全文获取类型
收费全文 | 152430篇 |
免费 | 9019篇 |
国内免费 | 1402篇 |
专业分类
耳鼻咽喉 | 2440篇 |
儿科学 | 2392篇 |
妇产科学 | 2535篇 |
基础医学 | 23774篇 |
口腔科学 | 3520篇 |
临床医学 | 14092篇 |
内科学 | 28283篇 |
皮肤病学 | 4586篇 |
神经病学 | 12101篇 |
特种医学 | 8447篇 |
外科学 | 20260篇 |
综合类 | 1043篇 |
现状与发展 | 3篇 |
一般理论 | 42篇 |
预防医学 | 7893篇 |
眼科学 | 3968篇 |
药学 | 13595篇 |
中国医学 | 1643篇 |
肿瘤学 | 12234篇 |
出版年
2023年 | 1087篇 |
2022年 | 3154篇 |
2021年 | 5169篇 |
2020年 | 2508篇 |
2019年 | 3590篇 |
2018年 | 4412篇 |
2017年 | 3509篇 |
2016年 | 4537篇 |
2015年 | 6237篇 |
2014年 | 7435篇 |
2013年 | 8752篇 |
2012年 | 13052篇 |
2011年 | 12606篇 |
2010年 | 7253篇 |
2009年 | 6287篇 |
2008年 | 8988篇 |
2007年 | 8547篇 |
2006年 | 7716篇 |
2005年 | 7221篇 |
2004年 | 6263篇 |
2003年 | 5611篇 |
2002年 | 4899篇 |
2001年 | 3765篇 |
2000年 | 3445篇 |
1999年 | 2745篇 |
1998年 | 1125篇 |
1997年 | 882篇 |
1996年 | 716篇 |
1995年 | 614篇 |
1994年 | 535篇 |
1993年 | 432篇 |
1992年 | 1042篇 |
1991年 | 923篇 |
1990年 | 899篇 |
1989年 | 811篇 |
1988年 | 705篇 |
1987年 | 667篇 |
1986年 | 509篇 |
1985年 | 530篇 |
1984年 | 400篇 |
1983年 | 303篇 |
1982年 | 214篇 |
1981年 | 239篇 |
1980年 | 196篇 |
1979年 | 342篇 |
1978年 | 243篇 |
1977年 | 184篇 |
1976年 | 176篇 |
1975年 | 179篇 |
1974年 | 192篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Jong Il Kim Takeshi Tsujino Yoshio Fujioka Komei Saito Mitsuhiro Yokoyama 《Hypertension research》2003,26(4):307-313
We examined cellular membrane fatty acid composition and insulin sensitivity in patients with mild essential hypertension and hyperlipidemia, and investigated whether bezafibrate, a lipid-lowering drug, could improve elevated blood pressure and insulin sensitivity in these subjects by ameliorating cellular membrane fatty acid composition. Twenty-seven subjects were recruited. Twelve men with mild essential hypertension [systolic blood pressure (SBP) between 140 mmHg and 160 mmHg] and hypertriglyceridemia (plasma triglyceride concentration over 150 mg/dl) were designated the HL group. Fifteen men with mild essential hypertension and normotriglyceridemia (plasma triglyceride concentration below 150 mg/dl) were designated the NL group. Subjects in the HL group were given bezafibrate 400 mg/dl and those in the NL group were given placebo for 3 months. Bezafibrate significantly reduced SBP (140 +/- 2.6 to 131.8 +/- 2.6 mmHg, mean +/- SEM), diastolic blood pressure (DBP) (87.8 +/- 2.0 to 82.8 +/- 2.6 mmHg), fasting plasma triglyceride concentration (225.5 +/- 23.5 to 102.9 +/- 10.9 mg/dl), fasting plasma insulin concentration (9.6 +/- 0.8 to 7.1 +/- 0.8 microU/ml), and homeostasis model assessment scores (HOMA-R, 2.4 +/- 0.2 to 1.7 +/- 0.2), and significantly improved the insulin sensitivity index (56.0 +/- 3.0 to 70.7 +/- 4.8 mg x l2/mmol x mU x min) in the HL group. Regarding erythrocyte membrane fatty acid composition, bezafibrate reduced the percentages of saturated fatty acids (SFA) and increased the percentage of polyunsaturated fatty acids (PUFA). Plasma triglyceride concentrations were positively correlated with HOMA-R (r = 0.50, p < 0.01) and SFA (r = 0.39, p < 0.05), and negatively correlated with PUFA (r = -0.45, p < 0.05) before administration of placebo or bezafibrate. In conclusion, an improvement of hyperlipidemia by bezafibrate may be attributed to reduction of blood pressure and amelioration of insulin sensitivity. Abnormalities in membrane lipid composition may play an important role in these metabolic disorders. 相似文献
72.
Kim Mudd Mary Elizabeth Bollinger Van Doren Hsu Michele Donithan Arlene Butz 《The Journal of asthma》2006,43(8):597-600
Background. Medication adherence impacts healthcare utilization. Pharmacy records are useful to establish fill patterns. Objective. Use pharmacy records to establish medication patterns fill patterns for comparison to healthcare utilization. Methods. Pharmacy records of 175 children with persistent asthma were collected and compared to healthcare utilization. Results. Majority of subjects had significant healthcare utilization, low numbers of rescue medications, and poor controller medication fill rates. Those with more rescue medications had more healthcare utilization and more controller medications. Conclusions. Pharmacy fill patterns demonstrate few rescue and/or controller medication fills. Those with more rescue medications reported increased healthcare utilization despite controller medications. 相似文献
73.
74.
Jin-Seon Song Francis K Mante William J Romanow Syngcuk Kim 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2006,102(6):809-815
OBJECTIVE: To evaluate the chemical composition and crystalline structures of Portland cement, gray ProRoot MTA (gray MTA), white ProRoot MTA (white MTA), and gray MTA-Angelus. STUDY DESIGN: X-ray diffraction analysis was used to identify and characterize crystalline phases, and energy dispersive x-ray spectrometer was used to determine the chemical composition of the test materials. Both powder form and set form were examined. RESULTS: The crystalline structure and chemical composition of gray and white MTA were similar except for the presence of iron in gray MTA. Both were composed mainly of bismuth oxide and calcium silicate oxide. Portland cement was composed mainly of calcium silicate oxide and did not contain bismuth oxide. Gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA. There were no noticeable differences in the chemical composition and crystalline structures between the powder and set forms of any of the material tested. CONCLUSION: Portland cement differed from the MTA by the absence of bismuth ions and presence of potassium ions. Gray MTA contained a significant amount of iron when compared with white MTA. In addition, gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA. 相似文献
75.
Airway hyperresponsiveness (AHR) is a characteristic feature of asthma, but is also frequently demonstrated by children and adults with chronic obstructive lung diseases. AHR is usually measured by bronchial challenges using direct or indirect stimuli. The aim of this study was to compare these two types of bronchial challenge in children with post-infectious bronchiolitis obliterans (BO). Methacholine and adenosine 5'-monophosphate (AMP) challenges were used as tools for the evaluation of AHR to direct and indirect stimuli, respectively, in children with post-infectious BO (n = 28). These results were compared with those of asthmatic (n = 30) and control children (n = 25). Altogether, twenty-two patients (78.6%) with post-infectious BO were hyperreactive to methacholine with a provocative concentration causing a 20% fall in forced expiratory volume in one second (PC20) of <16 mg x mL(-1), but only six (21.4%) were hyperreactive to AMP with a PC20 of <200 mg x mL(-1). All patients with asthma responded positively to methacholine, and most (28, 93.3%) also responded positively to AMP. The majority of controls were insensitive to both challenges. Airway hyperresponsiveness to methacholine is a frequent, but by no means universal, finding in children with post-infectious bronchiolitis obliterans, but is usually not accompanied by airway hyperresponsiveness to adenosine 5'-monophosphate. This finding suggests that airway hyperresponsiveness in patients with post-infectious bronchiolitis obliterans has characteristics that differ from those of asthmatic subjects. 相似文献
76.
77.
Wolfgang G Rehwald Michael Salerno Enn-Ling Chen Burkhard Sievers Raymond J Kim Robert M Judd 《Magnetic resonance in medicine》2007,58(1):82-91
To extend the signal longevity of magnetically excited spins in flowing fluids while in a state of global coherent free precession (GCFP), a refocusing radiofrequency (RF) pulse and bipolar gradient waveforms were combined with the GCFP sequence. The data demonstrate that RF refocusing in the presence of flowing blood is possible, but the improvement in signal amplitude depends on the static magnetic field homogeneity along the direction of motion and the displacement of the spins between the excitation and the RF refocusing pulse, as well as displacement during subsequent RF refocusing pulses. The least amount of phase dispersion and thus the longest lasting signal is obtained with the shortest echo spacing where only one line of data is recorded between two RF refocusing pulses. This approach was successfully used in a phantom and in vivo to image fast and slow blood flow. Depending on the experimental conditions, signal persistence is improved significantly compared to playing the same sequence without RF refocusing, but the improvement is limited by the product of blood flow velocity and the time between RF refocusing pulses. 相似文献
78.
79.
Huey-Juan Lin Poh-Shiow Yeh Tsung-Chia Tsai Tain-Junn Cheng Dershin Ke Kao-Chang Lin Jih-Gong Ho Chia-Yu Chang 《Journal of clinical neuroscience》2007,14(1):17-21
Using a prospective hospital-based registry, 146 patients with transient ischaemic attack (TIA) were compared with 376 patients with minor first-ever ischaemic stroke with respect to the 3-month risk of subsequent vascular events, in order to clarify the distinctions between the disease entities. All patients were enrolled within 48 h of onset. The risk factor distribution for the two groups was comparable, except that the TIA patients had more previous TIAs. Large artery atherosclerosis (34%) and small vessel occlusion (32%) were the main aetiologies in the TIA group, whereas small vessel occlusion (49%) was the major cause in the stroke group. The 3-month risk of combined endpoints of stroke, myocardial infarction, and vascular death for TIA patients was higher than that for the minor stroke group (15.1% vs. 3.2%; hazard ratio 4.6, 95% confidence interval 2.3-9.3 in multivariate analysis). Large artery atherosclerosis and male sex were the other significant predictors. TIA may demand more urgent management than minor stroke. The fact that aetiology is a predictor, highlights the need for rapid diagnostic tests to establish pathogenesis. 相似文献
80.
A case of spontaneous thrombosis and infarction leading to death as complications of a cerebral venous malformation in a 13-yearold boy is reported. This is the first published report of this type of complication occurring in a case of venous angioma. While the biologic behavior of cerebral venous malformations has suggested that they are benign in nature, and the results of surgical management have encouraged a conservative approach, the present case illustrates a potential complication and argues against the assumption that these malformations are completely benign in nature. 相似文献