全文获取类型
收费全文 | 44039篇 |
免费 | 2385篇 |
国内免费 | 154篇 |
专业分类
耳鼻咽喉 | 563篇 |
儿科学 | 2790篇 |
妇产科学 | 751篇 |
基础医学 | 5132篇 |
口腔科学 | 1360篇 |
临床医学 | 3172篇 |
内科学 | 8008篇 |
皮肤病学 | 1273篇 |
神经病学 | 2718篇 |
特种医学 | 1284篇 |
外科学 | 6640篇 |
综合类 | 1347篇 |
一般理论 | 18篇 |
预防医学 | 2208篇 |
眼科学 | 1604篇 |
药学 | 4333篇 |
中国医学 | 380篇 |
肿瘤学 | 2997篇 |
出版年
2023年 | 316篇 |
2022年 | 813篇 |
2021年 | 1749篇 |
2020年 | 955篇 |
2019年 | 1087篇 |
2018年 | 1508篇 |
2017年 | 1122篇 |
2016年 | 1458篇 |
2015年 | 1486篇 |
2014年 | 2177篇 |
2013年 | 2504篇 |
2012年 | 3535篇 |
2011年 | 3485篇 |
2010年 | 2059篇 |
2009年 | 1630篇 |
2008年 | 2353篇 |
2007年 | 2371篇 |
2006年 | 2129篇 |
2005年 | 1920篇 |
2004年 | 1780篇 |
2003年 | 1492篇 |
2002年 | 1301篇 |
2001年 | 804篇 |
2000年 | 734篇 |
1999年 | 626篇 |
1998年 | 296篇 |
1997年 | 236篇 |
1996年 | 234篇 |
1995年 | 198篇 |
1994年 | 168篇 |
1993年 | 142篇 |
1992年 | 371篇 |
1991年 | 351篇 |
1990年 | 368篇 |
1989年 | 342篇 |
1988年 | 293篇 |
1987年 | 253篇 |
1986年 | 241篇 |
1985年 | 237篇 |
1984年 | 181篇 |
1983年 | 125篇 |
1982年 | 76篇 |
1981年 | 83篇 |
1980年 | 77篇 |
1979年 | 122篇 |
1978年 | 84篇 |
1977年 | 91篇 |
1976年 | 70篇 |
1973年 | 65篇 |
1971年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Restriction maps of the rDNA cistron of twelve species of mosquitoes in six genera of the subfamily Culicinae were constructed using eight 6 bp recognition restriction enzymes. Anopheles albimanus was used as an outgroup. The size of the rDNA cistron ranged from 8.5 kb in Aedes katherinensis to 12.9 kb in Ae. polynesiensis. A total of twenty-six sites were scored; eighteen were polymorphic among ingroup taxa. The proportion of polymorphic nucleotide sites (Pnuc) was 0.059 and the heterozygosity per nucleotide site (Hnuc) was 0.028. Wagner and Fitch Parsimony, Dollo Parsimony and Nei-Li distance/neighbour-joining methods were used to construct phylogenetic trees. The rDNA RFLP dataset did not provide a well-supported phylogeny among culicine taxa. The RFLP phylogenies are incongruent with the morphology character based and molecular phylogenies and derived relationships did not correspond with current taxonomic classifications. The lack of resolution was due to homoplasy arising from frequent independent loss or gain of restriction sites among unrelated taxa. 相似文献
62.
A retrospective longitudinal study of 105 penetrating keratoplasties for vascularized corneal opacities was done. The results of cases with an etiology of healed trachoma or healed corneal ulcers were compared. The vascularization was graded from Grade I to V depending on the quadrant and type of vascularization. Graft clarity of 2+ or more in cases of trachomatous opacity was achieved in 93% of cases and that after postinfectious opacity in 71.8%. Prognosis was poor in cases where deep vascularization was present in more than two quadrants or more than 180 degrees. 相似文献
63.
M S Sachdev H Kumar A K RoopJain R Arora V K Dada 《Indian journal of ophthalmology》1990,38(4):184-186
A case of destructive ocular myiasis resulting in complete loss of the globe in two days time is documented. To the best of our knowledge this is the first report of such a severe involvement in a healthy and non-compromised host. Mechanical removal and good local hygiene helped heal the wound. The larvae were isolated to be that of Chrysomyia bezziana (screwworm fly). This is possibly the first report of destructive ocular myiasis caused by Chrysomyia bezziana from the Indian subcontinent and the second in world literature. Infestation of human eyes with larvae of flies (myiasis) has been reported. Serious consequences of destructive myiasis are seen in emaciated and diseased patients. Only one report of total destruction of the globe by maggots of Chrysomyia bezziana exists in the literature. As in previous communications, the patient in this report had no predisposing factors both systemic and local. We here in document a case of orbital myiasis leading to rapid destruction of the globe within two days in a healthy and a non-compromised patient. 相似文献
64.
65.
66.
67.
Ramanathan Sundar Varma Shashi Kumar Rao Kolli Madhusudana Muralidharan Srinivasan 《Indian Journal of Thoracic and Cardiovascular Surgery》2004,20(4):164-166
Background Extended trans septal (ETS) approach for mitral valve surgery often divides the artery to the Sino-Atrial node. The clinical
implication of this is contentious. We analyzed our early results with ETS approach.
Methods Between June 1998 and September 2003 eleven patients underwent mitral valve surgery by ETS approach. Six were females. Age
ranged from 19 years to 67 years (median 40 years). Six underwent mitral valve replacement (MVR). Four underwent aortic and
mitral (double) valve replacement (DVR). One had mitral valve repair. Three had additional procedures (tricuspid valve repair=1,
Coronary artery bypass=1, Aorto bifemoral graft=1). Cardiopulmonary bypass ranged from 64 minutes to 77 minutes (median 72
minutes) for MVR and 112 minutes to 178 minutes (median 140 minutes) for DVR. Aortic cross clamp times ranged from 39 minutes
to 52 minutes (median 47 minutes) for MVR and 74 minutes to 120 minutes (median 95 minutes) for DVR.
Results There was no mortality or morbidity attributed to the ETS approach. One early death in emergency DVR was due to heart failure.
Three patients needed seqeuntial pacing in the immediate post-operative period. Nine out of ten survivors were back to their
preoperative rhythms on hospital discharge (6 sinus rhythm; 3 atrial fibrillation). One patient with preoperative trifascicular
block who underwent reoperation to fix a paravalvular mitral leak needed a permanent pacemaker (VVI). The follow-up ranged
from 1 month to 64 months (median 6 months) and is 100% complete. There was no late death or new arrhythmia.
Conclusions Extended trans septal approach is safe. It gives excellent exposure of the mitral valve. division of the sinus node artery
is not deleterious in the short to intermediate term.
Presented at the 50th Annual Meeting of IACTS. New Delhi, Feb. 2004. 相似文献
68.
69.
70.
Joseph G Rajendran Darrell R Fisher Ajay K Gopal Lawrence D Durack Oliver W Press Janet F Eary 《Journal of nuclear medicine》2004,45(6):1059-1064
Radioimmunotherapy (RIT) using (131)I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL). Our approach to treatment planning has been to determine limits on radiation absorbed dose to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific absorbed dose estimates. METHODS: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of (131)I-tositumomab for RIT (January 1990 and April 2003) were reviewed. Serial planar gamma-camera images and whole-body NaI probe counts were obtained to estimate (131)I-antibody source-organ residence times as recommended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. RESULTS: The mean radiation absorbed doses (in mGy/MBq) for our data using the MIRD model were lungs = 1.67; liver = 1.03; kidneys = 1.08; spleen = 2.67; and whole body = 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lungs = 1.30; liver = 0.92; kidneys = 0.76; spleen = 1.40; and whole body = 0.22. We determined the following correlation coefficients between the 2 methods for the various organs: lungs, 0.49 (P = 0.0001); liver, 0.64 (P = 0.004); kidneys, 0.45 (P = 0.0004); spleen, 0.22 (P = 0.0001); and whole body, 0.78 (P = 0.0001), for the residence times. For therapy, patients received mean (131)I administered activities of 19.2 GBq (520 mCi) after adjustment for CT-derived organ mass compared with 16.0 GBq (433 mCi) that would otherwise have been given had therapy been based only using standard MIRD organ volumes-a statistically significant difference (P = 0.0001). CONCLUSION: We observed large variations in organ masses among our patients. Our treatments were planned to deliver the maximally tolerated radiation dose to the dose-limiting normal organ. This work provides a simplified method for calculating patient-specific radiation doses by adjusting for the actual organ mass and shows the value of this approach in treatment planning for RIT. 相似文献