全文获取类型
收费全文 | 3963篇 |
免费 | 169篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 79篇 |
妇产科学 | 137篇 |
基础医学 | 638篇 |
口腔科学 | 71篇 |
临床医学 | 269篇 |
内科学 | 926篇 |
皮肤病学 | 80篇 |
神经病学 | 541篇 |
特种医学 | 199篇 |
外科学 | 407篇 |
综合类 | 36篇 |
一般理论 | 2篇 |
预防医学 | 194篇 |
眼科学 | 36篇 |
药学 | 297篇 |
中国医学 | 3篇 |
肿瘤学 | 184篇 |
出版年
2023年 | 29篇 |
2022年 | 53篇 |
2021年 | 92篇 |
2020年 | 36篇 |
2019年 | 70篇 |
2018年 | 84篇 |
2017年 | 63篇 |
2016年 | 63篇 |
2015年 | 96篇 |
2014年 | 118篇 |
2013年 | 125篇 |
2012年 | 263篇 |
2011年 | 292篇 |
2010年 | 144篇 |
2009年 | 145篇 |
2008年 | 241篇 |
2007年 | 217篇 |
2006年 | 219篇 |
2005年 | 189篇 |
2004年 | 189篇 |
2003年 | 178篇 |
2002年 | 167篇 |
2001年 | 69篇 |
2000年 | 34篇 |
1999年 | 47篇 |
1998年 | 13篇 |
1997年 | 19篇 |
1996年 | 17篇 |
1995年 | 20篇 |
1994年 | 30篇 |
1993年 | 33篇 |
1991年 | 26篇 |
1990年 | 27篇 |
1987年 | 13篇 |
1985年 | 14篇 |
1982年 | 15篇 |
1980年 | 13篇 |
1978年 | 12篇 |
1974年 | 13篇 |
1973年 | 16篇 |
1933年 | 17篇 |
1932年 | 20篇 |
1931年 | 13篇 |
1930年 | 16篇 |
1928年 | 14篇 |
1922年 | 12篇 |
1908年 | 16篇 |
1907年 | 16篇 |
1906年 | 14篇 |
1902年 | 13篇 |
排序方式: 共有4153条查询结果,搜索用时 15 毫秒
1.
María Cabrerizo Gloria Trallero María José Pena Amaia Cilla Gregoria Megias Carmen Mu?oz-Almagro Eva Del Amo Diana Roda Ana Isabel Mensalvas Antonio Moreno-Docón Juan García-Costa Nuria Rabella Manuel Ome?aca María Pilar Romero Sara Sanbonmatsu-Gámez Mercedes Pérez-Ruiz María José Santos-Mu?oz Cristina Calvo And the study group of “Enterovirus parechovirus infections in children under ?years-old Spain” PI- 《European journal of pediatrics》2015,174(11):1511-1516
2.
3.
4.
Ventilation imaging of the lung: Comparison of hyperpolarized helium-3 MR imaging with Xe-133 scintigraphy 总被引:1,自引:0,他引:1
Talissa A. Altes MD Patrice K. Rehm MD Frank Harrell PhD Michael Salerno PhD Thomas M. Daniel MD Eduard E. de Lange MD 《Academic radiology》2004,11(7):729-734
RATIONALE AND OBJECTIVES: To compare hyperpolarized helium-3 (HHe) magnetic resonance imaging (MRI) of the lung with standard Xe-133 lung ventilation scintigraphy. MATERIALS AND METHODS: We performed a retrospective review of 15 subjects who underwent HHe MRI and Xe-133 lung ventilation imaging. Coronal MRI sections were acquired after a single inhalation of HHe gas, and standard posterior planar lung ventilation scintigraphy was performed during continuous breathing of Xe-133 gas. The first breath scintigram of each patient was compared with a composite MR image composed of the sum of the individual MR images and with the individual helium-3 MR images. Ventilation defects on the two imaging modalities were compared for size, conspicuity, and concordance in presence and location. Assessment was done separately for each of four lung quadrants. RESULTS: Comparing the composite HHe MR images with Xe-133 scintigraphy, ventilation defect size, conspicuity and concordance were the same in 67% (40/60), 63% (38/60), and 62% (37/60) quadrants, respectively. Comparing the individual HHe MR image sections with the Xe-133 ventilation scan, there was concordance between the ventilation defects in 27% (16/60) of quadrants. More defects were identified on the individual HHe MR images in 62% (37/60) of quadrants. CONCLUSION: There was good agreement between composite HHe MR image and first breath Xe-133 scintigraphic images, supporting the widely held assumption that HHe MRI likely depicts first breath lung ventilation. 相似文献
5.
The 3-methoxy-4-hydroxyphenylglycol (MHPG) flow, the creatinine flow in 24 h urine and the plasma creatinine level were determined in 42 psychiatric control patients. The creatinine clearance was calculated. The relationship between MHPG flow in 24 h urine and creatinine clearance, creatinine flow, 24 h urinary output, age, sex and weight of the patient were studied by means of single and multiple regression methods. The MHPG flow was significantly correlated with creatinine clearance (r= 0.597), creatinine flow (r = 0.646) and sex of the patient (rpb = 0.434). The variance of the MHPG flow can be explained by the regression with creatinine flow, age and urinary output for at maximum 51.5%. These variables have to be taken into account for the interpretation of data concerning the MHPG flow in subsequent experimental designs. The results of the measurements of the MHPG flow can best be expressed as the residual values obtained after partialling out the predictable component calculated by multiple regression with creatinine flow, age and 24 h urine output. 相似文献
6.
Rene C. Bakker Eduard M. Scholten Johan W. de Fijter Leendert C. Paul 《Transplantation reviews (Orlando, Fla.)》2004,18(1):54-64
Although extensively studied, the pathophysiologic characteristics of chronic cyclosporine (CsA) nephrotoxicity are still far from being completely understood. The recognition of chronic CsA nephrotoxicity in allografted kidneys is hampered by a lack of easily assessable sensitive and specific markers. Long-term results of CsA withdrawal trials and trials that evaluated CsA sparing or withdrawal after the diagnosis of chronic allograft nephropathy (CAN) have shown that chronic CsA nephrotoxicity has a more important role in the etiology of late transplant dysfunction than appreciated before. Various hypotheses have explained the renal structural changes of chronic CsA nephrotoxicity including ischemia, cellular toxicity, and the stimulation of renal fibrosis by growth factors or cytokines. Possible ways to prevent chronic CsA nephrotoxicity include improved therapeutic drug monitoring and CsA withdrawal or avoidance. Patients with aspecific CAN in late biopsy may benefit from withdrawal of CsA or a reduction of its dose. Current knowledge is being discussed. It is concluded that in the near future more strategies are likely to be used to prevent loss of allograft function as a result of drug toxicity. 相似文献
7.
Peter Knesewitsch Sigrid Fritsch Eduard Kleinhans Udalrich Büll 《European journal of nuclear medicine and molecular imaging》1987,12(12):598-601
Results of 203 patients who underwent first pass radionuclide angiography (FP) and quantitative equilibrium radionuclide ventriculography (qERNV) were stored in a data base system and evaluated statistically. Eighty eight of these patients also underwent exercise equilibrium radionuclide ventriculography (E-qERNV). In patients with coronary artery disease (CAD) without previous myocardial infarction (MI), evaluation of global and regional ejection fraction (gEF, rEF) at rest revealed a poor sensitivity of 64%, the specificity was about 71% (qERNV). FP at rest revealed similar values of sensitivity (69%) and specificity (83%). Additional assessment of stress induced changes of gEF, significantly (P<0.05) improved sensitivity of qERNV in CAD patients without a history of previous MI to 84% (specificity 86%). In patients with one previous MI, however, similar values of sensitivity were found (RFP: 87%, R-qERNV: 84%, E-qERNV: 93%). In patients with several MI's, sensitivity was above 90% at rest and during exercise (R-FP: 96%, R-qERNV: 93%, E-qERNV: 100%). 相似文献
8.
Jordi Llorens Cristina Su ol Josep M. Tusell Eduard Rodrí guez-Farr 《Neurotoxicology and teratology》1990,12(6):607-610
The inhibition of [35S]t-butylbicyclophosphorothionate ([35S]TBPS) binding to the GABAA receptor by the insecticide γ-hexachlorocyclohexane, lindane, was studied in several brain regions and using different membrane preparation methods, both in vitro and after dosing the animals with the chemical. In the latter studies, the amount of lindane remaining in the membrane suspensions used for binding assays was determined. In vitro data showed values of IC50 from 150 to 1675 nM, varying in function of the membrane preparation method used. This may account for the discrepancies in IC50 values found in the literature. IC50 values within the range of 150–250 nM were determined using extensively washed membranes from several brain regions, so no evidence arose for brain regional differences in the affinity of lindane for the TBPS binding site. After different schedules of acute treatment with lindane, we found a manifest relationship between the extent of the observable inhibition of [35S]TBPS binding and the lindane amount remaining in the membrane suspensions used for binding assays. This relationship was in good agreement with the in vitro data, so no support for an in vivo acute regulation of the binding site was obtained. 相似文献
9.
The PIM357 satellite DNA family is present in 26 Pimelia taxa (Tenebrionidae, Coleoptera) with endemic congeneric species from the Canary Islands showing higher interrepeat variability
than continental ones. In this paper, we compare the repetitive DNA sequences of a Canarian species that has distinct subfamilies
of repeat units, P. radula ascendens, with another without such subfamilies, P. sparsa sparsa. The chromosomal localization of the repeat units and the comparison of the variability of randomly cloned monomers to the
one estimated by comparing repeat units from dimers and trimers suggest the absence of satellite subfamilies in P. sparsa sparsa. Hence, the repeat units of this species seem to be uniformly and randomly distributed throughout all chromosomes out of
one chromosomal pair. On the contrary, P. radula ascendens shows four divergent subfamilies of repeat units supported by several diagnostic nucleotide substitutions. These subfamilies
seem to form four distinct repeat units: monomer subfamily 1, monomer subfamily 4 and two higher-order units (dimer linking
subfamily 1 and 4, and dimer linking subfamily 2 and 3). Moreover, monomers of subfamily 1 are present in three chromosomal
pairs only. We discuss the effect of different potential factors acting in the concerted evolution and the genomic organization
of stDNA sequences in these taxa.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Hubert A. Shaffer Jr. M.D. Donald A. Eckard Eduard E. de Lange M. R. Ramakrishnan 《Abdominal imaging》1988,13(1):221-223
Hypersensitivity reactions occurring during barium studies of the gastrointestinal tract are rare. A case is presented with radiographically demonstrated angioedema in the stomach and small bowel accompanied by allergic rhinitis, which was apparently an allergic response to the barium sulfate suspension. The reaction was documented twice during separate challenges to the barium suspension performed several months apart. 相似文献