全文获取类型
收费全文 | 37177篇 |
免费 | 2136篇 |
国内免费 | 201篇 |
专业分类
耳鼻咽喉 | 425篇 |
儿科学 | 1152篇 |
妇产科学 | 1012篇 |
基础医学 | 3696篇 |
口腔科学 | 1220篇 |
临床医学 | 3255篇 |
内科学 | 8009篇 |
皮肤病学 | 670篇 |
神经病学 | 2212篇 |
特种医学 | 1314篇 |
外国民族医学 | 4篇 |
外科学 | 6784篇 |
综合类 | 861篇 |
现状与发展 | 3篇 |
一般理论 | 27篇 |
预防医学 | 2513篇 |
眼科学 | 1356篇 |
药学 | 2864篇 |
1篇 | |
中国医学 | 266篇 |
肿瘤学 | 1870篇 |
出版年
2024年 | 39篇 |
2023年 | 414篇 |
2022年 | 1054篇 |
2021年 | 1645篇 |
2020年 | 984篇 |
2019年 | 1257篇 |
2018年 | 1573篇 |
2017年 | 1139篇 |
2016年 | 1237篇 |
2015年 | 1332篇 |
2014年 | 1685篇 |
2013年 | 2053篇 |
2012年 | 3109篇 |
2011年 | 3000篇 |
2010年 | 1692篇 |
2009年 | 1464篇 |
2008年 | 2226篇 |
2007年 | 2295篇 |
2006年 | 2024篇 |
2005年 | 1789篇 |
2004年 | 1625篇 |
2003年 | 1349篇 |
2002年 | 1177篇 |
2001年 | 363篇 |
2000年 | 306篇 |
1999年 | 280篇 |
1998年 | 197篇 |
1997年 | 132篇 |
1996年 | 141篇 |
1995年 | 107篇 |
1994年 | 95篇 |
1993年 | 77篇 |
1992年 | 147篇 |
1991年 | 160篇 |
1990年 | 128篇 |
1989年 | 125篇 |
1988年 | 104篇 |
1987年 | 100篇 |
1986年 | 89篇 |
1985年 | 117篇 |
1984年 | 77篇 |
1983年 | 54篇 |
1982年 | 56篇 |
1981年 | 56篇 |
1980年 | 42篇 |
1979年 | 52篇 |
1978年 | 41篇 |
1975年 | 35篇 |
1974年 | 36篇 |
1973年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Sedigheh Sadat Tavafian Ahmadreza Jamshidi Kazem Mohammad Ali Montazeri 《BMC musculoskeletal disorders》2007,8(1):21
Background
Different interventions can reduce the burden of the chronic low back pain. One example is the use of a 'Back School Programme'. This is a brief therapy that uses a health education method to empower participants through a procedure of assessment, education and skill development. This study aimed to evaluate to what extent the programme could improve quality of life in those who suffer from the condition. 相似文献32.
Ayce Unverdi Eldeniz Ali Erdemir Firuze Kurtoglu Timur Esener 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,103(3):e86-e91
OBJECTIVE: This is an in vitro assessment of pH level and calcium ion release exhibited by 3 calcium hydroxide-based root canal sealers-Sealapex, Apexit, and Acroseal. STUDY DESIGN: The materials were prepared according to the manufacturers' instructions and placed in 1 cm long and 4 mm diameter tubes. The tubes were then immersed in a glass flask containing 10 mL bidistilled water (n = 15), which was sealed and stored at 37 degrees C before the materials had set. The control group contained bidistilled water with empty tubes (n = 12). At predetermined time intervals (24 h, 96 h, and 7, 15, and 28 days) the pH of the bidistilled water was tested with a pH meter and for released calcium by using spectrophotometry. The data were statistically analyzed using 1-way analysis of variance for the comparison of the materials at each time point. If the difference was significant, individual comparisons were performed by Tukey multiple comparisons test (alpha = .05). RESULTS: Sealapex produced higher pH and released significantly higher calcium amounts than the other 2 sealers at all periods (P < .05). Apexit showed higher calcium release than Acroseal at the end of 15 days (P < .05). There was no significant difference in the pH between Apexit and Acroseal (P > .05). CONCLUSION: The new Acroseal sealer presented the least calcium ion release and pH than Sealapex and less calcium ion release than Apexit sealer. 相似文献
33.
Aiman A Ali 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,103(3):e55-e59
BACKGROUND: Because the clinicopathologic effects of takhzeen al-qat are similar to those induced by smoking, the aim of this paper was to study the oral effect of 3 bad oral habits: takhzeen al-qat and cigarette and water-pipe smoking. STUDY DESIGN: This study was done on 33 Yemeni chronic qat users grouped as heavy cigarette smokers (GI), nonsmokers (GII) and water-pipe smokers (GIII). In all cases (n = 33) 2 biopsies were taken (n = 66), one from the buccal mucosa at the chewing side and the other from a similar mucosa at the contralateral (nonexposed) side. Biopsies were prepared for routine H&E staining. RESULTS: Acanthosis appeared in 88% and 0%, abnormal rete ridges in 70% and 3%, hyperparakeratosis in 67% and 0%, and epithelial dysplasia in 30% and 0% of the chewing and nonchewing sides, respectively, in the 3 groups. Epithelial dysplasia appeared in 41% of GI and GIII (smokers) but in only 9% of GII (nonsmokers). CONCLUSIONS: Takhzeen al-qat causes distinct histopathologic changes in the oral mucosa at the side of chewing, such as acanthosis, abnormal rete ridges, and hyperparakeratosis. The association between takhzeen al-qat and cigarette or water-pipe smoking may increase the risk of epithelial dysplasia. 相似文献
34.
Zhiqiang Li Arthur F Gmitro Ali Bilgin Maria I Altbach 《Magnetic resonance in medicine》2007,57(6):1047-1057
Three-point Dixon techniques achieve good lipid-water separation by estimating the phase due to field inhomogeneities. Recently it was demonstrated that the combination of an iterative algorithm (iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL)) with a fast spin-echo (FSE) three-point Dixon method yielded robust lipid-water decomposition. As an alternative to FSE, the gradient- and spin-echo (GRASE) technique has been developed for efficient data collection. In this work we present a method for lipid-water separation by combining IDEAL with the GRASE technique. An approach to correct for errors in the lipid-water decomposition caused by phase distortions due to the switching of the readout gradient polarities inherent to GRASE is presented. The IDEAL-GRASE technique is demonstrated in phantoms and in vivo for various applications, including pelvic, musculoskeletal, and (breath-hold) cardiac imaging. 相似文献
35.
36.
37.
Ali S. Ziaee Nadia Khatibzadeh Alireza Rahimnia Ahmad S. Mousavi Shaban Mehrvarz 《European journal of orthopaedic surgery & traumatology : orthopedie traumatologie》2005,15(4):270-274
The aim of this study is to identify the effect of time and pressure of tourniquet in blood pressure and pulse rate immediately after the releasing of tourniquet in the upper and lower extremity of the orthopedic surgeries. This retrospective study examined 206 consecutive patients. Comparisons of the systolic and diastolic pressure and heart rate were made before the induction of anesthesia and tourniquet inflation, and immediately after the deflation. In general, there was no significant difference in hemodynamic changes between the upper- and lower-limb with regard to the type of anesthesia. There was no significant correlation between systolic blood pressure and tourniquet pressure, while by increasing the tourniquet time significantly, the systolic blood pressure decreases immediately after the deflation. Interestingly, the considerable increase in age paralleled with a significant decrease in the systolic blood pressure. The effect of tourniquet time is more than the age. There was no significant correlation between the tourniquet pressure and tourniquet time with diastolic blood pressure. Simply the increase in age significantly paralleled with the mild decrease in diastolic blood pressure Orthopedic surgeons are recommended not to rely on the benefits of tourniquet to raise blood pressure due to hypotensive conditions after the deflation especially in the old. 相似文献
38.
Agents ameliorating or augmenting experimental gentamicin nephrotoxicity: some recent research. 总被引:7,自引:0,他引:7
B H Ali 《Food and chemical toxicology》2003,41(11):1447-1452
Despite its nephrotoxic potential, the aminoglycoside antibiotic gentamicin (GM) is still considered to be an important agent against life-threatening infections. The goal of reducing or protecting against its nephrotoxicity has attracted much effort and attention during the last decade. This article reviews some of the literature published during the last decade on the effects of agents that ameliorate or augment GM nephrotoxicity. Notable among the ameliorating agents are antioxidant agents. These include different classes of compounds that include beta blockers (e.g. carvedilol), superoxide dismutase mimetic agents (e.g. M40403), hormones (e.g. melatonin), iron chelators (e.g. deferrioxamine), vitamins (vitamin C and E) and medicinal plants (e.g. garlic). Other ameliorating agents include antibiotics (e.g. ceftriaxone), antiplatelet drugs (e.g. trapidil) and Ca++ agents that may augment GM nephrotoxicity include cyclosporin and the Ca++-channel blocker verapamil. 相似文献
39.
Gastrointestinal transit in mice treated with various extracts of date (Phoenix dactylifera L.). 总被引:1,自引:0,他引:1
Dates are commonly consumed, especially in the Middle East, but their effect on gastrointestinal transit (GIT) has not been quantified. The effect of water and ethanol extracts from date flesh and date pits on the GIT in mice was studied. Fasted unanaesthetized male mice received by gavage either the vehicle (0.02 m/kg), or the extracts at doses of 0.01, 0.02 or 0.04 ml/kg. Two separate groups received either clonidine (1 mg/kg) or yohimbine (2 mg/kg). Two hours later, all animals were given a test meal containing charcoal and gum arabic in water. Thirty min thereafter, they were killed and the distance the charcoal column had traveled along the small intestine was measured. Compared with the control, the animals that received the ethanol and water extracts of both date flesh and pits emptied, in a dose-dependent manner, more of their gastrointestinal content. The increase in the GIT ranged from 4 to 22%. However, water extract from dialyzed date flesh induced a dose-dependent decrease in GIT that ranged from 4 to 24%. Clonidine exerted a significant decrease (68%), and yohimbine a significant increase (30%) in the GIT. Depending on the method of extraction, the date extracts may exert an increase or a decrease in GIT. 相似文献
40.
Flow-directed pulmonary artery catheters provide important information regarding intravascular volume status, cardiac function and vascular resistance. We describe an unusual complication of pulmonary artery catheterization in which a knot formed at the distal end was torn away from the catheter body and migrated from its original position in the right subclavian vein to a distal branch of the right pulmonary artery. Careful attention to insertion and withdrawal techniques could prevent this potentially serious complication. 相似文献