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   10259篇
  免费   449篇
  国内免费   200篇
耳鼻咽喉   50篇
儿科学   205篇
妇产科学   387篇
基础医学   1466篇
口腔科学   62篇
临床医学   635篇
内科学   1572篇
皮肤病学   289篇
神经病学   1208篇
特种医学   266篇
外科学   825篇
综合类   1093篇
预防医学   1280篇
眼科学   32篇
药学   916篇
  3篇
中国医学   337篇
肿瘤学   282篇
  2024年   79篇
  2023年   130篇
  2022年   239篇
  2021年   395篇
  2020年   344篇
  2019年   279篇
  2018年   221篇
  2017年   268篇
  2016年   257篇
  2015年   223篇
  2014年   453篇
  2013年   609篇
  2012年   422篇
  2011年   574篇
  2010年   436篇
  2009年   478篇
  2008年   527篇
  2007年   514篇
  2006年   427篇
  2005年   401篇
  2004年   309篇
  2003年   295篇
  2002年   278篇
  2001年   202篇
  2000年   208篇
  1999年   187篇
  1998年   148篇
  1997年   131篇
  1996年   102篇
  1995年   126篇
  1994年   129篇
  1993年   116篇
  1992年   109篇
  1991年   115篇
  1990年   93篇
  1989年   77篇
  1988年   72篇
  1987年   76篇
  1986年   87篇
  1985年   93篇
  1984年   112篇
  1983年   65篇
  1982年   60篇
  1981年   75篇
  1980年   65篇
  1979年   62篇
  1978年   60篇
  1977年   41篇
  1976年   33篇
  1975年   31篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Hypertension (HT) and the metabolic syndrome are major problems in Africa. The role of sex hormones in the cardiovascular profile of black Africans in South Africa has not been studied. Our objective was to study the association between the sex hormones and ambulatory blood pressure and the heart rate (HR) in black and white South Africans. The 24-hour ambulatory blood pressure measurements were performed and the blood samples were taken between 07:00 and 09:00 hours. A total of 80 black and 98 white South African teachers between 25 and 65 years of age from similar socioeconomic backgrounds from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study were included. As a result, a more vulnerable cardiovascular profile was observed in Africans compared with Caucasians. In the African group, low testosterone (T) explained 19%–36% of the variance in systolic blood pressure (SBP), diastolic blood pressure (DBP), and HR, whereas in the Caucasian group non-sex-hormone-binding globulin (non-SHBG)-bound T explained 27% of the variance in HR. In the African males, inverse associations between blood pressure and T (SBP: P = .08; DBP: P = .02) and non-SHBG-bound T (SBP: P < .001; DBP: P < .01) and HR (P < 0.01) were observed. Ambulatory HR predicted a prediabetic state in Africans. In conclusion, low T levels may predispose or result in impaired cardiovascular function in African men. The possibility exists that a prediabetic state, vagal-impaired HR, and hyperkinetic blood pressure responses may predispose or result in low T levels in African men.  相似文献   
53.
Abstract

The multi-factorial nature of adverse reproductive effects mediated by endocrine disrupting compounds (or EDCs) makes understanding the mechanistic basis of reproductive dysfunction a highly pertinent area of research. As a consequence, a main motivator for continued research is to integrate ‘multi-leveled’ complexity (i.e., from genes to phenotype) using mathematical methods capable of encapsulating properties of physiological relevance. In this study, an in silico stoichiometric model of piscine steroidogenesis was augmented with a ‘biomass’ reaction associating the underlying stoichiometry of steroidogenesis with a reaction representative of gonad growth. The ability of the in silico model to predict perturbed steroidogenesis and subsequent effects on gonad growth was tested by exposing reproductively active male and female fathead minnows (Pimephales promelas) to 88?ng/L of the synthetic estrogen, 17α-ethynylestradiol (EE2). The in silico model was parameterized (or constrained) with experimentally quantified concentrations of selected steroid hormones (using mass spectrometry) and fold changes in gene expression (using RT-qPCR) for selected steroidogenic enzyme genes, in gonads of male and female fish. Once constrained, the optimization framework of flux balance analysis (FBA) was used to calculate an optimal flux through the biomass reaction (analogous to gonad growth) and associated steroidogenic flux distributions required to generate biomass. FBA successfully predicted effects of EE2 exposure on fathead minnow gonad growth (%gonadosomatic index or %GSI) and perturbed production of steroid hormones. Specifically, FBA accurately predicted no effects of exposure on male %GSI and a significant reduction for female %GSI. Furthermore, in silico simulations accurately identified disrupted reaction fluxes catalyzing productions of androgens (in male fish) and progestogens (in female fish), an observation which agreed with in vivo experimentation. The analyses presented is the first-ever to successfully associate underlying flux properties of the steroidogenic network with gonad growth in fish, an approach which can incorporate in silico predictions with toxicological risk assessments.  相似文献   
54.
55.
The effect of 6-months' physical training on plasma testosterone, androstenedione and luteinizing hormone levels and the binding capacity of sex-hormone-binding globulin (SHBG capacity) were studied in thirty-nine army recruits. Highly significant increases in mean plasma testosterone (21 %), androstenedione (25%) and LH (25%) were observed during the training period and were associated with a mean 16% increase in the estimated maximal oxygen uptake. The mean increases in hormone levels tended to be greater in the well conditioned group than in the poorly conditioned group. The mean ratio of testosterone to SHBG capacity increased by 32% (P<0.05), which may be in relationship with the various training-induced effects.  相似文献   
56.
Cannabinoid agonists such as Δ9-tetrahydrocannabinol (THC) are more potent and/or efficacious antinociceptive agents in female than male rats using acute pain models. We tested the hypothesis that THC is more effective in females than males using a model of longer-lasting, inflammatory pain. THC’s anti-allodynic, anti-hyperalgesic, and anti-edema effects were examined 1, 3, and 7 days after injection of complete Freund’s adjuvant (CFA) into the hind paw. Systemically administered THC (0.32–3.2 mg/kg, intraperitoneally [i.p.], same dose each day) was significantly more effective in females than males in attenuating CFA-induced thermal hyperalgesia, but was also more sedative in females. When administered locally into the inflamed hind paw, THC (250–500 μg intraplantar, i.pl.) did not affect locomotor activity in either sex, yet produced greater anti-allodynic and anti-hyperalgesic effects in females than males. Despite THC’s greater anti-allodynic and anti-hyperalgesic effects in females, both i.p. and i.pl. THC reduced hind paw thickness (edema) more in males. The anti-hyperalgesic effect of i.p. THC was blocked by the CB1 receptor-selective antagonist rimonabant in both sexes. Similarly, i.pl. rimonabant antagonized i.pl. THC’s effects in both sexes; in contrast, the CB2 antagonist SR144528 significantly attenuated i.pl. THC’s anti-allodynic effect only in females. Intraplantar SR144528 also antagonized i.pl. THC’s anti-edema effect in males. This study suggests that cannabinoids may be better at reducing edema in males while being more effective against inflammatory pain in females. Furthermore, sex differences in THC’s peripheral effects against inflammatory pain may be a result of activation of both types of cannabinoid receptors in females, in contrast to predominantly CB1 receptors in males.  相似文献   
57.
Purpose : The primary aim was to provide experience with a functional evaluation instrument (modified Barthel index-MBI) that assures the quality of work and identify its deficiencies, familiarize our staff with the feasibility of its application on our local inpatients and educate our personnel in the field of stroke rehabilitation. The secondary aim was to collect data that are measurable and reproducible, identify specific local factors that adversely affect outcomes and serve as a feedback system to our national organizations. Methods : In this prospective/retrospective study we evaluated 80 hemiplegic patients with completed stroke, admitted to hospital during the year 1989-1990. They were assessed by a neurologist, physiatrist and physiotherapist on admission and discharge using the MBI. All patients received comprehensive inpatient rehabilitation. The study was interrupted at the beginning of the Gulf crisis. However, the data were revived and retrospectively studied in the year 1994-1995. Results : The MBI proved to be fully acceptable and easily applicable in our community. The rehabilitation staff became rapidly familiarized with its application and the reproduction of its data. The goals of rehabilitation were achieved through the reduction in the number of individuals in the more severe MBI scores and the increase in the number of individuals in the less severe ones. Significant improvements occurred in dressing of the upper and lower body, washing, grooming, care of perineum, transfer chair, toilet and walking on a level of 50 yards ( p &#104 0.0005). Conclusions : We conclude that MBI is simple, convenient, efficient, gives exact and accurate information about daily activities and ambulation and could be used in inpatient follow up sittings, in the Arab and culturally similar Middle East countries.  相似文献   
58.
超声引导下注射皮质类固醇治疗狭窄性腱鞘炎   总被引:1,自引:0,他引:1  
目的 探讨超声引导下注射皮质类固醇治疗狭窄性腱鞘炎的方法及效果。方法 38例狭窄性腱鞘炎患者,按药物注射方法的不同随机分成2组。治疗组(21例)在10-MHz超声引导下向腱鞘内腱周间隙内穿刺注射醋酸强的松龙0.6 ml,对照组(17例)采用闭合穿刺法注射等量药物。注射前及随访时(注射后3周)测定疼痛强度视觉类比评分(Visual analogue score,VAS)。结果 随访时疼痛消失率治疗组为81%、对照组为53%,VAS下降值治疗组为[(6.8±1.9)x±s,下同]对照组为(5.1±3.0)。结论超声引导下将针尖穿刺于腱鞘内腱周间隙的操作简单、准确并可实时观察药物的分布,是治疗狭窄性腱鞘炎的较好方法。  相似文献   
59.
This paper reviews the literature on colorectal cancer from a sex and gender-based perspective. Colorectal cancer is a major cause of death in the developed world, with rates increasing in developing countries. Although described by some writers as an ‘equal opportunity’ disease, it presents more risk to men than women. Both biological, or sex-linked factors, and gender-linked factors play a part in the aetiology of the disease, while gender differences in the use of screening and treatment also help shape the mortality gap between women and men for this condition. Without an appreciation of the part played by sex and gender in the risk of colorectal cancer, and without a gender-sensitive approach to screening in particular, it is possible that the mortality gap between men and women for this condition will widen in the future.  相似文献   
60.
Undifferentiated sex cord-stromal tumor in post-puberty male is extremely rare. There were only three reported cases in the literature. We reported a 19-year-old patient presented with an asymptomatic right testicular nodule with normal level of serum marker for germ cell tumor. Excisional biopsy and subsequent orchidectomy was preformed and the final pathology supported the diagnosis of undifferentiated sex cord-stromal tumor. He was then put on regular surveillance with no adjuvant therapy given. He remained disease free 18 months after the operation. A summary of the literatures and discussion on the management of this rare tumor was provided.  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