全文获取类型
收费全文 | 6172篇 |
免费 | 306篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 408篇 |
妇产科学 | 73篇 |
基础医学 | 579篇 |
口腔科学 | 101篇 |
临床医学 | 416篇 |
内科学 | 1388篇 |
皮肤病学 | 178篇 |
神经病学 | 357篇 |
特种医学 | 194篇 |
外科学 | 1047篇 |
综合类 | 130篇 |
一般理论 | 3篇 |
预防医学 | 269篇 |
眼科学 | 299篇 |
药学 | 457篇 |
中国医学 | 18篇 |
肿瘤学 | 478篇 |
出版年
2023年 | 47篇 |
2022年 | 64篇 |
2021年 | 226篇 |
2020年 | 106篇 |
2019年 | 139篇 |
2018年 | 182篇 |
2017年 | 127篇 |
2016年 | 134篇 |
2015年 | 160篇 |
2014年 | 232篇 |
2013年 | 275篇 |
2012年 | 440篇 |
2011年 | 457篇 |
2010年 | 273篇 |
2009年 | 188篇 |
2008年 | 335篇 |
2007年 | 348篇 |
2006年 | 342篇 |
2005年 | 329篇 |
2004年 | 281篇 |
2003年 | 232篇 |
2002年 | 218篇 |
2001年 | 96篇 |
2000年 | 70篇 |
1999年 | 81篇 |
1998年 | 51篇 |
1997年 | 43篇 |
1996年 | 41篇 |
1995年 | 39篇 |
1994年 | 25篇 |
1993年 | 27篇 |
1992年 | 87篇 |
1991年 | 63篇 |
1990年 | 49篇 |
1989年 | 62篇 |
1988年 | 49篇 |
1987年 | 43篇 |
1986年 | 52篇 |
1985年 | 41篇 |
1984年 | 34篇 |
1983年 | 21篇 |
1981年 | 21篇 |
1979年 | 33篇 |
1977年 | 20篇 |
1976年 | 33篇 |
1975年 | 23篇 |
1972年 | 21篇 |
1971年 | 23篇 |
1970年 | 28篇 |
1969年 | 27篇 |
排序方式: 共有6494条查询结果,搜索用时 852 毫秒
31.
32.
R Dhawan U C Chaturvedi M Khanna A Mathur B L Tekwani V C Pandey R N Rai 《International journal of experimental pathology》1991,72(1):31-39
The role of calcium ions (Ca2+) in the cytotoxic activity of the dengue type 2 virus (DV)-induced macrophage (M phi) cytotoxin (CF2) was investigated in the present study. The findings show that CF2 prepared in Ca(2+)-free medium had no cytotoxic activity on normal mouse spleen cells suspended in Ca(2+)-free medium but killed the cells suspended in the medium with Ca2+. Substitution with calcium chloride restored the cytotoxic activity of CF2 the optimal dose being 10(-4) M concentration. CF2 induced an influx of Ca2+, as assayed by uptake of radiolabelled calcium chloride (45Ca), in the susceptible target cells, viz. M phi and T lymphocytes. The cytotoxic activity of CF2 as well as the CF2-induced influx of 45Ca was inhibited by treatment of the target cell with the calcium channel blocking drugs verapamil and nifedipine. Thus, the presence of Ca2+ is obligatory for the cytotoxic activity of CF2 and cell death is associated with increased intracellular Ca2+. 相似文献
33.
Sharma R Mondal A Sahoo M Kakar A Shankar LR Khanna CM Chopra MK Soni NL 《The Journal of the Association of Physicians of India》1999,47(5):488-491
One hundred and forty eight subjects with euthyroid solitary thyroid nodules (STN) were taken up for radionuclide perfusion study. They were found to have a cold STN on 99mTc thyroid static scan. All had fine needle aspiration cytology (FNAC), and except for subjects with chronic lymphocytic thyroiditis, were subjected to surgery for tissue diagnosis by histopathology. The diagnostic findings in these patients of solitary thyroid nodules were correlated with the histopathology. Radionuclide perfusion study is considered useful to differentiate benign from malignant cold thyroid solitary nodules with high degree of sensitivity (95%) and specificity (87.9%). 相似文献
34.
The effect of mammalian insulin was studied in a freshwater fish, Clarias batrachus, at both high and low ambient temperatures. The hormone produced a significant but delayed, yet recoverable, lowering of blood glucose, a concurrent decrease in liver glycogen, and an increase in the glycogen content of muscles. The decrease in brain glycogen occurred during advanced hypoglycemia. Hypoglycemic seizures developed intermittently in most of the fishes whose plasma glucose and brain glycogen levels had been considerably depleted. Necrobiotic changes in the pancreatic islets, including degranulation and atrophy, and necrosis of B cells, were seen in the treated fish. In some cases damage to A cells and the acinar tissue was also observed. With the restitution of normal glucose and glycogen values, the islet cells also seemed to have recuperated. Changes in glycemia, glycogen, and the islets were more pronounced in the fishes held at 24 degrees C than in those at 10 degrees C, indicating that the ambient temperature plays an important role in blood glucose homeostasis as well as insulin. 相似文献
35.
Rapid detection and identification of human adenovirus species by adenoplex, a multiplex PCR-enzyme hybridization assay
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pehler-Harrington K Khanna M Waters CR Henrickson KJ 《Journal of clinical microbiology》2004,42(9):4072-4076
Human adenoviruses (AdV) have been implicated in a wide variety of diseases and are ubiquitous in populations worldwide. These agents are of concern particularly in immunocompromised patients, children, and military recruits, resulting in severe disease or death. Clinical diagnosis of AdV is usually achieved through routine viral cell culture, which can take weeks for results. Immunofluorescence and enzyme-linked immunosorbent assay-based techniques are more timely but lack sensitivity. The ability to distinguish between the six different AdV species (A to F) is diagnostically relevant, as infections with specific AdV species are often associated with unique clinical outcomes and epidemiological features. Therefore, we developed a multiplex PCR-enzyme hybridization assay, the Adenoplex, using primers to the fiber gene that can simultaneously detect all six AdV species A through F in a single test. The limit of detection (LOD) based on the viral 50% tissue culture infective dose/ml for AdV A, B, C, D, E, and F was 10(-2), 10(-1), 10(-1), 10(-2), 10(-1), and 10(-2), respectively. Similarly, the LOD for the six DNA controls ranged from 10(2) to 10(3) copies/ml. Twelve common respiratory pathogens were tested with the Adenoplex, and no cross-reactivity was observed. We also validated our assay using clinical specimens spiked with different concentrations of AdV strains of each species type and tested by multiplex PCR and culture. The results demonstrated an overall sensitivity and specificity of Adenoplex of 100%. This assay can be completed in as few as 5 h and provides a rapid, specific, and sensitive method to detect and subtype AdV species A through F. 相似文献
36.
Gene expression patterns and gene copy number changes in dermatofibrosarcoma protuberans 总被引:5,自引:0,他引:5
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)
Linn SC West RB Pollack JR Zhu S Hernandez-Boussard T Nielsen TO Rubin BP Patel R Goldblum JR Siegmund D Botstein D Brown PO Gilks CB van de Rijn M 《The American journal of pathology》2003,163(6):2383-2395
Dermatofibrosarcoma protuberans (DFSP) is an aggressive spindle cell neoplasm. It is associated with the chromosomal translocation, t(17:22), which fuses the COL1A1 and PDGFbeta genes. We determined the characteristic gene expression profile of DFSP and characterized DNA copy number changes in DFSP by array-based comparative genomic hybridization (array CGH). Fresh frozen and formalin-fixed, paraffin-embedded samples of DFSP were analyzed by array CGH (four cases) and DNA microarray analysis of global gene expression (nine cases). The nine DFSPs were readily distinguished from 27 other diverse soft tissue tumors based on their gene expression patterns. Genes characteristically expressed in the DFSPs included PDGF beta and its receptor, PDGFRB, APOD, MEOX1, PLA2R, and PRKCA. Array CGH of DNA extracted either from frozen tumor samples or from paraffin blocks yielded equivalent results. Large areas of chromosomes 17q and 22q, bounded by COL1A1 and PDGF beta, respectively, were amplified in DFSP. Expression of genes in the amplified regions was significantly elevated. Our data shows that: 1) DFSP has a distinctive gene expression profile; 2) array CGH can be applied successfully to frozen or formalin-fixed, paraffin-embedded tumor samples; 3) a characteristic amplification of sequences from chromosomes 17q and 22q, demarcated by the COL1A1 and PDGF beta genes, respectively, was associated with elevated expression of the amplified genes. 相似文献
37.
An experimental model of carditis has been produced in the rhesus monkey by giving 12 weekly injections of a streptococcal membrane antigen. There was histological evidence of focal myocarditis, subendocardial infiltration with lymphomononuclear cells and in one animal myocardial granuloma formation. No valvular lesions were seen. Humoral immune responses monitored throughout the experiment showed that anti-heart antibodies appeared in circulation after the 2nd injection, attained maximal titres by the 6th injection, and thereafter the titres declined. The anti-membrane antibodies appeared slightly later and these titres kept rising till sacrifice. By the 6th injection there was evidence of complement consumption and appearance of circulating immune complexes. It is concluded that these immunological responses might have a role to play in the pathogenesis of carditis. 相似文献
38.
Ludwig DL Witte L Hicklin DJ Prewett M Bassi R Burtrum D Pereira DS Jimenez X Fox F Saxena B Zhou Q Ma Y Kang X Patel D Barry M Kussie P Zhu Z Russell DA Petersen WL Jury TP Gaitan-Gaitan F Moran DL Delannay X Storrs BS Tou J Zupec ME Gustafson KS McIntyre J Tarnowski SJ Bohlen P 《Human antibodies》2004,13(3):81-90
Recombinant protein production in plants such as corn is a promising means to generate high product yields at low comparable production cost. The anti-EGFR monoclonal antibody C225, cetuximab, is a well-characterized receptor antagonist antibody recently approved for the treatment of refractory colorectal cancer. We initiated a study to test and compare the functional activity of glycosylated and aglycosylated C225 produced in stable transgenic corn seed. Both corn antibodies were shown to be functionally indistinguishable from mammalian-derived C225 in demonstrating high-affinity binding to the EGF receptor, blocking of ligand-dependent signaling, and inhibiting cell proliferation. In addition, consistent with cetuximab, both corn antibodies possessed strong anti-tumor activity in vivo. Acute dose primate pharmacokinetic studies, however, revealed a marked increase in clearance for the glycosylated corn antibody, while the aglycosylated antibody possessed in vivo kinetics similar to cetuximab. This experimentation established that corn-derived receptor blocking monoclonal antibodies possess comparable efficacy to mammalian cell culture-derived antibody, and offer a cost effective alternative to large-scale mammalian cell culture production. 相似文献
39.
Changes in the magnetic resonance (MR) parameters of demyelinated neural tissue were measured in vitro using an experimental animal model. A tellurium (Te) diet was applied to weanling rats to induce the demyelination process in the sciatic nerve. The quantitative MR parameters, such as T(1), T(2) relaxation time constants and magnetization transfer (MT) were measured each day after applying the Te diet (up to 7 days) and were found to be substantially different from those of normal nerves. An increase in the average T(1) and T(2) was observed along with a decrease in the MT ratio (MTR) and the quantitative MT parameter M(0B), which describes the semisolid pool of protons. Most of the MR parameters correlated very well with the myelin fraction of neural tissue evaluated by quantitative histopathology. The T(2) relaxation spectrum provided the most efficient quantitative assessment of changes in neural tissue microstructure and its analysis resulted in a powerful tool to distinguish the processes of demyelination and inflammation. In comparison, the MT measurements were less successful. 相似文献
40.
PodurI CD Khanna A Khundmiri SJ Khaja MN Kumar KS Sugunan VS Habibullah CM Das MR 《Acta virologica》2001,45(1):1-6
The antibody profile to various proteins of hepatitis C virus (HCV) was studied in 113 patients positive for HCV RNA in various disease statuses of hepatitis C (HC). A single peptide (E2/NS1, aa 413-436 of HCV polyprotein) chosen from a conserved region at the C-terminus of the hypervariable region (HVR) HVR1 of HCV was found to be sufficient for reliable diagnosis of the infection, even in the acute phase. Six hundred and one suspected HC cases and 200 voluntary blood donors were tested by this peptide. The sensitivity of detection of HCV antibodies by this peptide did not increase with addition of peptides from other HCV proteins. Our results clearly demonstrate that antibodies to HCV envelope proteins occur in a higher percentage of the infected population than those to other proteins. This emphasizes the necessity of using representative sequences from HCV envelope proteins in diagnostic immunoassays of this viral infection. 相似文献