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排序方式: 共有8049条查询结果,搜索用时 15 毫秒
1.
Uwe Schneider PhD Antony Lomax Peter Pemler Jürgen Besserer Dieter Ross Norbert Lombriser Barbara Kaser-Hotz 《Strahlentherapie und Onkologie》2006,182(11):647-652
BACKGROUND AND PURPOSE: There is concern about the increase of radiation-induced malignancies with the application of modern radiation treatment techniques such as intensity-modulated radiotherapy (IMRT) and proton radiotherapy. Therefore, X-ray scatter and neutron radiation as well as the impact of the primary dose distribution on secondary cancer incidence are analyzed. MATERIAL AND METHODS: The organ equivalent dose (OED) concept with a linear-exponential and a plateau dose-response curve was applied to dose distributions of 30 patients who received radiation therapy of prostate cancer. Three-dimensional conformal radiotherapy was used in eleven patients, another eleven patients received IMRT with 6-MV photons, and eight patients were treated with spot-scanned protons. The treatment plans were recalculated with 15-MV and 18-MV photons. Secondary cancer risk was estimated based on the OED for the different treatment techniques. RESULTS: A modest increase of 15% radiation-induced cancer results from IMRT using low energies (6 MV), compared to conventional four-field planning with 15-MV photons (plateau dose-response: 1%). The probability to develop a secondary cancer increases with IMRT of higher energies by 20% and 60% for 15 MV and 18 MV, respectively (plateau dose-response: 2% and 30%). The use of spot-scanned protons can reduce secondary cancer incidence as much as 50% (independent of dose-response). CONCLUSION: By including the primary dose distribution into the analysis of radiation-induced cancer incidence, the resulting increase in risk for secondary cancer using modern treatment techniques such as IMRT is not as dramatic as expected from earlier studies. By using 6-MV photons, only a moderate risk increase is expected. Spot-scanned protons are the treatment of choice in regard to secondary cancer incidence. 相似文献
2.
Sonographic evaluation of gallbladder kinetics: in vitro and in vivo comparison of different methods to assess gallbladder emptying. 总被引:3,自引:0,他引:3
Bernd Wedmann Gabriele Schmidt Martin Wegener Christoph Coenen Dieter Ricken Cornelia Drge 《Journal of clinical ultrasound : JCU》1991,19(6):341-349
In an in vitro study, 10 gallbladders of adult pigs and 6 gallbladders of lambs, all removed immediately after slaughtering, were stimulated in a water bath by electric means to induce active contraction. Gallbladder emptying was followed by ultrasonography employing five measurement procedures: (1) gallbladder width, (2) longitudinal planimetry, (3) transverse planimetry, (4) ellipsoid method, and (5) sum of cylinders method. In an in vivo investigation, gallbladder emptying of 30 volunteers (12 healthy subjects, 18 diabetics) was evaluated in the same way after ingestion of a fatty meal. Gallbladder width was found to be unsuitable to estimate the decrease in gallbladder volume due to a nonlinear relation of the parameters. Longitudinal planimetry tended to be less valid than transverse planimetry in assessing gallbladder volume reduction. The most valid estimation of gallbladder volume decreases was obtained by the two three-dimensional procedures. However, in neither in vitro nor in vivo could a significant difference between the sum of cylinders method and the ellipsoid method in determining relative volume reduction be established. We conclude that a three-dimensional measurement procedure should be used for valid assessments of gallbladder motility. However, according to our data there is no advantage in using the time-consuming sum of cylinders method compared to the simple ellipsoid method. 相似文献
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Uta Lichter-Konecki Christian Benninger Werner E. Brandeis Peter Matthis Dieter Scheffner 《Pediatric hematology and oncology》1987,4(1):77-85
Thirteen children with acute lymphoblastic leukemia (ALL) were investigated before and during cytotoxic therapy. EEG findings were correlated with the clinical course and the therapy protocol and compared with normal data obtained from 295 healthy children. Frequency analysis of the background activity of the EEG revealed an initial slowing of the background activity prior to therapy and further slowing each time a combination of vincristine (VCR), daunorubicine (DAU) or adriblastine (ADR), prednisone (FRED), and L-asparaginase (L-ASP) was administered. The slowing of the background activity correlated only with the administration of these drugs. DAU, ADR, and FRED are not known to influence the EEG; therefore, VCR and L-ASP remain the primary candidates responsible for the central nervous system alteration. 相似文献
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The major limitation in adult-to-adult living donor liver transplantation (LDLT) is an adequate graft size with special regard to the safety of the donor. Only 20% of the evaluated donors are suitable to donate the right liver, depending mainly on the critical remnant liver volume. We report 2 cases of adult-to-adult LDLT using dual grafts. In the first case we implanted a left lateral lobe together with a left lobe; in the second case we used a left lateral and a right lobe. Dual graft LDLT solves the problem of graft-size insufficiency and avoids critical right lobectomy in the donor. This procedure can be safely performed and opens up the possibility of LDLT to even more families in the Western world. 相似文献
9.
James C Halstead David Spielvogel Dieter M Meier Sindy Rinke Carol Bodian Ramin Malekan M Arisan Ergin Randall B Griepp 《European journal of cardio-thoracic surgery》2005,27(4):626-32; discussion 632-3
OBJECTIVE: The indications for aortic root replacement in acute type A dissection are unclear. We reviewed the immediate and long-term outcome of consecutive patients in a series in which a low-threshold policy of composite aortic root replacement had evolved. METHODS: From a prospectively compiled aortic surgery database, we identified 162 patients who had either supracoronary interposition grafting, Group A (n=89), or composite root replacement, Group B (n=73) for acute type A dissection. Patients receiving total arch replacements were excluded. Operative and clinical details were analyzed and patient survival was compared to an age and gender matched census cohort. Need for reoperation on the proximal or distal aorta was also noted. Follow-up totaled 795.5 patient-years. RESULTS: Hospital mortality rates were identical in both groups (12.3%: 11 deaths in group A; 9 in group B). Chronic pulmonary disease, diabetes, malperfusion, hemodynamic compromise and aortic root dilatation were independent risk factors for hospital death. Actuarial survival estimates at 1, 5 and 10 years were 79% (71-88%), 64% (53-75%), and 55% (41-68%) for group A, and 79% (70-86%), 73% (62-83%), and 65% (52-78%) for group B (P=0.48). Age and operative patency of the ascending false lumen were independent risk factors for death after hospital discharge. Proximal aortic reoperation was required for four patients in group A and none in group B (P=0.085). CONCLUSION: A strategy of replacement rather than repair of the dissected aortic root for specific indications in type A dissection yielded high survival and low proximal reoperation rates. These results support an aggressive policy of composite root replacement in acute type A dissection. 相似文献
10.
Gero S M Kinzinger Siegfried J?nicke Dieter Riediger Peter R Diedrich 《American journal of orthodontics and dentofacial orthopedics》2003,124(5):582-590
The outcome of vertical callus distraction of a segment of tooth-supporting alveolar process might be functionally and esthetically unsatisfactory because of the unidirectional impact of intraoral distraction devices. In this case report, we describe how, with a shortened consolidation phase and application of the floating bone effect, the tooth-supporting osteotomy segment can be successfully aligned 3 dimensionally. We applied orthodontic force systems that went beyond the unidirectional vector preset by the mechanical properties of the distraction device. 相似文献