全文获取类型
收费全文 | 4837篇 |
免费 | 262篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 85篇 |
儿科学 | 98篇 |
妇产科学 | 50篇 |
基础医学 | 520篇 |
口腔科学 | 465篇 |
临床医学 | 306篇 |
内科学 | 935篇 |
皮肤病学 | 91篇 |
神经病学 | 312篇 |
特种医学 | 113篇 |
外科学 | 849篇 |
综合类 | 27篇 |
一般理论 | 23篇 |
预防医学 | 636篇 |
眼科学 | 46篇 |
药学 | 325篇 |
中国医学 | 33篇 |
肿瘤学 | 207篇 |
出版年
2024年 | 4篇 |
2023年 | 57篇 |
2022年 | 48篇 |
2021年 | 128篇 |
2020年 | 89篇 |
2019年 | 98篇 |
2018年 | 194篇 |
2017年 | 118篇 |
2016年 | 145篇 |
2015年 | 195篇 |
2014年 | 207篇 |
2013年 | 260篇 |
2012年 | 447篇 |
2011年 | 500篇 |
2010年 | 229篇 |
2009年 | 141篇 |
2008年 | 348篇 |
2007年 | 331篇 |
2006年 | 292篇 |
2005年 | 282篇 |
2004年 | 216篇 |
2003年 | 157篇 |
2002年 | 153篇 |
2001年 | 90篇 |
2000年 | 84篇 |
1999年 | 62篇 |
1998年 | 19篇 |
1997年 | 16篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 16篇 |
1991年 | 15篇 |
1990年 | 20篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1980年 | 6篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1969年 | 6篇 |
1968年 | 3篇 |
排序方式: 共有5121条查询结果,搜索用时 31 毫秒
21.
Determination of hepatitis C virus genotype by Pyrosequencing 总被引:4,自引:0,他引:4
Elahi E Pourmand N Chaung R Rofoogaran A Boisver J Samimi-Rad K Davis RW Ronaghi M 《Journal of virological methods》2003,109(2):171-176
A simple sequencing-based assay is described for genotyping of hepatitis C virus (HCV). RT-PCR was employed to amplify a 237-nucleotide-long fragment from the 5' untranslated region (UTR) of the genome using one biotinylated and one normal primer. Subsequent to capture of the PCR products on streptavidin-coated beads, single-stranded DNA separation, and hybridization of sequencing primer, Pyrosequencing was performed. The genotype of 98 samples out of which 77 samples were from American veterans and 21 samples were from Iran was determined. The samples from the American veterans contained six different subtypes, while five subtypes were found in Iranian samples. For rapid population-specific HCV subtyping, a multiplex assay was developed. This study demonstrates the suitability of this technology for low-cost, high throughput and accurate microbial genotyping. 相似文献
22.
S. M. S. R. Araújo C. C. Silva S. G. Pompolo F. Perfectti J. P. M. Camacho 《Chromosome research》2002,10(7):607-613
Extensive variation in the size of the short (heterochromatic) arm of chromosome 14 was found in the wasp Trypoxylon (Trypargilum) albitarse. Ten different variants were differentiated by size and C-banding pattern. Fluorescent in-situ hybridization (FISH) revealed that ribosomal DNA in this species is clustered in the darkly C-banded parts of the heterochromatic
short arm of chromosome 14. On this basis, we got an indirect estimate of the amount of rDNA from the area of these dark C-bands.
The significant absence in males of the three chromosome variants with lower amounts of rDNA indicates that these three variants
are lethal in this sex, and suggests the existence of a threshold marking the minimum amount of rDNA which is tolerable in
haploidy. This implies about 4% genetic load in the population caused by variation in rDNA amount.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
23.
Uptake of host cell transforming growth factor-beta by Trypanosoma cruzi amastigotes in cardiomyocytes: potential role in parasite cycle completion
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
24.
Ara G. Hovanessian Eliane Meurs Odile Aujean Catherine Vaquero Simon Stefanos Ernesto Falcoff 《Virology》1980,106(1):195-204
Treatment of mouse L929 cells with immune T (type II) interferon resulted in the induction of two double-stranded (ds) RNA-dependent enzymes which have been described previously in viral (type I) interferon-treated cells: pppA(2′p5′A)n synthetase and protein kinase(s). The induction of these enzymes by T interferon was blocked by anti-T but not by antiviral interferon serum. The kinetics of the development of the antiviral state along with a comparison of the levels of pppA(2′p5′A)n synthetase and protein kinase in T and viral interferon-treated cells were investigated. In addition, [35S]methionine-labeled extracts from control, T, and viral inteferon-treated cells were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis. Extracts from cells treated with either type of interferon were found to contain several identical proteins, of estimated molecular weights 60,000, 88,000, and 120,000, which were absent or found at much lower levels in preparations from control cells. The newly synthesized proteins can be partially purified by chromatography on columns of poly(I)·poly(C)-Sepharose, thus providing a convenient method for their further characterization. These results show that treatment of cells with T interferon results in the induction of intracellular events identical to those observed in viral interferon-treated cells. 相似文献
25.
The aim of the present work was to analyze the regenerated muscle types I and II fibers of the soleus and gastrocnemius muscles of mice, 8 months after damage induced by ACL myotoxin (ACLMT). Animals received 5 mg/kg of ACLMT into the subcutaneous lateral region of the right hind limb, near the Achilles tendon; contralateral muscles received saline. Longitudinal and cross sections (10 microm) of frozen muscle tissue were evaluated. Eight months after ACLMT injection, both muscle types I and II fibers of soleus and gastrocnemius muscles still showed centralized nuclei and small regenerated fibers. Compared with the left muscle, the incidence of type I fibers increased in the right muscle (21% +/- 03% versus 12% +/- 06%, P = 0.009), whereas type II fibers decreased (78% +/- 02% versus 88% +/- 06%, P = 0.01). The incidence of type IIC fibers was normal. These results confirm that ACLMT induced muscle type fiber transformation from type II to type I, through type IIC. The area analysis of types I and II fibers of the gastrocnemius revealed that injured right muscles have a higher percentage of small fibers in both types I and II fibers (0-1,500 microm2) than left muscles, which have larger normal type I and II fibers (1,500-3,500 microm2). These results indicate that ACLMT can be used as an excellent model to study the rearrangement of motor units and the transformation of muscle fiber types during regeneration. 相似文献
26.
We investigated the relationship between Arc (activity-regulated cytoskeleton-associated protein) and Ca(2+)/calmodulin-dependent protein kinase II (CaM kinase II). Arc and CaM kinase II were concentrated in the postsynaptic density. These proteins were accumulated after electroconvulsive treatment. Arc increased about 2.5-fold within 30 min and was maintained at this level for 8h after the stimulation. CaM kinase II also increased within 30 min and remained at this level for at least 24h. The interaction of Arc with CaM kinase II was demonstrated using GST-Arc fusion protein, and confirmed in neuroblastoma cells by immunoprecipitation. We examined the function of Arc by introducing Arc cDNA into neuroblastoma cells expressing CaM kinase II. The cells expressing both Arc and CaM kinase II had longer neurites than those expressing CaM kinase II alone. Arc itself did not promote neurite outgrowth. The growth of neurites by Arc was completely blocked by treatment with KN62, an inhibitor of CaM kinases. These results indicated that Arc potentiated the action of CaM kinase II for neurite extension. 相似文献
27.
de Sousa SO Schwarzschild M de Araújo NS de Araújo VC 《Journal of clinical pathology》2000,53(2):153-156
Basal cell adenocarcinoma is a rare salivary gland tumour, especially in minor glands. The clinical, histological, and immunohistochemical features of a case involving the palate are described. Formalin fixed, paraffin embedded sections of the tumour were examined in haematoxylin and eosin (H&E) sections and also using immunostaining for cytokeratins 7, 8, 13, 14, 18, 19, vimentin, muscle specific actin (HHF35), and laminin. H&E sections showed that the tumour was composed mainly of basaloid cells and a striking feature was the presence of squamous metaplasia. Neural invasion was also conspicuous. Immunohistochemical reactions indicated that cytokeratin 14 was expressed by all tumour cells and vimentin by all cells except those in the areas of squamous metaplasia. The remaining cytokeratins and actin were present in some of the tumour cells, while laminin showed discreet positivity around cell arrangements. The foci of squamous metaplasia and the immunohistochemical findings are helpful in distinguishing basal cell adenocarcinoma from other salivary gland tumours which show basaloid cells. 相似文献
28.
Donangelo I Marcos HP Araújo PB Marcondes J Filho PN Gadelha M Chimelli L 《Endocrine pathology》2005,16(1):53-62
The retinoblastoma gene (RB1) is a tumor-suppressor gene in chromosomal region 13q14.2. Its role in the pathogenesis of pituitary tumors has not been
fully clarified. Some studies have shown that losses in this chromosomal region are related to aggressive tumor behavior,
although the retinoblastoma protein (pRB) is still expressed. Conversely, lack of expression of pRB was observed in one fourth
of GH-secreting pituitary adenomas (GH-tumors). In order to further study the expression of pRB in GH-tumors, we evaluated
this protein in 49 tumors from patients with acromegaly (20 noninvasive, 25 invasive, and 4 with no information) and 8 normal
pituitaries using immunohistochemistry (IHC). Nuclear staining for pRB ranged from 0 to 90% (median 40%) in the tumors and
from 40 to 80% (median 58%) in normal pituitaries. In 10 tumors (20% of total) the adenomatous cells were negative (5 cases)
or had very low labeling (5 cases) for pRB. Sixty three percent (31/49) of the tumors showed staining in 10–80% of the cells
and in 16% (8/49) of the cases >80% of the adenomatous cells were positive for pRB. The expression of pRB was not different
in invasive and noninvasive tumors. In conclusion, pRB is underexpressed in a subgroup of GH-tumors, and this may represent
an early event in the pathogenesis of this tumor subtype. 相似文献
29.
R. S. C. Araújo E. M. B. Guimarães M. F. C. Alves E. Sakurai L. T. Domingos F. C. R. Fioravante A. C. S. Machado 《European journal of clinical microbiology & infectious diseases》2006,25(6):397-400
In order to determine the prevalence and risk factors for Chlamydia trachomatis infection in adolescent females and young women in central Brazil, 296 subjects attending two public health services were evaluated. The overall prevalence of C. trachomatis infection, as determined using polymerase chain reaction, was 19.6% (95% confidence interval [CI], 15.3–24.7). In multivariate analysis, young age (odds ratio [OR]adjusted 2.32, 95%CI 1.1–4.8, p<0.05) and having 2–3 (ORadjusted 3.41, 95%CI 1.6–6.3, p<0.05) or ≥4 sexual partners in life (ORadjusted 3.10, 95%CI 1.1–6.3, p<0.05) were factors significantly associated with chlamydial infection. In conclusion, the prevalence of C. trachomatis infection was high in the studied population and risk factors were related to age and sexual behavior. 相似文献
30.
del Ara RM González-Polo RA Caro A del Amo E Palomo L Hernández E Soler G Fuentes JM 《Clinical and experimental medicine》2002,2(1):53-57
Arginase activity was measured in serum and biopsy from healthy individuals and colorectal cancer patients. Arginase activity
in tumor samples (87±7.7 U/g tissue) was significantly higher than in controls (40.7±3.3 U/g tissue). However, serum arginase
activity did not show any significant change in both groups. Finally, the micromethod used to quantify arginase activity in
this study is superior to other methods because it has increased sensitivity, requires less sample, and is less time-consuming.
Arginase differences are significant, according to the t-test (P<0.05).
Received: 14 September 2001 / Accepted: 6 February 2002 相似文献