全文获取类型
收费全文 | 102244篇 |
免费 | 5238篇 |
国内免费 | 317篇 |
专业分类
耳鼻咽喉 | 1164篇 |
儿科学 | 2291篇 |
妇产科学 | 2195篇 |
基础医学 | 13616篇 |
口腔科学 | 3832篇 |
临床医学 | 7857篇 |
内科学 | 25378篇 |
皮肤病学 | 2445篇 |
神经病学 | 8748篇 |
特种医学 | 2316篇 |
外科学 | 14005篇 |
综合类 | 509篇 |
一般理论 | 35篇 |
预防医学 | 8686篇 |
眼科学 | 1842篇 |
药学 | 6718篇 |
中国医学 | 391篇 |
肿瘤学 | 5771篇 |
出版年
2024年 | 63篇 |
2023年 | 656篇 |
2022年 | 710篇 |
2021年 | 2056篇 |
2020年 | 1135篇 |
2019年 | 2036篇 |
2018年 | 3174篇 |
2017年 | 2012篇 |
2016年 | 2103篇 |
2015年 | 2770篇 |
2014年 | 3219篇 |
2013年 | 4419篇 |
2012年 | 8716篇 |
2011年 | 8986篇 |
2010年 | 4299篇 |
2009年 | 3331篇 |
2008年 | 7490篇 |
2007年 | 7718篇 |
2006年 | 7563篇 |
2005年 | 7152篇 |
2004年 | 6545篇 |
2003年 | 6039篇 |
2002年 | 5641篇 |
2001年 | 1810篇 |
2000年 | 2276篇 |
1999年 | 1244篇 |
1998年 | 459篇 |
1997年 | 345篇 |
1996年 | 347篇 |
1995年 | 306篇 |
1994年 | 245篇 |
1993年 | 220篇 |
1992年 | 227篇 |
1991年 | 190篇 |
1990年 | 138篇 |
1989年 | 135篇 |
1988年 | 108篇 |
1987年 | 94篇 |
1986年 | 97篇 |
1985年 | 125篇 |
1984年 | 149篇 |
1983年 | 116篇 |
1982年 | 141篇 |
1981年 | 126篇 |
1980年 | 129篇 |
1979年 | 68篇 |
1978年 | 72篇 |
1977年 | 68篇 |
1976年 | 56篇 |
1974年 | 67篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
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
42.
43.
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
44.
Robotic-assisted heller myotomy versus laparoscopic heller myotomy for the treatment of esophageal achalasia: multicenter study 总被引:3,自引:0,他引:3
Santiago Horgan M.D. Carlos Galvani M.D. Maria V. Gorodner M.D. Pablo Omelanczuck M.D. Fernando Elli M.D. Federico Moser M.D. Luis Durand M.D. Miguel Caracoche M.D. Jorge Nefa M.D. Sergio Bustos M.D. Phillip Donahue M.D. Pedro Ferraina M.D. 《Journal of gastrointestinal surgery》2005,9(8):1020-1030
Laparoscopic Heller myotomy (LHM) has become the standard treatment option for achalasia. The incidence of esophageal perforation
reported is about 5%–10%. Robotically assisted Heller myotomy (RAHM) is emerging as a safe alternative to LHM. Data comparing
the two approaches are scant. The aim of this study was to compare RAHM with LHM in terms of efficacy and safety for treatment
of achalasia. A total of 121 patients underwent surgical treatment of achalasia at three institutions. A retrospective review
of prospectively collected perioperative data was performed. Patients were divided into two groups: group A (RAHM), 59 patients,
and group B (LHM), 62 patients. All the operations were completed using minimally invasive techniques. There were 63 women
and 58 men, with a mean age of 45 ±19 years (14–82 years). Fifty-one percent of patients in group A and 95% of patients in
group B reported weight loss. Duration of symptoms was equal for both groups. Dysphagia was the main complaint in both groups
(P = NS). There was no difference in preoperative endoscopic treatment in both groups (44% versus 27%, P = NS). Operative
time was significantly shorter for LHM in the first half of the experience (141 ± 49 versus 122 ± 44 minutes, P < .05). However,
in the last 30 cases there was no difference in operative time between the groups (P = NS). Intraoperative complications (esophageal
perforation) were more frequent in group B (16% versus 0%). The incidence of postoperative heartburn did not differ by group.
There were no deaths. At 18 and 22 months, 92% and 90% of patients had relief of their dysphagia. This study suggests that
RAHM is safer than LHM, because it decreases the incidence of esophageal perforation to 0%, even in patients who had previous
treatment. At short-term follow-up, relief of dysphagia was equally achieved in both groups.
Presented at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–18,
2005 (oral presentation).
This study was supported in part by a grant provided by Intuitive Surgical, Inc. and Ethicon Endo-Surgery, Inc. 相似文献
45.
46.
47.
48.
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
49.
The present study was designed to examine the effects of a >30kDa fraction of medium conditioned for 2 days by adult rat seminiferoustubules on inhibin secretion by cultured tubules, and on spermatogenesisand fertility of male rats. Inhibin secretion was assayed byadding the >30 kDa fraction to 5 cm segments of adult ratseminiferous tubules and measuring inhibin by radioimmunoassayat 2 day intervals. Fertility was assayed by injecting malerats daily for up to 45 days with the >30 kDa fraction andthen mating them with a proestrus female, or by injecting for15 days and mating them with two female rats. The assay usedto evaluate the in-vivo effect of the >30 kDa fraction onthe testis involved an assessment of frequencies of seminiferoustubule stages scored by transillumination on intact tubules.The addition of the >30 kDa fraction to the adult rat seminiferoustubules cultured for 2 days resulted in an inhibition of inhibinsecretion into the medium. This effect was reversed when thefraction was removed and changed with fresh medium and culturedfor a further 4 days. The >30 kDa fraction administered i.p.to adult male rats resulted in a low fertilization rate comparedto control rats (67%) (P < 0.05). The assessment of frequenciesof seminiferous tubule stages scored by transillumination showedan increased frequency of stage VI and decreased frequency ofstages VII and VIII after treatment. The results of the presentstudy provide additional evidence that local regulation of Sertolicell function is mediated by a >30 kDa component or componentssecreted by adult seminiferous tubules which could arrest spermatogenesis. 相似文献
50.