全文获取类型
收费全文 | 5608篇 |
免费 | 428篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 67篇 |
儿科学 | 223篇 |
妇产科学 | 91篇 |
基础医学 | 760篇 |
口腔科学 | 443篇 |
临床医学 | 492篇 |
内科学 | 1214篇 |
皮肤病学 | 179篇 |
神经病学 | 406篇 |
特种医学 | 452篇 |
外科学 | 563篇 |
综合类 | 31篇 |
预防医学 | 445篇 |
眼科学 | 96篇 |
药学 | 348篇 |
1篇 | |
中国医学 | 43篇 |
肿瘤学 | 231篇 |
出版年
2023年 | 52篇 |
2022年 | 83篇 |
2021年 | 176篇 |
2020年 | 130篇 |
2019年 | 156篇 |
2018年 | 220篇 |
2017年 | 145篇 |
2016年 | 187篇 |
2015年 | 219篇 |
2014年 | 290篇 |
2013年 | 348篇 |
2012年 | 365篇 |
2011年 | 361篇 |
2010年 | 220篇 |
2009年 | 245篇 |
2008年 | 243篇 |
2007年 | 301篇 |
2006年 | 226篇 |
2005年 | 187篇 |
2004年 | 168篇 |
2003年 | 143篇 |
2002年 | 120篇 |
2001年 | 85篇 |
2000年 | 74篇 |
1999年 | 67篇 |
1998年 | 123篇 |
1997年 | 135篇 |
1996年 | 128篇 |
1995年 | 96篇 |
1994年 | 95篇 |
1993年 | 103篇 |
1992年 | 46篇 |
1991年 | 37篇 |
1990年 | 36篇 |
1989年 | 59篇 |
1988年 | 52篇 |
1987年 | 33篇 |
1986年 | 40篇 |
1985年 | 42篇 |
1984年 | 24篇 |
1983年 | 22篇 |
1982年 | 21篇 |
1981年 | 37篇 |
1980年 | 22篇 |
1979年 | 16篇 |
1978年 | 9篇 |
1977年 | 24篇 |
1976年 | 19篇 |
1975年 | 6篇 |
1967年 | 8篇 |
排序方式: 共有6085条查询结果,搜索用时 468 毫秒
41.
DNA vaccine encoding human immunodeficiency virus-1 Gag, targeted to the major histocompatibility complex II compartment by lysosomal-associated membrane protein, elicits enhanced long-term memory response 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Antigen presentation by major histocompatibility complex type II (MHC II) molecules and activation of CD4+ helper T cells are critical for the generation of immunological memory. We previously described a DNA vaccine encoding human immunodeficiency virus-1 p55Gag as a chimera with the lysosome-associated membrane protein (LAMP/gag). The LAMP/gag chimera protein traffics to the MHC II compartment of transfected cells and elicits enhanced immune responses as compared to a DNA vaccine encoding native gag not targeted to the MHC II compartment. We have now investigated the long-term responses of immunized mice and show that the LAMP/gag DNA vaccine promotes long-lasting B cell- and CD4+ and CD8+ T-cell memory responses induced by DNA encoding non-targeted Gag decay rapidly and elicit very low or undetectable levels of gag DNA is sufficient to generate T-cell memory. Following this initial priming immunization with LAMP/gag DNA, booster immunizations with native gag DNA or the LAMP/gag chimera are equally efficient in eliciting B- and T-cell secondary responses, results in accordance with observations that secondary expansion of CD8+ cells in the boost phase does not require additional CD4+ help. These findings underscore the significance of targeting DNA-encoded vaccine antigens to the MHC II processing compartments for induction of long-term immunological memory. 相似文献
42.
Variability of skin temperature in the waking monkey 总被引:3,自引:0,他引:3
43.
Marques da Silva SH Queiroz-Telles F Colombo AL Blotta MH Lopes JD Pires De Camargo Z 《Journal of clinical microbiology》2004,42(6):2419-2424
Paracoccidioidomycosis (PCM) is a systemic fungal disease that is particularly important among individuals living and working in rural areas of endemicity in Latin America. Detection of anti-Paracoccidioides brasiliensis antibodies is of limited value due to false-negative results. Detection of P. brasiliensis-gp43 circulating antigen is a practical approach for a specific diagnosis of the disease. In a previous study we described an inhibition enzyme-linked immunosorbent assay able to detect the 43-kDa P. brasiliensis antigen in sera of 100% of patients with the acute form of PCM and in 95.31 and 100% of patients with the chronic multifocal and unifocal forms of PCM. To investigate its potential application for the follow-up of PCM patients during treatment, antigen levels were monitored at regular intervals for up 8 to 12 months in serum samples from 23 patients. The results showed that treatment with itraconazole resulted in decreasing levels of circulating gp43 that were correlated with the reduction of anti-gp43 antibodies. It was also observed that by the end of 12 months of treatment gp43 levels were <5 microg/ml in all patients. 相似文献
44.
45.
Gontijo AM Marcondes JP Elias FN de Oliveira ML de Lima RO Salvadori DM de Camargo JL 《Environmental and molecular mutagenesis》2002,40(3):190-199
In order to determine if patients with a history of previous urothelial cell carcinoma (UCC) but with current normal urinary cytology have DNA damage in urothelial cells, the single-cell gel electrophoresis (comet) assay was conducted with cells obtained by urinary bladder washings from 44 patients (28 with a history of previous UCC). Increased DNA damage was observed in cytologically "normal" urothelial cells of patients with a history of UCC when compared with referents with no similar history and after correcting the data for smoking status and age (P < 0.018). Increased DNA damage also correlated with the highest tumor grade, irrespective of time or course of the disease after clinical intervention (Kendall tau correlation, 0.37, P = 0.016). Moreover, aneuploidy, as assessed by DNA content ratio (DCR; 75th/25th percentile of total DNA fluorescence of 50 comets/patient) was unaltered by smoking status, but increased with UCC grade: 1.39 +/- 0.12 (median +/- 95% confidence interval; referents); 1.43 +/- 0.11 (Grade I UCC; P = 0.264, against referents); 1.49 +/- 0.16 (Grade II UCC; P = 0.057); 1.57 +/- 0.16 (Grade III UCC; P = 0.003). Micronucleated urothelial cells (MNC) were also scored on Giemsa-stained routine cytological smears and were found not to correlate with DNA damage or DCR. MNC frequencies were higher for patients with a history of UCC and/or smoking than referents with neither history, but there was no statistical difference between groups. Taken together, these results suggest that the normal-appearing urothelium of patients resected for UCC still harbor genetically unstable cells. 相似文献
46.
de Oliveira NM Vaca Sánchez R Rodriguez Fiesta S Lopez Salgado T Rodríguez R Bethencourt JC Blanes Zamora R 《Human reproduction (Oxford, England)》2004,19(2):262-265
BACKGROUND: There are few reports of pregnancy using immotile sperm, and none using a purely mechanical assessment of viability. METHODS: In this pilot study, we retrospectively analysed 66 cycles in 61 patients with determinant male factor, recording rates of fertilization, implantation, normal pregnancy and take-home babies achieved with ICSI. Sperm selection was based on morphologically normal appearance under the inverted microscope. Viability of immotile spermatozoa was assessed by the mechanical touch technique to observe tail flexibility and tail shape recovery. RESULTS: Of 17 ICSI cycles using frozen-thawed testicular sperm, six microinjected with immotile and 11 with motile sperm, we achieved fertilization rates of 65.7 and 74.3%, respectively, and five pregnancies (two and three, respectively). Of 49 ICSI cycles using fresh testicular sperm, 10 microinjected with immotile and 39 with motile sperm, we achieved fertilization rates of 73.4 and 64.4%, respectively, and 12 pregnancies (three and nine, respectively). CONCLUSIONS: Immotile (fresh and frozen-thawed) testicular sperm of normal morphological appearance can be used to achieve clinical pregnancy with ICSI. Our results strongly suggest that immotile sperm viability can be assessed by the mechanical touch technique. 相似文献
47.
48.
Permeation of human ovarian tissue with cryoprotective agents in preparation for cryopreservation 总被引:18,自引:10,他引:18
Newton H; Fisher J; Arnold JR; Pegg DE; Faddy MJ; Gosden RG 《Human reproduction (Oxford, England)》1998,13(2):376-380
The recent improvements in the treatment of cancer by chemo- and
radiotherapy have led to a significant increase in the survival rates of
patients with malignant disease, but at the expense of distressing side
effects. One major problem, especially for younger patients, is that
aggressive therapy destroys a significant proportion of the follicular
population, which can result in either temporary or permanent infertility.
Freeze-banking pieces of ovarian cortex prior to treatment is one strategy
for preserving fecundity. When the patient is in remission, fertility
could, theoretically, be restored by autografting the thawed tissue at the
orthotopic site or by growing isolated follicles to maturity in vitro.
Recent studies have found good follicular survival in frozen-thawed human
ovarian tissue but to optimize the process an effective cryopreservation
method needs to be developed. An essential part of such a technique is to
permeate the tissue with a cryoprotectant to minimize ice formation and the
extent of this equilibration is an important determinant of post-thaw
cellular survival. In the current study, we have investigated the diffusion
of four cryoprotective agents into human tissue at both 4 degrees C and 37
degrees C. We have also studied the effect of adding different
concentrations of the non penetrating cryoprotective agent, sucrose, to the
freezing media using the release of lactate dehydrogenase as a measure of
its protective effect. At 4 degrees C propylene glycol and glycerol
penetrated the tissue significantly slower than either ethylene glycol or
dimethyl sulphoxide. At the higher temperature of 37 degrees C all four
cryoprotectants penetrated at a faster rate, however concern about enhanced
toxicity prevents the use of these conditions in practice. Thus, the
results suggest that the best method of preparing tissue for freezing is
exposure for 30 min to 1.5 M solutions of ethylene glycol or dimethyl
sulphoxide at 4 degrees C; this achieved a mean tissue concentration that
was almost 80% that of the bathing solution. We also report that the
addition of low concentrations of sucrose to the freezing medium does not
have a significant protective effect against freezing injury.
相似文献
49.
Stein TP; Oram-Smith JC; Leskiw MJ; Wallace HW; Long LC; Leonard JM 《The American journal of physiology》1976,230(5):1321-1325
50.
Fever and antipyresis in the lizard Dipsosaurus dorsalis 总被引:2,自引:0,他引:2