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   12423篇
  免费   940篇
  国内免费   40篇
耳鼻咽喉   83篇
儿科学   450篇
妇产科学   445篇
基础医学   1478篇
口腔科学   362篇
临床医学   1340篇
内科学   2968篇
皮肤病学   338篇
神经病学   859篇
特种医学   598篇
外国民族医学   3篇
外科学   1705篇
综合类   200篇
一般理论   7篇
预防医学   959篇
眼科学   413篇
药学   616篇
  1篇
中国医学   6篇
肿瘤学   572篇
  2021年   129篇
  2019年   133篇
  2018年   187篇
  2017年   151篇
  2016年   135篇
  2015年   178篇
  2014年   238篇
  2013年   370篇
  2012年   475篇
  2011年   503篇
  2010年   354篇
  2009年   311篇
  2008年   468篇
  2007年   457篇
  2006年   483篇
  2005年   503篇
  2004年   456篇
  2003年   438篇
  2002年   434篇
  2001年   438篇
  2000年   383篇
  1999年   338篇
  1998年   183篇
  1997年   170篇
  1996年   152篇
  1995年   137篇
  1994年   125篇
  1993年   140篇
  1992年   343篇
  1991年   340篇
  1990年   297篇
  1989年   334篇
  1988年   294篇
  1987年   300篇
  1986年   255篇
  1985年   231篇
  1984年   176篇
  1983年   167篇
  1982年   108篇
  1981年   112篇
  1980年   117篇
  1979年   173篇
  1978年   148篇
  1977年   128篇
  1976年   102篇
  1975年   101篇
  1974年   116篇
  1973年   115篇
  1972年   97篇
  1970年   95篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
BACKGROUND: Diagnosis of atopic dermatitis (AD) depends on clinical features because no definitive diagnostic test exists. Criteria proposed by Hanifin and Rajka (Acta Derm Venereol (Stockh) 1980; Suppl 92: 44-47) were acceptable for hospital-based studies but were found not to be suitable for field studies. A UK working party formulated clinical diagnostic criteria that could be used in both hospital and epidemiological settings. Validation studies of the criteria showed widely variable results, probably due to different clinical settings and ethnicity. AIM AND OBJECTIVE: This study was undertaken to validate Hanifin and Rajka's criteria and to assess the comparative efficacy of their criteria and the UK working party's diagnostic criteria in the diagnosis of AD in a hospital setting in North India. SUBJECTS AND METHODS: This study serially included 101 patients with AD and 48 controls of paediatric age group. The study period was from July 2003 to December 2004. RESULTS: Hanifin and Rajka's criteria (sensitivity 96%, specificity 93.75%, positive predictive value 97% (PPV) and negative predictive value (NPV) 91.84%) had a statistical advantage over the UK working party's diagnostic criteria (sensitivity 86%, specificity 95.83%, PPV 97.75% and NPV 76.67%), with a P-value < 0.005.  相似文献   
22.
23.
24.
Glucose is provided to cells by a family of glucose transport facilitators known as GLUTs. These transporters are expressed in a tissue specific manner and are overexpressed in many primary tumors of these tissues. Regulation of glucose transport facilitator expression has been demonstrated in endometrial tissue and endometrial adenocarcinoma. The following experiments were conducted to quantify and localize the expression of GLUT1 and GLUT8 in benign endometrium and compare this expression to endometrial cancer. Endometrial tissue samples were obtained from random hysterectomy specimens of patients with benign indications for surgery and endometrial cancer. Immunoblot and immunolocatization studies were performed using GLUT1 and GLUT8 specific antisera. Endometrial samples from 65 women who had undergone hysterectomy were examined (n=38 benign, n=27 malignant). A 44 and a 35.4 kDa immunoreacive species was demonstrated in endometrium and endometrial cancer for GLUT1 and GLUT8, respectively. Upregulation of GLUT1 expression was demonstrated with increasing grade of tumors (P<0.002). GLUT8 expression was increased in all tumor subtypes compared to atrophic endometrium (P<0.001). Apical localization by GLUT1 and GLUT8 was demonstrated in endometrial glands. GLUT1 and GLUT8 demonstrated diffuse intracellular localization in the cancer subtypes. GLUT1 and GLUT8 are expressed in both human endometrium and endometrial cancer. There appears to be a step-wise progression in GLUT1 and GLUT8 expression as tumor histopathology worsens. GLUT1 and GLUT8 may be important markers in tumor differentiation, as well as providing energy to rapidly dividing tumor cells.  相似文献   
25.
This study provides additional information on the psychometric properties of the Sexual Aversion Scale (SAS). Results suggest a positive relationship between sexual aversion, generalized anxiety, and history of sexual victimization. Variables such as age and religiosity were unrelated to scores on the SAS, although females reported significantly more sexual anxiety than males. The factor structure of the SAS is described and suggests that sexual aversion is a multifaceted problem with at least three and possibly four different dimensions.  相似文献   
26.
E M Brown  R Butters  C Katz  O Kifor 《Endocrinology》1991,128(6):3047-3054
We examined the effects of the polycationic antibiotic, neomycin, on the function of dispersed bovine parathyroid cells. Neomycin caused a reversible, dose-dependent inhibition of low calcium (Ca++)-stimulated PTH release, with half-maximal inhibition at 30 microM. Maximal inhibition (with 200 microM neomycin) was not additive with the suppressive effects of high (2 mM) Ca++. Neomycin also inhibited dopamine-stimulated cAMP accumulation by 90-98% at 100-200 microM, with a half-maximal effect at 40-50 microM. This action was reversible and was blocked by preincubating the cells overnight with 0.5 microgram/ml pertussis toxin. In addition to its suppressive effects on cAMP metabolism and PTH release, neomycin stimulated the accumulation of inositol phosphates and produced a transient increase in the cytosolic Ca++ concentration (Cai) in fura-2-loaded parathyroid cells. The neomycin-evoked spike in Cai persisted despite removal of extracellular Ca++, indicating that it arises from intracellular Ca++ stores. Exposure of cells to elevated magnesium (Mg++) concentrations elicited a similar spike in Cai but blocked the spike in Cai in response to subsequent addition of neomycin and vice versa. Thus, Mg++ and neomycin mobilize Ca++ from the same intracellular store(s). These results indicate that a polycation, neomycin, closely mimics the effects of polyvalent cations on parathyroid function, suggesting that both agents regulate parathyroid function via similar biochemical pathways.  相似文献   
27.
28.
29.
SUMMARY Impotence is a common symptom which can cause considerable distress to both the sufferer and his partner. The use of pharmacotherapy to improve erectile function will continue to increase as safe and effective drugs are developed. However, restoring erectile function should not be the only treatment objective. It is also essential to address personal and emotional factors in the sufferer, conflicts in his relationship with his partner, and sexual problems in his partner, all of which may be instrumental in causing or maintaining the presenting impotence. We advocate a combined approach with appropriate medical treatment and sex and couple therapy  相似文献   
30.
Noninvasive diagnosis of deep venous thrombosis has traditionally relied on detection of alterations in venous hemodynamics. Although phleborheography is among the most sensitive tests, it is inadequate for diagnosing infrapopliteal and nonocclusive proximal thrombi and for surveillance of patients at high risk for deep venous thrombosis. Venous duplex imaging is a new technique being rapidly accepted, however, without the same critical analysis given to previous diagnostic modalities. The purpose of this study is to evaluate the diagnostic acumen of venous duplex imaging compared to phleborheography and ascending phlebography in two distinct patient groups, and to determine whether patient selection, and thus the location or magnitude of thrombi have significant influence on these diagnostic tests. One hundred ten extremities in 103 patients were prospectively evaluated with venous duplex imaging, phleborheography, and ascending phlebography within the same 24-hour period. Patients were categorized into one of two groups: Diagnostic--patients evaluated because of clinical suspicion of acute deep venous thrombosis; and Surveillance--patients at high risk of postoperative deep venous thrombosis after total joint replacement, but not symptomatic. Patients in the diagnostic group had a greater frequency of deep venous thrombosis (p less than 0.001) and significantly more occluding above-knee thrombi (p = 0.054) compared to those in the surveillance group. Phleborheography detected 73% (27/37) of above-knee thrombi in the diagnostic group compared to 29% (2/7) in the surveillance group (p = 0.036). This difference was not noted with venous duplex imaging, which detected 100% of above-knee thrombi in both diagnostic and surveillance groups and 78% (7/9) of all below-knee thrombi.(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