全文获取类型
收费全文 | 3499篇 |
免费 | 288篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 99篇 |
妇产科学 | 62篇 |
基础医学 | 401篇 |
口腔科学 | 82篇 |
临床医学 | 386篇 |
内科学 | 885篇 |
皮肤病学 | 58篇 |
神经病学 | 265篇 |
特种医学 | 149篇 |
外科学 | 379篇 |
综合类 | 87篇 |
一般理论 | 2篇 |
预防医学 | 403篇 |
眼科学 | 26篇 |
药学 | 175篇 |
中国医学 | 2篇 |
肿瘤学 | 309篇 |
出版年
2021年 | 53篇 |
2020年 | 22篇 |
2019年 | 61篇 |
2018年 | 63篇 |
2017年 | 47篇 |
2016年 | 58篇 |
2015年 | 29篇 |
2014年 | 69篇 |
2013年 | 129篇 |
2012年 | 165篇 |
2011年 | 163篇 |
2010年 | 104篇 |
2009年 | 99篇 |
2008年 | 164篇 |
2007年 | 176篇 |
2006年 | 186篇 |
2005年 | 170篇 |
2004年 | 178篇 |
2003年 | 120篇 |
2002年 | 138篇 |
2001年 | 130篇 |
2000年 | 145篇 |
1999年 | 95篇 |
1998年 | 44篇 |
1997年 | 44篇 |
1996年 | 42篇 |
1995年 | 35篇 |
1994年 | 38篇 |
1993年 | 39篇 |
1992年 | 79篇 |
1991年 | 64篇 |
1990年 | 77篇 |
1989年 | 65篇 |
1988年 | 71篇 |
1987年 | 60篇 |
1986年 | 55篇 |
1985年 | 47篇 |
1984年 | 36篇 |
1983年 | 38篇 |
1982年 | 22篇 |
1980年 | 19篇 |
1979年 | 38篇 |
1978年 | 23篇 |
1977年 | 22篇 |
1976年 | 22篇 |
1975年 | 22篇 |
1973年 | 19篇 |
1972年 | 18篇 |
1971年 | 18篇 |
1969年 | 18篇 |
排序方式: 共有3798条查询结果,搜索用时 15 毫秒
991.
Variance in diet-induced weight gain was examined for possible relationships with variations in early weight gain and three tests of behavioral responsivity. Female Sprague-Dawley rats were reared in litters of 4, 8, or 20. When animals reached adulthood, each animal's acoustic startle reflex, tail-pinch feeding responses and activity in an open field containing a palatable food were assessed. After completing these behavioral tests, rats were exposed to either palatable foods or a control diet for 59 days, following which all subjects were maintained on the control diet for 66 days. Body weights, food intakes, and naso-anal lengths were measured. Preweaning body weight gain for all rats correlated positively with later diet-induced weight gain. Rats reared in litters of 4 or 20 both gained less weight after exposure to palatable foods than did rats reared in litters of 8. Diet-induced weight gain correlated positively with magnitude of acoustic startle reflex and with latency to eat in response to tail pinch. These results tentatively identify specific predictive factors which may be useful in future studies of dietary obesity. 相似文献
992.
Huang MX Shih JJ Lee RR Harrington DL Thoma RJ Weisend MP Hanlon F Paulson KM Li T Martin K Millers GA Canive JM 《Brain topography》2004,16(3):139-158
A number of beamformers have been introduced to localize neuronal activity using magnetoencephalography (MEG) and electroencephalography (EEG). However, currently available information about the major aspects of existing beamformers is incomplete. In the present study, detailed analyses are performed to study the commonalities and differences among vectorized versions of existing beamformers in both theory and practice. In addition, a novel beamformer based on higher-order covariance analysis is introduced. Theoretical formulas are provided on all major aspects of each beamformer; to examine their performance, computer simulations with different levels of correlation and signal-to-noise ratio are studied. Then, an empirical data set of human MEG median-nerve responses with a large number of neuronal generators is analyzed using the different beamformers. The results show substantial differences among existing MEG/EEG beamformers in their ways of describing the spatial map of neuronal activity. Differences in performance are observed among existing beamformers in terms of their spatial resolution, false-positive background activity, and robustness to highly correlated signals. Superior performance is obtained using our novel beamformer with higher-order covariance analysis in simulated data. Excellent agreement is also found between the results of our beamformer and the known neurophysiology of the median-nerve MEG response. 相似文献
993.
Harrington LC Françoisevermeylen Jones JJ Kitthawee S Sithiprasasna R Edman JD Scott TW 《Journal of medical entomology》2008,45(2):307-313
The assumption that mosquito survival remains constant and that it is independent of age was tested with free-ranging Aedes aegypti (L.) (Diptera: Culicidae) by using a "synthetic cohort" mark-release-recapture method. Mosquito age cohorts (1-2, 3-4, and 19-20 d) were released simultaneously in homes in rural Thai villages during dry and rainy seasons (2002). Significant age-dependent effects were detected during the dry and rainy seasons. More young than older mosquitoes were recaptured (1-4 versus 5-20 d). The best predictive fit for recaptures was obtained using a quadratic function of age. Our results provide the first field-based evidence for age-dependent Ae. aegypti mortality in which the death rate increases with advancing age and highlight the need for research on ecological and epidemiological aspects of this process. 相似文献
994.
995.
Understanding mosquito mating biology is essential for studies of mosquito behavior, gene flow, population structure, and genetic control. In the current study, we examine the effect of age and body size on spermatozoa number in two laboratory strains of the dengue vector, Aedes aegypti (L.), Thailand and Rockefeller (ROCK), and in wild-collected mosquitoes from Thailand. Body size was a major predictor of total spermatozoa number, with significantly greater sperm numbers in large (2.27-mm wing length) versus small males (1.85-mm wing length) within the same age group. Total sperm capacity also varied by male age. Spermatozoa numbers in virgin Ae. aegypti males increased significantly up to 10 d after emergence and then leveled off until 20 d. Significant variations in sperm number were detected among Ae. aegypti strains, with wild-collected mosquitoes having the greatest total number of sperm. Our study provides the first evidence of spermatogenesis in adult mosquitoes and indicates high rates of spermatogenesis in male mosquitoes up to 10 d of age (3.3 degree-days). Our results emphasize the potential role of body size and age on the mating capacity of this important vector of dengue and yellow fever viruses. 相似文献
996.
Lawrence ��LB�� Brown 《Journal of the National Medical Association》2004,96(12):1679-1679
997.
998.
S H Sadow C A Murray R F Wilson S Mansoori S D Harrington 《The Annals of thoracic surgery》1988,45(6):682-683
A 14-year-old male pedestrian was hit by a truck and admitted with respiratory distress and subcutaneous emphysema. Aortography revealed disruption of the ascending aorta. Bronchoscopy revealed rupture of the left main bronchus at the carina. Both lesions were repaired using a median sternotomy, cardiopulmonary bypass, and a transpericardial approach for the bronchial repair. To our knowledge, this is the first report of successful repair of a combined rupture of a major bronchus and the ascending aorta. 相似文献
999.
I L Abraham A A Thompson-Heisterman D P Harrington D E Smullen L L Onega E G Droney P S Westerman C A Manning P A Lichtenberg 《Archives of Psychiatric Nursing》1991,5(3):151-164
The complex needs of psychogeriatric patients and their families require specialized outpatient psychogeriatric services. The interaction of physical and mental health and the need for coordinated care places important responsibilities on nursing because it contributes to integrated, multidisciplinary care delivery to these patients and their families. This article presents a model of outpatient psychogeriatric nursing services focused on the community integration of patients and families. Experiences in the development of the Geriatric Neuropsychiatry Clinic at the University of Virginia, Charlottesville, are used as the point of departure from which to describe a model of outpatient psychogeriatric nursing care delivery that is multidisciplinary, clinically innovative, and epidemiologically justified. 相似文献
1000.
S. Husted R. A. Harrington C. P. Cannon R. F. Storey P. Mitchell H. Emanuelsson 《International journal of clinical practice》2009,63(4):667-670
AZD6140, the first reversible oral P2Y12 receptor antagonist, exhibits greater and more consistent inhibition of platelet aggregation than the irreversible thienopyridine clopidogrel. As a result of its reversible effect, AZD6140 may pose less risk for bleeding when antiplatelet treatment cannot be stopped at least 5 days before coronary artery bypass graft (CABG) surgery or other invasive procedures. The Dose conflrmation Study assessing anti‐Platelet Effects of AZD6140 vs. clopidogRel in NSTEMI (DISPERSE2) trial showed overall comparable bleeding rates with antiplatelet treatment with AZD6140 90 mg twice daily or 180 mg twice daily vs. clopidogrel 75 mg once daily in 984 patients with non‐ST‐elevation acute coronary syndromes. A post hoc exploratory analysis of bleeding outcomes in the subset of 84 patients undergoing CABG in DISPERSE2 suggests reduced risk for total bleeding (41% and 58% vs. 62%), all major bleeding (38% and 50% vs. 62%), and life‐threatening bleeding (22% and 38% vs. 54%) with AZD6140 90 mg (n = 32) and 180 mg (n = 26) vs. clopidogrel (n = 26) respectively. Trends suggested that major bleeding rates were reduced with AZD6140 (combined groups) vs. clopidogrel when treatment was stopped ≤ 5 days prior to surgery (39% vs. 63%, p = 0.15) but not when treatment was stopped > 5 days before surgery (50% vs. 60%). This observation is consistent with the reversible binding of AZD6140 to the P2Y12 receptor. Further prospective studies are planned to assess the relationship between this potential clinical benefit of AZD6140 and the reversibility of its antiplatelet effects. 相似文献