全文获取类型
收费全文 | 70535篇 |
免费 | 3720篇 |
国内免费 | 306篇 |
专业分类
耳鼻咽喉 | 1446篇 |
儿科学 | 2312篇 |
妇产科学 | 1612篇 |
基础医学 | 9112篇 |
口腔科学 | 2425篇 |
临床医学 | 4807篇 |
内科学 | 17362篇 |
皮肤病学 | 2363篇 |
神经病学 | 5683篇 |
特种医学 | 1495篇 |
外国民族医学 | 1篇 |
外科学 | 8511篇 |
综合类 | 477篇 |
一般理论 | 21篇 |
预防医学 | 7168篇 |
眼科学 | 1295篇 |
药学 | 4948篇 |
中国医学 | 467篇 |
肿瘤学 | 3056篇 |
出版年
2023年 | 518篇 |
2022年 | 1360篇 |
2021年 | 2696篇 |
2020年 | 1265篇 |
2019年 | 2338篇 |
2018年 | 2742篇 |
2017年 | 1629篇 |
2016年 | 1568篇 |
2015年 | 1754篇 |
2014年 | 2647篇 |
2013年 | 3658篇 |
2012年 | 5122篇 |
2011年 | 5465篇 |
2010年 | 3072篇 |
2009年 | 2584篇 |
2008年 | 3879篇 |
2007年 | 4037篇 |
2006年 | 3733篇 |
2005年 | 3775篇 |
2004年 | 3405篇 |
2003年 | 3118篇 |
2002年 | 2825篇 |
2001年 | 1607篇 |
2000年 | 1750篇 |
1999年 | 1444篇 |
1998年 | 465篇 |
1997年 | 412篇 |
1996年 | 311篇 |
1995年 | 286篇 |
1994年 | 240篇 |
1993年 | 182篇 |
1992年 | 530篇 |
1991年 | 431篇 |
1990年 | 416篇 |
1989年 | 313篇 |
1988年 | 316篇 |
1987年 | 283篇 |
1986年 | 251篇 |
1985年 | 239篇 |
1984年 | 148篇 |
1983年 | 148篇 |
1982年 | 115篇 |
1981年 | 125篇 |
1980年 | 96篇 |
1979年 | 143篇 |
1978年 | 109篇 |
1974年 | 105篇 |
1971年 | 88篇 |
1969年 | 87篇 |
1968年 | 75篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Generoso Gómez Cruz Miguel Barrueco Ferrero Irene Aparicio Coca José Ángel Maderuelo Miguel Torrecilla García 《Archivos de bronconeumologia》2009,45(1):16-23
Background and ObjectiveSchool smoking prevention programs have never yielded the expected results. The aim of this study was to analyze the efficacy of an intensive smoking prevention program created by the educational community in which it was to be applied.Population and MethodA 3-year smoking prevention program was carried out among the students of Fuentesaúco Secondary School in Zamora, Spain. The Babilafuente Secondary School in Salamanca, Spain was the control group. The program included both prevention and treatment activities. The former were carried out in the school, in out-of-school situations, and in the community. The questionnaire of the European Smoking Prevention Framework Approach was used.ResultsA total of 417 students aged 12 to 17 years participated in the study. Of these, 54.4% belonged to the intervention group and 45.6% to the control group. Smokers represented 36.7% of the population. After the intervention smokers represented 40.1% of the Fuentesaúco students compared with 46.1% of the Babilafuente students, though the difference was not statistically significant. With respect to the cognitive determinants of smoking behavior, after the intervention significant differences in favor of the intervention group were only observed in the subjects’ perception of the behavior of their siblings, peers, and teachers.ConclusionsThe use of smoking prevention programs in schools should be reconsidered, and their evaluation should be based on educational rather than clinical criteria. Proposed changes in the program include decreasing its intensity, starting with students of an earlier age and seeking greater involvement of parents. 相似文献
102.
103.
Plasma levels and vascular effects of vasopressin in patients undergoing coronary artery bypass grafting. 总被引:1,自引:0,他引:1
Susana Novella Ana Cristina Martínez Rosa María Pagán Medardo Hernández Albino García-Sacristán Angel González-Pinto José María González-Santos Sara Benedito 《European journal of cardio-thoracic surgery》2007,32(1):69-76
OBJECTIVE: Recent studies have suggested that endogenous vasopressin (AVP) acts as a spasmogen during coronary artery bypass grafting (CABG). Given that AVP could induce vasospasm in the grafted vessel, we assessed the release of this peptide during and after CABG, and explored ways of counteracting its contractile effect on the internal mammary artery (IMA). METHODS: Plasma levels of AVP were determined by radioimmunoassay in 16 patients before, during and after CABG. Using isometric force recording techniques, we also investigated the mechanisms involved in the contractile effect of AVP in ring preparations of IMA specimens taken from 95 patients. RESULTS: Plasma AVP levels peaked after the start of cardiopulmonary bypass (CPB) and correlated well with serum osmolality (Pearson's r=0.9490; P<0.0001; n=16). An inverse correlation was observed between plasma AVP levels recorded at this stage and the maximal contraction induced in vitro by AVP in vascular rings from the same patients (Pearson's r=-0.6968; P<0.01; n=16). No change in the AVP response was produced by endothelium removal, exposure to the NO precursor (3 x 10(-4)M L-arginine), inhibition of nitric oxide (NO) synthase (3 x 10(-5) M L-NAME) or soluble guanylate cyclase (3 x 10(-6) M 1H-[1,2,4]oxadiazol [4,3,-alpha]quinoxalin-1-one (ODQ)), removal of the superoxide anion (100 U/ml superoxide dismutase (SOD) plus 1200 U/ml catalase) or hydroxyl radical (10(-4) M deferoxamine), or specific alpha1 - (10(-6) M prazosin) or endothelin (10(-5) M bosentan) receptor antagonism. In contrast, adenylate cyclase activation (3 x 10(-8) M forskolin) reduced the contractile response to AVP, while prostanoid synthesis (3 x 10(-6) M indomethacin) inhibition and blockade of Ca2+ -activated potassium channels (KCa) (10(-3) M tetraethylammonium (TEA)) enhanced AVP contraction. Age, gender and smoking also modified the AVP response. CONCLUSION: Our findings suggest a role for AVP as a modulator of vascular tone in human IMA. The effect of AVP is dependent on prostanoids and Ca2+ -activated K+ channels, so its dysfunction in pathophysiological cardiovascular processes could mean that AVP, among other factors, produces vasospasm in IMA grafts. 相似文献
104.
Summary We conducted a survey of the presence, prevalence and diversity of gastrointestinal helminths in faecal samples and stomach
contents of three turtle species, &#8212; Erymnochelys madagascariensis (Chelonia: Podocnemididae), Pelomedusa subrufa and Pelusios castanoides (Chelonia: Pelomedusidae), &#8212; from several localities in Madagascar. Four nematode species were detected: Atractis chabaudi, Camallanus chelonius, Falcaustra pelusios, and Spiroxys sp. E. madagascariensis, with all four species, had the greatest helminth diversity. A. chabaudi was the community&#8217;s core species, whereas Spiroxys sp. was a satellite species. Only two species (A. chabaudi and Spiroxys sp.) were found in P. subrufa and only one, Spiroxys sp., in P. castanoides. These are the first helminthological data on E. madagascariensis, one of the most threatened freshwater turtles in the world. 相似文献
105.
106.
107.
Preliminary data suggest that lactitol (beta-galactoside-sorbitol), a new synthetic non-absorbable disaccharide, has beneficial effects on chronic portal systemic encephalopathy. To compare the efficacy of lactitol vs. lactulose in the treatment of acute portal systemic encephalopathy (PSE), 40 cirrhotic patients with an acute episode of PSE were randomly allocated to one of two groups: group A (20 patients) received lactulose (30 ml/6 h) and group B (20 patients) lactitol (12 g/6 h). These doses were adjusted daily to obtain two bowel movements per day. The duration of treatment was 5 days. Age, sex, hepatic and renal function, precipitating factors and level of PSE measured by clinical examination, EEG and number connection test were similar in the two groups. A complete clinical resolution of PSE occurred in 11 patients in each group. In 5 patients of the lactulose group and in 6 of the lactitol group there was a moderate improvement of PSE during the study. Finally, 4 patients in the lactulose group and 3 in the lactitol group did not respond to treatment. No side effects attributable to therapy were observed in either group. These results indicate that lactitol is as effective as lactulose in the management of patients with cirrhosis and acute PSE. 相似文献
108.
109.
110.
Carmen Guillén Ponce María Pilar Garrido López María José Molina Garrido Gema Muñoz Molina Alfredo Carrato 《Clinical & translational oncology》2007,9(1):53-55
Pituitary metastases of solid tumours are infrequent, specially as a first manifestation. When they happen, they are usually
due to breast or lung cancer and are asymptomatic or produce diabetes insipidus. It is very strange that they produce hormonal
deficiency.
We present a case report of a bronchogenic adenocarcinoma in a 65-year-old man which began with panhypopituitarism, diabetes
insipidus and visual alterations. Magnetic resonance imaging revealed a large sellar mass, with clivus infiltration and invading
the right cavernous sinus. The biopsy result was adenocarcinoma metastases from lung cancer. 相似文献