全文获取类型
收费全文 | 253326篇 |
免费 | 16500篇 |
国内免费 | 1018篇 |
专业分类
耳鼻咽喉 | 2680篇 |
儿科学 | 6490篇 |
妇产科学 | 4863篇 |
基础医学 | 31564篇 |
口腔科学 | 4739篇 |
临床医学 | 26257篇 |
内科学 | 52744篇 |
皮肤病学 | 3417篇 |
神经病学 | 25458篇 |
特种医学 | 10599篇 |
外国民族医学 | 13篇 |
外科学 | 39349篇 |
综合类 | 3082篇 |
现状与发展 | 1篇 |
一般理论 | 200篇 |
预防医学 | 18542篇 |
眼科学 | 5951篇 |
药学 | 16896篇 |
1篇 | |
中国医学 | 330篇 |
肿瘤学 | 17668篇 |
出版年
2023年 | 1413篇 |
2022年 | 2303篇 |
2021年 | 5564篇 |
2020年 | 3209篇 |
2019年 | 5279篇 |
2018年 | 6357篇 |
2017年 | 4672篇 |
2016年 | 5113篇 |
2015年 | 6022篇 |
2014年 | 8706篇 |
2013年 | 11822篇 |
2012年 | 18142篇 |
2011年 | 18873篇 |
2010年 | 10556篇 |
2009年 | 9750篇 |
2008年 | 16666篇 |
2007年 | 17502篇 |
2006年 | 16987篇 |
2005年 | 16832篇 |
2004年 | 15851篇 |
2003年 | 14505篇 |
2002年 | 13929篇 |
2001年 | 2538篇 |
2000年 | 1991篇 |
1999年 | 2499篇 |
1998年 | 3029篇 |
1997年 | 2389篇 |
1996年 | 2120篇 |
1995年 | 1948篇 |
1994年 | 1702篇 |
1993年 | 1666篇 |
1992年 | 1363篇 |
1991年 | 1300篇 |
1990年 | 1200篇 |
1989年 | 1113篇 |
1988年 | 1034篇 |
1987年 | 958篇 |
1986年 | 976篇 |
1985年 | 975篇 |
1984年 | 1138篇 |
1983年 | 977篇 |
1982年 | 1158篇 |
1981年 | 1082篇 |
1980年 | 944篇 |
1979年 | 699篇 |
1978年 | 666篇 |
1977年 | 575篇 |
1976年 | 540篇 |
1975年 | 457篇 |
1974年 | 473篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Emir Q. Haxhija Prof. Dr. Johannes M. Mayr Wolfgang Grechenig Michael E. Höllwarth 《Operative Orthopadie und Traumatologie》2006,18(2):120-134
OBJECTIVE: Surgical reduction and retention of apophyseal avulsion injuries at the medial epicondyle to prevent joint instability, lasting malalignment, or pseudarthrosis. INDICATIONS: Absolute: intraarticular apophyseal dislocation of the medial epicondyle, complete lesion of the ulnar nerve. Relative: dislocation of the apophysis (> 4 mm) in children > 5 years of age; the need for intervention increases in children as the degree of dislocation, age, and athletic activity increase. CONTRAINDICATIONS: Dislocation of the medial epicondyle (< or = 4 mm) in children < 5 years of age, provided the fragment location is not intraarticular. SURGICAL TECHNIQUE: Open reduction of the apophysis through a medial approach. Identification of the ulnar nerve. In young children or with small fragments fixation with Kirschner wire. Screw fixation in older children or for larger fragments. POSTOPERATIVE MANAGEMENT: Long upper-arm plaster cast until wound healing is achieved. Subsequently, upper-arm plaster cast for 3 weeks. Removal of Kirschner wires after 4-6 weeks, screw removal after 8-12 weeks. Physiotherapy only if marked reduction of elbow mobility is found 6 weeks after cast removal. RESULTS: From January 1, 1994 to December 31, 2003, 25 children with an average age of 12 years suffering from medial epicondylar avulsion fractures were operated on using open reduction and Kirschner wire fixation. An average of 3 years after the injury 14 of these children underwent follow-up examination using a procedure that took subjective, clinical and radiologic parameters into account. Two children showed a slight reduction in overall strength of the injured extremity when compared with the contralateral extremity. One child had a flexion deficit of 10 degrees, all other children showed movement limitations of < or = 5 degrees compared to the contralateral extremity. In all the cases available to follow-up, there was a slight increase in valgus alignment of the elbow joint compared with the uninjured side (3 degrees on average). All fractures consolidated within 6 weeks. 相似文献
22.
A Sharma H L Goh N Asokananthan A Bakker G A Stewart H W Mitchell 《The European respiratory journal》2006,27(1):20-28
Mucosal trypsin, a protease-activated receptor (PAR) stimulant, may have an endogenous bronchoprotective role on airway smooth muscle. To test this possibility the effects of lumenal trypsin on airway tone in segments of pig bronchus were tested. Bronchial segments from pigs were mounted in an organ chamber containing Kreb's solution. Contractions were assessed from isovolumetric lumen pressure induced by acetylcholine (ACh) or carbachol added to the adventitia. Trypsin, added to the airway lumen (300 microg x mL(-1)), had no immediate effect on smooth muscle tone but suppressed ACh-induced contractions after 60 min, for at least 3 h. Synthetic activating peptides (AP) for PAR1, PAR2 or PAR3 were without effect, but PAR4 AP caused rapid, weak suppression of contractions. Lumenal thrombin was without effect and did not prevent the effects of trypsin. Effects of trypsin were reduced by N(omega)-nitro-L-arginine methyl ester but not indomethacin. Trypsin, thrombin and PAR4 AP released prostaglandin E2. Adventitially, trypsin, thrombin and PAR4 AP (but not PAR2 AP) relaxed carbachol-toned airways after <3 min. The findings of this study show that trypsin causes delayed and persistent bronchoprotection by interacting with airway cells accessible from the lumen. The signalling mechanism may involve nitric oxide synthase but not prostanoids or protease-activated receptors. 相似文献
23.
Michael Givel 《Int J Health Serv》2006,36(1):137-155
From the early 1980s to the present, neoliberal doctrine has called for government policies of privatization, funding cutbacks, and deregulation of public health and other domestic social programs in the belief that the market rather than the public sector can best organize and distribute crucial societal services. Proponents of a neoliberal and deregulatory mixed approach of command and control and self-regulation argue this approach provides the most adequate means to conduct regulation in the legalistic and adversarial U.S. regulatory process. In April 1994, the Occupational Safety and Health Administration issued a proposed rule to eliminate tobacco smoking in most workplace rooms, arguing secondhand tobacco smoke annually killed up to 13,700 nonsmokers. The tobacco industry purposely delayed public hearing procedures (later halted altogether by Congress and the president) primarily to advance unhindered private property rights and profits rather than submitting to a public command-and-control regulatory framework to reduce deaths due to secondhand tobacco smoke. 相似文献
24.
25.
26.
Claudia Gedlicka Gudrun Hager Martina Weissenböck Wilhelm Gedlicka Birgit Knerer Johannes Kornfehl Michael Formanek 《Journal of oral pathology & medicine》2006,35(8):472-478
BACKGROUND: 1Alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2) Vitamin D(3)] induces growth inhibition in squamous cell carcinoma (SCC) cell lines of the head and neck by arresting the cells in the G0/G1 phase of the cell cycle, probably due to an enhanced expression of p21, which could be demonstrated in other cell lines (JPPA, SCC9) before. In SCC25, a SCC cell line isolated from tongue, growth inhibition but no overexpression of p21 was detected. The retinoblastoma gene, as a direct target of G1 cyclin-CDK complexes, showed an obvious shift from the hyperphosphorylated to the hypophosphorylated form under 1,25(OH)(2)Vitamin D(3), which indicates that the growth inhibition takes place in the G0/G1 phase. To explore the possible pathway of growth inhibition in SCC25 we investigated other cell cycle inhibitors (p18, p19, p27). METHODS: Synchronized cells were treated with 1,25(OH)(2)Vitamin D(3) over 96 h. The cell cycle status and expression of cell cycle-regulating proteins was determined by fluorescence-activated cell sorting (FACS) and Western blotting. An overexpression of p18 in 1,25(OH)(2)Vitamin D(3) vs. ethanol-treated cells was determined until 30 h in SCC25. No influence was detectable on the expression of p27 and p19. CONCLUSION: One mechanism by which 1,25(OH)(2)Vitamin D(3) controls cell growth might be the upregulation of p21. As p21 was unsusceptible to 1,25(OH)(2)Vitamin D(3) in SCC25, other inhibiting proteins were necessary to be tested. The proven upregulation of p18 seems to be the responsible step for growth inhibition of 1,25(OH)(2)Vitamin D(3) in SCC25. 相似文献
27.
28.
Michael D Levitt Julie K Furne Michael Kuskowski John Ruddy 《Clinical gastroenterology and hepatology》2006,4(2):123-129
BACKGROUND & AIMS: Breath methane measurements reflect the in situ activity of the methanogenic colonic flora. Thirty-five years ago we found that 34% of healthy adult subjects were methane producers (breath methane level >1 ppm above atmospheric methane levels). The current study presents a new survey of breath methane levels designed to determine if the activity of the methanogenic flora has changed over the past 35 years. In addition, we review insights into the methanogenic flora that have resulted from breath methane measurements. METHODS: The end-alveolar breath methane concentrations of 212 healthy adults living in the Minneapolis area were determined via gas chromatography. The influence of sex, age, and bowel movement frequency on methane production was assessed. RESULTS: The findings that 36.4% of participants were methane producers, with a mean methane concentration in these producers of 16.6 ppm, are strikingly similar to the values of 33.6% and 15.2 ppm observed 35 years ago. Neither sex nor age showed a statistically significant relationship to methane production. There was a negative correlation between frequency of bowel movements and breath methane concentration in methane producers. CONCLUSIONS: The activity of the methanogenic flora of healthy adults remained remarkably stable over the past 35 years despite widespread antibiotic use and dietary changes. A literature review revealed that many associations have been shown between methane production and clinical states, but it remains to be determined if methanogens actively influence human physiology or are simply a marker of colonic function. 相似文献
29.
30.
Angiotensin Converting Enzyme Inhibitors: Animal Experiments Suggest a New Pharmacological Treatment for Alcohol Abuse in Humans 总被引:1,自引:0,他引:1
G. Spinosa MSc E. Perlanski Dipl Tech. F. H. H. Leenen MD R. B. Stewart MSc L. A. Grupp DSc 《Alcoholism, clinical and experimental research》1988,12(1):65-70
The prevalence of heavy alcohol consumption is a major problem of increasing proportions throughout the world. Although alcohol sensitizing drugs and more recently serotonin uptake inhibitors are drug interventions with some following, their long term beneficial consequences have yet to be demonstrated. In recent years, we have demonstrated that manipulating activity in the renin-angiotensin system will dramatically alter voluntary alcohol consumption in rats. Based on these findings, the present study evaluated the ability of a class of drugs known as the angiotensin converting enzyme inhibitors to reduce voluntary alcohol drinking in laboratory animals. These drugs prevent the conversion of angiotensin I to angiotensin II. They have been licensed for use in Europe and North America and are indicated in the treatment of hypertension. Our experiments showed that both captopril (Capoten, Squibb) and enalapril (Vasotec, Merck Sharpe & Dohme) can reduce alcohol drinking in both normotensive and hypertensive animals regardless of whether the pattern of intake is in a bout or of a less exaggerated nature. Furthermore, this change in alcohol intake can occur without concomitant changes in blood pressure, plasma renin activity, overall fluid balance, or the distribution and metabolism of alcohol. Taken together these findings suggest that the angiotensin converting enzyme inhibitors should be evaluated in a clinical setting for they may prove to be a useful new treatment or treatment adjunct for alcohol abuse in humans. 相似文献