全文获取类型
收费全文 | 8771篇 |
免费 | 463篇 |
国内免费 | 151篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 215篇 |
妇产科学 | 650篇 |
基础医学 | 985篇 |
口腔科学 | 135篇 |
临床医学 | 1036篇 |
内科学 | 1808篇 |
皮肤病学 | 100篇 |
神经病学 | 530篇 |
特种医学 | 526篇 |
外科学 | 1083篇 |
综合类 | 197篇 |
预防医学 | 426篇 |
眼科学 | 73篇 |
药学 | 660篇 |
中国医学 | 114篇 |
肿瘤学 | 793篇 |
出版年
2023年 | 41篇 |
2022年 | 95篇 |
2021年 | 176篇 |
2020年 | 93篇 |
2019年 | 145篇 |
2018年 | 250篇 |
2017年 | 171篇 |
2016年 | 163篇 |
2015年 | 215篇 |
2014年 | 252篇 |
2013年 | 393篇 |
2012年 | 581篇 |
2011年 | 582篇 |
2010年 | 392篇 |
2009年 | 342篇 |
2008年 | 505篇 |
2007年 | 598篇 |
2006年 | 540篇 |
2005年 | 454篇 |
2004年 | 385篇 |
2003年 | 330篇 |
2002年 | 319篇 |
2001年 | 277篇 |
2000年 | 283篇 |
1999年 | 220篇 |
1998年 | 119篇 |
1997年 | 127篇 |
1996年 | 107篇 |
1995年 | 93篇 |
1994年 | 80篇 |
1993年 | 60篇 |
1992年 | 144篇 |
1991年 | 108篇 |
1990年 | 80篇 |
1989年 | 76篇 |
1988年 | 79篇 |
1987年 | 67篇 |
1986年 | 70篇 |
1985年 | 70篇 |
1984年 | 52篇 |
1983年 | 23篇 |
1982年 | 32篇 |
1981年 | 27篇 |
1980年 | 30篇 |
1979年 | 19篇 |
1978年 | 9篇 |
1977年 | 20篇 |
1976年 | 20篇 |
1975年 | 13篇 |
1971年 | 10篇 |
排序方式: 共有9385条查询结果,搜索用时 17 毫秒
81.
Although genetic analysis has convincingly shown the association possibly existing between alterations in p53 tumor suppressor gene and a broad spectrum of human tumors including prostate cancer, surprisingly little is known about ways in which p53 at the protein level is controlled. To determine factors that may play a role in its regulation and expression, changes in p53 protein was investigated by using the androgen-insensitive JCA-1, DU-145, PC-3 and the androgen-responsive LNCaP cells. With the exception of PC-3 cells in which p53 is missing, multiple distinct forms of p53 were found in the other 3 prostate cell lines. A single p53 band was detected in the JCA-1 cell extracts, whereas two and three p53 immunoreactive bands were correspondingly observed in the DU-145 and LNCaP cells. The relative abundance and distribution of the different forms of p53 in the latter two cell types varied with proliferation of cells in culture. In the presence of charcoal-stripped fetal bovine serum (cFBS), LNCaP took on the morphology of neuroendocrine cells, a phenotypic change which was accompanied by a greater than 80% reduction in p53 expression, concurrent with elimination of the two slow migrating forms of p53. Induction of apoptosis in JCA-1 cells by treatment with the retinoid 4-HPR caused the virtual disappearance of p53, which coincided with specific processing of p53 into lower molecular weight 28 kD fragments. We propose that rapid and dynamic posttranslational changes in p53 may actively participate in determining mutually exclusive functional cellular events such as proliferation, differentiation, and apoptosis. 相似文献
82.
Chang SC Sun CC Yang LS Luh KT Hsieh WC 《International journal of antimicrobial agents》1997,8(2):109-114
Methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide important pathogen in nosocomial infections. To investigate the extent of the problem in Taiwan, analysis for the period of 1981-1994 was carried out of prospective surveillance data from the National Taiwan University Hospital, a major university teaching hospital in Taiwan. The number of nosocomial MRSA infections increased from five in 1981 to 133 in 1994, and the incidence increased from 0.2 episodes/1000 discharges in 1981 to 2.9 episodes/1000 discharges in 1994. The most common infection site was surgical wounds, which accounted for 26.3% of total 577 episodes of nosocomial MRSA infections during the study period. However, bacteraemia has become more and more common during the past 14 years. MRSA infections occured more frequently in patients stayed in the burn unit and other intensive care units than in the general wards. Other than oxacillin, the resistance rate to many other antibiotics also increased in S. aureus strains causing nosocomial infections in this hospital. Vancomycin remained active to all these S. aureus strains, even until 1994. 相似文献
83.
Mainland China and Taiwan have been politically and physically segregated since 1949, and it was not until the late 1980s that limited contacts and cultural exchanges between the two societies began to take place. During their period of segregation, the two societies adopted different approaches toward gender roles. While gender equality was actively promoted in mainland China, the government in Taiwan lacked the theoretical guidance on how to achieve such equality. Gender egalitarianism in Taiwan therefore remains at the abstract or philosophical level with no specification of what gender equality means in concrete terms. Testing the hypothesis that people in mainland China have become more egalitarian than have people in Taiwan with respect to the division of marital roles, the authors investigated the differences in marital role attitudes and expected behavior among selected college students in mainland China and Taiwan. Survey responses were obtained from 185 male and 154 female students from Taiwan and 150 male and 138 female students from mainland China of different years and majors on four dimensions of marital role attitudes and six areas of traditional husband and wife role behaviors. The dimensions were determined through exploratory and confirmatory factor analyses. The data indicate that although most of the hypothesized societal differences are supported, some are not. The authors speculate that possible regressive changes in mainland China and progressive changes in Taiwan during the past decade were responsible for the discrepancy between hypotheses and results. 相似文献
84.
Chia-Ming Chu MD I-Shyan Sheen MD Chau-Ting Yeh MD Sen-Yung Hsieh MD Sun-Lung Tsai MD Yun-Fan Liaw MD 《Digestive diseases and sciences》1995,40(10):2107-2112
To evaluate the potential implication ofin vivo interferon production in the pathogenesis of different forms of acute and chronic hepatitis B virus infection, serum levels of interferon- and- were measured using immunoassay techniques in 20 patients with acute hepatitis B who subsequently cleared the virus (group Ia), 8 patients with acute hepatitis B who became HBsAg carriers (group Ib), 55 patients with chronic hepatitis B (group II), and 15 healthy controls. None of the controls had interferon- or- detectable in serum, while 15% and 100% of group Ia patients, 25% and 100% of group Ib patients, and 22% and 15% of group II patients, had raised serum levels of interferon- and-, respectively. Serum interferon- was detected significantly more frequently in group Ia and Ib patients than in controls and in group II patients. Among patients with acute hepatitis B, serum levels of interferon- and- showed no significant difference between group Ia and group Ib patients. Among patients with chronic hepatitis B, interferon- was detected significantly more frequently in patients with serum HBV-DNA (31.4% or 11/35) than in those without (5% or 1/20), whereas interferon- was detected significantly more frequently in patients with chronic active hepatitis (28% or 7/25) than in those with chronic persistent hepatitis (3.3% or 1/30). In conclusion, in acute hepatitis B, serum levels of interferon- and- did not show a significant difference between patients who subsequently cleared the virus and those who became HBsAg carriers. In chronic hepatitis B, the raised serum levels of interferon- correlated with the presence of viral replication, while the raised serum levels of interferon- correlated with the presence of histological evidence of active hepatitis. 相似文献
85.
Determination of flunarizine in rat brain by liquid chromatography-electrospray mass spectrometry 总被引:3,自引:0,他引:3
Fuh MR Hsieh CJ 《Journal of chromatography. B, Biomedical sciences and applications》1999,736(1-2):167-173
A rapid liquid chromatography-electrospray mass spectrometry (LC-ES-MS) assay for the determination of flunarizine (FZ) in rat brain has been developed. A C18 column and an isocratic elution were employed for the separation. Using post-column split, 64% of the eluent was introduced into the ES-MS system for detection. The [M+H]+ (m/z 406) and a fragmented ion (m/z 203) were detected using selected ion monitoring. The linear range of this assay was good, ranging from 0.05 to 5 microM (r2=0.99). The intra- and inter-day precisions showed relative standard deviations ranging from 1.4% to 2.0% and 1.3% to 2.9%, respectively. The application of this newly developed method was demonstrated by examining the pharmacokinetics of FZ in rat brain. 相似文献
86.
87.
88.
Hsieh BT Hsieh JF Tsai SC Lin WY Huang HT Ting G Wang SJ 《Nuclear medicine and biology》1999,26(8):741-972
Balloon angioplasty is a standard treatment for artherosclerotic coronary artery disease. However, its clinical value is reduced by a high restenosis rate. A new concept in preventing restenosis is the use of a liquid-filled balloon containing a beta-emitting radioisotope. In this study, we performed biodistribution studies of Re-188 perrhenate and Re-188 diethylenetriaminopentaacetate (DTPA) to assess the resulting organ dose values in the event of balloon rupture if these agents are used for the clinical inhibition of restenosis after percutaneous transluminal coronary angioplasty (PTCA). After injecting Re-188 preparations intravenously, rats were killed at 10 min, 30 min, 60 min, 2 h, and 6 h ( n =5 per group). Tissue concentrations were calculated and expressed as percent injected dose per gram or per milliliter (%ID/g or %ID/mL). In addition, urine excretion and thyroid gland uptake were evaluated in rats ( n=5 per group) with a gamma camera after administration of 37 MBq (1 mCi) of each agent. Our data showed that both agents were excreted primarily via urine. However, the excretion of Re-188 DTPA was much faster than that of Re-188 perrhenate via the urinary system. The biodistribution data revealed that radioactivity levels in the stomach and the thyroid gland were high in the perrhenate group but low in the Re-188 DTPA group. The concentration levels in other tissues including lung, liver, testis, muscle, and blood were low throughout this study for both agents. The thyroid radiation value in the Re-188 perrhenate group was 0.163 mGy/MBq, which was much higher than that of the Re-188 DTPA group (0.0167 mGy/MBq). The stomach radiation value was as high as 0.127 mGy/MBq for Re-188 perrhenate, compared with 0.013 mGy/MBq for Re-188 DTPA. In conclusion, in the event of balloon rupture, the release of Re-188 DTPA results in lower radiation doses than Re-188 perrhenate, especially to the thyroid gland and the stomach. Our data suggest that Re-188 DTPA is a useful radiopharmaceutical for endovascular irradiation. 相似文献
89.
Cheng M De B Almstead NG Pikul S Dowty ME Dietsch CR Dunaway CM Gu F Hsieh LC Janusz MJ Taiwo YO Natchus MG Hudlicky T Mandel M 《Journal of medicinal chemistry》1999,42(26):5426-5436
The synthesis and structure-activity relationship (SAR) studies of a series of proline-based matrix metalloproteinase inhibitors are described. The data reveal a remarkable potency enhancement in those compounds that contain an sp(2) center at the C-4 carbon of the ring relative to similar, saturated compounds. This effect was noted in compounds that contained a functionalized oxime moiety or an exomethylene at C-4, and the potencies were typically <10 nM for MMP-3 and <100 nM for MMP-1. Comparisons were then made against compounds with similar functionality where the C-4 carbon was reduced to sp(3) hybridization and the effect was typically an order of magnitude loss in potency. A comparison of compounds 14 and 34 exemplifies this observation. An X-ray structure was obtained for a stromelysin-inhibitor complex which provided insights into the SAR and selectivity trends observed within the series. In vitro intestinal permeability data for many compounds was also accumulated. 相似文献
90.
Chen YC Hung CC Lin SF Chang SC Hsieh WC 《International journal of antimicrobial agents》1996,7(1):69-74
The safety and efficacy of flomoxef and latamoxef were compared in the treatment of hospitalized patients with sepsis and/or Gram-negative bacteremia in a prospective, open-labelled clinical trial. Patients were randomized to receive 1 to 2 g intravenous doses of either flomoxef every 6 to 12 h, or latamoxef every 8 to 12 h. Data from 21 patients given flomoxef and 23 patients given latamoxef were included in the evaluation of efficacy. Flomoxef produced clinical cure and satisfactory microbiological responses in 85.7% and 100% of patients, respectively. These results were similar to those obtained with latamoxef (87% and 100%, respectively). In addition, no significant difference was found in mean age, sex, severity of infection, distribution of pathogens and focus of infection between the two groups. However, the flomoxef group included more patients with ultimately fatal diseases. Six patients given flomoxef and two patients given latamoxef developed superinfections caused by yeast, enterococci and Pseudomonas aeruginosa in the urinary tract. Mild and reversible adverse reactions probably related to flomoxef and latamoxef were noted in 14.3% and 13% of patients, respectively. The results of this study demonstrated that flomoxef is a safe and effective antimicrobial agent in the treatment of patients with sepsis and/or Gram-negative bacteremia. 相似文献