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   8687篇
  免费   577篇
  国内免费   39篇
耳鼻咽喉   290篇
儿科学   224篇
妇产科学   124篇
基础医学   1303篇
口腔科学   241篇
临床医学   657篇
内科学   1549篇
皮肤病学   60篇
神经病学   547篇
特种医学   284篇
外国民族医学   1篇
外科学   1664篇
综合类   65篇
一般理论   6篇
预防医学   594篇
眼科学   725篇
药学   403篇
中国医学   5篇
肿瘤学   561篇
  2023年   104篇
  2022年   154篇
  2021年   263篇
  2020年   162篇
  2019年   258篇
  2018年   251篇
  2017年   202篇
  2016年   213篇
  2015年   205篇
  2014年   311篇
  2013年   375篇
  2012年   527篇
  2011年   480篇
  2010年   307篇
  2009年   274篇
  2008年   438篇
  2007年   461篇
  2006年   405篇
  2005年   394篇
  2004年   359篇
  2003年   336篇
  2002年   343篇
  2001年   187篇
  2000年   178篇
  1999年   154篇
  1998年   82篇
  1997年   54篇
  1996年   61篇
  1995年   61篇
  1994年   58篇
  1993年   46篇
  1992年   93篇
  1991年   96篇
  1990年   84篇
  1989年   77篇
  1988年   87篇
  1987年   81篇
  1986年   64篇
  1985年   78篇
  1984年   54篇
  1983年   41篇
  1979年   38篇
  1978年   35篇
  1933年   31篇
  1930年   34篇
  1928年   33篇
  1927年   33篇
  1926年   34篇
  1925年   41篇
  1924年   37篇
排序方式: 共有9303条查询结果,搜索用时 9 毫秒
1.
2.
3.
OBJECTIVES: Diagnostic accuracy of the ThinPrep process (Cytyc, Boxborough, MA) was compared with that of conventional (smear) cytopreparation for fine-needle aspiration (FNA) of head and neck masses. METHODS: In a prospective, randomized, single-blinded study, 209 patients served as their own controls and underwent 236 FNAs using ThinPrep and conventional (smear) cytopreparatory techniques. RESULTS: ThinPrep produced less air-drying artifact and less mechanical distortion than the conventional method. The conventional technique was diagnostic in 63% of samples; the ThinPrep technique was diagnostic in 55% of samples. When all results were combined, pathologists subjectively preferred the conventional technique but accepted use of ThinPrep as the only cytopreparatory technique for most head and neck masses. CONCLUSIONS: For adequately experienced cytopathologists, ThinPrep is acceptable for FNA of salivary masses, neck cysts, metastatic lymph nodes, and thyroid lesions. Conventional smear technique should be used for FNA of nonmetastatic lymphoid lesions. Use of ThinPrep can complement use of the conventional (smear) cytopreparatory technique when aspirate is nondiagnostic or bloody, when the patient has a blood-borne infectious disease, when the clinician is inexperienced, or when aspirate has entered the syringe.  相似文献   
4.
Can carotid endarterectomy be justified? No   总被引:1,自引:0,他引:1  
  相似文献   
5.

Background  

Despite a decreasing incidence of peptic ulcer disease, most previous studies report a stabile incidence of ulcer complications. We wanted to investigate the incidence of peptic ulcer complications in Sweden before and after the introduction of the proton pump inhibitors (PPI) in 1988 and compare these data to the sales of non-steroid anti-inflammatory drugs (NSAID) and acetylsalicylic acid (ASA).  相似文献   
6.
We have studied the intratumor HER-2/neu heterogeneity in 78 consecutive and population-based primary invasive breast carcinomas. Within the invasive component, heterogeneity was detected in only 1 of 78 tumors. In 48 tumors (62%), we found both in situ and invasive components in analyzed tissue sections. Twelve of these 48 tumors had a difference of at least 2 arbitrary units in the in situ compared with the invasive part of the tumor with regard to the HER-2/neu status analyzed by HercepTest (immunohistochemistry). Eight of these 12 tumors were reanalyzed with fluorescent in situ hybridization and immunohistochemistry with and without a new Automated Cellular Imaging System. In this limited material, immunohistochemistry in combination with the Automated Cellular Imaging System seemed to have a better correlation with fluorescent in situ hybridization than immunostaining analyzed manually. In conclusion, HER-2/neu expression is not seldom heterogeneous in invasive compared with in situ components within a tumor. This finding should be considered in the choice of evaluation method. To avoid heterogeneity as a confounding factor in HER-2/neu analyses, detection methods such as immunohistochemistry and fluorescent in situ hybridization, which can provide evaluation in a preserved tissue architecture, should be used. Perhaps the intratumor HER-2/neu heterogeneity can explain some of the unexpected failures of trastuzumab therapy.  相似文献   
7.
J Ramon  B Goldwasser  G Raviv  P Jonas  M Many 《Cancer》1991,67(10):2506-2511
From 1974 to 1983, simple and radical nephrectomies were performed at the Chaim Sheba Medical Center (Tel Hashomer, Israel) for renal cell carcinoma. The authors reviewed 109 cases that were followed for a period ranging from 5 to 14 years. Simple nephrectomy was performed in 55 patients, and 54 patients underwent radical nephrectomy. The selection of the surgical procedure was based on the surgeon's preference and not on the basis of clinical stage, age, or sex. The surgical results and survival rates were assessed according to the pathologic stage of the tumors. Among patients with Stage I tumor, radical nephrectomy produced better survival rates at 5 and 10 years (P = 0.03); however, when the non-cancer deaths were excluded, the difference in survival was not statistically significant. For Stage I tumors the survival free of disease at 5 years was better for the radical nephrectomy group, but this difference was not statistically significant. No difference was noticed in the local recurrence rate between the two groups. Nephrectomy in patients with Stage IV disease did not alter survival regardless of the type of operation.  相似文献   
8.
Five ileal conduit biopsies, taken after 1-7 years, were examined by light microscopy and scanning electron microscopy. The total height of the lamina mucosa decreased from 700 to 275 microns. The height of the villi diminished from 550 to 50 microns; the depth of the crypts increased from 130 to 244 microns and the villus-crypt index changed from 4.2 to 0.2. Signs of chronic inflammation could be observed. Scanning electron microscopy shows that the number of microvilli per cell was markedly reduced. There was a varied picture of different stages of atrophy. After 3 years microvilli could no longer be observed. In view of the prolonged urinary contamination time, it appears to be imperative to check neobladders with regard to possible carcinoma induction.  相似文献   
9.
The diameter of the temporal superior and inferior retinal artery and vein were measured at the optic disk border and 2 mm from the disk center in 264 nonselected normal eyes on the basis of photographs, with correction of magnification. Additionally, the individual ocular magnification factor was determined by Littmann's method. The mean caliber of the artery was 0.113 +/- 0.019 mm at the disk border and 0.118 +/- 0.023 2 mm from the disk center. The corresponding values for the vein were 0.149 +/- 0.026 mm and 0.159 +/- 0.026 mm. The correlations between vessel caliber and disk size were not significant, but the relationship between disk size and the quotient of vessel diameter divided by disk size was highly significant (p less than 0.0001). Vessel diameter can therefore be taken as an independent unit for determining optic disk size in relative and approximately also in absolute units. Thus, mean horizontal disk diameter (1.77 +/- 0.33 mm) corresponded to 16.3 +/- 3.5 artery and 12.3 +/- 2.6 vein diameters (measured at the optic disk border). The mean individual ocular magnification factor was 0.302 +/- 0.017, with a Gauss standard distribution. If the optical characteristics of a photographed eye are not known and the ocular magnification factor is assumed to be 0.302, then 68.3% of all eyes will be covered with an inaccuracy of 5.6% and 95.5% of all eyes with an inaccuracy of 11.2%.  相似文献   
10.
To determine the influence of the duration of postoperative lumbar immobilization with the aid of a rigid lumbar orthosis on the consolidation of posterolateral lumbosacral fusions, 22 patients with no previous osseous spinal surgery and with fusion without osteosynthesis due to spondylolysis-olisthesis Grade 1 to 2 or intervertebral disc or facet joint disorder were examined by roentgen stereophotogrammetric analysis in supine and erect positions and by conventional radiography for 1 year after surgery. In Series 1, patients (n = 11) were instructed to keep the trunk straight with the aid of a molded, rigid lumbar orthosis for 5 months after surgery; and in Series 2 (n = 11), the same instructions were given, but for 3 months. In Series 1, osseous fusion was seen on radiographs in eight patients. In these patients, the intervertebral translations between the fused vertebrae began to decrease 3-6 months after surgery, and within 1 year, the fusions became rigid, as defined by roentgen stereophotogrammetric analysis, or intervertebral translations of mostly less than 1 mm persisted. In three patients with poor fusion still seen on radiographs 1 year after surgery, no rigid fusion was obtained and intervertebral translations of up to 10 mm persisted. In Series 2, a similar roentgen stereophotogrammetric analysis pattern was noted in two patients with osseous fusion and in seven with poor fusion seen on radiographs. The fusion was radiographically doubtful in two patients. In these patients, the intervertebral translations decreased, but translations of 1.5 mm persisted 1 year after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)  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