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   69066篇
  免费   4827篇
  国内免费   1261篇
耳鼻咽喉   503篇
儿科学   2041篇
妇产科学   1597篇
基础医学   5181篇
口腔科学   1434篇
临床医学   7144篇
内科学   10574篇
皮肤病学   742篇
神经病学   2664篇
特种医学   2067篇
外国民族医学   293篇
外科学   6133篇
综合类   10317篇
现状与发展   1篇
一般理论   1篇
预防医学   9473篇
眼科学   556篇
药学   7581篇
  42篇
中国医学   3693篇
肿瘤学   3117篇
  2024年   177篇
  2023年   1225篇
  2022年   2588篇
  2021年   3341篇
  2020年   2821篇
  2019年   2680篇
  2018年   2648篇
  2017年   2028篇
  2016年   1890篇
  2015年   1869篇
  2014年   7361篇
  2013年   6239篇
  2012年   4919篇
  2011年   4963篇
  2010年   5771篇
  2009年   5372篇
  2008年   3573篇
  2007年   2592篇
  2006年   1895篇
  2005年   1650篇
  2004年   1333篇
  2003年   1085篇
  2002年   821篇
  2001年   727篇
  2000年   605篇
  1999年   518篇
  1998年   427篇
  1997年   404篇
  1996年   356篇
  1995年   306篇
  1994年   308篇
  1993年   254篇
  1992年   245篇
  1991年   248篇
  1990年   181篇
  1989年   153篇
  1988年   136篇
  1987年   133篇
  1986年   109篇
  1985年   178篇
  1984年   158篇
  1983年   122篇
  1982年   110篇
  1981年   106篇
  1980年   107篇
  1979年   85篇
  1978年   87篇
  1977年   41篇
  1976年   57篇
  1973年   38篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
张格祥  王玉  苏莉 《现代预防医学》2005,32(6):593-594,597
目的:观察锌(Zn)、维生素A(VA)、维生素B2(VB2)缺乏和补充对初断乳大鼠进食量、体重的影响。方法:通过耗竭一补充方式造成初断乳大鼠的Zn、VA、VB2单独和联合缺乏模型,后强化补充相应营养素,动态检测大鼠进食量、体重的变化。结果:Zn、VA、VB2缺乏时不同程度地影响大鼠进食量、体重,以联合缺乏影响最为突出;强化补充相应营养素后,大鼠进食量、体重均得到改善,但仍达不到正常发育水平。结论:婴幼期Zn、VA、VB2缺乏或不足可影响生长发育,应充分重视婴幼儿营养。  相似文献   
92.
Two methods of separating human sperm were compared using twenty-two semen samples. The sperm were separated by a swim-up technique or by self-migration on a Percoll gradient followed by medium change. After separation, the sperm obtained were assessed for progressive motility, ATP content, energy charge index ([ATP + 0.5 ADP]/[ATP + ADP + AMP]) and morphology. In general, and especially for semen samples containing less than 20 X 10(6) sperm/ml, separation by Percoll gradient selected sperm that were superior to those separated by the swim-up technique. The relatively high energy charge index (greater than 0.8) showed that the sperm tolerated the separation conditions well. It is suggested that self-migration on a Percoll gradient should prove useful for obtaining sperm of high quality.  相似文献   
93.
A number of neurotransmitters and neuropeptides in the hypothalamus play a role in the control of food intake, metabolism, and body weight. Particularly, noradrenergic mechanisms in several areas of the hypothalamus are involved. Control of peripheral metabolism by the hypothalamus is achieved via autonomic modulation of the function of hepatocytes, adipocytes, and the endocrine cells in the islets of Langerhans. The autonomic control mechanisms ultimately lead to an appropriate shaping of blood glucose, plasma FFA, and insulin profiles to guarantee an adequate flow of nutrients under different physiological situations. Peripheral insulin and glucose can penetrate into the brain where they might affect the function of those brain structures involved in control of food intake, metabolism, and body weight.  相似文献   
94.
目的 检测非甲-非庚型肝炎患者肝组织输血传播病毒(TTV)感染状况,TTV感染与肝组织炎症程度 及与血液学指标的相关性。方法 应用免疫组织化学法检测52例非甲-非庚型肝炎患者肝组织中TTV,并经原位 杂交证实;对TTV阳性和阴性组的血液学生化指标,诸如血清丙氨酸转氨酶(ALT)、血清天冬氨酸转氨酶(AST)、血 清总胆红素(TBIL)、白蛋白(ALB)、γ 球蛋白(γ G)、凝血酶原活动度(PTA)及组织学活动指数(HAI)进行了比较。 结果 非甲-非庚型肝炎患者肝组织中TTV抗原(TTVAg)阳性15例,检出率为28.8%;阳性物质主要定位于肝细 胞浆内,呈棕黄色细小颗粒,偶见肝细胞核内有表达;TTV阳性表达细胞呈单个、散在或片簇状分布;TTVAg阳性的 组织切片经苏木素-伊红(HE)染色后,可观察到病毒性肝炎的一些病理变化,如肝细胞胞浆疏松化、气球样变、嗜酸 样变、灶性坏死、凋亡、小叶内及汇管区炎细胞浸润;从15例TTVAg阳性病例中任选10例进行TTV DNA原位杂交 检测,结果8例阳性,二者符合率80.0%;同时对5例免疫组化TTVAg阴性肝组织进行TTV DNA原位杂交检测,结 果5例均为阴性,二者符合率100%;TTVAg阳性组ALT、AST、TBIL、γ G均值均高于TTVAg阴性组,ALB、PTA 均值均低于TTVAg阴性组,但两组比较差异无统计学意义(P>0.0  相似文献   
95.
Palliative whole brain radiotherapy (WBRT) is often recommended in the management of multiple brain metastases. Allowing for WBRT waiting time, duration of the WBRT course and time to clinical response, it may take 6 weeks from the point of initial assessment for a benefit from WBRT to manifest. Patients who die within 6 weeks (‘early death’) may not benefit from WBRT and may instead experience a decline in quality of life. This study aimed to develop a prognostic index (PI) that identifies the subset of patients with lung cancer with multiple brain metastases who may not benefit from WBRT because of ‘early death’. The medical records of patients with lung cancer who had WBRT recommended for multiple brain metastases over a 10-year period were retrospectively reviewed. Patients were classified as either having died within 6 weeks or having lived beyond 6 weeks. Potential prognostic indicators were evaluated for correlation with ‘early death’. A PI was constructed by modelling the survival classification to determine the contribution of these factors towards shortened survival. Of the 275 patients recommended WBRT, 64 (23.22%) died within 6 weeks. The main prognostic factor predicting early death was Eastern Cooperative Oncology Group (ECOG) status >2. Patients with a high PI score (>13) were at higher risk of ‘early death’. Twenty-three per cent of patients died prior to benefit from WBRT. ECOG status was the most predictive for ‘early death’. Other factors may also contribute towards a poor outcome. With further refinement and validation, the PI could be a valuable clinical decision tool.  相似文献   
96.
This cross-sectional analysis evaluated the effect of age and body mass index (BMI) on Three-Factor Eating Questionnaire scores in males. Subjects (n = 60) were recruited according to BMI status. Each completed the 51-item Three-Factor Eating Questionnaire. The group was split at the median age to produce a “younger” and “older” group for statistical analysis. A 2-way between-groups analysis of variance revealed a significant main effect of BMI on disinhibition (P = .003) and hunger (P = .041) with higher levels found in overweight males compared to healthy-weight counterparts. A significant main effect of age on hunger (P = .046) demonstrated older males were less susceptible to hunger than younger males. These insights provide a better understanding of eating behavior across the male life cycle and may assist health professionals to better guide men in weight management in the light of rising overweight/obesity.  相似文献   
97.
目的 评价诊断中老年男子部分雄激素缺乏综合征(PADAM)的游离睾酮指数(FTI).方法 对129例45岁以上健康男性的FTI进行年龄相关分析.以推算的游离睾酮(CFT)值为依据,对FTI进行有效性检验.结果 男子在中老年期FTI与增龄呈明显的负相关.FTI敏感性97.78%,特异性58.33%.结论 计算简单的FTI可用于PADAM病人的筛选和随访,尤其对70岁以上男子是血清FT较为有效的参数.  相似文献   
98.
目的 观察脂肪抽吸对中心型肥胖患者代谢指标的影响。方法 筛选中心型肥胖患者30例,采用肿胀麻醉法,脂肪抽吸量在2000~2500ml;分别检测脂肪抽吸前2d和脂肪抽吸后1周、1个月、2个月、3个月的血脂、血清胰岛素、瘦素、脂联素、抵抗素,并换算出胰岛素抵抗指数(HO-MA-IR)、胰岛素敏感指数(ISI)和血糖及胰岛素下面积。结果脂肪抽吸后1个月、2个月血糖下面积及HOMA-IR均有不同程度的降低,ISI则有所升高(术后1周:P〈0.05;术后1月:P〈0.01);脂肪抽吸后血清瘦素较脂肪抽吸前显著降低(P〈0.01),抵抗素和脂联素较脂肪抽吸前亦有所变化,特别是在术后1个月时变化较为明显(P〈0.05),除血清瘦素、血糖下面积外,其余指标脂肪抽吸后3个月基本恢复原有水平。结论 脂肪抽吸对代谢指标在3个月内有一定的影响,特别是对糖代谢改善显著,但3个月后这种变化基本恢复到原有水平。  相似文献   
99.
Research suggests that end-stage renal disease patients with elevated body mass index (BMI) have superior outcomes on dialysis. In contrast, low and high BMI patients represent the highest risk cohorts for kidney transplant recipients. The important question remains concerning how to manage transplant candidates given the potentially incommensurate impact of BMI by treatment modality. We conducted a retrospective analysis of waitlisted and transplanted patients in the United States from 1990 to 2003. We constructed Cox models to evaluate the effect of BMI on mortality of waitlisted candidates and identified risk factors for rapid weight change. We then assessed the impact of weight change during waitlisting on transplant outcomes. Decline in BMI on the waiting list was not protective for posttransplant mortality or graft loss across BMI strata. Substantial weight loss pretransplantation was associated with rapid gain posttransplantation. The highest risk for death was among listed patients with low BMI (13-20 kg/m(2), adjusted hazard ratio = 1.47, p < 0.01). Approximately one-third of candidates had a change in BMI category prior to transplantation. While observed declines in BMI may be volitional or markers of disease processes, there is no evidence that candidates have improved transplant outcomes attributable to weight loss. Prospective trials are needed to evaluate the efficacy of weight loss protocols for candidates of kidney transplantation.  相似文献   
100.
幕上星形细胞肿瘤Ki-67抗原表达及其预后作用   总被引:3,自引:2,他引:1  
目的 探讨Ki-67抗原在幕上星形细胞肿瘤中的表达及其预后作用。方法 使用S-P免疫组化方法检测82例原发性幕上星形细胞肿瘤标本中Ki-67抗原的表达。单因素使用Kaplan-Meier法,多因素分析使用COX比例风险模型进行预后分析。结果Ki-67 指数在组织学分级GradeⅡ、Ⅲ、Ⅳ中分别为2.86%±1.57%,6.72%±3.95%,8.16%±3.92%(P<0.01)。单因素及多因素分析均提示Ki-67指数是独立的预后因素。在GradeⅡ中,Ki-67指数>2.5%与Grade Ⅲ中Ki-67指数≤2.5%的患者生存期差异无显著性(P>0.05);在GradeⅣ中,Ki-67指数≤2.5%与>2.5%的患者生存期有显著性差异(P<0.01)。结论 Ki-67指数随着各病理级别增高而增高;Ki-67指数>2.5%提示预后较差。在同一病理级别中,Ki-67指数不同,其预后有显著性差异。而部分不同病理级别的患者,随着Ki-67指数的不同,其生存期却无显著差异。联合组织病理检查及Ki-67指数检测有助于更精确地判断预后。  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