全文获取类型
收费全文 | 19851篇 |
免费 | 1115篇 |
国内免费 | 56篇 |
专业分类
耳鼻咽喉 | 321篇 |
儿科学 | 435篇 |
妇产科学 | 459篇 |
基础医学 | 2818篇 |
口腔科学 | 1898篇 |
临床医学 | 1200篇 |
内科学 | 3996篇 |
皮肤病学 | 407篇 |
神经病学 | 1846篇 |
特种医学 | 582篇 |
外科学 | 2188篇 |
综合类 | 39篇 |
一般理论 | 7篇 |
预防医学 | 1974篇 |
眼科学 | 450篇 |
药学 | 1651篇 |
中国医学 | 172篇 |
肿瘤学 | 579篇 |
出版年
2023年 | 190篇 |
2022年 | 251篇 |
2021年 | 574篇 |
2020年 | 344篇 |
2019年 | 537篇 |
2018年 | 894篇 |
2017年 | 627篇 |
2016年 | 600篇 |
2015年 | 598篇 |
2014年 | 693篇 |
2013年 | 1024篇 |
2012年 | 1764篇 |
2011年 | 2003篇 |
2010年 | 925篇 |
2009年 | 580篇 |
2008年 | 1396篇 |
2007年 | 1377篇 |
2006年 | 1169篇 |
2005年 | 1114篇 |
2004年 | 1095篇 |
2003年 | 849篇 |
2002年 | 624篇 |
2001年 | 293篇 |
2000年 | 335篇 |
1999年 | 222篇 |
1998年 | 80篇 |
1997年 | 47篇 |
1996年 | 43篇 |
1995年 | 34篇 |
1994年 | 33篇 |
1993年 | 30篇 |
1992年 | 46篇 |
1991年 | 43篇 |
1990年 | 28篇 |
1989年 | 30篇 |
1988年 | 37篇 |
1987年 | 31篇 |
1986年 | 34篇 |
1985年 | 56篇 |
1984年 | 29篇 |
1983年 | 16篇 |
1982年 | 17篇 |
1981年 | 24篇 |
1980年 | 25篇 |
1978年 | 21篇 |
1977年 | 16篇 |
1974年 | 16篇 |
1971年 | 21篇 |
1970年 | 23篇 |
1969年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
J. Serra G. Capella J. Esquius R. Montañes X. Rius 《International journal of colorectal disease》1992,7(1):21-25
Colorectal surgery is still associated with a significant morbidity and mortality rate, mostly related to suture failure. We have carried out a randomized experimental study in dogs on colonic anastomoses exposed to a number of anastomotic risk situations. A total of 42 dogs was used. They were divided into three study groups (control, occlusion and diverticulitis), with and without an endoluminal tube. The aim was to assess the efficacy of the endoluminal prosthesis using clinical and radiological assessment of anastomotic healing. Pre- and post-anastomotic intraluminal pressures were also measured to determine whether these might be a factor in suture failure. There were significant differences in suture failure in animals in which the endoluminal tube was used. Mean duration of placement was 10.5 days. In the colon healing study, no significant differences were found between the groups in the pathological examination or in the assay of hydroxyproline content. The presence of the endoluminal tube may increase the maximum pressure applied on the colon wall. No significant differences were found in the intracolonic pressure differentials between the different groups or after the inclusion of the endoluminal prosthesis. The results obtained establish the efficacy of the endoluminal prosthesis in protecting the colonic anastomosis, and could be a valuable technique in colonic anastomoses with a high risk of suture dehiscence. 相似文献
52.
Desmond FS Cormack RMN RGN MPhil DipEd PhD DipN Honorary Reader in Health Nursing William Reynolds RMN RNT RGN MPhil Senior Tutor 《Journal of advanced nursing》1992,17(12):1472-1478
Arguably, nursing, like all health care disciplines, is an applied science. Essentially, this refers to the application of theory in order to understand and respond to the health problems of clients. These theories may be drawn (borrowed) from any applied science, or generated inductively from clinical nursing practice. Alternatively, nurses may attempt to apply deductive theory (global theoretical frameworks) known as nursing models. In this paper, all theoretical approaches, irrespective of origin, are referred to as models used by nurses. Thirteen criteria by which clinicians, and others, can evaluate the clinical and practical utility of models used by nurses which are expressed in the form of questions are identified and discussed. The criteria are an extension, both in detail and in number, of those developed by Reynolds and Cormack and subsequently applied by those writers to the Johnson Behavioural System Model of Nursing. The value, or otherwise, of individual models, or of models in general, will not be discussed in this paper. However, the authors propose that if the evaluation criteria described here are applied to existing models, serious deficits will be identified in relation to their clinical and practical utility. 相似文献
53.
54.
Jose Carlos de Fraga João Pippi Salle Mauro Boher Carlos R. Antunes 《Pediatric surgery international》1995,10(5-6):376-378
Laryngotracheoesophageal cleft is an uncommon disease that is difficult to diagnose and treat. Repair of the cleft depends on length and localization of the defect as well as the associated anomalies. A successful repair of a type II cleft is reported in this paper. An anterior split of the larynx and trachea was used and provided excellent exposure and safe repair without injury to the neurovascular structures. This is the best approach and should be used to correct all type II defects. 相似文献
55.
Bongertz Costa Guimarães Grinsztejn The Hec/fiocruz Aids Clinical Research Group João Filho Galvão-Castro & Morgado 《Scandinavian journal of immunology》1998,47(6):603-608
Susceptibility to autologous and heterologous neutralization of primary human immunodeficiency virus (HIV)-1 isolates belonging to subtype B, to the B'-variant of subtype B or to subtype F from infected individuals residing in Rio de Janeiro was assayed. A lower infectivity of the B'- and F isolates when compared to the classical B-subtype HIV-1 isolates was observed. Comparisons of neutralization susceptibilities were carried out for 19 B-subtype, 11 B'-variant and two F-subtype HIV-1 isolates with plasma from autologous and heterologous samples. Frequency of autologous neutralization was slightly lower for B-subtype isolates in comparison to B'-variant isolates. Heterologous intra-subtype neutralization was significantly lower for B-subtype than for the B'-variant or the F-subtype isolates. While B-subtype isolates were neutralized by most anti-F-subtype plasma, F-subtype isolates, although most susceptible to F-subtype antibodies, were highly susceptible to neutralization by anti-B-subtype antibodies. Cross-neutralization for B'-variant and B-subtype isolates was not as extensive as observed for B- and F-subtype isolates. However, the results presented indicate a quite extensive cross-neutralization between Brazilian HIV-1 isolates. 相似文献
56.
J. Gonçalves F. Carvalho S. Guimarães 《Naunyn-Schmiedeberg's archives of pharmacology》1989,339(3):288-292
Summary The present study was undertaken to compare the presynaptic interaction of neuronal noradrenaline uptake inhibitors with imidazoline and phenylethylamine 2adrenoceptor agonists under two different conditions: at low and high noradrenaline concentrations in the biophase.Isolated mouse vasa deferentia were stimulated with trains of 7 pulses given at 0.2 Hz and the inhibition by the 2-adrenoceptor agonists clonidine, -methylnoradrenaline, and UK-14,304 of twitch responses was measured in the absence and in the presence of either cocaine (12 mol/l) or desipramine (40 nmol/l). The effects were determined for the first (equivalent to single pulse stimulation) and the last stimulus of each train. Both uptake inhibitors antagonized the presynaptic inhibitory effects of imidazolines (clonidine and UK-14,304) on the last twitch; the effects on the first twitch remained unchanged. In contrast, the uptake inhibitors potentiated the inhibitory effect of the phenylethylamine (-methylnoradrenaline) on both the first and the last twitches.These results support the view that the concentration of noradrenaline in the biophase plays a decisive role in the inhibition by a2-adrenoceptor agonists of the electrically evoked release of noradrenaline. Agonists that are not substrates of neuronal uptake (i.e., clonidine, UK-14,304) become less effective when noradrenaline is present in the biophase while substrates of neuronal uptake (i. e., -methylnoradrenaline) do not. The results argue against the hypothesis that uptake inhibitors interact directly with presynaptic 2-adrenoceptors or act at some link between uptake and receptor sites.
Send offprint requests to S. Guimarães at the above address 相似文献
57.
Sandra Martins Ana I Seixas Paula Magalh?es Paula Coutinho Jorge Sequeiros Isabel Silveira 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2005,(1):109-114
Spinocerebellar ataxia type 8 (SCA8) is an autosomal dominant late-onset neurodegenerative disorder, belonging to the group of diseases caused by trinucleotide repeat expansions. SCA8 remains one of the most intriguing SCAs, regarding the reduced disease penetrance, and the high instability and poorly understood functional meaning of the (CTA)(n)(CTG)(n) expansion. We performed haplotype and sequencing analysis in a large region, encompassing the repeat, in four SCA8 and 20 control Portuguese families. The results from the haplotype study including the combined repeat and six SNP markers showed two different haplotypes, AG-Exp-GTTG and AG-Exp-CTTG, in the SCA8 families. Among the control population, these were also the most frequent, in a total of five haplotypes found unequally distributed throughout repeat sizes. From cloning fragments of control, unstable normal and expanded chromosomes, eleven different base substitutions were identified in exon A of the SCA8 gene. In some instances, somatic variability in repeat size or base composition was found for a same chromosome, regardless of its normal or expanded nature. In conclusion, our results in Portuguese families with ataxia show that SCA8 expansions arose in common backgrounds; in addition, this region seems to be unstable beyond the repeat. 相似文献
58.
Breast cancer micrometastases: Different interactions of carcinoma cells with normal and cancer patients' bone marrow stromata 总被引:6,自引:1,他引:6
Nicola MH Bizon R Machado JJ Sollero T Rodarte RS Nobre JS Magalhães MM Takiya CM Borojevic R 《Clinical & experimental metastasis》2003,20(5):471-479
The apparently dormant breast cancer micrometastases in haemopoietic marrow are correlated with distant metastatic carcinoma
dissemination. We studied in vitro interactions of carcinoma cells with adjacent stromata, using connective tissue cell cultures from breast and bone marrow
samples of normal donors, comparing them to the pericancerous breast tissue and bone marrows of 12 selected patients with
invasive breast carcinomas. Cancer cells were detected by immunocytochemistry and RT-PCR in all the bone marrows and in most
blood samples of the studied patients. We monitored the growth and interaction of carcinoma MCF-7 cells with the stromata.
The normal breast stroma sustained typical massive cancer growth. The pericancerous breast stroma induced the invasive mesenchymal
pattern of growth. Normal bone marrow stroma induced the same conversion and was highly adhesive, retaining the cells in the
stroma, but carcinoma patients' bone marrow stromata underwent low adhesive interactions with cancer cells, releasing them
potentially into the circulation. The semi-quantitative RT-PCR indicated an enhanced expression of the hepatocyte growth factor
and its receptor c-met in breast and bone marrow stromata of cancer patients. The input of cancer cells into the normal bone marrow may induce modifications
of the local microenvironment, favourable for growth and release of carcinoma cells into the systemic circulation, which correlate
with the poor prognosis of patients with bone marrow micrometastases.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
59.
Alves C Silva F Gusmão L Seruca R Soares P Reis RM Amorim A 《European journal of human genetics : EJHG》2000,8(7):540-544
The promoter region of the human GSTP1 gene contains a polymorphic short tandem repeat (STR) locus consisting of pentanucleotide repeat units (ATAAA). In this work we report the existence of a total of 26 alleles in a Caucasian population. While differences in size (ranging from one to five base pairs) were responsible for the major variation, in five size-defined classes, two alternative sequences were found. Automatic fragment sizing and sequencing analysis revealed that this polymorphism is of a highly complex nature in contrast with previous reports. A genetic population study was carried out on a random sample from Portugal showing no deviation from Hardy-Weinberg equilibrium. Somatic instability studies were also performed on gastric and thyroid tumours using this STR: no instability was detected in thyroid tumour tissues when compared with their normal counterpart but in gastric tumour tissues microsatellite instability (MSI) was detected in 9.6% of the cases and loss of heterozygosity (LOH) also in 9.6% of the cases studied. The results obtained with GSTP1 in gastric cancer were compared with previously reported data on MSI using BAT-26 and several dinucleotide repeat markers. 相似文献
60.
de Andrade AL Pimenta FC Laval CA de Andrade JG Guerra ML Brandileone MC 《Journal of clinical microbiology》2004,42(5):2345-2346
We present a case of invasive pneumococcal infection in a healthy 10-month-old infant from whom Streptococcus pneumoniae serotype 23F was isolated from the blood and serotype 23B was isolated from the cerebrospinal fluid. Both serotypes were penicillin nonsusceptible. Pulsed-field gel electrophoresis analysis demonstrated that the two serotypes had distinct DNA patterns, indicating that infection did not occur as a result of capsular transformation but as a result of a mixed infection with two distinct pneumococcal serotypes. 相似文献