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   2981篇
  免费   155篇
  国内免费   7篇
耳鼻咽喉   44篇
儿科学   123篇
妇产科学   48篇
基础医学   331篇
口腔科学   51篇
临床医学   174篇
内科学   499篇
皮肤病学   41篇
神经病学   217篇
特种医学   155篇
外科学   348篇
综合类   87篇
预防医学   200篇
眼科学   242篇
药学   352篇
中国医学   11篇
肿瘤学   220篇
  2023年   15篇
  2022年   50篇
  2021年   68篇
  2020年   27篇
  2019年   54篇
  2018年   55篇
  2017年   40篇
  2016年   59篇
  2015年   61篇
  2014年   82篇
  2013年   111篇
  2012年   195篇
  2011年   185篇
  2010年   98篇
  2009年   89篇
  2008年   120篇
  2007年   141篇
  2006年   128篇
  2005年   126篇
  2004年   119篇
  2003年   101篇
  2002年   90篇
  2001年   64篇
  2000年   72篇
  1999年   82篇
  1998年   45篇
  1997年   31篇
  1996年   37篇
  1995年   25篇
  1994年   22篇
  1993年   32篇
  1992年   69篇
  1991年   58篇
  1990年   58篇
  1989年   60篇
  1988年   32篇
  1987年   40篇
  1986年   38篇
  1985年   35篇
  1984年   33篇
  1983年   33篇
  1981年   15篇
  1980年   19篇
  1979年   23篇
  1978年   19篇
  1976年   16篇
  1974年   17篇
  1973年   35篇
  1971年   15篇
  1970年   18篇
排序方式: 共有3143条查询结果,搜索用时 0 毫秒
101.
102.
Characterization of the interleukin 3 receptor   总被引:2,自引:0,他引:2  
A variety of homobifunctional crosslinking agents have been used to gain insight into the nature of the murine interleukin 3 (mIL-3) receptor. When [125I]mIL-3 was cross-linked to receptor sites on the surfaces of intact B6SUtA1 cells with disuccinimidyl suberate (DSS), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) revealed the existence of two radiolabeled species with molecular weights of 140 (p140) and 70 (p70) kd (after subtraction of [125I]mIL-3). The relative intensities of the two bands did not change when the [125I]mIL-3 concentration was varied, confirming Scatchard results which suggested only one affinity class. However, when [125I]mIL-3 was crosslinked to intact cells and then incubated at 37 degrees C, the intensity of p140 decreased relative to p70, suggesting a conversion of p140 to p70. This conversion could be inhibited by sodium azide, methylamine, and bacitracin and could also be prevented by first boiling for 1 min in 2% SDS and 5% 2-mercaptoethanol. The putative protease that carried out this apparent conversion appeared to be associated both with plasma membranes prepared from these cells and also with solubilized receptors. Moreover, when p140, crosslinked with both dithiobis succinimidylpropionate and glutaraldehyde, was purified and reelectrophoresed under reducing conditions, p70 could be generated. N-glycanase digestion of p140 and p70 revealed a similar level of N-linked carbohydrate, which upon closer study appeared to consist of two chains, a 3-kd and an 8-kd moiety. Consistent with this data, we propose that the receptor is a 140-kd glycoprotein that is cleaved to a 70-kd surface protein upon mIL-3 binding and chemical crosslinking.  相似文献   
103.
Depression among elderly is emerging as an important public health issue in developing countries like India. Published evidence regarding the magnitude and determinants of depression among elderly hailing from urban slum is currently limited. Hence, the current study was conducted to assess magnitude of the problem and identify factors associated with depression among the elderly in an urban slum. A cross-sectional study was done to cover total of473 elderly persons from an urban slum in Bangalore, India. They were assessed for depression using Center for Epidemiologic Studies Depression scale. The overall prevalence of depression was found to be 37.8 (95 % CI = 33.43–42.16). Multivariate analysis revealed that unemployment (self or children) (odds ratio (OR) 2.6; 95 % confidence interval (CI) 1.41–4.72), illness of self (OR 2.2; 95 % CI 1.45–3.21), female gender (OR 1.9; 95 % CI 1.19–2.89), conflicts in family (OR 1.6; 95 % CI 1.03–2.43), and marriage of children or grandchildren (OR 1.6; 95 % CI 1.02–2.68) as independent risk factors. Depression among elderly is an important health issue of this area. Psychological intervention need to be provided for all elderly persons especially at the time of being diagnosed with any kind of illness. Strategies should be targeted to the females. The stressful life events need to be identified and remedial actions taken. This facility should be made available to them at the primary level of health care. There is a need to include screening of depression in our national health programs.  相似文献   
104.

Objectives

Diabetes mellitus (DM) and heart disease, among the most prevalent chronic conditions worldwide, are increasing among younger adults who are unaware of their risk status. Previous studies in the United States have shown the efficacy of screening for risk of heart disease and diabetes in a dental setting. A screening strategy was applied to facilitate early identification of individuals at increased disease risk in a single Indian dental institute.

Methods

158 patients >30 years old, with no reported heart disease or diabetes, and unaware of any increased disease risk were enrolled. Blood pressure, total cholesterol, high-density lipoprotein levels and body mass index were collected. The Framingham Risk Score (FRS) was calculated as an indication of global risk of developing a coronary heart disease (CHD) event within 10 years; hemoglobin A1c level was used to determine DM risk.

Results

Eleven percent had increased risk of heart disease (FRS >10 %) and 32 % had abnormal A1c levels (>5.7 %). At least one risk factor was present in 61 and 39 % presented with two or more risk factors. Hypertension and obesity were the most common risk factors.

Conclusions

The use of a dental setting in a developing country could serve as a resource for early identification of patients at increased risk of developing CHD and DM, yet unaware of their increased risk. The dental setting can also serve as an entry point into the medical care system by identifying asymptomatic patients at increased risk of disease and referring these individuals to a primary care provider.  相似文献   
105.
106.
Parathyroid hormone (PTH) has been a major contributor to the anabolic therapy for osteoporosis, but its delivery to bone without losing activity and avoiding adverse local effects remain a challenge. Being the natural component of bone, use of hydroxyapatite for this purpose brings a major breakthrough in synergistic anabolism. This study focuses on synthesis, characterization and evaluation of in vitro and in vivo efficacy of PTH (1-34) adsorbed hydroxyapatite nanocarrier for synergistic enhancement in the anabolic activity of PTH for bone regeneration. The negative zeta potential of this nanocarrier facilitated its affinity to the Ca2+ rich bone tissue and solubilization at low pH enhanced specific delivery of PTH to the resorption pits in osteoporotic bone. In this process, PTH retained its anabolic effect and at the same time an increase in bone mineral content indicated enhancement of the net formative effect of the PTH anabolic therapy.  相似文献   
107.
108.
Back pain is a significant health service issue in Australia and internationally. Back pain sufferers can draw upon a range of health care providers including complementary and alternative medicine (CAM) practitioners. Women are higher users of health services than men and tend to use CAM frequently for musculoskeletal conditions. However, there remain important gaps in our understanding of women’s consultation patterns with CAM practitioners for back pain. The objective of this study is to examine the prevalence of use and characteristics of women who use CAM practitioners for back pain. The method used was a survey of a nationally representative sample of women aged 60–65 years from the Australian Longitudinal Study on Women’s Health. Women consulted a massage therapist (44.1 %, n?=?578) and a chiropractor (37.3 %, n?=?488) more than other CAM practitioners for their back pain. Consultations with a chiropractor for back pain were lower for women who consulted a General Practitioner (GP) (OR, 0.56; 95 % CI 0.41, 0.76) or a physiotherapist (OR, 0.53; 95 % CI 0.39, 0.72) than for those who did not consult a GP or a physiotherapist. CAM practitioner consultations for back pain were greater for women who visited a pharmacist (OR, 1.99; 95 % CI 1.23, 3.32) than for women who did not visit a pharmacist. There is substantial use of CAM practitioners alongside conventional practitioners amongst women for back pain, and there is a need to provide detailed examination of the communication between patients and their providers as well as across the diverse range of health professionals involved in back pain care.  相似文献   
109.
Cocaine hydrolase gene transfer of mutated human butyrylcholinesterase (BChE) is evolving as a promising therapy for cocaine addiction. BChE levels after gene transfer can be 1,500-fold above those in untreated mice, making this enzyme the second most abundant plasma protein. Because mutated BChE is approximately 70 % as efficient in hydrolyzing acetylcholine as wild-type enzyme, it is important to examine the impact on cholinergic function. Here, we focused on memory and cognition (Stone T-maze), basic neuromuscular function (treadmill endurance and grip strength), and coordination (Rotarod). BALB/c mice were given adeno-associated virus vector or helper-dependent adenoviral vector encoding mouse or human BChE optimized for cocaine. Age-matched controls received saline or luciferase vector. Despite high doses (up to 1013 particles per mouse) and high transgene expression (1,000-fold above baseline), no deleterious effects of vector treatment were seen in neurobehavioral functions. The vector-treated mice performed as saline-treated and luciferase controls in maze studies and strength tests, and their Rotarod and treadmill performance decreased less with age. Thus, neither the viral vectors nor the large excess of BChE caused observable toxic effects on the motor and cognitive systems investigated. This outcome justifies further steps toward an eventual clinical trial of vector-based gene transfer for cocaine abuse.  相似文献   
110.
The PET tracer [11C]5-hydroxytryptophan ([11C]5-HTP), which is converted to [11C]5-hydroxytryptamine ([11C]5-HT) by aromatic amino acid decarboxylase (AADC), is thought to measure 5-HT synthesis rates. But can we measure these synthesis rates by kinetic modeling of [11C]5-HTP in rat? Male rats were scanned with [11C]5-HTP (60 minutes) after different treatments. Scans included arterial blood sampling and metabolite analysis. 5-HT synthesis rates were calculated by a two-tissue compartment model (2TCM) with irreversible tracer trapping or Patlak analysis. Carbidopa (inhibitor peripheral AADC) dose-dependently increased [11C]5-HTP brain uptake, but did not influence 2TCM parameters. Therefore, 10 mg/kg carbidopa was applied in all subsequent study groups. These groups included treatment with NSD 1015 (general AADC inhibitor) or p-chlorophenylalanine (PCPA, inhibitor of tryptophan hydroxylase, TPH). In addition, the effect of a low-tryptophan (Trp) diet was investigated. NSD 1015 or Trp depletion did not affect any model parameters, but PCPA reduced [11C]5-HTP uptake, and the k3. This was unexpected as NSD 1015 directly inhibits the enzyme converting [11C]5-HTP to [11C]5-HT, suggesting that trapping of radioactivity does not distinguish between parent tracer and its metabolites. As different results have been acquired in monkeys and humans, [11C]5-HTP-PET may be suitable for measuring 5-HT synthesis in primates, but not in rodents.  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