全文获取类型
收费全文 | 11329篇 |
免费 | 707篇 |
国内免费 | 127篇 |
专业分类
耳鼻咽喉 | 195篇 |
儿科学 | 74篇 |
妇产科学 | 135篇 |
基础医学 | 2080篇 |
口腔科学 | 326篇 |
临床医学 | 940篇 |
内科学 | 1828篇 |
皮肤病学 | 452篇 |
神经病学 | 1048篇 |
特种医学 | 636篇 |
外科学 | 1565篇 |
综合类 | 35篇 |
一般理论 | 2篇 |
预防医学 | 457篇 |
眼科学 | 277篇 |
药学 | 1241篇 |
中国医学 | 153篇 |
肿瘤学 | 719篇 |
出版年
2024年 | 3篇 |
2023年 | 52篇 |
2022年 | 228篇 |
2021年 | 476篇 |
2020年 | 204篇 |
2019年 | 304篇 |
2018年 | 358篇 |
2017年 | 276篇 |
2016年 | 390篇 |
2015年 | 508篇 |
2014年 | 655篇 |
2013年 | 734篇 |
2012年 | 1051篇 |
2011年 | 983篇 |
2010年 | 627篇 |
2009年 | 530篇 |
2008年 | 744篇 |
2007年 | 733篇 |
2006年 | 646篇 |
2005年 | 558篇 |
2004年 | 449篇 |
2003年 | 384篇 |
2002年 | 314篇 |
2001年 | 218篇 |
2000年 | 188篇 |
1999年 | 129篇 |
1998年 | 59篇 |
1997年 | 45篇 |
1996年 | 31篇 |
1995年 | 27篇 |
1994年 | 20篇 |
1993年 | 17篇 |
1992年 | 34篇 |
1991年 | 31篇 |
1990年 | 31篇 |
1989年 | 22篇 |
1988年 | 16篇 |
1987年 | 16篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1969年 | 2篇 |
1968年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
881.
RNA species of plant tripartite RNA viruses show distinct translational activities in vitro when the viral RNA concentration is high. However, it is not known what causes the differential translation of virion RNAs. Using an in vitro wheat germ translation system, we investigated the translation efficiencies and competitive activities of chimeric cucumber mosaic virus (CMV) RNAs that contained viral untranslated regions (UTRs) and a luciferase-coding sequence. The chimeric RNAs exhibited distinct translation efficiencies and competitive activities. For example, the translation of chimeric CMV RNA 4 was about 40-fold higher than that of chimeric CMV RNA 3 in a competitive environment. The distinct translation resulted mainly from differences in competitive activities rather than translation efficiencies of the chimeric RNAs. The differential competitive activities were specified by viral 5 UTRs, but not by 3 UTRs or viral proteins. The competitive translational activities of the 5 UTRs were as follows: RNA 4 (coat protein)>RNAs 2 and 1 (2a and 1a protein, or replicase )> RNA 3 (3a protein). 相似文献
882.
Late presentation of ureteral injury after laparoscopic surgery 总被引:10,自引:0,他引:10
OBJECTIVE: To describe clinical presentation, etiology, and treatment of ureteral injuries recognized late in women who had gynecologic laparoscopies. METHODS: We reviewed the charts of 12 women who had delayed recognition of ureteral injuries between January 1991 and December 1998. RESULTS: Patients presented with fever, hematuria, flank pain, or peritonitis between 3 and 33 days postoperatively. The mechanism of ureteral injuries was electrocoagulation in seven women, laser ablation in one, and stapler ligation in four. The sites of injury were near the inferior margin of the sacroiliac joint on excretory urogram in eight women and near the ureterovesical junction in four. Three women initially treated with internal ureteral stents were subsequently treated with ureteroneocystostomy because of progression of urinary ascites in two and a delayed ureteral stricture in one. In nine patients, attempts at ureteral stenting were unsuccessful and immediate ureteral reconstruction was done. Outcomes were good in all cases. CONCLUSION: Delayed recognition of ureteral injury after gynecologic laparoscopy was associated with serious complications, and initial treatment with ureteral stenting was not useful. We advocate early open repair for those injuries. 相似文献
883.
The effect of immediate and delayed word repetition on event-related potential in a continuous recognition task 总被引:4,自引:0,他引:4
The dissociation of immediate and delayed word repetition was studied using a continuous recognition memory task and event-related potential (ERP). Among 240 stimulus words, 40 words were not repeated, 100 were immediately repeated and 100 were repeated after 5 intervening words. Words presented only once during the experiment were referred to as new words. Subjects responded faster and more accurately to words repeated immediately than to new words and to words repeated after a delay. In terms of ERP results, immediate repetition was associated with large P300 amplitude, early P300 latency and the absence of N400, while delayed repetition was associated with small P300 amplitude, late P300 latency and the presence of N400. N400 was elicited only to new words and to those repeated after intervening words. The general morphology of the waveforms was similar for two repetition conditions until around 310 ms after the onset of stimulus. These results indicate that distinct neural systems subserve the immediate and delayed repetition effect, and that the difference between the two emerges around 310 ms poststimulus. Immediate and delayed word repetition are considered in terms of template matching and memory searching, and are possibly mediated by the parietal and left medial temporal lobes, respectively. 相似文献
884.
Kwon JW Kim IO Cheon JE Kim WS Chi JG Wang KC Yeon KM 《AJNR. American journal of neuroradiology》2001,22(7):1377-1379
We present a case of cerebellopontine (CP) angle ganglioglioma in a young child with developmental delay and no trigeminal nerve symptoms. MR imaging demonstrated a mass of homogeneous low signal intensity in the left CP angle on T1-weighted images with no enhancement with gadolinium, and of relatively homogeneous high signal intensity on T2-weighted images. 相似文献
885.
Detection of human herpesvirus 8 DNA in pemphigus and chronic blistering skin diseases 总被引:1,自引:0,他引:1
Increased incidences of Kaposi's sarcoma and lymphoid malignancies have been observed in patients with pemphigus, and the human herpesvirus 8 (HHV-8) is very strongly associated with these tumors. Because the virus may be one of the triggering factors of pemphigus, we undertook this study to screen for the presence of HHV-8 in chronic blistering skin diseases including pemphigus. A total of 45 paraffin-embedded specimens were studied using nested polymerase chain reaction (PCR) with primers to amplify a 160-base pair HHV-8 fragment. HHV-8 DNA could be detected in 7 of 9 patients with pemphigus vulagris, and 1 of 2 with pemphigus foliaceus. All specimens of other blistering skin diseases were negative for HHV-8. On sequencing PCR products, the sequences were almost identical with the prototypic sequence for HHV-8, and a few base- pair substitutions at 1086C-T and 1139A-C were detected. The results of our study suggests that HHV-8 might have trophism for pemphigus lesions. Further studies including comparison of HHV-8 DNA load in both lesional and normal skin in the same patient, serological and animal studies would be helpful to study the relationship between HHV-8 and pemphigus. 相似文献
886.
887.
Potential of adenoviral p53 gene therapy and irradiation for the treatment of malignant gliomas 总被引:2,自引:0,他引:2
Kim IA Yang YJ Yoon SC Choi IB Kay CS Kwon HC Kim CM Joe YA Kang JK Hong YK 《International journal of oncology》2001,19(5):1041-1047
We investigated the combined effects of p53 gene transfer and irradiation and its still unclear interaction mechanism in human gliomas. Four human glioma cell lines expressing mutant type p53 (U373 and A172) and wild-type p53 (D54MG and EFC-2) were transfected by adenoviral vectors bearing p53 gene at 50 multiplicity of infection. Two days after transfection, cells were irradiated (3, 6, and 9 Gy). The cytotoxicity was evaluated by clonogenic assay. The quantitative analysis of apoptosis and cell cycle analysis were performed using flow cytometry. Irradiation combined with adenoviral p53 transfection significantly increased cytotoxicity, which was additive in cell lines with wild-type p53 and more than additive in cell lines with mutant p53. The combination of two modalities increased the apoptotic population by 14% in A172 cells and 20% in D54 MG cells, which were the sum of apoptosis from each modality. Adenoviral p53 transfection increased the G1 phase fraction and concomitant decrease of radioresistant S phase fraction in A172 and D54MG cells. Our study demonstrated that p53 gene transfer combined with irradiation increased absolute cytotoxicity in human glioma cells used in this experiment. The interaction mechanism for increased cytotoxicity involved, in part, increased apoptosis and change of cell cycle profile. 相似文献
888.
Congenital smooth muscle hamartoma (CSMH) with follicular spotted appearance is a rare clinical variant of CMSH in which patients have marked perifollicular papules in the patches. A linear distribution of CSMH is also extremely rare. We report a 16-year-old Korean girl with this uncommon form of CSMH who had linearly arranged, hyperpigmented lesions with follicular papules extending from the right flank to the right lower leg from birth. Pathological findings, including immunohistochemical stains, were consistent with smooth muscle hamartoma. To date, there are only four reports on this rare, follicular form and one report on the linear form of CSMH in the literature. This paper describes the first combined occurrence of follicular spotted lesions and linear arrangement in CSMH. 相似文献
889.
J Y Kwon J C Shin J W Lee J K Lee S P Kim J G Rha 《International journal of gynaecology and obstetrics》2007,96(2):85-88
OBJECTIVE: Idiopathic thrombocytopenic purpura (ITP) and gestational thrombocytopenia (GT) are common causes of thrombocytopenia during pregnancy. Despite an ever-increasing experience with these disorders, differentiation between the two entities still remains a diagnostic challenge. The current study attempted to identify the antenatal predictors of ITP for pregnant women. METHODS: Between January 1999 and June 2005, a total of 58 pregnant women with a presumptive diagnosis of either ITP or GT were recruited for the study. All of them had platelet counts of less than 100 x 10(9)/L. The predictors of ITP were evaluated by comparison between the two disorders. RESULTS: The detection of thrombocytopenia prior to 28 weeks of gestation and platelet counts <50 x 10(9)/L at its diagnosis remained independently predictive of ITP (P<0.001 and P=0.004, respectively). The combined analysis of these two factors provided a 96.0% sensitivity and a specificity of 75.8%. CONCLUSION: The onset time of thrombocytopenia and platelet count at its presentation remain the strongest predictors of ITP for pregnant women. The combination model using these factors may be useful for the early prediction of ITP. 相似文献
890.
Ubiquitin conjugation by the N-end rule pathway and mRNAs for its components increase in muscles of diabetic rats 总被引:6,自引:0,他引:6 下载免费PDF全文
Lecker SH Solomon V Price SR Kwon YT Mitch WE Goldberg AL 《The Journal of clinical investigation》1999,104(10):1411-1420
Insulin deficiency (e.g., in acute diabetes or fasting) is associated with enhanced protein breakdown in skeletal muscle leading to muscle wasting. Because recent studies have suggested that this increased proteolysis is due to activation of the ubiquitin-proteasome (Ub-proteasome) pathway, we investigated whether diabetes is associated with an increased rate of Ub conjugation to muscle protein. Muscle extracts from streptozotocin-induced insulin-deficient rats contained greater amounts of Ub-conjugated proteins than extracts from control animals and also 40-50% greater rates of conjugation of (125)I-Ub to endogenous muscle proteins. This enhanced Ub-conjugation occurred mainly through the N-end rule pathway that involves E2(14k) and E3alpha. A specific substrate of this pathway, alpha-lactalbumin, was ubiquitinated faster in the diabetic extracts, and a dominant negative form of E2(14k) inhibited this increase in ubiquitination rates. Both E2(14k) and E3alpha were shown to be rate-limiting for Ub conjugation because adding small amounts of either to extracts stimulated Ub conjugation. Furthermore, mRNA for E2(14k) and E3alpha (but not E1) were elevated 2-fold in muscles from diabetic rats, although no significant increase in E2(14k) and E3alpha content could be detected by immunoblot or activity assays. The simplest interpretation of these results is that small increases in both E2(14k) and E3alpha in muscles of insulin-deficient animals together accelerate Ub conjugation and protein degradation by the N-end rule pathway, the same pathway activated in cancer cachexia, sepsis, and hyperthyroidism. 相似文献