron and bipolaron absorption. Electrical conductivity of ca. 0.1 S cm−1 was obtained at 100 °C (to avoid the water uptake by the acid). The adducts with protons bound at the end-thiophene α-position were confirmed by 1H Nuclear Magnetic Resonance spectra.

The use of protonated 3,4-ethylenedioxythiophene moieties as an end group could be a promising approach to prepare organic conductors.  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