全文获取类型
收费全文 | 718047篇 |
免费 | 49435篇 |
国内免费 | 1351篇 |
专业分类
耳鼻咽喉 | 9372篇 |
儿科学 | 23510篇 |
妇产科学 | 17718篇 |
基础医学 | 111843篇 |
口腔科学 | 20294篇 |
临床医学 | 64469篇 |
内科学 | 137485篇 |
皮肤病学 | 16598篇 |
神经病学 | 50207篇 |
特种医学 | 26272篇 |
外国民族医学 | 76篇 |
外科学 | 106744篇 |
综合类 | 14865篇 |
现状与发展 | 2篇 |
一般理论 | 163篇 |
预防医学 | 51712篇 |
眼科学 | 16438篇 |
药学 | 54630篇 |
3篇 | |
中国医学 | 2372篇 |
肿瘤学 | 44060篇 |
出版年
2021年 | 5653篇 |
2018年 | 8060篇 |
2017年 | 6265篇 |
2016年 | 7002篇 |
2015年 | 7740篇 |
2014年 | 10505篇 |
2013年 | 15695篇 |
2012年 | 21041篇 |
2011年 | 22072篇 |
2010年 | 13052篇 |
2009年 | 12239篇 |
2008年 | 20543篇 |
2007年 | 22119篇 |
2006年 | 22478篇 |
2005年 | 21041篇 |
2004年 | 20540篇 |
2003年 | 19533篇 |
2002年 | 18978篇 |
2001年 | 36752篇 |
2000年 | 37318篇 |
1999年 | 30761篇 |
1998年 | 8022篇 |
1997年 | 6808篇 |
1996年 | 7094篇 |
1995年 | 6727篇 |
1994年 | 6189篇 |
1993年 | 5667篇 |
1992年 | 23231篇 |
1991年 | 23164篇 |
1990年 | 22559篇 |
1989年 | 22318篇 |
1988年 | 20259篇 |
1987年 | 19663篇 |
1986年 | 18688篇 |
1985年 | 17538篇 |
1984年 | 12821篇 |
1983年 | 10863篇 |
1982年 | 5983篇 |
1979年 | 11639篇 |
1978年 | 8184篇 |
1977年 | 6882篇 |
1976年 | 6645篇 |
1975年 | 7313篇 |
1974年 | 8555篇 |
1973年 | 8214篇 |
1972年 | 7707篇 |
1971年 | 7175篇 |
1970年 | 6915篇 |
1969年 | 6345篇 |
1968年 | 5818篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
31.
N Jastrow E Antonelli R Robyr O Irion M Boulvain 《Ultrasound in obstetrics & gynecology》2006,27(4):420-424
OBJECTIVE: To evaluate the reproducibility of sonographic measurement of the lower uterine segment in pregnant women at term. METHODS: Two independent observers performed transabdominal sonography on 129 women between 36 and 38 weeks of gestation who had had a previous Cesarean section. Sonography was performed when the patients had a full and a half-full bladder; in 100 patients, the measurements were also performed transvaginally, with the patients having an empty bladder. Agreement was quantified by the intraclass correlation coefficient and, using a cut-off of 3.5 mm, by the kappa coefficient. RESULTS: The intraobserver agreement was generally high (intraclass correlation coefficient > 0.90). The interobserver agreement was higher on transvaginal (intraclass correlation coefficient, 0.94) compared with transabdominal (0.70 and 0.84, with full and half-full bladder, respectively) ultrasound. The kappa coefficient was 0.75 transvaginally, compared with 0.34 and 0.54 using the transabdominal approach, with full and half-full bladder, respectively. CONCLUSION: The agreement between two observers for sonographic transvaginal measurement of the lower uterine segment can be considered good, compared with poor to moderate agreement using the transabdominal approach. 相似文献
32.
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
33.
S Chinn S H Downs J M Anto M W Gerbase B Leynaert R de Marco C Janson D Jarvis N Künzli J Sunyer C Svanes E Zemp U Ackermann-Liebrich P Burney 《The European respiratory journal》2006,28(4):763-771
The incidence of asthma has been reported to be associated with obesity. An alternative analysis, of net change in prevalence, does not require exclusion of those with asthma at baseline. Follow-up data were obtained from 9,552 participants in the European Community Respiratory Health Survey and the Swiss cohort Study on Air Pollution and Lung Disease in Adults. Incidence of asthma was analysed by proportional hazards regression, and net changes in symptoms and asthma status by generalised estimating equations, by obesity group. Incidence and net change in ever having had asthma were greater in females than in males, and in participants who remained obese compared with those who were never obese (hazard ratio 2.00, 95% confidence interval 1.25-3.20; excess net change 2.8%, 0.4-5.3% per 10 yrs). The effect of being obese on net change in diagnosed asthma was greater in females than in males, but for net change in wheeze without a cold it was greater in males. The present results are consistent with asthma being more frequently diagnosed in females, especially obese females. These findings may help to explain the reports of a stronger association between asthma and obesity in females than in males. 相似文献
34.
35.
36.
C G Arruda J M Aldrighi L A Bortolotto I N Alecrin J A F Ramires 《Gynecological endocrinology》2006,22(10):557-563
BACKGROUND: Arterial hypertension and postmenopausal reduction of estrogen levels may be involved in modifications of the stiffness of large arteries. OBJECTIVES: To evaluate the pulse-wave velocity (PWV) and indirectly the arterial stiffness in hypertensive postmenopausal women submitted to hormone therapy with estradiol alone or combined with norethisterone acetate. SUBJECTS: Forty-five hypertensive postmenopausal women were double-blindly, randomly assigned to three arms of treatment: placebo (group I); estradiol 2 mg/day (group II); or estradiol 2 mg/day and norethisterone acetate 1 mg/day (group III). METHODS: Arterial stiffness was assessed from PWV measurements of the common carotid and femoral arteries (CF-PWV) and the common carotid and radial arteries (CR-PWV) obtained using the automatic Complior(R) device, taken at baseline and after 12 weeks of treatment. RESULTS: After the 12-week treatment, values of CF-PWV and CR-PWV were not significantly different (p = 0.910 and p = 0.736, respectively) among the groups. Systolic blood pressure showed a positive correlation with CF-PWV in groups II and III (p = 0.02 and p < 0.001, respectively). CONCLUSIONS: PWV and arterial stiffness in postmenopausal hypertensive women did not reduce over a 12-week treatment with estradiol alone compared with the same period of treatment with estradiol combined with norethisterone acetate. 相似文献
37.
38.
G N J Tytgat 《Acta chirurgica. Supplement》2002,(587):77-81
A true comparison of long-term medical and surgical treatment in gastro-oesophageal reflux disease (GORD) is impossible as few studies have been carried out with adequate randomisation of the patients and long-term evaluation of quality of life. In general the control of the reflux symptoms is roughly equal with medical and surgical treatment. However, surgery can cause other symptoms such as dysphagia or non-specific epigastric discomfort or pain in some patients, which reduces the overall efficacy in controlling the symptoms. Based on a cost utility analysis, Heudebert et al. came to the conclusion that medical treatment was their preferred strategy for most patients with severe erosive oesophagitis. 相似文献
39.
40.