全文获取类型
收费全文 | 9926篇 |
免费 | 677篇 |
国内免费 | 34篇 |
专业分类
耳鼻咽喉 | 139篇 |
儿科学 | 198篇 |
妇产科学 | 193篇 |
基础医学 | 1159篇 |
口腔科学 | 318篇 |
临床医学 | 1009篇 |
内科学 | 2089篇 |
皮肤病学 | 168篇 |
神经病学 | 1016篇 |
特种医学 | 775篇 |
外科学 | 1820篇 |
综合类 | 55篇 |
一般理论 | 1篇 |
预防医学 | 425篇 |
眼科学 | 204篇 |
药学 | 457篇 |
中国医学 | 4篇 |
肿瘤学 | 607篇 |
出版年
2023年 | 115篇 |
2022年 | 205篇 |
2021年 | 355篇 |
2020年 | 228篇 |
2019年 | 324篇 |
2018年 | 359篇 |
2017年 | 269篇 |
2016年 | 305篇 |
2015年 | 352篇 |
2014年 | 466篇 |
2013年 | 464篇 |
2012年 | 724篇 |
2011年 | 715篇 |
2010年 | 417篇 |
2009年 | 446篇 |
2008年 | 532篇 |
2007年 | 539篇 |
2006年 | 427篇 |
2005年 | 407篇 |
2004年 | 334篇 |
2003年 | 330篇 |
2002年 | 265篇 |
2001年 | 164篇 |
2000年 | 174篇 |
1999年 | 167篇 |
1998年 | 58篇 |
1997年 | 67篇 |
1996年 | 56篇 |
1995年 | 27篇 |
1994年 | 30篇 |
1993年 | 31篇 |
1992年 | 82篇 |
1991年 | 103篇 |
1990年 | 86篇 |
1989年 | 69篇 |
1988年 | 91篇 |
1987年 | 79篇 |
1986年 | 61篇 |
1985年 | 66篇 |
1984年 | 57篇 |
1983年 | 32篇 |
1981年 | 20篇 |
1980年 | 17篇 |
1979年 | 50篇 |
1978年 | 23篇 |
1976年 | 23篇 |
1975年 | 30篇 |
1974年 | 30篇 |
1969年 | 14篇 |
1932年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
Wanitchaya Kittikraisak Taweewun Hunsawong Somsak Punjasamanvong Thanapat Wongrapee Patama Suttha Phunlerd Piyaraj Chaniya Leepiyasakulchai Chuleeekorn Tanathitikorn Pornsak Yoocharoen Anthony R. Jones Duangrat Mongkolsirichaikul Matthew Westercamp Eduardo AzzizBaumgartner Joshua A. Mott Suthat Chottanapund 《Influenza and other respiratory viruses》2022,16(4):662
BackgroundWe examined SARS‐CoV‐2 anti‐spike 1 IgG antibody levels following COVID‐19 vaccination (AstraZeneca [AZ], Sinovac [SV], Pfizer‐BioNTech [PZ]) among Thai healthcare providers.MethodsBlood specimens were tested using enzyme‐linked immunosorbent assay. We analyzed seven vaccination regimens: (1) one dose of AZ or SV, (2) two doses of homologous (2AZ, 2SV) or heterologous (1AZ + 1PZ) vaccines, and (3) three doses of heterologous vaccines (2SV + 1AZ, 2SV + 1PZ). Differences in antibody levels were assessed using Kruskal–Wallis statistic, Mann–Whitney test, or Wilcoxon matched‐pairs signed‐rank test. Antibody kinetics were predicted using fractional polynomial regression.ResultsThe 563 participants had median age of 39 years; 92% were female; 74% reported no underlying medical condition. Antibody levels peaked at 22–23 days in both 1AZ and 2SV vaccinees and dropped below assay''s cutoff for positive (35.2 binding antibody units/ml [BAU/ml]) in 55 days among 1AZ vaccinees compared with 117 days among 2SV vaccinees. 1AZ + 1PZ vaccination regimen was highly immunogenic (median 2279 BAU/ml) 1–4 weeks post vaccination. 2SV + 1PZ vaccinees had significantly higher antibody levels than 2SV + 1AZ vaccinees 4 weeks post vaccination (3423 vs. 2105 BAU/ml; p‐value < 0.01), and during weeks 5–8 (3656 vs. 1072 BAU/ml; p‐value < 0.01). Antibodies peaked at 12–15 days in both 2SV + 1PZ and 2SV + 1AZ vaccinees, but those of 2SV + 1AZ declined more rapidly and dropped below assay''s cutoff in 228 days while those of 2SV + 1PZ remained detectable.Conclusions1AZ + 1PZ, 2SV + 1AZ, and 2SV + 1PZ vaccinees had substantial IgG levels, suggesting that these individuals likely mounted sufficient anti‐S1 IgG antibodies for possible protection against SARS‐CoV‐2 infection. 相似文献
94.
Paul M Garrett Joshua P White Simon Dennis Stephan Lewandowsky Cheng-Ta Yang Yasmina Okan Andrew Perfors Daniel R Little Anastasia Kozyreva Philipp Lorenz-Spreen Takashi Kusumi Yoshihisa Kashima 《JMIR Public Health and Surveillance》2022,8(7)
BackgroundIn response to the COVID-19 pandemic, countries are introducing digital passports that allow citizens to return to normal activities if they were previously infected with (immunity passport) or vaccinated against (vaccination passport) SARS-CoV-2. To be effective, policy decision-makers must know whether these passports will be widely accepted by the public and under what conditions. This study focuses attention on immunity passports, as these may prove useful in countries both with and without an existing COVID-19 vaccination program; however, our general findings also extend to vaccination passports.ObjectiveWe aimed to assess attitudes toward the introduction of immunity passports in six countries, and determine what social, personal, and contextual factors predicted their support.MethodsWe collected 13,678 participants through online representative sampling across six countries—Australia, Japan, Taiwan, Germany, Spain, and the United Kingdom—during April to May of the 2020 COVID-19 pandemic, and assessed attitudes and support for the introduction of immunity passports.ResultsImmunity passport support was moderate to low, being the highest in Germany (775/1507 participants, 51.43%) and the United Kingdom (759/1484, 51.15%); followed by Taiwan (2841/5989, 47.44%), Australia (963/2086, 46.16%), and Spain (693/1491, 46.48%); and was the lowest in Japan (241/1081, 22.94%). Bayesian generalized linear mixed effects modeling was used to assess predictive factors for immunity passport support across countries. International results showed neoliberal worldviews (odds ratio [OR] 1.17, 95% CI 1.13-1.22), personal concern (OR 1.07, 95% CI 1.00-1.16), perceived virus severity (OR 1.07, 95% CI 1.01-1.14), the fairness of immunity passports (OR 2.51, 95% CI 2.36-2.66), liking immunity passports (OR 2.77, 95% CI 2.61-2.94), and a willingness to become infected to gain an immunity passport (OR 1.6, 95% CI 1.51-1.68) were all predictive factors of immunity passport support. By contrast, gender (woman; OR 0.9, 95% CI 0.82-0.98), immunity passport concern (OR 0.61, 95% CI 0.57-0.65), and risk of harm to society (OR 0.71, 95% CI 0.67-0.76) predicted a decrease in support for immunity passports. Minor differences in predictive factors were found between countries and results were modeled separately to provide national accounts of these data.ConclusionsOur research suggests that support for immunity passports is predicted by the personal benefits and societal risks they confer. These findings generalized across six countries and may also prove informative for the introduction of vaccination passports, helping policymakers to introduce effective COVID-19 passport policies in these six countries and around the world. 相似文献
95.
Philipp Saiko Geraldine Graser Benedikt Giessrigl Andreas Lackner Michael Grusch Georg Krupitza Arijit Basu Barij Nayan Sinha Venkatesan Jayaprakash Walter Jaeger Monika Fritzer-Szekeres Thomas Szekeres 《Biochemical pharmacology》2011,(1):50
Ribonucleotide reductase (RR; EC 1.17.4.1) is responsible for the de novo conversion of ribonucleoside diphosphates into deoxyribonucleoside diphosphates, which are essential for DNA replication. RR is upregulated in tumor cells and therefore considered to be an excellent target for cancer chemotherapy.ABNM-13 (N-hydroxy-2-(anthracene-2-yl-methylene)-hydrazinecarboximidamide), a novel N-hydroxy-N′-aminoguanidine has been designed to inhibit RR activity using 3D molecular space modeling techniques. In this study, we evaluated its effect on human HL-60 promyelocytic leukemia cells. ABNM-13 proved to be a potent inhibitor of RR which was displayed by significant alterations of deoxyribonucleoside triphosphate (dNTP) pool balance and a highly significant decrease of incorporation of radiolabeled cytidine into DNA of HL-60 cells. Diminished RR activity caused replication stress which was consistent with activation of Chk1 and Chk2, resulting in downregulation/degradation of Cdc25A. In contrast, Cdc25B was upregulated, leading to dephosphorylation and activation of Cdk1. The combined disregulation of Cdc25A and Cdc25B was the most likely cause for ABNM-13 induced S-phase arrest. Finally, we combined ABNM-13 with the first-line antileukemic agent arabinofuranosylcytosine (Ara-C) and found that ABNM-13 synergistically potentiated the antineoplastic effects of Ara-C.Due to these promising results, ABNM-13 deserves further preclinical and in vivo testing. 相似文献
96.
97.
Schmidt P Staboulidou I Soergel P Wüstemann M Hillemanns P Scharf A 《Archives of gynecology and obstetrics》2007,275(6):469-474
Objective The individual risk assessment of fetal Down’s syndrome based on measurement of nuchal translucency (NT) according to Nicolaides,
optionally complemented by the determination of PAPP-A and free beta HCG has progressively supplanted other search strategies
for fetal aneuploidies. It could be shown that this diagnostic strategy equally detects other numeric aneuploidies at a comparable
rate. A positive test result is also predictive for the presence of a fetal malformation. In this field, several computer
programs are available for clinical use. The objective of our study was to re-evaluate the first consecutive 1463 NT-risk
calculations determined by Nicolaides’ method and to compare the risk calculation to the JOY software (NT-risk calculation
module, JOY Patient Database) introduced in 2002.
Material and methods At the Department of Obstetrics and Gynecology, Hannover Medical School, 1463 consecutive complete data sets comprising first
trimester screening performed between May 2, 2000 and June 26, 2003 and corresponding fetal outcome were analysed using risk
assessment based on the Nicolaides method (PIA Fetal Database NT-Module) and compared with the risk evaluation as determined
by the JOY software (JOY Patient Database NT module). A risk exceeding 1:300 was considered to indicate the need for further
invasive testing. In a first step, only cytogenetically detectable chromosomal aberrations were analysed. Then, a second evaluation
including fetal malformations was performed.
Results Among the 1463 cases, 1445 (98.77%) fetuses revealed to be cytogenetically healthy. Both softwares showed identical detection
rates at the genetic and somatic level:13 cases of Down-Syndrome (0.89%), 2 cases of trisomy 18 (0.14%), one case of triploidy,
one Turner-Syndrome, one Klinefelter-Syndrome (0.07% each) were detected. A positive test result was found in 15 cases ending
in a spontaneous abortion, intrauterine death or peripartum death (1.03%) and in 22 cases of fetal malformation (1.50%). At
the level of genetic detection the test positive rate dropped from 92 (PIA) to 71 (JOY) (-22.8%). At the level of combined
adverse outcome the test positive rate was reduced from 100 (PIA) to 76 (JOY) (-22.0%), thus yielding in a marked improvement
of the characteristic test performance parameters.
Conclusion The novel, recently developed JOY software package allowed reliable evaluation of the risk for aneuploidy with increased specificity
whereas sensitivity was unchanged. Our data suggest an improvement of the screening for aneuploidy when using this novel software:
With an identical detection rate, the number of unnecessary invasive measures may be reduced. 相似文献
98.
Staboulidou I Soergel P Schmidt P Steinborn A Hillemanns P Scharf A 《Archives of gynecology and obstetrics》2007,276(1):35-42
Introduction
The proper function of the fetal heart is indispensable for the fetal development and the normal fetal growth. For prenatal medicine, Doppler sonography offers the possibility of a non-invasive method to examine the fetal cardiovascular function under normal and pathological circumstances. The role of the Doppler sonography is to identify those fetuses who have a high risk factor for developing a pre- or intrapartual asphyxia and therefore have to be delivered promptly. This study aimed at evaluating the clinical value of the intracardiac Doppler sonography (IDS) and at scrutinizing its usefulness during the supervision of the pregnancy of intrauterine growth restricted (IUGR) fetuses.Materials and methods
In a prospective research at the Medical School of Hanover, fetal IDS was applied to 174 pregnant women between the 21 and 37 weeks of gestation (WG). The e-wave and the a-wave, the E/A ratio, and the TVI (time velocity integral) were measured at the atrioventricular (AV) valves. The PV (peak velocity) as well as the TVI were determined at both the aortic and the pulmonary valve. Normal range curves were compiled for all measured parameters.Results
Alongside a control group with untroubled gravidity, which consisted of 153 patients, IUGR fetuses, who formed a collective of 21 patients, were Doppler sonographically examined.While the gestational age advanced, an increase of both the e-wave and the a-wave above the AV-valves could be ascertained, which lead to an E/A ratio <1. Above the semilunar valves there was indicated a slight steady increase of the TPV, the PV as well as the TVI. Normal range curves, which largely correspond to those described in the literature, were compiled for the collective of the pregnancies without pathological findings (n = 153). In comparison to the standard collective, there were no significant differences from the collective of the growth restricted fetuses (n = 21).Conclusion
A temporal informational advantage of pathological intracardiac Doppler values for high risk pregnancies (IUGR) could not be retraced in the examined collective.Doppler sonography traces acute and chronic deficits, which are indicated by hemodynamic changes of the fetus’s blood supply. The clinical importance of IDS as regards dystrophic fetuses has to be ascertained in continuative studies: In the stage of compensatory placental insufficiency (IUGR, arterial Doppler without ARED-flow, venous Doppler without pathological findings) the IDS cannot provide an informational advantage. Contrastingly, the diagnostic potential of the IDS as a screening method of fetal cardiac insufficiency during decompensative placental insufficiency (IUGR, arterial Doppler with ARED-flow, venous Doppler normal or pathological) remains indistinct and should therefore be prospectively evaluated within this high risk group and contrastingly compared to the significance of the venous Doppler sonography (informational advantage?).99.
100.
A. Simons Fritz Händel Langendorff Josef Frank F. Eillinger Happel Zwerg Fried Walter Schaefer Hedfeld E. Philipp Wehefritz Englmann 《Journal of cancer research and clinical oncology》1932,36(5-6):125-128
Ohne Zusammenfassung 相似文献