全文获取类型
收费全文 | 2402437篇 |
免费 | 174441篇 |
国内免费 | 3453篇 |
专业分类
耳鼻咽喉 | 32797篇 |
儿科学 | 77042篇 |
妇产科学 | 63742篇 |
基础医学 | 354850篇 |
口腔科学 | 65947篇 |
临床医学 | 215463篇 |
内科学 | 470122篇 |
皮肤病学 | 53037篇 |
神经病学 | 189897篇 |
特种医学 | 89187篇 |
外国民族医学 | 489篇 |
外科学 | 361162篇 |
综合类 | 47751篇 |
现状与发展 | 12篇 |
一般理论 | 869篇 |
预防医学 | 187348篇 |
眼科学 | 55294篇 |
药学 | 178541篇 |
11篇 | |
中国医学 | 4756篇 |
肿瘤学 | 132014篇 |
出版年
2021年 | 19941篇 |
2019年 | 20559篇 |
2018年 | 28847篇 |
2017年 | 21411篇 |
2016年 | 23820篇 |
2015年 | 27295篇 |
2014年 | 37810篇 |
2013年 | 56479篇 |
2012年 | 79321篇 |
2011年 | 83905篇 |
2010年 | 49230篇 |
2009年 | 46151篇 |
2008年 | 78423篇 |
2007年 | 83445篇 |
2006年 | 84387篇 |
2005年 | 81585篇 |
2004年 | 77823篇 |
2003年 | 74771篇 |
2002年 | 72349篇 |
2001年 | 109594篇 |
2000年 | 112554篇 |
1999年 | 94088篇 |
1998年 | 27145篇 |
1997年 | 23773篇 |
1996年 | 24172篇 |
1995年 | 22828篇 |
1994年 | 20982篇 |
1993年 | 19800篇 |
1992年 | 72097篇 |
1991年 | 70159篇 |
1990年 | 68448篇 |
1989年 | 65730篇 |
1988年 | 60340篇 |
1987年 | 59171篇 |
1986年 | 55264篇 |
1985年 | 53061篇 |
1984年 | 39390篇 |
1983年 | 33447篇 |
1982年 | 19927篇 |
1979年 | 35902篇 |
1978年 | 25683篇 |
1977年 | 21265篇 |
1976年 | 20360篇 |
1975年 | 21839篇 |
1974年 | 26178篇 |
1973年 | 24825篇 |
1972年 | 23204篇 |
1971年 | 22046篇 |
1970年 | 20259篇 |
1969年 | 19326篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
R E Dales A Mehdizadeh S D Aaron K L Vandemheen J Clinch 《The European respiratory journal》2006,28(2):319-322
The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting. Patients aged >or=35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females. Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively). In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction. 相似文献
72.
L Bernardi A Schneider L Pomidori E Paolucci A Cogo 《The European respiratory journal》2006,27(1):165-171
A very high ventilatory response to hypoxia is believed necessary to reach extreme altitude without oxygen. Alternatively, the excessive ventilation could be counterproductive by exhausting the ventilatory reserve early on. To test these alternatives, 11 elite climbers (2004 Everest-K2 Italian Expedition) were evaluated as follows: 1) at sea level, and 2) at 5,200 m, after 15 days of acclimatisation at altitude. Resting oxygen saturation, minute ventilation, breathing rate, hypoxic ventilatory response, maximal voluntary ventilation, ventilatory reserve (at oxygen saturation = 70%) and two indices of ventilatory efficiency were measured. Everest and K2 summits were reached 29 and 61 days, respectively, after the last measurement. Five climbers summited without oxygen, the other six did not, or succeeded with oxygen (two climbers). At sea level, all data were similar. At 5,200 m, the five summiters without oxygen showed lower resting minute ventilation, breathing rate and ventilatory response to hypoxia, and higher ventilatory reserve and ventilatory efficiency, compared to the other climbers. Thus, the more successful climbers had smaller responses to hypoxia during acclimatisation to 5,200 m, but, as a result, had greater available reserve for the summit. A less sensitive hypoxic response and a greater ventilatory efficiency might increase ventilatory reserve and allow sustainable ventilation in the extreme hypoxia at the summit. 相似文献
73.
74.
75.
T. Svara M. Gombac M. Vrecl P. Juntes R. Kostanjsek A. Pogacnik M. Pogacnik 《Transboundary and Emerging Diseases》2006,53(1):26-29
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm. 相似文献
76.
77.
78.
A new semi-empirical formula for the evaluation of (n,(3)He) reaction cross-sections at the energy of 14.6 and 20 MeV is presented. Formula was derived using the analytical expression for the evaluation of the (3)He spectrum within the frame of pre-equilibrium exciton model. The systematics obtained is compared with the empirical formula for the (n,(3)He) reaction cross-section. 相似文献
79.
Mahmoud R Hussein Dalia A Elsers Sabah A Fadel Abd-Elhady M Omar 《European journal of cancer prevention》2006,15(1):64-68
Although melanocytic skin lesions have been recognized since antiquity, their literature was limited to Caucasians. To date, the clinicopathologic features of these lesions in Egyptians are still unknown. To define these features, diagnostic records of the melanocytic skin lesions received at the Pathology Department, Assuit University Hospitals (1989-2004) were reviewed. The lesions examined included 12 benign naevi (BN), 10 dysplastic naevi (DN), and 21 cutaneous malignant melanomas (CMMs). The DN and CMMs were more common in men than in women (2 : 1 and 1.5 : 1, respectively) while BN were more common in women (2 : 1). The average age incidence was 33+/-5, 38+/-7 and 54+/-3 years, for BN, DN and CMM, respectively. The lower limb (13/21, 62%), head and neck (7/21, 33%) were the most common sites for CMMs. The average size (mm) was 2+/-0.3, 4+/-0.6 and 21+/-0.3 for BN, DN and CMMs, respectively. Recurrence occurred in 10% of CMMs. Histologically, CMMs were of nodular type and composed of epithelioid (7/21, 33%), spindle cells (1/21, 5%), or mixed cells (13/21, 62%). The mean tumour thickness (Breslow) was 6+/-0.5 mm. CMMs included two of 21(9%), three of 21(14%), six of 21(38%), and 10 of 21(38%) with Clark level II, III, IV and V. In Egypt, CMM is the third most common cutaneous neoplasm following squamous and basal cell carcinomas. Compared with Western societies, melanoma has a male sex predilection, similar histological features but different topographical distribution and rare incidence. The striking difference from Western series is the incidence of nodular melanoma - in the West this represents 15-30% of melanomas, with superficial spreading being the majority. Another key difference from the West is the 'sun-bed' culture of the West and the desire to have suntans. This is the first study that reports the clinicopathologic features of melanocytic skin lesions in Egypt. 相似文献
80.