全文获取类型
收费全文 | 3770篇 |
免费 | 251篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 143篇 |
妇产科学 | 143篇 |
基础医学 | 618篇 |
口腔科学 | 20篇 |
临床医学 | 228篇 |
内科学 | 683篇 |
皮肤病学 | 112篇 |
神经病学 | 152篇 |
特种医学 | 255篇 |
外科学 | 378篇 |
综合类 | 264篇 |
一般理论 | 2篇 |
预防医学 | 283篇 |
眼科学 | 120篇 |
药学 | 391篇 |
1篇 | |
中国医学 | 39篇 |
肿瘤学 | 215篇 |
出版年
2023年 | 14篇 |
2022年 | 37篇 |
2021年 | 59篇 |
2020年 | 28篇 |
2019年 | 46篇 |
2018年 | 63篇 |
2017年 | 39篇 |
2016年 | 57篇 |
2015年 | 75篇 |
2014年 | 104篇 |
2013年 | 156篇 |
2012年 | 260篇 |
2011年 | 278篇 |
2010年 | 148篇 |
2009年 | 130篇 |
2008年 | 197篇 |
2007年 | 192篇 |
2006年 | 194篇 |
2005年 | 177篇 |
2004年 | 159篇 |
2003年 | 147篇 |
2002年 | 121篇 |
2001年 | 108篇 |
2000年 | 106篇 |
1999年 | 85篇 |
1998年 | 87篇 |
1997年 | 62篇 |
1996年 | 56篇 |
1995年 | 47篇 |
1994年 | 49篇 |
1993年 | 44篇 |
1992年 | 65篇 |
1991年 | 54篇 |
1990年 | 44篇 |
1989年 | 61篇 |
1988年 | 48篇 |
1987年 | 45篇 |
1986年 | 56篇 |
1985年 | 48篇 |
1984年 | 27篇 |
1983年 | 22篇 |
1982年 | 28篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1978年 | 21篇 |
1977年 | 22篇 |
1976年 | 20篇 |
1975年 | 18篇 |
1973年 | 15篇 |
排序方式: 共有4061条查询结果,搜索用时 15 毫秒
51.
0 引言 人类免疫缺陷病毒 (human immunodeficiencyvirus,HIV) - 1编码的反式激活蛋白 TAT具有独特的跨膜运转方式 ,而且有转导速度快 ,效率高的特点 ,被称为蛋白转导结构域 (protein transduction domain,PTD) [1 ,2 ] .本研究用PCR扩增了慢性粒细胞白血病慢粒 bcr/ abl融合蛋白的基因片段 ,在其 5′端融合 PTD结构域的编码区后在大肠杆菌中进行了表达 .表达产物经纯化后 ,加入培养的 HL 6 0细胞 ,表达的蛋白可直接进入细胞内 .这一结果为用外源蛋白负载(L oading)免疫细胞提供了新的途径 .1 材料和方法1.1 DNA重组 人工合… 相似文献
52.
Subacute (90 days) oral toxicity studies of Kombucha tea 总被引:4,自引:0,他引:4
Vijayaraghavan R Singh M Rao PV Bhattacharya R Kumar P Sugendran K Kumar O Pant SC Singh R 《Biomedical and environmental sciences : BES》2000,13(4):293-299
Kombucha tes(KT) is a popular health beverage and is used as an alternative therapy,KT is prepared by placing the kombucha culture in solution of tea and sugar and allowing to ferment,The inoculum is a fungus consisting of symbiotic colony of yeast and bacteria.KT is consumed in several coutries and is believed to have prophylactic and therapeutic benefits in a wide variety of ailments,viz.,intestinal disorders,arthritis,ageing and stiumulation of immunological system.Though KT is used in several parts of the world its eneficial effects and adverse effects have not been scientifically evaluated.Since there are no animal toxicological data on KT,subacute oral toxicity study was carried out.Five goups of rats were maintained:(a) control group given tap water orally,(b) KT given 2ml/kg orally,(c)plain tea(PT) given 2ml/kg orally,(d)KT given in drinking water,1%(v/v)and (e)PT given indrinking water,1%(v/v).The rats were given this treatment daily for a period of 90 days,Weekly records of weight,feed intake,water intake and general behaviour were monitored.There was no significant difference in the growth of the animals as evidenced by the progrssive body weight change.The organ to body weight ration and histologuical evaluation did not show any toxic signs.The haematological and biochemical variables,were within the clinical limits.The study indicates that rats fed KT for 90 day showed no toxic effects. 相似文献
53.
beta-Tethymustine, 1-[2- {bis(2'-chloroethyl)amino}ethyl]spiro[imidazolidine-4,2'-(1'H),3',4'-dihydronaphthalene]-2,5-dione, has been synthesised and LD50 value determined in Swiss male mice, which was found to be 100.00 mg/kg by single i.p. injection. The following three criteria, namely ascites cell count, ascites fluid measurement and increase in median survival times (MST) of drug-treated (T) over untreated control (C) mice, were studied for evaluation of its antitumour efficacy in vivo in three murine ascites tumours, namely Ehrlich ascites carcinoma (EAC), sarcoma-180 (S-180) and Dalton's lymphoma (DL). At the optimum dose range of 8.0 mg/kg (higher) to 4.0 mg/kg (lower) for 1-7 days treatment following tumour transplantation on day 0, it exhibited a very high percentage of inhibition of both the ascites cell and fluid in these models and displayed excellent ILS(max) value of 80 in EAC, 224 in S-180 and 240 in DL, respectively, showing 'curative' effect (2-3/6 mice having 90 days survival rate). It also demonstrated a high ILS value of 150 with one cure/six mice bearing S-180 for 6 days prior to drug therapy. Screening results were compared with two clinical drugs, cyclophosphamide and 5-fluorouracil, serving as positive controls. Its chemical alkylating activity was compared with nor-HN2 (NSC 10873) and spiromustine (NSC 172112). The results indicate that it possesses greater alkylating activity than nor-HN2 and comparable activity with spiromustine. 相似文献
54.
Apomorphine (10 mg/kg, s.c.) does not induce in mice a compulsion to gnaw, but pretreatment with cocaine (10–40 mg/kg, i.p.) caused gnawing activity. This effect of cocaine was inhibited by pretreatment with -methyl-p-tyrosine, haloperidol, and physostigmine, but not with FLA-63, phenoxybenzamine and tetrabenazine. These findings would suggest that dopaminergic mechanism plays a significant role in the potentiation of apomorphine gnawing activity by cocaine and also support the view that inhibition of dopamine uptake is responsible for the stimulatory action of cocaine. 相似文献
55.
MRI of the intraorbital optic nerve in patients with autosomal dominant optic atrophy 总被引:3,自引:0,他引:3
Votruba M Leary S Losseff N Bhattacharya SS Moore AT Miller DH Moseley IF 《Neuroradiology》2000,42(3):180-183
Measurements of the intraorbital optic nerve were made using high-resolution coronal MRI in 10 adults with autosomal dominant
optic atrophy. Comparisons were made with previous studies of 10 normal adult subjects. The cross-sectional diameters of the
optic nerve and the perineural subarachnoid space were measured and a ratio of there diameters at anterior, mid and posterior
positions along the optic nerve was determined. We found a statistically significant difference in the mean optic nerve: sheath
ratio between the control group and patients with autosomal dominant optic atrophy. At anterior, mid and posterior locations
along the optic nerve it is significantly smaller in patients with optic atrophy. We have demonstrated that the loss of ganglion
cells, previously documented in dominant optic atrophy, is associated with a significant loss of optic nerve tissue and thinning
of the nerve along its length.
Received: 6 July 1999/Accepted: 22 July 1999 相似文献
56.
目的观察小分割分次立体定向放射治疗(fractionated stereotatic radiation therapy,FSRT)脑转移瘤的近期疗效.方法15例病人单纯全脑外照射(WBRT组),中间平面剂量20~40Gy/10~20次/2~4周.17例病人接受FSRT(FSRT组),每次分次剂量为2.5~3.0Gy.其中11病人行单纯FSRT,中心总剂量为30~60Gy/1 0~20次/2~4周;6例病人先行WBRT,然后行FSRT,中心总剂量为46~60Gy/5~6周.结果KSP评分增加10分以上者,WBRT组为5 3.3%,FSRT组为82.4%.(P<0.05).WBRT组有效率(CR PR)为50.0%;FSRT组有效率(CR PR)为80.0%.中位生存率:WBRT组为3.5月,FSRT组为10.0月.结论FSRT能有效地控制脑转移瘤,减轻神经系统症状,提高生存质量,延长病人生存期,而没有增加副作用,值得临床推广应用. 相似文献
57.
We compared the tumor-initiating activities toward mouse skin of two
structurally related polycyclic aromatic hydrocarbon diol epoxides: racemic
anti-1,2,3,4-tetrahydro-5,6-dimethylchrysene-1,2-diol-3,4- epoxide
(5,6-diMeCDE) and racemic anti-1,2,3,4-tetrahydro-5-
methylchrysene-1,2-diol-3,4-epoxide (5-MeCDE). Tumors induced by these diol
epoxides were analysed for mutations in the Ha-ras gene. 5,6- diMeCDE is
derived from the non-planar parent compound 5,6- dimethylchrysene, and
reacts to approximately equal extents with dA and dG in DNA, whereas
5-MeCDE is derived from a nearly planar parent compound, 5-methylchrysene,
and reacts mainly with dG in DNA. 5,6- diMeCDE, at initiating doses of 33,
100 or 400 nmol per mouse, induced 1.2, 2.2 and 6.2 skin tumors per mouse,
respectively. It was significantly less tumorigenic than 5-MeCDE which
induced 3.1, 7.5 and 9.1 skin tumors per mouse at the same doses. Tumors
induced by 5,6- diMeCDE had a large number of CAA-->CTA mutations in
codon 61 of the Ha- ras gene: 50, 55 and 75% of the tumors analysed had
this mutation at the 33, 100 and 400 nmol doses. No mutations were found in
codons 12 and 13 in the tumors induced by 5,6-diMeCDE. In contrast,
CAA-->CTA mutations in codon 61 were rarely seen in tumors induced by
5-MeCDE. At the highest dose of 5-MeCDE, 20% of the tumors analysed had
mutations at G of codons 12 and 13. The results of this comparative study
support the hypothesis that mutations in the Ha-ras gene in mouse skin
tumors induced by PAH diol epoxides occur as a result of their direct
reaction with the gene. However, pathways other than the commonly observed
Ha- ras codon 61 mutations are clearly important in mouse skin
tumorigenesis by these diol epoxides.
相似文献
58.
Evoked potential monitoring in anaesthesia and analgesia 总被引:4,自引:0,他引:4
Electrophysiological monitoring of selected neural pathways of the brain, brainstem, spinal cord and peripheral nervous system has become mandatory in some surgery of the nervous system where preventable neural injury can occur. Evoked potentials are relatively simple methods of testing the integrity of various aspects of the nervous system. This review covers the variety of evoked potentials that can be monitored and outlines the principles of their measurement. Their use in specific situations and how factors such as anaesthesia might affect them is presented. 相似文献
59.
Impacts of Informal Caregiver Availability on Long-term Care Expenditures in OECD Countries
下载免费PDF全文
![点击此处可从《Health services research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Byung-Kwang Yoo Jay Bhattacharya Kathryn M. McDonald Alan M. Garber 《Health services research》2004,39(6P2):1971-1992
Objective. To quantify the effects of informal caregiver availability and public funding on formal long-term care (LTC) expenditures in developed countries.
Data Source/Study Setting. Secondary data were acquired for 15 Organization for Economic Cooperation and Development (OECD) countries from 1970 to 2000.
Study Design. Secondary data analysis, applying fixed- and random-effects models to time-series cross-sectional data. Outcome variables are inpatient or home heath LTC expenditures. Key explanatory variables are measures of the availability of informal caregivers, generosity in public funding for formal LTC, and the proportion of the elderly population in the total population.
Data Collection/Extraction Method. Aggregated macro data were obtained from OECD Health Data, United Nations Demographic Yearbooks, and U.S. Census Bureau International Data Base.
Principal Findings. Most of the 15 OECD countries experienced growth in LTC expenditures over the study period. The availability of a spouse caregiver, measured by male-to-female ratio among the elderly, is associated with a $28,840 (1995 U.S. dollars) annual reduction in formal LTC expenditure per additional elderly male. Availability of an adult child caregiver, measured by female labor force participation and full-time/part-time status shift, is associated with a reduction of $310 to $3,830 in LTC expenditures. These impacts on LTC expenditure vary across countries and across time within a country.
Conclusions. The availability of an informal caregiver, particularly a spouse caregiver, is among the most important factors explaining variation in LTC expenditure growth. Long-term care policies should take into account behavioral responses: decreased public funding in LTC may lead working women to leave the labor force to provide more informal care. 相似文献
Data Source/Study Setting. Secondary data were acquired for 15 Organization for Economic Cooperation and Development (OECD) countries from 1970 to 2000.
Study Design. Secondary data analysis, applying fixed- and random-effects models to time-series cross-sectional data. Outcome variables are inpatient or home heath LTC expenditures. Key explanatory variables are measures of the availability of informal caregivers, generosity in public funding for formal LTC, and the proportion of the elderly population in the total population.
Data Collection/Extraction Method. Aggregated macro data were obtained from OECD Health Data, United Nations Demographic Yearbooks, and U.S. Census Bureau International Data Base.
Principal Findings. Most of the 15 OECD countries experienced growth in LTC expenditures over the study period. The availability of a spouse caregiver, measured by male-to-female ratio among the elderly, is associated with a $28,840 (1995 U.S. dollars) annual reduction in formal LTC expenditure per additional elderly male. Availability of an adult child caregiver, measured by female labor force participation and full-time/part-time status shift, is associated with a reduction of $310 to $3,830 in LTC expenditures. These impacts on LTC expenditure vary across countries and across time within a country.
Conclusions. The availability of an informal caregiver, particularly a spouse caregiver, is among the most important factors explaining variation in LTC expenditure growth. Long-term care policies should take into account behavioral responses: decreased public funding in LTC may lead working women to leave the labor force to provide more informal care. 相似文献
60.