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   182331篇
  免费   11968篇
  国内免费   1260篇
耳鼻咽喉   2366篇
儿科学   3856篇
妇产科学   4448篇
基础医学   26935篇
口腔科学   3654篇
临床医学   18082篇
内科学   34459篇
皮肤病学   4619篇
神经病学   14588篇
特种医学   8389篇
外科学   23564篇
综合类   2414篇
现状与发展   5篇
一般理论   127篇
预防医学   12609篇
眼科学   4672篇
药学   15075篇
中国医学   1625篇
肿瘤学   14072篇
  2023年   1187篇
  2022年   2971篇
  2021年   5279篇
  2020年   2801篇
  2019年   4113篇
  2018年   4974篇
  2017年   3682篇
  2016年   4649篇
  2015年   6153篇
  2014年   7667篇
  2013年   9442篇
  2012年   14180篇
  2011年   13894篇
  2010年   8116篇
  2009年   6899篇
  2008年   10576篇
  2007年   10578篇
  2006年   9825篇
  2005年   9324篇
  2004年   8451篇
  2003年   7399篇
  2002年   6503篇
  2001年   4545篇
  2000年   4150篇
  1999年   3416篇
  1998年   1533篇
  1997年   1181篇
  1996年   1093篇
  1995年   997篇
  1994年   854篇
  1993年   769篇
  1992年   1652篇
  1991年   1646篇
  1990年   1417篇
  1989年   1300篇
  1988年   1208篇
  1987年   1081篇
  1986年   1053篇
  1985年   932篇
  1984年   697篇
  1983年   632篇
  1982年   474篇
  1981年   440篇
  1980年   408篇
  1979年   562篇
  1978年   447篇
  1977年   427篇
  1976年   387篇
  1974年   397篇
  1973年   371篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Younis M  Vivian A  Lee JP 《Strabismus》1995,3(2):85-88
Background: The Fells modification of the Harada-lto procedure is usually performed bilaterally for the correction of excyclotorsion secondary to acquired bilateral superior oblique paresis. Excyclotorsion is not usually a major complaint in true unilateral superior oblique paresis. Occasional cases, however, may find this symptom bothersome and it may interfere with fusion. The purpose of the present study is to determine the effect of the unilateral modified Harada-lto procedure on the correction of symptomatic excyclotorsion in unilateral superior oblique paresis. Method: A retrospective case-note review of patients with unilateral superior oblique paresis undergoing unilateral modified Harada-lto procedures during the five-year period 1988-1993 was performed. Results: Six patients fulfilled the inclusion criteria. Superior oblique paresis was congenital in one case, secondary to trauma in two cases and idiopathic acquired in three cases. There were four males and two females aged from 25 to 63 years and all but one had previous surgery. The mean pre-operative excyclotorsion was approximately 10 degrees (range 8-14 degrees). Mean post-operative excyclotorsion was 3 degrees (range 2 degrees incyclotorsion -10 degrees excyclotorsion). Conclusion: The unilateral modified Harada-lto procedure is an effective surgical treatment of excyclotorsion resulting from superior oblique paresis and may improve sensory and motor fusion.  相似文献   
993.
BACKGROUND: Orbital apex syndrome due to aspergillus sphenoid sinusitis is a rare condition. Human immunodeficiency virus (HIV) infection has recently been reported in aspergillus orbital abscess. To the authors' knowledge this is the first reported association of HIV with the orbital apex syndrome. METHODS: A 37-year-old HIV-infected man presented with headache, reduced vision and progressive ophthalmoplegia in the right eye. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed sphenoid sinusitis. Sphenoid sinus biopsy was performed. RESULTS: Light microscopy revealed infiltrative branching septate fungal hyphae. Fungal culture isolated Aspergillus fumigatus. CONCLUSION: Atypical fungal infection such as Aspergillus fumigatus sphenoid sinusitis should be suspected in HIV-infected patients with orbital apex syndrome.  相似文献   
994.
Automation technology offers great potential in pharmacy practice. To realize the full benefits of the potential inherent in automation systems, it is necessary to understand basic concepts of automation and to realize that automation is simply a tool to help achieve the goals of practice. The goal of pharmacy practice is pharmaceutical care. Through using the techniques of reengineering, pharmacies can be redesigned with the help of automation to facilitate the accomplishment of that goal. Essential to achieving that goal is the necessity to change the focus of pharmacy from distribution to pharmaceutical care. Reengineering and automation are the tools to help make that change in focus.  相似文献   
995.
996.
54 sporadic colorectal cancers were analyzed for aberrations in the K-ras oncogene. DNA was extracted from frozen tissues obtained from surgical resection and analyzed for mutations in codons 12, 13 and 61 of the K-ras oncogene using single strand conformation polymorphism analysis (SSCP) and direct sequencing. Point mutations in the K-ras oncogene were found in 26/54 (48%) cases, all of which resulted in amino acid substitutions. No other types of mutations (e.g. insertions or deletions) were found. 4 of the mutations were at codon 12, 22 in codon 13 and only 1 was a codon 61 mutant. G-->A transitions were found to be predominant. A remarkable finding was the high preponderance of (13)Gly-(13)Ser mutations (54%). No correlation was observed between K-ras mutations and tumor location, Dukes' stage, differentiation levels, age or sex of the patient.  相似文献   
997.
Transgenic mice have been used to demonstrate that the myc transgene, fused to the murine mammary tumor virus LTR promoter, leads to development of mammary tumors. To study the role of the Myc protein in these tumors, a sensitive immunohistochemical method was used to compare the Myc protein expression in mammary tumors and normal mammary gland from two independent MTV/myc transgenic lines. The highest levels of staining for Myc were found in the epithelial cell nuclei of mammary tumors and foci of mammary hyperplasia. Normal transgenic epithelium had only scattered foci of low intensity staining nuclei. The nuclei of transgenic mesenchyme and of non-transgenic mammary glands of control FVB mice did not contain detectable antigen. This work supports the hypothesis that the Myc protein can play a role in mammary tumorigenesis and suggests a correlation between high levels of Myc and the development of histopathology.  相似文献   
998.
Vomiting is a common, unpleasant aftermath of tonsillectomy in children. Intraoperative intravenous ondansetron (OND) reduces vomiting after this operation. Our doubleblind, placebocontrolled, randomized investigation studied the effect of the oral form of OND on vomiting after outpatient tonsillectomy in children. We studied 233 healthy children age 2–14 yr undergoing elective tonsillectomy. Subjects were given placebo (PLAC) or OND 0.1 mg · kg?1 rounded off to the nearest 2 mg one hr before surgery. Anaesthesia was induced with either propofol or halothane/N2O. Vecuronium 0.1 mg · kg?1 was administered at the discretion of the anaesthetist. Anaesthesia was maintained with halothane/N2O, 50 μg · kg?1 midazolam iv and 1–1.5 mg · kg?1 codeine im. At the end of surgery, residual neuromuscular blockade was reversed with neostigmine and atropine. All episodes of inhospital emesis were recorded by nursing staff. Rescue antiemetics in the hospital were 1 mg · kg?1 dimenhydrinate ivfor vomiting × 2 and 50 μg · kg?1 droperidol iv for vomiting × 4. Parents kept a diary of emesis after discharge. Postoperative pain was treated with morphine, codeine and/or acetaminophen. The two groups were similar with respect to demographic data, induction technique and anaesthesia time. Oral OND (n = 109) reduced postoperative emesis from 54% to 39%, P < 0.05. This effect was most dramatic inhospital, where 10% of the OND-patients and 30% of the PLAC-group vomited, P < 0.05. The OND-subjects required fewer rescue antiemetics, 7% vs 17%, P < 0.05. In conclusion, oral ondansetron decreased the incidence of vomiting after outpatient tonsillectomy in children.  相似文献   
999.
Background: Tumor growth and metastases require the development of new vessels (angiogenesis). Angiogenesis, assessed by microvessel count using immunocytochemical stain of endothelial cells, has been shown to predict metastases and correlate with early death. Recently developed color Doppler mapping can detect the “tumor flow signals” in breast cancer and help to distinguish it from benign lesions. The question is, does this tumor vascularization assessed by color Doppler mapping correlate with the angiogenesis assessed by immunocytochemistry? Methods: Eighty-four patients admitted for breast surgery were studied. The final diagnosis was made by pathology for 52 malignancies and 32 benign lesions. The color Doppler mapping of the breast lesion was made preoperatively. The following parameters were assessed: (a) vessel location (peripheral or central); (b) density of color Doppler signals; and (c) maximum systolic velocity. Tumor angiogenesis was assessed by microvessel count under light microscopy using the platelet/endothelial cell adhesion molecule antibodies (CD31) method. The correlation between maximum velocity and microvessel count of breast cancer was examined. The clinical significance of maximum flow velocity of breast cancer with various clinicopathologic factors was assessed. Results: Color signals were detected in 48 cases of 52 malignancies (92%). All tumors demonstrated signals at the periphery of the lesion but in only 13 (27%) were the signals detected within the tumor. Color signals were scored as + + or + + + in 44 (92%) patients. Pulsed wave blood flow was shown in all these 48 tumors, with maximum velocities varying from 4 to 36 cm/s. Among the 32 benign lesions, color signals were detected in 10 (31%) and all were peripheral and scored subjectively as +. Evaluation of these color Doppler mapping parameters shows no significant correlation with microvessel counts using CD31 monoclonal antibodies. However, there was a positive association (p<0.05) between nodal metastases and higher tumor flow velocity in T1 (<2 cm) breast tumors but not in larger tumors. Conclusion: Although the color Doppler mapping has been shown to be useful in distinguishing benign from malignant breast lesions, the intensity of signal and velocity of flow had no correlation with the extent of angiogenesis of breast cancer. The presence of high-flow tumor signal in early breast carcinoma is significantly associated with the presence of axillary lymph node metastases.  相似文献   
1000.
Work-related assault injuries among nurses.   总被引:2,自引:0,他引:2  
Work-related violence is a major public health problem; however, there is a serious deficiency in the knowledge of risk factors for this problem. The purpose of this case-control study was to identify risk factors for work-related assault injuries among nurses. We used unconditional logistic regression to model the dependence of work-related assault injuries on each exposure of interest and the respective confounders. We found a decreased rate for the presence of security personnel (RR = 0.40; 95% CI = 0.19-0.82). We found increased rates for the following factors: the perception that administrators considered assault to be part of the job (RR = 8.14; 95% CI = 3.76-17.60); having received assault prevention training in the current workplace (RR = 4.64; 95% CI = 2.33-9.23); a high (>5) vs. low (<2) patient/personnel ratio (RR = 2.54; 95% CI = 1.13-5.70); working predominantly with patients with mental illness (RR = 3.5; 95% CI = 1.41-8.85); and working with patients who had more than 1- to 4-week and more than 4-week lengths of stay in the institution vs. <1 day (RR = 8.85; 95% CI = 1.58-49.52 and 4.25; 95% CI = 1.17-15.39, respectively).  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