全文获取类型
收费全文 | 2354篇 |
免费 | 250篇 |
国内免费 | 74篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 54篇 |
妇产科学 | 102篇 |
基础医学 | 237篇 |
口腔科学 | 33篇 |
临床医学 | 251篇 |
内科学 | 408篇 |
皮肤病学 | 9篇 |
神经病学 | 223篇 |
特种医学 | 64篇 |
外科学 | 262篇 |
综合类 | 248篇 |
预防医学 | 387篇 |
眼科学 | 20篇 |
药学 | 168篇 |
中国医学 | 20篇 |
肿瘤学 | 178篇 |
出版年
2024年 | 26篇 |
2023年 | 113篇 |
2022年 | 221篇 |
2021年 | 192篇 |
2020年 | 152篇 |
2019年 | 129篇 |
2018年 | 108篇 |
2017年 | 74篇 |
2016年 | 107篇 |
2015年 | 59篇 |
2014年 | 166篇 |
2013年 | 188篇 |
2012年 | 125篇 |
2011年 | 128篇 |
2010年 | 90篇 |
2009年 | 97篇 |
2008年 | 112篇 |
2007年 | 96篇 |
2006年 | 82篇 |
2005年 | 60篇 |
2004年 | 47篇 |
2003年 | 36篇 |
2002年 | 29篇 |
2001年 | 24篇 |
2000年 | 29篇 |
1999年 | 28篇 |
1998年 | 21篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有2678条查询结果,搜索用时 15 毫秒
1.
2.
The aim of this study was to evaluate whether a prevalent vertebral deformity predicts mortality and fractures in both men and women. In the city of Malmö, 598 individuals (298 men, 300 women; age 50–80 years) were selected from the city's population and were included in the Swedish part of the European Vertebral Osteoporosis Study (EVOS). At baseline the participants answered a questionnaire and lateral spine radiographs were performed. The prevalence of subjects with vertebral deformity was assessed using a morphometric method. The mortality during a 10-year follow-up period was determined through the register of the National Swedish Board of Health and Welfare. Eighty-five men and 43 women died during the study period. The subsequent fracture incidence during the follow-up period was ascertained by postal questionnaires, telephone interviews and by a survey of the archives of the Department of Radiology in the city hospital. Thirty-seven men and 69 women sustained a fracture during the study period. Data are presented as hazard ratios (HR) with 95% confidence interval (95% CI) within brackets. Prevalent vertebral deformity, defined as a reduction by more than 3 standard deviations (SD) in vertebral height ratio, predicted mortality during the forthcoming decade in both men [age-adjusted HR 2.4 (95% CI 1.6–3.9)] and women [age-adjusted HR 2.3 (95% CI 1.3–4.3)]. In men there was an increased mortality due to cardiovascular and pulmonary diseases and in women due to cancer. Prevalent vertebral deformity predicted an increased risk of any fracture during the forthcoming decade in both men [age-adjusted HR 2.7 (95% CI 1.4–5.3)] and women [age-adjusted HR 1.8 (95% CI 1.1–2.9)]. Prevalent vertebral deformity predicted an increased risk of any subsequent fragility fracture in women [age-adjusted HR 2.0 (95% CI 1.1–3.5)]; however, in men the increased risk was nonsignificant [age-adjusted HR 1.9 (95% CI 0.7–5.1)]. In summary, a prevalent vertebral deformity can predict both increased mortality and increased fracture incidence during the following decade in both men and women. We conclude that prevalent vertebral deformity could be used as a risk factor in both genders for mortality and future fracture. 相似文献
3.
喻林 《湖北民族学院学报(医学版 )》1994,(2)
本文通过对131例妊娠中晚期胎儿的股骨长度(FL)、胎盘分级(PG),胎头双顶径(BPD)羊水(AF)等超声显象观测,探讨了FL对预测胎儿成熟度的价值,并分析了四者之间的相互关系,发现不同胎龄儿FL不同,FL随胎龄增加而增长,并与PG、BPD呈正相关关系,作者认为FL是判断胎儿成熟的有效指标。 相似文献
4.
Colonoscopy is sometimes painful for the patient and often difficult for the endoscopist, but it is hard to predict how difficult or painful the examination will be. The purpose of this study was to identify factors that influence difficulty and pain during colonoscopy.Some 1,284 consecutive patients undergoing office colonoscopy by three endoscopists were prospectively studied. A standard questionnaire was completed by the nursing staff, who assessed the degree of difficulty and pain associated with each exam on a four-point scale.There were 682 men and 551 women (sex not recorded in 51). There was no pain in 27%, mild pain in 39%, moderate pain in 25%, and severe pain in 9%. There was no difficulty in 25%, mild difficulty in 33%, moderate difficulty in 28%, and severe difficulty in 14%. Colonoscopy was significantly easier (P<0.001, chi square) and less painful (P<0.001, chi square) in patients after sigmoidectomy. It was more painful after hysterectomy (P<0.05, chi square) and more difficult and painful in women than in men (P<0.01, chi square). There were significant differences between endoscopists in the assessment of pain associated with colonoscopy.Most colonoscopies are associated with little or no pain (66%) and are easy or only mildly difficult to perform (58%). Patients who have had sigmoid resection are especially easy and painless to examine while women, especially after hysterectomy, are at higher risk of having a painful experience. Colonoscopy technique can influence the amount of pain experienced by the patient. 相似文献
5.
Human smooth pursuit during transient perturbations of predictable and unpredictable target movement
A. V. van den Berg 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1988,72(1):95-108
Summary The predictive component of human smooth pursuit was studied by perturbing sinusoidal target motion at unpredictable instants. The disturbances consisted of either a brief period of stabilization of the target on the fovea or a replacement of the sine by a ramp displacement for half a period. To minimize the effects of a possible change of the tracking strategy by the subject the transitions were masked and only the initial part of the response to the disturbance was analyzed. After stabilization on the fovea the eye oscillation continued at the frequency of the preceding target movement for about one half-cycle, whereupon the oscillation was rapidly damped. The mean unidirectional smooth eye acceleration was 70% of the mean unidirectional target acceleration prior to the stabilization. This suggests that during pursuit of a sinusoidal target movement about 75% of the oculomotor response is generated by predictive processes. When the sine was replaced by a ramp, starting at the velocity zero-crossing, the eye accelerated away from the target for ca. 180 ms irrespective of the frequency of prior tracking. In contrast, when the ramp started at the peak velocity of the sinusoidal target motion the eye accelerated away from the target for more than a quarter period. After foveal stabilization during pursuit of a pseudorandom stimulus, the eye continued to oscillate for less than one period at approximately the highest frequency present in the stimulus. The frequency characteristics of human smooth pursuit of predictable as well as unpredictable target motion were correctly simulated by a model, which derived its predictive properties from a lead element, tuned to the current frequency of the target motion. 相似文献
6.
Mehnert P Malchaire J Kampmann B Piette A Griefahn B Gebhardt H 《European journal of applied physiology》2000,82(1-2):52-60
The prediction of the mean skin temperature used for the Required Sweat Rate index was criticised for not being valid in
conditions with high radiation and high humidity. Based on a large database provided by 9 institutes, 1999 data points obtained
using steady-state conditions, from 1399 experiments and involving 377 male subjects, were used for the development of a new
prediction model. The observed mean skin temperatures ranged from 30.7 °C to 38.6 °C. Experimental conditions included air
temperatures (T
a) between 20 and 55 °C, mean radiant temperatures (T
r) up to 145 °C, partial vapour pressures (P
a) from 0.2 to 5.3 kPa, air velocities (v
a) between 0.1 and 2 m/s, and metabolic rates (M) from 102 to 620 W. Rectal temperature (T
re) was included in the models to increase the accuracy of prediction. Separate models were derived for nude (clothing insulation,
Icl, ≤0.2 clo, where 1 clo=0.155 m2 · °C · W−1, which is equivalent to the thermal insulation of clothing necessary to maintain a resting subject in comfort in a normally
ventilated room, air movement=10 cm/s, at a temperature of 21 °C and a humidity of less than 50%) and clothed (0.6 ≤ Icl ≤ 1.0 clo) subjects using a multiple linear regression technique with re-sampling (non-parametric bootstrap). The following
expressions were obtained for nude and clothed subjects, respectively: T
sk=7.19 + 0.064T
a + 0.061T
r + 0.198P
a− 0.348v
a + 0.616T
re and T
sk=12.17 + 0.020T
a + 0.044T
r + 0.194P
a − 0.253v
a + 0.0029M + 0.513T
re. For the nude and clothed subjects, 83.3% and 81.8%, respectively, of the predicted skin temperatures were within the range
of ±1 °C of the observed skin temperatures. It is concluded that the proposed models for the prediction of the mean skin temperature
are valid for a wide range of warm and hot ambient conditions in steady-state conditions, including those of high radiation
and high humidity.
Accepted: 7 February 2000 相似文献
7.
Bonifacio E Mollenhauer U Buuck D Ziegler AG 《Clinical immunology (Orlando, Fla.)》2005,115(2):173-177
Autoimmunity may be associated with acute or chronic inflammation. In order to determine whether the inflammatory marker C-reactive protein (CRP) was an indicator of inflammatory events that precede, predict, or associate with islet autoimmunity or type 1 diabetes, CRP was measured in sequential antibody-negative, seroconversion, and follow-up-positive samples from 65 prospectively studied islet autoantibody-positive children. Although changes in CRP concentrations were observed in some children, overall CRP concentrations were similar in antibody-negative samples (median, 0.21 mg/L), antibody-positive samples (median, 0.26 mg/L), and samples at seroconversion (median, 0.26 mg/L). CRP concentrations at diabetes onset (median, 0.59 mg/L) were not significantly increased over antibody-negative samples (P = 0.07). CRP concentrations did not predict diabetes development. CRP concentrations were related to age (r = 0.26; P < 0.001) and were increased in samples obtained from October to January (P < 0.001). These findings suggest that CRP concentrations are not a valuable marker of progression to type 1 diabetes and highlight the importance of correcting analyses for seasonal variations. 相似文献
8.
Jochen Fahrenberg Fritz Foerster Hermann-Josef Schneider Wolfgang Müller Michael Myrtek 《Psychophysiology》1986,23(3):323-333
The predictability of individual differences in activation processes was investigated in a multi-method laboratory-field study. Male students of physical education (N=58) were examined under various emotionally activating and physically demanding conditions (mental arithmetic, reaction time, free speech, cold pressor test, bicycle ergometer). The assessment included multi-channel recordings of pre-start phases in an athletic stadium and performance on a 1000 m run. Basal heart rate was also recorded during sleep. This multi-situational assessment was repeated after three weeks, three months, and, for most (N=42) subjects, after one year. Significant relationships exist between scores from corresponding conditions of relaxation, anticipation, and performance of physical exercise. However, with the exception of heart rate, correlation coefficients are rather small and seem to be of questionable predictive validity. A generalizability study further supports the general conclusion: To increase the practical relevance in psychophysiological investigations of stress/strain phenomena, such studies should directly assess individual differences in the criterion situations themselves. 相似文献
9.
S. G. Wells Graham R. Barnes 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1998,120(1):129-133
Anticipatory smooth pursuit before the expected appearance of a moving target can reduce the initial retinal blur caused by
the 100-ms delay of visual feedback. Humans, though, can only voluntarily generate smooth velocities up to about 5°/s without
a moving target. However, previous experiments have shown that repetitive brief presentations of a moving target every few
seconds appear to charge an internal store, the contents of which can later be released to generate higher velocity anticipatory
movements. This store’s longevity was assessed here by repetitively presenting a moving target for 500 ms at different known
intervals up to 7.2 s. Target motion at 25°/s or 50°/s was tested, with presentations in alternate directions or the same
direction. Anticipatory velocity, measured 100 ms after target onset, decreased with increasing interval for all target motion
conditions. A decrease was still seen when accurate timing cues were given before each presentation, suggesting that the drive
for anticipatory pursuit is held in a short-term store lasting a few seconds which can enhance the low velocities produced
by volition alone. The results also demonstrate that high-velocity anticipatory pursuit helps to overcome the temporal delays
in the system and allows target velocity to be matched at an earlier time.
Received: 27 August 1997 / Accepted: 22 December 1997 相似文献
10.
目的 对身体形态指数(ABSI)和身体圆度指数(BRI)的发展进行介绍,并对其应用情况进行综述,为人体形态测量提供参考。方法 在Pubmed、中国知网等电子文献数据库中进行文献检索,详尽收录迄今ABSI与BRI对高血压、糖尿病、代谢综合征、心血管疾病等常见疾病的发病率以及全因死亡率预测的相关研究。结果 ABSI与BRI均对高血压、糖尿病、代谢综合征、心血管疾病发病呈现出一定的预测能力。其中,BRI在预测糖尿病、代谢综合征发病方面优于ABSI,但与身体质量指数、腰围、臀围、腰高比等传统测量指标相比,并未表现出显著的差异。ABSI对全因死亡率的预测能力则明显优于传统测量指标和BRI。结论 ABSI与BRI作为两项新的形态学指标,是BMI等传统身体指数测量的补充,对疾病发病具有一定的预测能力和应用性。今后的研究可以从两项指标对疾病的单独作用以及与传统指标的联合作用着手,同时探索其在不同社会人口学特征人群中的拟合情况,提供更有利的研究证据和科学积累。 相似文献