全文获取类型
收费全文 | 38184篇 |
免费 | 2177篇 |
国内免费 | 209篇 |
专业分类
耳鼻咽喉 | 481篇 |
儿科学 | 1173篇 |
妇产科学 | 1041篇 |
基础医学 | 3812篇 |
口腔科学 | 1256篇 |
临床医学 | 3394篇 |
内科学 | 8193篇 |
皮肤病学 | 697篇 |
神经病学 | 2260篇 |
特种医学 | 1365篇 |
外国民族医学 | 4篇 |
外科学 | 6912篇 |
综合类 | 877篇 |
现状与发展 | 3篇 |
一般理论 | 28篇 |
预防医学 | 2554篇 |
眼科学 | 1367篇 |
药学 | 2959篇 |
1篇 | |
中国医学 | 279篇 |
肿瘤学 | 1914篇 |
出版年
2024年 | 42篇 |
2023年 | 433篇 |
2022年 | 1092篇 |
2021年 | 1712篇 |
2020年 | 1026篇 |
2019年 | 1296篇 |
2018年 | 1615篇 |
2017年 | 1168篇 |
2016年 | 1259篇 |
2015年 | 1344篇 |
2014年 | 1713篇 |
2013年 | 2105篇 |
2012年 | 3161篇 |
2011年 | 3061篇 |
2010年 | 1727篇 |
2009年 | 1494篇 |
2008年 | 2269篇 |
2007年 | 2352篇 |
2006年 | 2062篇 |
2005年 | 1823篇 |
2004年 | 1659篇 |
2003年 | 1385篇 |
2002年 | 1210篇 |
2001年 | 388篇 |
2000年 | 329篇 |
1999年 | 298篇 |
1998年 | 204篇 |
1997年 | 139篇 |
1996年 | 147篇 |
1995年 | 114篇 |
1994年 | 97篇 |
1993年 | 79篇 |
1992年 | 163篇 |
1991年 | 170篇 |
1990年 | 136篇 |
1989年 | 132篇 |
1988年 | 114篇 |
1987年 | 102篇 |
1986年 | 96篇 |
1985年 | 119篇 |
1984年 | 81篇 |
1983年 | 53篇 |
1982年 | 59篇 |
1981年 | 57篇 |
1980年 | 43篇 |
1979年 | 56篇 |
1978年 | 43篇 |
1975年 | 39篇 |
1974年 | 40篇 |
1973年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
G Talaska M Schamer J R Bailey S F Ali A C Scallet W Slikker M G Paule 《Toxicology letters》1992,63(3):321-332
Rhesus monkeys exposed to marijuana smoke either 7 or 2 days/weeks (HI and LO groups, respectively), or ethanol-extracted marijuana smoke for 7 days/week (EM) or sham treatment (SH) for 1 year were sacrificed 7 months following the last exposure. Pulmonary levels of carcinogen-DNA adducts were determined. Although mean or median adduct levels were not statistically different, 15 of 22 adduct measures were highest in the EM group and lowest 12 of 22 times in the SH group. The levels of aromatic carcinogen-DNA adducts seem no higher in the lungs of animals exposed to marijuana smoke than in untreated animals. Ethanol-extracted marijuana may have effects greater than marijuana itself. 相似文献
82.
Ali Ahmed Mahmud Ali Christina M Lefante M Syadul Islam Mullick F Cleveland Kinney 《The American journal of geriatric psychiatry》2006,14(10):867-875
OBJECTIVE: Heart failure (HF) and depression are both common in older adults, and the presence of depression is known to worsen HF outcomes. For community-dwelling older adults, admission to a nursing home (NH) is associated with loss of independent living and poor outcomes. The objective of this study was to examine the effect of depression on NH admission for older adults with HF. METHODS: Using the 2001-2003 National Hospital Discharge Survey datasets, the authors identified all community-dwelling older adults who were discharged alive with a primary discharge diagnosis of HF. The authors then identified those with a secondary diagnosis of depression. Using a multivariable logistic regression model, the authors then determined probability or propensity to have depression for each patient. The authors used propensity scores for depression to match all 680 depressed patients with 2,040 nondepressed patients. Finally, the authors estimated the association between depression and NH admission using bivariate and multivariable logistic regression analyses. RESULTS: Patients had a mean (+/- standard deviation) age of 79 (+/- 8) years, 72% were women, and 9% were blacks. Compared with 17% nondepressed patients, 25% depressed patients were discharged to a NH. Depression was associated with 50% increased risk of NH admission (unadjusted relative risk [RR]: 1.50; 95% confidence interval [CI]: 1.28-1.74). The association became somewhat stronger after multivariable adjustment for various demographic and care covariates (adjusted RR: 1.60; 95% CI: 1.35-1.68). CONCLUSION: In ambulatory older adults hospitalized with HF, a secondary diagnosis of depression was associated with a significant increased risk of NH admission. 相似文献
83.
Shafqat Hasan Ali N A Jilaihawi Dhruva Prakash 《European journal of cardio-thoracic surgery》2005,28(1):7-10
OBJECTIVE: Iatrogenic Oesophageal perforations are a dreaded complication and there is no consensus as to their best management. The aim of our study was to assess the results of conservative management in these cases. METHODS: Twenty-six patients with iatrogenic perforations of the oesophagus treated over a 10-year period were reviewed retrospectively. They were managed conservatively by keeping them nil by mouth on intravenous fluids and intravenous antibiotics. Out of these 26, nine were patients of carcinoma of the oesophagus while the remaining 17 had benign pathologies. Twenty-two were diagnosed within 6h, while the remaining four were diagnosed over 24h after perforation. Twenty-three of the 26 were caused by oesophageal dilatations. RESULTS: Twenty-two (84.6%) of the 26 survived on this regimen. Out of the four that died, two had advanced carcinomas and died of chest complications, one died of a myocardial infarction and the fourth was an old debilitated man who died of renal failure. All four who died had extension of the leak into the pleural cavity. Early diagnosis and treatment is of critical importance and is only possible by maintaining a high index of suspicion. CONCLUSIONS: Conservative management when applied to cases of iatrogenic oesophageal perforations gives results comparable to or better that those reported in series where early surgical intervention was practised. Extension of the leak into the pleura carries a worse prognosis. 相似文献
84.
85.
Ali Ihya Karaman Omür Polat Tamer Büyükyilmaz 《American journal of orthodontics and dentofacial orthopedics》2003,124(3):327-330
Retention is a major part of orthodontic treatment, not an optional secondary protocol. In recent years, studies investigating dentofacial changes during and after the growth period have led most clinicians to use fixed retention appliances after treatment. Fixed retainers can be attached to the teeth directly or indirectly. We present a practical, indirect method for bonding fixed retainers, using Sondhi Rapid-set Indirect Bonding Adhesive (3M Unitek, Monrovia, Calif). 相似文献
86.
Ali Gürbüz Bilgin Emrecan Levent Yilik Ibrahim Ozs?yler Mert Kestelli Cengiz Ozbek Nagihan Karahan 《European journal of cardio-thoracic surgery》2006,29(2):186-189
OBJECTIVE: The purpose of this study was to evaluate whether intracoronary shunt usage reduced the myocardial damage on the basis of the cardiac markers when compared with the shuntless anastomosis in off-pump coronary artery bypass grafting (OPCABG) surgery of isolated left anterior descending artery lesions. METHODS: Forty patients who had stable angina with isolated left anterior descending (LAD) coronary artery lesion undergoing OPCABG surgery were randomized into two groups. Shunt group consisted of 20 patients who had OPCABG using intracoronary shunt, whereas the shuntless group consisted of 20 patients who underwent OPCABG without using intracoronary shunt. Cardiac troponin I, CK, and CK-MB before and 24h after the surgery were assessed in the groups. RESULTS: There were no deaths in the study. The two groups were similar with respect to sex and age. Duration of LIMA-LAD anastomosis was significantly higher in the shunt group (p=0.01). There was no significant difference between the groups concerning the preoperative and postoperative CK and CK-MB levels. The preoperative troponin I levels of the groups were not different (p=0.238; NS), whereas postoperative levels of this marker was significantly higher in the shuntless group (p=0.003). CONCLUSION: Intracoronary shunt reduced the postoperative troponin I levels significantly, so it may be indicated in the patients who are thought to be susceptible to transient ischemia. 相似文献
87.
Abdul Rahman D El Kinge Rami A Mahfouz Ali I Shamseddine Ali T Taher 《Blood coagulation & fibrinolysis》2007,18(6):577-579
Recombinant activated factor VII has been Food and Drug Administration approved to treat hemorrhages in hemophiliac patients with inhibitors and in acquired hemophilia patients. Recombinant activated factor VII use has also been considered for the management of uncontrolled bleeding in a number of congenital and acquired hemostatic abnormalities. The myeloproliferative disorders are a group of clonal hematologic diseases where, frequently, abnormal platelet function is considered a hallmark. This is the first case report addressing the clinical benefit of off-label use of recombinant activated factor VII in an attempt to control intractable bleeding in a patient with a myeloproliferative disorder after splenectomy. 相似文献
88.
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89.
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
90.
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