全文获取类型
收费全文 | 7760篇 |
免费 | 430篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 51篇 |
儿科学 | 172篇 |
妇产科学 | 68篇 |
基础医学 | 1329篇 |
口腔科学 | 265篇 |
临床医学 | 540篇 |
内科学 | 1598篇 |
皮肤病学 | 229篇 |
神经病学 | 971篇 |
特种医学 | 458篇 |
外科学 | 1011篇 |
综合类 | 44篇 |
一般理论 | 2篇 |
预防医学 | 280篇 |
眼科学 | 101篇 |
药学 | 605篇 |
中国医学 | 11篇 |
肿瘤学 | 492篇 |
出版年
2022年 | 30篇 |
2021年 | 65篇 |
2020年 | 73篇 |
2019年 | 93篇 |
2018年 | 116篇 |
2017年 | 100篇 |
2016年 | 118篇 |
2015年 | 160篇 |
2014年 | 248篇 |
2013年 | 307篇 |
2012年 | 410篇 |
2011年 | 430篇 |
2010年 | 311篇 |
2009年 | 297篇 |
2008年 | 448篇 |
2007年 | 489篇 |
2006年 | 494篇 |
2005年 | 517篇 |
2004年 | 476篇 |
2003年 | 506篇 |
2002年 | 511篇 |
2001年 | 108篇 |
2000年 | 104篇 |
1999年 | 150篇 |
1998年 | 133篇 |
1997年 | 101篇 |
1996年 | 94篇 |
1995年 | 79篇 |
1994年 | 75篇 |
1993年 | 59篇 |
1992年 | 64篇 |
1991年 | 59篇 |
1990年 | 53篇 |
1989年 | 40篇 |
1988年 | 38篇 |
1987年 | 58篇 |
1986年 | 32篇 |
1985年 | 44篇 |
1984年 | 33篇 |
1983年 | 33篇 |
1982年 | 43篇 |
1981年 | 35篇 |
1980年 | 38篇 |
1978年 | 39篇 |
1977年 | 33篇 |
1976年 | 42篇 |
1975年 | 31篇 |
1974年 | 43篇 |
1973年 | 35篇 |
1970年 | 33篇 |
排序方式: 共有8227条查询结果,搜索用时 31 毫秒
41.
42.
D Komiotis C T Lim J P Dieter G C Le Breton D L Venton 《Journal of medicinal chemistry》1992,35(16):3033-3039
Previous observations implicating PgH2 as a direct activator of platelets suggested that derivatives of U46619, a well-characterized TxA2 receptor agonist having structural homology with PgH2, might possess antiplatelet activity. The present work describes the synthesis of [1S-(1 alpha,2 beta,3 alpha,4 alpha)]-3-[(tetrahydropyranyloxy)methyl]- 2-[2-[(triphenylmethyl)oxy]ethyl]-5-oxabicyclo[2.2.1]heptane (14) a potentially useful intermediate for the synthesis of various epoxymethano derivatives. The latter was converted to [1S-(1 alpha,2 beta (Z),3 alpha,4 alpha)]-7-[3-[[2- [(phenylamino)carbonyl]-hydrazino]methyl]-5-oxabicylo[2.2.1]hept-2 - yl]-5-heptenoic acid (23), an epoxymethano derivative of PgH2 containing a hydrazide lower side chain as previously used in the TxA2 antagonist, SQ 29,548. The intermediate 14 was also converted to [1S-(1 alpha,2 beta (Z),3 alpha,4 alpha)]-7- [3-[(hexylamino)methyl]-5-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid (25) which contained a simple aza side chain as used in earlier antagonists. Derivatives 23 and 25 appeared to be specific antagonists of the human platelet TxA2 receptor as evidenced by their inhibition of U46619 (1.5 microM) induced aggregation of human platelet rich plasma (IC50 = 22 and 7 microM, respectively), while having little effect on ADP (2 microM) induced aggregation at much higher concentrations. In addition, one of these derivatives, the bicycloamine 25, was shown to compete for [3H]U46619 binding to washed human platelets with an IC50 value of 25 microM, supporting the notion that these derivatives were acting at the thromboxane receptor. However, the potency of these derivatives was less than for previously reported TxA2 antagonists, suggesting that simple linear combinations of functionality from molecules active at the human platelet thromboxane receptor will be of limited predictive value. 相似文献
43.
Bernard Swerdlow M.D. Clinical Assistant Professor Medical Director John Nathan Dieter B.S. Research/Clinical Assistant 《Headache》1987,27(1):10-15
SYNOPSIS
These experiments investigate thermographic patterns in the posterior cervical/thoracic (PCT) region of 530headache patients and 30 headache/injury-free volunteers. The study examines: The longitudinal persistence ofProximal and Distal patterns; three distinct midline patterns (PCT I, II, and III); and their correlation with diagnosis,injury, and pain.
Twenty-four (80%) of 30 randomly selected subjects displayed unchanged Proximal patterns at the meanobservation period of 5.5 months. PCT pattern fluctuations occurred in 13/30 (43.3%) subjects. The distinctivenessof each subject's Proximal and Distal patterns was verified by blind calling of thermogram pairs. Patternpersistence was validated with alcohol spray-Patterns were identical regardless of using a 0.5°C or 1.0°Ctemperature setting. Temperature settings of 1.0°C yielded more distinct Proximal and Distal patterns.
Chi square analysis determined that there was no significant difference in the number of PCT III patterns in theexperimental or control groups.
In conclusion, it appears that Proximal and Distal Patterns may be consistent over time and individually unique,but that PCT patterns fluctuate and, therefore, do not correlate with chronic headaches. 相似文献
These experiments investigate thermographic patterns in the posterior cervical/thoracic (PCT) region of 530headache patients and 30 headache/injury-free volunteers. The study examines: The longitudinal persistence ofProximal and Distal patterns; three distinct midline patterns (PCT I, II, and III); and their correlation with diagnosis,injury, and pain.
Twenty-four (80%) of 30 randomly selected subjects displayed unchanged Proximal patterns at the meanobservation period of 5.5 months. PCT pattern fluctuations occurred in 13/30 (43.3%) subjects. The distinctivenessof each subject's Proximal and Distal patterns was verified by blind calling of thermogram pairs. Patternpersistence was validated with alcohol spray-Patterns were identical regardless of using a 0.5°C or 1.0°Ctemperature setting. Temperature settings of 1.0°C yielded more distinct Proximal and Distal patterns.
Chi square analysis determined that there was no significant difference in the number of PCT III patterns in theexperimental or control groups.
In conclusion, it appears that Proximal and Distal Patterns may be consistent over time and individually unique,but that PCT patterns fluctuate and, therefore, do not correlate with chronic headaches. 相似文献
44.
Dieter Ulrich Preiss Delawer Abdullah Bruno Eberspcher Karlheinz Wilhelm 《Thrombosis research》1992,65(6):677-686
In a prospective clinical trial the risk of infection after application of virus inactivated antithrombin III concentrate ANTITHROMBIN III IMMUNO (AT III) was investigated in patients undergoing cardiovascular surgery. The study was conducted according to the recommendations of the International Committee on Thrombosis and Hemostasis (ICTH), with the exception that most patients required additional blood products as well as AT III.
Twenty-seven patients were eligible to test for the risk of acquiring hepatitis B. Twenty-six patients could be evaluated in terms of hepatitis NANB transmission considering ALT-levels whereas 20 patients could be tested for anti-HCV one year after surgery. Samples from 78 patients could be monitored for anti-HIV-1. None of these patients showed any signs of infection. AT III IMMUNO seems to be an antithrombin III concentrate with low or absent infectivity. 相似文献
45.
46.
Magdolna Hornyak Hans-Peter Hundemer Deborah Quail Dieter Riemann Ulrich Voderholzer Claudia Trenkwalder 《Clinical neurophysiology》2007,118(7):1532-1537
OBJECTIVE: To evaluate the relationship of the severity of restless legs syndrome (RLS) as assessed by a subjective, patient-rated scale (International RLS Study Group Rating Scale, IRLS), and of periodic leg movements in sleep (PLMS) as an objective parameter, in two different patient populations. METHODS: Data of 200 unmedicated patients with idiopathic RLS were evaluated. Group 1 (n=100) consisted of selected patients participating in the Pergolide European Australian RLS (PEARLS) study. Group 2 (n=100) represented an outpatient RLS population investigated in a Sleep Disorders Center. Additionally, Group 1 was also evaluated after a 6 week double-blind treatment period, where 47 patients received pergolide and 53 patients placebo. RESULTS: In unmedicated patients, IRLS scores correlated with the PLMS-arousal index (r=0.22, p=0.033) but not with the PLMS index in Group 1 while no correlation was found in Group 2. The change of the IRLS score under treatment in Group 1 correlated significantly both with the change of the PLMS index (r=0.42, p<0.001) and the change of the PLMS-arousal index (r=0.38, p<0.001). CONCLUSIONS: The IRLS adequately reflects treatment changes of PLMS indices. In unmedicated patients, the IRLS correlates with PLMS indices probably only in selected RLS populations with predefined PSG criteria and high PLM activity. SIGNIFICANCE: The IRLS is an appropriate subjective rating scale for measuring treatment effects in RLS. 相似文献
47.
Eberhard Unsöld Christian Ell Dieter Jocham Ronald Sroka Susanne Stocker 《Lasers in medical science》1990,5(3):309-316
Eight commercially available HPD-photosensitizers intended for photodynamic therapy were tested in a murine tumour model with regard to their therapeutic efficacy. The regrowth delay of the fibrosarcoma SSK-2 on the mouse C3H, Neuherberg-line, was determined 3, 24, 48 and 72 h after injection of the drugs (dose: 9 mg kg–1 body weight). The corresponding pharmacodynamics, as measured by regrowth delay, were approximated by an exponential function and the characterizing coefficients derived. These coefficients served to quantify the photodynamic properties of the drugs.The pharmacodynamics of five substances were compared with those obtained fluorometrically. The latter showed shorter decay constants than the therapy-correlated substances which indicates different metabolic behaviour of the therapeutic and diagnostically useful fluorescent components of haematoporphyrin-derived photosensitizers. 相似文献
48.
49.
G. Bruce Pike Gary H. Glover Bob S. Hu Dieter R. Enzmann 《Journal of magnetic resonance imaging : JMRI》1993,3(3):531-539
Cross relaxation between macromolecular protons and water protons is known to be important in biologic tissue. In magnetic resonance (MR) imaging sequences, selective saturation of the characteristically short T2 macromolecular proton pool can produce contrast called magnetization transfer contrast, based on the cross-relaxation process. Selective saturation can be achieved with continuous wave irradiation several kilohertz off resonance or short, intense 0° pulses on resonance. The authors analyze 0° binomial pulses for T2 selective saturation, present design guidelines, and demonstrate the use of these pulses in spin-echo imaging sequences in healthy volunteers and patients. Using the phenomenologic Bloch equations modified for two-site exchange, the authors derive the analytic expressions for water proton relaxation under periodic pulsed saturation of the macromolecular protons. This relaxation is shown to be monoexpo-nential, with a rate constant dependent on the saturation pulse repetition rate and the individual and cross-relaxation rates. 相似文献
50.
Soyka D 《Schmerz (Berlin, Germany)》1988,2(2):94-95
Ohne Zusammenfassung 相似文献