全文获取类型
收费全文 | 2757篇 |
免费 | 207篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 36篇 |
儿科学 | 80篇 |
妇产科学 | 54篇 |
基础医学 | 352篇 |
口腔科学 | 30篇 |
临床医学 | 349篇 |
内科学 | 446篇 |
皮肤病学 | 32篇 |
神经病学 | 179篇 |
特种医学 | 54篇 |
外科学 | 302篇 |
综合类 | 76篇 |
预防医学 | 363篇 |
眼科学 | 21篇 |
药学 | 173篇 |
中国医学 | 4篇 |
肿瘤学 | 416篇 |
出版年
2023年 | 27篇 |
2022年 | 43篇 |
2021年 | 84篇 |
2020年 | 53篇 |
2019年 | 66篇 |
2018年 | 70篇 |
2017年 | 72篇 |
2016年 | 59篇 |
2015年 | 82篇 |
2014年 | 97篇 |
2013年 | 177篇 |
2012年 | 212篇 |
2011年 | 199篇 |
2010年 | 111篇 |
2009年 | 111篇 |
2008年 | 173篇 |
2007年 | 159篇 |
2006年 | 155篇 |
2005年 | 158篇 |
2004年 | 156篇 |
2003年 | 137篇 |
2002年 | 136篇 |
2001年 | 38篇 |
2000年 | 35篇 |
1999年 | 35篇 |
1998年 | 18篇 |
1997年 | 24篇 |
1996年 | 24篇 |
1995年 | 19篇 |
1994年 | 20篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 18篇 |
1990年 | 12篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1972年 | 6篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1969年 | 5篇 |
排序方式: 共有2967条查询结果,搜索用时 15 毫秒
81.
82.
The influence of school smoking policies on student tobacco use 总被引:1,自引:0,他引:1
Barnett TA Gauvin L Lambert M O'Loughlin J Paradis G McGrath JJ 《Archives of pediatrics & adolescent medicine》2007,161(9):842-848
OBJECTIVE: To investigate the association between smoking behavior among secondary school students and school smoking policies. DESIGN: Cross-sectional provincially representative study. SETTING: Quebec secondary schools. PARTICIPANTS: Complete data were available for 763 of 1058 students aged 13 years in 50 schools and for 768 of 1160 students aged 16 years in 57 schools. School principals provided data on school smoking policies. Main Exposure School smoking policies. Outcome Measure Student tobacco use. RESULTS: Of students aged 13 years, 3.8% of boys and 7.1% of girls smoked daily; 21.0% of boys and 25.2% of girls aged 16 years smoked daily. Of schools, 28.0% permitted staff to smoke indoors, 84.1% permitted staff to smoke outdoors on school grounds, and 83.2% permitted students to smoke outdoors on school grounds. Daily smoking was not associated with policies targeting student smoking or those targeting indoor smoking by staff. In multilevel analyses, girls aged 13 years were almost 5 times more likely to be daily smokers if they attended schools at which staff were permitted to smoke outdoors. CONCLUSIONS: Younger girls may be more susceptible to social influences at school related to tobacco use. School policies banning smoking by teachers and other school personnel within and outside the school should be an important component of comprehensive adolescent smoking prevention programs. 相似文献
83.
Dominika Dziedzicka Christina Markouli Lise Barbé Claudia Spits Karen Sermon Mieke Geens 《Stem cell reviews》2016,12(6):721-730
When aiming for homogenous embryoid body (EB) differentiation, the use of equal-sized EBs is required to avoid a size-induced differentiation bias. In this study we developed an efficient and standardized EB formation protocol for human pluripotent stem cells (hPSC) cultured in a laminin-521-based xeno-free system. As the cell proliferation rate of the cells growing on laminin-521 strongly affected the efficiency of aggregate formation, we found that recently passaged cells, as well as the addition of ROCK inhibitor, were essential for reproducible EB formation from hPSC single-cell suspensions. EBs could be obtained in a variety of differentiation media, in 96-well round-bottom plates and in hanging drops. Gene expression studies on differentially sized EBs from three individual human embryonic stem cell lines demonstrated that the medium used for differentiation influenced the differentiation outcome to a much greater extent than the number of cells used for the initial EB formation. Our findings give a new insight into factors that influence the EB formation and differentiation process. This optimized method allows us to easily manipulate EB formation and provide an excellent starting point for downstream EB-based differentiation protocols. 相似文献
84.
Monitoring of basophil activation using CD63 and CCR3 in allergy to muscle relaxant drugs 总被引:12,自引:0,他引:12
Monneret G Benoit Y Debard AL Gutowski MC Topenot I Bienvenu J 《Clinical immunology (Orlando, Fla.)》2002,102(2):192-199
Allergic or pseudoallergic reactions that occur during anesthesia have been increasing for the last few years. To date, the diagnosis of allergy to muscle relaxants remains difficult. In this respect, we developed a flow cytometric method for the study of drug-induced basophil degranulation using CD63 and CCR3. Fifty patients who developed clinical features evocative of allergic reactions immediately after induction of anesthesia were included and classified into two groups. Group 1 (n = 39) comprised true allergic patients, who developed typical signs of shock associated to positive skin testing. Group 2 (n = 11) consisted of patients whose clinical history was not typical and skin testing was negative or nonconclusive. Seventeen control subjects were also studied in this report. We compared data from flow cytometry to skin tests, specific IgE, and histamine release results. Flow cytometry showed a sensitivity of 54%, while that of specific IgE was similar, at 62%. Interestingly, when considering the sensitivity of IgE + CD63 for diagnosis, we reached a sensitivity value of 80%. Of 15 negative results for specific IgE, we found 7 positive CD63 tests, while histamine release gave positive results in only 2 cases. Furthermore, the CD63 protocol showed good specificity (100%). We conclude that our flow cytometry protocol is a promising tool in allergy diagnosis since it is specific and complementary to specific IgE detection. 相似文献
85.
S. Lise S. Clasper H. Stewart E. S. Akha G. Quaghebeur S. J. L. Knight D. A. Keays U. Kini 《Clinical genetics》2016,90(3):258-262
Kabuki syndrome is a heterogeneous condition characterized by distinctive facial features, intellectual disability, growth retardation, skeletal abnormalities and a range of organ malformations. Although at least two major causative genes have been identified, these do not explain all cases. Here we describe a patient with a complex Kabuki‐like syndrome that included nodular heterotopia, in whom testing for several single‐gene disorders had proved negative. Exome sequencing uncovered a de novo c.931_932insTT variant in HNRNPK (heterogeneous nuclear ribonucleoprotein K). Although this variant was identified in March 2012, its clinical relevance could only be confirmed following the August 2015 publication of two cases with HNRNPK mutations and an overlapping phenotype that included intellectual disability, distinctive facial dysmorphism and skeletal/connective tissue abnormalities. Whilst we had attempted (unsuccessfully) to identify additional cases through existing collaborators, the two published cases were ‘matched’ using GeneMatcher, a web‐based tool for connecting researchers and clinicians working on identical genes. Our report therefore exemplifies the importance of such online tools in clinical genetics research and the benefits of periodically reviewing cases with variants of unproven significance. Our study also suggests that loss of function variants in HNRNPK should be considered as a molecular basis for patients with Kabuki‐like syndrome. 相似文献
86.
Kveberg L Bryceson Y Inngjerdingen M Rolstad B Maghazachi AA 《European journal of immunology》2002,32(7):1856-1864
We have examined the effect of sphingolipids on the chemotaxis of human natural killer (NK) cells. Messenger RNA for Edg-1, Edg-6 and Edg-8 but not Edg-3, are expressed in these cells. Sphingosine 1 phosphate (SPP), dihydro SPP (DHSPP) or the CC chemokine RANTES (CCL5), but not sphingosine induces the chemotaxis of these cells. Pertussis toxin inhibits the chemotaxis induced by these ligands. Permeabilization of NK cells with streptolysin O (SLO) and introduction of blocking antibodies to the heterotrimeric G proteins, showed that Galpha(i2), Galpha(s), Galpha(q/11) or Galpha(13) mediate the chemotaxis of SPP, whereas Galpha(i2), Galpha(o) or Galpha(q/11) mediate the chemotaxis of DHSPP. Galpha(i2), Galpha(o), Galpha(s), Galpha(q/11), Galpha(z) or Galpha(12 )mediates RANTES-induced NK cell chemotaxis. Further analysis showed that phosphoinositide 3 kinase (PI3K) inhibitors wortmannin and LY294002 inhibit NK cell chemotaxis induced by SPP, DHSPP or RANTES. Blocking antibody to PI3Kgamma inhibits the chemotaxis induced by the three ligands, whereas anti-PI3Kbeta was without effect. In contrast, SPP and DHSPP recruit PI3Kbeta isozyme into NK cell membranes, suggesting that although this isoform is not involved in chemotaxis, it is activated by these phospholipids. 相似文献
87.
Sarih M M'Ghirbi Y Bouattour A Gern L Baranton G Postic D 《Journal of clinical microbiology》2005,43(3):1127-1132
A broad-range 16S rRNA gene PCR assay followed by partial sequencing of the 16S rRNA gene was used for the detection of members of the family Anaplasmataceae in ticks in North Africa. A total of 418 questing Ixodes ricinus ticks collected in Tunisia and Morocco, as well as 188 Rhipicephalus ticks from dogs and 52 Hyalomma ticks from bovines in Tunisia, were included in this study. Of 324 adult I. ricinus ticks, 16.3% were positive for Ehrlichia spp., whereas only 3.4 and 2.8% of nymphs and larvae, respectively, were positive. A large heterogeneity was observed in the nucleotide sequences. Partial sequences identical to that of the agent of human granulocytic ehrlichiosis (HGE) were detected in I. ricinus and Hyalomma detritum, whereas partial sequences identical to that of Anaplasma platys were detected in Rhipicephalus sanguineus. However, variants of Anaplasma, provisionally designated Anaplasma-like, were predominant in the I. ricinus tick population in Maghreb. Otherwise, two variants of the genus Ehrlichia were detected in I. ricinus and H. detritum. Surprisingly, a variant of Wolbachia pipientis was evidenced from I. ricinus in Morocco. These results emphasized the potential risk of tick bites for human and animal populations in North Africa. 相似文献
88.
Chassaing N Siani V Carles D Delezoide AL Alberti EM Battin J Chateil JF Gilbert-Dussardier B Coupry I Arveiler B Saura R Lacombe D 《American journal of medical genetics. Part A》2005,(4):307-312
We describe a family with an X-linked dominant chondrodysplasia. Four males and six females were affected through four generations. Identification of skeletal abnormalities and hydrocephaly during the pregnancy of three male fetuses led to termination of the pregnancies. A fourth affected male died at 6 days of life. The four patients had chondrodysplasia, hydrocephaly, and facial features with microphthalmia. Radiographs showed severe platyspondyly and various bone abnormalities including a distinctive metaphyseal cupping of the metacarpals, metatarsals, and phalanges. The affected females were less affected and showed small stature, sometimes associated with body asymmetry and mild mental retardation. This condition appears to be a previously unrecognized X-linked dominant chondrodysplasia. 相似文献
89.
Høgdall EV Christensen L Kjaer SK Blaakaer J Jarle Christensen I Gayther S Jacobs IJ Høgdall CK 《Pathology》2008,40(5):487-492
AIMS: To determine the variation in expression of carcinoembryonic antigen (CEA) in 760 epithelial ovarian tumours from Denmark, and to correlate expression with clinicopathological parameters and prognosis for the disease. METHODS: Using tissue arrays (TA), we analysed CEA expression in tissues from 189 women diagnosed with low malignant potential ovarian tumours (LMP, borderline ovarian tumours) and 571 women diagnosed with ovarian cancer (OC). RESULTS: Using 30% as the cut-off level for CEA over-expression, 18% of LMPs and 4% of OCs were positive. A higher proportion of mucinous tumours were positive compared with other histological subtypes (p<0.00001). A univariate survival analysis suggested a shorter disease specific survival for patients with 30% or higher CEA expression in the tumour tissue (p = 0.004). In a Cox survival analysis, which included 569 OC cases subgrouped by stage (I to IV), the highest CEA expression compared with no expression was found to be a prognostic factor (level 3 versus negative: HR = 2.12, 95%CI 1.11-4.05). FIGO stage, residual tumour after primary surgery, age at diagnosis, other histological types versus serous adenocarcinoma and low versus high histological grade tumours were also prognostic factors. CONCLUSION: These data suggest that CEA expression is an independent prognostic factor for mucinous OC in Danish patients. 相似文献
90.